Chemical Study on Protective Effect Against Hydroxyl‐induced DNA Damage and Antioxidant Mechanism of Myricitrin

Excessive reactive oxygen species (ROS) can oxidatively damage DNA to cause severe biological consequences. In the study, a natural flavonoid, myricitrin (myricetin‐3‐O‐α‐L‐rhamnopyranoside), was found to have a protective effect against hydroxyl‐induced DNA damage (IC 50 159.86 ± 54.24 μg/mL). To investigate the mechanism, it was determined by various antioxidant assays. The results revealed that myricitrin could effectively scavenge ·OH, ·O 2 − , DPPH· (1,1‐diphenyl‐2‐picrylhydrazyl radical), and ABTS + · (2,2′‐Azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) radicals (IC 50 values were respectively 69.71 ± 5.93, 69.71 ± 5.93, 25.34 ± 2.14, and 1.71 ± 0.09 μg/mL), and bind Cu 2+ (IC 50 27.33 ± 2.36 μg/mL). Based on the mechanistic analysis, it can be concluded that: ( i ) myricitrin can effectively protect against hydroxyl‐induced DNA oxidative damage via ROS scavenging and deoxynucleotide radicals repairing approaches. Both approaches can be attributed to its antioxidant. From a structure‐activity relationship viewpoint, its antioxidant ability can be attributed to the ortho ‐dihydroxyl moiety, and ultimately to the stability of its oxidized form ortho ‐benzoquinone; ( ii ) its ROS scavenging is mediated via metal‐chelating, and direct radical‐scavenging which is through donating hydrogen (H·) and electron ( e ); and ( iii ) its protective effect against DNA oxidative damage may be primarily responsible for the pharmacological effects, and offers promise as a new therapeutic reagent for diseases from DNA oxidative damage.