2399 Research Article Received: 16 August 2010 Revised: 6 April 2011 Accepted: 11 April 2011 Published online in Wiley Online Library: 20 May 2011 (wileyonlinelibrary.com) DOI 10.1002/jsfa.4476 Antioxidant activity and free radical- scavenging capacity of a selection of wild-growing Colombian plants Juan C Argoti, a,b Sof´ ıa Salido, c Pablo J Linares-Palomino, c Bernardo Ram´ ırez, d Braulio Insuasty a * and Joaqu´ ın Altarejos c * Abstract BACKGROUND: The replacement of some synthetic food antioxidants by safe natural antioxidants has fostered research on the screening of raw materials to find new vegetable sources of antioxidants. In this study the antioxidant activity of eight wild-growing Colombian plants was assessed by four complementary assays. RESULTS: An evaluation of the antioxidant activity of ten ethanolic extracts from Baccharis chilco, Cinnamomum triplinerve, Ilex laurina, Lachemilla orbiculata, Lepechinia conferta, Quercus humboldtii, Rubus urticifolius and Tephrosia cinerea was carried out. Furthermore, the total phenolic content was determined by the Folin–Ciocalteu method, and the relationship between phenolic content and activity was also statistically investigated. Cinnamomum triplinerve, L. conferta and I. laurina were found to have the highest phenolic contents. Baccharis chilco, C. triplinerve, I. laurina, L. conferta, Q. humboldtii and R. urticifolius showed higher radical-scavenging activity (DPPH and superoxide assays) than commercial rosemary oleoresin (reference). Lachemilla orbiculata and R. urticifolius showed higher antioxidant activity (β -carotene-bleaching test) than the reference. The protection factor of all studied plant extracts was below that of the reference according to the Rancimat test. CONCLUSION: On the basis of the results obtained, C. triplinerve, Q. humboldtii and R. urticifolius seem to be the most promising species for further investigation in order to identify the compounds responsible for their activity. c  2011 Society of Chemical Industry Keywords: Colombian plants; radical-scavenging activity; antioxidant activity; total phenolic content INTRODUCTION It is accepted that an excess of reactive oxygen species (ROS) in living organisms plays a causative role in the initiation and development of a great number of degenerative diseases. ROS are also the main factor responsible for the complete spoilage of lipid-containing foods. For these reasons, antioxidants are of great importance nowadays in medicine and in the food industry. However, since some synthetic antioxidants commonly used to preserve foods, such as tert-butylhydroquinone and tert-butyl-4- hydroxyanisole, are suspected to be toxic, 1 much attention is paid to both natural antioxidants and the search for new sources of these naturally occurring compounds. Thus a huge amount of work has been developed to find interesting sources of potentially safe natural antioxidants in many aromatic and medicinal plants 2 and even in agroindustrial waste materials. 3 In this context the present work is aimed at the study of the antioxidant and radical-scavenging activities of the ethanolic extracts from eight plants growing wild in Colombia. The following plants were selected for this investigation: Baccharis chilco, Cinnamomum triplinerve, Ilex laurina, Lachemilla orbiculata, Lepechinia conferta, Quercus humboldtii, Rubus urticifolius and Tephrosia cinerea. All of them have traditionally been used by people since ancient times (Table 1). To our knowledge, there is no information on the chemical composition of these plants, with the exception of L. conferta and T. cinerea, whose essential oils from aerial parts have already been analysed, 4,5 and C. triplinerve, whose leaves have been found to contain two cinnamoyl derivatives. 6 However, the antioxidant properties of several species of these eight genera (with the exception of Lachemilla) have been reported. Indeed, the plants studied in this work were initially selected on the basis of (a) the almost complete absence of ∗ Correspondence to: Joaqu´ ın Altarejos, Departamento de Qu´ ımica Inorg´ anica yOrg´ anica, Facultad de Ciencias Experimentales, Universidad de Ja´ en, E-23071 Ja´ en, Spain. E-mail: jaltare@ujaen.es Braulio Insuasty, Grupo de Investigaci´ on de Compuestos Heteroc´ ıclicos, Departamento de Qu´ ımica, Universidad del Valle, A.A. 25360 Cali, Valle del Cauca, Colombia. E-mail: brainsu@univalle.edu.co a Grupo de Investigaci´ on de Compuestos Heteroc´ ıclicos, Departamento de Qu´ ımica, Universidad del Valle, A.A. 25360 Cali, Valle del Cauca, Colombia b Departamento de Qu´ ımica, Facultad de Ciencias Naturales, Exactas y de la Educaci´ on, Universidad del Cauca, Cauca, Colombia c Departamento de Qu´ ımica Inorg´ anica y Org´ anica, Facultad de Ciencias Experimentales, Universidad de Ja´ en, E-23071 Ja´ en, Spain d Departamento de Biolog´ ıa, Facultad de Ciencias Naturales, Exactas y de la Educaci´ on, Universidad del Cauca, Cauca, Colombia J Sci Food Agric 2011; 91: 2399–2406 www.soci.org c  2011 Society of Chemical Industry