Meroterpenoid-rich fraction of an ethanolic extract from Sargassum serratifolium alleviates obesity and non-alcoholic fatty liver disease in high fat-fed C57BL/6J mice

Sargassum serratifolium has diverse health-promoting effects because of high levels of meroterpenoids with strong antioxidant and anti-inflammatory activities. Here, we investigated the effects of a meroterpenoid-rich fraction of an ethanolic extract of S. serratifolium (MES) on obesity and obesity-related hepatic steatosis in high fat (HF)fed C57BL/6J mice. MES supplementation markedly reduced HF diet-induced obesity and hepatic steatosis without changes in food intake. MES improved blood lipid profile and elevated circulating adiponectin. Furthermore, MES notably increased uncoupling protein 1 (UCP-1)-positive cells and decreased macrophage infiltration in adipose tissue. MES exerted the anti-obesity and lipid-lowering effects by activating AMPK-related fatty acid oxidation signaling and inhibiting SREBP1c-related lipogenesis signaling in liver and adipose tissues. Our study indicates that MES prevents diet-induced obesity and related metabolic disorders at least partially by activating energy expenditure signaling and inhibiting lipogenesis. MES may be used as a pharmaceutical agent against obesity and related metabolic syndrome.