Antioxidant and Prebiotic Activity of Selected Edible Wild Plant Extracts

Edible wild plants were investigated as potential sources of antioxidants and prebiotics to benefit human health. Antioxidant activity, ascorbic acid and total dietary fibre contents were determined in edible wild plants from Lesotho, Swaziland and South Africa. Pure probiotic strains of Bifidobacterium animalis subsp. animalis (ATCC 25527), Lactobacillus rhamnosus (TUTBFD) and Lactobacillus acidophilus (ATCC 314) were cultured in broth containing edible wild plant extracts to assess their prebiotic activity. Cyperus esculantus had the highest arscobic acid content of 603±64.1 mg/100 g edible dry plant material followed by Rosa rubiginosa (500.8±48.8 mg/100 g). The two plants had IC50 of 10.7±0.2 µg/mL and 47.8±0.2 µg/mL for DPPH inhibition, respectively. Forty percent (40%) (n=30) of the edible wild plants had significant (p<0.01) total antioxidant activity (IC50<60 µg/mL) and high ascorbic acid content (>200 mg/100 g). Nasturtium officinale reported the highest yield for soluble fibre (25%) while Hypoxis hirsute had the highest total dietary fibre content (7.3%). Rorippa nudiuscula enhanced the growth of B. animalis significantly (p=0.001), 8-fold more than inulin. Chenopodium album and Urtica dioica stimulated the growth of L. rhamnosus significantly (p=0.0001) than inulin, respectfully, while Tragopogon porrifolius significantly (p=0.0001) stimulated the growth of L. acidophilus than inulin. It was concluded that the investigated edible wild plants from southern Africa have antioxidant and prebiotic properties that may be beneficial to human health.