Pancreatic lipase inhibitory activity of cassiamin A, a bianthraquinone from Cassia siamea.

In continuation towards the discovery of potential antiobesity lead(s) from natural products, we have screened n-hexane, dichloromethane (DCM), ethyl acetate (EtOAc) and methanol (MeOH) extracts of 33 Indian medicinal plants (200 extracts) for in vitro pancreatic lipase inhibitory activity. Of the screened extracts, the EtOAc extract of Cassia siamea roots showed 74.3 +/- 1.4% enzyme inhibition at 250 microg/mL concentration. Bioassay guided fractionation of the active extract afforded 6 known compounds viz. chrysophanol (1), physcion (2), emodin (3), cassiamin A (4), friedelin (5) and cycloart-25-en-3beta,24-diol (6). These compounds were further evaluated for pancreatic lipase inhibitory activity. Cassiamin A (4), a bianthraquinone, was found to be most active with an IC50 value of 41.8 +/- 1.2 microM and compounds 2 and 5 were found to be moderate enzyme inhibitors. Results indicate the antiobesity potential of C. siamea through pancreatic lipase inhibition.