Health Promoting Potentials of Selected South African Indigenous Leafy Vegetables

Six dietary leafy vegetables commonly consumed by the rural Eastern Cape communities of South Africa were analysed for their antioxidant activity and phenolic content. The indigenous leafy vegetables (ILVs) were Amaranthus hybridus, Solanum nigram, Bidens pilosa, Urtica urens, Ribes uva crispa and Taraxacum officianale. Aqueous and methanol extracts were tested for free radical scavenging and antioxidant activity using 2,2 azinobis-(3-ethylbenzthiazoline-6-sulphonic acid (ABTS) assay and expressed as trolox equvivalents. Total phenolic content was determined using the Folin-Ciocalteu assay with gallic acid as the standard and expressed as gallic acid equivalents. The antioxidant activity of the indigenous leafy vegetables for aqueous extracts ranged from 1.28 – 11.45 mmol/100g and the range observed for methanol extracts were 7.85 – 17.2 mmol/100g). The total phenolic content of the water extracts were 226.7 – 651.7mg/100g. The phenol content in the methanol extracts were in the range of 187.8 – 764.9 mg/100g gallic acid equivalent (GAE)/100g. Total antioxidant activity correlated well with total phenolic content of the methanol extract (R 2 – 0.875). Results suggest that the indigenous leafy vegetables tested in the study have the potential to provide antioxidant properties and may offer effective protection from free radical injury implicated in metabolic stress, chronic and degenerative diseases if included in the diet.