Antimicrobial constituents from the leaves of Hibiscus tiliaceus L.

Repeated column chromatography resulted in the isolation of two new megastigmane derivatives, methyl-tiliaceates A and B ( 1 and 2 ), along with four known metabolites ( 3 - 6 ) from the leaves of Hibiscus tiliaceus L. The structures of the purified phytochemicals were elucidated by interpreting their NMR, HRESIMS, and CD spectroscopic data, as well as comparison with the previous literature. The compounds isolated were subjected to in vitro antimicrobial assays against a panel of pathogenic microorganisms ( Enterococcus faecalis , Staphylococcus aureus , Bacillus cereus , Escherichia coli , Pseudomonas aeruginosa , Salmonella enterica , and Candida albicans ). Compound 1 showed obvious selective inhibition against the B. cereus strain, whereas 3  -  5 showed weak inhibitory activities against E. faecalis and S. aureus bacterial, and C. albicans fungal strains (with MIC values ranging from 128 to 256  µ g/mL).