α-Glucosidase and Pancreatic Lipase Inhibitory Activity of Chemical Constituents from Adzuki Bean (Vigna angularis)

Originating in East Asia, the adzuki bean (Vigna angularis) is a diploid crop mainly grown in this region that belongs to the Fabaceae family. As a potential functional food resource with both medicinal and nutritional value, it offers various health benefits. However, research on its chemical constituents, particularly key bioactive components such as triterpenoid saponins and flavonoids, remains relatively limited. In this study, a new triterpenoid saponin, adzukisaponin A (1), along with eleven known compounds (2-12), were isolated from adzuki bean (V. angularis). Among them, compounds 3 (yunganoside B1), 6 (3β-acetyl oleanolic acid), and 7 (β-amyrin) are reported from this source for the first time. Saponins 1-3 and flavonoid 8 exhibited significant dual inhibitory activity. Notably, saponins 1-3 inhibited pancreatic lipase (IC₅₀ = 0.11 ± 0.18 to 0.40 ± 0.21 mM) more strongly than the positive control orlistat, while also acting against α-glucosidase (IC₅₀ = 0.14 ± 0.11 to 0.23 ± 0.17 mM). Molecular docking supported their binding to the enzymes' active sites. This study identifies 1-3 and 8 as dual α-glucosidase/pancreatic lipase inhibitors, underscoring the potential of adzuki bean as a source of bioactive functional food ingredients.