Radical scavenging ability of some compounds isolated from Piper cubeba towards free radicals

Abstract

<jats:title>Abstract</jats:title><jats:p>The purpose of this study was to identify the antioxidant activity of 16 compounds isolated from <jats:italic>Piper cubeba</jats:italic> (CNCs) through the extent of their capacities to scavenge free radicals, hydroxyl radical (HO<jats:sup>•</jats:sup>), superoxide anion radical (<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/bio1209-math-0006.gif" xlink:title="equation" />) and 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH<jats:sup>•</jats:sup>), in different systems. Electron paramagnetic resonance (EPR) and 5,5‐dimethyl‐1‐pyrroline‐<jats:italic>N</jats:italic>‐oxide, DMPO, as the spin trap, and chemiluminescence techniques were applied. Using the Fenton‐like reaction [Fe(II) + H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>], CNCs were found to inhibit DMPOOH radical formation ranging from 5 to 57% at 1.25 mmol L<jats:sup>−1</jats:sup> concentration. The examined CNCs also showed a high DPPH antiradical activity (ranging from 15 to 99% at 5 mmol L<jats:sup>−1</jats:sup> concentration). Furthermore, the results indicated that seven of the 16 tested compounds may catalyse the conversion of superoxide radicals generated in the potassium superoxide/18‐crown‐6 ether system, thus showing superoxide dismutase‐like activity. The data obtained suggest that radical scavenging properties of CNCs might have potential application in many plant medicines. Copyright © 2010 John Wiley &amp; Sons, Ltd.