BCH
Maître de Conférences
Scientific activity
Researcher profile
Faculty researcher at the University of Yaoundé I. Grade: Maître de Conférences.
Scientific publications
Arnaud Fondjo Kouam, Eleonore Ngounou, Kerinyuy Juliene Kongnyuy, Mayelle Mepa Mokam, Jordas Casares Tchana Tchamba, Elisabeth Menkem Zeuko’o and 6 more
South African Journal of Botany
Jr Nyambi Nkiackmenyi Ramin, Arnaud Fondjo Kouam, Elisabeth Menkem Zeuko’o, Armel Jackson Seukep, Armelle Gaelle Kwesseu Fepa, Fils Armand Ella and 4 more
PLoS ONE
Cigarette smoke contains numerous toxicants, including cadmium, polycyclic aromatic hydrocarbons (PAHs), tobacco-specific nitrosamines (TSNAs), and volatile organic compounds, all of which may contribute to hepato-renal injury. This study, conducted in Buea (Southwest Region, Cameroon), aimed to assess cadmium inhalation exposure from cigarette smoking as a contributing factor to altered liver and kidney function biomarkers in apparently healthy smokers, while acknowledging that combined exposure to multiple co-toxicants may potentiate organ dysfunction. A survey was used to recruit smokers and collect data on their smoking habits. Cadmium contents in the major cigarette brands selected were used to estimate the cadmium Daily Exposure (DE), Weekly Inhalational Exposure (WIE) and the percentage contribution to the Tolerable Weekly Intake (TWI) of cadmium. Serum alanine aminotransferase (ALT) activity, urea, creatinine contents, and urinary albuminuria and glucosuria were measured in blood and urine samples from smokers and nonsmokers. The 102 smokers enrolled were categorized respectively as light (37.3%; 38/102), moderate (38.2%; 39/102), and heavy (24.5%; 25/102) smokers, smoking an average number of 4.7 ± 0.5, 9.1 ± 1.5, and 19.1 ± 3.0 cigarettes/day, respectively. Cadmium levels in cigarette brands ranged from 0.72-1.08 µg Cd per gram of tobacco removed from the cigarette. Heavy smokers exceeded the permitted cadmium No Significant Risk Level (NSRL) by up to 28-fold, contributing 4-8% to the cadmium TWI. Serum ALT activity and creatinine content were significantly higher (P < 0.05) in smokers groups compared to non-smokers. Also, moderate and heavy smokers were at a significantly higher risk (relative risk 6.90-13.32; P < 0.05) of displaying abnormal elevated serum urea content, positive albuminuria and glucosuria. Our findings demonstrate that healthy active smokers are highly exposed to cadmium (and potentially to other cigarette toxicants) and are at significantly higher risk of displaying abnormally elevated levels of biochemical markers of liver and kidney function, suggesting early signs of organ damage.
Arnaud Fondjo Kouam, Philipe Herman Nfombouot Njitoyap, Brice Fredy Nemg Simo, Cromwel Tepap Zemnou, Kerinyuy Juliene Kongnyuy, Armel Jackson Seukep and 3 more
Microbes & Immunity
Hepatitis E virus (HEV) is a major zoonotic pathogen, and pigs are an important reservoir. Serology for anti-HEV antibodies poorly reflects active infection, while reverse transcription polymerase chain reaction (RT-PCR) is sensitive but not always feasible for large-scale surveillance. This study aimed to develop an immunoglobulin Y (IgY)-based sandwich enzyme-linked immunosorbent assay (ELISA) for direct detection of HEV antigen (HEV-Ag). An antigenic epitope from the HEV open reading frame 2 capsid protein was identified in silico, synthesized, and used to immunize laying hens; IgY was purified from egg yolk and characterized by sodium dodecyl sulfate&ndash;polyacrylamide gel electrophoresis. An in-house sandwich ELISA was subsequently developed using the anti-HEV IgY antibodies. Its diagnostic performance was evaluated against RT-PCR using 350 field-collected pig serum samples and compared with commercial anti-HEV IgG and IgM ELISA kits. Immunization yielded high-purity IgY antibodies, with antigen-specific antibody kinetics showing a significant increase in specific immunoreactivity from week 4 onward and peak sensitivity at weeks 6&ndash;8 post-immunization. The anti-HEV IgY showed high specificity, with no cross-reactivity observed against a heterologous antigen (HBsAg). The optimized sandwich ELISA detected HEV-Ag with a sensitivity of 95.4% and a specificity of 100% relative to RT-PCR. The prevalence of HEV-Ag was 17.7% (62/350), which was not significantly different from RT-PCR (18.6%, 65/350; p=0.250). In contrast, commercial IgG and IgM ELISAs showed high seroprevalence rates (34.9% and 28.3%, respectively) but exhibited significant discrepancies with RT-PCR (p<0.0001), indicating limited utility for identifying active infection. Overall, the developed IgY-based sandwich ELISA demonstrated high diagnostic performance for detecting active HEV infection. This assay represents a viable alternative to RT-PCR for large-scale surveillance, particularly in resource-constrained settings, and may contribute to improved control of zoonotic HEV transmission.
BARTHELEMIE GUEBOTO, Frédéric Nico Njayou, PAUL FEWOU MOUNDIPA
Cameroon Journal of Biological and Biochemical Sciences
Urease is an industrially important enzyme whose production remains limited due to the low availability of the raw material (urease source). Controlling the production of this enzyme can, in view of its many applications, promote the development of importing countries such as Cameroon. This study aimed to extract and characterize urease from Centrosema pubescens for its future valorization. This work is part of the search for local sources of this enzyme through its purification and characterization from Centrosema pubescens. Seeds were germinated at 2, 4, 6, 8, and 10 days, and crude extracts of the enzyme were prepared in an extraction solvent consisting of a mixture of phosphate buffer (pH 7; 0.1 M)/acetone 80/20 v/v to obtain homogenates at 25% w/v, and then centrifuged. Protein content and urease activity were assessed spectrophotometrically. The day of germination on which the germinated seeds showed high enzymatic activity was selected. The crude extract was partially purified using ammonium sulphate precipitation followed by desalting through exclusion chromatography. The presence of urease in the mixture of active fractions was verified by denaturing gel electrophoresis (SDS-PAGE). The kinetic parameters (Vmax and Km) of urease were determined using the kinetic method. The results showed that the 4th day of germination showed the highest specific activity (0.140±0.004 µmol NH4+/min/mg protein) and was chosen as the germination day for the rest of the work. The crude extract from the 4th day was selected for having a purification percentage of 18.78 and a degree of purification of 27.79. The kinetic parameter values for urease under these conditions were: 0.052 ± 0.01 µmol NH4+/min and 0.48 ± 0.153mM for Vmax and Km, respectively, and those for Jack Bean urease were 0.53 ± 0.01 µmol NH4+/min and 0.030 ± 0.01 mM. These observations show that Centrosema pubescens may be a good source of urease. Key words: Urease, Centrosema pubescens, kinetic parameters, plant.
Arnaud Fondjo Kouam, Cromwel Tepap Zemnou, Armel Jackson Seukep, Babayemi Olawale Oladejo, Fredy Brice Nemg Simo, Kerinyuy Juliene Kongnyuy and 4 more
Fitoterapia
Ridel Mbiandou Njami, Ferdinand Kouoh Elombo, Sylvain Nsangou Pechangou, Bradley W. Bolling, Frédéric Nico Njayou, Paul Fewou Moundipa
Journal of Drug Delivery and Therapeutics
Entada africana Polyphenolic Extract (PEE) revealed higher contents of total polyphenols (264.91±1.51mg EAG/g of extract), flavonoids (14.26 ±0.26mg EQ.g of extract) and flavonols (2.1±0.03mg EQ/g of extract). Concentration of Scavenging 50% (CS50) of hydroxyl radical (HOo) radicals with PEE (20.65 ± 0.35 μg/mL) compared to that of vitamin C (7.90 ± 0.00 μg/mL) showed a significant difference at p< 0.05 for HOo scavenging activities. The PEE extract inhibited lipidic peroxidation with IC50 of 9.70 ± 0.21 μg/mL but not significantly different from vitamin C (8.70 ± 0.14 µg/mL). PEE extract have inhibited the production of TNFα with IC50 (71.05 ± 1.20 µg/mL) significantly (p< 0.05) when compared to 25% of methylene chloride fraction of Khaya grandifoliola (32.10 ± 1.13 µg/mL) considered as a standard. For the activation of erythrocytes plasma membrane redox system (PMRS), PEE had an Effective Concentration 50% (EC50) of 8.4 ± 0.00 µg/mL relatively less than that of quercetine 4.6 ± 0.00 µg/mL. Moreover, PEE inhibits proteins oxidation in a dose-concentration manner with an IC50 of 14.60 ± 1.13 µg/mL significantly different (p< 0.05) from that of quercetin (4.60 ± 0.00 µg/mL) considered as a standard. Altogether, PEE could be used as potential antioxidant and anti-Tumor Necrosis Factor alpha (TNFα) ingredient for food and nutrition. Keywords: Entada africana, polyphenols, antioxidant, anti-TNFα, erythrocytes PMRS
Jr Nyambi Nkiackmenyi Ramin, Arnaud Fondjo Kouam, Elisabeth Menkem Zeuko’o, Armel Jackson Seukep, Armelle Gaelle Kwesseu Fepa, Fils Armand Ella and 4 more
Figshare
<div> Cigarette smoke contains numerous toxicants, including cadmium, polycyclic aromatic hydrocarbons (PAHs), tobacco-specific nitrosamines (TSNAs), and volatile organic compounds, all of which may contribute to hepato-renal injury. This study, conducted in Buea (Southwest Region, Cameroon), aimed to assess cadmium inhalation exposure from cigarette smoking as a contributing factor to altered liver and kidney function biomarkers in apparently healthy smokers, while acknowledging that combined exposure to multiple co-toxicants may potentiate organ dysfunction. A survey was used to recruit smokers and collect data on their smoking habits. Cadmium contents in the major cigarette brands selected were used to estimate the cadmium Daily Exposure (DE), Weekly Inhalational Exposure (WIE) and the percentage contribution to the Tolerable Weekly Intake (TWI) of cadmium. Serum alanine aminotransferase (ALT) activity, urea, creatinine contents, and urinary albuminuria and glucosuria were measured in blood and urine samples from smokers and nonsmokers. The 102 smokers enrolled were categorized respectively as light (37.3%; 38/102), moderate (38.2%; 39/102), and heavy (24.5%; 25/102) smokers, smoking an average number of 4.7 ± 0.5, 9.1 ± 1.5, and 19.1 ± 3.0 cigarettes/day, respectively. Cadmium levels in cigarette brands ranged from 0.72–1.08 µg Cd per gram of tobacco removed from the cigarette. Heavy smokers exceeded the permitted cadmium No Significant Risk Level (NSRL) by up to 28-fold, contributing 4–8% to the cadmium TWI. Serum ALT activity and creatinine content were significantly higher (<i>P</i> < 0.05) in smokers groups compared to non-smokers. Also, moderate and heavy smokers were at a significantly higher risk (relative risk 6.90–13.32; <i>P</i> < 0.05) of displaying abnormal elevated serum urea content, positive albuminuria and glucosuria. Our findings demonstrate that healthy active smokers are highly exposed to cadmium (and potentially to other cigarette toxicants) and are at significantly higher risk of displaying abnormally elevated levels of biochemical markers of liver and kidney function, suggesting early signs of organ damage. </div>
Arnaud Fondjo Kouam, Saturine Mengwe Mofor, Madeleine Yvanna Nyangono Essam, Armelle Gaelle Kwesseu Fepa, Elisabeth Menkem Zeuko’o, Armel Jackson Seukep and 4 more
PLoS ONE
The prevalence of type 2 Diabetes Mellitus (T2DM) is increasing globally. Besides the traditional complications associated with T2DM, such as diabetic retinopathy, neuropathy, and kidney diseases, new complications including liver diseases, are increasingly being documented. This study aimed to examine serum biomarkers of liver injury and the related risk factors in T2DM patients at the Buea Regional Hospital, Cameroon. The sociodemographic, clinical, and behavioral characteristics of patients with T2DM were captured using a structured questionnaire. Anthropometric parameters were measured, and the Body Mass Index was calculated. Blood samples were analyzed for biomarkers of liver damage (ALT, AST, GGT, and ALP), considering a liver enzyme profile abnormal if it had more than 2 abnormally elevated values. Bivariate and multivariate logistic regressions analysis were used to identify risk factors, with significance set at P < 0.05. Among the 170 participants recruited, 75.9% were female. The median age was 62 years. Over half (52.9%) were married, 64.7% attended primary school and 55.3% were retired. Also, 59.4% had diabetes for over five years and all reported knowledge of diabetes care. About 73.3% adhered to their medication, 64.7% consumed alcohol, 28.8% smoked tobacco, with 22.4% engaged in physical activity and 77.6% with comorbidities. Blood sugar monitoring was practiced by 80%, with 66.5% having high blood pressure. Healthy weight individuals were 31.2% while 41.2% were obese and 56.5% had abnormal liver enzyme profiles. Five factors: duration of illness, physical inactivity, tobacco smoking, comorbidities and overweight/obesity were significantly (P < 0.05) associated with abnormal liver enzyme profile. Our findings identify risk factors linked to elevated liver enzyme markers indicating liver injury in T2DM patients.
