The gastrointestinal tract as the first interface for intracellular activity of food antioxidants

The gastrointestinal tract is exposed to a number of pro-oxidant conditions and several gastrointestinal diseases are related to oxidative stress. The preservation of the gastrointestinal redox balance is of pivotal importance for the health status of the organism. It depends on a dynamic system involving antioxidant enzymes, as well as non-enzymatic molecules some of which derive from the diet. This work focuses on the intestinal epithelium and its aim was to explore the intracellular ROS scavenging activity of intracellularly absorbed food antioxidants. Freshly isolated intestinal explants obtained from different experimental animal models were used. They retain the functional and morphological characteristics of the epithelium in vivo. In situ confocal detection on CM-H2DCFDA charged explants experimentally exposed to pro-oxidant conditions was applied. Phenolic phytochemicals, such as hydroxytirosol or anthocyanins, commonly found in the Mediterranean diet, were demonstrated in surface enterocytes to cross the plasma membrane and exert a direct intracellular antioxidant activity. The effect was dose and time dependent and was compared with Trolox, synthetic analog of vitamin E. In conclusion, the gastrointestinal epithelium represents the first interface for the intracellular ROS scavenging activity of food antioxidants, and as such it can benefit directly and earlier than other body tissues of the protective action of food antioxidants against pro-oxidant conditions.