Saponins from platycodi radix ameliorate high fat diet-induced obesity in mice

We examined the effects of crude saponins isolated from Platycodi radix on the degree on fat storage induced in mice by feeding a high fat diet for 9 wk. We reported previously that feeding mice a high fat diet for a longer time caused obesity and fatty liver compared with those fed a low fat diet, nonpurified diet. Feeding a high fat diet containing 10 or 30 g/kg crude saponins prevented the body and parametrial adipose tissue weight increases and hepatic steatosis of mice fed the high fat diet alone. Furthermore, crude saponins (375 mg/kg) inhibited the elevations in blood triacylglycerol in rats orally administered a lipid emulsion compared with that of rats given the lipid emulsion alone. Previously, we reported that crude saponins inhibited pancreatic lipase activity in vitro. To identify the active substance(s) of crude saponins, we examined the effects of purified platycodin D, the primary saponin in the crude mixture, on pancreatic lipase activity and on the blood triacylglycerol elevation in rats administered the oral lipid emulsion tolerance test. Platycodin D (0.5 and 1.0 g/L) inhibited pancreatic lipase activity in vitro and at a dose of 244 mg/kg, inhibited the elevation of blood triacylglycerol. Therefore, the antiobesity effect of the crude saponins in mice fed a high fat diet may be due to the inhibition of intestinal absorption of dietary fat by platycodin D.