Effect of Larrea tridentata (creosote bush) on cholesterol gallstones and bile secretion in hamsters.

Larrea tridentata (Sesse and Moc. ex DC.) Coville is used for the treatment of gallstones in traditional Mexican medicine. The possible prevention or elimination of gallstones by ethanolic and aqueous extracts of the leaves and twigs of L. tridentata was tested in hamsters fed a rich carbohydrate, fat-free diet. In addition, the effects of the ethanolic extract and its main metabolite, nordihydroguaiaretic acid, on bile secretion in the perfused liver were tested. In the experiment on prevention of gallstones, the dry ethanolic extract at a level of 0.5% of diet completely inhibited gallstone formation, lowered biliary moles percent cholesterol and increased the proportion of chenodeoxycholic acid of hepatic bile. The dry aqueous extract at a level of 1% of diet did not affect gallstone frequency or biliary parameters. In the experiment on elimination of gallstones, the ethanolic extract significantly reduced gallstone frequency, gallbladder bile cholesterol concentration and moles percent cholesterol. Both the ethanolic extract and nordihydroguaiaretic acid had cholestatic effects in the perfused liver, with an EC50 of 34 and 28 mg dL-1, respectively, when perfused for 10 min. This effect was reversible with concentrations up to 40 mg dL-1. The results indicate that L. tridentata could be useful in the treatment of gallstone disease, however care must be taken due to its hepatotoxicity.