Vitexin, orientin and other flavonoids from Spirodela polyrhiza inhibit adipogenesis in 3T3-L1 cells

To investigate the adipogenesis inhibitory effect on lipid accumulation, 3T3-L1 cells were treated with fractions and isolated flavonoids of Spirodela polyrhiza. An ethanol extract of S. polyrhiza was fractionated into three fractions. The butanol soluble fraction (SPB) exhibited potent antiadipogenesis activity and decreased C/EBPα and PPARγ protein expression level in 3T3-L1 cells without significant cytotoxicity. The flavonoids were isolated from SPB and their chemical structures were identified as chrysoeriol (1), apigenin (2), luteolin (3), vitexin (4), cosmosin (5), orientin (6) and luteolin-7-O-β-d-glucoside (7) by spectroscopic analysis. Studies on the adipogenesis and intracellular triglyceride accumulation inhibitory effect showed that compounds 4 and 6 had the highest activity and decreased C/EBPα and PPARγ protein expression level in 3T3-L1 cells. These results suggest that the flavonoids isolated from SPB, especially compounds 4 and 6, contribute to the inhibitory activity of S. polyrhiza in 3T3-L1 cells.