Phytochemicals, proximate analysis and identification of compounds in cowpea (Vigna unguiculata (Walp) L.) seeds using gas chromatography-mass spectrometry

Abstract

Vigna unguiculata seeds are used as food and contain different primary metabolites, however the identification of its secondary metabolites in the semi-polar solvent-dichloromethane could confirm some of its ethno-medicinal claims. The aim of this work was to determine the proximate parameters, phytochemical contents and identify the compounds in the dichloromethane extract of the seed of Vigna unguiculata. Proximate analysis and phytochemicals were determined using standard established methods while identification of the compounds in the dichloromethane extract was done by gas chromatography-mass spectrometric (GC-MS) analysis. Secondary metabolites include alkaloid, flavonoids, glycosides, phenols, saponins, sterols and triterpenoids. Primary metabolites such as carbohydrate content (48.32±0.34) %, moisture content (10.63±0.04) %, crude protein (25.78±0.04) %, fat content (0.65±0.05) %, crude fibre (6.48±0.05) % and ash content (2.78±0.07) % were reported. Twenty-one compounds were identified in the dichloromethane seed extract, they include fatty acids, esters, alcohols and ketones. Cowpeas contain both primary and secondary metabolites that have documented pharmacological applications.