International Journal of Food Properties ISSN: 1094-2912 (Print) 1532-2386 (Online) Journal homepage: https://www.tandfonline.com/loi/ljfp20 Relations Between the Phenolic Composition and Free Radical Scavenging, and Antibacterial Activities of Red Wines from Different Cultivars of Vitis vinifera L. B. Radovanovic, A. Radovanovic & V. Tomic To cite this article: B. Radovanovic, A. Radovanovic & V. Tomic (2012) Relations Between the Phenolic Composition and Free Radical Scavenging, and Antibacterial Activities of Red Wines from Different Cultivars of Vitisvinifera L., International Journal of Food Properties, 15:4, 725-735, DOI: 10.1080/10942912.2010.494923 To link to this article: https://doi.org/10.1080/10942912.2010.494923 Copyright Taylor and Francis Group, LLC Accepted author version posted online: 24 Jun 2011. Published online: 24 Jun 2011. Submit your article to this journal Article views: 217 Citing articles: 3 View citing articles Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalinformation?journalcode=ljfp20
International Journal of Food Properties, 15:725 735, 2012 Copyright Taylor & Francis Group, LLC ISSN: 1094-2912 print / 1532-2386 online DOI: 10.1080/10942912.2010.494923 RELATIONS BETWEEN THE PHENOLIC COMPOSITION AND FREE RADICAL SCAVENGING, AND ANTIBACTERIAL ACTIVITIES OF RED WINES FROM DIFFERENT CULTIVARS OF VITIS VINIFERA L. B. Radovanovic 1, A. Radovanovic 1, and V. Tomic 2 1 Faculty of Science and Mathematics, Department of Chemistry, Nis, Serbia 2 Town Planning Center Nis, Nis, Serbia Polyphenols are widely distributed in the plant kingdom, including the grape (Vitis vinifera L.), and are extracted during winemaking. Because of their potential beneficial health, free radical scavenging and antibacterial activities of some red wines from the Zupa viticulture and winemaking region in Serbia are produced from old autochthonous grape cultivars: Vranac, Kratosija, andprokupac, andfrommerlot, Pinot Noir, andgamay cultivars originated from France. The results showed that the antioxidant activity was highly correlated with the content of total phenolics (r 2 = 0.9737), tartaric esters (r 2 = 0.9980), flavonols (r 2 = 0.8938), and monomeric anthocyanins (r 2 = 0.9239) in selected wines. The antibacterial activity of investigated wines against the pathogenic strain of Staphylococcus aureus significantly correlated with their phenolic constituents. Keywords: Red wines, Phenolics, Tartaric esters, Flavonols, Anthocyanins, Free radical scavenging activity, Antibacterial activity. INTRODUCTION Polyphenols are present in fruit, bark, leaves, and seeds of many plants, where their major function is to provide against microbiological pathogens, insect pests, and larger herbivores. Through the formation of complexes with salivary proteins, these compounds are responsible for the astringency of some fruits and beverages. [1] Phenolic compounds represent one of the most important quality parameters of grapes and wines since they contribute to organoleptic characteristics, such as color, astringency, and bitterness. The phenolic composition in wines is determined by several factors, such as the variety of used cultivars of Vitis vinifera L. and conditions under which they were grown: soil, geographical location, and weather. Usually, the sunlight exposure and temperature are the main factors influencing grape phenolic composition. Winemaking techniques also play a very important role in the chemical composition of the wines: the time of maceration and fermentation in contact with the grape skins and seeds, pressing, maturation, fining and aging conditions. [2] The wine consists of different phenolic compounds, so the antioxidant and the antibacterial activity of wine are connected with a synergy of these Received 7 January 2010; accepted 10 May 2010. Address correspondence to B. Radovanovic, Department of Chemistry, Faculty of Science and Mahematics, Visegradska 33, Nis 18 000, Serbia. E-mail: blaga_radovanovic@yahoo.co.uk 725
