Screening of Pigeonpea (Cajanus cajan L.) Seeds for Study of their Flavonoids, Total Phenolic Content and Antioxidant Properties

Abstract

Legumes are an excellent source of compounds having antioxidant, antimutagenic and antiaging activities. Antioxidant based drugs/formulations for prevention and treatment of complex diseases like cancer have attracted a great deal of research interest in natural antioxidants. Therefore, in this study, methanolic crude extract of seed coat, dehulled dal, cooked dal, whole seed were analysed for total phenolics, flavonoids and antioxidant properties of pigeopea (Cajanus cajan L.). It is a health beneficial pulse crop grown in India. Total phenolic contents were determined using a spectrophotometric technique, based on Folin-Ciocalteau reagent and calculated as Gallic Acid equivalents per gram of extract. Hydrophillic and hydrophobic phenols were also estimated. Aluminium chloride colorimetric method was used for flavonoids determination. In-vitro antioxidant activities were screened by ferric thiocyanate (FTC) assay. Further, the free radical-scavenging activities of the extracts were measured as decolourizing activity by trapping of unpaired electron of 2, 2-diphenyl-1-picrylhydrazyl (DPPH). The scavenging efficiencies of the extracts increased with the increasing concentrations. The extract of seed coat showed maximum antioxidant activity with EC50 value 0.26±0.01 mg/ml of extract by DPPH method and 0.59±0.04 mg/ml of extract by FTC method. This maximum antioxidant activity was positively correlated with maximum total phenolic contents observed in seed coat. Results showed that dehulling and cooking reduced the phenolic contents, consequently antioxidant properties too. Based on the observations, it can be concluded that pigeonpea seeds have a potential source of antioxidants of natural origin & applicable in neutraceutical industries.