Ridel Mbiandou Njami, Ferdinand Kouoh Elombo, Sylvain Nsangou Pechangou, Bradley W. Bolling, Frédéric Nico Njayou, Paul Fewou Moundipa
Journal of Pharmacognosy and Phytochemistry
A concentrated phenolic compounds extract (KPE) from the plant Khaya grandifoliola was assessed in vitro for antioxidant and anti-inflammatory properties and its effect on erythrocytes Plasma Membrane Redox System (PMRS). Phenolic compounds quantity per g of dry matter (DM) were total phenols (57. 93±0.42mg EGA) and flavonoids (2.84±0.04 mg EQ). Antiradicalar half scavenging concentrations were 6.25±0. 07 μg/mL and 11.65±0.92 μg/mL for DPPH° and HO° tests, respectively. Total Antioxidant Capacity was 76.82±0.35 mgEq AA/g DM and half inhibitory concentrations (IC50) of 8.50±0.14 µg/mL, 8.7±0.14 µg/mL and 71.05±1.20 µg/mL found for inhibition of lipids and proteins oxidation and TNFα production in Jurkat T cells, respectively. KPE activated erythrocytes PMRS with an EC50 of 5.90±0.00 µg/mL. Conclusively, KPE may be suggested as potential ingredient of functional foods against health conditions involving oxidative stress and inflammation.
Jacqueline Manjia Njikam, Emmanuel Mfotie Njoya, Anandaram Harishchander, Aristide Mfifen Munvera, Frank Abimbola Ogundolie, Pierre Mkounga and 3 more
Research Square
Fils Armand Ella, Simon Ngamli Fewou, Mario Robillard Didier Koloko, Pascal Owona, Frédéric Nico Njayou, Paul Fewou Moundipa
American Journal of Biomedical and Life Sciences
Alzheimer’s disease (AD) is a multifactorial, progressive neurodegenerative disorder with dementia and persistent impairment of cognitive functions as the main clinical characteristics. Although signs of progress are being made in developing AD therapy, there is no effective drug capable of stopping and/or slowing down the progression of the disease. We have previously indicated in an in vitro setting of AD that <i>Khaya grandifololia</i> (KG) crude extract possesses antioxidant, anti-inflammatory, and neuroprotective activities. In the current work, we have evaluated the activity of KG hydroethanolic (KG-HE) extract in preventing cognitive impairment and promoting memory improvement in vivo. Results from behavioral tests indicated a significant improvement in memory performance and a delay in depression-like behavior upon treatment of rats with KG-HE extract (5, 25, and 50 mg/kg) or donepezil (1 mg/kg) as standard. Because scopolamine (1 mg/kg) impaired cognitive performance in the tail suspension test, Morris Water Maze test, and Novelty Suppressed Feeding Test, KG-HE extract (5, 25, and 50 mg/kg) or donepezil (1 mg/kg) treatment prevented scopolamine-induced performance impairment. Moreover, both KG-HE extract (5, 25, and 50 mg/kg) and donepezil (1 mg/kg) prevented the scopolamine-induced cognitive impairment by inhibiting the acetylcholinesterase activity. In addition, the brain parameters of stress oxidation (SOD, CAT, and GSH) reduced by scopolamine treatment were regulated by the administration of KG-HE extract or the standard drug donepezil. An increase in the MDA level and the phosphatase activity both in the serum and brain due to scopolamine treatment was restored by the administration of KG-HE extract or donepezil. Taken together, these results suggest that KG-HE extract improves cognition and relieves the scopolamine-induced cognitive impairment via activation of the cholinergic and anti-oxidation systems in rats.
Corinne Raïssa Ngnameko, Jean Jacques Noubiap, Freddy Brice Simo Nemg, Mohamadou Abdou Galdima, Guy Roussel Takuissu-Nguemto, Sophie Ngo-Boumso and 3 more
medRxiv
Abstract Objectives Although global epidemiology of Helicobacter pylori (HP) infection is well characterized, country-specific figure is more accurate for context-specific tailored interventions. The aim was to determine the prevalence, factors associated with infection, antibiotic resistance profile, and genotypes of HP in Cameroon. Design A systematic review with meta-analysis. Participants People living in Cameroon regardless of their clinical profile. Data sources and synthesis Observational studies published in PubMed, EMBASE, African Index Medicus, African Journals Online, and Health Sciences and Diseases up to October 12 th , 2020. Study selection, data extraction, and methodological quality assessment were done by two independent authors. Random-effect meta-analysis served to pool prevalence data. Results Fifteen studies were included. None investigated the genotypes of HP. Among symptomatic patients, the most common used test, urea breath test on gastric biopsy, yielded a prevalence 57.8% (95% confidence interval (CI): 34.3-79.5) of HP infection. This prevalence significantly varied between 47.0% (95%CI: 43.0-51.0) for antigen test in stool samples and 71.2% (95%CI: 59.1-81.9) for Giemsa on gastric biopsy; p = 0.0006. One study in asymptomatic children reported the prevalence of 52.3% (95%CI: 44.9-59.6) using antigen test for stool samples. Among the six studies investigating factors associated with HP infection, one performed a multivariable model and identified being student as protective factor compared to being employed (Odds ratio: 0.09; 95%CI: 0.02–0.49). For antibiotics used for first line treatment, HP was resistant to amoxicillin (85.6-97.1%), metronidazole (93.2-97.9%), and clarithromycin (13.6-44.7%) as reported in two studies. Limitation Data were from six of the ten regions of Cameroon, hindering the generalizability of the findings to the country. Conclusion This study depicted a high prevalence of HP infection and a worrying resistance profile to first-line antibiotics. When waiting for well-conducted studies, updated guidelines are needed for clinical practice for first-line antibiotic treatment. Registration PROSPERO, CRD42020220084. Strengths and limitations of this study Not all the 10 regions of the country were represented in this study, hindering the generalizability of the findings. We were not able to substantially investigate sources of heterogeneity in the prevalence of Helicobacter pylori infection due to scarcity of data. Evidence investigating factors associated with Helicobacter pylori infection are weak and there was scarcity on data exploring antibiotic resistance profile of Helicobacter pylori . This study is the first to provide an estimate of the epidemiology and resistance profile of Helicobacter pylori in Cameroon.
Arnaud Fondjo Kouam, Brice Ayissi Owona, Rodrigue Fifen, Frédéric Nico Njayou, Paul Fewou Moundipa
Heliyon
Entada africana is used in non-conventional medicine for the management of liver ailments. A fraction, designated EaF10 (methylene chloride/methanol 90:10, v/v) with promising hepatoprotective activity has been isolated. Since the mechanisms underlying EaF10 hepatoprotective action remain unknown, this study was undertaken to investigate the anti-hepatotoxic mechanism of the fraction against carbon tetrachloride (CCl 4 )-induced hepatotoxicity and its antioxidant properties. Antioxidant activities of EaF10 were assessed through four chemical antioxidant assays and its anti-hepatotoxic effect evaluated in vivo and in vitro by post-treatment (25 or 100 mg/Kg) or co-treatment (6.25–100 μg/mL) in CCl 4 -intoxicated mice and normal human liver cells line L-02 hepatocytes respectively; and biochemical and molecular parameters assessed respectively by spectrophotometry, and by quantitative real-time polymerase chain reaction and western blot analysis. EaF10 exhibited strong antioxidant activities correlated with its polyphenol content. Serum levels of alanine/aspartate aminotransferase (AST/ALT) and nitrite oxide, liver contents of glutathione (GSH) protein carbonylation and malondialdehyde (MDA), liver activities of catalase (CAT), glutathione-S-transferase (GST) and superoxide dismutase (SOD) and cell viability showed the anti-hepatotoxic effect of EaF10, supported by histopathological observations. The fraction decreased the protein level of Cytochrome P450 2E1 (CYP2E1) and Kelch-like ECH-associated protein-1 (Keap-1), induced nuclear translocation of Nuclear factor-erythroid 2-related factor-2 (Nrf2) coupled to an increase of the mRNA levels of CAT, SOD1 and GST in CCl 4 -intoxicated L-02 hepatocytes. These findings evidenced that the studied plant fraction possesses a strong antioxidant capacity and prevents CCl 4 -induced hepatotoxicity, likely through inhibition of CYP2E1 and activation of the Nrf2 signaling pathway.