726 RADOVANOVIC, RADOVANOVIC, AND TOMIC compounds. Still, it is very important to determine which group of phenolic compounds is most influential in antioxidant and antibacterial properties of wine. Recent studies indicate that consumption of the small amounts of red wine on a regular basis reduce the risk of coronary heart disease and atherosclerosis, and this benefit is ascribed to the antioxidant properties of the polyphenolic compounds. [3 5] In both, in vitro and in vivo research trials, anthocyanins have demonstrated a noticeable ability to reduce cancer cell proliferation and to inhibit tumor formation. [6 8] Finally, the higher the concentration of polyphenols is in wines, the higher will be their antioxidant capacity and antimicrobial activity. [9 15] Serbia is one of the middle-weight wine producers in Europe. Many of the Serbiagrowing districts boast remarkably good ecological conditions for the production of high-quality wines with geographically controlled designations of origin in a large assortment. The Zupa region vineyards are considered to be the best wine-producing regions in Serbia, with a tradition of wine growing that goes back to the pre-roman times. The Zupa wine region has a favorable geographical position and climate conditions, like other renowned vineyards in Europe, such as the French Bordeux. The aim of this study was to determine the free radical scavenging and antibacterial activities of red wines produced from autochthonous and French grape cultivars, produced in Zupa s vineyards and winemaking, and their correlation with content phenolic composition. MATERIALS AND METHODS Chemicals 2,2-Diphenyl-1-picrylhydrazyl free radical, gallic acid, caffeic acid, and quercetin were obtained from Sigma Chemical Co. (St. Louis, MO, USA). The used reagents were of analytical quality. Bacterial Culture Staphylococcus aureus (strain ATCC 28053 gram-positive) micro organism was used for the antibacterial test and was grown on Mueller Hinton dextrose agar. Wine Samples The selected wines with controlled geographical origin from different grape cultivars of vintage grown in Zupa s wine region (Central Serbia) were analyzed. All of them are red wines with a definite geographical origin: Medjas (Zupa Aleksandrovac, 2008); Crno (Zupa Aleksandrovac, 2008); Kratosija (Zupa Aleksandrovac, 2008); Vranac (Zupa Aleksandrovac, 2008); and As (Zupa Aleksandrovac, 2008). Determination of Total Phenolics, Tartaric Esters, and Flavonols Total phenolics, tartaric esters, and flavonols in selected wine samples were determined by spectrophotometrical methods. [16] The dilution wine sample was mixed with ethanol/hcl solvent. Approximately 15 min after the absorbance at 280 nm was used to estimate total phenolics (gallic acid was used as a standard); the absorbance at 320 nm was used to estimate tartaric esters (caffeic acid was used as a standard), and the absorbance at 360 nm was used to estimate flavonols (quercetin was used as a standard).
RED WINES FROM CULTIVARS OF VITIS VINIFERA L. 727 Determination of Monomeric Anthocyanins The total monomeric anthocyanins in wine samples were determined using the phdifferential method described by Guisti and Wrolstad. [17] Anthocyanins have a maximum absorbance at a wavelength of 520 nm at a ph of 1.0. Their colored oxonium form predominates at ph 1.0 and the colorless hemiketal form predominates at ph 4.5. The phdifferential method is based on this reaction, and permits accurate and rapid measurement of the total monomeric anthocyanins: A = (Aλ max A 700 ) ph 1.0 (Aλ max A 700 ) ph 4.5. The result, considered as the monomeric anthocyanin pigment, was calculated as mg of cyanidin-3-glucoside, by using a molar absorptivity (ε) of 26,900 and a molecular weight of 449.20: Monomeric anthocyanins (mgl 1 ) = (A MW 1000)/ε l. Determination of Indices for Anthocyanin Pigment Degradation, Polymeric Color, Browning, and Hue Indices for anthocyanin degradation of the wine can be derived using the phdifferential method described by Guisti and Wrolstad. [17] The absorbance at 420 nm of the bisulfite-treated sample serves as an index for browning. The color density of the control sample and the polymer color of the bisulfite-bleached sample wine were calculated as follows: Color density = [(A 420 nm A 700 nm ) + (Aλ max A 700 nm )]. The value of hue was calculated as follows: Hue = [(A 420 nm A 700 nm )/(Aλ max A 700 nm )], and the ratio between polymerization color and