D. Villaño

Radical scavenging ability of polyphenolic compounds towards DPPH free radical.

Free radical scavenging activity of different polyphenolic compounds commonly present in wine has been evaluated using DPPH method. The experiments were performed with different amounts of phenols within the linear interval of response and with an excess of DPPH in all cases. In these conditions, for most of the compounds tested, the reaction was biphasic. Total stoichiometry values n confirm the implication of more than one step in the process. Flavan-3-ol compounds showed the highest values, especially procyanidins B1 (9.8) and B2 (9.1). In this family, n values coincide with the number of hydroxyl groups available. EC(50) and TEC(50) parameters have been calculated. EC(50) values are extremely diverse, being the procyanidins B1 and B2 the most potent scavenging compounds and resveratrol the less one. TEC(50) considers the rate of reaction towards the free radical. (+)-Catechin and (-)-epicatechin are the phenolic compounds that need more time to react. In contrast, caftaric and caffeic acids are the phenolic acids that react more rapidly. Antioxidant efficacy (AE) is a parameter that combines both factors. Compounds as kaempferol, with a high EC(50) value, could be considered as an antioxidant with low relevance, but instead shows the highest AE value of the phenolic compounds tested, due to its fast rate of reaction, what is of great biological importance.

Antioxidant Activity of Phenolic Compounds: From In Vitro Results to In Vivo Evidence

Over last decade an increasing interest for antioxidants in foods has arisen. The healthy properties of antioxidants related to the prevention of degenerative diseases are the main cause of this boom. An antioxidant prevents the oxidation process, the initial step of development of degenerative diseases, cancer and many others. Literature encompasses analytical methodology development to assess antioxidant properties of foods and beverages. The screening of antioxidant activity of foodstuffs is the subject of a large number of articles. Special interest has been addressed to wine, tea and chocolate. However, the crucial key in the prevention of disease is the action these antioxidants exert after their consumption. Studies involving human subjects are scarce due to the requirements of availability of volunteers and conditions to test are limited. This review summarizes data related to in vitro antioxidant activity of foods, emphasizing the main role of phenolic compounds. A critical comparison is realized between the biological significance of these values and the biological significance of in vivo measurements. In addition, the Plasma Antioxidant Capacity is evaluated and selected as biomarker for in vivo antioxidant status of human organism. In a second part, data collected from different intervention studies performed up to date are compiled and discussed. This review summarized data related to in vitro antioxidant activity of foods, emphasizing the main role of phenolic compounds. A critical comparison is realized between the biological significance of these values and the biological significance of in vivo measurements. In addition, the Plasma Antioxidant Capacity is evaluated and selected as biomarker for in vivo antioxidant status of human organism. In a second part, data collected from different intervention studies performed up to date are compiled and discussed. The original contribution of this work is to compile data of Plasma Antioxidant Capacity after dietetic intervention studies taking into account the portion of food ingested. In addition, we calculated the antioxidant compounds content (phenolic content, ascorbic acid, vitamin E and carotenoids) contained in each food ingested to evaluate better their impact in Plasma Antioxidant Capacity. Intervention studies are grouped by the length of intervention and type of food ingested. Results reported in literature reveal that the increment in Plasma Antioxidant Capacity largely depends on analytical method used.

Acute intake of red wine does not affect antioxidant enzymes activities in human subjects.

The purpose of this work was to test if the acute intake of red wine has an effect on the activity of antioxidant enzymes. Eight healthy, non-alcoholic, non-smoking human volunteers took part in the study. Ethical approval for the study was obtained from the Ethical Research Committee of the University Hospital Virgen Macarena from Seville. Each subject fasted 12-14 hours before the experiment started. Volunteers were asked to consume 300 mL of red wine in 5 minutes. Venous blood sample was obtained by antecubital venipuncture, with heparin vacutainer. Blood extraction was performed before wine ingestion (baseline value) and 30, 55, and 120 minutes after wine intake. Blood samples were immediately centrifuged at 12,000 x g for 3 minutes, avoiding unnecessary exposure to light. Antioxidant enzymes under study were: superoxide dismutase in erythrocytes, glutathione peroxidase in whole blood, and glutathione reductase in plasma. Determinations were performed spectrophotometrically with commercial available enzymatic kits. No statistically significant changes were observed on the activities of the enzymes superoxide dismutase, glutathione peroxidase, and glutathione reductase assayed at any of the times after wine intake. The intake of red wine did not modify the short-term activity of antioxidant enzymes.