Abstract:Enteromorpha prolifera polyphenols (EPs) were extracted and separated, and their antioxidant activity and effect on insulin resistance (IR) were investigated in this paper. The 2,2-diphenyl-1-picrylhydrazyl (DPPH?) radical scavenging assay was used to evaluate the in vitro antioxidant capacities of EPs; the capability of EPs for reducing IR was evaluated in vitro by measuring the glucose consumption of IR-HepG2 cells. Experiments with diet-induced obese (DIO) mice were used to evaluate the in vivo antioxidant activities of EPs and their effects on IR in vivo. The results showed that the fraction EP1 had good DPPH? radical scavenging ability with an IC50 value of 1.08 mg/mL. Compared to the control group, EP1 significantly increased the liver SOD and CAT activities in mice by 25.04% and 36.28%, respectively, and decreased the serum malondialdehyde (MDA) level by 42.92%. EP1 improved IR states of HepG2 cells and DIO mice significantly (p<0.05), reduced the homeostatic model assessment (HOMA)-IR index by 16.8%, and decreased the degree of obesity and reduce the fat percentage in DIO mice significantly（p<0.05）. On the other hand, EP2 was inferior to EP1 in terms of antioxidant activity and IR-improving effect. In summary, EP1 has good in vitro and in vivo antioxidant capacities, and can improve IR state significantly, which may be associated with its antioxidant activity by suppressing levels of reactive oxygen species (ROS).
