Pleurotus cornucopiae (PC) mushrooms are found in the field and commonly known in Japan as Tamogidake mushrooms. The present study investigated the protective effects of an aqueous extract of PC on carbon tetrachloride (CCl4)-induced hepatotoxicity and the possible mechanism involved in this protection including cytochrome P450 (CYP) 2E1. Wistar rats were pretreated with aqueous extracts of PC (0, 100, 200, and 400 mg/kg) orally for 8 days prior to the intraperitoneal administration of a single dose of CCl4 (0.5 ml/kg) or corn oil. Pretreatment with PC mushroom extract significantly prevented the increased serum enzyme activities of alanine and aspartate aminotransferases in a dose-dependent manner, and suppressed the expression of CYP2E1. PC mushroom extract also protected hepatocytes from the damage effects of CCl4 as remarked by histological and electromicroscopical findings. It was concluded that repeated daily doses of aqueous extracts of PC mushroom reduced the toxic effects exerted by CCl4 on the liver.

Pleurotus cornucopiae (PC) mushroom with a brilliant yellow pileus is found in the field and known in Japan as Tamogi dake mushroom. The purpose of this paper is to investigate the mechanism of the antimutagenic effect of PC mushroom using both the Ames test and Comet assay. We have found a strong inhibitory effect of both aqueous and organic PC extracts on the mutagenicity elicited by benzo[a]pyrene (B[a]P). This inhibition was dose- dependent in reaction mixtures containing cytosolic and microsomal fractions (S-9) from untreated rat liver as well as in those containing S-9 from aryl hydrocarbon receptor (Au) ligand of Sudan III-treated rats. Sudan III was a potent inducer of cytochrome P450 1A (CYP1A) activity. We treated rats with Sudan III to enhance the metabolic activation of B[a]P by the S-9 fraction. To explain whether this antimutagenicity was due to the inhibition of CYP1A activity that metabolically activates B[a]P, we tested the effects of the extracts on activities of CYP1A1 and CYP1A2, represented by ethoxyresorufin Odeethylase (EROD) and methoxyresorufin Odemethylase (MROD), respectively. Both aqueous and organic extracts inhibited EROD activity at all dose levels, while the inhibitory effect was only observed at high doses with regard to MROD activity. Furthermore, pre-treatment of Chinese hamster V79cells with PC extracts significantly reduced H2O2 - induced-DNA damage, indicating that PC extracts provide a protective effect against oxidative DNA damage. These results indicate that whole-mushroom extracts contain compounds that may inhibit the metabolic activation of B[a]P by CYP1A1 as well as prevent oxidative DNA damage.