Platycodi radix affects lipid metabolism in mice with high fat diet-induced obesity

An aqueous extract of Platycodi radix inhibited the hydrolysis of triolein emulsified with phosphatidylcholine by pancreatic lipase in vitro and it re duced the elevation of rat plasma triacylglycerol level 2-4 h after oral ad ministration of a lipid emulsion containing corn oil. These preliminary res ults suggested that the aqueous extract of Platycodi radix may inhibit the intestinal absorption of dietary fat by inhibiting its hydrolysis. Therefor e, we examined the antiobesity activity of the aqueous extract of Platycodi radix by testing whether the extract prevented the obesity induced by feed ing a high fat diet to mice for 8 wk. Body weights at 3-8 wk and the final parametrial adipose tissue weights were significantly lower in mice fed the high fat diet containing 5% aqueous extract of Platycodi radix than in the controls fed the high fat diet. The aqueous extract of Platycodi radix als o significantly reduced hepatic triacylglycerol concentrations that were el evated in mice fed the high fat diet alone. Inulin, which is a major compon ent of Platycodi radix, had no effect on the hydrolysis of triolein emulsif ied with phosphatidylcholine by pancreatic lipase in vitro, and did not pre vent obesity or the fatty liver induced by the high fat diet. On the other hand, the total saponin fraction of the aqueous extract inhibited pancreati c lipase activity in vitro. Therefore, the antiobesity effect of the aqueou s extract of Platycodi radix in mice fed a high fat diet may be due in part to the inhibition of intestinal absorption of dietary fat by the saponins of Platycodi radix.