Rubi Fructus (Rubus coreanus) Inhibits Differentiation to Adipocytes in 3T3-L1 Cells

Rubi Fructus (RF) is known to exert several pharmacological effects including antitumor, antioxidant, and anti-inflammatory activities. However, its antiobesity effect has not been reported yet. This study was focused on the antidifferentiation effect of RF extract on 3T3-L1 preadipocytes. When 3T3-L1 preadipocytes were differentiating into adipocytes, 10–100 μg/mL of RF was added. Next, the lipid contents were quantified by Oil Red O staining. RF significantly reduced lipid accumulation and downregulated the expression of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT0-enhancer-binding proteins α (C/EBPα), adipocyte fatty acid-binding protein 2 (aP2), resistin, and adiponectin in ways that were concentration dependent. Moreover, RF markedly upregulated liver kinase B1 and AMP-activated protein kinase (AMPK). Interestingly, pretreatment with AMPKα siRNA and RF downregulated the expression of PPARγ and C/EBPα protein as well as the adipocyte differentiation. Our study shows that RF is capable of inhibiting the differentiation of 3T3-L1 adipocytes through the modulation of PPARγ, C/EBPα, and AMPK, suggesting that it has a potential for therapeutic application in the treatment or prevention of obesity.