BCH
Chargé de Cours
Activité scientifique
Profil chercheur
Enseignant-chercheur à l’Université de Yaoundé I. Grade : Chargé de Cours.
Publications scientifiques
Joseph Tchamgoue, Gesquière Laure M. Tiani, Bienvenu Tsakem, Brice Rostan Pinlap, Aude Ngueguim Dougue, Ondelle Laetitia Nzokou Ngoppa et 3 autre(s)
Biochemical Systematics and Ecology
Omer Bébé Ngouateu, Racéline Kamkumo Gounoue, Paul Keilah Lunga, Ulrich Kévin Kento Temfack, Léon Daniel Kede Kede, Albert Donatien Atsamo et 4 autre(s)
The Scientific World JOURNAL
BACKGROUND: In endemic countries, people remain at risk of contracting both malaria and typhoid concurrently. Though experimental animal models are very reliable for understanding human diseases, the rat model for Plasmodium-Salmonella coinfection remains underresearched. OBJECTIVES: The present study was performed to characterize the rat model of malaria-typhoid coinfection focusing on physical, hematological, and biochemical parameters. METHODS: Thirty-four Wistar rats were distributed into five groups including normal control, immunosuppressed, Salmonella-infected, Plasmodium-infected, and Salmonella-Plasmodium-coinfected. Physical signs, mobility, and the fecal appearance of animals were observed. Plasmodium load was monitored through microscopic Giemsa-staining thin blood smears. Concurrently, Salmonella load was evaluated after feces culture in Shigella-Salmonella agar medium based on the McFarland turbidity to determine the number of colony-forming units. Hematological and biochemical parameters were assessed using an automatic hematology analyzer and a spectrophotometer, respectively. RESULTS: All the infected animals exhibited at least one clinical sign including piloerection, eye depigmentation, or hyperthermia. Coinfected animals showed severe anemia, leukocytosis, and thrombocytosis compared with monoinfected animals. A significant (p < 0.001) drop in total blood proteins and cholesterol levels was observed in infected rats, with a remarkable decrease in Salmonella-Plasmodium-coinfected rats, whereas transaminase levels significantly (p < 0.001) increased in the same coinfected group. CONCLUSION: This model provides many important features of Salmonella and Plasmodium sequential coinfection and therefore may be used as a tool to better understand, diagnose, and care for human malaria and/or typhoid pathogenesis.
Lamere Martial Litchang, Brigitte Ndemangou, Branly-Natalien Nguena-Dongue, Blandine Marlyse Wache Ouahouo, Paul Keilah Lunga, Pierre Mkounga et 4 autre(s)
Figshare
Chemical investigation of the methanolic extract from the twigs of <i>Sclerocroton cornutus</i> (Pax) led to the isolation of one new rosane diterpene-type derivative named <b>Sapirosanic acid</b> (<b>1</b>) along with nine known compounds including: xylopic acid (<b>2</b>), 3,3′-di-O-methylellagic acid (<b>3</b>), 3-3′-di-O-methyl ellagic acid-4’-O-α-L-rhamnose (<b>4</b>), ursolic acid (<b>5</b>), (20 R)-cholest-4-en-3-one (<b>6</b>), a mixture of stigmasterol (<b>7</b>) and <i>ß</i>-sitosterol (<b>8</b>) and a mixture of <i>ß</i>-sitosterol-3-O-<i>ß</i>-glucopyranoside (<b>9</b>) and stigmasterol-3-O-<i>ß</i>-glucopyranoside (<b>10</b>). The structures of these compounds were elucidated by the interpretation of 1D and 2D NMR spectroscopy, electrospray ionisation mass spectrometry (ESI-MS), and comparison with literature data. Using microdilution methods, the crude extract, fractions and isolated compounds were evaluated <i>in vitro</i> for their antibacterial activities against three multidrug-resistant <i>Staphylococcus aureus</i> strains and one clinical isolate. Additionally, fractions were assayed for their antioxidant properties using 2,2’-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and Ferric reducing antioxidant power (FRAP) methods. The results of all these assays will also be discussed.
Lamere Martial Litchang, Brigitte Ndemangou, Branly-Natalien Nguena-Dongue, Blandine Marlyse Wache Ouahouo, Paul Keilah Lunga, Pierre Mkounga et 4 autre(s)
Figshare
Chemical investigation of the methanolic extract from the twigs of <i>Sclerocroton cornutus</i> (Pax) led to the isolation of one new rosane diterpene-type derivative named <b>Sapirosanic acid</b> (<b>1</b>) along with nine known compounds including: xylopic acid (<b>2</b>), 3,3′-di-O-methylellagic acid (<b>3</b>), 3-3′-di-O-methyl ellagic acid-4’-O-α-L-rhamnose (<b>4</b>), ursolic acid (<b>5</b>), (20 R)-cholest-4-en-3-one (<b>6</b>), a mixture of stigmasterol (<b>7</b>) and <i>ß</i>-sitosterol (<b>8</b>) and a mixture of <i>ß</i>-sitosterol-3-O-<i>ß</i>-glucopyranoside (<b>9</b>) and stigmasterol-3-O-<i>ß</i>-glucopyranoside (<b>10</b>). The structures of these compounds were elucidated by the interpretation of 1D and 2D NMR spectroscopy, electrospray ionisation mass spectrometry (ESI-MS), and comparison with literature data. Using microdilution methods, the crude extract, fractions and isolated compounds were evaluated <i>in vitro</i> for their antibacterial activities against three multidrug-resistant <i>Staphylococcus aureus</i> strains and one clinical isolate. Additionally, fractions were assayed for their antioxidant properties using 2,2’-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and Ferric reducing antioxidant power (FRAP) methods. The results of all these assays will also be discussed.
Lamere Martial Litchang, Brigitte Ndemangou, Branly-Natalien Nguena-Dongue, Blandine Marlyse Wache Ouahouo, Paul Keilah Lunga, Pierre Mkounga et 4 autre(s)
Natural Product Research
Chemical investigation of the methanolic extract from the twigs of Sclerocroton cornutus (Pax) led to the isolation of one new rosane diterpene-type derivative named Sapirosanic acid (1) along with nine known compounds including: xylopic acid (2), 3,3′-di-O-methylellagic acid (3), 3-3′-di-O-methyl ellagic acid-4’-O-α-L-rhamnose (4), ursolic acid (5), (20 R)-cholest-4-en-3-one (6), a mixture of stigmasterol (7) and ß-sitosterol (8) and a mixture of ß-sitosterol-3-O-ß-glucopyranoside (9) and stigmasterol-3-O-ß-glucopyranoside (10). The structures of these compounds were elucidated by the interpretation of 1D and 2D NMR spectroscopy, electrospray ionisation mass spectrometry (ESI-MS), and comparison with literature data. Using microdilution methods, the crude extract, fractions and isolated compounds were evaluated in vitro for their antibacterial activities against three multidrug-resistant Staphylococcus aureus strains and one clinical isolate. Additionally, fractions were assayed for their antioxidant properties using 2,2’-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and Ferric reducing antioxidant power (FRAP) methods. The results of all these assays will also be discussed.
Vincent Ngouana, Jean Polidor Nguetsa Demafo, Boniface Pone Kamdem, Brice Rostan Pinlap, Raoul Kemzeu, Simionne Lapoupée Kuitcha Tonga et 4 autre(s)
Asian Journal of Research in Infectious Diseases
Background: Bacteria affecting the cutaneous-digestive and oral spheres, causing pain, inflammation and sometimes serious complications such as septicemia, are exacerbated by the emergence of new antibiotic-resistant strains. The World Health Organization (WHO) encourages the use of medicinal plants to treat diseases caused by antibiotic-resistant pathogens; however, this practice should be supported by a proper scientific validation. Objective: This study sought to evaluate in vitro antibacterial, anti-inflammatory and antioxidant activities of extracts from Commelina benghalensis and Senna alata. The crude extracts from C. benghalensis and S. alata by maceration in ethanol. This was followed by a liquid-liquid partitioning of the extracts using hexane, ethyl acetate and n-butanol to yield respective fractions. The as prepared extracts and fractions were evaluated for antibacterial activity against a panel of bacteria, such as Escherichia coli (reference strain) and S. aureus CPC, E. coli CPC, E. faecalis and S. mutans (3 clinical isolates) using a broth microdilution method. The phytochemical screening of C. benghalensis and S. alata extracts were determined using standard protocols. Antioxidant and anti-inflammatory effects of extracts were assessed using standard methods. The acute toxicity of the most promising antibacterial extract was performed according to the Organisation for Economic Co-operation and Development (OECD)’s guideline, protocole number 423. Results: The yields of extraction for the ethanol extracts from C. benghalensis and S. alata were found to be 4.94% and 10.25%, respectively. The plant extracts were found to be rich in flavonoids, terpenoids and steroids, and phenolics. The plant extracts exhibited antibacterial activity with minimum inhibitory concentrations (MICs) ranging from 0.3125 to 2.5 mg/mL. Irrespective of the protocol used, the extracts displayed significant antioxidant activity with mean radical scavenging concentrations (SC50s) ranging from 30.09 to 500 µg/mL. The plant extracts revealed anti-inflammatory activity with mean inhibitory concentration (IC50) values ranging from 24.9 to 113.1 µg/mL. Upon acute toxicity study, the median lethal dose (LD50) of the most promising antibacterial extract was found to be greater than 2000 mg/kg. Conclusion: This study demonstrates antibacterial, anti-inflammatory and antioxidant activities of extracts C. benghalensis and S. alata, thus validating the traditional use of these plants in treating infectious diseases.
