Fucosterol, isolated from Ecklonia stolonifera, inhibits adipogenesis through modulation of FoxO1 pathway in 3T3-L1 adipocytes

Objectives: The purpose of this study was to investigate the effects of fucosterol on adipogenesis of 3T3-L1 preadipocytes and its underlying mechanisms. Methods: Fucosterol, isolated from brown algae, Ecklonia stolonifera. We investigated the levels of lipid accumulation using Oil Red O staining. We conducted Western blot analysis to investigate regulatory effects of fucosterol on expression of phosphoinositide 3-kinase (PI3K), Akt, extracellular signal-regulated kinase (ERK), forkhead box protein O 1 (FoxO1) in 3T3-L1 adipocytes. Key findings: Fucosterol significantly reduced intracellular lipid accumulation of 3T3-L1 adipocytes at concentrations of 25 and 50 μm. Fucosterol downregulated insulin-triggered PI3K/Akt, and ERK pathways. It subsequently decreased expression of adipogenic transcription factors, including PPARγ, C/EBPα and SREBP-1. In addition, fucosterol enhanced SirT1 expression while decreased phospho-FoxO1 expression which resulted in the activation of FoxO1. Conclusions: We revealed that fucosterol inhibited adipogenesis of 3T3-L1 preadipocytes through modulation of FoxO signalling pathway. Therefore, our results suggest that fucosterol may be used for novel agents for the treatment of obesity.