Five landraces of Smallanthus sonchifolius [(Poepp. and Endl.) H. Robinson], known as yacon, were investigated in total phenolic content, antioxidant activity and chemical composition of ethanol extracts (EEs) and decoction extracts (DEs). The results demonstrated that DEs are rich in phenolic acids as caffeic acid, while the EEs show an higher amount of flavonoids, as luteolin 3',7-O-diglucoside and luteolin 7-O-glucoside. These flavonoid glycosides were identified for the first time in yacon extracts, together with apigenin and luteolin. The phytochemical profile explains the different antioxidant activities shown in our study. The landraces PER6-DE and PER4-DE showed the highest radical-scavenging activity and reducing power related to their polyphenolic contents. Results also show that yacon can be considered an important source of bioactive compounds with significant differences among the analysed landraces.
Keywords: flavonoid glycoside; phenolic acid; plant extract; yacon.