Antigenotoxic effect of Pleurotus cornucopiae extracts on the mutagenesis of Salmonella typhimurium TA 98 elicited by benzo［a］pyrene and oxidative DNA lesions in V 79 hamster lung cells
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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 dosedependent 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 (Ah) ligand of Sudan Ill-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 O-demethylase (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 H_2O_2-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.
- Japanese Journal of Veterinary Research
Japanese Journal of Veterinary Research 52(4), 163-172, 2005-02
The Graduate School of Veterinary Medicine, Hokkaido University