Bioactive compounds of Shuang-Huang-Lian prescription and an insight into its binding mechanism by β2 -adrenoceptor chromatography coupled with site-directed molecular docking.

Owing to the promising clinical efficacy and relatively simple composition, Shuang-Huang-Lian prescription is widely prescribed for the treatment of acute upper respiratory tract infection and acute bronchitis in practice. This necessitates the understanding of the bioactive compounds of the prescription and their binding mechanism to β2 -adrenoceptor, which mediates the aforementioned ailments. In this work, a column containing immobilized β2 -adrenoceptor was prepared using a diazonium salt reaction. The bioactive compound collected from the β2 -adrenoceptor column was identified as chlorogenic acid by using high-performance liquid chromatography coupled with ion trap mass spectrometry. Using an injection amount dependent method, chlorogenic acid proved the binding to β2 -adrenoceptor through two kinds of sites. The numbers of the sites were (1.42 ± 0.03) × 10-8 and (9.06 ± 0.49) × 10-8  M. The association constants were (2.72 ± 0.01) × 105 and (2.80 ± 0.01) × 104  M-1 , respectively. Molecular docking analysis of the interaction between chlorogenic acid and β2 -adrenoceptor indicated that the binding mainly occurred on Ser169 , Ser173 , and Phe287 of β2 -adrenoceptor. These results paved the way to screen bioactive compounds of other traditional medicines by receptor chromatography.