engleski

Analysis of biologically active polyphenols in wines from Croatia

ANALYSIS OF BIOLOGICALLY ACTIVE POLYPHENOLS IN WINES FROM CROATIA V. Rastija and M. Medić- Šarić Introduction Polyphenols are secondary plant metabolites that attract great interest due to their biological activities, such as antioxidant activity, anti-inflammatory, antimicrobial and antifungal action. There is evidence that some of them have positive effect against a large variety of degenerative processes, such as cancer, atherosclerosis, cardiovascular disorders, age-related macular degeneration and cognitive decline in aging. Wines contain large amount of polyphenols such as phenolic acids, flavones, flavonols, catechins, anthocyanins, procyanidins and resveratrol. Considering the importance of biologically active polyphenols in wine, it is necessary to develop an accurate and rapid method for their analysis. Materials and Method Twelve commercial wines, vintage 2002, from three different wine-growing Sub-regions of Croatia were analyzed. Total polyphenols were analyzed according to the Folin– Ciocalteu method. Samples for chromatographic analysis were prepared by extraction of wines with diethyl ether at pH 2. A reversed-phase high performance liquid chromatographic (HPLC) method that uses gradient elution and diode array detection (DAD) to determine 7 phenolic acid and eight flavonoids in wine extracts was developed. The chromatographic separation of these polyphenols was performed in a single run with flow rate at 1 ml/min and UV-visible spectra were recorded between 250 -500 nm and compared with those of standards. Wavelengths used for quantification were 280 nm and 360 nm. Results Analysis of total polyphenols by Folin– Ciocalteu method implied that wines produced in Mediterranean part of Croatia have a highest polyphenolic content. White wines contain significantly lower amounts of total polyphenols (400.8 mg/L) compared with red wines (1665.131 mg/L). Applied HPLC method allows the separation of 19 polyphenols with antioxidant properties from wine extracts in a single run. The most abundant polyphenol is gallic acid (0.7 – 26.9 mg/L). Biologically most active compounds, catechin and trans- resveratrol were present in each of analyzed wine. Highest concentrations of those compounds, together with one of the most potent antioxidant - quercetin, were determined in wines from Dalmatia. Since the vintage of the examined wines was identical, the observed quantitative differences are related to the grape variety, geographical origin, growing and winemaking procedures. Conclusion The present study, which utilized new HPLC method for simultaneous determination of fifteen polyphenols and analysis of total polyphenols, demonstrates that the wines made from Croatia contain a significant amount of biologically active polyphenols and certainly, moderate and regular consumption of those wines (in particular red wine) can reduce risk of some diseases. However, wines made in Dalmatia contain a highest level of polyphenols as a result of dry mediterranean clime with high cluster sun exposure, so those wines could have highest positive effects on human health.

HPLC ; polyphenols ; wine

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