Chemical Characterization, Antioxidant Activity and Cytotoxicity of the Unconventional Food Plants: Sweet Potato (Ipomoea batatas (L.) Lam.) Leaf, Major Gomes (Talinum paniculatum (Jacq.) Gaertn.) and Caruru (Amaranthus deflexus L.)

Unconventional food plants (UFPs), many of them popularly known as "weeds", are edible species with nutritional and socioeconomic potential that need to be rescued from intensive farming. The aims of this study were: to accomplish an ethnobotanical survey of UFPs consumed on Mem de Sa Island, Sergipe, Brazil and then to characterize the three most commonly used UFPs. The physicochemical parameters and bioactive compounds were assessed, and the in vitro antioxidant activity of the aqueous extracts of the plants was evaluated using DPPH radical assay, ABTS radical cation, and the β-carotene/linoleic acid cooxidation method. The cytotoxicity of the compounds was also analyzed using MTT assay in L929 fibroblasts. The survey identified 31 species of UFPs distributed in 22 families, and revealed that knowledge about the plants was concentrated in older individuals. The three most commonly used were Talinum paniculatum (Jacq.) Gaertn. (29.03%), Ipomoea batatas (L.) Lam. (purple and white) leaf (25.81%) and Amaranthus deflexus L. (16.13%). Ipomoea batatas (L.) Lam. had the highest total carbohydrate content, the purple variety the highest protein and total carotenoids content, and the white variety the highest copper (Cu), while its aqueous extract had the highest phenolic compounds and total flavonoids; Talinum paniculatum (Jacq.) Gaertn. had the highest iron (Fe) content, and, with Amaranthus deflexus L., the highest calcium (Ca); and Amaranthus deflexus L. had the highest vitamin C. The extracts of the analyzed plants showed antioxidant potential. Therefore, these UFPs are alternative nutritional sources for food diversification in modern society.