Corinne Raïssa Ngnameko, Frédéric Nico Njayou, Muinah Fowora, Frédy Brice Simo Nemg, Paul Fewou Moundipa, Stella Smith
European Journal of Integrative Medicine
Alian Désiré Afagnigni, Maximilienne Ascension Nyegue, Chantal Florentine Ndoye Foe, Youchahou Njankouo Ndam, Frédéric Nico Njayou, Marie Christine Fonkoua and 1 more
Evidence-based Complementary and Alternative Medicine
The present work was undertaken to evaluate antidiarrheal activity of ethanolic leaf extract of Dissotis multiflora (Sm) Triana (D. multiflora) on Shigella flexneri ‐induced diarrhea in Wistar rats and its subacute toxicity. Diarrhea was induced by oral administration of 1.2 × 10 9 cells/mL S. flexneri to rats. Antidiarrheal activity was investigated in rats with the doses of 111.42 mg/kg, 222.84 mg/kg, and 445.68 mg/kg. The level of biochemical parameters was assessed and organs histology examined by 14 days’ subacute toxicity. S. flexneri stool load decreased significantly in dose‐dependent manner. The level of ALT increased ( p < 0.05) in male rats treated with the dose of 445.68 mg/kg while creatinine level increased in rats treated with both doses. In female rats, a significant decrease ( p < 0.05) of the level of AST and creatinine was noted in rats treated with the dose of 222.84 mg/kg of D. multiflora . Histological exams of kidney and liver of treated rats showed architectural modifications at the dose of 445.68 mg/kg. This finding suggests that D. multiflora leaf extract is efficient against diarrhea caused by S. flexneri but the treatment with doses lower than 222.84 mg/kg is recommended while further study is required to define the exact efficient nontoxic dose.
Frédéric Nico Njayou, Arnaud Fondjo Kouam, Brice Fredy Nemg Simo, Angèle N. Tchana, Paul Fewou Moundipa
BMC Complementary and Alternative Medicine
BACKGROUND: Khaya grandifoliola (Meliaceae) and Entada africana (Fabaceae) are traditionally used in Bamun (a western tribe of Cameroon) traditional medicine for the treatment of liver related diseases. In this study, the synergistic hepatoprotective effect of respective active fractions of the plants were investigated against paracetamol-induced toxicity in primary cultures of rat hepatocytes. METHODS: Paracetamol conferred hepatocyte toxicity, as determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay, alanine aminotransferase (ALT), superoxide dismutase (SOD), catalase (CAT) activities, malondialdehyde (MDA) and glutathione (GSH) content assays. The crude extracts were fractionated by flash chromatography and fractions were tested for hepato-(protective and curative) activities. The most active fractions of both plants were tested individually, and in combination based on their respective half effective concentration (EC50). RESULTS: The methylene chloride/methanol fractions of K. grandifoliola (75:25 v/v) (KgF25) and E. africana (90:10 v/v) (EaF10) were found to be the most hepato-protective with EC50 values of 10.30 ± 1.66 μg/ml and 13.47 ± 2.06 μg/ml respectively, comparable with that of silymarin (13.71 ± 3.87 μg/ml). These fractions and their combination significantly (P <0.05) improved cell viability, inhibited ALT leakage and MDA formation, and restored cellular CAT, SOD activities and GSH content. The combination was more effective in restoring biochemical parameters with coefficients of drugs interaction (CDI) less than 1. CONCLUSION: These findings demonstrate that the active fractions have synergistic action in the protection of rat hepatocytes against paracetamol-induced damage and suggest that their hepatoprotective properties may be maximized by using them in combination.
Frédéric Nico Njayou, A. Amougou, Romeo Fouemene Tsayem, Jacqueline Njikam Manjia, Swetha Rudraiah, Bradley W. Bolling and 2 more
Cell Stress and Chaperones
The in vitro antioxidant properties, cytoprotective activity, and ability to induce nuclear translocation of nuclear factor E2-related factor-2 (Nrf-2) of five solvent fractions of the methylene chloride/methanol (1:1 v/v) extract of Khaya grandifoliola (Meliaceae) and Entada africana (Fabaceae) were evaluated. Five antioxidant endpoints were used in the antioxidant activity investigation. The total phenolic content of the fractions was assessed as to the Folin-Ciocalteu method and the profile of interesting fractions analyzed by high-performance liquid chromatography (HPLC). The cytoprotective activity of fractions was determined by H2O2-induced oxidative stress in HC-04 cells by measuring lactate dehydrogenase (LDH) leakage into culture medium. HC-04 cells were used to investigate the ability to induce nuclear translocation of Nrf2. For both plants, the methylene chloride/methanol (90/10; v/v) fraction (F10), methylene chloride/methanol (75/25; v/v) (F25), and the methanolic fraction (F100) were found to have the highest total polyphenol content and exhibited high antioxidant activity strongly correlated with total polyphenol content. The cytoprotective activity of fraction F25 from both plants was comparable to that of quercetin (3.40 ± 0.05 μg/mL), inhibiting LDH leakage with a low half inhibition concentration (IC50) of 4.05 ± 0.03 and 3.8 ± 0.02 μg/mL for K. grandifoliola and E. africana, respectively. Lastly, fraction F25 of K. grandifoliola significantly (P < 0.05) induced nuclear Nrf2 translocation by sixfold, whereas that from E. africana and quercetin was only twofold. The results indicate for the first time that fraction F25 of the studied plants is more antioxidant and cytoprotective and induces nuclear translocation of Nrf2 in a human hepatocyte cell line.
Armelle Tontsa Tsamo, Pierre Mkounga, Frédéric Nico Njayou, José E. Manautou, Kirk Marat, Philip G. Hultin and 1 more
ChemInform
Abstract Title compounds are isolated from the root bark of Trichilia rubescens (Meliaceae) together with 3 known compounds.
Frédéric Nico Njayou, E. C. E. Aboudi, M. K. Tandjang, A. K. Tchana, B.T. Ngadjui, Paul Fewou Moundipa
Khaya grandifoliola (Meliaceae) and Entada africana (Fabaceae ) are traditionally used as source of medicines against liver related d iseases. But the most efficient solvent to extract the plants bioactive compounds h as not yet been found. This work aimed at evaluating and comparing the hepatoprotect ive and antioxidant activities of Hexane (HE), methylenechloride-methanol (MCME) and water (WE) extracts of the plants stem bark. The hepatoprotective activity was evaluated by acetaminopheninduced damage in rat liver slices in measuring lac tate dehydrogenase (LDH) leakage as toxicity marker. The antioxidant activity was as sessed by using 2, 4-diphenyl-1picryl-hydrazil (DPPH), β-carotene-linoleic acid system ( β-CLAMS) and microsomal lipid peroxidation (MLP) assays. The MCME extract of both plants efficiently decreased LDH leakage from liver slices. At the tes ted concentration of 100µg/ml, the hepatoprotective percentage of the extract of K. grandifoliola (87.15%) and that of silymarine (93.73%) were comparable. In the antioxi dant study, the MCME and WE extracts of both plants performed well in inhibitin g MLP assay but, the MCME extracts were the more antioxidant with IC 50 values of 2.7±0.05µg/ml and 0.50±0.07µg/ml comparable with Trolox (2.27±0.52µg/ml) for K. grandifoliola and E. africana , respectively. Phytochemically, many classes of co mpounds including polyphenols were tested positive in the MCME extracts. From the interesting activity of these extracts, it might be concluded that methy lenechloride-methanol (1:1v/v) mixture is the most efficient solvent to extract he patoprotective and antioxidant active principles from K. grandifoliola and E. africana stem bark.
Frédéric Nico Njayou, Paul Fewou Moundipa, Jean Hubert Donfack, Ddp Chuisseu, A. K. Tchana, B.T. Ngadjui and 1 more
International Journal of Biological and Chemical Sciences
This study aimed at evaluating the in vitro antioxidant and hepatoprotective activities of different stem bark extracts of Erythrina senegalensis prepared with ethanol, and the in vivo hepatoprotective activity and acute toxicity of the best extract. The 2, 4-diphenyl-1-picryl-hydrazil (DPPH) and microsomal lipid peroxidation (MLP) models, and the rat liver slices system were respectively used for the in vitro study. The Methylene chloride/methanol (1:1 v/v) (Emc) and 40% ethanolic (E40) extracts were more efficient in inhibiting MLP and in scavenging DPPH radical. However, E40 was most effective with regards to lactate dehydrogenase (LDH) leakage inhibition from rat liver slices intoxicated with carbon tetrachloride (CCl4). The in vivo hepatoprotective activity was evaluated against CCl4-induced hepatotoxicity in rats. The E40 extract (100 mg/Kg) significantly reduced the increase in ALT, AST and lipid peroxidation in liver homogenate, showing that the extract is as protective as silymarin at the same dose. Acute toxicity was evaluated in mice and E40 did not produce any behavioural changes or mortality even at an oral dose of 16 g/kg. The extract was found to contain antioxidant classes of compounds (flavonoids and polyphenols). In conclusion, the E40 extract of E. senegalensis could be an important source of hepatoprotective compounds.Key words: Erythrina senegalensis, stem bark extract, antioxidant, hepatoprotective, carbon tetrachloride.
Frédéric Nico Njayou, Paul Fewou Moundipa, Angèle N. Tchana, Félicité Mbiapo Tchouanguep
Journal of the Cameroon academy of sciences
Arnaud Fondjo Kouam, Saturine Mengwe Mofor, Madeleine Yvanna Nyangono Essam, Armelle Gaelle Kwesseu Fepa, Elisabeth Zeuko’o Menkem, Armel Jackson Seukep and 4 more
Research Square
Fils Armand Ella, Joseph Tchamgoue, Bruno Dupon Akamba Ambamba, Bel Youssouf G. Mountessou, Florine Mbappe Essouman, Nadine Ndoe Essola and 4 more
Fitoterapia
Pascaline M. Deussom, Monique Bassomo Ewonkem, Brice Enang, Michael H. K. Kamdem, Michel Arnaud Mbock, Marthe Carine Djuidje Fotsing and 3 more
Pascaline M. Deussom, Monique Bassomo Ewonkem, Brice Enang, Michael H. K. Kamdem, Michel Arnaud Mbock, Marthe Carine Djuidje Fotsing and 3 more
Pascaline M. Deussom, Monique Bassomo Ewonkem, Brice Enang, Michael H. K. Kamdem, Michel Arnaud Mbock, Marthe Carine Djuidje Fotsing and 3 more
Pascaline M. Deussom, Monique Bassomo Ewonkem, Brice Enang, Michael H. K. Kamdem, Michel Arnaud Mbock, Marthe Carine Djuidje Fotsing and 3 more
Jr Nyambi Nkiackmenyi Ramin, Arnaud Fondjo Kouam, Elisabeth Zeuko’o Menkem, Armel Jackson Seukep, Armelle Gaelle Kwesseu Fepa, Fils Armand Ella and 4 more
medRxiv
Abstract Cigarette smoking in developing countries like Cameroon is increasing with unspecified exposure levels to cadmium, a known toxic chemical. This study conducted in Buea (Southwest Region, Cameroon) aimed to estimate the risk exposure to cadmium inhalation from smoking and its association with the abnormal level of liver and kidney function biomarkers in apparently healthy smokers. A survey recruited smokers to collect data on smoking habits. Cadmium contents in the major cigarette brands selected served to estimate the cadmium Daily Exposure (DE), Weekly Inhalational Exposure (WIE) and the percentage contribution to the Tolerable Weekly Intake (TWI) of cadmium. Serum alanine aminotransferase (ALT) activity, urea, creatinine contents, and urinary albuminuria and glucosuria were measured in blood and urine samples from active and nonsmokers. The 102 smokers enrolled were categorized respectively as light (37.3%; 38/102), moderate (38.2%; 39/102), and heavy (24.5%; 25/102) smokers, smoking an average number of 4.7 ± 0.5, 9.1 ± 1.5, and 19.1 ± 3.0 cigarettes/day, respectively. Cadmium levels in cigarette brands ranged from 0.72-1.08 µg Cd per gram of tobacco removed from the cigarette. Heavy smokers exceeded the permitted cadmium No Significant Risk Level (NSRL) by up to 28-fold, contributing 4-8% to the cadmium TWI. Serum ALT activity and creatinine content were significantly higher ( P <0.05) in smokers groups compared to non-smokers. Also, moderate and heavy smokers were at a significantly higher risk (relative risk 6.90–13.32; P <0.05) of displaying abnormal elevated serum urea content, positive albuminuria and glucosuria. Our findings demonstrated that healthy active smokers are highly exposed to cadmium inhalation and are at higher risk of displaying abnormally increased levels of biochemical markers of liver and kidney functions, indicating risks of organ damage.