Yanick Kevin Melogmo Dongmo, Mariscal Brice Tchatat Tali, Darline Dize, Cedric Derick Jiatsa Mbouna, Sorelle Kache Fotsing, Vincent Ngouana et 7 autre(s)
Journal of Ethnopharmacology
Audrey Carrel Nguelo Talla, Eugenie Aimée Madiesse Kemgne, Vincent Ngouana, Bijou-Lafortune Noumboue Kouamou, Listone Monelle Nzeye Ngameni, Brice Rostan Pinlap et 5 autre(s)
Preprints.org
Shigellosis is a pathological condition that affects the digestive system to possibly cause diarrhoea. Shigella species, which are responsible for this disease, are highly contagious and spread through contaminated food and water. The increasing development of resistance by Shigella species necessitate the urgent need to search for new therapies against shigellosis causing diarrhoea. The scientific validation of medicinal plants, such as Diospyros gilletii, which is used for the traditional treatment of diarrhoeal conditions is worthwhile. The present study aims to investigate the antibacterial activity of extracts from D. gilletii against selected Shigella species. Extracts from D. gilletii stem bark were prepared by maceration using various solvents. An-tibacterial activity of D. gilletii extracts was evaluated on Shigella dysenteriae, S. flexneri, S. boydii, and S. sonnei using a microdilution method, whereas cytotoxicity test was performed on Vero and Raw cells using resazurin-based colorimetric assay. Bacterial membrane permeability studies were evaluated using pro-pidium iodide (PI) and 1-N-phenylnaphthylamine (NPN) uptake assays, whereas inhibition and eradica-tion tests on bacterial biofilms were carried out by spectrophotometry. As a result, methanol, ethanol and hydroethanol extracts of D. gilletii inhibited the growth of S. boydii, S. flexneri and S. sonnei with MIC values ranging from 125 to 500 µg/mL, without toxicity to Vero and Raw cells. Time kill kinetics revealed bacteri-cidal orientation at 2MIC and 4MIC, and bacteriostatic outcome at 1/2MIC. The mechanistic basis of anti-bacterial action revealed that D. gilletii extracts inhibited and eradicated Shigella biofilms, and promoted the accumulation of NPN and PI within the inner and outer membrane of bacteria to increase membrane per-meability, thereby causing membrane damage. This novel contribution toward the antibacterial and mech-anisms of action of D. gilletii extracts against Shigella species substantiate the use of this plant in the tradi-tional treatment of infectious diarrhoea.
Franklin Loïc Tchinda Taghu, Boniface Pone Kamdem, Vincent Ngouana, Zuriatou Yajeh Tanka, Victorine Lorette Yimgang, Julius Nsami Ndi et 2 autre(s)
Drugs and Drug Candidates
The development of antimicrobial resistance has increased the prevalence of infectious diseases, causing a global health problem that accounts for over 4.95 million deaths worldwide annually. The side effects associated with current antibiotics prompt a crucial need to search for effective and safe antimicrobial agents. In this study, silver nanoparticles (AgNPs) were prepared by chemical reduction method using silver nitrates as a metallic precursor and Croton macrostachyus bark aqueous extract as a reducing and capping agent. The nanoparticles were further functionalized using C. macrostachyus-based activated carbon (CAC) to generate nanocomposites (CAC-AgNPs). The nanomaterials were characterized by ultraviolet-visible (UV–vis) absorption spectra and Fourier transform infrared (FTIR) spectra. The antibacterial activity of the as-prepared nanomaterials was evaluated against an array of bacterial strains by microdilution method, whereas their cytotoxicity profile was evaluated using Vero cells (human mammalian cells). Antibacterial mechanistic studies of active nanomaterials were carried out through bacterial growth kinetics, nucleic acid leakage tests, and catalase inhibition assays. As a result, the as-prepared nanomaterials exhibited antibacterial activity against an array of bacterial strains (minimum inhibitory concentration (MIC) range: 62.5 to 500 µg/mL), the most susceptible being Escherichia coli and Staphylococcus aureus. Cytotoxicity studies of the nanomaterials on Vero cells revealed that the nanocomposite (median cytotoxic concentration (CC50): 213.6 µg/mL) was less toxic than its nanoparticle (CC50 value: 164.75 µg/mL) counterpart. Antibacterial mechanistic studies revealed that the nanomaterials induced (i) bacteriostatic activity vis à vis E. coli and S. aureus and (ii) inhibition of catalase in these bacteria. This novel contribution regarding the antibacterial mechanisms of action of silver nanocomposites from C. macrostachyus-based activated carbon may contribute to our understanding of the antibacterial action of these biomaterials. Nevertheless, more chemistry and in vivo experiments as well as in depth antibacterial mechanistic studies are warranted for the successful utilization of these antibacterial biomaterials.
Yvan Anderson Ngandjui Tchangoue, Joseph Tchamgoue, Paul Keilah Lunga, Janosch Knepper, Ramona Păltinean, Kerstin Ibrom et 4 autre(s)
Fitoterapia
Fred Djague, Paul Keilah Lunga, Rufin Marie Kouipou Toghueo, Yanick Kevin Dongmo Melogmo, Boyom Fabrice Fekam
PLoS ONE
Drug resistant Salmonella species and shortcomings related to current drugs stress the urgent need to search for new antimicrobial agents to control salmonellosis. This study investigated the antisalmonellal and antioxidant potentials of methanolic and hydro-ethanolic extracts of Garcinia kola and Alchornea cordifolia as potential sources of drugs to control Salmonella species and to reduce related oxidative stress. The antisalmonellal activity was assessed using the broth microdilution, membrane destabilization and time-kill kinetic assays. While, the DPPH, ABTS and FRAP assays were used for the determination of the antioxidant activities. The minimum inhibitory concentrations ranged from 125 to 1000 μg/mL, with the methanolic root extract of G. kola being the most active. The time kill kinetic assay revealed a concentration-dependent bacteriostatic activity for promising extracts. Potent extracts from G. kola showed the ability to destabilize S. typhi outer membrane, with the methanolic root extract presenting the highest activity; two-fold higher than those of polymyxin B tested as reference. In addition, this methanolic root extract of G. kola also provoked nucleotide leakage in a concentration-dependent manner. From the antioxidant assays, the hydro-ethanolic extract from the stem bark of A. cordifolia presented significant activities comparable to that of Vitamin C. The methanolic root extract of G. kola also presented appreciable antioxidant activities, though less than that of A. cordifolia. Overall, the phytochemical screening of active extracts revealed the presence of anthocyanins, flavonoids, glycosides, phenols, tannins, triterpenoids and steroids. These results provide evidence of the antibacterial potential of G. kola and offer great perspectives in a possible standardisation of an antisalmonellal phytomedicine.
Donatien Gatsing, Paul Keilah Lunga, Joseph M.M. Nkodo, Jean‐De‐Dieu Tamokou, Jules‐Roger Kuiate, Joseph Tchoumboué
Pharmacologia
Background and Objective: Paullinia pinnata is an African woody vine whose leaf decoction has been used in Cameroon for the treatment of bacterial infections like typhoid fever, syphilis, gonorrhea, diarrhoea and symptoms such as stomach-ache and waist pain. The present study was designed to evaluate the adverse side effects resulting from the use of P. pinnata methanol leaf extract in the treatment of Salmonella typhimurium-induced typhoid in Wistar rats. Methodology: After the establishment of infection by oral administration of a S. typhimurium suspension, animals were treated by the daily administration of P. pinnata methanol leaf extract at various doses (55. 75, 111.50, 223 and 446 mg kgG 1 b.wt.). The effect of the extract on body weight evolution was monitored daily. Results: Also, the effect of the extract on relative organ weight, biochemical parameters as well as liver histology was assessed. Irrespective of sex, typhoid fever induced an abnormal increase in the relative weight of most vital organs of toxicological importance. However, extract treatment normalized the excessive increase in relative organ weights; while inducing a significant (p<0.05) body weight gain in a dose-dependent manner. The level of liver enzymes (ALT and AST) were significantly (p<0.05) reduced after the treatment of the animals with P. pinnata leaf extract. The histopathological analysis of the liver revealed that extract treatment greatly reduced the degree of liver affections in a dose-dependent manner. However, at high doses (dose $223 mg kgG 1 b.wt.) the extract was capable of stimulating hepatic necrosis.
