Antioxidant activity of Taraxacum officinale

Abstract

Introduction. Taraxacum officinale, considered a weed in many crops around the world, is regarded as a fully nontoxic and entirely edible plant. The chemical composition of plant (flowers, leaves, roots and latex) has been studied extensively due to its biological actions: antioxidant, anti-inflammatory, anti-carcinogenic, anti-hyperglycaemic, anti-thrombotic, antimicrobial and antiviral. Aim of the study. To establish the optimal conditions for the extraction of the bioactive compounds from the Taraxacum officinale leaves and their characterization (study of the physical-chemical and biological properties). Materials and methods. The process of extraction from the investigated vegetal material has been realized by using the maceration during 24 hours. The extraction has been realized at a room temperature in three consecutive steps for each method using as a solvents: 80%, 50%, and 20% of ethanol. The antioxidant properties of the obtained extracts was investigated by the ABTS (2,2-azinobis-(3-ethylbenzothiazoline)-6-sulfonic acid) method described by Re et al., with some modifications. The results were expressed as percent inhibition of the ABTS radical. Trolox (6-hydroxy-2,5,7,8-tetramethychroman-2-carboxylic acid) and Rutin (Quercetin-3- rutinoside hydrate; Sigma-Aldrich) was used as antioxidant standard. Results. The highest antioxidant properties in the leaves of Taraxacum officinale showed the extraction with 80% EtOH, at concentrations of 1.25, 0.63 and 0.31 μg/ml, the inhibition percentage in the ABTS test was: 93%, 77% and 48%, respectively. The lower inhibition activity was observed with 50% EtOH extract at concentrations of 4.69, 2.34 and 1.17 μg/ml, the inhibition rate was 95%, 94% and 94%. A similar ABTS radical inhibition activity also showed the 20% EtOH extracts, which at concentrations of 4.38, 2.19 and 1.1 μg/ml, showed an inhibition rate of 95%, 94% and, respectively, 81%. The biologically active compounds extracted from the leaves of Taraxacum officinale more effectively capture the ABTS radical compared to the reference substances - Trolox and Rutin. Thus, Trolox and Rutin at concentrations of 187.5, 93.75 and 46.9 μg/ml, showed an inhibition rate in the ABTS test equal to 40%, 20%, 13% and, respectively, 40%, 24% and 17%. The biologically active compounds present in the leaves of Taraxacum officinale can act as free radical capture agents, thus participating in the prevention of DNA adduct formation and in the prevention of mutagenesis and carcinogenesis and may also exert chemopreventive effects. Conclusions. In this research, we developed an environmentally sustainable procedure for determining the antioxidant properties of Taraxacum officinale leaf extracts. We applied this procedure to select the most efficient method for extracting bioactive molecules with the highest antioxidant activity in the ABTS free radical capture assay. This method is fast, nontoxic, low cost and environmentally sustainable and due to its efficiency, it can be used in various biomedical applications.