title: Inhibitory effects of polyphenols from water chestnut (Trapa japonica) husk on glycolytic enzymes and postprandial blood glucose elevation in mice.
abstract: Water chestnut is an annual aquatic plant that grows in Asia and Europe. Although water chestnut has been used as food and herbal medicine, its physiological functions and active ingredients are unknown. Here, we extracted polyphenols from the husk of the Japanese water chestnut (Trapa japonica) and assessed their effects on blood glucose levels. Three hydrolysable polyphenolics (WCPs), eugeniin, 1,2,3,6-tetra-O-galloyl-β-d-glucopyranose, and trapain, were predominant with dry-weight contents of 2.3 ± 0.0, 2.7 ± 0.1, and 1.2 ± 0.1g/100g, respectively. These WCPs exhibited inhibitory activity against α-amylase and α-glucosidase. Whereas (-)-epigallocatechin gallate does not inhibit α-amylase, WCPs exhibited high inhibitory activity (>80% at 0.15 mg/mL). In mice, administration of WCPs (40 mg/kg) significantly reduced blood glucose and serum insulin levels as assessed by the carbohydrate tolerance test.
authors.affiliation: Department of Health and Nutrition Science, Nishikyushu University, Kanzaki, Saga 842-8585, Japan. Electronic address: midori@nisikyu-u.ac.jp.
authors.forename: Midori
authors.initials: M
authors.lastname: Yasuda
authors.affiliation: Department of Health and Nutrition Science, Nishikyushu University, Kanzaki, Saga 842-8585, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Yasutake
authors.affiliation: Department of Health and Nutrition Science, Nishikyushu University, Kanzaki, Saga 842-8585, Japan.
authors.forename: Madoka
authors.initials: M
authors.lastname: Hino
authors.affiliation: Department of Health and Nutrition Science, Nishikyushu University, Kanzaki, Saga 842-8585, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Ohwatari
authors.affiliation: Department of Health and Nutrition Science, Nishikyushu University, Kanzaki, Saga 842-8585, Japan.
authors.forename: Nozomi
authors.initials: N
authors.lastname: Ohmagari
authors.affiliation: Department of Food and Nutrition, Nishikyushu University Junior College, Kamizono, Saga-shi, Saga 840-0806, Japan.
authors.forename: Kazumi
authors.initials: K
authors.lastname: Takedomi
authors.affiliation: Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-Machi, Nagasaki 852-8521, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Usaien Pharmaceutical Co. Ltd., 1-4-6 Zaimoku, Saga 840-0055, Japan.
authors.forename: Gen-Ichiro
authors.initials: G
authors.lastname: Nonaka
mesh_terms: D000818:Animals; D008297:Male; D051379:Mice; D001786:Blood Glucose / Q000187:drug effects; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology; D010946:Plants, Medicinal / Q000737:chemistry; D059808:Polyphenols / Q000494:pharmacology; D019518:Postprandial Period; D029561:Lythraceae / Q000737:chemistry
chemical_list: D001786:Blood Glucose; D010936:Plant Extracts; D059808:Polyphenols
keywords: Blood glucose; Polyphenol; Trapa japonica; Water chestnut; α-Amylase; α-Glucosidase