Xing‐Wei Yang, Xu‐Jie Qin, Yun‐Li Zhao, Paul Keilah Lunga, Xiao‐Nian Li, Shizhi Jiang et 3 autre(s)
Tetrahedron Letters
Paul Keilah Lunga, Xu‐Jie Qin, Xing Yang, Jules‐Roger Kuiate, Zhi Zhi Du, Donatien Gatsing
BMC Complementary and Alternative Medicine
BACKGROUND: Paullinia pinnata L. (Sapindaceae) is an African woody vine, which is widely used in traditional medicine for the treatment of human malaria, erectile dysfunction and bacterial infections. A phytochemical investigation of its methanol leaf and stem extracts led to the isolation of seven compounds which were evaluated for their antimicrobial properties. METHODS: The extracts were fractionated and compounds were isolated by chromatographic methods. Their structures were elucidated from their spectroscopic data in conjunction with those reported in literature. The antimicrobial activities of the crude extracts, fractions and compounds were evaluated against bacteria, yeasts and dermatophytes using the broth micro-dilution technique. RESULTS: Seven compounds: 2-O-methyl-L-chiro-inositol (1), β-sitosterol (2), friedelin (3), 3β-(β-D-Glucopyranosyloxy) stigmast-5-ene (4), (3β)-3-O-(2'-Acetamido-2'-deoxy-β-D-glucopyranosyl) oleanolic acid (5), (3β,16α-hydroxy)-3-O-(2'-Acetamido-2'-deoxy-β-D-glucopyranosyl) echinocystic acid (6) and (3β)-3-O-[β-D-glucopyranosyl-(1″-3')-2'-acetamido-2'-deoxy-β-D-galactopyranosyl]oleanolic acid (7) were isolated. Compounds 5 and 7 showed the best antibacterial and anti-yeast activities respectively (MIC value range of 0.78-6.25 and 1.56-6.25 μg/ml), while 6 exhibited the best anti-dermatophytic activity (MIC value range of 6.25-25 μg/ml). CONCLUSION: The results of the present findings could be considered interesting, taking into account the global disease burden of these susceptible microorganisms, in conjunction with the search for alternative and complementary medicines.
Guy Sedar Singor Njateng, Donatien Gatsing, Raymond Simplice Mouokeu, Paul Keilah Lunga, Jules‐Roger Kuiate
BMC Complementary and Alternative Medicine
BACKGROUND: During the last decades, the number of people suffering from dermatophytoses has seriously increased, mainly due to the development of resistant strains of microorganisms to a range of formally efficient antibiotics. Polyscias fulva, a medium size tree which grows in the West Region of Cameroon is traditionally used for local application against dermatoses and orally against venereal infections. The dichloromethane-methanol (1:1 v/v) extract from the stem bark of Polyscias fulva was evaluated for its in vitro and in vivo antifungal activities. METHODS: The plant extract was prepared by maceration of its stem bark powder in CH(2)Cl(2)-MeOH (1:1 v/v). The extract obtained was successively partitioned in hexane, ethyl acetate and n-butanol. Phytochemical screening was performed using standard methods. In vitro antidermatophytic activity was assayed by the well diffusion and broth microdilution methods. The degree of dermal irritation of the crude extract was determined in guinea pigs using the occluded dermal irritation test method. The in vivo antidermatophytic activity of the extract-oil formulation (1.25, 2.5 and 5% w/w concentrations) was evaluated using Trichophyton mentagrophytes-induced dermatophytosis in a guinea pigs model. RESULTS: Phytochemical screening indicated that, the crude extract, ethyl acetate, n-butanol and residue fractions contain in general saponins, tannins, alkaloids, anthraquinones and phenols while the hexane fraction contains only alkaloids. The ethyl-acetate, n-butanol and residue fractions displayed higher antifungal activities (MIC = 0.125-0.5 mg.mL(-1)) against eight dermatophytes as compared to the crude extract (MIC = 0.5-1 mg.mL(-1)). This latter appeared to have slight perceptible erythema effects on guinea pigs as the primary irritation index (PII) was calculated to be 0.54. In vivo, the antidermatophytic activities of the extract-oil formulations were dose-dependent. Griseofulvin-oil 5% at 0.01 g/kg and formulated extract-oil (5%) at 0.1 g/kg eradicated the microbial infection after thirteen and fourteen days of daily treatment respectively. CONCLUSIONS: The results of preclinical in vitro and in vivo evaluations indicate that the extract-oil formulation at 5% may constitute an alternative means to alleviate fungal infections caused by dermatophytes.
Patricia Djuissi Tchakam, Paul Keilah Lunga, Théodora Kopa Kowa, Antoine Honoré Nkuete Lonfouo, Hippolyte K. Wabo, Léon Azefack Tapondjou et 2 autre(s)
BMC Complementary and Alternative Medicine
BACKGROUND: Psorospermun aurantiacum and Hypericum lanceolatum are plants locally used in Cameroon and other parts of Africa for the treatment of gastrointestinal and urinary tract infections, skin infections, venereal diseases, gastrointestinal disorder, infertility, epilepsy as well as microbial infections. The present study was designed in order to investigate the in vitro antimicrobial and radical scavenging activities of the extracts and isolated compounds from the leaves of these plants. METHODS: The plant extract was prepared by maceration in ethyl acetate and methanol and fractionated by column chromatography. The structures of isolated compounds were elucidated by spectroscopic analyses in conjunction with literature data. The broth microdilution method was used to evaluate the in vitro antimicrobial activity against bacteria, yeasts and dermatophytes. The antioxidant potentials of the extracts and their isolated compounds were evaluated using the DPPH radical scavenging method. RESULTS: Five known compounds: physcion (1), 1,8-dihydroxy-3-geranyloxy-6-methylanthraquinone (2), kenganthranol B (3), vismiaquinone (4), and octacosanol (5) were isolated from the leaves of P. aurantiacum while six compounds including friedelin (6), betulinic acid (7), 2,2',5,6'-tetrahydroxybenzophenone (8), allanxanthone A (9), 1,3,6- trihydroxyxanthone (10) and isogarcinol (11) were isolated from H. lanceolatum. Compound 8 and 4 exhibited the highest antibacterial and antifungal activities with MIC ranges of 2-8 μg/ml and 4-32 μg/ml respectively. P. aurantiacum crude extract (Rsa50 = 6.359 ± 0.101) showed greater radical scavenging activity compared with H. lanceolatum extract (Rsa50 = 30.996 ± 0.879). Compound 11 showed the highest radical scavenging activity (RSa50 = 1.012 ± 0.247) among the isolated compounds, comparable to that of L-arscobic acid (RSa50 = 0.0809 ± 0.045). CONCLUSIONS: The experimental findings show that the ethyl acetate and methanol extracts and isolated compounds from P. aurantiacum and H. lanceolatum stem bark possess significant antimicrobial and antioxidant activities justifying the use of these plants in traditional medicine, which may be developed as phytomedicines.
Raymond Simplice Mouokeu, Rosalie A.N. Ngono, Paul Keilah Lunga, Martin M Koanga, Alambert T Tiabou, Guy SS Njateng et 2 autre(s)
BMC Complementary and Alternative Medicine
BACKGROUND: The emergence in recent years of numerous resistant strains of pathogenic bacteria to a range of formerly efficient antibiotics constitutes a serious threat to public health. Crassocephalum bauchiense, a medicinal herb found in the West Region of Cameroon is used to treat gastrointestinal infections as well as liver disorders. The ethyl acetate extract from the leaves of C. bauchiense was evaluated for its antibacterial activity as well as acute and sub-acute toxicities. METHODS: The plant extract was prepared by maceration in ethyl acetate. Its phytochemical screening was done by standard methods. The broth microdilution method was used to evaluate the in vitro antibacterial activity. The in vivo antibacterial activity of a gel formulation (0.05, 1 and 2% w/v) of this extract was evaluated using a Staphylococcus aureus-induced dermatitis in a murine model. Selected haematological and biochemical parameters were used to evaluate the dermal sub-acute toxicity of the extract in rats. RESULTS: Phytochemical screening of the C. bauchiense extract revealed the presence of alkaloids, phenols, tannins and sterols. In vitro antibacterial activities were observed against all the tested microorganisms (MIC = 0.04-6.25 mg/ml). Formulated extract-gel (2% w/v) and gentamycin (reference drug) eradicated the microbial infection after five days of treatment. A single dermal dose of this extract up to 32 g/kg body weight (bw) did not produce any visible sign of toxicity. Also, daily dermal application of the C. bauchiense extract gel formulation for 28 days did not show any negative effect, instead some biochemical parameters such as alanine aminotransferase (ALT and AST), low density lipoprotein (LDL), high density lipoprotein (HDL) and triglycerides were significantly (p < 0.05) affected positively. CONCLUSION: These results indicate that the C. bauchiense ethyl acetate extract can be used safely for the treatment of some bacterial infections.
