Antioxidative and Hypoglycemic Effects of Silk Fibroin/SericinMixtures in High Fat-Fed Mice

The effect of dietary feeding of silk fibroin/sericinmixtureson the antioxidative status and glucose metabolism in high fat-fed mice was investigated. The mice weregiven experimental diets for 6 weeks: normal control (NC),high fat (HF) andhigh fat supplemented with F100 (pure fibroin, HF-F100), F81 (81:19 fibroin-sericin, w/w, HF-F81) or F50 (50:50 fibroin-sericin, w/w, HF-F50). The silk protein-fed mice showed decreased lipid peroxidation, enhancedantioxidant enzymesactivities and lower blood glucose level relative to HF group. The HF-F50 animals exhibited significantly lower insulin level, higher glycogen concentration, enhanced hepatic glucokinaseactivity and reduced glucose-6-phosphate and phosphoenolpyruvatecarboxynaseactivities than the HF ones. The $in$ $vivo$ antioxidant activity and hypoglycemic action tended to increase with increased amount of sericin and decreased fibroin content in the diet. These findings demonstrate that silk protein, particularly sericin, may be beneficial in suppressing high fat diet-induced hyperglycemiaand oxidative stress.