Antioxidant activity, phenolic compounds and anthocyanins content of eighteen strains of Mexican maize Leticia X. Lopez-Martinez a , Rosa M. Oliart-Ros a , Gerardo Valerio-Alfaro a , Chen-Hsien Lee b , Kirk L. Parkin b , Hugo S. Garcia a, * a UNIDA, Instituto Tecnolo ´gico de Veracruz, M.A. de Quevedo 2779, Col. Formando Hogar, Veracruz, Ver. 91897, Mexico b Department of Food Science, University of Wisconsin-Madison, 1605 Babcock Drive, Madison, WI 53706, United States article info Article history: Received 1 February 2008 Received in revised form 15 October 2008 Accepted 20 October 2008 Keywords: Antioxidants Pigmented Corn Phenolics abstract Free-radical scavenging, reducing activity and some phytochemical content (total phenolic, anthocyanin and ferulic acid) of eighteen Mexican maize phenotypes were determined. Total phenolic contents ranged from 215.8 to 3400.1 mg gallic acid/100 g of whole grain flour and total anthocyanins ranged from 1.54 to 850.9 mg cyanidin-glucoside equivalents/100 g of whole grain flour. Most of the phenolics in grain were in the bound form (ca. 85%), while anthocyanins were the major free phenolic compounds. Among the different samples, bound phenolic extracts of corn appeared to have greater anti-radical and reducing activities than free phenolic extracts from the same grain samples when tested at a normalized phenolic concentration. The phenotypes Veracruz 42 and AREQ516540TL exhibited the greatest activities and these purple-colored strains were most enriched in anthocyanins. Extracts from a red-colored phenotype Pinto were also among the most effective at exhibiting anti-radical activities. Differences in free-radical scavenging and reducing activities appeared to be dependent on the unique profile of anthocyanins and other phenolics in each phenotype. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Corn (Zea mays L.) is a widely consumed cereal in Mexico and Central America mainly in the form of products such as tortilla and tortilla chips (De la Parra, Serna, & Liu, 2007), as well as typical beverages as chicha morada which has been linked to increased health benefits in Peru (Brack-Egg, 1999). Pigmented corn contains anthocyanins or carotenoids, and phenolic compounds which are phytochemicals synthesized in the plant by secondary metabolism; although these compounds are considered nonnutritive, interest in antioxidant and bioactive properties has increased due to their health benefits (Heinonen, Meyer, & Frankel, 1998; Rice-Evans & Miller, 1996; Setchell & Aedin, 1999). Epidemiological and in vitro research suggests an inverse rela- tionship between consumption of fruits and vegetables and the incidence of various chronic and degenerative diseases that come with aging such as cancer, cardiovascular diseases, cataracts, and brain and immune dysfunction (Ames, Shigenaga, & Hagen, 1993). The health benefiting properties of these plant metabolites have been related not only to high antioxidant and anti-radical activi- ties, but also to several other biological properties, such as antimutagenic or estrogenic activities, inhibition of enzymes, and induction of detoxification enzymes such as glutathione transferase and quinone reductase (Rondini, Peyra-Maillard, Marsser-Baglieri, & Berset, 2002; Tsuda, Horio, Uchida, Aoki, & Osawa, 2003). Pigmented Mexican maize is a crop that to the best of our knowledge has not been often examined for properties related to health promotion in humans. Because maize is subjected to extensive processing into industrial (by)products, studies have been conducted on various fractions or derivatives of maize, including bran and oil fractions, as well as extracts of stigmata of flowers (maize silk) (Maksimovic, Malencic, & Kovacevic, 2005). Maize of different phenotypes has been shown to exhibit different antioxidant activities and profiles. Several studies have reported a range of bioactivities of maize components, the antioxidant and anticarcinogenic effect of white corn polyphenolics such as ferulic and r-coumaric acid along with their respective derivatives (Andreasen, Kroon, Williamson, & Garcia-Conesa, 2001; Kroon & Williamson, 1999; Rondini et al., 2002). It has been found that purple, blue and red pigmented maize inhibits colorectal carcinogenesis in male rats (Hagiwara et al., 2001), and possesses antimutagenic (Yoshimoto, Okuno, Kumagi, Yoshinaga, & Yamakawa, 1999) and radical scavenging activities (Oki et al., 2002). These bioactivities were associated with antho- cyanins present in these crops. * Corresponding author. Tel.: þ52 229 934 5701; fax: þ52 229 934 1478. E-mail address: hsgarcia@itver.edu.mx (H.S. Garcia). Contents lists available at ScienceDirect LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt 0023-6438/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.lwt.2008.10.010 LWT- Food Science and Technology 42 (2009) 1187–1192