Marie Stéphanie Goka Chekem, Paul Keilah Lunga, Jean‐De‐Dieu Tamokou, Jules Roger Kuiaté, Pierre Tane, Gérard Vilarem et 1 autre(s)
Pharmaceuticals
The essential oil of the aerial part (leaves, flowers and stem) of Chenopodium ambrosioides was obtained by hydrodistillation and its chemical composition analyzed by GC and GC/MS, which permitted the identification of 14 components, representing 98.8% of the total oil. Major components were α-terpinene (51.3%), p-cymene (23.4%) and p-mentha-1,8-diène (15.3%). The antifungal properties of this essential oil were investigated in vitro by the well diffusion and broth microdilution methods. The in vitro antifungal activity was concentration dependent and minimum inhibitory concentration values varied from 0.25 to 2 mg/mL. The in vivo antifungal activity was evaluated on an induced vaginal candidiasis rat model. The in vivo activity of the oil on mice vaginal candidiasis was not dose-dependent. Indeed, all the three tested doses; 0.1%, 1% and 10% led to the recovery of mice from the induced infection after 12 days of treatment. The effect of the essential oil on C. albicans ATCC 1663 fatty acid profile was studied. This oil has a relatively important dose-dependent effect on the fatty acids profile.
Frank Lilian Mahel Batana, Vincent Ngouana, Eugenie Aimée Madiesse Kemgne, Boniface Pone Kamdem, Marius Jaurès Tsakem Nangap, Raoul Kemzeu et 8 autre(s)
European Journal of Medicinal Plants
Background: Malaria is a parasitic disease that affects many parts of the globe, especially sub-Saharan Africa. Over time, malaria parasites have become resistant to most antimalarial drugs, including artemisinin. Medicinal plants, which are used in the traditional treatment of malaria can afford effective drugs against this notorious disease. One such plant includes Vernonia blumeoides, which is used in the treatment of parasitic diseases, including malaria. Thus the scientific validation of the use of Vernonia blumeoides in ethnomedicine is of outstanding importance. Objectives: This study sought to investigate the antiplasmodial and antioxidant activity of extracts from Vernonia blumeoides. Methods: Vernonia blumeoides ethanol extract was obtained by maceration, and then subjected to phytochemical screening using standard protocols. The as-prepared extract was partitioned using solvents of increasing polarity to afford hexane, ethyl acetate, n-butanol fractions, and the water residue. The antiplasmodial potential of extract and fractions was determined by the Sybr green method. Antioxidant activity of V. blumeoides extracts was evaluated using DPPH, ABTS and FRAP assays. Cytotoxicity test was performed on murine macrophage Raw cells using the resazurin test. Results: The ethanol extract was obtained as a brown powder and the yield of extraction was found to be 43.95%. The phytochemical screening of this extract revealed the presence of tannins, alkaloids, flavonoids, phenolic compounds, and glycosides. Upon antiplasmodial screening against P. falciparum Dd2 and 3D7, the median inhibitory concentrations (IC50) of extract and fractions from V. blumeoides ranged from 4.70 to >100 µg/ml, with ethyl acetate extract having the lowest IC50 value and highest activity. Vernonia blumeoides extracts exhibited antioxidant activity with median scavenging concentrations ranging from 31.17 to 124.1 µg/mL, 50.84 to 500 µg/mL, and 33.95 to 500 µg/mL for ABTS, DPPH and FRAP assays, respectively. Cytotoxicity test of V. blumeoides extracts on Raw cells revealed non toxicity. Conclusions: This novel contribution demonstrated the antiplasmodial activity of V. blumeoides extracts, thus validating the ethnopharmacological use of this plant in the treatment of malaria symptoms. Nonetheless, in depth studies on the mechanisms of action, in vivo toxicity, as well as pharmacokinetic experiments are warranted for the successful utilization of this plant in ethnomedicine.
Joseph Mbaku Ngoumou, Vincent Ngouana, Boniface Pone Kamdem, Natacha Paule Marie Ndzie, Brice Rostan Pinlap, Aubin Kamche Youbi et 4 autre(s)
South African Journal of Botany
Bijou-Lafortune Noumboue Kouamou, Boniface Pone Kamdem, Vincent Ngouana, Tashie Evangeline Ngwanguong, Jaurès Marius Tsakem Nangap, Listone Monelle Nzeye Ngameni et 3 autre(s)
Asian Pacific Journal of Tropical Biomedicine
Objective: To evaluate the anti-shigellosis activity of the hydroethanol extract of Diospyros gilletii (D. gilletii ) stem bark in Shigella flexneri (S. flexneri)-induced diarrheal mice. Methods: The hydroethanolic extract was obtained by maceration of D. gilletii stem bark in 70% hydroethanol (waterethanol; 30:70, v/v ) solution. Then, mice pretreated with cyclophosphamide for immunosuppression were administered orally with an inoculum containing S. flexneri , and subsequently treated with 100, 200, and 400 mg/kg of the hydroethanol extracts for 10 days. The bacterial colonies were enumerated and hematological and biochemical parameters were determined. Serum pro-inflammatory mediators including IL-1β, IL-18, and TNF-α, and nitric oxide levels were quantified by ELISA. Histological analyses of the kidney, liver, and colon were also conducted. Results: Treatment with 200 and 400 mg/kg of the hydroethanolic extracts markedly inhibited the growth of S. flexneri. Moreover, treatment with D. gilletii extract downregulated the levels of IL-1β, IL-18, and TNF-α, and restored hematological and biochemical parameters as well as histological architecture of the colon, liver, and kidneys. Additionally, the oral administration of 2000 mg/kg D. gilletii extract did not induce any sign of toxicity, with a median lethal dose greater than 2000 mg/kg. Conclusions: D. gilletii extract demonstrates the anti-shigellosis effects in S. flexneri-induced diarrheal mice, supporting the traditional use of this plant in treating diarrhea.
Boniface Pone Kamdem, Jamila Aminatou Kone, Vincent Ngouana, Yolande Nzeulienou Noubissi, Aicha Sylvanie Magniteu Lekefack, Christelle Amanda Djakam Ngola et 4 autre(s)
International audience
Wilfred A. Abia, Richard N. Fomboh, Paul Keilah Lunga, Yacouba Foupouapouognigni, Aurélie Kognoudjui Mambap
Global Health Synapse
This paper explores the One Health approach as a vital framework for addressing food security and safety issues in Sub-Saharan Africa, particularly in the context of nutrition, health, and climate change. The interconnections between animal health, human health, and environmental sustainability highlight the need for integrated health policies that foster collaboration among the agriculture, health, and environmental sectors. Investment in interdisciplinary research is essential for identifying innovative and sustainable agri-food practices that can enhance regional food security. Emphasis should be placed on research initiatives that focus on sustainable agricultural methods, the development of climate-resilient crops, and effective pest management strategies, ensuring robust food systems that can adapt to the challenges of climate change. Moreover, promoting education and training is critical for empowering local farmers, healthcare professionals, and policymakers with the knowledge to implement One Health principles effectively. Educational initiatives can raise awareness of best practices in food production and handling, ultimately improving public health. Strengthening surveillance and monitoring systems is also crucial for early identifying and managing zoonotic diseases and foodborne pathogens, providing necessary data for informed decision-making. Finally, encouraging sustainable agricultural practices such as organic farming and agroecology is paramount for enhancing food safety and security. Policymakers must create incentives to support these transitions and engage communities in the decision-making processes to ensure that policies are contextually relevant. Overall, the findings emphasize the necessity of a holistic, collaborative approach to food security and safety in Sub-Saharan Africa, particularly in light of the region’s ongoing challenges related to nutrition, health, and climate change.
