Phytochemical and antimicrobial studies of Pachypodium lamerei

Five compounds were reported for the first time in the tribe Malouetieae from the leaves and stems of Pachypodium lamerei viz., fatty acid methyl ester (stearic acid methyl ester 1), a mixture of two steroidal aglycones (β-sitosterol 2 and stigmasterol 3), a pentacyclic triterpene (ursolic acid 4) and a steroidal glucoside (β-sitosterol-3-O-β-D-glucopyranoside 5). The structure elucidation was based on comparison of their physical, chemical, chromatographic properties, spectral data with literature as well as direct comparison with authentic compounds. The petroleum ether fraction and the total ethanolic extract of (leaves and stems) exhibited minimum inhibitory concentrations (MICs) against Pseudomonas aeruginosa (1.06 and 2.52 μg/ml), respectively. These results are comparable to that obtained by amikacin (MIC, 2.38 μg/ml). Moreover, the petroleum ether fraction displayed the lowest MIC (16.45 μg/ml) against Candida albicans. This result is greatly promising since the standard drug (ketoconazole) exhibited MIC (185.87 μg/ml). This is the first time to estimate both antibacterial and antifungal activities of any of Pachypodium species. Key words: Pachypodium lamerei, Apocynaceae, phytochemical, antimicrobial, antibacterial, antifungal.