Abstract: BACKGROUND ＆ AIM: To investigate the in vitro effects of ferulic acid, caffeic acid, vanillic acid, aspirin, salicylic acid on DNA damage using the single cell gel electrophoresis(comet assay). MATERIAL AND METHODS: Lymphocytes from healthy volunteers were pre-incubated with these phenolic compounds at various concentrations(50,100, 500 μmol/L) or 500 μmol/L only, the comet assay was performed on challenged or unchallenged cells in parallel, oxidant challenge being induced by 10 min exposure to 40 μmol/L H2O2. RESULTS: Compared to positive control, the tail moments were all reduced after pretreatment of the cells with different phenolic acids at different concentrations and then challenged with H2O2. The protective effects of ferulic acid and vanillic acid were greater, and the upward trend was shown with the increasing dose. Whereas aspirin, salicylic acid, especially caffeic acid at high dose (500 μmol/L) exhibited greater tail moment than low doses(50 μmol/L, 100 μmol/L). The tail moment showed a marked increment compared to control group after treatment of the cells with caffeic acid (500 μmol/L) at 37 ℃ for 30 min (without H2O2 challenged), whereas aspirin(500 μmol/L) and salicylic acid(500 μmol/L) showed no effects. CONCLUSION: Protective effects were showed by all five phenolic compounds at different concentrations. The protective effects of ferulic acid and vanillic acid increased with dose. However caffeic acid showed less protective effects. In fact, incubating lymphocytes with 500 μmol/L caffeic acid alone actually induced DNA damage.Aspirin and salicylic acid also exhibited better antioxidant effects, but whether they have pro-antioxidant effects deserve further investigations.

Key words: ferulic acid, caffeic acid, vanillic acid, aspirin, salicylic acid, single cell gel electrophoresis