PHYTOTHERAPY RESEARCH Phytother. Res. 17, 713 – 716 (2003) Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/ptr.1050 Copyright © 2003 John Wiley & Sons, Ltd. Received 1 March 2001 Accepted 11 May 2001 John Wiley & Sons, Ltd. Antioxidant Properties of Extracts from Alchornea laxiflora (Benth) Pax and Hoffman Antioxidant Properties of Alchornea Laxiflora E. Olatunde Farombi, 1 * Oluyemisi O. Ogundipe, 2 E. Samuel Uhunwangho, 1 Mary A. Adeyanju 1 and J. Olarenwaju Moody 2 1 Drug Metabolism and Toxicology Research Laboratories, Department of Biochemistry, College of Medicine University of Ibadan, Ibadan, Nigeria 2 Department of Pharmacognosy, Faculty of Pharmacy, College of Medicine University of Ibadan, Ibadan, Nigeria The antioxidant activities of the leaf and root extracts of Alchornea laxiflora, a plant used locally for the preservation of food items in Nigeria, were evaluated using the ferric thiocyanate method, horseradish per- oxidase catalysed oxidation of 2,2 azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), β β -carotene linoleate model system and Fe 2+ /ascorbate/H 2 O 2 -induced rat liver microsomal lipid peroxidation. The crude hexane root (HR), methanol root (MR), methanol leaf (ML) and hexane leaf (HL) extracts from A. laxiflora were tested for antioxidant activities. Antioxidant activity decreased in the following order: HR (76.4%), MR (63%), ML (40%) and HL (38%) at a concentration of 0.05% v/v. The antioxidant activity of HR compared to that of butylated hydroxyanisole (BHA) (80%), a standard antioxidant. The total antioxidant activity (TAA) of the crude extracts suggests that activity is highest in the HR compared with the others. The TAA value was estimated to be 8.0 measured as mM of vitamin C equivalent. Six column chromatographic fractions (FI–FVI) from HR showed antioxidant activity to varying extents in the β β -carotene model system in the order of FII > FI > FVI > FIII > FIV > FV. FII exhibited the highest antioxidant activity in all model systems utilized, it recorded a higher antioxidant activity than BHA and quercetin in the β β -carotene linoleate and Fe 2+ /ascorbate/H 2 O 2 . TLC analysis of fraction II revealed the presence of terpenoid compounds (radiant green coloration with 2,4 dinitrophenylhydrazine). Our results suggest that A. laxiflora contains potent natural antioxidants and may therefore be relevant in the preservation of lipid food products, which are prone to oxidation and rancidity. Copyright © 2003 John Wiley & Sons, Ltd. Keywords: Alchornea laxiflora; antioxidants; terpenoids; flavonoids. INTRODUCTION The plants of the Euphorbiaceae consist of several species of considerable economic importance used as foodstuffs, medicinal products and in industry (Rizk, 1986). Curative effects have been attributed to many of these plants since antiquity, for instance Euphorbia fischerriana has been used in Chinese medicine for more than 2000 years as an anti-tumour drug (Schroeder et al., 1980). Certain other species of the Euphorbiaceae have been described in homeopathic pharmacopoeias (Nahrstedt et al., 1982). A survey of the chemical constituents of several genera in this fam- ily show that the triterpenoids are the main classes of substances of interest to the phytochemist, followed by the flavonoids and then the alkaloids (Ogundipe, 1999). Alchornea laxiflora (Benth) Pax and Hoffman (Euphorbiaceae) is a shrub or understorey tree found in northern and southern Nigeria as well as in the Cam- eroons and in southeastern Africa. It is used in food preservation, the decoction of the leaves is also used in the treatment and management of infectious diseases and administered to children with teething problems (Adewole, 1993, personal communication). The stem and branchlets are used in Nigeria as chewing sticks. Phytochemical screening of the powdered leaf and root samples of A. laxiflora showed the presence of alkaloids, cardiac glycosides, saponins and phenolic compounds with a higher concentration residing in the leaves than in the roots (Ogundipe et al., 1999). A preliminary investigation into the crude and purified fractions of the leaves and roots revealed the presence of potent antiinflammatory and antimicrobial activities (Ogundipe, 1999). The use of A. laxiflora in the preservation of food items and its other medicinal uses have stimulated our interest in evaluating the antioxidant activity of differ- ent parts of the plants. We therefore report for the first time the antioxidant activities of the leaf and root extracts of A. laxiflora using the ferric thiocyanate method, horseradish peroxidase catalysed oxidation of 2,2 azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), β-carotene linoleate model system and rat liver microsomal lipid peroxidation assay. MATERIALS AND METHODS Chemicals. β-carotene was a generous donation of Dr George Britton of the School of Biological Sciences, University of Liverpool, UK. Butylated hydroxylanisole (BHA), linoleic acid, Tween 40 emulsifier, 2,2-azinobis- (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), * Correspondence to: Dr E. Olatunde Farombi, Department of Bio- chemistry, University of Ibadan, Nigeria. Fax: 234 2 8103043. E-mail: ofarombi@skannet.com