Manuella Chloé Fitliavom Mouanji, Vincent Ngouana, Eugenie Aimée Madiesse Kemgne, Boniface Pone Kamdem, Diane Tchuendem, Diana Sandra Wendji Monkam et 7 autre(s)
South African Journal of Botany
Branly-Natalien Nguena-Dongue, Elisabeth Zeuko’o Menkem, Paul Keilah Lunga, Stella Tofac Asong, Ayodeji Amobonye, Santhosh Pillai
Future Journal of Pharmaceutical Sciences
Abstract Background Different parts of Allanblackia floribunda, Calotropis procera, Hymenocardia acida, Irvingia gabonensis, Newbouldia laevis , and Xylopia acutiflora have been used traditionally across different parts of Cameroon to overcome infectious diseases, especially pneumonia. Hence, this study investigated the antibacterial potential of six Cameroonian medicinal plants against selected ESKAPE pathogens ( Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa) as well as Streptococcus pneumoniae . Methodology The inhibitory activities of different extracts from six Cameroonian plants against the pathogens were evaluated by determining their MICs. Subsequently, the top four bioactive plant extracts were assessed for antibiofilm activity, time-kill kinetics, cytotoxicity (Raw and Vero cell lines), as well as antioxidant activities. Finally, the effect of the most potent extract, viz. ethanolic extract of Xylopia acutiflora steam bark, on bacterial morphology was elucidated through scanning electron microscopy while its phytochemical composition was profiled using liquid chromatography–mass spectrometry (LC–MS). Results Twenty-two out of the 32 prepared extracts showed significant antibacterial activity, with MICs varying from 31.5 to 1000 µg/mL. The ethanolic, methanolic, and hydroethanolic extracts from Xylopia acutifolia and ethanolic extract from Colotropix procera exhibited broad-spectrum activity, inhibiting and eradicating bacterial biofilm. Furthermore, the extract from X. acutifolia was shown to be the most effective scavenger against DPPH (IC 50 ; 83.79 ± 1.92 µg/mL) and FRAP (IC 50 ; 22.89 ± 1.36 µg/mL) radicals, while C. procera extract was the most effective against ABTS (IC 50 ; 67.95 ± 1.83 µg/mL). The extracts were demonstrated to possess low cytotoxicity on both Raw and Vero cell lines. In addition, SEM revealed that X. acutifolia elicited cell membrane rupture and consequently cytoplasm leakage in E. coli and P. aeruginosa. Twenty-four different compounds were detected in the X. acutifolia extract via LC–MS analysis, and it was hypothesized that the recorded bioactivity in the extract might be ascribed to these compounds. Conclusion Results from this study have scientifically validated the ethnomedicinal uses of the six Cameroonian plants as therapeutics for infections with X. acutiflora ethanolic extract displaying the highest bioactivity. Thus, there is the need for further investigations into phytochemicals from these plants as they could serve as important sources of novel antioxidants and antimicrobial agents. Graphical abstract
Audrey Carrel Nguelo Talla, Eugenie Aimée Madiesse Kemgne, Vincent Ngouana, Bijou-Lafortune Noumboue Kouamou, Listone Monelle Nzeye Ngameni, Brice Rostan Pinlap et 5 autre(s)
Drugs and Drug Candidates
Shigellosis is a pathological condition that affects the digestive system and possibly causes diarrhoea. Shigella species, which are responsible for this disease, are highly contagious and spread through contaminated food and water. The increasing development of resistance by Shigella species necessitates the urgent need to search for new therapies against diarrhoea-causing shigellosis. The scientific validation of medicinal plants, such as Diospyros gilletii, which is used for the traditional treatment of diarrhoeal conditions is worthwhile. The present study aims to investigate the antibacterial activity of extracts from D. gilletii against selected Shigella species. Extracts from D. gilletii stem bark were prepared by maceration using various solvents. The antibacterial activity of D. gilletii extracts was evaluated in Shigella dysenteriae, S. flexneri, S. boydii, and S. sonnei using a microdilution method, whereas a cytotoxicity test was performed on Vero and Raw cells using resazurin-based colorimetric assays. Bacterial membrane-permeability studies were evaluated using propidium iodide (PI)- and 1-N-phenyl-naphthylamine (NPN)-uptake assays, whereas inhibition and eradication tests on bacterial biofilms were carried out by spectrophotometry. As a result, methanol, ethanol and hydroethanol (water: ethanol; 30:70, v/v) extracts of D. gilletii inhibited the growth of S. boydii, S. flexneri and S. sonnei, with minimum inhibitory concentration (MIC) values ranging from 125 to 500 µg/mL, without toxicity to Vero and Raw cells. Time-kill kinetics revealed bactericidal orientation at 2 MIC and 4 MIC and a bacteriostatic outcome at 1/2 MIC. The mechanistic basis of antibacterial action revealed that D. gilletii extracts inhibited and eradicated Shigella biofilms and promoted the accumulation of NPN and PI within the inner and outer membranes of bacteria to increase membrane permeability, thereby causing membrane damage. This novel contribution toward the antibacterial mechanisms of action of D. gilletii extracts against Shigella species substantiates the use of this plant in the traditional treatment of infectious diarrhoea.
Frank Lilian Mahel Batana, Vincent Ngouana, Eugenie Aimée Madiesse Kemgne, Boniface Pone Kamdem, Marius Jaurès Tsakem Nangap, Raoul Kemzeu et 8 autre(s)
Preprints.org
Background: Malaria is a parasitic disease that affects many parts of the globe, especially sub-Saharan Africa. Over time, malaria parasites have become resistant to most antimalarial drugs, including artemisinin. Medicinal plants, which are used in the traditional treatment of malaria can afford effective drugs against this notorious disease. One such plant includes Vernonia blumeoides, which is used in the treatment of parasitic diseases, including malaria. Thus the scientific validation of the use of Vernonia blumeoides in ethnomedicine is of outstanding importance. Objectives: This study sought to investigate the antiplasmodial and antioxidant activity of extracts from Vernonia blumeoides; Methods: Vernonia blumeoides ethanol extract was obtained by maceration, and then subjected to phytochemical screening using standard protocols. The as-prepared extract was partitioned using solvents of increasing polarity to afford hexane, ethyl acetate, n-butanol fractions, and the water residue. The antiplasmodial potential of extract and fractions was determined by the Sybr green method. Antioxidant activity of V. blumeoides extracts was evaluated using DPPH, ABTS and FRAP assays. Cytotoxicity test was performed on murine macrophage Raw cells using the resazurin test; Results: The ethanol extract was obtained as a brown powder and the yield of extraction was found to be 43.95%. The phytochemical screening of this extract revealed the presence of tannins, alkaloids, flavonoids, phenolic compounds, and glycosides. Upon antiplasmodial screening against P. falciparum Dd2 and 3D7, the median inhibitory concentrations (IC50) of extract and fractions from V. blumeoides ranged from 4.70 to &amp;gt;100 µg/ml, with ethyl acetate extract having the lowest IC50 value and highest activity. Vernonia blumeoides extracts exhibited antioxidant activity with median scavenging concentrations ranging from 31.17 to 124.1 µg/mL, 50.84 to 500 µg/mL, and 33.95 to 500 µg/mL for ABTS, DPPH and FRAP assays, respectively. Cytotoxicity test of V. blumeoides extracts on Raw cells revealed non toxicity; Conclusions: This novel contribution demonstrated the antiplasmodial activity of V. blumeoides extracts, thus validating the ethnopharmacological use of this plant in the treatment of malaria symptoms. Nonetheless, in depth studies on the mechanisms of action, in vivo toxicity, as well as pharmacokinetic experiments are warranted for the successful utilization of this plant in ethnomedicine.
Bijou-Lafortune Noumboue Kouamou, Boniface Pone Kamdem, Vincent Ngouana, Evangeline Tashie Ngwanguong, Marius Jaurès Tsakem Nangap, Listone Monelle Ngameni Nzeye et 3 autre(s)
SSRN Electronic Journal
Evariste Josué Momo, François Nguimatsia, Laure Ateufouet Ngouango, Paul Keilah Lunga, Boniface Pone Kamdem, Pierre Michel Jazet Dongmo
Preprints.org
Plants from the Myrtaceae family are well known to contain considerable amounts of volatile compounds, ranging from oxygenated monoterpenes to hydrogenated sesquiterpenes, and others, which exhibit antimicrobial activity. One such plant includes Syzygium aromaticum that has been extensively used to treat a number of disorders, including bacterial and fungal infections. Thus, the scientific validation of the essential oil (EO) of Syzygium aromaticum vis-&agrave;-vis Candida and Cryptococcus species is valuable. To this end, the present study sought to investigate the antifungal activity of EO from S. aromaticum (clove) leaves and flower buds against Candida and Cryptococcus species. The antioxidant activity of S. aromaticum&rsquo;s essential oils is also elucidated. The EO was extracted from fresh leaves and floral buds of S. aromaticum using a Clevenger-type apparatus. The as-prepared essential oils were further evaluated for antifungal activity against Candida and Cryptococcus species using a microdilution method. The phytochemical analysis of the EOs was assessed by gas chromatography/mass spectrometry (GC-MS). Antioxidant activities of the EOs were evaluated using standard methods. As a result, the GC-MS analysis revealed the presence of volatile compounds, such as eugenol (87.08%), &beta;-caryophyllene (6.40%) and acetyleugenol (4.45%) as the major constituents of EO from the flower buds ; and eugenol (90.54%) and &beta;-caryophyllene (24.65%) as the major components of the leaf&rsquo;s EO. The eugenol-rich essential oils exhibited significant antifungal effects against Candida species (common MIC value: 200 ppm) and Cryptococcus neoformans (MIC value: 50 ppm), as well as antioxidant activity. Overall, essential oils of S. aromaticum demonstrated an-tioxidant and antifungal effects, thus validating the ethnopharmacological use of this plant in the treatment of fungal infections. However, antifungal mechanisms of action, in-depth toxicity and in vivo experiments, and pharmacokinetics are warranted to support the use of this plant in ethnomedicine.
