Relationship Between Antioxidant Capacity, Proanthocyanidin and Anthocyanin Content During Grape Maturation of Touriga Nacional and Tinta Roriz Grape Varieties

To investigate antioxidant capacity in seeds and skins during grape maturation and its relationship withanthocyanin and proanthocyanidin content, two Portuguese red grape varieties, Touriga Nacional and TintaRoriz (Vitis vinifera L.) were studied. Two analytical methods were used for antioxidant capacity analysis:the DPPH and ABTS methods. Proanthocyanidins from seeds and skins were separated into monomers,oligomers and polymers, while 13 individual anthocyanins from the skins were also evaluated by HPLC.For both grape varieties studied, antioxidant capacity from the skins and seeds was characterised duringgrape maturation by a general decrease, mainly in the first weeks after véraison, followed by stabilisationand a slight increase in the values in the last three weeks of ripening. A similar tendency was observedfor the amount of all the different proanthocyanidin fractions quantified. Our results also showed thatseeds are an important source of proanthocyanidins with respect to the grape berry skins. Seeds werealso the grape berry fraction with the highest antioxidant capacity when compared to the antioxidantcapacity content of the skins. For the 13 individual monomeric anthocyanins quantified during grapematuration, evolution was generally characterised by a continuous increase in the values. However, forsome of the individual anthocyanins, the continuous increase was followed by stabilisation or a decreasein the values in the last weeks of ripening. Finally, there was a positive relationship between the differentproanthocyanidin fractions and antioxidant capacity of both grape varieties studied; while a negativerelationship during grape maturation was obtained for individual anthocyanins

Extraction of Some Ellagic Tannins and Ellagic Acid from Oak Wood Chips (Quercus pyrenaica L.) in Model Wine Solutions: Effect of Time, pH, Temperature and Alcoholic Content

The subject of the present work is the study of the influence of pH, temperature, alcoholic content and time on the extraction of some individual ellagic tannins (castalagin, vescalagin, grandinin, roburin D and E) and ellagic acid from oak wood chips (Quercus pyrenaica L.) within model wine solutions. The determination of these compounds by reversed-phase high-performance liquid chromatography (HPLC), after 104 extraction days, enabled us to establish the qualitative and quantitative evolution of each component and the effect of each extraction condition on individual and total ellagic tannins from oak wood chips. Vescalagin and castalagin were the most abundant individual ellagic tannins measured under all extraction conditions. Individual ellagic tannins and ellagic acid increased during the first weeks of extraction, followed by a decrease. Under the extraction conditions examined, temperature was the main factor influencing ellagic tannins and elagic acid evolution. The results suggest that a decrease/degradation of these compounds is less noticeable at low temperatures (12ºC). After 104 extraction days the ellagic tannins content in a model wine solution at 12ºC was higher than the content of ellagic tannins in solutions at 20ºC. On the other hand, the effects of alcoholic content and pH of model wine solutions on the extraction and evolution of the analysed compounds (except for castalagin and vescalagin) seemed to be less important than temperature

Phenolic composition of vine leaves infusions produced from different Portuguese and Spanish Vitis vinifera L. varieties

The main object of the present study was to analyze the phenolic composition of vine leaves infusions prepared from 8 different Portuguese (Fernão Pires, Touriga Franca, Tinta Roriz, Encruzado, Touriga Nacional, Rufete, Baga, and Siria) and Spanish (Pardina, Cayetana, Garnacha, Cigüente, Eva, Tempranillo, Macabeo and Verdelho) Vitis vinifera L. varieties. In general, a wide range of phenolic content were obtained from the vine leaves infusions according to the vine variety used. Thus, for total phenolic content the values ranged from 18 to 37 mg/L for the infusions produced from Portuguese varieties, while for Spanish varieties the values ranged from 14 to 37 mg/L. Vine leaves infusions obtained from Touriga Franca and Pardina varieties showed the highest total phenolic content. As a consequence of phenolic composition, chromatic characteristics (L*, a* and b*) of vine leaves infusions were also analyzed. Finally, it was also detected different individual phenolic compounds, such as, coutaric acid, trans-caftaric acid, quercetin-3-O-glucoside, rutin and 3 different anthocyanins from the different vine leaves infusions. All of the results obtained in this work show that vine leaves infusion may be an interesting alternative source of phenolic compounds for human diet

Role of nutrients on lipid peroxidation and antioxidant defense system

Espécies reativas de oxigênio são formadas durante o metabolismo aeróbico e podem danificar lipídios, proteínas, carboidratos e o DNA. Essas reações, potencialmente deletérias, são controladas por um sistema de antioxidantes enzimáticos e não enzimáticos, que eliminam os próoxidantes e “varrem” os radicais livres. Esta revisão mostra o papel de alguns nutrientes na peroxidação lipídica e no sistema de defesa antioxidante. Enfatizam-se os mecanismos que levam ao dano oxidativo e sua proteção, assim como as implicações na saúde humana.Reactive oxygen species are generated in aerobic metabolism and can damage lipids, proteins, carbohydrates and DNA. These potentially deleterious reactions are controlled by a system of enzymatic and non-enzymatic antioxidants which eliminates prooxidants and scavenge free radicals. This revision focuses the role of particular nutrients in lipid peroxidation and antioxidant defense system. Emphasis was placed on mechanisms for damage and protection, as well implications in human healthy issues