Atividade biológica de diferentes sucos de uva e seus principais constituintes

Abstract

Although the beneficial effects of the moderate intake of wine are well known, the antioxidant capacity of grape juices is still little reported. Grape juice is a food which has important amount of polyphenols, thus, it can be included among the foods with high antioxidant potential. Studies with grape juice are very relevant since this beverage is widely consumed and presents economical importance in our region. Nowadays there are several types of grape juices in the market; white, purple and rose, organic or conventional. Grape juice has many nutrients and bioactive compounds with antioxidant, antimutagenic, anticarcinogenic and antiteratogenic activities. Polyphenols are components which play important roles in grape juice, since their presence contributes to the coloring, acidity and other characteristics of the juice. Several beneficial activities to human health are attributed to polyphenols. However, studies related to juice beneficial activity, a complex substance, were scarce. This study aimed to assess: 1) antioxidant and antimutagenic activities of different grape juices and the metals influence in these activities; 2) antioxidant activity of rose grape juice; 3) neuroprotective and hepatoprotective activities of grape juice in young Wistar rats; 4) serum antioxidant activity of grape juice in young Wistar rats; 5) neuroprotective, hepatoprotective and antigenotoxic activities in old Wistar rats; and 6) protective activity of resveratrol and catechin against distinct stressor agents in different strains of S. cerevisiae yeast. Some metals like Manganese and Sulfur showed positive and negative correlations with these activities, respectively. Moreover, mineral content varied between white and purple juices. However, Potassium was the most prevalent mineral (in both juices). Thus, the correlations reported could also distinguish white from purple juices. Wistar rats (male) were used as in vivo models. They were treated by gavage twice a day, for 30 days, receiving in total a volume of grape juice corresponding to their weight. Rats were divided into three groups: control (saline), organic and conventional grape juice. On the 30th day, half of each group received a single dose of the stressor agent CCl4 equivalent to their weight. After six hours, the animals were sacrificed. Experiments with the moldel yeast S. cerevisiae demonstrated that the grape juices studied present important antioxidant and antimutagenic activities. The in vivo model (Wistar rats) showed neuroprotective, hepatoprotective and seric antioxidant actions of grape juices in young rats. In oldest rats, antigenotoxic activity was found. These studies demonstrated important correlations between beneficial activities and polyphenolic content, mainly related to resveratrol and catechin, nonflavonoid and flavonoid compounds, respectively. Since grape juice is a complex mixture of compounds, involving these polyphenols were carried out in order to analyze their isolated influence on S. cerevisiae yeast model. Our results suggest that both polyphenols when applied in similar amountm have the same antioxidant potential. However, when studying strains proficient and deficient in antioxidant defense systems, the damages from stressor agents are reverted by both polyphenols, mainly under the action of catalase enzyme. Further studies with specific models of certain diseases or even with humans are needed. Our findings demonstrated that grape juice is a food rich in polyphenols, vitamin C and minerals which plays important in vitro and in vivo antioxidant activities.