Research on choleretic effect of menthol, menthone, pluegone, isomenthone, and limonene in DanShu capsule

Danshu capsule (DSC) is a medicinal compound in traditional Chinese medicine (TCM). It is commonly used for the treatment of acute & chronic cholecystitis as well as choleithiasis. To study its choleretic effect, healthy rats were randomly divided into DSC high (DSCH, 900 mg/kg), medium (DSCM, 450 mg/kg), and low (DSCL, 225 mg/kg) group, Xiaoyan Lidan tablet (XYLDT, 750 mg/kg), and saline group. The bile was collected for 1 h after 20-minute stabilization as the base level, and at 1 h, 2 h, 3 h, and 4 h after drug administration, respectively. Bile volume, total cholesterol, and total bile acid were measured at each time point. The results revealed that DSC significantly stimulated bile secretion, decreased total cholesterol level and increased total bile acid level. Therefore, it had choleretic effects. To identify the active components contributing to its choleretic effects, five major constituents which are menthol (39.33 mg/kg), menthone (18.02 mg/kg), isomenthone (8.18 mg/kg), pluegone (3.31 mg/kg), and limonene (4.39 mg/kg) were tested on our rat model. The results showed that menthol and limonene could promote bile secretion when compared to DSC treatment (p > 0.05); Menthol, menthol and limonene could significantly decrease total cholesterol level (p < 0.05 or p < 0.01) as well as increase total bile acid level (p < 0.05 or p < 0.01); Isomenthone, as a isomer of menthone, existed slightly choleretic effects; Pluegone had no obvious role in bile acid efflux. These findings indicated that the choleretic effects of DSC may be attributed mainly to its three major constituents: menthol, menthone and limonene.