An In-vitro Antioxidant and Antimicrobial Activity of Vitis vinifera Leaf Extract

Abstract

Background: Vitis vinifera (Flame red grape) is known for its hepatoprotective, nephroprotective and cardioprotective activity of ethanolic and aqueous extracts of aerial parts has been reported but, due to presence of polyphenols, glycosides, saponins and alkaloid, the antioxidant and antimicrobial activity yet not to evaluated on salad plant and bacteria, respectively. Aim: This research examined grape (V. vinifera flaming red) leaf ethanolic extract (EE) as a bioactive resource. Methods: Ethanolic extract test, primarily to calculate the overall phenolic content by using the Folin-Ciocalteu technique and gallic acid taking as a reference. Similarly, flavonoid content measured using quercetin as a calibration curve. Antioxidant properties was confirmed by getting positive responses from different methods (DPPH, H2O2, FRAP and Phospho-Molybdenum). Antimicrobial activity tested against gram-positive bacteria (Lactobacillus cereus and Staphylococcus aureus) and gramnegative bacteria (Escherichia coli and Staphylococcus enterica ser. Typhimurium) in a broth microdilution test. The ethanolic extract (EE) are rich in antioxidant-rich phenolic compounds show minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) for every given bacterium on beetroot and spinach leaves. Results: We investigate this extract’s total phenol, total flavonoid, and antioxidant and antibacterial properties. We also identify its main phenolic components, revealing its phytochemical diversity. We found that the EE had 39.29 gGAkg-1 dw of phenol and 96.05 gQE kg-1 dw of flavonoids. The EE scavenges DPPH, H2O2, FRAP, and PM radicals at 142, 168, 275, and 172 g TE kg-1, respectively. We reveal the complex character of this extract by revealing catechins, flavonoids, tannins, malic acid, enzymes, resveratrol, phenolic acids, flavonols, procyanidins, and anthocyanins. Salmonella enterica subsp. enterica serovar Typhimurium, Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus are all inhibited by EE with a MIC range of 16 to 18 gL-1 (E. coli). The extract affects bacterial growth at different stages. The EE reduces spinach and beetroot leaf total bacterial load by 1.159 to 2.456 log drop when used as a sanitizer at 25 gL-1 (1.156–2.858 log reduction). Conclusion: This research work highlights grape leaf EE as a novel and appealing source of bioactive components with its strong antibacterial and antioxidant activities against common foodborne infectious agents. Our research reveals that leaf ethanolic extract could reduce human pathogenic microorganisms in fresh green vegetables, improving food safety.