color density was used to determine the percentage of the color that was contributed by polymerized material: Polymeric color (%) = (polymeric color/color density) 100. Free Radical Scavenging Activity The free radical scavenging activity of the wine samples was analyzed by using 2,2-diphenyl-1-picrylhydrazyl (DPPH ) assay. [18 20] Antioxidant assays are based on measurement of the loss of DPPH color by change of absorbance at 517 nm caused by the reaction of DPPH with the tested sample. The reaction was monitored by a UV/VIS spectrophotometer. The diluted wine sample (wine was diluted with water, 1:10 v/v) and fresh 1 10 4 M DPPH methanolic solution were mixed at the indoor temperature. After a 20-min incubation period at room temperature, the absorbance was read against a blank at 517 nm. Scavenging capacity of DPPH in percentage (%) of each wine sample was calculated from the decrease of absorbance according to the equation:
728 RADOVANOVIC, RADOVANOVIC, AND TOMIC Radical scavenging activity (%) = (1 A sample A blank /A control ) 100, where A control is the absorbance of control reaction (methanol with DPPH ), A blank is the absorbance of dilution wine sample, and A sample is the absorbance of the dilution wine sample with DPPH radical. Antibacterial Activity An agar well-diffusion method was used for the determination of the antibacterial activity of the wine samples. [12,15,21,22] The microorganisms mentioned above were incubated at 37 C for 24 h by inoculation into dextrose agar. The number of cells in 1 ml of suspension for inoculation measured by the McFarland nephelometer (Becton, Dickinson and Company, Franklin Lakes, NJ, USA) was 1 107 cfu/ml. A volume of 0.5 ml of this suspension was homogenized with 15 ml of melted dextrose agar and poured into Petri dishes. For screening, sterile 6-mm discs (Hi Media, Mumbai, India) were impregnated with 25 µl of wine sample. After incubation for 24 h in the thermostat at 37 C, inhibition zone diameters, ZI (including disc) were measured and expressed in mm. [22] The presence of the inhibition zone indicates the activity of tested wines against bacteria. Statistical Analysis All of the measurements were carried out in triplicate, and presented as mean ± standard deviations (SD). The direction and magnitude of correlation between variables was quantified by the correlation factor r 2. The P-value less than 0.01 were considered statistically significant. RESULTS AND DISCUSSION Phenolic Composition in Wine Samples Vineyards of the Zupa region focus on the old autochthonous wine varieties: the red Kratosija, Vranac, and Prokupac. These indigenous varieties are often compared to Pinot Noir, Merlot, and Gamay sorts originated from France. Vranac and Kratosija grape varieties are ripe in mid-september, when the skin is dark blue in color. The oldest native Serbian grape variety, Prokupac, has been grown in Zupa for over 500 years. The juice is light red, with a sugar level of 22 24% and acidity of 6 8 g/l. This wine is very suitable for coupling with other red wines and the investigated wines Crno and As were produced coupling Prokupac, Vranac, and Gamay varieties. Then, Medjas wine was produced coupling Merlot, Gamay, and Pinot Noir varieties grown in Zupa s vineyards. The concentrations of total phenolics, tartaric esters, and flavonols of these red wines were presented in Table 1. It was reported that the wines Kratosija and Vranac have an average amount of phenolics as gallic acid equivalent 1,495.17 mg/l, the coupling wines Crno and As have an average amount 1,481.49 mg/l versus 1,533.05 mg/l of coupling wine Medjas from French sorts; also, the wines Kratosija and Vranac have an average amount of tartaric esters 181.86 mg/l as caffeic acid equivalent, the coupling wines Crno and As have an average amount 171.88 mg/l versus 256.65 mg/l of the coupling wine Medjas; and the
