Abstract: OBJECTIVE:To study the hepatotoxicity of aqueous extract of Polygoni Multiflori Radix with or without incubation with the rat liver microsome. METHODS:Aqueous extract of Polygoni Multiflori Radix was incubated with or without rat liver microsome in vitro and then dried by freeze drying. Liver L02 and HepG2 cells were incubated with different concentrations of the freeze-dried extract(1.5,3,6,12 mg/mL) for 24 h,48 h. Cell vitability was assayed by MTT method. In addition,contents of three main components (trans-2,3,5,4'-tetrahydroxystibene-2-O-β-D-glucopyranoside,emodin-8-O-β-glucopy-ranoside,emodin) from aqueous extract of Polygoni Multiflori Radix after incubation were quantitated by HPLC analysis. RESULTS:The aqueous extract without incubation with rat liver microsome showed more toxicity at the concentration of 12 mg/mL than that with incubation (P < 0.01). Contents of the three main components of aqueous extract incubated with rat liver microsome were lower than those without rat liver microsome. CONCLUSION:Hepatotoxicity of aqueous extract of Polygoni Multiflori Radix was decreased after their metabolism by rat liver microsome. The relationship between reduced contents of the main components of the aqueous extract and the reduction of hepatotoxicity need further study for clarification.

Key words: Polygoni Multiflori Radix, aqueous extract, liver microsome, hepatotoxicity, metabolism