Meroterpenoid-Rich Fraction of the Ethanol Extract from Sargassum Serratifolium Suppressed Muscle Atrophy Induced by Dexamethasone in C2C12 Myotubes and C57BL/6 Mice

Decline in muscle mass and strength impairs the ability to perform normal daily functions and increases the risk of falls and fractures, significantly reducing the quality of life. In addition, as the muscle is considered a major regulator of systemic glucose homeostasis, maintaining muscle mass is important for glycemic control. Although dexamethasone (DEX), a synthetic glucocorticoid, is a well-known anti-inflammatory drug, high doses or long-term use induces side effects such as skeletal muscle atrophy. Sargassum serratifolium is a brown alga that contains high concentrations of meroterpenoids and exhibits antioxidant, anti-inflammatory, anti-obesity, anti-atherosclerosis, and hepatoprotective activities. However, its effects on DEX-induced muscle atrophy remain unknown. Here, we investigated the beneficial effects of the meroterpenoid-rich fraction of the ethanol extract from S. serratifolium (MES) on DEX-induced muscle atrophy in C2C12 myotubes and C57BL/6 mice. In the in vitro study using C2C12 myotubes, DEX (5 μM) treatment reduced cell viability, myotube diameter, and glucose uptake, whereas MES treatment reversed these effects. In addition, in DEX-stimulated C2C12 myotubes, MES treatment not only increased the phosphorylation of Akt and p706SK but also decreased the mRNA and protein expression of protein degradation factors such as MAFbx/Atrogin-1, MuRF1, and FoxO3a. In the in vivo study, MES suppressed DEX-induced decrease in body weight, ability to exercise, lean body mass, calf thickness, muscle weight, and cross-sectional area of the gastrocnemius muscle. Taken together, MES ameliorated DEX-induced muscle atrophy and maintained glucose homeostasis. Therefore, MES can be used as a potential therapeutic agent for the treatment of muscle atrophy. Disclosure M.Lee: None. H.Ryu: None. H.Jeong: None. B.Lee: None.