Table 1 Content of total phenolics, tartaric esters, flavonols, monomeric anthocyanins, polymeric color, and some relevant parameters in selected red wines a. Wine and vintage Grape varieties Alcohol content (vol%) ph value Total phenolics (mg/l) Tartaric esters (mg/l) Flavonols (mg/l) Monomeric anthocyanins (mg/l) Polymeric color (%) Hue (absorb. units) Medjas, 2008 Merlot, Gamay, P. Noir Kratosija, 2008 11.5 2.85 1533.05 ± 1.14 256.65 ± 1.04 138.17 ± 1.21 42.76 ± 0.78 67.05 ± 0.51 0.9631 Kratošija 11.0 2.80 1497.70 ± 2.05 194.66 ± 1.55 126.39 ± 1.42 41.57 ± 0.53 67.39 ± 0.43 0.8514 Vranac, 2008 Vranac 11.0 2.78 1492.65 ± 2.03 173.07± 1.53 109.34± 0.46 41.24 ± 0.85 66.43± 1.03 0.9352 Crno, 2008 Prokupac, 11.2 2.87 1482.87 ± 2.20 172.46 ± 2.04 109.05 ± 0.71 40.70 ± 0.52 67.60 ± 0.81 0.9552 Vranac, Gamay As, 2008 Prokupac, 11.0 2.86 1480.10 ± 2.06 171.30 ± 1.81 108.62 ± 1.04 40.50 ± 0.44 67.88 ± 0.42 0.9524 Vranac, Gamay a Data are the means ± standard deviation values (n = 3). 729
730 RADOVANOVIC, RADOVANOVIC, AND TOMIC wines Kratosija and Vranac have an average amount of flavonols 117.87 mg/las quercetin equivalent, the coupling wines Crno and As have an average amount 108.84 mg/l versus 138.17 mg/l of the coupling wine Medjas produced from Merlot, Gamay, and Pinot Noir. The differences between obtained values were influenced by the actual contents of phenolic compounds of the different variety grape. So, analyzed red wines from autochthonous varieties grapes contain lower values of total phenolics, tartaric esters, and flavonols compared to red wines from French varieties, but there are no significant differences among these red wines. In addition, the anthocyanin content as an important quality parameter of red wines was investigated. Anthocyanin compounds influence final color of the resulting wines. [7] Anthocyanins have several different ionic forms in wine that change based on wine ph. At typical wine ph, somewhere between 10 to 15% of the monomeric anthocyanins present are pigments. Anthocyanin pigment undergoes a reversible structural transformation with a change in ph manifested by strikingly different absorbance spectra. At a ph 1.0, anthocyanins are in red colored oxonium form (flavilium cation); however, at ph 4.5, a proton is lost from the anthocyanin resulting in a carbinol pseudo base structure (hemiketal), which is colorless. The concentration of monomeric anthocyanins determined by the ph-differential method is presented in Table 1. The results show that the range of monomeric anthocyanins in investigated wines was 40.50 42.76 mg/l (mean 41.35 mg/l, SD = 0.79, n = 5) as cyanidin-3-glucoside equivalent. The wines Kratosija and Vranac have an average amount 41.41 mg/l, the coupling wines Crno and As have an average amount 40.60 mg/l versus 42.76 mg/l of the coupling wine Medjas. The concentration of monomeric anthocyanins is essential for good color of the wine produced by different grape varieties. It was observed that the hue of investigated wine samples was from 0.8512 to 0.9626 absorbance units. However, monomeric anthocyanins are subject to hydrolysis, oxidation, and polymerization in wine. Wine characteristics, such as ph, the amount of SO 2, and acetaldehyde, influence these processes and anthocyanin interactions with other phenolic compounds. Anthocyanins can become associated with polymeric molecules in wine through a complex set of reactions. Polymeric color, determined by the ph-differential method, ranged between 67.05 and 67.88% (average amount 67.07%, SD = 0.62, n = 5), in correlation with grape varieties of these young wines. The Correlation between the Phenolic Constituents and Free Radical Scavenging and Antibacterial Activities of the Wine Samples It is clear that the wine is a complex mixture of polyphenols and free radical scavenging capacity can be expressed as the amount of wine needed to quench a certain amount of DPPH free radicals. [23 26] The decrease in the absorbance at 517 nm is taken as a measure of the extent of radical scavenging. All wine samples show a higher DPPH radical scavenging activity after incubation with a free radical solution. The total content of phenolics, tartaric esters, flavonols, and monomeric anthocyanins in investigated wines contribute to its increased antioxidant activity. All investigated wines show very similar antioxidant behavior in a range from 59.55 to 63.98% scavenging ability of DPPH radical (average amount 60.75%, SD = 3.50, n = 5). On the basis of the studies done by other researchers in which the anthocyanins are absorbed by the body and interfered with metabolism of normal and cancerous cells by interacting with the production of metabolites and with cellular receptors, it is suggested that anthocyanins could be bioactive compounds in vivo. [6,9,19,27] In this study, the