Evariste Josué Momo, François Nguimatsia, Laure Ateufouet Ngouango, Paul Keilah Lunga, Boniface Pone Kamdem, Pierre Michel Jazet Dongmo
Future Pharmacology
Plants from the Myrtaceae family are known to contain considerable quantities of volatile compounds, ranging from oxygenated monoterpenes to hydrogenated sesquiterpenes, and others, which exhibit antimicrobial activity. One such plant includes Syzygium aromaticum, which has been extensively used to treat a number of disorders, including bacterial and fungal infections. Thus, the scientific validation of the essential oil (EO) of Syzygium aromaticum vis-à-vis Candida and Cryptococcus species is valuable. To this end, the present study sought to investigate the antifungal activity of EO from S. aromaticum (clove) leaves and flower buds against Candida and Cryptococcus species. The antioxidant activity of S. aromaticum’s essential oils was also elucidated. The EO was extracted from fresh leaves and floral buds of S. aromaticum using a Clevenger-type apparatus. The as-prepared essential oils were further evaluated for antifungal activity against Candida and Cryptococcus species using a microdilution method. The phytochemical analysis of the EOs was assessed by gas chromatography/mass spectrometry (GC-MS). Antioxidant activities of the EOs were evaluated using standard methods. As a result, the GC-MS analysis revealed the presence of volatile compounds, such as eugenol (87.08%), β-caryophyllene (6.40%) and acetyleugenol (4.45%) as the major constituents of EO from the flower buds, and eugenol (90.54%) and β-caryophyllene (8.42%) as the major components of the leaf’s EO. The eugenol-rich essential oils exhibited significant antifungal effects against Candida species (common MIC value: 200 ppm) and Cryptococcus neoformans (MIC value: 50 ppm), as well as antioxidant activity. Overall, essential oils of S. aromaticum demonstrated antioxidant and antifungal effects, thus validating the ethnopharmacological use of this plant in the treatment of fungal infections. However, antifungal mechanisms of action, in-depth toxicity and in vivo experiments, and pharmacokinetics are warranted to support the use of this plant in ethnomedicine.
Zuriatou Yajeh Tanka, Naphtali Odogu Ankoro, Vincent Ngouana, Franklin Loïc Tchinda Taghu, Abongta Lum Mforbesi, Branly-Natalien Nguena-Dongue et 4 autre(s)
BioMed
Caused by pathogenic microorganisms, infectious diseases are known to cause high mortality rates, severe burdens of disability, and serious worldwide aftermaths. Drug-resistant pathogens have reduced the efficacy of available therapies against these diseases, thus accentuating the need to search for effective antimicrobials. Medicinal plants have served as starting material for the preparation of a number of antimicrobial agents. To this end, the present study highlights the green synthesis of Cocos nucifera-based nanomaterials and evaluation of the mechanistic basis of their antimicrobial action. Accordingly, Cocos nucifera extract was used for the reduction of silver nitrate solution to afford silver nanoparticles. These entities were further incorporated onto sulfuric-acid-based activated carbons to generate the nanocomposites. The antimicrobial activity of the as-prepared nanomaterials was evaluated using the broth microdilution method, while the antioxidant activity was assessed through standard methods. The cytotoxicity of potent nanomaterials was assessed on Vero cells by the spectrophotometric method. As a result, nanoparticles were successfully synthesized, as evidenced by the ultraviolet–visible spectroscopy analysis that revealed an intense absorption spectrum at 433 nm. Fourier Transform Infrared Spectroscopy presented the functional group moieties involved as a capping and reducing agent in the synthesis of the nanomaterials. The incubation of nanomaterials with selected bacterial and fungal strains has led to significant inhibitory effects of these pathogens with minimum inhibitory concentrations ranging from 7.813 to 250 μg/mL. In antioxidant assays, the nanocomposites presented scavenging activities comparable to those of ascorbic acid. Cytotoxicity experiment revealed no toxic effects on Vero cells (range of selectivity indices: from >4 to >128). These results provide evidence of the implication of Cocos nucifera-based nanomaterials in targeting bacterial or fungal systems that mediate free-radical damage or by inhibiting the oxidative damage caused by selected bacteria and fungi, the most susceptible being Escherichia coli and Candida albicans, respectively.
Zuriatou Yajeh Tanka, Naphtali Odogu Ankoro, Vincent Ngouana, Franklin Loïc Tchinda Taghu, Abongta Lum Mforbesi, Branly-Natalien Nguena-Dongue et 4 autre(s)
Preprints.org
Caused by pathogenic microorganisms, such as bacteria, parasites, fungi, among others, infectious diseases can spread directly or from one individual to another. According to the World Health Organization, these diseases are known to cause high mortality rates, severe burdens of disability and serious worldwide aftermaths. The inappropriate use of antibiotics in humans are the main origins of the development of drug-resistant pathogens, which reduce the efficacy of these therapies, thus accentuating the need to search for effective antimicrobials. Medicinal plants have served as starting material for the preparation of a number of antimicrobial agents. To this end, the present study highlights the green synthesis of Cocos nucifera-based nanomaterials and evaluation of the mechanistic basis of their antimicrobial action. Accordingly, Cocos nucifera extract was used to reduce different concentrations (5, 10 and 20 mM) of silver nitrate solution to afford silver nanoparticles (AgNPs). These entities were further incorporated onto activated carbons (obtained by chemical activation using sulphuric acid as activation agent) to generate the nanocomposites. The antimicrobial activity of the as-prepared nanomaterials was evaluated using the broth microdilution method, while, the antioxidant activity was assessed through standard methods, such as 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2,2&#039;-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. Cytotoxicity of potent nanomaterials was assessed on Vero cells by spectrophotometric method. As a result, nanoparticles were successfully synthesized as evidenced by the color change of the solution from transparent to dark brown. Further characterization was carried out by UV-visible spectroscopy that showed an intense absorption spectrum at 433 nm. Fourier Transform Infrared Spectroscopy (FTIR) revealed the functional group moieties involved as a capping and reducing agent in the synthesis of AgNPs. The incubation of nanomaterials with selected bacterial and fungal strains led to significant inhibitory effects of these pathogens with minimum inhibitory concentrations ranging from 7.813 to 250 μg/ml. In antioxidant assays, the nanocomposites presented scavenging activities comparable to that of ascorbic acid. Cytotoxicity experiment revealed no toxic effects on the human mammalian cells Vero (range of selectivity indices: from &amp;gt;4 to &amp;gt;128). These results provide evidence of the implication of Cocos nucifera-based nanomaterials in targeting bacterial or fungal systems that mediate free-radical damage or by inhibiting the oxidative damage caused by selected bacteria and fungi, the most susceptible being Escherichia coli and Candida albicans, respectively.
François Nguimatsia, Evariste Josué Momo, Paul Keilah Lunga, Virginia Lum Tamanji, Boniface Pone Kamdem, Pierre Michel Jazet Dongmo
Preprints.org
High rates of resistance to antibiotics are associated with healthcare-related infections, thus appealing for the urgent need for effective antimicrobials against these maladies. The present study aims to determine the chemical composition of essential oil (EO) from Clausena anisata leaves, and evaluate their antibacterial activity against selected nosocomial bacteria. Fresh leaves of Clausena anisata were subjected to a steam distillation using a Clevenger apparatus to afford the essential oil. The phytochemical composition of this oil was analyzed using gas chromatography-mass spectrometry (GC-MS). The essential oil was further tested against selected nosocomial bacteria, including Staphylococcus and Klebsiella species, among others, using a microdilution method. As a result, 0.77% of essential oil was extracted from fresh leaves of Clausena anisata. The GC-MS analysis revealed that the as-prepared essential oil contain E-anethole (70.77%), methyl isoeugenol (13.85%), estragole (4.10%), &gamma;-terpinene (3.33%), myrcene (2.82%) and sabinene (0.77%), with E-anethole being the major constituent. Meanwhile, twenty two compounds were identified in the EO of Clausena anisata leaves through gas chromatography. Upon antibacterial test against selected nosocomial pathogens, the E-anethole-rich essential oil exhibited minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranging from 3.91 to 125 &micro;g/mL and 7.81 to 125 &micro;g/mL, respectively, indicative of a bactericidal orientation of the plant&rsquo;s essential oil (MIC/MBC ratio: 4). This novel contribution highlights the scientific validation of the use of Clausena anisata leaves in the traditional treatment of various infectious diseases. However, toxicity and pharmacokinetic studies, mechanistic basis of the antibacterial action, and in vivo antibacterial experiments of the E-anethole-rich essential oil of Clausena anisata should be investigated to successfully use this plant in the treatment of infectious diseases.
