Viola mandshurica ethanolic extract prevents high-fat-diet-induced obesity in mice by activating AMP-activated protein kinase

• We investigated the anti-obesity effects of VME in high-fat diet-induced obese mice.
• VME reduced body weight, lipid accumulation, and serum lipid levels in obese mice.
• VME induced the activation of AMPK and the suppression of PPARγ in adipose tissue.
• HPLC analysis showed that VME contained 11.95 ± 0.37 mg/g esculetin and 0.13 ± 0.01 mg/g scopoletin.

Viola mandshurica W. Becker has been used as an expectorant, diuretic, and anti-inflammatory agent. We evaluated the effects of V. mandshurica ethanol extract (VME) on high-fat-diet (HFD)-induced obesity in mice. HPLC analysis showed that the VME contained 11.95 ± 0.37 mg/g esculetin and 0.13 ± 0.01 mg/g scopoletin. Orally administered VME decreased the body weight, adipose tissue mass, adipocyte size, and triglyceride and leptin serum concentrations. In contrast, VME increased serum adiponectin concentrations and adiponectin expression levels in epididymal adipose tissues. VME also significantly reversed the HFD-induced elevation of the mRNA and protein levels of lipogenic genes such as peroxisome proliferator-activated receptor γ, sterol regulatory element-binding protein-1c, fatty-acid synthase, and adipocyte protein 2. Moreover, VME reversed the HFD-induced inhibition of AMP-activated protein kinase (AMPK) and acetyl-coA carboxylase phosphorylation in epididymal adipose tissues. Furthermore, treatment of VME and esculetin in 3T3-L1 cells inhibited adipocyte differentiation and fat accumulation. These results suggest that VME exerts anti-obesity effects in HFD-induced obese mice by activating AMPK and suppressing PPARγ expression in adipose tissues.