Comprehensive quality evaluation of Scutellaria baicalensis Georgi by determination of multi-component content

A model for quality evaluation was developed by determination of multi-index components in Scutellaria baicalensis Georgi. Eight flavonoids in Scutellaria baicalensis Georgi were quantified by high performance liquid chromatography (HPLC), and a quantitative analysis of multi-components with a single marker (QAMS) method with baicalin as the internal reference substance was established. The 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS⁺) method was applied to determine the antioxidant activity of different batches of Scutellaria baicalensis Georgi. Grey relevance analysis was conducted to calculate the grey correlation coefficients of each antioxidant in the herb. The holistic quality of 75 batches of collected samples from different product regions was evaluated to distinguish different commercial types of Scutellaria baicalensis Georgi. The relative correction factor (RCF) of each index component with baicalin as the internal reference indicated good applicability, and there was no significant difference in assay results between the QAMS method and the external standard method (ESM). The results of grey correlation analysis showed that the content of eight index components including baicalin correlated strongly with the antioxidant activity of Scutellaria baicalensis Georgi. The calculated grey relational coefficient ranged from 0.772 4 to 0.808 6. The content of oroxylin A-7-O-β-D-glucuronide, norwogonin-7-O-β-D-glucuronide, baicalein, wogonin and oroxylin A showed positive correlations with the antioxidant potency. In contrast, baicalin, wogonoside and viscidulin III content exhibited negative correlations. The ratio of the flavonoid glycosides and flavonoid glycoside aglycones were found to be a critical factor to distinguish the different types of commercial herbs. The crude herbs could be characterized as Scutellaria baicalensis pith-decayed with a G/A ratio less than 10, and the ratio in Scutellaria baicalensis pith-not decayed should be more than 10. The QAMS method established in this study is simple and accurate, and can be used for the determination of eight flavonoids in Scutellaria baicalensis Georgi. Combined with ABTS⁺ antioxidant activity and grey correlation analysis, a comprehensive model for Scutellaria baicalensis Georgi quality determination based on biological activity was established, which provides new ideas and methods for the establishment of quality standards consistent with the characteristics of traditional Chinese medicine.