Fucoidans from Thelenota ananas with 182.4 kDa Exhibited Optimal Anti-Adipogenic Activities by Modulating the Wnt/β-Catenin Pathway

In this study, fucoidans were extracted from the sea cucumber Thelenota ananas (Ta-FUCs) by enzymatic degradation. Four products with molecular weights of 1380.3, 524.0, 182.4, and 110.3 kDa were obtained, and the Ta-FUC showing optimal anti-adipogenic activities was determined. Results of MTT and Oil red O staining analyses showed that the Ta-FUCs inhibited the proliferation and differentiation of 3T3-L1 adipocytes. Futhermore, Ta-FUCs significantly downregulated the key transcriptional factors, such as SREBP-1c, PPARγ, and C/EBPα of adipocytes. The Ta-FUCs also activated Wnt/β-catenin pathway-related genes, such as β-catenin, LRP5, and FrZ. The Ta-FUCs suppressed lipid accumulation in 3T3-L1 adipocytes possibly by decreasing the expression of genes ACC, FAS, ME, GPAT, DGAT, and PILN, which are important in the synthesis of fatty acids and triglycerides; and by increasing the expression of genes PPARα, CPT-1α, and ACOX, which are crucial in fatty acid β-oxidation. The anti-adipogenic activities initially increased and then declined with decreasing molecular weight. Among the Ta-FUCs, the 182.4 kDa Ta-FUC exhibited optimal bioactivities. This study reports for the first time that Ta-FUCs can prevent obesity by regulating the differentiation and lipid accumulation of adipocytes.