Nat Prod Sci.  2022 Sep;28(3):143-152. 10.20307/nps.2022.28.3.143.

α-Glucosidase Inhibitory Activity of Phenolic Compounds Isolated from the Stems of Caesalpinia decapetala var. japonica

• Le TT
• Ha MT
• Hoang LM
• Vu NK
• Kim JA
• Min BS

• KMID: 2534113
• DOI: http://doi.org/10.20307/nps.2022.28.3.143

Abstract

In our study, sixteen known phenolic compounds, including quercetin (1), methyl gallate (2), caesalpiniaphenol C (3), 8S,8′S,7′R-(‒)-lyoniresinol (4), 7,3′,5′-trihydroxyflavanone (5), sappanchalcone (6), sappanone A (7), taxifolin (8), fisetin (9), fustin (10), (+)-catechin (11), brazilin (12), 3,4,5-trimethoxyphenyl β-ᴅ-glucopyranoside (13), 1-(2-methylbutyryl)phloroglucinol-glucopyranoside (14), (+)-epi-catechin (15), and astragalin (16) and one mixture of two conformers of protosappanin B (17/18) were isolated from the stems of Caesalpinia decapetala var. japonica. Their structures were elucidated based on a comparison of their physicochemical and spectral data with those of literature. To the best of our knowledge, this represents the first isolation of compounds 3, 4, 8, 9, and 10 from C. decapetala and compounds 13 and 14 from the Caesalpinia genus. All the isolated compounds were evaluated for their inhibitory effect against the α-glucosidase enzyme. Among them, two flavonols (1 and 9), one chalcone (6), and one homoisoflavanone (7) exhibited an inhibitory effect on α-glucosidase action with an IC ₅₀ range value of 5.08 ‒ 15.01 µM, stronger than that of the positive control (acarbose, IC ₅₀ = 152.22 μM). Kinetic analysis revealed that compounds 1 and 9 showed non-competitive α-glucosidase inhibition, while the inhibition type was mixed for compounds 6 and 7.

Keyword

Caesalpinia decapetala var. japonica; Leguminosae; flavonoids; anti-diabetic; α-glucosidase