Chemical Composition and Biological Activities of Seeds from Four Vitis vinifera Tunisian Varieties

Abstract

Thousands of polyphenolic compounds have been identified in various plants. Recently, a number of studies showed that beneficial effects of grapes are related to the presence of polyphenols, with multiple biological activities. The aim of this study was to compare the polyphenol profiles as well as biological activities of the seeds of four Tunisia cultivated grape cultivars, syrat, merlot, cabernet sauvignon and carignan. The total phenolic content of seed extracts varied between varieties and seemed to be correlated to the scavenging activity. Preliminary antibacterial results showed a good growth inhibitory activity of syrat cultivar against Staphylococcus epidermidis. To our knowledge, this is the first of such study being performed on this bacterium, known as a leading cause of Tunisian hospital-acquired infections. Gas Chromatography Mass Spectrometry analysis identified 20 polyphenol components, flavonoids being the most abundant in all extracts, followed by phenolic acids, resveratrol, tyrosol, and syringaldehyde. We also noticed a deficiency of three phenolic acid compounds (salicylic acid methyl ester, ferulic acid, Sinapic acid) as well as a flavonoid one (myricetin) in merlot cultivar, which could be responsible for its low antioxidant activity. These results will help in the selective exploitation of the seeds obtained from winemaking wastes, as well as in further pharmacological and/or in vivo investigations.