RED WINES FROM CULTIVARS OF VITIS VINIFERA L. 731 Table 2 Correlation coefficients (r 2 ) between phenolic constituents and free radical scavenging and antibacterial activities in selected red wines. Total phenols Tartaric esters Flavonols Monomeric anthocyanins Radical scavenging activity 0.9737 0.9980 0.8938 0.9239 Antibacterial activity against S. aureus 0.7617 0.5576 0.7929 0.8550 strain antibacterial activity of the selected wine samples against Staphylococcus aureus strain is analyzed. The diameter of inhibition zone (mm) obtained from the wine samples, also reported in Table 2, show that antibacterial activity was in a range from 17 to 18.5 mm (average amount 17.8 mm, SD = 0.33, n = 5). The different activity of investigated wines against the pathogenic bacteria tested, gave a hypothetical relationship between phenolic compounds of the wines and their antibacterial effect. Since structural features of phenolic compounds are reportedly responsible for antioxidant and antibacterial activity, measurements of total phenolics on wines may be related to their physiological activities. The phenolic content and DPPH radical scavenging activity are very closely correlated (r 2 = 0.9737, SD = 0.35, P < 0.001, n = 5) for the all analyzed wines and the significant linear correlation (r 2 = 0.7617, SD = 0.32, P < 0.005, n = 5) also, was confirmed between total phenolics and antibacterial activity against S. aureus (Fig. 1). The correlation coefficient between the concentration of tartaric esters and the DPPH scavenging ability was very good (r 2 = 0.9980, SD = 0.10, P < 0.001, n = 5), but the correlation coefficient between tartaric esters and antibacterial activity against S. aureus strain was 0.5576 (SD = 0.41, P = 0.10, n = 5) (Fig. 2). The correlation between the concentration of flavonols and the antioxidant and antibacterial activities against S. aureus strain, also was confirmed (Fig. 3). The correlation coefficient between the concentration of flavonols and the DPPH scavenging ability was good (r 2 = 0.8938, SD = 0.70, P < 0.01, n = 5), and the correlation coefficient between flavonols and antibacterial activity against S. aureus strain was 0.6286 (SD = 0.79, P = 0.10, n = 5). The correlation between the concentration of monomeric anthocyanins and the antioxidant and antibacterial activities against S. aureus strain was confirmed (Fig. 4). The correlation coefficient between the concentration of monomeric anthocyanins and the DPPH scavenging ability was very good (r 2 = 0.9239, SD = 0.59, P < 0.01, n = 5), and the antibacterial activity against S. aureus strain also was good (r 2 = 0.8550, SD = 0.25, P < 0.02, n = 5). The results of this study showed that selected red wines have potent antioxidant and antibacterial properties in vitro as estimated by DPPH radical scavenging assay and an antibacterial test against the S. aureus strain. The correlations were very good between antioxidant activity and total phenolics, tartaric esters, flavonols, and monomeric anthocyanins of tested wines. The significant linear correlation between wine phenolic compounds and antibacterial activity against the S. aureus strain of wines was confirmed also (Table 2). The structure activity relationships of the antimicrobial activity of phenolic compounds are often contradictory. [28] As wine is complex of phenolic compounds, the physiological activity of selected wines is not a property of a single phenolic compound. It is important to determine which group of phenolic compounds is the most significant in determining antioxidant and antimicrobial potency of wine. Our results suggest that the
732 RADOVANOVIC, RADOVANOVIC, AND TOMIC Figure 1 Relationship between radical scavenging ( ) and antibacterial ( ) activity against S. aureus strain and total phenolic content of selected wine samples. Figure 2 Relationship between radical scavenging ( ) and antibacterial ( ) activity against S. aureus strain and tartaric esters of selected wine samples.
