Antioxidant activities of prickly pear ( Opuntia ficus indica) fruits and its betalains: betanin and indicaxanthin.

Phytochemicals and phytomedicines are now an expanding research fields. A great number of active agents occurring in plants and herbs have been discovered, which is fundamental to find a rationale for the health effects of these herbs, in many cases used for centuries as traditional remedies. The knowledge of the mechanisms and molecular basis of their action is the final objective to understand the mode of action of the discovered principles. Studies on the bioactivity of cactus pear are very recent and results obtained so far, while exciting, now generate new questions. In vivo studies on healthy humans showed a strong protection of the body antioxidant system, and a marked reduction of plasma level of markers of oxidative stress, by regular consumption of moderate amounts of cactus pear fruits. Betanin and indicaxanthin, two bioavailable, anti-radical and antioxidant betalain pigments, with proved activity in biological environments occur in the fruit. However distinguishing protective effects of foods rich of antioxidant molecules from direct effect of the molecules themselves is essential. At present it is not possible to assess to what extent and how these pigments may be involved in the in vivo observed effects and the molecular mechanisms underlying these effects. This review summarizes findings to date in many chemical and biological systems in vitro, as well as in humans, obtained with purified betalains and with cactus pear fruit edible pulp.