From Field to Health:  A Simple Way To Increase the Nutraceutical Content of Grape As Shown by NO-Dependent Vascular Relaxation

Abstract

Polyphenolic grapevine components involved in plant resistance against pathogens possess various pharmacological properties that include nitric oxide (NO)-dependent vasodilation and anti-inflammatory and free radical scavenging activities, which may explain the protective effect of moderate red wine consumption against cardiovascular disease. The aim of this work was (a) to verify the possibility that preharvest treatments of grapevine with a plant activator, benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH), could lead to an enriched nutraceutical potential of wine and (b) to characterize the profile of metabolites responsible for pharmacological activity. Plant spraying at the end of veraison, with a water suspension of BTH (0.3 mM), led to increased whole anthocyanin content as confirmed by HPLC comparative analysis. Extracts from berry skins of BTH-treated grapevines caused NO-dependent vasorelaxation, with a concentration-response curve that was significantly shifted to the left of the control non-BTH-treated curve. Moreover, 1:1000 dilutions of berry extracts from BTH-treated plants significantly increased basal production of guanosine 3',5'-cyclic monophosphate (cGMP) in human vascular endothelial cells when compared to the corresponding extracts of untreated plants. These results show that BTH treatment increases anthocyanin content of grape extracts, as well as their ability to induce NO-mediated vasoprotection. No increase of anthocyanin content was observed in the wine extracts from BTH-treated vines. It is concluded that BTH treatment could be exploited to increase the nutraceutical potential of grapes.

Elicitors: A Tool for Improving Fruit Phenolic Content

“…Field treatments of grapevine with BTH improve resistance to B. cinerea and enhance resveratrol and anthocyanin biosynthesis [68]. Similar studies also found an increase in total polyphenols in berry skin, particularly, the proanthocyanidin fraction [44,69], and in the anthocyanin, flavonol, and proanthocyanidin content of grapes and the color of the corresponding wines [70]. Postharvest treatment with BTH resulted in an enhancement of the phenolic and anthocyanin contents of strawberries [71].…”

Benzothiadiazole Induces the Accumulation of Phenolics and Improves Resistance to Powdery Mildew in Strawberries

“…In grapes, the higher phenolic content was linked to the enhanced resistance against Botrytis cinerea in the fruits (10). Preharvest BTH treatment has also given protection against postharvest gray mold in strawberries (15), suggesting that BTH causes long-term changes in secondary metabolism, which might not only improve resistance to pathogens but also influence the nutritional value and bioactive properties of the crop (22). Concentration of Salicylic Acid.…”

“…Furthermore, few studies have been conducted on the changes of secondary metabolites in edible plant parts in any crop species after BTH treatment, although it might have an influence on the nutritional quality of the crop (21,22).…”

A Standard Addition Method to Assay the Concentration of Biologically Interesting Polyphenols in Grape Berries by Reversed-Phase HPLC

“…Recent reports in the literature have linked the moderate consumption of products such as wine and grape juices with a reduced incidence of coronary heart disease [2], prevention of Among the various phenolic antioxidants present in grapes, (+)-catechin, (−)-epicatechin, resveratrol, quercetin and its glucosides (Figure1) are the most potent, since they have been found to protect the human LDL against oxidation more efficiently than α-tocopherol on a molar basis [12]. They are also active as potent promoters of vascular relaxation through the generation of nitric oxide by the endothelium [13]. In addition, trans-resveratrol and quercetin are potent inhibitors of platelet aggregation in rats [14] and modulate eicosanoid synthesis toward a pattern likely to be protective against CHD [15].…”

“…Thus, there are many reports in the literature concerning the resveratrol isomers and glycosides [19] content of various wine samples and some research, including our own [20], on the concentration of other biologically interesting polyphenolic antioxidants, such as flavonoids (eg. (+)-catechin, (-)-epicatechin [13,21]. On the other hand, investigations on the concentration of polyphenolic antioxidants in grapes concern mostly the assay of grape berries during different stages of their maturation or when they have been injured by disease or UV irradiation [22,23].…”