Brice Ayissi Owona, Viviane Ndam Ngoungoure, Jordas Tchana Tchamba, Frédéric Nico Njayou, Paul Fewou Moundipa
Metabolic Brain Disease
Arnaud Fondjo Kouam, Philipe Herman Nfombouot Njitoyap, Fredy Brice Nemg Simo, Tepap Cromwell Zemnou, Kerinyuy Juliene Kongnyuy, Elisabeth Menkem Zeuko’o and 2 more
SSRN Electronic Journal
Wilfred A. Abia, Laure Viviane Ndam Ngoungoure, Brice Vincent Ayissi Owona, Yacouba Foupouapouognigni, Ferdinand Kouoh Elombo, Herman Philipe Njitoyap Nfombouot and 3 more
The Neuroscience Chronicles
Introduction: Neurodevelopmental disorders (NDDs) such as autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD) are increasingly prevalent in children globally, including Cameroon. Emerging evidence suggests that early-life exposure to environmental neurotoxins, particularly mycotoxins, may disrupt brain development and contribute to these disorders. Objective: This review aimed to assess the potential impact of dietary exposure to neurotoxic mycotoxins, particularly aflatoxin B1, fumonisin B1, and ochratoxin A, on brain development and the risk of NDDs in children in Cameroon. Methods: A comprehensive review of peer-reviewed studies, national reports, and biomonitoring data from 1993 to 2024 was conducted. Literature on food contamination, mycotoxin toxicology, exposure levels, and neurodevelopmental outcomes in both humans and animal models was synthesized. Results and Discussion: Children in Cameroon are exposed to mycotoxins through contaminated staple foods such as maize and groundnuts, with exposures often exceeding international safety limits. These toxins can cross the blood-brain barrier and placenta, disrupt key neurodevelopmental processes (e.g., neuroplasticity, neurogenesis) through various mechanisms such as oxidative stress, neuroinflammation, mitochondrial dysfunction, and result in behavioral and cognitive impairments. Animal studies show strong links between chronic mycotoxin exposure and NDD-like symptoms. In Cameroon, these risks are intensified by poor food storage, weak regulations, and low dietary diversity. Conclusion: Dietary mycotoxin exposure in children is a serious but underrecognized contributor to adverse neurodevelopmental outcomes in Cameroon. There is an urgent need for national surveillance, child-specific risk assessments, stronger food safety enforcement, and public health education to mitigate exposure and protect vulnerable populations.
Jordas Casares Tchamba Tchana, Brice Ayissi Owona, Nicolas Angélique Messi, Tite Nathan Kouam Kamgue, Abdias Sebdou, Viviane Ngoungoure Ndam and 3 more
International Journal of Biochemistry Research & Review
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive memory loss, cognitive decline, and loss of autonomy. This study aimed to evaluate the therapeutic effects of five biflavonoids extracted from the leaves and stems of Garcinia manni on proteins and events involved in AD development following aluminum chloride (AlCl3) exposure in a drosophila model. Molecular docking studies conducted using Molegro Virtual Docker identified biflavonoids OBIII and DS03 based on their favorable docking scores in regards to molecular targets such as catalase, SOD, nitric oxide synthase, amyloid beta protein, and acetylcholinesterase. Drosophila were exposed to AlCl3 at concentrations of 5, 10, and 20 mM, with 5 mM inducing AD-like symptoms after seven days. Following three days of exposure to this concentration via diet, flies were treated with biflavonoids or baicalin at concentrations of 650 and 6500 µM for four days. Compared to untreated intoxicated flies, experimental groups exhibited significant improvements (p < 0.001) in locomotion and short-term memory. To further investigate the curative effects of the two biflavonoids, seven groups of 50 flies each were established for testing at the aforementioned concentrations. Spectrophotometric assays of oxidative stress and inflammation markers revealed a significant decrease (p < 0.001) in malondialdehyde (MDA) and nitric oxide (NO) production, alongside with increased activity of catalase and superoxide dismutase in biflavonoid-treated groups. All together, these findings position these compounds as promising therapeutic candidates for AD treatment.
Arnaud Fondjo Kouam, Cromwel Tepap Zemnou, Eléonore Ngounou, Felicité Syntia Douanla Somene, Elisabeth Zeuko’o Menkem, Amih Elvis Ofon and 2 more
Journal of Ethnopharmacology
Arnaud Fondjo Kouam, Tepap Cromwell Zemnou, Eléonore Ngounou, Felicité Syntia Douanla Somene, Elisabeth Menkem Zeuko’o, Amih Elvis Ofon and 2 more
SSRN Electronic Journal
Arnaud Fondjo Kouam, Mayelle Mepa Mokam, Eléonore Ngounou, Ferdinand Elombo Kouoh, Rodrigue Fifen, Kerinyuy Juliene Kongnyuy and 6 more
PubMed
Objective: against gentamicin-induced hepato-renal toxicity. Materials and Methods: antioxidant activities. Then, their cytoprotective effects were assessed against gentamicin-induced cytotoxicity in primary mouse hepatocytes. Finally, mice were administered with gentamicin (20 mg/kg) and co-treated with HAG for 14 days, and histopathology, biochemical and molecular parameters related to gentamicin-induced toxicity were evaluated. Results: HAG exhibited outstanding chemical antioxidant activities and preserved hepatocytes from gentamicin-induced cytotoxicity. HAG relieved liver and kidney histopathological and biochemical changes, and enhanced the mRNA level of Nrf2 and its target gene HO-1 in gentamicin-intoxicated mice. Conclusion: HAG attenuates hepato-renal injuries induced by 14-days administration of gentamicin in mice through the activation of Nrf2-antioxidant signaling pathways.
Arnaud Fondjo Kouam, Aristide Mfifen Munvera, Jordas Casares Tchana Tchamba, Elisabeth Menkem Zeuko’o, Armelle Gaelle Kwesseu Fepa, Brice Fredy Nemg Simo and 6 more
Pharmacological Research - Reports
Jeannette Nina Magoudjou Pekam, Noella Molisa Efange, Lakshminarayana Misro, Rodrigue Keumoe, Bruno Lenta Ndjakou, Lawrence Ayong and 3 more
International Journal for Parasitology Drugs and Drug Resistance
Antimalarial resistance is a primary challenge in the treatment of malaria. The ongoing search for novel drug sources remains a critical strategy for addressing this issue. This study evaluated the blood stage antiplasmodial and cytotoxic activities of the crude extract and fractions obtained from Lepidobotrys staudtii . The crude extract and all fractions exhibited promising antiplasmodial activity (IC 50 <10 μg/mL) against all the tested Plasmodium falciparum strains ( Pf 3D7 drug-sensitive and Pf INDO resistant). Notably, the hexane and ethyl acetate fractions exhibited the highest potency, with IC 50 values of 3.73 and 3.4 μg/mL ( Pf 3D7), respectively. No cytotoxic effects were observed at concentrations of up to 500 μg/mL. The ethyl acetate fraction displayed rapid action (12 h of exposure) against the Pf 3D7 and Pf INDO strains. The ring stage parasites were particularly susceptible to the fractions, with IC 50 values ranging from 2.17 to 4.87 μg/mL ( Pf 3D7) and 2.27 to 6.27 μg/mL ( Pf INDO). Additionally, combining the fraction with standard antimalarials at fixed sub-inhibitory concentrations significantly reduced IC 50 values. Only the hexane and crude extracts stimulated reactive oxygen species (ROS) production, whereas the other fractions neutralized the ROS. The most potent ethyl acetate fraction arrested parasite developmental progression and merozoite egress. Phytochemical analyses revealed the presence of phenols, flavonoids, tannins, alkaloids, saponins, carbohydrates, glycosides, and proteins. Reverse Phase High Performance Liquid Chromatography (RP-HPLC) analysis revealed that the fractions comprised a diverse array of compounds, resulting in varying levels of parasite-killing. This study emphasizes the blood-stage antiplasmodial properties of the stem bark extract and fractions of L. staudtii , underscoring their potential as a promising source of antimalarial agents.
Fils Armand Ella, Bruno Dupon Akamba Ambamba, Frédéric Nico Njayou, Paul Fewou Moundipa
IBRO Neuroscience Reports
Background Treatment for complex multifactorial neurological disorders may benefit more from multifunctional chemicals. Dysregulation of monoaminergic pathways and neuroinflammation are typical confluence points in a range of neuropsychiatric and neurodegenerative illnesses. Polypharmacological medications that affect neuroinflammatory and monoaminergic pathways were investigated as potential targets for these diseases. The aim of this study was to investigate the in vitro and in silico multi-target neuroprotective activity of Khaya grandifololia . Methods Decoction and hydro-ethanolic extracts were prepared and screened for their ability to inhibit enzymes related to inflammation (15-lipoxygenase, LOX), neurodegeneration (monoamine oxidase, MAO), and protein glycation and fibrillation using enzymological fluorimetric assays and docking simulations. Results All extracts were able to strongly inhibit the activity of MAO as well as the glycation and fibrillation activities. Also, these extracts moderately inhibited 15-LOX activity. Conclusion These results extend the knowledge on the potential use of Khaya grandifololia to combat multifactorial disorders, giving new approaches into therapeutic avenues for neurodegenerative disease such as Alzheimer's disease.
Laure Viviane Ndam Ngoungoure, Wilfred A. Abia, Brice Vincent Ayissi Owona, Yacouba Foupouapouognigni, Ferdinand Kouoh Elombo, Herman Philipe Njitoyap Nfombouot and 4 more
Developmental Neurobiology
This comprehensive literature review was conducted to identify relevant studies on mycotoxins and brain development in children. Existing studies suggest that mycotoxin exposure during critical periods of brain development may lead to neurocognitive impairments in children. Some studies have reported associations between mycotoxin exposure and reduced cognitive abilities, impaired motor skills, and behavioral problems. Additionally, mycotoxins have been shown to disrupt neural signaling pathways and interfere with neurotransmitter function, potentially contributing to neurodevelopmental disorders. This comprehensive review has provided a comprehensive overview of the possible evidence on the association between mycotoxin exposure and brain development in children and identified areas for future research.
