Isolation and identification of α-glucosidase inhibitory constituents from the seeds of Vigna nakashimae: Enzyme kinetic study with active phytochemical

• Published in: Food chemistry Vol. 266; pp. 483 - 489
• Main Authors: Ha, Tae Joung, Bo Song, Seok, Ko, Jeeyeon, Park, Chang-Hwan, Ko, Jong-Min, Choe, Myeong-Eun, Kwak, Do-Yeon, Lee, Jin Hwan
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.11.2018
• Subjects: Aldose reductase; alpha-Glucosidases - chemistry; alpha-Glucosidases - metabolism; Catechin - analogs & derivatives; Catechin - chemistry; Catechin - isolation & purification; Catechin - metabolism; Gambiriin D; Glycoside Hydrolase Inhibitors - chemistry; Glycoside Hydrolase Inhibitors - isolation & purification; Glycoside Hydrolase Inhibitors - metabolism; Inhibitory Concentration 50; Kinetics; Magnetic Resonance Spectroscopy; Molecular Conformation; Phenols - chemistry; Phenols - isolation & purification; Phenols - metabolism; Phytochemicals - chemistry; Phytochemicals - isolation & purification; Phytochemicals - metabolism; Plant Extracts - chemistry; Reversible slow-binding inhibition; Saccharomyces cerevisiae - enzymology; Seeds - chemistry; Seeds - metabolism; Vigna - chemistry; Vigna - metabolism; Vigna nakashimae; α-Glucosidase; Catechin-7-O-glucopyranoside (PubChem CID: 44257085); Vigna nakashimae; α-Glucosidase; Aldose reductase; Reversible slow-binding inhibition; Gambiriin D; Gambiriin D and luteoliflavan-7-O-glucopyranoside were not found in PubChem compound
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2018.06.039

•V. nakashimae seeds showed potent α-glucosidase inhibition (IC50 = 7.3 ± 1.1 μg/ml).•Three phenolic compounds were identified from the seeds of V. nakashimae.•Gambiriin D inhibited α-glucosidase with reversible slow-binding mode (IC50 = 36.8 ± 2.3 μM).•Gambiriin D inhibited human aldose reductase with IC50 value of 12.0 ± 0.7 μM. The α-glucosidase inhibition effects of the 80% ethanol extracts in the seeds of five Vigna species (V. nakashimae, V. nipponensis, V. umbellate, V. radiate, and V. angularis) were evaluated and their half-maximal inhibitory concentration (IC50) values showed considerable differences (p < 0.05) ranging from 7.3 to >900 μg/ml. V. nakashimae exhibited the most potent inhibition with IC50 value of 7.3 ± 1.1 μg/ml, followed by V. nipponensis (184.0 ± 9.5 μg/ml) and V. umbellata (520.0 ± 8.1 μg/ml). Bioactivity-guided fractionation of V. nakashimae seeds yielded three phenolics by silica gel chromatography and their structures were elucidated as gambiriin D (1), luteoliflavan-7-O-glucopyranoside (2), and catechin-7-O-glucopyranoside (3) using nuclear magnetic resonance (NMR) spectroscopy. In particular, gambiriin D (1) possessed strong inhibition activity with IC50 of 36.8 ± 2.3 μM through simple reversible slow-binding inhibition (kinetic parameters: k4 = 0.0048  μM−1s−1; Kiapp = 48 μM). Furthermore, this compound inhibited recombinant human aldose reductase with IC50 value of 12.0 ± 0.7 μM. Results suggest that V. nakashimae may be a potent α-glucosidase inhibition for health products.