ANTIMICROBIAL MEGASTIGMANES AND NUCLEOSIDES ISOLATED FROM THE LEAVES OF THESPESIA POPULNEA

A phytochemical investigation of the ethanolic extract of Thespesia populnea (L.) Sol. ex Correa leaves led to the isolation of six compounds (1‒6), using various chromatographic techniques. Their structures were elucidated as dihydrophaseic acid (1), icariside B1 (2), icariside B2 (3), 3β,5α,6β,9β-tetrahydroxymegastigman-7-ene (4), L-thymidine (5), and L-uridine (6) based on detailed analyses of 1D and 2D NMR, as well as mass spectrometric data, and by comparison with previously reported structures. The antimicrobial assays demonstrated that compound 1 selectively inhibited Candida albicans fungus with an MIC value of 64 μg/mL, while 4 exhibited weak inhibition against Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus bacterial strains with an MIC value of 128 µg/mL. This is the first time megastigmane and nucleoside constituents from T. populnea have been reported.