Chemical Properties of Vitis Vinifera Carménère Pomace Extracts Obtained by Hot Pressurized Liquid Extraction, and Their Inhibitory Effect on Type 2 Diabetes Mellitus Related Enzymes

Abstract

Grape pomace polyphenols inhibit Type 2 Diabetes Mellitus (T2DM)-related enzymes,reinforcing their sustainable recovery to be used as an alternative to the synthetic drug acarbose.Protic co-solvents (ethanol 15% and glycerol 15%) were evaluated in the hot pressurized liquidextraction (HPLE) of Carménère pomace at 90, 120, and 150 ?C in order to obtain extracts rich inmonomers and oligomers of procyanidins with high antioxidant capacities and inhibitory effectson ?-amylase and ?-glucosidase. The higher the HPLE temperature (from 90 ?C to 150 ?C) thehigher the total polyphenol content (~79%, ~83%, and ~143% for water-ethanol, water-glyceroland pure water, respectively) and antioxidant capacity of the extracts (Oxygen Radical AbsorbanceCapacity, ORAC), increased by ~26%, 27% and 13%, while the half maximal inhibitory concentration(IC50) decreased by ~65%, 67%, and 59% for water-ethanol, water-glycerol, and pure water extracts,respectively). Water-glycerol HPLE at 150 and 120 ?C recovered the highest amounts of monomers(99, 421, and 112 µg/g dw of phenolic acids, flavanols, and flavonols, respectively) and dimers ofprocyanidins (65 and 87 µg/g dw of B1 and B2, respectively). At 90 ?C, the water-ethanol mixtureextracted the highest amounts of procyanidin trimers (13 and 49 µg/g dw of C1 and B2, respectively)and procyanidin tetramers of B2 di-O-gallate (13 µg/g dw). Among the Carménère pomace extractsanalyzed in this study, 1000 µg/mL of the water-ethanol extract obtained, at 90 ?C, reduced differentially the ?-amylase (56%) and ?-glucosidase (98%) activities. At the same concentration, acarboseinhibited 56% of ?-amylase and 73% of ?-glucosidase activities; thus, our grape HPLE extracts canbe considered a good inhibitor compared to the synthetic drug.