Abstract: Free radical models and a microplate reader were used to explore the scavenging activity of apigenin (API) against hydroxyl and DPPH free radicals. The CuSO4-Phen-VitC-H2O2-DNA chemiluminescence system was employed to determine the inhibitory effect of API on hydroxyl radical-induced DNA damage. Meanwhile, the protective effect and possible mechanisms of API with effective concentration against free radical-induced DNA damage were also explored. The results showed that the scavenging rates of API at the doses of 25, 50, 100μg/mL and 20 0μg/mL within 30 min of reaction against DPPH free radicals were 8.80%, 28.4%, 37.4% and 62.8%, respectively. Similarly, the scavenging rates of API at the doses of 200, 100μg/mL and 50μg/mL on hydroxyl free radicals were 50.2%, 35.4% and 25.4%, respectively. The inhibition rate of API at the concentration range of 25－100μg/mL on chemiluminescence of DNA damage products was 5.6%－16.9% and API also resulted in the delay of DNA damage for 35－50 min. API at low dose could eliminate DPPH and OH free radicals obviously, restrain DNA damage induced by free radicals, and delay DNA damage time. The free radical scavenging activity and anti-DNA damage effect of API were both correlated with its concentration.

Key words: apigenin, free radical, DNA damage, chemiluminescence