Publications scientifiques
Aboubakar Mahamat* (Auteur correspondant)
Paul Etoga Mbarga
Ephrem Nkengfack
HAROUN Ali Adannou
Haroun Héloua
American Journal of Applied Chemistry
The present work deals with the isolation, purification and characterization of secondary metabolites of the fruits of Ziziphus mauritiana and the evaluation of their biological activity against Staphylococcus aureus. A plant from the Rhamnaceae family, widely used in the Cameroonian and Tchadian traditional pharmacopoeia for the treatment of various diseases such as food poisoning, pneumonia, urinary tract infections, and skin infections such as wounds and ulcers. Our investigations focused on the methanol/dichloromethane (MeOH/DCM, 1:1) extract of the fruits of Ziziphus mauritiana. Alkaloidal treatment was performed on this extract, and we obtained four (04) fractions: two non-alkaloid fractions, F1 (DCM), F2 (EtOAc), and two alkaloid fractions, F3 (DCM) and F4 (EtOAc). Using usual chromatographic methods (CC, CCM), we isolated from the alkaloidal fraction F3, two compounds 1 and 2, and four compounds 3, 4, 5, 6 from the non-alkaloid fraction F1, the hexane fraction. From these compounds, three (03) were fully characterized using spectroscopic methods 1H and 13C NMR (1 and 2 dimensions) and by comparison of their spectral data with those of the literature. These are: Sanjoinenine 1, betulinic acid 3, and epicatechin 4. The crude extract as well as fraction, and some isolated compounds were evaluated in vitro by the liquid microdilution method described by CLSI, against two strains of Staphylococcus aureus: S. aureus ATCC25923, S. aureus ATCC43300, and a Clinical isolate. The crude extract, fractions F1 and F4, were the most active fractions tested against the strain S. aureus ATCC 25923, with a MIC of 15.6, 62.5, and 15.6 µg/mL, respectively, while the other fractions (F2 and F3) showed moderate activity against the same strain. Fraction F2 is not active. For the S. aureus ATCC 43300, all the fractions have a weak activity, and for the clinical isolate, only ZSA shows a good activity with a MIC of 62.5 µg/mL, and the others show a moderate activity.
