Taraxacum officinale has been widely used as a folkloric medicine for the treatment of diverse diseases. The dried plant was extracted with 70% ethanol to generate its ethanol extract (TEE). For some experiments, ethyl acetate (EA), n-butanol (BuOH) and aqueous (Aq) fractions were prepared in succession from TEE. TEE showed a scavenging activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, a diminishing effect on intracellular reactive oxygen species (ROS) level, and an anti-angiogenic activity in the chicken chorioallantoic (CAM) assay. In the carrageenan-induced air pouch model, TEE inhibited production of exudate, and significantly diminished nitric oxide (NO) and leukocyte levels in the exudate. It also possessed an inhibitory effect on acetic acid-induced vascular permeability and caused a dose-dependent inhibition on acetic acid-induced abdominal writhing in mice. Suppressive effects of TEE on the production of NO and expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-stimulated macrophages were also assessed. Among the fractions, the n-butanol fraction (BuOH) was identified to be most effective in the CAM assay. Collectively, Taraxacum officinale contains anti-angiogenic, anti-inflammatory and anti-nociceptive activities through its inhibition of NO production and COX-2 expression and/or its antioxidative activity.

Flavonoids and coumaric acid derivatives were identified from dandelion flower (Taraxacum officinale). Characteristics of chain-breaking antioxidants, such as extended lag phase and reduced propagation rate, were observed in oxidation of linoleic acid emulsion with the addition of dandelion flower extract (DFE). DFE suppressed both superoxide and hydroxyl radical, while the latter was further distinguished by both site-specific and non-specific hydroxyl radical inhibition. DPPH-radical-scavenging activity and a synergistic effect with alpha-tocopherol were attributed to the reducing activity derived from phenolic content of DFE. A significant (p < 0.05) and concentration-dependent, reduced nitric oxide production from acterial-lipopolysaccharide-stimulated mouse macrophage RAW264.7 cells was observed with the addition of DFE. Moreover, peroxyl-radical-induced intracellular oxidation of RAW264.7 cells was inhibited significantly (p < 0.05) by the addition of DFE over a range of concentrations. These results showed that the DFE possessed marked antioxidant activity in both biological and chemical models. Furthermore, the efficacy of DFE in inhibiting both reactive oxygen species and nitric oxide were attributed to its phenolic content.