6,6′‐Bieckol inhibits adipocyte differentiation through downregulation of adipogenesis and lipogenesis in 3T3‐L1 cells

Abstract BACKGROUND Brown algae have been used for their nutritional value as well as a source of bioactive compounds with antioxidant, anti‐inflammatory, antimicrobial and anti‐obesity effects. Obesity is an important condition implicated in various diseases, including diabetes, hypertension, dyslipidemia and coronary heart disease. However, anti‐obesity effects of Eisenia bicyclis remain unknown. RESULTS We investigated the anti‐obesity effects of 6,6′‐bieckol, 6,8′‐bieckol, 8,8′‐bieckol, dieckol and phlorofucofuroeckol A isolated from E . bicyclis. Anti‐obesity activity was evaluated by examining the inhibition of differentiation of 3T3‐L1 adipocytes and the expression of peroxisome proliferator‐activated receptor γ ( PPARγ ), CCATT /enhancer‐binding protein α (C/ EBPα ) and sterol regulatory element binding protein‐1c ( SREBP ‐1c) at the mRNA and protein level. Differentiated 3T3‐L1 cells were treated with the purified phlorotannins at concentrations of 10, 25 and 50 µg mL −1 for 8 days. The results indicated that the purified phlorotannins suppressed the differentiation of 3T3‐L1 adipocytes in a dose–dependent manner, without toxic effects. Among the five compounds, 6,6′‐bieckol markedly decreased lipid accumulation and expression levels of PPARγ , C/ EBPα , SREBP ‐1c ( mRNA and protein), and fatty acid synthase and acyl‐ coA carboxylase ( mRNA ). CONCLUSION These findings suggest that E . bicyclis suppressed differentiation of 3T3‐L1 adipocyte through downregulation of adipogenesis and lipogenesis. © 2014 Society of Chemical Industry