Biologically Active Substances and in Vitro Antioxidant Activity of Different Extracts from Dandelion (taraxacum Officinale) Roots

Dandelion (Taraxacum officinale L. Weber ex F.H. Wigg.) roots were traditionally used in folk medicine worldwide due to its antidiabetic, choleretic, antirheumatic and diuretic properties. The aim of the current study was to determinate the biologically active substances in 95% ethanol and subsequent water extracts from dandelion roots and to evaluate their antioxidant activities. The carbohydrate composition was analyzed by the resorcinol assay, TLC and HPLC-RID methods. The total phenolic contents (TPC), total flavonoids (TF) and total dihydroxycinnamic derivatives contents were determined by Folin–Ciocalteau method, aluminium chloride colorimetric assay and Arnow’s reagent, respectively. In vitro antioxidant activities of the extracts were estimated using ferric-reducing/antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assays. In spring harvested dandelion roots the total fructan content were established to be in range 17-19 % dw. The low molecular carbohydrate fraction presented by glucose, fructose, sucrose, 1-kestose and nystose dominated in 95 % ethanol extracts. The subsequent water extracts demonstrated the highest inulin content (12% dw), while TPC, TF and total dihydroxycinnamic derivatives contents were reported to be 9.2 mg GAE/g, 1.7 mg QE/g and 13.7 mg chlorogenic acid derivates/g dw, respectively. These extracts showed the highest antioxidant activity for both the DPPH (82.1 mM TE/g) and FRAP (52.9 mg mM TE/g) assays. Therefore, the subsequent water extracts possessed the highest antioxidant capacity, which positively correlated with the phenolic content. The results of current investigation demonstrate that dandelion root is a valuable source of dietary fibers and natural antioxidants and could be successfully used in foods with the potential to improve digestion and prevent from oxidative stress related diseases.