Antimicrobial Effectiveness of Selected Vranac Wines Against Six Gram-Positive and Six Gram-Negative Bacterial Strains

Purpose: The aim of this study was to assess potential antimicrobial effectiveness of selected red wines from Balkan region, made from autochthonic Vranac V. vinifera L. grape variety. Methods: The antimicrobial activity of Vranac wines against Gram-positive: C. perfringens, B. subtillis, S. aureus, L. inocua, S. Lutea, and M. flavus and Gram-negative: E. coli, P. aeruginosa, S. enteritidis, S. sonnei, K. pneumonia and P. vulgaris bacteria stains were studied using the agar well diffusion and micro-well dilution methods. The concentrations of the wine phenolic compounds: gallic acid, caffeic acid, (+)-catechin, resveratrol, quercetin, quercetin-3-glucoside and malvidin-3-glucoside were determined using HPLC analysis. Results: There was excellent correlation between the contents of gallic acid, caffeic acid, resveratrol, quercetin, quercetin-3-glucoside and malvidine-3-glucoside and the antimicrobial activity of the wines against Gram-positive - C. perfringens and M. flavus (from 0.936 to 0.999) and against Gram-negative bacteria stains - E. coli, P. aeruginosa, S. enteritidis, S. sonnei and P. vulgaris (from 0.904 to 0.999). Furthermore, the content of (+)-catechin has good correlation with the antimicrobial activity of the wines only against L. inocua and P. vulgaris with correlation coefficient of 0.996 and 0.999, respectively. All selected wine phenolic compounds, however, did not show correlation with antimicrobial activity against K. pneumonia strain. Conclusion: The antimicrobial activity of selected Vranac wines indicates that some of the wine's phenolic constituents have the potential to inhibit the growth of certain bacterial strains.