Effects of a sweetpotato protein digest on lipid metabolism in mice administered a high-fat diet.

Sweetpotato peptide (SPP) was prepared by enzyme digestion of sweetpotato protein from starch wastewater. Animal experiments assessed the effect of SPP on body weight, abdominal adipose tissue mass, serum lipids and adipocytokines. Body and liver weight and epididymal and mesenteric fat of mice fed a high-fat diet containing 0.5% or 5% SPP for 28 days were significantly lower than control mice. Triglyceride and cholesterol in VLDL and LDL and leptin levels were significantly lower in the serum of SPP-administered mice compared to control mice. Biomarker arrays showed that adiponectin, melanocyte-stimulating-hormone-alpha and neuromedin U were more than 1.5 times higher, while TNF-alpha was about 1.5 times lower in the livers of SPP-administered mice compared to control mice. These results suggest SPP mitigated leptin resistance in mice administered a high-fat diet, and maintained anorexigenic peptide levels. SPP administration may suppress lipogenesis by increasing adiponectin levels and decreasing TNF-alpha levels in adipocytes.