Saponins are responsible for the anti-obesogenic activity of Acacia concinna

Acacia concinna (Willd.) DC. is a medicinal plant sourced mainly from Southeast Asia. The pods of Acacia concinna (A. concinna) are a potential candidate to treat or prevent obesity; however, these medicinal attributes have not been examined in detail. In this study, the anti-obesogenic compounds in A. concinna pods were investigated. Chromatographic separation of the pod extract guided by pancreatic lipase inhibitory activity led to the isolation of saponins. Decomposition analysis of the saponins revealed their chemical composition to be acacic acid, monoterpenes, and five types of sugars (glucose, xylose, rhamnose, quinovose, arabinose). The predicted structures of the saponins from decomposition analysis were confirmed by LC-MS analysis, showing that these saponins are mixture of various derivatives of monoterpenes and sugar units. These saponins inhibited pancreatic lipase activity strongly with an IC₅₀ of 7.9 μg/mL, and reduced lipid accumulation in 3T3-L1 adipocytes at 6.3 μg/mL. The saponins also enhanced lipolysis of 3T3-L1 adipocytes at 3.1 or 6.3 μg/mL by mediating the activity of protein kinase A and extracellular signal-regulated kinase pathways, suggesting that this mechanism is partly responsible for the observed reduction of lipid content in adipocytes. The results underline A. concinna as a potential source of the anti-obesogenic candidates for the future treatment and prevention of obesity.