Comparison of Bioactive Phenolic Compounds and Antioxidant Activities of Different Parts of Taraxacum mongolicum

Abstract

Herbs derived from Taraxacum genus have been used as traditional medicines and food supplements in China for hundreds of years. Taraxacum mongolicum is a famous traditional Chinese medicine derived from Taraxacum genus for the treatment of inflammatory disorders and viral infectious diseases. In the present study, the bioactive phenolic chemical profiles and antioxidant activities of flowers, leaves, and roots of Taraxacum mongolicum were investigated. Firstly, a high performance liquid chromatography method combined with segmental monitoring strategy was employed to simultaneously determine six bioactive phenolic compounds in Taraxacum mongolicum samples. Moreover, multivariate statistical analysis, including hierarchical clustering analysis, principal component analysis, and partial least squares discriminant analysis were performed to compare and discriminate different parts of Taraxacum mongolicum based on the quantitative data. The results showed that three phenolic compounds, caftaric acid, caffeic acid, and luteolin, could be regarded as chemical markers for the differences of flowers, leaves, and roots of Taraxacum mongolicum. In parallel, total phenolic contents, total flavonoid contents and antioxidant activities of different parts of Taraxacum mongolicum were also evaluated and compared. It is clear that Taraxacum mongolicum had antioxidant properties, and the antioxidant capacities of different parts of Taraxacum mongolicum in three antioxidant assays showed a similar tendency: Flowers ≈ leaves > roots, which revealed a positive relationship with their total phenolic and flavonoid contents. Furthermore, to find the potential antioxidant components of Taraxacum mongolicum, the latent relationships of the six bioactive phenolic compounds and antioxidant activities of Taraxacum mongolicum were investigated by Pearson correlation analysis. The results indicated caftaric acid and caffeic acid could be the potential antioxidant ingredients of Taraxacum mongolicum. The present work may facilitate better understanding of differences of bioactive phenolic constituents and antioxidant activities of different parts of Taraxacum mongolicum and provide useful information for utilization of this herbal medicine.

Keywords: Taraxacum mongolicum; antioxidant activity; multivariate statistical analysis; phenolics.

Figure 1

The typical high performance liquid chromatography (HPLC) chromatograms of flowers (a), leaves (b), roots (c) of Taraxacum mongolicum, and mixed standard solution (d). S1, caftaric acid; S2, chlorogenic acid; S3, caffeic acid; S4, cichoric acid; S5, 3,5-di-O-caffeoylquinic acid; S6, luteolin.

Figure 2

The dendrograms of hierarchical clustering analysis (HCA) (a), and the score plots of principal component analysis (PCA) (b) and partial least squares discriminant analysis (PLS-DA) (c). Green circles represent Taraxacum mongolicum flowers (F1–F12); blue squares represent Taraxacum mongolicum leaves (L1–L11); red triangles represent Taraxacum mongolicum roots (R1–R9).

Figure 3

Total flavonoid contents (a), total phenolic contents (b) DPPH (c), ABTS (d), and FRAP(e) assays of flowers (F), leaves (L), and roots (R) of Taraxacum mongolicum. (mean ± SEM, n = 3) * p < 0.05, ** p < 0.01, *** p < 0.001.

Figure 4

(a) Heatmap analysis of the Pearson correlation of the six phenolic compounds and antioxidant activities (ABTS, DPPH, FRAP). Red represents positive correlated and blue indicates negative correlated. (b) The IC50 values of antioxidant activity (DPPH) of six phenolic compounds. S1, caftaric acid; S2, chlorogenic acid; S3, caffeic acid; S4, cichoric acid; S5, 3,5-di-O-caffeoylquinic acid; S6, luteolin.

Figure 5

Chemical structures of the six phenolic compounds. S1, caftaric acid; S2, chlorogenic acid; S3, caffeic acid; S4, cichoric acid; S5, 3,5-di-O-caffeoylquinic acid; S6, luteolin.