Melatonin, melatonin isomers and stilbenes in Italian traditional grape products and their antiradical capacity

Abstract

Although polyphenols represent the paradigm of the health-promoting effects ascribed to grape products, recently, attention has been paid to dietary melatonin, significantly present in Mediterranean foods. In this work, we measured melatonin, its isomers, stilbenes (trans- and cis-resveratrol and their glucosides, piceids) and total polyphenols in some different grape products (red, white and dessert wines, grape juices and Modena balsamic vinegars) of distinct Italian areas. We also evaluated their antiradical activity by DPPH(·) and ABTS(·+) assays. For indoleamine analysis, the separation was carried out on a 1.7-μm C18 BEH column and the detection performed by means of mass spectrometry with electrospray ionization in positive ion mode with multiple reaction monitoring. The confirmation of the peak identity was accomplished by injection into the high-resolution system (Orbitrap) using accurate mass measurements (error below 1.0 ppm). Mass spectrometry analyses revealed, for the first time, the presence of melatonin in dessert wines and balsamic vinegars, as well as the occurrence of three different melatonin isomers in grape products.

Melatonin, an underestimated natural substance with great potential for agricultural application

“…This process is described as the free radical scavenging cascade, which makes MEL highly effective, even at low concentrations, in protecting organisms from oxidative stress (Galano et al 2013). Evidence supports the conclusion that plants and plant products contain isomers of this indoleamine which may be also ROS scavengers (Tan et al 2012b;Vitalini et al 2013). MEL reduces oxidative damage of important molecules and its antioxidant activity may manifest itself in several ways: (i) direct free radical scavenging; (ii) elevating the antioxidant enzyme activity; (iii) protecting antioxidant enzymes from oxidative damage; (iv) increasing the efficiency of the mitochondrial transport chain and (v) reducing the generation of free radicals (Tan et al 2010).…”

Involvement of melatonin applied to Vigna radiata L. seeds in plant response to chilling stress

“…It is likely that the high antioxidant efficacy in this variant was the result of the joint action of phenolics and MEL metabolites. Vitalini et al [55] considered the possibility that the documented beneficial health properties of grape/wine are not only due to the presence of phenolics, but also MEL, its isomers and hundreds of other phytochemicals present in these foods.…”

Cardioprotective effects of moderate red wine consumption: Polyphenols vs. ethanol

“…These findings can be, at least in part, explained by current evidences related to wine chemicals, thus we suppose that beneficial effects of wine on reducing inflammatory and vascular biomarkers could be ascribed not only to phenolic content, but also to the presence of many other phytochemicals, such as melatonin and phytosterols, as recently reported (Ruggiero et al, 2013;Vitalini et al, 2013). Melatonin protects against atherosclerosis-related cardiovascular diseases, resulting from direct free radical-scavenging activity, indirect antioxidant properties and anti-inflammatory activity .…”