Phenolic compounds as potential adenosine deaminase inhibitors

Abstract

Adenosine deaminase (ADA) is a Zn2+-containing enzyme that catalyzes the irreversible deamination of adenosine to inosine or deoxyadenosine to deoxyinosine. In addition to this enzymatic function, ADA mediates cell-to-cell interactions involved in lymphocyte co-stimulation or endothelial activation. ADA is implicated in cardiovascular pathologies such as atherosclerosis and certain types of cancers, including lymphoma and leukemia. To date, only two drugs (pentostatin and cladribine) have been approved for the treatment of hairy cell leukemia. In search of natural ADA inhibitors, we demonstrated the binding of selected phenolic compounds to the active site of ADA using molecular docking and molecular dynamics simulation. Our results show that phenolic compounds (chlorogenic acid, quercetin, and hyperoside) stabilized the ADA complex by forming persistent interactions with the catalytically essential Zn2+ ion. Furthermore, MM-GBSA ligand binding affinity calculations revealed that hyperoside had a comparable binding energy score (& UDelta;G = - 46.56 & PLUSMN; 8.26 kcal/mol) to that of the cocrystal ligand in the ADA crystal structure (PDB ID: 1O5R) (& UDelta;G = - 51.97 & PLUSMN; 4.70 kcal/mol). Similarly, chlorogenic acid exhibited a binding energy score (& UDelta;G = - 18.76 & PLUSMN; 4.60 kcal/mol) comparable to those of the two approved ADA inhibitor drugs pentostatin (& UDelta;G = - 14.54 & PLUSMN; 2.25 kcal/mol) and cladribine (& UDelta;G = - 25.52 & PLUSMN; 4.10 kcal/mol) while quercetin was found to have modest binding affinity (& UDelta;G = - 8.85 & PLUSMN; 7.32 kcal/mol). This study provides insights into the possible inhibitory potential of these phenolic compounds against ADA.