Antioxidant activity of <i>α</i> and <i>β</i>-amyrin isolated from <i>Myrcianthes pungens</i> leaves

Abstract

Brazil has a great variety of native plants which could be explored and among them guabiju (<i>Myrcianthes pungens</i>) stands out. Thus, this study consisted of isolating pentacyclic triterpenes, <i>α</i> and <i>β</i>-amyrin from guajibu leaves, and determine the antioxidant activity.The leaves were dried, pulverized and submitted to a dynamic maceration process with ethanol 96° GL, concentrated to obtain crude leaf extract (CLE). CLE was eluted with dichloromethane until total depletion, resulting in a dichloromethane fraction (FRDicl) which was concentrated and analyzed by GC/MS and NMR. The result of the chemical analysis revealed the presence of pentacyclic triterpenes of oleanane (<i>β</i>-amyrin), and ursane (<i>α</i>-amyrin) groups. The <i>β</i>-carotene bleaching method revealed a high antioxidant activity for the CLE as well as for FRDicl. The antioxidant protection equivalent to the trolox was of 137 and 129%, respectively at 500 µg/mL. The antioxidant potential of FRDicl can be explained by the presence of <i>α</i> and <i>β</i>-amyrins.