Extraction of Antioxidants from Winemaking Byproducts: Effect of the Solvent on Phenolic Composition, Antioxidant and Anti-Cholinesterase Activities, and Electrochemical Behaviour.

María José Jara-Palacios,Sandra Gonçalves,Francisco J Heredia,Dolores Hernanz,Anabela Romano

doi:10.3390/antiox9080675

María José Jara-Palacios, Sandra Gonçalves + Show 3 more

Open Access

https://doi.org/10.3390/antiox9080675

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Abstract

Extraction solvent is a very important factor in the recovery of antioxidants from natural matrices. In this study, the effect of three solvents (ethanol, ethanol/water and water) on the phenolic composition, antioxidant and anti-cholinesterase activities and electrochemical behaviour of four winemaking byproducts (seeds, skins, stems, and pomace) was evaluated. Phenolic composition was determined by the Folin–Ciocalteu method and ultra-high-performance liquid chromatography (UHPLC), antioxidant activity by the capacity to scavenge 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radicals, anti-cholinesterase activity by the Ellman’s method, and electrochemical behaviour by cyclic voltammetry. Eight phenolic compounds were quantified with higher content in water/ethanol extracts (e.g., epicatechin in pomace: 17 mg/100 g vs. 7 and 6 mg/100 g in ethanol and water extracts, respectively), although there were some exceptions (e.g., gallic acid in seeds was most abundant in water extracts). Moreover, the highest total phenolic content (TPC) and antioxidant activity were found in ethanol/water extracts (between 2 and 30-fold the values of the other extracts). Overall, the most active extracts in inhibiting both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes were ethanol/water and ethanol extracts from seeds (between 31.11 and 53.90%). The electrochemical behaviour allowed for differentiating the extracts depending on the solvent and the byproduct. Our findings indicate that winemaking byproducts represent a source of phenolic compounds with antioxidant and anti-cholinesterase activities and suggest that cyclic voltammetry is a promising technique to evaluate the phenolic extraction process from these byproducts.

Highlights

Antioxidants are artificial or natural chemical substances that delay the oxidation of proteins, DNA and lipids, due to their properties, and can counteract oxidative stress [1]
The extraction yields expressed as weight of phenolic extract relative to the weight of the initial
Winemaking is an activity that leads to the generation of large amounts of byproducts, such as grape pomace, rich in phenolic compounds

Summary

Introduction

Antioxidants are artificial or natural chemical substances that delay the oxidation of proteins, DNA and lipids, due to their properties, and can counteract oxidative stress [1]. Antioxidants 2020, 9, 675 cells and tissues of the living organisms [2,3]. This oxidative damage is related to the physiopathology of many diseases, such as cancer, atherosclerosis, cardiovascular, metabolic and neurodegenerative diseases, and brain ageing [2,3,4,5,6]. Neurodegenerative diseases are related to oxidative stress [7,8]. These diseases are characterised by alterations in the concentration and activity of an important neurotransmitter namely acetylcholine [9]. A specific treatment is based on increasing the concentration of acetylcholine by inhibiting the activity of acetylcholinesterase (AChE) and butylcholinesterase (BChE), which are key enzymes in the breakdown of this neurotransmitter [10]

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