Identification and characterization of chemical constituents in Mahuang Guizhi Decoction and their metabolites in rat plasma and brain by UPLC-Q-TOF/MS

Mahuang Guizhi Decoction (MGD), an essential herbal pair in traditional Chinese medicine, is able to release cold, fever and asthma, mainly containing alkaloids, flavonoids, phenylpropanoids and amino acids. However, the absorption and distribution of these four category compounds