Inhibitory effect of sinigrin on adipocyte differentiation in 3T3-L1 cells: Involvement of AMPK and MAPK pathways

Adipocyte differentiation is a critical adaptive response to nutritional overload and affects the metabolic outcome of obesity. Sinigrin (2-propenyl glucosinolate) is a glucosinolate belong to the glucoside contained in broccoli, brussels sprouts, and black mustard seeds. We investigated the effects of sinigrin on adipogenesis in 3T3-L1 preadipocytes and its underlying mechanisms. Sinigrin remarkably inhibited the accumulation of lipid droplets and adipogenesis by downregulating the expression of CCAAT-enhancer-binding protein α (C/EBPα), Peroxisome Proliferator-activated Receptor gamma (PPARγ), Leptin and aP2. Sinigrin arrested cells in the G₀/G₁ phase of the cell cycle and increased the expression of p21 and p27. CDK2 expression was suppressed by sinigirn in MDI-induced adipocytes. Sinigrin increased the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK) and Acetyl-CoA Carboxylase (ACC) in the early stage of adipocyte differentiation, suggesting that sinigrin has anti-adipogenic effects through AMPK, MAPK and ACC activation. Sinigrin also inhibited the production of pro-inflammatory cytokines including tumor necrosis factor -alpha (TNF-α) and interleukin (IL)-6, IL-1β and IL-18. Taken together, these data suggest that sinigrin inhibits early-stage adipogenesis of 3T3-L1 adipocytes through the AMPK and MAPK signaling pathways.