Madeleine Yvanna Nyangono Essam, Arnaud Fondjo Kouam, Armelle Gaelle Kwesseu Fepa, Armel Jackson Seukep, Elisabeth Zeuko’o Menkem, Felicité Syntia Douanla Somene and 3 more
medRxiv
Abstract Malaria and typhoid fever remain major health issues in developing countries like Cameroon, with frequent co-infections. The potential liver damage caused by their respective causative pathogens is overlooked in health management, posing a significant risk of severe liver injury and worsening patient conditions. Accordingly, this study investigated the risk factors associated to liver damage in febrile patients with malaria, typhoid fever, or co-infection at the Obili District Medical Center and Mvog-Betsi Dominican Hospital Center, Yaoundé, Cameroon. During 8 months, 350 febrile patients were evaluated for their adherence to preventive measures concerning malaria and typhoid fever using a structured questionnaire. Blood samples were analyzed for Plasmodium species and Salmonella antibodies and liver enzyme levels were measured. Liver damage was assessed employing the Roussel Uclaf Causality Assessment Method. Risk factors for infections and liver damage were identified using Fisher’s Exact and Chi-Square tests, with significance set at P<0.05. Among participants tested, 129 (36.86%) and 106 (30.29%) were positive for malaria and typhoid, respectively, while 56 (16.00%) were co-infected. Men (58/118 and 44/118) were more affected than women (71/232 and 62/232) for both malaria and typhoid. Participants aged between 20 and 40 years were the most affected by malaria (21.4%) and typhoid fever (17.4%). The non-use of mosquito nets, presence of standing water, bushes, and garbage dumps near residences were significant risk factors (Relative risk: RR>2.1; P<0.0001) for contracting malaria or typhoid fever. The co-infection status (Chi-2 = 18.30; P<0.0001), parasite density (Chi-2 = 9.8; P=0.0074), and delay before consulting (Chi-2 = 13.23; P=0.0013) were significant risk factors for the occurrence of liver injuries. Our findings demonstrated that the alteration of liver enzyme activities, reflecting liver damages among patients with malaria, typhoid, or malaria-typhoid co-infection, is a reality and should be considered during the patient’s treatment.
Madeleine Yvanna Nyangono Essam, Arnaud Fondjo Kouam, Armelle Gaelle Kwesseu Fepa, Armel Jackson Seukep, Elisabeth Menkem Zeuko’o, Felicité Syntia Douanla Somene and 3 more
PLoS ONE
Malaria and typhoid fever remain major health issues in developing countries like Cameroon, with frequent co-infections. The potential liver damage caused by their respective causative pathogens is overlooked in health management, posing a significant risk of severe liver injury and worsening patient conditions. Accordingly, this study investigated the risk factors associated with liver damage in febrile patients with malaria, typhoid fever, or co-infection at the Obili District Medical Center and Mvog-Betsi Dominican Hospital Center, Yaoundé, Cameroon. Over 8 months, 350 febrile patients were evaluated for their adherence to preventive measures concerning malaria and typhoid fever using a structured questionnaire. Blood samples were analyzed for Plasmodium species and Salmonella antibodies and liver enzyme levels were measured. Liver damage was assessed using the Roussel Uclaf Causality Assessment Method. Risk factors for infections and liver damage were identified using Fisher's Exact and Chi-Square tests, with significance set at P < 0.05. Among participants tested, 129 (36.86%) and 106 (30.29%) were positive for malaria and typhoid, respectively, while 56 (16.00%) were co-infected. Men (49.2% and 37.3%) were more affected than women (30.6% and 26.7%) for both malaria and typhoid, respectively. Participants aged between 20 and 40 years were the most affected by malaria (21.4%) and typhoid fever (17.4%). The non-use of mosquito nets, presence of standing water, bushes, and garbage dumps near residences were significant risk factors (Relative risk: RR > 2.1; P < 0.0001) for contracting malaria or typhoid fever. The co-infection status (Chi-2 = 18.30; P < 0.0001), parasite density (Chi-2 = 9.8; P = 0.0074), and delay before consulting (Chi-2 = 13.23; P = 0.0013) were significant risk factors for the occurrence of liver injuries. Our findings demonstrated that the alteration of liver enzyme activity, reflecting liver damage among patients with malaria, typhoid, or malaria-typhoid co-infection, is a reality and should be considered during the patient treatment.
Pascaline M. Deussom, Monique Bassomo Ewonkem, Brice Enang, Michael H. K. Kamdem, Michel Arnaud Mbock, Marthe Carine Djuidje Fotsing and 3 more
Royal Society Open Science
The development of multifunctional drugs from anti-inflammatory agents is a promising strategy for people with several inflammation-related comorbidities since such medicines could reduce complications, improve health outcomes and lower healthcare costs. In this study, esters of ibuprofen, cinnamic and salicylic acids were synthesized and characterized by spectroscopic methods, with six new compounds identified. Cytotoxicity and anti-inflammatory properties were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium assay in mouse-derived peritoneal macrophages, which were obtained following an intraperitoneal injection of 0.5 ml of a 2% starch solution. All the tested compounds were safe up to 50% concentrations (2.41 × 10⁻⁴ to 2.41 mM), and monoethylene glycol di-ibuprofen ( 2 ) displayed the highest toxicity (IC 50 = 4.90 mM). Most compounds were non-toxic below 2.41 mM, and all inhibited nitric oxide (NO) production in a concentration-dependent manner at 0.24 mM. Ibuprofen and cinnamic acid derivatives ( 2 , 3 , 5a and 14 ) exhibited enhanced anti-inflammatory effects, with IC 50 = 0.002 mM for monoethylene glycol mono-ibuprofen ( 3 ), while fatty-acid ester salicylates ( DEW4 ) demonstrated weaker NO inhibition. Antioxidant tests (2,2-diphenyl-1-picrylhydrazyl, ferric reducing ability of plasma and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS)) showed limited activities, with few compounds reducing the ABTS+ radical (0.1 ˂ SC 50 ˂ 0.2 mM). Compounds 3 , 5a , 7 , 12 and 14 are potential new anti-inflammatory drugs, while 2 may have anti-cancer properties.
Doriane Perlise Lienou, Corinne Raïssa Ngnameko, Fils Armand Ella, Marie Atsama Amougou, Arnaud Fondjo Kouam, Jacqueline Njikam Manjia and 3 more
Exon.
Urease is an enzyme that plays a significant role in the pathogenesis of Helicobacter pylori responsible for numerous health issues, among which chronic gastritis, peptic ulcer disease, gastric neoplasia and even stomach cancer. Therefore, targeting urease represents a key strategy to attenuate gastritis induced by H. pylori. Khaya grandifoliola (KG) and Entada africana (EA) were prepared using methylene chloride/methanol (1:1, v/v). After that, the extracts were fractionated using a gradient of solvent and the anti-urease activities of crude extracts and fractions was evaluated. Mechanism of inhibition of urease by the most active fractions was determined using kinetic method. Polyphenols and flavonoids contents were determined. Extracts and fractions of KG and EA exhibited a significant inhibition of urease activity. The half inhibitory concentration (IC50) of KG (31.61 ± 0.23 µg/mL) and EA (35.70 ± 0.14 µg/mL) showed no significantly difference (P > 0.05) to the reference Thiourea (30.37 ± 0.30 µg/mL). In addition, the kinetic study revealed that the methanolic fraction (FMeOH) of KG and EA strongly inhibited the activity of urease with IC50 values of 31.60 ± 1.25 and 29.00 ± 1.05 µg/mL respectively. These fractions exhibited mixed-type inhibition with Kic and Kia values of 9.96 and 91.15 µg/mL for KG and 13.24 and 226.59 µg/mL for EA respectively. Both extracts contain phenolic compounds. Overall, this study indicated a high anti-urease activity of the methanolic fraction of KG and EA. Each fraction exerts a mixed inhibition on urease activity.
Jacqueline N. Manjia, Emmanuel Mfotie Njoya, Harishchander Anandaram, Aristide Mfifen Munvera, Frank Abimbola Ogundolie, Pierre Mkounga and 3 more
Revista Brasileira de Farmacognosia
Fils Armand Ella, Thaddée Boudjeko, Frédéric Nico Njayou
International Journal of Science and Research Archive
Numerous plant polysaccharides have demonstrated immunomodulatory and antioxidant potentials, and can be investigated as novel molecules with biological properties that may enhance immune function. The aim of this study was to assess the antioxidant and immunomodulatory properties of cell wall polysaccharides fractions isolated from Harungana madagascariensis (HM). Pectin fraction (PF) and hemicellulose fraction (HCF) were extracted and tested for their antioxidant properties using reducing power, 1,1-diphenyl-2-picryl hydrazyl (DPPH) and 2,2′-azino-bis-3-éthylbenzylthiazoline6-sulphonic acid (ABTS) radical scavenging assays, chelating activity and inhibition of lipid peroxidation. Their immunomodulatory activities were carried out on peritoneal macrophages targeting NADH oxidase and lysosomal enzyme activities as well as the production of nitric oxide (NO) and hydroperoxides (H2O2) during phagocytosis of Saccharomyces cereviceae. The polysaccharides fractions showed significant antioxidant and immunostimulatory activities via stimulation of NADH oxidase and lysosomal enzyme of peritoneal macrophages and production of NO and H2O2. Taken together, the results of this study indicate the potential of polysaccharides from H. madagascariensis as antioxidant and immunomodulator agents.
Pascaline M. Deussom, Monique Bassomo Ewonkem, Brice Enang, Michael H. K. Kamdem, Michel Arnaud Mbock, Marthe Carine Djuidje Fotsing and 3 more
Pascaline M. Deussom, Monique Bassomo Ewonkem, Brice Enang, Michael H. K. Kamdem, Michel Arnaud Mbock, Marthe Carine Djuidje Fotsing and 3 more
Jacqueline Njikam Manjia, Apeksha Joshi, Emmanuel Mfotie Njoya, Kapil K. Upadhyay, Corinne Raïssa Ngnameko, Lyndy J. McGaw and 3 more
Current Drug Research Reviews
`Background: Harungana madagascariensis (HM) and Psorospermum aurantiacum (PA), used traditionally for skin care, have been reported to upregulate the expression of intracellular antioxidant genes, thereby preventing melanoma and protecting fibroblast cell lines from Ultraviolet B (UVB)-induced intracellular oxidative stress. Aims: This investigation aimed to identify major compounds in bioactive fractions using bioassay- guided fractionation. Methods: The anti-inflammatory effect of fractions was determined by measuring their inhibitory activity on 15-lipoxygenase and nitric oxide (NO) in lipopolysaccharide-stimulated RAW 264.7 macrophage cells. Additionally, the anti-aging efficacy of the fractions was determined by assessing the expression of markers for the aging process, i.e., expression of tyrosinase (TYR), tyrosinase-related protein-1 (TRP-1), procollagen type-1 (COL1A1), and matrix metalloproteinase- 1 (MMP-1) in UVB-induced photoaging in skin cell-lines. Furthermore, UHPLCMS- based identification of the bioactive compounds from the most prominent fraction was also carried out. Results: Hexane fraction of HM significantly inhibited (p < 0.05) the 15-lipoxygenase (IC50 = 46.80 μg/mL) and NO production (IC50 = 66.55 μg/mL), whereas hexane fraction of PA was effective (p < 0.05) in inhibiting 15-lipoxygenase activity (IC50 = 27.55 μg/mL). Furthermore, the hexane fraction of HM and methanol fraction of PA were significantly effective (p < 0.05) in reverting the UVB-mediated altered expressions of MMP-1, TYR, TRP-1, and COL1A1. Furthermore, hexane fraction of HM revealed the presence of harunganin and betulinic acid, whereas vismion D, vismin, kenganthranol B, and bianthrone 1a were identified from the methanol fraction of PA. Conclusion: Overall, the hexane fraction of HM and methanol fraction of PA displayed effective anti-aging activities, with additional anti-inflammatory effects.
