Α-Glucosidase inhibition and antioxidant activity of an oenological commercial tannin. Extraction, fractionation and analysis by HPLC/ESI-MS/MS and 1H NMR. (15th January 2017)

• Record Type: Journal Article
• Authors: Muccilli, Vera; Cardullo, Nunzio; Spatafora, Carmela; Cunsolo, Vincenzo; Tringali, Corrado
• Is Part Of: Food chemistry. Volume 215(2017)
• Page Start: 50
• Page End: 60
• Publication Date: 2017-01-15
• Subjects: Plant polyphenols -- Oenological tannins -- Quercus robur -- α-Glucosidase inhibition -- HPLC/ESI-MS/MS -- 1H NMR; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2016.07.136
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: An oak wood oenological commercial tannin was extracted and fractionated on XAD-16. Fractions X1B and X2B showed enhanced antioxidant activity. Fractions X1C and X2C showed noticeable α-glucosidase inhibitory activity. The HPLC/ESI-MS/MS and 1 H NMR analyses allowed to identify the main constituents. Abstract: Two batches of the oenological tannin Tan'Activ R, (toasted oak wood – Quercus robur ), were extracted with ethanol. A fractionation on XAD-16 afforded four fractions for each extract. Extracts and fractions were evaluated for antioxidant activity (DPPH), polyphenol content (GAE) and yeast α-glucosidase inhibitory activity. Comparable results were obtained for both columns, fractions X1B and X2B showing the highest antioxidant activity. Fractions X1C and X2C notably inhibited α-glucosidase, with IC50 = 9.89 and 8.05 μg/mL, respectively. Fractions were subjected to HPLC/ESI-MS/MS and 1 H NMR analysis. The main phenolic constituents of both X1B and X2B were a monogalloylglucose isomer (1 ), a HHDP-glucose isomer (2 ), castalin (3 ) gallic acid (4 ), vescalagin (5 ), and grandinin (or its isomer roburin E, 6 ). X1C and X2C showed a complex composition, including non-phenolic constituents. Fractionation of X2C gave a subfraction, with enhanced α-glucosidase inhibitory activity (IC50 = 6.15 μg/mL), with castalagin (7 ) as the main constituent.