Viburnum stellato-tomentosum Extract Suppresses Obesity and Hyperglycemia through Regulation of Lipid Metabolism in High-Fat Diet-Fed Mice

The potential biological activities of Viburnum stellato-tomentosum (VS), a plant mainly found in Costa Rica, have yet to be reported. Supplementation of VS extract for 17 weeks significantly decreased body weight gain, fat weight, fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and triglyceride levels in high-fat diet (HFD)-fed C57BL/6J mice. The molecular mechanisms underlying the anti-obesity and glucose-lowering effects of VS extract were investigated. VS extract suppressed adipocyte hypertrophy by regulating lipogenesis-related CCAAT/enhancer-binding protein alpha (C/EBP alpha) and insulin sensitivity-related peroxisome proliferator-activated receptor gamma (Pparg) expression in adipose tissue (AT) and hepatic steatosis by inhibiting C/EBP alpha and lipid transport-related fatty acid binding protein 4 (FABP4) expression. VS extract enhanced muscular fatty acid beta-oxidation-related AMP-activated protein kinase (AMPK) and PPAR alpha expression with increasing Pparg levels. Furthermore, VS extract contained a much higher content of amentoflavone (AMF) (29.4 mg/g extract) compared to that in other Viburnum species. AMF administration decreased Cebpa and Fabp4 levels in the AT and liver, as well as improved insulin signaling-related insulin receptor substrate 1 (Irs1) and glucose transporter 1 (Glut1) levels in the muscle of HFD-fed mice. This study elucidated the in vivo molecular mechanisms of AMF for the first time. Therefore, VS extract effectively diminished obesity and hyperglycemia by suppressing C/EBP alpha-mediated lipogenesis in the AT and liver, enhancing PPAR alpha-mediated fatty acid beta-oxidation in muscle, and PPAR gamma-mediated insulin sensitivity in AT and muscle.

Automated summary

This study found that the Viburnum stellato-tomentosum extract can reduce obesity and high blood sugar by regulating gene expression related to lipogenesis and fatty acid oxidation, while improving insulin sensitivity.