Natural organic substances with antioxidant activity in dietary vegetables.

During the past two decades, epidemiological studies have pointed out clear relations between diet, chronic diseases (cardiovascular, neoplastic, inflammatory, and neurodegenerative pathologies and aging) and the protective effects following the consumption of vegetables and fruits. For a long time antioxidant vitamins and beta-carotene were considered responsible for the protective effects. In recent years it became apparent that other dietary vegetable components, in particular phenols, which are ubiquitous in plants, can strongly contribute to the positive effects of vegetable foods. Reactive oxygen sunstances (ROS) and reactive nitrogen substances (RNS), in particular free radicals, initiate and accelerate lipid peroxidation, which in foods damage the flavour of fat and oil products and in living organisms they attack and damage the most important biological molecules, such as DNA, lipids, proteins, carbohydrates, and alter their chemical structure and biological functions. The importance of the availability of natural antioxidants that can contrast the action of free radicals both in chemical and in biological systems, promoted the investigation of plant materials. Plant materials are known to contain many different antioxidant components that can act as free radical scavengers and singlet oxygen quenchers. Among these ones plant foods are particularly interesting because it is demonstrated that consumption of fruits and vegetables protects living organisms from oxidative damage. The aim of this study is to investigate the specific antiradical activities both peroxyl- and hydroxyl-radicals of some vegetables commonly used in the Mediterranean diet, and the influence of technological treatment on such activities.