Abstract: BACKGROUND ＆ AIM： To study isolatel and combined effects of the organic oxidant cumene hydroperoxide (CHP), the inorganic oxidant H2O2 and several antioxidants, on nitric oxide (NO) contents, total carbonyl and malondialdehyde (MDA) of hepatoma cells in different phases of cell cycle. MATERIALS AND METHODS：Hepatoma cells H299(1×106/ml) were synchronized,and then divided into eight groups:the control group(DMSO),CHP (50 μmol/ml), H2O2(50 μmol/ml), CHP＋H2O2 (oxidant componds: H2O2 of 50 μmol/ml plus CHP of 50 μmol/ml), Vit A(10 μmol/ml), Vit E (10 μmol/ml),Na2SeO3 (50 nmol/ml),AO(antioxidant compounds of Vit A＋Vit E＋Na2SeO3 , among them: Vit A and Vit E were 5 μmol/ml each, Na2SeO3 was 25 nmol/ml). They were separately added to cultured cells at G1, S, G2 and M phase of the cell cycle. The cell contents of NO, total carbonyl (T_carbonyl) and MDA were determined. RESULTS： The cell cycle showed better synchronization. The synchronized cells in G1 phase was 86％, in S phase was 78％,and in G2/M phase was 61％. We found that NO of cells stimulated by oxidant componds (CHP and H2O2) at G1 phase were significantly increased (P<0.05) while they were inhibited by Vit A (P<0.05). The oxidant componds (CHP and H2O2) had stimulatory function, and Vit A、Vit E、Na2SeO3 had obvious inhibitory effects on T_carbony contents throughout the whole cell cycle (P<0.05). The levels of MDA in synchronized cultured cells were elevated by H2O2 at G2/M phase, and were decreased by antioxidant compounds Vit A＋Vit E＋Na2SeO3 at G2 phase (P<0.05). CONCLUSION： After synchronization, the actions of organic oxidant, inorganic oxidant, and the tested antioxidants varied according to the different phases in the tumor cell cycles. Hepatoma cells in G1 phase were sensitive to oxidant compounds (CHP and H2O2) and Vit A on the oxidative injury NO level. The cellular oxidative injury marker MDA contents in hepatoma cells in G2 phase were significantly altered by H2O2 and antioxidant compounds (Vit A＋Vit E＋Na2SeO3).

Key words: free radicals, antioxidants, cell circle, modulation