title: α-Amylase inhibitory activity from nut seed skin polyphenols. 1. Purification and characterization of almond seed skin polyphenols.
abstract: Using α-amylase inhibition as a separation guide, polyphenolic compounds from almond ( Prunus dulcis ) seed skin were purified using ultrafiltration and Sephadex LH-20 and ODS columns. The purified fraction specifically and strongly inhibited α-amylase; the IC50 value was 2.2 μg/mL for pig pancreatic α-amylase. The fraction contained about 62% of the total polyphenols, 33.8% flavanol-type tannins and 30% procyanidins. Oral administration of the polyphenol fraction to rats fed corn starch significantly suppressed an increase in blood glucose levels and area under the curve (AUC), in a dose-dependent manner. High-resolution MALDI-TOF mass spectra showed that the structure of this sample is a series of polyflavan-3-ol polymers composed of catechin/epicatechin units and gallocatechin/epigallocatechin units up to 11-mer with several interflavanoid ether linkages. The results suggest almond seed skin contains highly polymerized polyphenols with strong α-amylase inhibitory activity, which retard absorption of carbohydrate.
authors.affiliation: Bioscience, Integrated Center for Sciences, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan. tsujita@m.ehime-u.ac.jp
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsujita
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Shintani
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sato
mesh_terms: D000042:Absorption; D000596:Amino Acids; D000818:Animals; D019540:Area Under Curve; D044946:Biflavonoids / Q000737:chemistry / Q000494:pharmacology; D001786:Blood Glucose / Q000032:analysis; D002241:Carbohydrates / Q000037:antagonists & inhibitors / Q000493:pharmacokinetics; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D002857:Chromium; D003911:Dextrans / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D008297:Male; D009539:Nicotinic Acids; D009754:Nuts / Q000737:chemistry*; D055292:Pancreatic alpha-Amylases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D059808:Polyphenols / Q000737:chemistry* / Q000494:pharmacology; D044945:Proanthocyanidins / Q000737:chemistry / Q000494:pharmacology; D027861:Prunus / Q000737:chemistry*; D051381:Rats; D012639:Seeds / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013634:Tannins / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D044946:Biflavonoids; D001786:Blood Glucose; D002241:Carbohydrates; D003911:Dextrans; D004791:Enzyme Inhibitors; D009539:Nicotinic Acids; D010936:Plant Extracts; D059808:Polyphenols; D044945:Proanthocyanidins; D013634:Tannins; C015240:glucose tolerance factor; D002857:Chromium; C017674:procyanidin; D002392:Catechin; C025614:sephadex; D055292:Pancreatic alpha-Amylases; C057580:gallocatechol