Mass Spectrometry and 1H-NMR Study of Schinopsis lorentzii (Quebracho) Tannins as a Source of Hypoglycemic and Antioxidant Principles
2020
Nunzio Cardullo | Vera Muccilli | Vincenzo Cunsolo | Corrado Tringali
The ethyl acetate extract of the commercial tannin Tan&rsquo:Activ QS-SOL (from Schinopsis lorentzii wood), employed for the production of red wine, was subjected to chromatography on Sephadex LH-20, providing nine fractions (A-1&ndash:A-9), which were estimated for total phenols content (GAE), antioxidant activity (DPPH, ORAC), and hypoglycemic activity (&alpha:-glucosidase and &alpha:-amylase inhibition). All the fractions were analyzed by means of HPLC/ESI-MS/MS and 1H-NMR to identify the principal active constituents. Fractions A-1 and A-3 showed the highest antioxidant activity and gallic acid (1), pyrogallol (3), eriodictyol (6), catechin (12), and taxifolin (30) were identified as the major constituents. The highest &alpha:-glucosidase and &alpha:-amylase inhibitory activity was observed in fractions A-7&ndash:A-9 containing condensed (9&prime:, 15, 18, 19, 23, and 27) hydrolysable tannins (13 and 32) as well as esters of quinic acid with different units of gallic acid (5, 11, 11&prime:, 14, and 22). This last class of gallic acid esters are here reported for the first time as &alpha:-glucosidase and &alpha:-amylase inhibitors.
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