Proanthocyanidins: Target Compounds as Antibacterial Agents

Abstract

Grape seeds accumulate in huge quantities as byproduct during wine production and are therefore a cheap source for pharmacologically active agents. However, studies prove poor antibacterial activity, and results of analyses are sometimes contradictory. The aim of this study was, thus, to determine the antibacterial activity of grape seed extracts with special focus on the chromatographic characterization of active fractions. In the course of these investigations, extraction protocols were optimized so that microwave-assisted extraction (MAE) guaranteed highest preconcentration efficiency. Proanthocyanidins, monomeric flavonoid aglycones, as well as some of their glycosides could be identified within yielded extracts via high-performance liquid chromatography-mass spectrometry (HPLC-MS). By that means the coherence number of possible isomers of procyanidins was approximated by a newly developed equation. As far as antibacterial activity determined via screening tests is concerned, the extracts generally have been found to be positively responsive toward 10 different gram-positive and gram-negative bacteria strains. After fractionation of the raw extracts, proanthocyanidins P2, P3, P4 and gallate esters P2G and P3G (P = proanthocyanidin consisting of catechin and epicatechin units, n = oligomerization degree, G = gallate ester) were determined as active antibacterial agents toward 10 different pathogens. Only moderate activity was found for monomeric flavonoid fractions.

Productive Performance, Blood Parameters and Immune Response of Broiler Chickens Supplemented With Grape Seed and Medicago Sativa as Natural Sources of Polyphenols

“…But, the flavonoids are poorly absorbed in the intestines and their concentration in target tissues are very low to perform its role as antioxidant defenses (Surai, 2014). Grape (Vitis Vinifera) seeds are a good source of polyphenolic compounds which have been appeared to have different useful pharmacological impacts, including anti-hyper lipidemic (Moreno et al, 2003), anti-bacterial activities (Mayer et al, 2008) and anti-inflammatory (Terra et al, 2009). Shi et al (2003) reported that the antioxidant potential of GS is 20 and 50 fold higher than Vit.…”

Renoprotective Effect of Grape Seed Extract against Oxidative Stress Induced by Gentamicin and Hypercholesterolemia in Rats

“…Condensed tannins are known as proanthocyanidins, which are the most abundant flavonoids present in GSE. 13 GSE demonstrated the strongest antioxidant effects and free radical scavenging ability 14 as well as being anti-inflammatory, 15 anticancer, 16 antibacterial 17 ; it has platelet aggregation inhibiting and metal chelating properties 18 and vasodilatory, immunostimulating, antiallergic, antiviral activates 19 ; it reduced plasma cholesterol in animals fed a high cholesterol diet and that may reduce risk of atherosclerosis. 20 Recently, GSE has been marketed as dietary supplement and advocated for its multiple beneficial properties.…”

Antibacterial Activity of Pinus pinaster Bark Extract and its Components Against Multidrug-resistant Clinical Isolates of Acinetobacter baumannii

“…In grape seeds, proanthocyanidins were determined as active antibacterial agents toward 10 different pathogenic Gram-positive and Gram-negative bacterial strains. 30 Plant-derived proanthocyanidins may inhibit the growth of pathogenic bacteria by binding strongly to proteins at bacterial cell surfaces. 31 In this research we revealed that PABE at the concentration 200 mg ml -1 showed bactericidal activity against two MDR clinical isolates of A. baumannii belonging to EU clone I and II and antibacterial activity at lower concentrations, in vitro.…”