Anti-adipogenic effect of dioxinodehydroeckol via AMPK activation in 3T3-L1 adipocytes

Dioxinodehydroeckol (DHE) isolated from Ecklonia cava, has previously been investigated for its inhibition of the differentiation of 3T3-L1 preadipocytes into adipocytes. Levels of lipid accumulation were measured, along with changes in the expression of genes and proteins associated with adipogenesis and lipolysis. Confluent 3T3-L1 preadipocytes in medium with or without different concentrations of DHE for 7 days were differentiated into adipocytes. Lipid accumulation was quantified by measuring direct triglyceride contents and Oil-Red O staining. The expression of genes and proteins associated with adipogenesis and lipolysis was measured using RT-PCR, quantitative real-time RT-PCR and Western blotting analysis. It was found that the presence of DHE significantly reduced lipid accumulation and down-regulated the expression of peroxisome proliferator-activated receptor-γ (PPARγ), sterol regulatory element-binding protein 1 (SREBP1) and CCAAT/enhancer-binding proteins (C/EBPα) in a dose-dependent manner. Moreover, DHE suppressed regulation of the adipocyte-specific gene promoters such as fatty acid binding protein (FABP4), fatty acid transport protein (FATP1), fatty acid synthase (FAS), lipoprotein lipase (LPL), acyl-CoA synthetase 1 (ACS1), leptin, perilipin and HSL compared to control adipocytes. The specific mechanism mediating the effects of DHE was confirmed by activation of phosphorylated AMP-activated protein kinase (pAMPK). Therefore, these results suggest that DHE exerts anti-adipogenic effect on adipocyte differentiation through the activation and modulation of the AMPK signaling pathway.