Screening of Quality Control Components in Xiaoer Caige Tuire Oral Liquid Based on Multicomponent Absorption and Sequential Metabolism

Background: Xiaoer Chaige Tuire Oral Liquid (XCT) is a compound preparation composed of 7 traditional Chinese medicines including Bupleuri Radix, Puerariae Lobatae Radix, Scutellariae Radix, Gypsum Fibrosum, Artemisiae Annuae Herba, Paeoniae Radix Alba and Zhigancao in proportion. It is mainly aimed at treating upper respiratory tract infection in children caused by exogenous wind-heat. Modern pharmacological studies have indicated that XCT has a variety of activities such as antibacterial, anti-inflammatory, antiviral and immune regulation.<br><br>Purpose: To analyze the oral administration metabolism process of XCT by means of sequential metabolism in vitro and verification experiment in vivo, and to screen potential quality control components of XCT.<br><br>Methods: The main components of prepared XCT were analyzed by high performance liquid chromatography with diode-array detection (HPLC-DAD). The employed models in vitro of XCT sequential metabolism were artificial gastric fluid, artificial intestinal fluid, intestinal bacteria, Caco-2 cells and liver S9 in order. The quantitative analysis of sequential metabolism samples were also analyzed by HPLC-DAD. Ultra performance liquid chromatography QExactive Orbitrap tandem mass spectrometry (LC-QExactive-HF-x-Orbitrap-MS) was used to determine the components in medicated plasma and metabolites in liver S9 of rats after applying XCT orally.<br><br>Results: A total of 25 components were identified from XCT, of which 19 with high content. Sequential metabolism studies in vitro indicated that baicalin, baicalein, genistin and saikosaponin A were digested in artificial gastric fluid. Albiflorin, glycyrrhizic acid, gallic acid and baicalein were unstable in artificial intestinal fluid. Daidzin, liquiritin and genistin were severally hydrolyzed into daidzein, liquiritigenin and genistein by intestinal bacteria. In addition, there were 7 well absorbed components were detected in the samples of Caco-2 cell model. After incubated by liver S9 system, 7 metabolites which were mainly the products of hydroxylation and glycosylation were identified. A total of 10 components were determined in the drug-containing plasma of rats, among which daidzein, puerarin and benzoic acid were the common components both in absorption model samples and the plasma samples.<br><br>Conclusions: A sequential metabolism methodology of XCT in vitro and in vivo was established. Puerarin, daidzein, benzoic acid, baicalin, baicalein, wogonin, wogonoside, oroxylin A, 3′-methoxypuerarin, paeoniflorin, scopoletin and liquiritigenin were screened to be potential quality control components of XCT, which provides a material basis for quality control standard and redevelopment of XCT.