New Insights into the Exploitation of Vitis vinifera L. cv. Aglianico Leaf Extracts for Nutraceutical Purposes.

Maria Rosaria Nolè,Fabiana Labanca,Ruth Hornedo-Ortega,Lucia Chiummiento,Maria Carmen García-Parrilla,Daniela Russo,Luigi Milella,Immacolata Faraone,Maria Grazia Bonomo

doi:10.3390/antiox9080708

Abstract

The leaves of Vitis vinifera L. have been used for a long time in traditional medicine for the treatment of many ailments. Grape polyphenols, indeed, have been demonstrated to be able to defend against oxidative stress, responsible for various disorders such as cancer, diabetes and neurodegenerative diseases. The effects of different extraction techniques, Soxhlet (SOX), Accelerated Solvent (ASE 40, ASE 50) and Ultrasound Assisted Extraction (UAE) were studied in this work to evaluate their impact on the chemical profile and bioactive potential of Vitis vinifera L. (cv. Aglianico) leaf extracts. The phytochemical profile was investigated by HPLC-DAD and 9 phenolic compounds were identified and quantified in the extract. Moreover, the antioxidant, anticholinesterase and antityrosinase activities were evaluated. In detail, the total polyphenol content and antioxidant activity (2,2-diphenyl-1-picrylhydrazyl, Oxygen Radical Absorbance Capacities and β-Carotene Bleaching assays) were evaluated and compared to assess the Relative Antioxidant Capacity Index (RACI). To test the inhibitory activity of extracts towards cholinesterases, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition assays were performed. SOX and ASE 50 have shown the highest value of RACI, 0.76 and 0.65, respectively. Regarding enzymatic inhibitory activity, ASE 50 (IC50 = 107.16 ± 8.12 μg/mL) and SOX (IC50 = 171.34 ± 12.12 μg/mL) extracts exhibited the highest AChE and BChE inhibitory activity, respectively, while UAE (IC50 = 293.2 ± 25.6 μg/mL, followed by SOX (IC50 = 302.5 ± 38.3 μg/mL) showed the highest tyrosinase inhibition value. Our results demonstrated for the first time that Aglianico leaves are important sources of phenols that could be used to prevent oxidative stress and be potentially helpful in diseases treatable with tyrosinase and cholinesterase inhibitors, like myasthenia gravis or Alzheimer’s.

Highlights

Grapevine is one of the most widely cultivated plants in the world, with a global annual production of nearly 80 million tons in 2018 [1], destined for different purposes
Our results demonstrated for the first time that Aglianico leaves are important sources of phenols that could be used to prevent oxidative stress and be potentially helpful in diseases treatable with tyrosinase and cholinesterase inhibitors, like myasthenia gravis or Alzheimer’s
Analytical grade methanol and acetonitrile were obtained from Merck (Darmstadt, Germany and Mollet del Vallés, Spain); 2,2-diphenyl-1-picryl hydrazyl (DPPH) in free radical form, 2,20 -azobis(2-amidinopropane) dihydrochloride (AAPH), Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic), trizma hydrochloride (Tris-HCl), bovine serum albumin (BSA), Folin-Ciocalteu’s phenol reagent, β-carotene, linoleic acid, Tween 20, butylated hydroxytoluene (BHT, 2,6-bis (1,1-dimethylethyl)-4-methylphenol), 5,50 -dithio-bis (2-nitrobenzoic acid) (DTNB), acetylcholinesterase (AChE) from electric eel, acetylthiocholine iodide (ATCI), butyrylcholinesterase (BChE) from equine serum and S-butyrylthiocholine chloride (BTCC), were purchased from Sigma

Summary

Introduction

Grapevine is one of the most widely cultivated plants in the world, with a global annual production of nearly 80 million tons in 2018 [1], destined for different purposes (wine, juice, table grapes, etc.). Grapevine can be considered an important source of bioactive compounds, mainly polyphenols [2]. The extraction procedure is an important step in recovering bioactive compounds from plant matrices. Extraction method effectiveness is evident when different methods are practiced on the same plant matrices by using the same solvent and extraction efficiency shows significant variations [4]. Aglianico is a variety of red grape cultivar cultivated in Southern Italy as Basilicata and Campania. In Basilicata the cultivation of Aglianico vineyards is mainly localized in the Vulture area and the wine awarded the Controlled Designation of Origin (CDO)

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