Determination of Antioxidants and Total Phenolic Content in Some Wild Vegetables Used Widely in Lesotho

Abstract

Antioxidants, important chemicals that combat uncontrollable oxidation processes in the living cells, occur naturally in plants in the form of phenolic compounds such as phenolic acids and flavanoids. The total antioxidant capacity and total phenolic content of different wild edible plants consumed widely in Lesotho as vegetables, namely Moetse-oa-pere -Tragopogon dubius (Scopoli), Papasane -Rorippa nudiuscula, Leharasoana - Sonchus oleraceus (Linnaeus), Bobatsi - Urtica urens (Linnaeus) and Seruoe - Chenopodium album (Linnaeus) were determined from the ethanol extracts resulting in the linoleic acid peroxidation inhibition of 73.7%, 64.6%, 76.3%, 69.5% and 60.3% respectively using the iron (II) thiocyanate spectrophotometric method. The results also demonstrated high levels of total phenolic content (39.2–54.4 [MG1] mg GAE per gram of sample) with a significant correlation (R2=0.9277) between antioxidant capacity and total phenolic content. The extraction efficiency demonstrated temperature dependence as showed by the levelling off at around 80°C with some slight drop at boiling temperature of water (96°C). The observed abundance of the antioxidant capacity in these plants is gratifying considering how widely these vegetables are consumed in the rural areas of Lesotho – a small mountainous country in the Southern Africa.