Arnaud Fondjo Kouam, Ibrahim Njingou, Nina Jeannette Pekam Magoudjou, Hamed Bechir Ngoumbe, Philipe Herman Nfombouot Njitoyap, Elisabeth Menkem Zeuko'o and 2 more
Pharmaceutical Science Advances
The use of N-acetylcysteine against acetaminophen(APAP)-induced hepatotoxicity, a leading cause of liver injury, has several drawbacks, including short therapeutic windows. Khaya grandifoliola (Meliaceae) has been traditionally used to manage liver-related diseases, and many reports have confirmed its hepatoprotective properties. However, its therapeutic potential as an antidote against APAP-induced hepatotoxicity has yet to be proven in a clinically relevant model. This study aimed to verify the efficacy of delayed treatment with the hydroethanolic extract of K. grandifoliola (KgE) in suppressing the early injury phase of APAP pathophysiology. KgE was analyzed using HPLC/UV. Acute oral toxicity tests were conducted in mice to determine the therapeutic dose of KgE. Mice were treated with 300 mg/kg APAP; 1h and 12h later, they were treated with either predetermined doses of KgE or 20 mg/kg c-Jun N-Terminal Kinase (JNK) inhibitor SP600125, which served as a reference antidote. At 6h and 24h after APAP treatment, the parameters of liver damage and mitochondrial dysfunction, phosphorylation of JNK, and mitochondrial translocation were assessed. KgE at a dose of 5000 mg/kg was safe for mice. Accordingly, 100, 200, and 400 mg/kg were selected as curative treatments. Delayed administration of KgE reversed the histopathological changes in the liver, inhibited serum levels of alanine aminotransferase, reduced the liver content of nitric oxide and malondialdehyde, and restored hepatic glutathione pools and superoxide dismutase and catalase activities in APAP-intoxicated mice. Moreover, KgE prevented APAP-induced JNK phosphorylation and p-JNK mitochondrial translocation and rescued the activities of mitochondrial enzyme complexes II and V. HPLC/UV analysis revealed the presence of gallic acid, Quercetin and Silibinin, with retention times of 3.77, 11.63 and 11.95 min as the major active ingredients present in KgE. Our findings demonstrate that post-treatment with KgE protects the mouse liver from APAP-hepatotoxicity through the inhibition of JNK activation and mitochondrial dysfunction.
Arnaud Fondjo Kouam, Florence Déclaire Mabou, Lifeng Fu, Roméol Romain Koagne, Yan Li, Brice Ayissi Owona and 7 more
South African Journal of Botany
Highly pathogenic coronaviruses, including the Middle East Respiratory Syndrome Coronavirus (Mers-CoV) and Severe Acute Respiratory Syndrome Coronavirus-2 (Sars-CoV2), have recently emerged and represent a serious threat to global health. Accordingly, a search for potent inhibitors against coronavirus diseases is warranted. Therefore, this study aimed at identifying potential inhibitors from Crinum distichum against the papain-like protease (PLpro), an important antiviral target due to its essential role in viral replication. A bacterial expression system was used for the recombinant expression of Mers-CoV-PLpro and Sars-CoV2-PLpro which was used to assess the inhibitory effect of compounds isolated from C. distichum against their proteolytic and deubiquitinating (DUB) activities. Then, the inhibition mechanism of hit compounds was determined through enzyme kinetic studies. Protein-ligand stability was assessed by Differential Scanning Fluorometry and Molecular docking was used to predict the possible molecular interactions. Five compounds, namely (2 S )-4´,7-dimethoxyflavan (CDS1), (2 S )-4´‑hydroxy-7-methoxyflavan (CDS2), Hippadine (CDS3), (2 R )-4´‑hydroxy-5,7-dimethoxyflavan (CDS4) and Hippacine (CDS5) were tested in this study. They markedly inhibited both the proteolytic and deubiquitinating activities of CoV-PLpro. Their IC 50 values were in the low micromolar range. The most potent inhibitors were CDS3 and CDS4, with IC 50 values of 9.28 and 6.45 µM, and 11.63 and 6.10 µM against the proteolytic and DUB activities of Mers-CoV-PLpro and Sars-CoV2-PLpro, respectively. They exert their inhibitory effect through competitive and non-competitive inhibition mechanisms. These compounds induced the instability of the enzymes by reducing their melting temperature and molecular docking analysis revealed several molecular interactions between the compounds and various amino acids of the enzymes. Overall, our findings suggest C. distichum active constituents to be promising candidates for development into potential inhibitors against coronavirus .
Marie Louise Medoua, Sylvain Nsangou Pechangou, Brice Enang, Assam Assam Jean Paul, Emmanuel Mfotie Njoya, Frédéric Nico Njayou and 1 more
Asian Journal of Research in Medical and Pharmaceutical Sciences
Aims: The present work aimed to evaluate the anti-amoebic, antibacterial, and anti-inflammatory potential of three natural polyketides from Phomopsis sp. CAM212.
 Study Design: Clinical isolates of E.histolytica, E.coli ATCC25922 strain, primary peritoneal mouse macrophages and three polyketides were used.
 Places and Duration of Study: Laboratory of Pharmacology and Toxicology, Laboratory of Medical Microbiology, Faculty of Science, University of Yaounde 1 between May and December 2022.
 Methodology: During this work, we evaluated the ability of three natural polyketides from Phomopsis sp to inhibit the growth of germs responsible for amoebic and bacillary dysentery. First, the anti-amoebic activity was carried out on clinical isolates of E. histolytica in polyxenic culture. Subsequently, we evaluated the antibacterial potential on a strain of E. coli ATCC25922. Finally, the anti-inflammatory potentials were evaluated on a primary culture of SC activated macrophages through inhibition of nitric oxide (NO) production, activation of phosphatase alcaline (ALP) and inhibition of 5-lipoxygenase (5-LOX).
 Results: It emerges from this work that among compounds, phomopsinin B, presented the highest anti-amoebic potential (84.4 % inhibition after 72h) and the highest antibacterial potential (MIC=12.5µg/mL and MBC/MIC=2). Phomopsini A and phomopsini A acetate showed moderate anti amoebic and antibacterial potentials. However, all these activities remain lower than that of metronidazole and ciprofloxacin (90% of amoebic inhibition after 72h; MIC=0.72µg/mL and MBC/MIC=4). Subsequently, all tested compounds were nontoxic on primary macrophages. Phomopsinin B exhibited a great anti-inflammatory potential through the inhibition of NO production (IC50=1.72±0.91µg/mL); inihibition of 5-LOX activity (IC50=36.97±7.12µg/mL) and activation of ALP activity (IC50=0.13±0.01µg/mL) as compared to Baicalin the standard. The anti-inflammatory potential of phomopsinin A and phomopsinin A acetate were lower compared to baicalin.
 Conclusion: Ultimately, among compounds tested, phomopsinin B exhibited the best anti-amoebic, antibacterial and ant-inflammatory potential similar to the respective standards within the limits of the tests carried out.
Sylvain Nsangou Pechangou, Charifa Ngbetkom Mandou, Carine Matsigang Fondjou, Vigny Sayal Ngohoba, Edie Brice Enang, Ibrahim Njingou and 3 more
Journal of Biosciences and Medicines
Codiaeum variegatum has been widely investigated for its biological proprieties ranging from the antiamoebic potential to the phytochemical analysis. The aim of the present study was to evaluate the anti-inflammatory potential of C. variegatum leaf extracts and fractions. A primary macrophage culture activated by Saccharomyces cereviseae (SC) was used to evaluate cell cytotoxicity and anti-inflammatory potential of the plant extracts and fractions. Macrophages were treated with different concentrations (0.1; 1; 10 and 100 μg/mL) of the extracts/fractions for the inhibition of 5-lipoxygenase activity, nitric oxide (NO) and Tumor Necrosis Factor Alpha (TNF-α) production. No significant difference was observed on cell viability in the presence of extracts and fractions at tested concentration during the incubation period. Extracts and fractions of C. variegatum inhibited the 5-lipoxygenase activity, NO and TNF-α production by viable primary mouse macrophages in a concentration-dependent manner. The fractionation process increased anti-inflammatory activity. Among fractions, HEF2, HEF3, HEF5, EEF1, EEF3 and EEF5 exhibited the best anti-inflammatory potential. C. variegatum extracts and fractions exhibited a greater anti-inflammatory potential throughout the inhibition of pro-inflammatory mediators such as NO, 5-Lox and TNF-α.
Sylvain Pechangou Nsangou, Roukayatou Ndiandoukoue Ndam, Emmanuel Mfotie Njoya, Brice Enang, Frédéric Nico Njayou, Paul Fewou Moundipa
Investigational Medicinal Chemistry and Pharmacology
Background: Sida rhombifolia (L) is a medicinal plant from tropical regions belonging to the Malvaceae family and the plantea kingdom. It is known for its multiple pharmacological properties. The aim of this work was to evaluate the anti-amoebic, and anti-inflammatory potential of Sida rhombifolia aqueous and ethanolic leaf and stem extracts harvested in two localities of Cameroon (Yaoundé and Massangam in the Centre and West regions, respectively). Methods: The anti-amoebic activity was evaluated on a polyxenic culture of Entamoeba histolytica. A primary macrophage culture activated by Saccharomyces cereviseae (SC) was used to evaluate anti-inflammatory potential of the plant extracts. Macrophages were treated with different concentrations (1; 10; 100 and 500 μg/mL) of the extracts for the inhibition of nitric oxide (NO) production and 5-lipoxygenase activity. Methods: The anti-amoebic activity was evaluated on a polyxenic culture of Entamoeba histolytica. A primary macrophage culture activated by Saccharomyces cereviseae (SC) was used to evaluate the anti-inflammatory potential of the plant extracts. Macrophages were treated with different concentrations (1; 10; 100 and 500 μg/mL) of the extracts for the inhibition of nitric oxide (NO) production and 5-lipoxygenase activity. Results: No significant difference was found between the anti-amoebic activity of the ethanolic extract of Yaoundé (Centre region, IC50 = 7.71 μg/mL) and that of ethanolic leaf extract from Massagam (West region IC50 = 7.77 μg/mL) after 72 hours. Among the extracts, ethanolic leaf extracts exhibited the highest anti-amoebic activity after 72 hours of treatment. Metronidazole showed better activity (IC50 = 5.96 µg/mL) in the same periods of time. Phenolic compounds and flavonoid contents were higher in Yaoundé (Centre region) ethanolic leaf extract, proving that these extracts can prevent certain damages linked to a state of oxidative stress. The ethanolic extracts of the leaves significantly inhibited NO production and 5-lipoxygenase activity in macrophages (IC50 of 3.85 µg/mL; 3.99 µg/mL and 36.64 µg/mL; 73.22 µg/mL respectively). Conclusion: This preliminary study shows that the ethanolic extract of S. rhombifolia possesses better anti-amoebic properties and can act at the level of the intestinal mucosa in order to fight against the damage linked to the dysfunction of the inflammatory cells.
