Screening of ligands for carbonic anhydrase II from traditional Chinese medicine Kansui by combination of in silico target prediction, surface plasmon resonance, and UPLC-HR-MS/MS.

Screening of ligands from natural products, especially traditional herbs, has always been an important pathway for drug discovery. In the current work, we present a strategy for the screening of active substances from TCM by combination of in silico target prediction, surface plasmon resonance (SPR), and UPLC-HR-MS/MS, using Kansui as an illustration. In the first, in silico target prediction of diterpenoids from Kansui was performed, aiming to improve the success rate of screening. Carbonic anhydrase II (CA II) were within the most likely targets. Then, SPR combined with UPLC-HR-MS/MS analysis was employed for the screening of ligands for CA II from a mixture of Kansui extract and for the structural identification of the captured ingredients. It was found that the ligands of CA II are mainly ingenane-type diterpenoids, which was further validated by enzymatic activity experiments and molecular docking that ingenane-type diterpenoids have more affinity and potency for CA II activation. It is the first time that the ligands of CA II have been screened from the extract of Kansui, and the present ligand screening work also providing clues to the pharmacological mechanisms and rationality of vinegar-processed Kansui.