RED WINES FROM CULTIVARS OF VITIS VINIFERA L. 733 Figure 3 Relationship between radical scavenging ( ) and antibacterial ( ) activity against S. aureus strain and flavonols of selected wine samples. Figure 4 Relationship between radical scavenging ( ) and antibacterial ( ) activity against S. aureus strain and monomeric anthocyanins of selected wine samples.
734 RADOVANOVIC, RADOVANOVIC, AND TOMIC amounts of monomeric anthocyanins are very important for understanding the antioxidant and antibacterial potency of tested wines. CONCLUSIONS According to the results obtained in this study, the free radical scavenging ability of investigated wines was strongly correlated with phenolic composition. A relatively good amount of phenolic constituents, and significant antioxidant and antibacterial activities in red wines produced from different vine varieties from the Zupa Serbian viticulture and winemaking region, were observed. However, differences in the free radical scavenging and antibacterial activities between wine from Merlot, Gamay, and Pinot Noir grape cultivars and wines from Kratosija and Vranac indigenous varieties were not confirmed. On the basis of the studies done by other researchers, in which the anthocyanins were absorbed by the body and interfered with metabolism of normal and cancerous cells by interacting with the production of metabolites and with cellular receptors, it is suggested that anthocyanins could be bioactive compounds in vivo. Our results showed a significant correlation between the amounts of anthocyanins in investigated wines and its free radical scavenging and antibacterial activities against S. aureus strain. ACKNOWLEDGMENT The research was supported by the Europen Union, FP7 REGPOT 2007-3-01, KBBE: Food, Agriculture, and Biotechnology, Project Chromlab-Antioxidant, No. 204756. REFERENCES 1. Rasmussen, S.E.; Fredriksen, H.; Krogholm, K.S.; Poulsen, L. Dietary proanthocyanidins: Occurrence, dietary intake, bioavailability, and protection against cardiovascular disease. Molecular Nutrition and Food Research 2005, 49, 159 174. 2. Ribéreau-Gayon, P.; Dubourdieu, D.; Doncche, B.; Lonvaud, A. Red winemaking. In: Handbook of Enology, Vol. 1; John Wiley and Sons: New York, 1998; 295 358. 3. Gey, K.F. The antioxidant hypothesis of cardiovascular disease: Epidemiology and mechanisms. Biochemical Society Transaction 1990, 18, 1041 1045. 4. Jang, M.; Cai, L.; Udeani, G.O.; Slowing, K.V.; Thomas, C.F.; Beecher, C.W.W.; Fong, H.H.S.; Farnsworth, N.R.; Douglas Kinhorn, A.; Mehta, R.G.; Moon, R.C.; Pezzuto, J.M. Cancer chemopreventive activity of resveratrol, a natural product derived from grapes. Science 1997, 257, 218 220. 5. Renaud, S.; de Lorgeril, M. Wine, alcohol, platelets and the French paradox for coronary heart disease. Lancet 1992, 339, 1523 1526. 6. Lila, M.A. Anthocyanins and human s health: In vitro investigative approach. Journal of Biomedicine and Biotechnology 2004, 5, 306 313. 7. Hou, D.X. Potential mechanisms of cancer chemoprevention by anthocyanins. Current Molecular Medicine 2003, 3 (2), 149 159. 8. Tsuda, T.; Horio, F.; Osawa, T. The role of anthocyanins as an antioxidant under oxidative stress in rats. Biofactors 2000, 13, 133 139. 9. Daglia, M.; Papeti, A.; Grisoli, P.; Aceti, C.; Dacarro, C.; Gazzani, G. Antibacterial activity of red and white wine against oral Streptococci. Journal of Agricultural Food Chemistry. 2007, 55, 5038 5042.
