Phytochemical composition of tubers of selected accessions of African yam bean, Sphenostylis stenocarpa (Hochst.ex A. Richmond) harms (family fabaceae)

Abstract

This study is on the quantitative determination of phytochemical composition in tubers of 17 accessions of the African Yam Bean (AYB), Sphenostylis stenocarpa (Hochst.ex A. Richmond) Harms. Standard laboratory methods were followed to ascertain the presence and quantity of some phytochemicals in the tubers of the 17 AYB accessions. The result showed that variations existed among the studied accessions for the eleven phytochemical constituents. The ranges were: total alkaloid (22.195-183g\100g), Glycosides (4.338- 14.733g\100), Flavonoids (7.732- 14.037g/100), Phenols (16.448-32.287g/100), Oxalate (2.519-8.938ppm), Tannin (1.22- 4.340ppm), Saponin (1.475-5.232ppm), Hydrogen Cyanide (0.261-0.928ppm), Phytate (1.532- 5.435ppm), Trypsin Inhibitor (1.088-3.858ppm), and Organic Acid (11.537-23.904ppm). A high significant correlation was observed among the first three principal component axes which accounted for 90.4% of the total variation among the accessions. The cluster analysis showed the existence of two significant divergent groups. The accessions in cluster II recorded the least values for oxalate, tannins, saponins, hydrogen cyanide, phytate, trypsin inhibitor, glycoside, flavonoid and phenols while cluster I had higher values for them. The identified phytochemicals with the significant intra-specific variations seem to provide clues which underscores the possibilities of selection and improvement of these tubers for food and medicine for humans.