François Nguimatsia, Evariste Josué Momo, Paul Keilah Lunga, Virginia Lum Tamanji, Boniface Pone Kamdem, Pierre Michel Jazet Dongmo
Drugs and Drug Candidates
High rates of resistance to antibiotics are associated with healthcare-related infections, thus demonstrating the urgent need for effective antimicrobials against these maladies. The present study aims to determine the chemical composition of essential oil (EO) from Clausena anisata leaves and evaluate their antibacterial activity against selected nosocomial bacteria. To this end, one kilogram (1 kg) of fresh leaves of C. anisata was washed and boiled with 500 mL of distilled water for 2−4 h using a Clevenger apparatus. The oil was then collected in an Erlenmeyer, dried using anhydrous sodium sulfate, bottled in a tinted glass bottle and refrigerated at 4 °C before analysis. Next, the as-prepared oil was analyzed using gas chromatography-mass spectrometry (GC-MS). The essential oil was further tested against a panel of selected nosocomial bacteria, including Staphylococcus and Klebsiella species, among others, by microdilution using a resazurin assay to determine the minimum inhibitory and minimum bactericidal concentrations (MICs and MBCs, respectively). As a result, 0.77% of EO was extracted from fresh leaves of C. anisata. The GC-MS analysis revealed that the as-prepared essential oil contained E-anethole (70.77%), methyl isoeugenol (13.85%), estragole (4.10%), γ-terpinene (3.33%), myrcene (2.82%) and sabinene (0.77%), with E-anethole being the major constituent. Twenty-two compounds were identified in the EO of C. anisata leaves through gas chromatography. Upon antibacterial testing against selected nosocomial pathogens, the E-anethole-rich essential oil exhibited MIC and MBC values ranging from 3.91 to 125 µg/mL and 7.81 to 125 µg/mL, respectively, indicative of a bactericidal orientation of the plant’s essential oil (MIC/MBC ratio < 4). This novel contribution highlights the scientific validation of the use of C. anisata leaves in the traditional treatment of various infectious diseases. However, toxicity and pharmacokinetic studies, mechanistic bases of the antibacterial action, and in vivo antibacterial experiments of the E-anethole-rich EO of C. anisata should be investigated to successfully use this plant in the treatment of infectious diseases.
Patrick Kevin Moto Feune, Paulin Teko Keumedjio, Sara Nathalie Edjenguèlè Béboy, Yannick Sani Jignoua, Fabiola Jenny Massah, Sylvestre Tsila Saidou et 3 autre(s)
Journal of Ethnopharmacology
Franklin Loic Tchinda Taghu, Boniface Pone Kamdem, Vincent Ngouana, Zuriatou Yajep Tanka, Victorine Lorette Yimgang, Julius Nsami Ndi et 2 autre(s)
Preprints.org
In this study, we report the antibacterial mechanisms of action of uniform silver nanoparticles (AgNPs) and decorated activated carbon nanocomposite (CAC-AgNPs) obtained using a green synthesis approach. The nanomaterials were characterized by ultraviolet-visible (UV-vis) absorption spectra and Fourier transform infrared (FTIR) spectra. The antibacterial activity of the as-prepared nanomaterials was evaluated against an array of bacterial strains by microdilution method, whereas their cytotoxicity profile was evaluated on Vero cells (human mammalian cells). The antibacterial mechanistic studies of active nanomaterials were carried out through bacterial growth kinetics, nucleic acid leakage test, and catalase inhibition assay. A silver nanocomposite was successfully fabricated from Croton macrostachyus-based activated carbon. The as-prepared nanomaterials exhibited antibacterial activity against an array of bacterial strains (minimum inhibitory concentration (MIC) range: 62.5 to 500 &micro;g/mL), the most susceptible being Escherichia coli and Staphylococcus aureus. Cytotoxicity studies of the nanomaterials on Vero cells revealed that the nanocomposite (median cytotoxic concentration (CC50): 213.6 &micro;g/mL) was less toxic than the nanoparticles (CC50 value: 164.75 &micro;g/mL) counterpart. Antibacterial mechanistic studies unveiled that the nanomaterials induced (i) bacteriostatic activity vis-&agrave;-vis E. coli and S. aureus and (ii) inhibition of catalase in these bacteria. This novel contribution on the antibacterial mechanisms of action of silver nanocomposite from C. macrostachyus-based activated carbon might contribute to the understanding of antibacterial action of these biomaterials. Nevertheless, more chemistry and in vivo experiments, as well as in depth antibacterial mechanistic studies are warranted for the successful utilization of these antibacterial biomaterials.
Branly-Natalien Nguena-Dongue, Boniface Pone Kamdem, Paul Keilah Lunga, Fabrice Fekam Boyom
Preprints.org
Plants belonging to the genus Irvingia are widespread across the African and Southeast Asian regions of the world. Irvingia gabonensis, Irvingia malayana, and Irvingia grandifolia are among the commonly used species in ethnomedicine, especially in Africa. Fever, scabies, toothache, inflammation, and liver and gastrointestinal disorders are among the pathological conditions that are reverted by Irvingia plants upon traditional preparations. Modern pharmacological investigations have substantiated the ethnomedicinal uses of Irvingia spp. Reports on the phytochemical analysis of Irvingia plants have revealed the presence of a number of secondary metabolites, such as flavonoids, phenolic compounds, tannins, saponins and alkaloids. Based on the foregoing, the present study provides a comprehensive evaluation of reports on the ethnomedicinal use, phytochemistry, pharmacology, and toxicity of plants from the genus Irvingia. Relevant information on Irvingia plants was mostly obtained from major scientific databases from their inception until July 2023. As a result, more than forty compounds have been identified in Irvingia spp. proving the abundance of secondary metabolites in these plants. Reports have pointed out modern pharmacological activities, such as antiprotozoal, antimicrobial, antioxidant, antidiabetic, anti-inflammatory, and hepatoprotective activities. The present study provides more insights for the successful utilization of Irvingia plants and may guide further research on their therapeutic potential in the treatment of various diseases.
Branly-Natalien Nguena-Dongue, Boniface Pone Kamdem, Paul Keilah Lunga, Fabrice Fekam Boyom
Drugs and Drug Candidates
Plants belonging to the genus Irvingia are widespread across the African and Southeast Asian regions of the world. Irvingia gabonensis, Irvingia malayana, and Irvingia grandifolia are among the commonly used species in ethnomedicine, especially in Africa. Fever, scabies, toothache, inflammation, and liver and gastrointestinal disorders are among the pathological conditions that are reverted by Irvingia plants upon traditional preparations. Modern pharmacological investigations have substantiated the ethnomedicinal uses of Irvingia spp. Reports on the phytochemical analysis of Irvingia plants have revealed the presence of a number of secondary metabolites such as flavonoids, phenolic compounds, tannins, saponins, and alkaloids. Based on the foregoing, the present study provides a comprehensive evaluation of reports on the ethnomedicinal use, phytochemistry, pharmacology, and toxicity of plants from the genus Irvingia. Relevant information on Irvingia plants was mostly obtained from major scientific databases from their inception until July 2023. As a result, more than forty compounds have been identified in Irvingia spp., proving the abundance of secondary metabolites in these plants. Reports have pointed out modern pharmacological activities such as antiprotozoal, antimicrobial, antioxidant, antidiabetic, anti-inflammatory, and hepatoprotective activities. The present study provides more insights for the successful utilization of Irvingia plants and may guide further research on their therapeutic potential in the treatment of various diseases.
Brice Rostan Pinlap, Boniface Pone Kamdem, Eutrophe Le Doux Kamto, Vincent Ngouana, Yanick Kevin Melogmo Dongmo, Paul Keilah Lunga et 1 autre(s)
South African Journal of Botany
Shigellosis is a disease condition caused by various species of the genus Shigella . Drug resistant Shigella has been identified as a pathogen for which there is a priority to develop antimicrobials. Cardiospermum grandiflorum and Blighia welwitschii are plants that have been used in ethnomedicine to treat diarrheal conditions. Scientific validation of the antibacterial efficacy of these plants is proven valuable. The present work aimed to investigate the antibacterial activity of extracts from C. grandiflorum and B. welwitschii against Shigella species. The antibacterial activity was evaluated against four species of Shigella using the broth microdilution method, whereas antioxidant activity was performed via colorimetric methods. Cytotoxicity test was carried out using Vero cells. Moreover, the phytochemical analysis of the active extracts was estimated using standard methods. Upon in vitro studies, extracts from C. grandiflorum and B. welwitschii inhibited the growth of three strains of Shigella species viz. Shigella flexneri, Shigella boydii and Shigella sonnei , with minimum inhibitory concentrations (MICs) less than 1000 µg/mL. Remarkably, cytotoxicity studies of the most promising extracts ( B. welwitschii extracts) on Vero cells showed no toxicity. Concentration and time dependent antimicrobial test revealed the bactericidal orientation of B. welwitschii extracts at 4MIC. The phytochemical analysis showed that B. welwitschii extracts are rich in phenolics, flavonoids , tannins, etc. Overall, extracts from C. grandiflorum and B. welwitschii exhibited moderate to high and selective anti- Shigella activity. The present work demonstrated that B. welwitschii extracts are selective bactericidal and antioxidant extracts that can be further exploited as a source of potential anti- Shigella compounds. Nonetheless, isolation of antishigellosis compounds from B. welwitschii extracts, and their mechanistic studies are warranted.
Branly-Natalien Nguena-Dongue, Joseph Tchamgoue, Yvan Anderson Ngandjui Tchangoue, Paul Keilah Lunga, Rufin Marie Kouipou Toghueo, Menkem Elisabeth Zeuko`o et 4 autre(s)
PLoS ONE
Staphylococcus aureus, the causative agent of many infectious diseases has developed resistance to many antibiotics, even chloramphenicol which was the essential antibiotic recommended for the treatment of bacterial infection. Thus, other alternatives to fight against S. aureus infections are necessary; and combinatory therapy of antibiotics with natural compounds is one of the approaches. This study evaluated the activity of the combination of mallotojaponin B and chloramphenicol against Methicillin-resistant Staphylococcus aureus (MRSA). Antibacterial activities were evaluated by broth microdilution and the checkerboard methods. Modes of action as time-kill kinetic, Nucleotide leakage, inhibition and eradication of biofilm, and loss of salt tolerance were evaluated. Cytotoxicity was evaluated on Vero and Raw cell lines. Mallotojaponin B showed good activity against MRSA with a MIC value of 12.5 μg/mL. MRSA showed high resistance to chloramphenicol (MIC = 250 μg/mL). The combination produced a synergistic effect with a mean FICI of 0.393. This combination was bactericidal, inducing nucleotide leakage, inhibiting biofilm formation, and eradicating biofilm formed by MRSA. The synergic combination was non-cytotoxic to Vero and Raw cell lines. Thus, the combination of mallotojaponin B and chloramphenicol could be a potential alternative to design a new drug against MRSA infections.
Paul Keilah Lunga, Jean‐De‐Dieu Tamokou, Siméon P.C. Fodouop, Jules‐Roger Kuiate, Joseph Tchoumboué, Donatien Gatsing
SpringerPlus
Paullinia pinnata Linn (Sapindaceae) is a medicinal plant, locally used in the West Region of Cameroon for the treatment of typhoid fever. This work was designed to evaluate the antityphoid and antioxidant activities of the extracts and compounds of P. pinnata. The methanol extracts of the leaves and stems were tested for antityphoid and antioxidant activities. Compounds were isolated, and their structures elucidated by analysis of spectroscopic data in conjuction with literature data and tested for the same activities. The leaf extract was also tested in vivo for its antityphoid potential in a Salmonella typhimurium-induced typhoid fever model in Wistar rats. Seven known compounds: methylinositol (1), β-sitosterol (2), friedelin (3), 3β-(β-D-Glucopyranosyloxy)stigmast-5-ene (4), (3β)-3-O-(2'-Acetamido-2'-deoxy-β-D-glucopyranosyl) oleanolic acid (5), (3β,16α-hydroxy)-3-O-(2'-Acetamido-2'-deoxy-β-D-glucopyranosyl) echinocystic acid (6) and (3β,)-3-O-[β-D-glucopyranosyl-(1″-3')-2'-acetamido-2'-deoxy-β-D-galactopyranosyl]oleanolic acid (7) were isolated. Compounds 5 and 1 showed the highest antibacterial (MIC = 0.781-1.562 μg/ml) and DPPH radical scavenging (RSa50 = 19.27 ± 4.43 μg/ml) activities respectively. The maximum extract dose (446.00 mg/kg bw) had comparable activity with ciprofloxacin (7.14 mg/kg bw) and oxytetracycline (5 mg/kg bw). The extract induced significant dose-dependent increase of WBCs and lymphocytes. These results support the ethnomedicinal use of P. pinnata and its isolated Compounds could be useful in the standardization of antityphoid phytomedicine from it.
Xing‐Wei Yang, Xiao‐Dong Luo, Paul Keilah Lunga, Yun‐Li Zhao, Xu‐Jie Qin, Yingying Chen et 3 autre(s)
Tetrahedron
Jean‐De‐Dieu Tamokou, Deke James Simo Mpetga, Paul Keilah Lunga, Mathieu Téné, Pierre Tane, Jules Roger Kuiaté
BMC Complementary and Alternative Medicine
BACKGROUND: Albizia adianthifolia is used traditionally in Cameroon to treat several ailments, including infectious and associated diseases. This work was therefore designed to investigate the antioxidant and antimicrobial activities of ethyl acetate extract, fractions and compounds isolated from the stem bark of this plant. METHODS: The plant extract was prepared by maceration in ethyl acetate. Its fractionation was done by column chromatography and the structures of isolated compounds were elucidated using spectroscopic data in conjunction with literature data. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays were used to detect the antioxidant activity. Broth micro-dilution method was used for antimicrobial test. Total phenol content was determined spectrophotometrically in the extracts by using Folin-Ciocalteu method. RESULTS: The fractionation of the extract afforded two known compounds: lupeol (1) and aurantiamide acetate (2) together with two mixtures of fatty acids: oleic acid and n-hexadecanoic acid (B₁); n-hexadecanoic acid, octadecanoic acid and docosanoic acid (B₂). Aurantiamide acetate was the most active compound. The total phenol concentration expressed as gallic acid equivalents (GAE) was found to vary from 1.50 to 13.49 μg/ml in the extracts. The antioxidant activities were well correlated with the total phenol content (R² = 0.946 for the TEAC method and R² = 0.980 for the DPPH free-radical scavenging assay). CONCLUSIONS: Our results clearly reveal that the ethyl acetate extract from the stem bark of A. adianthifolia possesses antioxidant and antimicrobial principles. The antioxidant activity of this extract as well as that of compound 2 are being reported herein for the first time. These results provide promising baseline information for the potential use of this plant as well as compound 2 in the treatment of oxidative damage and infections associated with the studied microorganisms.
Gerald Ngo Teke, Paul Keilah Lunga, Hippolyte K. Wabo, Jules‐Roger Kuiate, Jean Paul Dzoyem
Pharmacologia
Gerald Ngo Teke, Paul Keilah Lunga, Hippolyte K. Wabo, Jules‐Roger Kuiate, Gérard Vilarem, Géraldine Giacinti et 2 autre(s)
BMC Complementary and Alternative Medicine
BACKGROUND: The aim of this study was to evaluate the antimicrobial and antioxidant activities of the methanol extract, fractions and isolated compounds from Entada abyssinica stem bark, plant used traditionally against gastrointestinal infections. METHODS: The methanol extract of E. abyssinica stem bark was pre-dissolved in a mixture of methanol and water, and then partitioned between n-hexane, ethyl acetate and n-butanol. The ethyl acetate portion was fractionated by column chromatography and the structures of isolated compounds elucidated by analysis of spectroscopic data and comparison with literature data. Antimicrobial activity was assayed by broth microdilution techniques on bacteria and yeasts. The antioxidant activity was determined by DPPH radical scavenging method. RESULTS: Four known compounds [(5S,6R,8aR)-5-(carboxymethyl)-3,4,4a,5,6,7,8,8a-octahydro-5,6,8a-trimethylnaphthalenecarboxylic acid (1), methyl 3,4,5-trihydroxybenzoate (2), benzene-1,2,3-triol (3) and 2,3-dihydroxypropyltriacontanoate (4)] were isolated. Compared to the methanol extract, fractionation increased the antibacterial activities of the n-hexane and ethyl acetate fractions, while the antifungal activities increased in ethyl acetate, n-butanol and aqueous residue fractions. The isolated compounds were generally more active on bacteria (9.7 to 156.2 μg/ml) than yeasts (78.1 to 312.5 μg/ml). Apart from compound 1, the three others displayed DPPH· scavenging activity (RSa), with RSa50 values of 1.45 and 1.60 μg/ml. CONCLUSION: The results obtained from this study support the ethnomedicinal use of E. abyssinica in the treatment of gastrointestinal infections and the isolated compounds could be useful in the standardisation of antimicrobial phytomedicine from this plant.
Pythagore Soubgwi Fogue, Paul Keilah Lunga, Emmanuel Sopbué Fondjo, Jean‐De‐Dieu Tamokou, Thaddée Boudjeko, Joseph Tsemeugne et 2 autre(s)
Mycoses
The increasing recognition and importance of fungal infections, the difficulties encountered in their treatment and the increase in resistance to antifungal agents have stimulated the search for therapeutic alternatives. The objective of this study was to evaluate the antifungal activities of three substituted 2-aminothiophenes (1, 2 and 3) against some fungal species. The synthesis of substituted 2-aminothiophenes was carried out through the most versatile synthetic method developed by Gewald et al. The antifungal activity was performed against yeast, dermatophytes and Aspergillus species using the broth microdilution method. The effect of these aminothiophenes was examined on the protein content and profile. Compound 2 was the most active (MIC varying from 2.00 to 128 μg ml(-1) ). All the three substituted 2-aminothiophenes had a relatively important dose-dependent effect on Microsporum gypseum protein profile and content. These compounds affected the structure and dye fixation of macroconidia of this fungus. The overall results indicate that the tested substituted 2-aminothiophenes can be used as precursors for new antifungal drugs development.
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