Sylvain Nsangou Pechangou, Carine Matsingang Fondjou, Charifa Ngbetnkom Mandou, Sunil Kumar, Mfotie Njoya Emmanuel, Frédéric Nico Njayou and 2 more
American Journal of Plant Sciences
Amoebiasis, classified as the third intestinal parasitic infection, represents a public health problem in low-income countries where hygiene and sanitation conditions are poor. With the resurgence of resistant pathogenic strains as well as ancestral considerations in developing countries such as Cameroon, many people rely on medicinal plants to treat a plethora of diseases. This work aimed to highlight the anti-amoebic and anti-oxidant potential of Codiaeum variegatum extracts and fractions. The anti-amoebic potential of C. variegatum was assayed on the polyxenic culture of the clinical isolates of E. histolytica. Then, the anti-oxidant potential of the ethanolic/hydroethanolic extracts and fractions was evaluated through DPPH radical scavenging, iron reduction (FRAP), lipid peroxidation inhibitory potential and total antioxidant capacity tests followed by the determination of phenolic compound and flavonoid content. It was found that the fractionation process decreased the amoebicidal activities of C. variegatum leaf extracts. However hydroethanolic extract (CI50: 10.08 ± 0.42, 5.18 ± 0.09, 5.18 ± 0.09 μg/mL respectively after 24, 48 and 72 hours) was more active than ethanolic extract (CI50: 15.59 ± 6.17; 9.61 ± 2.37; 6.26 ± 3.22 μg/mL respectively after 24, 48 and 72 hours). Interestingly, the activities of hydroethanolic extract were significantly non-different compared to metronidazole CI50: 8.42 ± 0.44, 6.45 ± 0.22 and 3.42 ± 0.33 μg/mL, respectively after 24, 48 and 72 hours). Ethanolic extract and EF5 showed higher Phenolic compound contents and higher antioxidant activity than hydroethanolic extract and other fractions through DPPH radical scavenging power (EC50 = 311.50 ± 4.12 μg/mL) and total antioxidant capacity (44 ± 0.07 mgEAA/gF). However, these activities are significantly lower than those of ascorbic acid (EC50 = 31.20 ± 4.39 μg/mL, and 61.34 ± 4.42 μg/mL respectively). This low antioxidant activity was confirmed by poor phenolic and flavonoid compounds contents found in the extracts and fractions. The present result brings a new approach to the ethnopharmacological uses of C. variegatum against dysentery in cases associated with Amoebiasis in Cameroun.
Arnaud Fondjo Kouam, Noé Auguste Nseké Ngoumé, Armelle Gaelle Kwesseu Fepa, Zerubabel Wainfen, Eléonore Ngounou, Borris Rosnay Galani Tietcheu and 4 more
Egyptian Liver Journal
Abstract Background Malaria is an endemic mosquito-borne disease in sub-Saharan regions, including Cameroon. Due to the obligatory hepatic stage of its pathogenic agents, malaria can induce liver damage if not properly treated. Hence, we assessed the impact of malaria infection on liver transaminases among febrile patients consulting at the Deido District Hospital, Douala-Cameroon, in regard to their attitude towards the practice of preventive measures, treatment, and management of malaria. Methods Over 10 weeks, 150 febrile patients and 28 healthy individuals serving as the control group were enrolled and their blood samples screened for Plasmodium species by Giemsa Staining and liver injury evaluated by measuring the serum level of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. The socio-demographic characteristics of participants and their attitude towards the practice of preventive measures, treatment, and management of malaria were collected using a structured- questionnaire. Results Among tested febrile patients, 113 (75%) were malaria-positive. Females were more affected (65.5%) than males; the most affected age group were adults between 30-60 years (55.8%). A significant association (p˂0.05; relative risk [RR] = 1.424 or p˂0.05; RR = 1.947) was found between malaria infection and non-use of mosquito nets or insecticides, respectively. The serum level of ALT and AST activities in malaria-positive were significantly ( p <0.05) increased, compared to healthy or malaria-negative individuals. Furthermore, transaminase activity was significantly ( p <0.05) elevated in non-practitioners of preventive measures; and in patients who engaged in auto-medication or traditional medication, compared to those who sought treatment from health centers. Conclusion Our findings demonstrated that non-practice of preventive measures, improper treatment and management of malaria infection can lead to an abnormal increase in serum level of transaminases which may reflect liver injury.
Brice Enang, Sylvain Nsangou Pechangou, Frédéric Nico Njayou, Marie Louise Medoua, Paul Fewou Moundipa
Zenodo (CERN European Organization for Nuclear Research)
<strong>Background</strong>: Wild edible fruits are good source of phenolic compounds such as anthocyanins. Those compounds are known for their anti-inflammatory potential. They interact with many mediators of the physiopathological pathway such as NF-kB which is at a central position in the inflammatory response in macrophages. This study aimed to determine the anti-inflammatory and antioxidant potential of ten wild edible fruits aqueous extracts. <strong>Methods: </strong>The antioxidant potential was evaluate through the DPPH, ABTS and OH radical scavenging activity; the ferric reducing agent power and the total antioxidant capacity assessment. Also, the total phenolic and flavonoids, anthocyanins compounds and vitamin C content were assayed. For the anti-inflammatory activity, a primary macrophage culture was used. Inflammatory mediators such as nitric oxide (NO), alkaline phosphatase, NADPH oxidase and 5-lipoxigenase activity was assayed. <strong>Results: </strong><em>Alchornea cordifolia</em> and <em>Pentaclethra macrophylla </em>extracts showed the greatest antioxidant activity respectively (Antiradical power (AP)=5.82 mol of DPPH/mg of extract and AP=5.05 mol of DPPH/mg of extract for DPPH scavenging assay); (IC<sub>50</sub>=1.62µg/ml and IC<sub>50</sub>=1.60µg/ml for ABTS radical scavenging assay); (IC<sub>50</sub>=32.67µg/ml and IC<sub>50</sub>=70.01µg/ml for OH radical scavenging assay) and (EC<sub>50</sub>=54.06µg/ml and EC<sub>50</sub>=17.46µg/ml for ferric reducing antioxidant power) with a non-significant difference with the reference compound. For the anti-inflammatory activity, firstly it has been observed that <em>Alchornea cordifolia’s </em>extract exhibits the greatest potential against NADPH oxidase activity inhibition (IC<sub>50</sub>=36.20µg/ml); alkaline phosphatase activation (EC<sub>50</sub>=0.27µg/ml) with non-significant difference with the reference compound. Secondly, <em>Pentaclethra macrophylla’s</em> extract demonstrated a high ability to inhibit NO production (IC<sub>50</sub>=5.79µg/ml) and 5-lipoxigenase (IC<sub>50</sub>=1.41µg/ml). <strong>Conclusion: </strong>From the results obtained the assessed wild fruit extracts appears to be good sources for anti-inflammatory and antioxidant bioactive molecules. They could be beneficial for the research of new modulators for the management of inflammatory disorders.
Brice Enang, Sylvain Nsangou Pechangou, Frédéric Nico Njayou, Marie Louise Medoua, Paul Fewou Moundipa
World Journal of Advanced Research and Reviews
Background: Wild edible fruits are good source of phenolic compounds such as anthocyanins. Those compounds are known for their anti-inflammatory potential. They interact with many mediators of the physiopathological pathway such as NF-kB which is at a central position in the inflammatory response in macrophages. This study aimed to determine the anti-inflammatory and antioxidant potential of ten wild edible fruits aqueous extracts. Methods: The antioxidant potential was evaluate through the DPPH, ABTS and OH radical scavenging activity; the ferric reducing agent power and the total antioxidant capacity assessment. Also, the total phenolic and flavonoids, anthocyanins compounds and vitamin C content were assayed. For the anti-inflammatory activity, a primary macrophage culture was used. Inflammatory mediators such as nitric oxide (NO), alkaline phosphatase, NADPH oxidase and 5-lipoxigenase activity was assayed. Results: Alchornea cordifolia and Pentaclethra macrophylla extracts showed the greatest antioxidant activity respectively (Antiradical power (AP)=5.82 mol of DPPH/mg of extract and AP=5.05 mol of DPPH/mg of extract for DPPH scavenging assay); (IC50=1.62µg/ml and IC50=1.60µg/ml for ABTS radical scavenging assay); (IC50=32.67µg/ml and IC50=70.01µg/ml for OH radical scavenging assay) and (EC50=54.06µg/ml and EC50=17.46µg/ml for ferric reducing antioxidant power) with a non-significant difference with the reference compound. For the anti-inflammatory activity, firstly it has been observed that Alchornea cordifolia’s extract exhibits the greatest potential against NADPH oxidase activity inhibition (IC50=36.20µg/ml); alkaline phosphatase activation (EC50=0.27µg/ml) with non-significant difference with the reference compound. Secondly, Pentaclethra macrophylla’s extract demonstrated a high ability to inhibit NO production (IC50=5.79µg/ml) and 5-lipoxigenase (IC50=1.41µg/ml). Conclusion: From the results obtained the assessed wild fruit extracts appears to be good sources for anti-inflammatory and antioxidant bioactive molecules. They could be beneficial for the research of new modulators for the management of inflammatory disorders.
Sylvain Nsangou Pechangou, Brice Enang, Vigny Sayal Ngohoba, Emmanuel Mfotie Njoya, Frédéric Nico Njayou, Paul Fewou Moundipa
Journal of Exploratory Research in Pharmacology
Codiaeum variegatum (C. variegatum), which is commonly known as garden croton, is a medicinal plant used for the treatment of amoebiasis in Cameroon and some Asian countries. The present study aims to evaluate the antioxidant and anti-inflammatory activities of the stem crude extracts of C. variegatum.
Arnaud Fondjo Kouam, Micheline Masso, Ferdinand Elombo Kouoh, Rodrigue Fifen, Ibrahim Njingou, Angèle N. Tchana and 2 more
Heliyon
People living in developing countries are exposed to hepato-renal injuries induced by heavy metals like lead (Pb), cadmium (Cd), and mercury (Hg) since drinking water supplied is often polluted with a high concentration of those metals. Accordingly, it is necessary to search for antidotes against heavy metals poisoning. Hence, medicinal plants bearing anti-hepatotoxic properties represent a credible option; and such plant is Khaya grandifoliola . However, there is a paucity of knowledge regarding its protective effect on heavy metals-induced hepato-renal toxicity. Thus, this study was designed to assess the protective effect of the hydro-ethanolic stem bark extract of K. grandifoliola (HKG) against hepato-renal injuries induced by chronic consumption of drinking water containing high contents of Pb, Cd, and Hg; in addition to the investigation of the chemical antioxidant properties of HKG. For the antioxidant assays, HKG was tested as a potential inhibitor of lipid peroxidation, reducer of ferric and phosphomolybdenum, and scavenger of hydroxyl and 2,2- Diphenyl-Picryl-Hydrazyl radicals. Its protective effects were evaluated by daily co-treating rats with heavy metals solution (10 mL/kg b.w) containing 0.9, 0.58, and 1.13 ppm respectively for Pb, Cd and Hg and HKG (25 or 100 mg/kg b.w) for five consecutive months; and biochemical parameters associated to liver and kidneys functions, oxidative stress and metals bioaccumulation were assessed. HKG displayed a strong antioxidant capacity (IC50/EC50 range 3.95–17.17 μg/mL) correlated to its polyphenols content and comparable to that of Ascorbic acid. Serum levels of alkaline phosphatase, alanine/aspartate aminotransferase, and creatinine; renal and hepatic content of Cd and Pb, malondialdehyde and glutathione, activities of superoxide dismutase and catalase showed the protective effect of HKG, further evidenced by histopathological analysis. Taking together, these results demonstrated that HKG alleviates heavy metals-induced hepato-renal injuries in rats by reducing oxidative stress and metals-bioaccumulation.
