A plausible chemical mechanism of the bioactivities of mangiferin

Abstract

A plausible chemical mechanism of the observed bioactivities of mangiferin, a naturally occurring C-glucosylxanthone (1), is depicted. The mechanism focuses its capacity to provide cellular protection as an antioxidant and a radical captodative agent. Mangiferin performs its antioxidant function at different levels of systemic oxidation sequence. As far as membrane lipid peroxidation and consequent immunomodulations are concerned, it acts by (i) decreasing localized O2 concentration there-by generating, in concert, mangiferin phenoxy radicals (2); (ii) by binding metal ions (Fe2+/3+) in forms 3 and 4 that will not allow the generation of such tissue damaging species as hydroxyl and highly reactive oxo-ferryl radicals; (iii) regulating polymer chain lengthening (membrane lipids) by interacting with the reactive oxygen species; (iv) chain breaking (by 2), i.e. scavanging intermediate radicals (such as lipid peroxy and alkoxy radicals) to prevent continued H abstraction from cellular lipid molecules; and (v) maintaining systemic oxidant-antioxidant balance (by 1 and 2). Chemical evidence in support of the above postulate has been sought and obtained in the form of a complex polymer (5) through the intermediates 2 to 4.