An appraisal of eighteen commonly consumed edible plants as functional food based on their antioxidant and starch hydrolase inhibitory activities

BACKGROUND: Eighteen edible plants were assessed for their antioxidant potential based on oxygen radical absorbance capacity (ORAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, total phenolics, vitamin C content and various lipophilic antioxidants. The inhibitory activities of the plant extracts against the enzymatic activities of α-amylase and α-glucosidase were also evaluated. RESULTS: The antioxidant and starch hydrolase activities of the plants varied widely across a single batch of analysis. The ORAC and DPPH radical scavenging EC₅₀ values varied between 298 and 1984 Trolox equivalents g^-1 fresh weight and between 91 and 533 mg kg^-1 fresh weight, respectively. The total phenolics and vitamin C contents varied between 32 and 125 mg gallic acid equivalents g^-1 fresh weight and between 96 and 285 μg g^-1 fresh weight, respectively. All the plants contained neoxanthin, violaxanthin, and α- and β- carotene in varying amounts. Coccinia grandis, Asparagus racemosus, Costus speciosus, Amaranthus viridis and Annona muricata displayed the highest inhibitory activities against starch hydrolases. They were the most efficient against the breakdown of seven starches exposed to the two enzymes as well. CONCLUSIONS: Overall, the edible plants were observed to display a high antioxidant potential with starch hydrolase inhibitory properties, which were beneficial in their being recognized as functional food.