Chestnut astringent skin extract, an alpha-amylase inhibitor, retards carbohydrate absorption in rats and humans.
Inhibitors of carbohydrate-hydrolyzing enzyme play an important role to control postprandial blood glucose levels. In this paper, we investigated the effect of an ethanol extract from chestnut astringent skin (CAS) on alpha-amylase. Chestnut astringent skin extract strongly inhibited human and porcine pancreatic alpha-amylase. We also investigated the effect of CAS extract on carbohydrate absorption in rats and humans. Oral administration of CAS extract to normal rats fed corn starch (2 g/kg body weight), significantly suppressed the increase of blood glucose levels after starch loading in a dose-dependent manner. The effective dose of CAS extract required to achieve 20 and 40% suppression of the rise in blood glucose level was estimated to be 40 and 155 mg/kg body weight, respectively. Chestnut astringent skin extract also suppressed the rise in plasma insulin level and the fall in plasma non-esterified fatty acid level. In the type 2 diabetic rat model, CAS extract significantly suppressed the rise in blood glucose level after starch loading in a dose-dependent manner. Chestnut astringent skin extract also suppressed the rise in plasma glucose level after boiled rice loading in a dose-dependent manner in humans. The amount of CAS extract required to achieve 11 and 23% suppression in the rise in plasma glucose level was 300 and 600 mg/person, respectively. These results suggest that CAS extract retards absorption of carbohydrate and reduces post-prandial hyperglycemia.
Tsujita
Takahiro
T
Bioscience, Integrated Center for Sciences, Ehime University, Ehime, Japan. tsujita@m.ehime-u.ac.jp
Takaku
Takeshi
T
Suzuki
Tsuneo
T
D000328:Adult; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006801:Humans; D006943:Hyperglycemia / Q000517:prevention & control; D007408:Intestinal Absorption / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D009754:Nuts; D008517:Phytotherapy / Q000379:methods; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D019518:Postprandial Period / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013552:Swine; D014197:Trees; D000516:alpha-Amylases / Q000037:antagonists & inhibitors* / Q000737:chemistry
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004791:Enzyme Inhibitors; D010936:Plant Extracts; D000516:alpha-Amylases