IDENTIFICATION AND QUANTIFICATION OF PHENOLIC COMPOUNDS AND ANTIOXIDANT ACTIVITY IN COWPEAS OF BRS XIQUEXIQUE CULTIVAR

Regilda Saraiva Dos Reis Moreira-Araújo,Marcos Antonio Da Mota Araújo,Cíntia Pereira Da Silva,Rosana Aparecida Manólio Soares,José Alfredo Gomes Arêas,Geni Rodrigues Sampaio

doi:10.1590/1983-21252018v31n124rc

Abstract

ABSTRACT Cowpea (Vigna unguiculata [L.] Walp.) is one of the most important legumes produced in tropical and subtropical regions throughout the world, especially in the developing countries in Africa, Latin America, and Asia. It is the main source of protein, calories, dietary fiber, minerals, and vitamins for a large segment of the world population. Cowpea is also a potential functional food with a range of bioactive compounds, including phenolic compounds. This legume is grown mainly in the North and Northeast regions of Brazil, but is also consumed in other regions, and is thus important for the farmers who depend on this crop for income. This study identified and quantified phenolic compounds in the cowpea cultivar BRS Xiquexique. Such quantification reveals the functional characteristics of cowpeas, mainly as a source of antioxidants, which will be essential to add value to this food and to expand its forms of consumption. The extracts were analyzed using an HPLC model LC-20AT, equipped with a manual injector. For the HPLC analysis, standard solutions were prepared with pure phenolic acids such as gallic acid, quercetin, caffeic acid, chlorogenic acid, ferulic acid, p-coumaric acid, catechin, and epicatechin. The major phenolic compounds identified were catechin (2.07± 0.329 mg 100 g-1), epicatechin (0.48 ± 0.130 mg 100 g-1), gallic acid (67.19 ± 6.200 mg 100 g-1), ferulic acid (32.07 ± 0.753 mg 100 g-1), and chlorogenic acid (3.08 ± 0.489 mg 100 g-1). We observed that the BRS Xiquexique cultivar contains functional phenolic compounds, especially gallic acid and ferulic acid, demonstrating the antioxidant potential of cowpea.

Highlights

Studies of antioxidants in foods are currently widespread because of their action in delaying or inhibiting oxidative damage to cells
The determinations were performed in triplicate or quadruplicate, and the data obtained were presented as means and standard deviation
Based on a study by Marathe et al (2011), which classified legumes such as common bean, cowpea, chickpeas, soybeans, and peas into three different groups according to their phenolic compound content, the raw cowpea cultivar analyzed in the present work can be classified under moderate phenolic content (> 100 and < 200 mg GAE 100 g-1)

Summary

INTRODUCTION

Studies of antioxidants in foods are currently widespread because of their action in delaying or inhibiting oxidative damage to cells. Antioxidants are substances that can delay or inhibit oxidative damage, preventing the initiation or propagation of oxidation chain reactions, thereby preventing diseases caused by free radicals in the body (SILVA; ROCHA; CANNIATTI-BRAZACA, 2009) These radicals are unstable and highly reactive molecules, produced naturally via metabolic processes or biological dysfunction, which are combated by antioxidants, such as phenolic compounds and flavonoids (BARREIROS; DAVIS, 2006), which are produced in the body or obtained through the diet. The cowpea (Vigna unguiculata [L.] Walp.) is an important legume produced in largely in Africa, Latin America, and Asia It is a rich source of proteins, calories, dietary fiber, minerals, and vitamins for a large number of people globally (PHILLIPS et al, 2003; CARVALHO et al, 2012). To determine the total phenolics, 2 mL of deionized water was added to a 10 mL volumetric flask, followed by addition of 100 μL of the extract and 0.5 ml of the Folin-Ciocalteu reagent. After incubating for 2 hours at room temperature and protecting from light with aluminum foil, the absorbance at 765 nm was measured in a 10 mm cuvette according to the methodology of Singleton and Rossi (1965)

MATERIAL AND METHODS

RESULTS AND DISCUSSION

Method DPPH ABTS