A new coumaronochromone and a new alkanoyl-dihydrofuranoflavone glycoside from Eriosema robustum (Fabaceae)

A new coumaronochromone, eriocoumaronochromone (1), and a new alkanoyl-dihydrofuranoflavone glycoside, robusflavone C (2), as well as seven known compounds, 6-prenylpinocembrin (3), desmoxyphyllin A (4), prutin (5), genistein (6), vitexin (7), kaempferol (8), and p-hydroxy benzoic acid (9), were obtained after phytochemical re-investigation of the EtOAc-soluble portion from the EtOH extract of the twigs of Eriosema robustum. The structures of the new compounds were elucidated by analyses of their spectroscopic data (1D- and 2D- NMR, and HR-ESIMS) and chemical conversion. 1 and 2 exhibited weak antioxidant activity with IC50 340.3 +/- 0.1 and 524.6 +/- 0.1 mu M in 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical assay, and possessed weak antimicrobial activity with MICS > 150 mu g/mL against Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coil, Candida albicans, and Saccharomyces cerevisiae.