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Ilker Durak, Aslihan Avci, Murat Kaçmaz, Serap Büyükkoçak, M. Y.
Burak Çimen, Serenay Elgün and H. Serdar Öztürk
Ankara University
Medical Faculty, Department of Biochemistry, Ankara, Turkey
[Current Medical Research and Opinion 15(4):316-320, 1999]
Red wine, white wine and grape juice exert strong antioxidant activity in similar degrees and all produce significant effects on serum AOP and NSSA values. However, ethyl alcohol does not have either AOP or NSSA, nor does it have an effect on serum AOP or NSSA values. AOP values (nmol/ml h) of red wine, white wine and grape juice were 20.8 ± 4.2, 23.2 ± 4.0 and 24.6 ± 4.8, respectively. NSSA values (U/ml) of red wine, white wine and grape juice were 30.4 ± 6.8, 26.8 ± 5.6 and 32.6 ± 5.8, respectively. There were no statistically meaningful differences between AOP and NSSA values of the groups (p > 0.05 for all).
Results suggest that red wine, white wine and grape juice all have high antioxidant potential to protect cellular structures against peroxidation reactions owing to their rich phenolic contents.
The aim of the present study was to compare the antioxidant potential of red wine, white wine, grape juice and ethyl alcohol.
The AOP value was measured as described below, which is a modification of the method by Durak et al. (1998)[5]. In the reaction medium enriched with fish oil (see Table 1), samples were exposed to the superoxide radical (O2) produced by the xanthine/xanthine oxidase system for one hour, and then malondialdehyde (MDA) levels were measured as previously described[19]. By using this reaction system, it is possible to obtain more precise information on the antioxidant potentials of the samples. To achieve this, MDA levels were measured in both blanks and the samples. The antioxidant potential value was assessed from the differences between MDA levels in the blanks and the samples, which was proportional to the AOP values of the samples. Results were expressed as nmol ml-1 h-1. The analysis scheme is given in Table 1.
NSSA values of the samples were established as described by Durak et al. (1998)[4]. In these superoxide dismutase (SOD) enzyme activity measurement methods, the total (enzymatic plus non-enzymatic) superoxide radical scavenger activity, as opposed to the SOD activity, was measured. In the method used here, the activity assay was carried out after protein precipitation by TCA solution (20% w/v) to obtain the non-enzymatic superoxide scavenger activity (NSSA)[4].
Statistical analyses were made by ANOVA.
The effects of red wine, white wine and grape juice on serum AOP and NSSA values were quite near and there were no statistically meaningful differences between groups in this regard.
The results of this study demonstrate that red wine, white wine and grape juice all have comparable antioxidant activities but ethyl alcohol displays no activity in this respect. Indeed, it has been found that black grapes, from which red wine is manufactured, is also rich in phenolic antioxidants[1]. In a study, it has been established that black grape ingestion enhances blood antioxidant activity after one week of use[3]. However, in a recent study it has been argued that although red wine and black grapes both have in vitro antioxidant activities, only red wine ingestion enhances blood antioxidant defence potential in vivo[15]. They suppose that flavonoids of red wine are absorbed from the intestine into the bloodstream more efficiently than those of grape juice[15]. This is in contrast to a previous study that suggested that red grape extract has beneficial effects in vivo on blood antioxidant activity[3]. In our opinion, Miyagi et al. failed to measure the effect of black grape ingestion on blood AOP because of the fact that blood samples were obtained after only two hours of ingestion[15]. If additional blood samples had been obtained afterwards, they would have probably found increased blood AOP values as established in our previous study[6]. It is possible that the antioxidant effects of red wine on the blood antioxidant system occurs earlier than that of black grapes because the release of polyphenols from the grapes and absorption through the intestinal cells takes longer than it does for red wine. Our results agree well with the results of a previous study that reported that red grape ingestion results in increased serum antioxidant activity[3]. In relation to white wine, however, there are different results. In one study it was reported that white wine had no antioxidant activity[10] since phenolic antioxidants are removed during its manufacturing process[14]. In another, it was found that white wine also exerts antioxidant activity although its activity is approximately half that of red wine[20]. It is possible that whether or not white wine has any antioxidant activity is related to its manufacturing process, in which somewhat different techniques may be applied. We think that if white wine were to be manufactured so that it preserved its phenolic antioxidants, it could exert antioxidant activity. As seen from the Table 2, white wine used in the present study (Villa Doluca Brand, 1998) exerts both in vivo and in vitro antioxidant activities comparable to red wine, indicating that the manufacturing processes applied do not remove its phenolic constituents. In relation to the antioxidant activity of ethyl alcohol, our results are in close agreement with previous ones, suggesting that the antioxidant activities of wines do not result from their alcohol contents, i.e. alcohol has neither in vivo nor in vitro antioxidant activities[7,14].
In the light of these results, we think that not only red wine but also white wine and grape juice can have similar effects in vivo on the blood antioxidant system, and thus can play a part in lowering the mortality rates for CAD risk factors in some populations such as those in France, whose population consume all these beverages in larger amounts relatively to the populations of many other countries.
Sample (ml) Blank (ml) Sample 0.200 - Fish Oil* 0.010 0.010 Xanthine (10 mM) 0.100 0.100 Xanthine oxidase** 0.100 0.100 Incubation for one hour at room temperature (25°C) Sample - 0.200 MDA measurement
Abbreviations: *Prepared by dissolving 1 ml fish oil (with total lipid content of 0.706 g/ml) in 2 ml acetone.
**Prepared by diluting xanthine oxidase (XO) (Sigma X-4500, 2.9 mg protein/ml, 1.6 U/mg protein) 40-fold in (NH4)2SO4 solution of 2 M. Final amount of XO in the assay medium was 0.012 U.
Sample AOP (nmol ml-1 h-1) NSSA (U/ml) Effects on serumAOP* Effects on serum NSSA* 1. Red wine (n = 5) 20.8 ± 4.2 30.4 ± 6.8 11.2 ± 2.4 12.8 ± 3.2 2. White wine (n = 5) 23.2 ± 4.0 26.8 ± 5.6 13.4 ± 2.8 9.6 ± 2.1 3. Grape juice (n = 5) 24.6 ± 4.8 32.6 ± 5.8 15.2 ± 3.2 13.2 ± 3.0 4. Alcohol (n = 5) ** *** n.c. n.c. ANOVA**** F = 0.98; p < 0.5 F = 1.13; p < 0.5 F = 2.52; p < 0.25 F = 2.47; p < 0.25
*1 ml serum + 0.3 ml sample; **no activity in AOP; ***no activity in NSSA.
n.c. = no contribution.
****Red wine, white wine and grape juice groups were compared.
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