In vitro inhibitory effect of triterpenoidal saponins from Platycodi Radix on pancreatic lipase.

In the process of investigating anti-obesity effect of Platycodi Radix, we found that aqueous extract of Platycodi Radix might inhibit intestinal absorption of dietary fat by inhibiting pancreatic lipase (PL) activity. In order to clarify the anti-obesity mechanism of Platycodi Radix, activity-guided isolation was performed to find active components. The total saponin fraction of Platycodi Radix appeared to have a potent inhibitory activity against the hydrolysis of triolein emulsified with phosphatidycholine by pancreatic lipase in vitro. Based on these results, further purification of active components yielded 10 known triterpenoidal saponins, among these compounds, platycodin A, C, D, and deapioplatycodin D exhibited significant inhibitory effects on PL at the concentration of 500 microg/mL with 3.3, 5.2, 34.8, and 11.67% pancreatic lipase activity vs control, respectively. Platycodin D was found to inhibit the PL activity in a dose-dependent manner. Therefore, the anti-obesity effect of Platycodi Radix might be due to the inhibition of pancreatic lipase by its saponins.