Isoflavones from the Bark of Ormosia robusta (Fabaceae) baker

Bark of Ormosia robusta (Fabaceae) Baker has been investigated for isolation of secondary metabolites and evaluation of bioactivities. Two prenylated isoflavones, Warangalone (1) and Erysenegalensein M (2), along with two triterpenoids, Betulinic acid (3) and Lupeol (4), have been  isolated from the methanolic extract of the bark by using chromatographic analysis. Structures of these compounds were elucidated by extensive spectroscopic analysis and by comparing the data with the published one. This is the first report of isolation of these compounds from this plant. Subsequently the methanolic extract was fractionated with four organic solvents and all the fractions were studied to evaluate their in vitro bioactivities. Significant variance is observed for polyphenol content as well as free radical scavenging activity (4.17 - 270.42 mg of gallic acid equivalent/gm of extract and DPPH IC50 value: 1.21-6.80 μg/ml) depending on the nature of the solvent partitioned with. The results of the brine shrimp lethality bioassay (LC50 value: 1.49 -33.15 μg/ml) indicate that the plant possesses cytotoxic principal and have considerable toxic potencies.