Effects of Sanyaku and Its Constituent Diosgenin on the Fasted and Postprandial Hypertriacylglycerolemia in High-Fat-Diet-Fed KK-AY Mice

In this study, we examined the fasted and postprandial triacylglycerol (TG) levels in ICK-A(Y) mice fed a high-fat diet (HFD) or a HFD containing either 500 ppm (0.05%) of diosgenin or 500 ppm (0.05%) of diosgenin-containing Chinese yam sanyaku. Oral fat tolerance tests revealed that, not only in the fasting state but also after loading of lipid emulsion, plasma levels of TG were significantly reduced in sanyaku- and diosgenin- fed mice. Levels of fat oxidation, especially in the dark phase (from 7 p.m. to 7 a.m.), were increased in the sanyaku and diosgenin groups. Moreover mRNA levels of lipoprotein lipase and peroxisome proliferator-activated receptor gamma, coactivator l alpha were moderately upregulated in the liver of sanyaku- and diosgenin-ingested mice. These results suggest that consecutive ingestion of diosgenin or diosgenin-containing sanyaku at the dose achievable in a human diet potentially ameliorates fasted and postprandial hypertriacylglycerolemia, which could be associated with the improvement of TG metabolism.