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

TL;DR

Adzuki beans contain new compounds that strongly inhibit enzymes linked to diabetes and obesity, suggesting their potential as functional food ingredients.

Contribution

A new triterpenoid saponin and three compounds first reported in adzuki beans were identified as potent dual enzyme inhibitors.

Findings

Adzukisaponin A and related saponins strongly inhibited pancreatic lipase and α-glucosidase more effectively than orlistat.

Molecular docking confirmed the compounds bind to the active sites of both enzymes.

The flavonoid compound 8 also showed significant inhibitory activity against both enzymes.

Abstract

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.

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