7,8-dihydroxyflavone displayed antioxidant effect through activating HO-1 expression and inhibiting caspase-3/PARP...

Flavonoids, which contain a benzo-γ-pyrone (C6-C3-C6) skeleton, have been reported to exhibit effective antioxidant ability. This study aimed to compare the antioxidant activities of 7,8-dihydroxyflavone (7,8-DHF) and 7-hydroxyflavone (7-HF) in H₂ O₂ , lipopolysaccharide (LPS), or tert-butyl hydroperoxide (t-BHP)-induced RAW264.7 cells, respectively. The antioxidant capacities of 7,8-DHF and 7-HF were firstly evaluated by 2,2-azinobis-3-ethyl-benzothiazoline-6-sulphonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. Then, reactive oxygen species (ROS), super oxide dismutase (SOD), and malondialdehyde (MDA) productions in H₂ O₂ , LPS, or t-BHP-induced RAW264.7 cells were tested and compared, respectively. Finally, the antioxidant mechanisms of 7-HF and 7,8-DHF were initially investigated by western blot. Our results showed that 7,8-DHF possessed stronger free-radical scavenging capacity than 7-HF. Both 7,8-DHF and 7-HF suppressed MDA production and ROS accumulation, improved the activity of SOD in H₂ O₂ , LPS, or t-BHP-induced RAW264.7 cells, respectively. And 7,8-DHF exerted a better antioxidant effect than 7-HF, especially in t-BHP-induced oxidative stress. Mechanically, 7,8-DHF prevented the activation of poly ADP-ribosepolymerase and caspase-3, meanwhile markedly upregulated the expression of HO-1 protein in t-BHP-induced oxidative stress. These results suggested that 7,8-DHF might serve as a potential pharmaceutical drug against oxidative stress injury.