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Characteristics of proanthocyanidins in leaves of Chamaecyparis obtusa var. formosana as strong α ‐glucosidase inhibitors
Author(s) -
Hsu ChiaYun,
Lin GongMin,
Lin HuanYou,
Chang ShangTzen
Publication year - 2018
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.8894
Subject(s) - proanthocyanidin , chemistry , sephadex , postprandial , food science , biochemistry , enzyme , polyphenol , biology , antioxidant , insulin , endocrinology
BACKGROUND In recent decades, there has been a growing demand for natural products with a view to using them as α ‐glucosidase inhibitors for reducing postprandial hyperglycemia. In this study, the hot water extract (HWE) from Chamaecyparis obtusa var. formosana (Hayata) Rehder (Cupressaceae) leaves and its soluble fractions were screened for α ‐glucosidase inhibition properties. The n ‐butanol‐soluble fraction of HWE was further fractionated into 14 subfractions (B1–B14) using a Sephadex LH‐20 column. The α ‐glucosidase‐inhibitory activities and proanthocyanidin contents of all subfractions were determined. The structural characteristics of proanthocyanidins in proanthocyanidin‐rich fractions were also elucidated. RESULTS HWE produced a dose‐dependent inhibition of α ‐glucosidase at low dose. Its IC 50 value was 1.4 µg mL −1 , showing high inhibitory activity. Subfractions B7–B14 displayed powerful α ‐glucosidase‐inhibitory activities with IC 50 values ranging between 1 and 0.015 µg mL −1 and contained abundant proanthocyanidins exceeding 300 mg g −1 . The proanthocyanidins with higher mean degree of polymerization (mDP), higher proportions of procyanidin dimer (A1 or A2) and ( epi )afzelechin of extension units and a lower proportion of epicatechin of terminal units displayed high α ‐glucosidase‐inhibitory activities. CONCLUSION Proanthocyanidins in HWE were viewed as potential natural α ‐glucosidase inhibitors for decreasing postprandial hyperglycemia. The results indicated that specific structural characteristics of proanthocyanidins would be required for α ‐glucosidase‐inhibitory activity. © 2018 Society of Chemical Industry