?-Glucosidase Inhibitory Activity of Tannat Grape Phenolic Extracts in Relation to Their Ripening Stages.
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ABSTRACT: The present study aimed to screen grape extracts as novel ?-glucosidase inhibitors to prevent type-2 diabetes and hyperglycemia. The total polyphenol content (TPC) was measured by Folin-Ciocalteu assay and the stilbene, anthocyanin and flavan-3-ol compounds were measured by Ultra High-Performance Liquid Chromatography coupled to Mass Spectrometry (UHPLC-MS). The ?-glucosidase inhibitory of seed and skin Tannat grape extracts at four ripening stages were investigated. The highest TPC values were measured in seeds at the "veraison stage" (65.29 ± 5.33 g of Gallic Acid Equivalent (GAE) per kilogram of Fresh Weight (FW)). This was in accordance with the high flavan-3-ol contents measured for these two extracts (43.22 ± 2.59 and 45.45 ± 6.48 g/kg of seeds FW, respectively). The skin and seed extracts at the first stage of ripening exerted strong ?-glucosidase inhibition, exceeding 95% (p < 0.05). A high linear correlation (R = 0.723, p ? 0.05) was observed between flavan-3-ol contents and the ?-glucosidase inhibitory activity. The stilbene contents and this activity were moderately to strongly anti-correlated (R = -0.828, p ? 0.05 for trans-resveratrol). The enzyme kinetic studies revealed a mixed type of inhibition. This study brings promising results for the therapeutic potential of seed and skin Tannat grape extracts as a functional food product with anti-diabetic activity.
SUBMITTER: Dudoit A
PROVIDER: S-EPMC7464188 | biostudies-literature | 2020 Jul
REPOSITORIES: biostudies-literature
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