Computational Evaluation of 2-Phenyl-4H-chromen-4-one Analogues as Antihistamines: Potential Histamine N-Methyltransferase (HMT) Inhibitors

Abstract

Abnormal release of histamine, which is present in relatively high concentration in the lungs, causes serious allergic vasoconstriction and anaphylactic manifestation in human beings. In mammals, a major pathway of histamine metabolism in the lungs is mediated by histamine N-methyl transferase (HMT) and diamine oxidase. The need to design a strategy of mechanistic computational evaluation of protein-ligand affinity i.e. HMT- 2-phenyl-4H-chromen-4-ones, protein complex binding energy has been established. A library of synthesized 2-phenyl-4H-chromen-4-ones was docked into the active site cavity of target protein, HMT (Pdb: 2aot). The high-resolution crystal structure of HMT complex with the competitive inhibitor N [2 (benzhydryloxy)ethyl] N N-Dimethylamine (Diphenhydramine) revealed a protein with a highly confined binding region that could be targeted in the design of specific anti-histamines. The validation of docking programme by Potential Mean Force was compared with binding energy results of known ligands in the active sites of HMT, diphenhydramine / benadryl, promethazine, cyproheptadine, trimeton / avil etc. All the synthesized chromone derivatives showed comparable negative binding energies pointing towards the fact that these molecules could be potent antihistamines.