Antioxidant activities oftriacontanyl-E-cinnamoatesmetabolites from Caesalpinia volkensii root bark extracts

Abstract

Natural antioxidants have been reported to prevent oxidative damage caused by free radicals generated during biochemical processes and thus useful in prevention of several degenerative diseases. The present study evaluated the antioxidant value of Caesalpinia volkensii Harms (Leguminosae) root bark that is reported to have several ethno-medicinal applications. In-vitrofree radical scavenging and inhibition bioassays guided chromatographic separation carriedout on the root bark extracts resulted into isolation of three cinnamic acid esters, namely triacontanyl-E-ferulate (1), tricontanyl-(E)-caffaete (2) and 30΄-hydroxytriacontanyl-(E)-ferulate (3) were isolated, along with caesaldekarin C (4) and 5-hydroxyvinhaticoic acid (5) from the potent antioxidant ethyl acetate extract. The compounds were identified using spectroscopic techniques. Compounds 1, 2and 3exhibited significant (p≤0.05) inhibition of free radical generation in xanthine oxidase systems, scavenging of superoxide anion (O2 .−), inhibition of hydroxyl radical (•OH) and inhibition of microsomal lipid peroxidation with comparable LC50 to those of respective reference standards. This is the first report on antioxidant principles from C. volkensii and the result thus support in part the folklore use of the plant root bark to manage human ailments.