Phenolics, betacyanins and antioxidant activity in Opuntia joconostle fruits Obed Osorio-Esquivel a , Alicia-Ortiz-Moreno a, ⁎, Valente B. Álvarez b , Lidia Dorantes-Álvarez a , M. Mónica Giusti b a Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Departamento de Ingeniería Bioquímica, Carpio y Plan de Ayala S/N, 11340, Distrito Federal, Mexico b Food Science Department, The Ohio State University, 2015 Fyffe Road, 43210, Columbus, OH, USA abstract article info Article history: Received 23 November 2010 Accepted 11 February 2011 Keywords: Opuntia joconostle Xoconostle Betalain Isobetanin Free phenolic acids Antioxidant activity Sour prickly pears (xoconostles) are fruits from Opuntia joconostle cactus, which are cultivated in the central Mexico area. Phenolic and pigment content in various parts of O. joconostle fruits were analyzed. The antioxidant activity of a methanolic extraction and different semi-purified fractions were also evaluated by the DPPH + method. Xoconostle fruits were obtained from a commercial orchard in Mexico State. Fruits were analyzed as whole fruit and each fruit part including pericarp, mesocarp and endocarp. Samples were homogenized and kept at 4 °C until sample preparation. Total phenolic content and total flavonoid content varied among the different parts of the fruit. The highest amount of phenolic compounds and total flavonoids content were found in pericarp 2.07 mg gallic acid equivalents (GAE)/g fresh weight (FW) and 0.46 mg(+)- catechin equivalents (CE)/g FW respectively. Seven phenolics were identified as protocatechuic, 4-hydroxybenzoic, caffeic, vanillic and syringic acids, rutin, and quercetin. The color of the fruit parts was mainly due to the presence of betacyanins. The betacyanin concentration was higher in the endocarp (23.03 mg betanin equivalents/100 g fresh weight) than in the pericarp and mesocarp. Betacyanins were identified by HPLC-PDA-MS as betanin, isobetanin, betanidin, isobetanidin, and phyllocactin. Methanolic extracts and semi-purified fractions A (phenolics and flavonols) and B (betacyanins) of xoconostle showed high antioxidant activity mainly in the pericarp. These results suggest that xoconostle is a rich source of antioxidant compounds such as phenolic compounds and betacyanins. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction The fruit of Opuntia joconostle cactus, known as xoconostle (sour- prickly pear), is used as a condiment in Mexican cuisine, and in the elaboration of candies, jellies and beverages. The fruit has a light red- pink colored pericarp, a yellow-pink color, and succulent mesocarp, and a deep red colored endocarp that contains small brown seeds. The xoconostle may remain in the plant for several months without deteriorating, and it can even be kept for several weeks in a dry and cool environment without loosing flavor or moisture. (Reyes-Agüero, Aguirre, & Valiente-Banuet, 2006). O. joconostle is cultivated in the central area of Mexico throughout the year. The plant produces 60 g rounded fruits with a diameter of 4–5 cm. Xoconostles have been used in folk medicine as a treatment for diabetes, hypertension, obesity and respiratory ailments (Zavaleta- Beckler, Olivares-Orozco, Montiel-Salero, Chimal-Hernández, & Scheinvar, 2001). Recently, Pimienta-Barrios, Méndez-Moran, Ramirez-Hernandez, García de Alba-García, and Domínguez-Arias (2008) reported that the consumption of O. joconostle pericarp caused a reduction in cholesterol levels, a gradual decrease on seric glucose levels and an increase in seric insulin levels. O. joconostle fruit is consumed since pre-Hispanic times especially in semi-arid regions in the central area of Mexico. Xoconostle is commonly peeled and the mesocarp is consumed in sauces, or other national dishes (Reyes-Agüero et al., 2006). The endocarp is usually discarded. Recently, xoconostle fruit has been processed at a small scale in jams, candies, juices and with powder chili. Cactus fruits have attracted the attention of national and inter- national researchers due to its commercial value. Phytochemical properties of O. joconostle have not been studied, thus it is important to identify the main biocompounds of the fruit. Prickly pears from other Opuntia cactus owe their color to the presence of betalains, which are N-heterocyclic water-soluble pig- ments deposited in vacuoles. Betalamic acid is the common precursor of these compounds consisting of a 1,7-diazaheptamethin system, an extended π-electron system exhibiting a canary yellow color. Betalamic acid may be condensed with cyclo-Dopa to yield betanidin, the common precursor aglycon of the red betacyanins. Betanidin in turn may be glycosylated and/or acylated, yielding 29 genuine structures known to date. Due to stereoisomerism at C 15 their number is doubled, except for neobetanin (14,15-dehydrobetanin) which is devoid of the chiral center at C-15 (Stintzing, Schieber, & Carle, 2001). The most important betalains in cactus are betacyanins and betaxanthins. Betacyanins are known to display two absorption Food Research International 44 (2011) 2160–2168 ⁎ Corresponding author. Tel.: +52 55 5729 6300x62372; fax: +52 55 57296300x62359. E-mail address: ortizalicia@hotmail.com (Alicia-Ortiz-Moreno). 0963-9969/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2011.02.011 Contents lists available at ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres