Profiling and identification of the metabolites of baicalin and study on their tissue distribution in rats by ultra-high-performance liquid chromatography with linear ion trap-Orbitrap mass spectrometer

Jiayu Zhang, Wei Caib, Yuan Zhou, Ying Liu, Xiaodan Wu, Yun Li, Jianqiu Lu , Yanjiang Qiao , 

Abstract

Baicalin (baicalein 7-O-glucuronide), which is one of the major bioactive constituents isolated from Scutellariae Radix, possesses many biological activities, such as antiallergic, antioxidation, and anti-inflammatory activities. In the present study, an efficient strategy was established using ultra-high-performance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometer (UPLC-LTQ-Orbitrap MS) to profile the in vivo metabolic fate of baicalin in rat plasma, urine, and various tissues. A combination of post-acquisition mining methods including extracted ion chromatogram (EIC) and multiple mass defect filters (MMDF) was adopted to identify the common and uncommon baicalin metabolites from the full mass scan data sets. Their structures were elucidated based on the accurate mass measurement, relevant drug biotransformation knowledge, the characteristic collision induced fragmentation pattern of baicalin metabolites, and bibliography data. Based on the proposed strategy, a total of 32 metabolites were observed and characterized. The corresponding reactions in vivo such

Authentic standards, viz.,baicalin, baicalein, scutellarin, wogonoside, and oroxin A, were purchased from Chengdu Biopurify Phytochemicals Ltd. (Chengdu, China).