Raspberry ketone, a naturally occurring phenolic compound, inhibits adipogenic and lipogenic gene expression in 3T3-L1 adipocytes.

Raspberry ketone (RK) is a natural phenolic compound of red raspberry. The dietary intake of RK has been reported to exert anti-obese actions and alter the lipid metabolism in vivo and human studies. To elucidate a possible mechanism for anti-obese actions of RK, the effects of RK on the adipogenic and lipogenic gene expression in 3T3-L1 adipocytes were investigated. 3T3-L1 maturing pre-adipocytes were treated from day 2 to day 8 of differentiation and mature adipocytes for 24 h on day 12 with 1, 10, 20, and 50 μM of RK. Triacylglycerols were assessed by spectrophotometry and gene expression by quantitative real-time polymerase chain reaction (qRT-PCR). Treatment of adipocytes with RK suppressed adipocyte differentiation and fat accumulation in a concentration-dependent manner. RK suppressed the expression of major genes involved in the adipogenesis pathway including peroxisome proliferator-activated receptor-γ (PPARγ) and CCAAT enhancer binding protein-α (C/EBPα), which led to further down-regulation of adipocyte fatty acid-binding protein-2 (aP2). In addition, treatment with 10 μM of RK also reduced mRNA levels of lipogenic genes such as acetyl-CoA carboxylase-1 (ACC1), fatty acid synthase (FASN), and stearoyl-CoA desaturase-1 (SCD1). In mature adipocytes, RK increased the transcriptional activities of genes involved in lipolysis and the oxidative pathways including adipose triglyceride lipase (ATGL), hormone sensitive lipase (HSL), and carnitine palmitoyl transferase-1B (CPT1B). These findings suggest that RK holds great promise for an herbal medicine with the biological activities altering the lipid metabolism in 3T3-L1 adipocytes.