The safety and availability of mackerel meat hydrolysate containing selenoneine in rats and mice

Selenoneine exhibited high antioxidant action compared to ergothioneine, a traditional antioxidant ingredient, whereas other selenium compounds such as selenious acid and seleno-L-methionine showed no antioxidative properties in several evaluations. We enzymatically prepared a hydrolysate of mackerel protein (EMP) containing selenoneine. EMP also exhibited antioxidant action in vitro. EMP treatment modulated the secretion of interleukin-6 and -10, but not TNF-α, in cultured RAW264.7 macrophages. The safety of EMP intake, i.e., selenium-feeding, was confirmed in SD rats. Serum and hepatic triglyceride levels and serum insulin, leptin, and cholesteryl ester levels tended to lower in SD rats fed EMP. The elevated serum triglyceride, free fatty acid, insulin, and leptin levels also tended to be decreased in KK-Ay mice fed EMP. These results suggest that EMP intake may be involved in the improvement of lipid metabolism, through immune modulation by the various antioxidants contained in EMP.