RED WINES FROM CULTIVARS OF VITIS VINIFERA L. 735 10. De Beer, D.; Joubert, E.; Gelderblom, W.C.A.; Manley, M. Antioxidant activity of South African red and white cultivar wines: Free radical scavenging. Journal of Agricultural Food Chemistry 2003, 51, 902 909. 11. De Beer, D.; Joubert, E.; Gelderblom, W.C.A.; Manley, M. Antioxidant activity of South African red and white cultivar wines and selected phenolic compounds: In vitro inhibition of microsomal lipid peroxidation. Food Chemistry 2005, 89, 569 577. 12. Papadopoulou, C.; Soulti, K.; Roussis, I.G. Potential antimicrobial activity of red and white wine phenolic extracts against strains of S. aureus, E.coli and C.albicans. Food Technolology and Biotechnology 2005, 43 (1), 41 46. 13. Sugita-Konishi, Y.; Hara-Kudo, Y.; Iwamoto, T.; Kondo, K. Wine has activity against enteropathogenic bacteria in vitro but not in vivo. Bioscience, Biotechnology, And Biochemistry 2001, 65, 954 957. 14. Weisse, M.E.; Eberly, B.; Person, D.A. Wine as a digestive aid: Comparative antimicrobial effects of bismuth salicylate and red and white wine. Bioscience, Biotechnology, and Biochemistry 1995, 311, 1657 1660. 15. Radovanovic, A.; Radovanovic, B.; Jovancicevic, B. Free radical scavenging and antibacterial activities of southern Serbian red wines. Food Chemistry 2009, 117, 326 321. 16. Mazza, G.; Fukumoto, P.; Delaquis, B.; Girard, E.B. Anthocyanins, phenolics, and color of Cabernet Franc, Merlot, and Pinot Noir wines from British Columbia. Journal of Agricultural Food Chemistry 1999, 47, 4009 4017. 17. Guisti, M.; Wrolstad, R. Characterization and measurement of anthocyanins by UV-visible spectroscopy. Current Protocols in Food Analytical Chemistry; John Wiley and Sons: New York, 2003. 18. Fuhrman, B.; Volkova, N.; Suraski, A.; Aviram, M. White wine with red wine-like properties: Increased extraction of grape skin polyphenols improves the antioxidant capacity of the derived white wine. Journal of Agricultural Food Chemistry 2001, 46, 3164 4168. 19. Sanchez-Moreno, J.; Larrauri, J.A.; Saura-Calixto, F. Free radical scavenging capacity of selected red, rose and white wines. Journal of Agricultural Food Chemistry 1999, 79, 1301 1304. 20. Villano, D.; Fernandez-Pachon, M.S.; Troncoso, A.M.; Garcia-Parrilla, M.C. Influence of enological practices on the antioxidant activity of wines. Food Chemistry 2006, 95, 394 404. 21. Bauer, A.W.; Kirby, W.M.; Sherris, J.C.; Turck, M. Antibiotic susceptibility testing by a standardized single disk method. American Journal of Clinical Pathology 1996, 45, 493 496. 22. NCCL (National Committee for Clinical Laboratory Standard). Performance Standards for Antimicrobial Susceptibility Testing, 9th International Supplement; National Committee for Clinical Laboratory Standard: Wayne, PA, 1999; M100 S9. 23. Arnous, A.; Markis, D.P.; Kefals, P. Correlation of pigment of flavonol content with antioxidant properties in selected aged regional wines from Greece. Journal of Food Composition and Analysis 2002, 15, 655 665. 24. Landroult, N.; Poucheret, P.; Ravel, P.; Gasc, F.; Cros, G. Antioxidant capacities and phenolics levels of French wines from different varieties and vintages. Journal of Agricultural Food Chemistry 2001, 49, 332 328. 25. Minussi, R.C.; Rossi, M.; Bologna, J.; Cordi, J.; Rotilio, D.; Pastore, M.; Duran, N. Phenolic compounds and total antioxidant potential of commercial wines. Food Chemistry 2003, 82, 409 416. 26. Munoz-Espada, A.C.; Wood, K.V.; Bordelon, B.; Watkins, B.A. Anthocyanin quantification and radical scavenging capacity of Concord, Norton and Marechal Foch grapes and wines. Journal of Agricultural Food Chemistry 2004, 52, 6779 6786. 27. Meiers, S.; Kmeny, D.; Weyand, U.; Gastpar, R.; von Angere, E.; Marko, D. The anthocyanidins cyanidin and delphinidin are potent inhibitors of the epidermal growth-factor receptor. Journal of Agricultural Food Chemistry 2001, 49, 958 962. 28. Cowan, M. Plant products as antimicrobial agents. Clinical Microbiology Reviews 1999, 12, 564 582.