Abstract
Purpose: To isolate new antimicrobial agents from the leaves of Markhamia platycalyx (Baker) Sprague and assess their phytochemical characteristics and antimicrobial activity.
Methods: Different chromatographic and spectroscopic techniques (NMR and ESI-MS) were applied for the identification of antimicrobial compounds. Agar-well diffusion technique was used for determination of antimicrobial activity. Anti-HCV effects were investigated using VITROS Anti-HCV assay.
Results: Eighteen compounds were isolated for the first time from this genus. These were phytol, n-octacosanoic acid (OCTA), tormentic acid and beta-sitosterol-3-O-(6'-O-heptadecanoyl)-beta-D-glucopyranoside. The other compounds were beta-sitosterol, ursolic acid (URSA), oleanolic acids, pomolic acid (POMA), 2-epi-tormentic and beta-sitosterol-3-O-beta-D-glucopyranoside. However, stigmasterol and acteoside, which were seen in previous studies, were also present. Total ethanol extract (TEE) was the most effective against Escherichia coli, with the lowest minimum inhibitory concentration (MIC) of 1.0 mu g/mL. Acteoside, URSA and 2-epi-tormentic acid showed the highest antibacterial effect on Pseudomonas aeruginosa while 2-epi-tormentic acid and acteoside produced the least MIC on Candida glabrata. These effects were superior to those produced by standard antibiotics. However, 2-epitormentic acid and beta-sitosterol-3-O-beta-D-glucopyranoside had no anti-HCV effects.
Conclusion: Due to the good antimicrobial properties of Markhamia platycalyx, it is a potential source of new antimicrobial drugs.