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02-05-2012 | General practice | Article

Grape, wine extracts could protect against respiratory pathogens


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MedWire News: Phenolic extracts from grapes and wine can inhibit the growth of respiratory pathogenic bacteria that are commonly found in the oral cavity, particularly among people with poor oral hygiene, research shows.

This "warrants further investigations to explore the use of grape and wine preparations in oral hygiene," say the study's authors, reporting their findings in Letters in Applied Microbiology.

Victoria Moreno-Arribas (Autonomous University of Madrid, Spain) and colleagues tested the effects of seven pure phenolic compounds and six commercial grape and wine phenolic extracts on the in vitro growth of seven bacterial strains, all common oral pathogens.

Overall, the bacterial strain Moraxella catarrhalis was the most susceptible to all the phenolic substances tested, and Gram-negative bacteria were typically more susceptible than Gram-positive bacteria.

"This is a promising finding, since many antibiotics are less active against Gram negative than Gram positive bacteria, probably due to a more complex cell wall structure," the authors note.

Of the phenolic compounds tested, 3,4,5 trihydroxybenzoic acid (gallic acid) was the most effective, inhibiting growth of six out of the seven strains. That and ethyl gallate were the strongest inhibitors of bacterial growth for all strains except Streptococcus spp Group F.

Of the phenolic extracts, grape seed extracts (GSEs) were the most active inhibitors of all susceptible strains. The GSE Vitaflavin (20% flavan-3-ols monomers and 80% procyanidins) inhibited growth of Enterococcus faecalis V583, Staphylococcus aureus ATCC 25923, and Streptococcus pneumoniae the most strongly.

Meanwhile a GSE-derived oligomeric-rich fraction (GSE-O; 7% flavan-3-ols monomers and 93% procyanidins) was the most active inhibitor of M. catarrhalis and Pseudomonas aeruginosa PAO1, and a GSE-derived monomeric-rich fraction (GSE-M; 50% flavan-3-ols monomers and 42% procyanidins) was the strongest inhibitor of Streptococcus spp Group F growth.

The authors note that in line with the findings for pure phenolic compounds, these extracts that had the strongest antimicrobial effect had the highest gallic acid content.

Meanwhile GSE-O and GSE-M, together with the wine extract Provinols, had the most extensive antimicrobial effect, being active against all strains except S. agalactiae.

The red grape pomace extract Eminol was active against M. catarrhalis, P. aeruginosa PAO1, and S. pneumoniae only at higher concentrations, while Revidox, a resveratrol-rich extract from grape skins, inhibited growth of M. catarrhalis the most, followed by S. aureus ATCC 25923, S. pneumoniae, P. aeruginosa PAO1, and E. faecalis V583.

"These extracts can serve as potential active components in formulations for oral hygiene," Moreno-Arribas and team conclude.

By Caroline Price

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