Brice Ayissi Owona, Frédéric Nico Njayou, Pierre Mkounga, Paul Fewou Moundipa
In Silico Pharmacology
Frédy Brice Simo Nemg, Saikat De, Supriya Suman Keshry, Prabhudutta Mamidi, Frédéric Nico Njayou, Maurice Demanou and 2 more
Journal of Ethnopharmacology
Fredy Brice Nemg Simo, Saikat De, Supriya Suman Keshry, Prabhudutta Mamidi, Frédéric Nico Njayou, Maurice Demanou and 2 more
SSRN Electronic Journal
Ella Fils Armand, Manjula Shantaram, Simon Ngamli Fewou, Frédéric Nico Njayou, Sayali Chandrashekhar Deolankar, Prashant Kumar Modi and 1 more
International Journal of Phytomedicine
Alzheimer’s disease (AD) belongs to the class of neurodegenerative disorder and is biochemically characterized by amyloid-β (Aβ) plaques deposition, accumulation of neurofibrillary tangles (NFTs) accumulation and ultimately neuronal loss. Even though, the progress made in developing efficient AD therapy, there is no effective drug capable to stop and/or slow down AD progression. In the current article, we investigated the neuroprotective effect of Khaya grandifololia crude extract and fraction 2 against Aβ 42 -induced cytotoxicity and hyperphosphorylation of tau protein in differentiated neuronal cells (IMR32). Reactive oxygen species production, apoptosis and mitochondrial dynamics and function, synaptic protein, and tau phosphorylation were evaluated using fluorescence microscopy and immunoblotting. Cell viability was assessed using the MTT assay. Findings revealed that exposure of differentiated IMR32 cells to Aβ 42 alone induced the impairment of mitochondrial dynamics, decrease synaptic protein expression and increase hyperphosphorylation of tau protein (phospho tau181). In contrast, the presence of crude extract and KGf2 significantly inhibited the cleavage of Caspase-3 activation. In addition, the levels of synaptic proteins (Symptosomal associated protein 25 and Synaptosin) and superoxide dismutase were restored upon treatment with crude extract and fraction 2. Hyperphosphorylation of tau protein (Thr181) and ERK (Thr202/Tyr205) activities were also significantly reduced after treatment with crude extract and fraction 2. Our findings suggest that KG extract is a potential source for candidate drug against AD and may contribute to the development of efficient therapeutic strategy against AD.
Corinne Raïssa Ngnameko, Lucia Marchetti, Barbara Zambelli, Antonio Quotadamo, Davide Roncarati, Davide Bertelli and 5 more
Antibiotics
The medicinal plant Spathodea campanulata P. Beauv. (Bignoniaceae) has been traditionally applied for the prevention and treatment of diseases of the kidney and urinary system, the skin, the gastrointestinal tract, and inflammation in general. The present work shows for the first time how chemical components from this plant inhibit Helicobacter pylori growth by urease inhibition and modulation of virulence factors. The crude extract and the main fractions of S. campanulata bark were tested on H. pylori isolated strains and the active ones were further fractionated. Fractions and sub-fractions of the plant crude extract were characterized by ultra-high-performance liquid chromatographic tandem high resolution-mass spectrometry detection (UHPLC-HRMS). Several phenolics and triterpenoids were identified. Among the sub-fractions obtained, SB2 showed the capacity to inhibit H. pylori urease in a heterologous bacterial model. One additional sub-fraction (SE3) was able to simultaneously modulate the expression of two adhesins (HopZ and BabA) and one cytotoxin (CagA). The flavonol kaempferol was identified as the most interesting compound that deserves further investigation as a new hit for its capacity to modulate H. pylori virulence factors.
André-Ledoux Njouonkou, Sandrine Appolonie Balla Ekobo, Frédéric Nico Njayou, Olivier Raspé, Paul Fewou Moundipa, Jérôme Degreef
Czech Mycology
Termitomyces species are among the most utilised mushrooms in tropical Africa and Asia, with some species having putative medicinal properties. However, data on their diversity, distribution, ethnomycology, biological activities and metabolites are still to be completed, especially in central Africa. During field surveys in the Western Highlands of Cameroon, basidiomes of a species of this fungal genus were collected and morphologically described. The extracts were used to screen and measure some antioxidant compounds and their respective activities, including polyphenols, flavonoids, thiols, DPPH radicals scavenging activity, ferric reducing power (FRAP) and the superoxide dismutase-like (SOD-like) activity in comparison to that of vitamin C. Morphological features allowed identifying this fungal species as Termitomyces reticulatus , which is here reported for the first time from Cameroon. This species is used by locals as food. Mycochemical antioxidant analyses revealed polyphenols as the major antioxidant compounds, followed by flavonoids and thiols. Extracts also showed significant DPPH, FRAP and SOD-like activities, although less strongly than those of vitamin C. The global antioxidant potential of this species is comparable to that of many mushroom species, such as T. heimii and T. microcarpus . Extensive work on other metabolites and biological activities of T. reticulatus are needed for a better description of its potential health benefits, especially in the fight against various human oxidative stress-related diseases.
Arnaud Fondjo Kouam, Fei Yuan, Frédéric Nico Njayou, Hongtao He, Romeo Fouemene Tsayem, Babayemi Olawale Oladejo and 3 more
Frontiers in Pharmacology
Drug-induced liver injury (DILI) is a major clinical problem where natural compounds hold promise for its abrogation. Khaya grandifoliola (Meliaceae) is used in Cameroonian traditional medicine for the treatment of liver related diseases and has been studied for its hepatoprotective properties. Till date, reports showing the hepatoprotective molecular mechanism of the plant are lacking. The aim of this study was therefore to identify compounds from the plant bearing hepatoprotective activity and the related molecular mechanism by assessing their effects against acetaminophen (APAP)-induced hepatotoxicity in normal human liver L-02 cells line. The cells were exposed to APAP (10mM) or co-treated with phytochemical compounds (40 μM) over a period of 36h and, biochemical and molecular parameters assessed. Three known limonoids namely 17-epi-methyl-6-hydroxylangolensate, 7-deacetoxy-7-oxogedunin and deacetoxy-7R-hydroxygedunin were identified. The results of cells viability and membrane integrity, reactive oxygen species generation and lipid membrane peroxidation assays, cellular glutathione content determination as well as expression of cytochrome P450 2E1 demonstrated the protective action of the limonoids. Immunoblotting analysis revealed that limonoids inhibited APAP-induced c-Jun N-terminal Kinase phosphorylation (p-JNK), mitochondrial translocation of p-JNK and Bcl2-associated X Protein, and the release of Apoptosis-inducing Factor into the cytosol. Interestingly, limonoids increased the expression of Mitogen-activated Protein Kinase Phosphatase (Mkp)-1, an endogenous inhibitor of JNK phosphorylation and, induced the nuclear translocation of Nuclear Factor Erythroid 2-related Factor-2 (Nrf2) and decreased the expression of Kelch-like ECH-associated Protein-1. The limonoids also reversed the APAP-induced decreased mRNA levels of Catalase, Superoxide Dismutase-1, Glutathione-S-Transferase and Methionine Adenosyltransferase-1A. The obtained results suggest that the isolated limonoids protect L-02 hepatocytes against APAP-induced hepatotoxicity mainly through increase expression of Mkp-1 and nuclear translocation of Nrf2. Thus, these compounds are in part responsible of the hepatoprotective activity of K. grandifoliola and further analysis including in vivo and toxicological studies are needed to select the most potent compound that may be useful as therapeutic agents against DILI.
Borris Rosnay Galani Tietcheu, Marie-Emmanuelle Sahuc, Gabriele Sass, Frédéric Nico Njayou, Christine E. Loscher, Pierre Mkounga and 6 more
Archives of Virology
Borris Rosnay Galani Tietcheu, Marie-Emmanuelle Sahuc, Frédéric Nico Njayou, Gaspard Deloison, Pierre Mkounga, William F. Feudjou and 5 more
Frontiers in Microbiology
According to some recent studies, Cameroon is one of the sub-Saharan African countries most affected by hepatitis C, with low access to the standard therapy based on the combination of pegylated interferon and ribavirin. A first ethnobotanical survey, conducted in the Western region of Cameroon, reported the use of several medicinal plants in traditional medicine for the healing of liver-related disorders. Crude organic extracts of five plants surveyed were prepared and their effect against hepatitis C virus (HCV) infection investigated. The HCV JFH1 strain cell culture system HCVcc was used. The antiviral activity was quantified by immunofluorescent labeling of HCV E1 envelope protein at 30 h post-infection in the presence of the plant extracts. Active compounds were then tested in time course infection experiments. Dose-response and cellular toxicity assays were also determined. Three extracts, methanol extracts from roots of Trichilia dregeana, stems of Detarium microcarpum and leaves of Phragmanthera capitata, showed anti-HCV activity, with half-maximal inhibitory concentration of 16.16, 1.42, and 13.17 μg/mL, respectively. Huh-7 cells were incubated with the extracts for 72 h and it appears that T. dregeana extract is not toxic up to 200 μg/mL, D. microcarpum up to 100 μg/mL and P. capitata up to 800 μg/mL. All the three extracts showed a strong inhibition of HCV entry and no effect on replication or secretion. Taken together, these results showed that extracts from Cameroonian medicinal plants are promising sources of anti-HCV agents.
Armelle Tontsa Tsamo, Pierre Mkounga, Frédéric Nico Njayou, José E. Manautou, Kirk Marat, Philip G. Hultin and 1 more
Chemical and Pharmaceutical Bulletin
Three new limonoids, rubescins A-C (1-3), and three known compounds including, havanensin type limonoid TS3 (4), β-sitosterol, and stigmasterol were isolated from the root bark of Trichilia rubescens. Their structures were elucidated by means of extensive spectroscopic analyses, particularly one dimensional (1D)- and 2D-NMR techniques in conjunction with mass spectrometry. Rubescins A-C (1-3) and limonoid TS3 (4) were evaluated for their protective effects against oxidative stress induced in HC-04 cells by H2O2. Compound (1) showed strong inhibitory effects on lactase dehydrogenase (LDH) leakage, being as active (IC50 value of 0.0026 µM) as the positive control quercetin (IC50 value of 0.0030 µM).
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