Bioassay-guided isolation of anti-adipogenic compounds from defatted pepper (Capsicum annuum L.) seeds

The extracts of pepper (Capsicum annuum L.) seeds are known to inhibit differentiation and adipogenesis of 3T3-L1 preadipocytes. In this study, bioassay-guided fractionation of a crude ethanolic extract from defatted pepper seeds led to the isolation of two anti-adipogenic furostanol saponins, capsicoside A and capsicoside G. The anti-adipogenic activity of these compounds was evaluated by measuring their inhibitory effect on lipid accumulation in 3T3-L1 adipocytes. The chemical structures of the pure compounds were elucidated using spectroscopic methods (1H, 13C NMR, and ESI-MS) and compared with the available data in the literature. The results of activity screening showed that capsicosides A and G (1-20 µg/mL) reduced intracellular lipid accumulation in 3T3-L1 adipocytes in a dose-dependent manner without causing cytotoxicity. The inhibitory effect of capsicoside G at 20 µg/mL on the lipid accumulation during 3T3-L1 adipocyte differentiation was significantly greater than that of capsicoside A at the same concentration. These results suggest that capsicoside G isolated from pepper seeds may prevent obesity.