Inhibitory effect of ergosterol on bladder carcinogenesis is due to androgen signaling inhibition by brassicasterol, a metabolite of ergosterol.

We previously revealed that Choreito, a traditional Kampo medicine, strongly inhibits bladder carcinogenesis promotion. We have also shown that Polyporus sclerotium, which is one of the crude drugs in Choreito, has the strongest bladder carcinogenesis inhibitory effect and that the ergosterol contained in Polyporus sclerotium is the main active component. In this study, we analyzed the mechanism by which ergosterol inhibits bladder carcinogenesis. Rats were given an N-butyl-N-(4-hydroxybutyl) nitrosamine (BHBN) solution ad libitum, and then a promoter [saccharin sodium (SS), DL-tryptophan, or BHBN] was administered together with ergosterol or its metabolite, brassicasterol. The bladders were removed from rats, and the inhibitory effect on carcinogenesis promotion was evaluated by an agglutination assay with concanavalin A (Con A). Although the oral administration of ergosterol inhibited the promotion of bladder carcinogenesis with SS, the intraperitoneal administration of brassicasterol showed a stronger effect. The effect of brassicasterol on carcinogenesis promotion was observed regardless of the type of promoter. Administration of testosterone to castrated rats increased the number of cell aggregates caused by Con A. In contrast, intraperitoneal administration of brassicasterol to castrated rats treated with testosterone significantly decreased the number of cell aggregates, confirming the inhibition of bladder carcinogenesis promotion. The inhibitory effect of ergosterol on bladder carcinogenesis is due to brassicasterol, a metabolite of ergosterol. The action of brassicasterol via androgen signaling may play a role in the inhibitory effect on bladder carcinogenesis promotion.

Effects of menthol on the pharmacokinetics of triazolam and phenytoin.

We have previously shown that menthol attenuates the anticoagulant effect of warfarin by increasing the expression levels of CYP3A and CYP2C in the liver. This study evaluated the effects of menthol on the pharmacokinetics of the CYP3A substrate triazolam and the CYP2C substrate phenytoin. Menthol was orally administered to mice for 7 d. Twenty-four hours after the administration of menthol, triazolam was orally administered, and the plasma concentration was measured. In addition, the CYP3A metabolic activity for triazolam and the CYP3A expression level in the liver were determined. The effects of menthol on the pharmacokinetics of phenytoin were assessed in the same manner. In the menthol-treated group, the area under the blood concentration-time curve (AUC) of triazolam was lower and its clearance was higher compared with the control group. The CYP3A metabolic activity and CYP3A expression level in the liver were significantly increased in the menthol-treated group compared with the control group. Similarly, the AUC of phenytoin was lower and the hepatic CYP2C expression level was higher in the menthol-treated group. Thus, menthol lowered the plasma concentrations of triazolam and phenytoin when concurrently administered. These effects may be attributed to an increased metabolic activity for these drugs due to the increased expression of CYP3A and CYP2C in the liver.