Abstract: BACKGROUND ＆ AIM： To investigate the toxic effects of aristolochic acid I,aristolochic acid II and aristolochic acid Ia on renal proximal tubular epithelial cell (cell line HK-2) in vitro. MATERIAL AND METHODS: The morphological changes of HK-2 cell were examined with contrast microscopy and the growth inhibition of HK-2 after treatment with the three aristolochia compounds was studied by[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT]assay. The drug treatment group, negative control group and blank control group were set up. The expression of α-smooth muscle actin was defected by immunohistochemistry and cell cycle and apoptosis rate were defermined by flow cytometry. RESULTS: Under the light microscope, HK-2 cells became contracted and rounded in AAI and AAIa groups.The expression of α-smooth muscle actin increased in the AAI,AAII and AAIa groups compared with control; the three compounds all induced the inhibition the growth of HK-2 cells in concentration-and time-dependent manner.The median inhibitory concentration(IC50) revealed that inhibition intensities were AAI>AAIa>AAII. All these compounds could affect cell cycle and even induce cell apoptosis. CONCLUSION: AAI,AAII and AAIa were cytotoxic to various extents which might have resulted from different mechanisms.

Key words: aristolochic acid, HK-2 cell, cytotoxicity