Isolation, purification and characterization of betulinic acid derivative from the root bark of Afzelia africana and its antiplasmodial and antimicrobial activities.

BACKGROUND

Afzelia africana is a tropical plant species with numerous documented ethnobotanical and medicinal properties.

AIM/

OBJECTIVE

The study focused on the isolation, purification, characterization and biological activity of betulinic acid from the bark of A. africana.

METHODOLOGY: The series of methods employed include column fractionation and purification, characterization (MS, 1H, 13C, DEPT-135, HSQC, COSY and HMBC), antimicrobial (Micro-broth dilution, and synergistic effects), and antiplasmodial activity (MSF assay).

RESULTS

Repeated column chromatographic fractionation of the methanol (extract eluent: n-hexane-ethyl acetate (75:25)) and TLC profiling afforded a 15 mg white crystal characterized as betulinic acid. The compound reported good antiplasmodial activity against 3D7 strain of P. falciparum (IC50: 12.89 ± 0.52 µg/mL). The compound exhibited varying degrees of bactericidal activities (MBC/MIC ≤ 4) against S. mutans, C. albicans 2, B. subtilis, K. pneumonia and bacteriostatic activities (MBC/MIC ≥ 4) against S. aureus, E. coli, methicillin-resistant S. aureus, P. aeruginosa, S. typhi and C. albicans 1. The compound further reported synergistic effects (FIC ≤ 0.5) against E. coli, K. pneumonia, S. aureus and S. mutans; partial synergism (FIC > 0.5 and < 1) against S. typhi, methicillin-resistant S. aureus, B. subtilis and indifferent effects (FIC > 1 and < 4) against P. aeruginosa when combined with tetracycline. The compound with Ciprofloxacin showed synergistic effect against Klebsiella pneumoniae, Streptococcus mutans, and Salmonella typhi. Additionally, it demonstrated further synergism with tetracycline against Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus. In the antifungal synergistic studies, the combination of the compound with fluconazole and nystatin, ciprofloxacin exhibited partial synergism (FIC > 0.5 and < 1) against one strain of Candida albicans and full synergism (FIC ≤ 0.5) against a second strain of Candida albicans. When combined with fluconazole and nystatin.

CONCLUSION

Betulinic acid has been isolated for the first time from the bark of Afzelia africana. It demonstrated good antiplasmodial activity against P. falciparum, as well as various bactericidal and bacteriostatic effects against multiple microbial strains. Additionally, betulinic acid demonstrated synergistic effects when combined with tetracycline, ciprofloxacin, fluconazole, and nystatin.