Delphinidin, a major anthocyanin, inhibits 3T3-L1 pre-adipocyte differentiation through activation of Wnt/β-catenin signaling.

Delphinidin (Del) is a major anthocyanin that is widely found in pigmented fruits and vegetables. Herein, we investigated the antiadipogenic effect and the molecular mechanism by which Del affects 3T3-L1 preadipocyte differentiation. We found that Del effectively reduced intracellular lipid accumulation and promoted lipolysis while regulating the expression of adipogenic transcription factors and their target genes. This lipid lowering effect of Del was largely limited to the early phase of adipogenesis, which is governed by the delayed cell cycle progression due to G1 cell cycle arrest. Subsequently, Del suppressed the expression of early adipogenic transcription factors, such as C/EBPβ and C/EBPδ, as well as that of intermediate markers, C/EBPα, PPARγ, and the PPARγ-target adipocyte markers adiponectin and aP2 (FABP4). Furthermore, Del treatment activated Wnt1, Wnt10b, the Wnt receptor Fzd2, and the coreceptors Lrp5/6, while it inactivated Gsk3β, a member of the β-catenin destruction complex. Moreover, Del treatment stabilized cytoplasmic β-catenin levels and promoted its nuclear translocation, with subsequent activation of the expression of its downstream target genes, c-Myc and cyclin D1. Our findings therefore suggest that Del can effectively inhibit adipogenesis followed by the stabilization of β-catenin during early 3T3-L1 differentiation via inhibition of its destructive complexes and activation of Wnt signaling, and may thus be a promising candidate for the prevention of metabolic diseases, including obesity.