Plant Polyphenol Antioxidants and Oxidative Stress

In recent years there has been a remarkable increment in scientific articles dealing with oxidative stress. Several reasons justify this trend: knowledge about reactive oxygen and nitrogen species metabolism; definition of markers for oxidative damage; evidence linking chronic diseases and oxidative stress; identification of flavonoids and other dietary polyphenol antioxidants present in plant foods as bioactive molecules; and data supporting the idea that health benefits associated with fruits, vegetables and red wine in the diet are probably linked to the polyphenol antioxidants they contain.In this review we examine some of the evidence linking chronic diseases and oxidative stress, the distribution and basic structure of plant polyphenol antioxidants, some biological effects of polyphenols, and data related to their bioavailability and the metabolic changes they undergo in the intestinal lumen and after absorption into the organism.Finally, we consider some of the challenges that research in this area currently faces, with particular emphasis on the contributions made at the International Symposium "Biology and Pathology of Free Radicals: Plant and Wine Polyphenol Antioxidants" held July 29-30, 1999, at the Catholic University, Santiago, Chile and collected in this special issue of Biological Researc

A Chilean Berry Concentrate Protects against Postprandial Oxidative Stress and Increases Plasma Antioxidant Activity in Healthy Humans

This study formulated and characterized an antioxidant-rich concentrate of berries (BPC-350) produced in Chile, which was used to perform a crossover study aimed at determining the effect of the berries on the modulation of plasma postprandial oxidative stress and antioxidant status. Healthy male volunteers (N=11) were randomly assigned to three experimental meals: (1) 250 g of ground turkey burger (GTB) + 500 mL of water; (2) 250 g of GTB + 500 mL of 5% BPC-350; (3) 250 g of GTB prepared with 6% BPC-350 + 500 mL of 5% BPC-350. Venous blood samples were collected prior to meal intake and every hour for six hours after intake. Malondialdehyde (MDA), carbonyls in proteins, and DPPH (2,2-diphenyl-1-picrylhydrazyl) antioxidant capacity were quantified in plasma. Significant differences indicated that BPC-350 decreases MDA plasma concentration and protein carbonyls (p<0.05). Additionally, a significant increase in the DPPH antioxidant capacity was observed in Meals 2 and 3 when compared to Meal 1 (p<0.05). The results are discussed in terms of oxidative reactions that occur during digestion at the stomach level and the important effect of oxidative reactions that occur during the thermal processing of red meat

Antioxidant and anti hyperglycemic role of wine grape powder in rats fed with a high fructose diet

BACKGROUND: Metabolic syndrome is a growing worldwide health problem. We evaluated the effects of wine grape powder (WGP), rich in antioxidants and fiber, in a rat model of metabolic syndrome induced by a high fructose diet. We tested whether WGP supplementation may prevent glucose intolerance and decrease oxidative stress in rats fed with a high fructose diet. METHODS: Male Sprague-Dawley rats weighing 180 g were divided into four groups according to their feeding protocols. Rats were fed with control diet (C), control plus 20 % WGP (C + WGP), 50 % high fructose (HF) or 50 % fructose plus 20 % WGP (HF + WGP) for 16 weeks. Blood glucose, insulin and triglycerides, weight, and arterial blood pressure were measured. Homeostasis model assessment (HOMA) index was calculated using insulin and glucose values. A glucose tolerance test was performed 2 days before the end of the experiment. As an index of oxidative stress, thio-barbituric acid reactive substances (TBARS) level was measured in plasma and kidney, and superoxide dismutase was measured in the kidney. RESULTS: Thiobarbituric acid reactive substances in plasma and renal tissue were significantly higher when compared to the control group. In addition, the area under the curve of the glucose tolerance test was higher in HF fed animals. Furthermore, fasting blood glucose, plasma insulin levels, and the HOMA index, were also increased. WGP supplementation prevented these alterations in rats fed with the HF diet. We did not find any significant difference in body weight or systolic blood pressure in any of the groups. CONCLUSIONS: Our results show that WGP supplementation prevented hyperglycemia, insulin resistance and reduced oxidative stress in rats fed with HF diet. We propose that WGP may be used as a supplement in human food as well