Tephrosin and obovatachalcone with antibacterial activity from Tephrosia vogelii Hook.f

In the search for new antibacterial agents from plants, two known compounds (rotenoid and chalcone) were isolated from Tephrosia vogelii Hook.f. (seeds), namely tephrosin (1), and obovatachalcone (2). The compounds were isolated using vacuum liquid chromatography and radial chromatography. The structures of isolates were determined by 1D and 2D NMR. Both compounds were evaluated for their antibacterial properties against the four pathogenic bacterial strains Staphylococcus aureus S33 R4, Bacillus subtilis subsp. subtilis str. 168, Escherichia coli TISTR 780, and Salmonella typhi Ty 21a, using the microdilution method to determine MIC and MBC. The results showed that tephrosin (1) had moderate antibacterial activity against E. coli with MIC values of 25 μg/mL and MBC values of 100 μg/mL. However, obovatachalcone (2) showed a weak antibacterial activity.