Antioxidant Sources from Leaves of Russian Dandelion

Taraxacum kok-saghyz (TKS) is a dandelion species native to Kazakhstan, Uzbekistan and north-west China, considered as a promising alternative source of natural rubber from its roots. The aim of this study was to investigate the possible exploitation of TKS leaves, a rubber byproduct, as a source of phenolic compounds with antioxidant properties for potential applications in forage, nutraceutical and pharmacological fields. Two accessions (TKS016, TKS018) grown under Mediterranean conditions of Sardinia were evaluated at vegetative and flowering stages. The leaves of TKS018 had the highest antioxidant capacity (19.6 mmol trolox equivalent antioxidant capacity 100 g^-1 ), total phenolic (106.4 g gallic acid equivalent kg^-1 ), tannic phenolics (58.5 g gallic acid equivalent kg^-1 ) and total flavonoid contents (22.9 g catechin equivalent kg^-1 ). At both phenological stages, TKS016 showed significantly lower values than TKS018 in 1,1-diphenyl-2-picrylhydrazyl (DPPH), total phenolic and tannic phenolics. Six individual molecules were identified, namely chlorogenic, cryptochlorogenic, caffeic, sinapic, chicoric and 3,4-dimethoxycinnamic acids. Chicoric (8.53-10.68 g kg^-1 DW) and chlorogenic acids (4.18-7.04 g kg^-1 DW) were the most abundant. TKS leaves represent a valuable source of chicoric acid with potential application as antioxidant to be used as herbal medicine and nutrition for production of healthy food/feed.