Immature sword bean pods (Canavalia gladiata) inhibit adipogenesis in C3H10T1/2 cells and mice with high-fat diet-induced obesity

Background: Sword bean (SB; Canavalia gladiata) is a perennial vine used as a food and medicinal plant in Asia. SB is rich in nutrients, such as flavonoids and urease, and has various functions, including beneficial effects on dysentery, nausea, and hemorrhoids, as well as anti-inflammatory and antioxidant activity. Various plant parts are used; however, little is known about the physiological effects of SB pods (SBP). In this study, the anti-obesity effects of SBP extract were evaluated. Methods: To investigate the anti-obesity effects of SBP extract, we confirmed the SBP extract downregulated lipogenesis-related genes and upregulated genes involved in lipolysis and brown adipocyte markers in differentiated C3H10T1/2 adipocytes in vitro. Next, we use a high-fat diet (HFD)-induced obesity mouse model to determine the anti-obesity effects of SBP extract. Results: Treatment with SBP extract significantly reduced adipocytes. The extract decreased the HFD-induced increases in body weight and plasma triglyceride levels in mice after 8 weeks. mRNA and protein levels of the adipogenesis and lipogenesis-related factors CCAAT/enhancer binding protein-beta, CCAAT/enhancer binding protein-alpha, peroxisome proliferator-activated receptor-gamma (PPAR gamma), and their target genes Ap2, SREBP-1c, FAS, and SCD-1 were reduced by SBP extract. In contrast, AMP-activated protein kinase and sirtuin1, involved in the thermogenic catabolism of fat, were activated by SBP extract in adipocytes and white adipose tissue, increasing the expression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha, peroxisome proliferator-activated receptor-alpha (PPAR alpha), and uncoupling protein 1 and activating thermogenic activity. Conclusion: SBP extract exerts an anti-obesity effect by inhibiting lipogenesis-related factors and activating fat-catabolizing factors; it is, therefore, a promising functional food and natural anti-obesity agent.