Evaluation of Nutritive Potential and Phytochemical Constituents of Aqueous and Methanolic Extracts of Vernonia amygdalina

Abstract

This study was conducted to evaluate and compare the proximate analysis and phytochemical constituents of fresh, aqueous and methanolic extracted leaf samples of sun-dried, air-dried and oven-dried Vernonia amygdalina leaves. The highest crude
protein (CP) content was recorded for the concentrated aqueous extract of Vernonia amygdalina (44.92%) followed by the non-treated sun-dried leaves of the plant material (25.62%); The crude fibre (CF) content was highest (5.25%) in the non-treated ovendried Vernonia amygdalina and lowest in the concentrated extract (0.90%) while there seem to be little or no significant difference (P<0.05) in all aqueous and methanolic extracted leaves of Vernonia amygdalina. Ether Extract (EE) is lowest in the concentrated extract (0.73%) and highest (18.24%) in the air-dried leaves of Vernonia amygdalina. The ash content which is an indication of the mineral content was highest (14.79%) for methanolic extracted oven-dried leaves of Vernonia amygdalina and lowest (9.56% and 3.10%)) in the aqueous extracted oven-dried leaves and concentrated extract
of Vernonia amygdalina respectively. The concentrations of phytochemicals (alkaloids, saponins, tannin, oxalate, cardiac glycosides, phytate and flavonoids) were higher in methanolic extracted samples than in aqueous extracted samples of Vernonia amygdalina, while the concentration of these phytochemicals were generally higher in the non-treated leaves of Vernonia amygdalina (alkaloids (1.27, 3.05, 1.13); saponins (5.44, 6.00, 5.60); oxalate (0.26, 0.29, 0.24); flavonoids (2.12, 2.35, 1.46) than in both aqueous (alkaloids (0.04, 0.27, 0.3); saponins (1.87, 2.12, 1.38); oxalate (0.01, 0.03, 0.01);  flavonoids (0.16, 0.30, 0.07) and methanolic (alkaloids (0.58,0.93, 0.12); saponins (5.37, 5.90, 5.12); oxalate (0.19, 0.23, 0.19); flavonoids (1.05, 1.42, 0.84) extracted leaves of Vernonia amygdalina for the air-dried, oven-dried and sun-dried samples respectively.

Keywords: Vernonia amygdalina, nutrient composition, phytochemical constituents, extraction methods.