Determination of Dietary Toxins in Selected Wild Edible Plants of Ethiopia

Abstract

Despite the great role of wild edible plants (WEPs) in ensuring food security and the fact that they can serve as a source of income, the consumption and acceptance varies from place to place. Although social, economic and cultural factors might have contributed for the avoidance of some edible wild plants, the fear of presence of toxic principles including heavy metals or their counter ions and antinutritional components might also be a barrier to the use of WEPs. In this study, the determination of the levels of some selected heavy metals (Cu, Cr, Ni, Cd and Pb) and antinutritional (oxalate) components are carried out using Flame Atomic Absorption Spectrophotometry and HPLC methods. The results showed that the mean metal concentration (mg/kg) in ripe fruit of WEP, unripe fruit of WEP and their underlying soil samples were 4.57, 5.77 and 3.22 (Cu), 2.37, 1.54, and 3.54 (Pb), 0.93, 0.63, and 0.42 (Cd), 2.02, 2.09, and 2.24 (Ni) and 2.47, 2.09, and 2.24 (Cr) respectively.The amounts of oxalate (mg/kg) in WEPs (Ripe Dovyalis Abyssinica, Unripe Dovyalis Abyssinica Unripe Ficus Sur Forresk and Unripe Blackberry) were 359.93, 301.01, 815.08 and 1406.15 mg/Kg respectively. All the heavy metals considered in this study and oxalate contents were detected in both WEPs and their underlying soil samples. The highest concentration of the heavy metals was found in blackberry while the lowest in unripe strawberry. Using one way ANOVA, significant (P = 0.05) variations among the levels of heavy metals in ripe and unripe were recorded. Generally, the content of heavy metals was higher in most of WEPs than their underlying soils. In conclusion, on the basis of the level of heavy metals and oxalate content, blackberry is found to be less safe for consumption than other WEPs considered in this study.

Keywords: Wild edible plants, heavy metals, anti-nutritional factors, oxalate, HPLC.