Foenumoside B from Lysimachia foenum-graecum inhibits adipocyte differentiation and obesity induced by high-fat diet

We have previously reported anti-obesity effects of Lysimachia foenum-graecum in high-fat diet (HFD)-induced obesity model. Here we isolated a triterpene saponin foenumoside B as an active component of L. foenum-graecum. Foenumoside B blocked the differentiation of 3T3-L1 preadipocytes in a dose-dependent manner with an IC50 of 0.2 μg/ml in adipogenesis assay and suppressed the induction of PPARγ, the master regulator of adipogenesis. Foenumoside B induced the activation of AMP-activated protein kinase (AMPK), and modulated the expression of genes involved in lipid metabolism towards lipid breakdown in differentiated adipocytes. In mouse model, oral administration of foenumoside B (10mg/kg/day for 6 weeks) reduced HFD-induced body weight gain significantly without affecting food intake. Treatment of foenumoside B suppressed lipid accumulation in white adipose tissues and the liver, and lowered blood levels of glucose, triglycerides, ALT, and AST in HFD-induced obese mice. Consistent with the in vitro results, foenumoside B activated AMPK signaling, suppressed the expression of lipogenic genes, and enhanced the expression of lipolytic genes in vivo. Foenumoside B also blocked HFD-induced proinflammatory cytokine production in adipose tissue, suggesting its protective role against insulin resistance. Taken together, these findings demonstrate that foenumoside B represents the anti-obesity effects of L. foenum-graecum, and suggest therapeutic potential of foenumoside B in obesity and obesity-related metabolic diseases.