Abstract: The present aimed to evaluate effects of sclerotia of P.umbellatus FRIES aqueous extract (SPUE) and Polyporus polysaccharide (PPS) on liver metabolic enzyme of Fisher-344 rat induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) combined saccharin.The rat liver enzyme activities of CYP450,glutathione S-transferase (GST),and NAD(P)H:quinone oxidoreductase 1 (NQO1) were determined by ELISA.The relative expressions of liver glutathione S-transferase π (GSTPi) and NQO1 mRNA were measured with RT-PCR.The present report showed the SPUE and PPS decreased the activity of rat liver CYP450 enzyme，the effect had dose-effect relationship; they had no significant effect on the activity of rat liver GST enzyme,and they could increase the activity of rat liver NQO1 enzyme; the high dose SPUE could up-regulate the GSTPi mRNA relative expression in rat liver,they had no effect on the NQO1 mRNA relative expression in rat liver.In conclusion,the inhibition of bladder carcinogenesis by SPUE and PPS associate with the decreasing of rat liver CYP450 enzyme activity and increasing of NQO1 enzyme activity,but the mechanism needs further research.

Key words: sclerotia of Polyporus umbellatus, Polyporus polysaccharide, CYP450, Ⅱ phase enzyme