Therapeutic Path to Double Knockout: Investigating the Selective Dual-Inhibitory Mechanisms of Adenosine Receptors A1 and A2 by a Novel Methoxy-Substituted Benzofuran Derivative in the Treatment of Parkinson's Disease.

The dual inhibition of adenosine receptors A1 (A1 AR) and A2 (A2A AR) has been considered as an efficient strategy in the treatment of Parkinson's disease (PD). This led to the recent development of a series of methoxy-substituted benzofuran derivatives among which compound 3j exhibited dual-inhibitory potencies in the micromolar range. Therefore, in this study, we seek to resolve the mechanisms by which this novel compound elicits its selective dual targeting against A1 AR and A2A AR. Unique to the binding of 3j in both proteins, from our findings, is the ring-ring interaction elicited by A1Phe275 (→ A2Phe170) with the benzofuran ring of the compound. As observed, this π-stacking interaction contributes notably to the stability of 3j at the active sites of A1 and A2A AR. Besides, conserved active site residues in the proteins such as A1Ala170 (→ A2Ala65), A1Ile173 (→ A2Ile68), A1Val191 (→ A2Val86), A1Leu192 (→ A2Leu87), A1Ala195 (→ A2Ala90), A1Met284 (→ A2Met179), A1Tyr375 (→ A2Tyr369), A1Ile378 (→ A2Ile372), and A1His382 (→ A2His376) were commonly involved with other ring substituents which further complement the dual binding and stability of 3j. This reflects a similar interaction mechanism that involved aromatic (π) interactions. Consequentially, vdW energies contributed immensely to the dual binding of the compound, which culminated in high ΔGbinds that were homogenous in both proteins. Furthermore, 3j commonly disrupted the stable and compact conformation of A1 and A2A AR, coupled with their active sites where Cα deviations were relatively high. Ligand mobility analysis also revealed that both compounds exhibited a similar motion pattern at the active site of the proteins relative to their optimal dual binding. We believe that findings from this study with significantly aid the structure-based design of highly selective dual-inhibitors of A1 and A2A AR.