Structure–Activity Relationship and Neuroprotective Activity of 1,5-Dihydro-2<i>H</i>-naphtho[1,2-<i>b</i>][1,4]diazepine-2,4(3<i>H</i>)-diones as P2X4 Receptor Antagonists
Kiran S. Toti, Rajkumar Verma, Michael J. McGonnigle, Daylín Gamiotea Turro, Zhiwei Wen, Sarah A. Lewicki, Bruce T. Liang, Kenneth A. Jacobson
Abstract
We analyzed the P2X4 receptor structure–activity relationship of a known antagonist 5, a 1,5-dihydro-2H-naphtho[1,2-b][1,4]diazepine-2,4(3H)-dione. Following extensive modification of the reported synthetic route, 4-pyridyl 21u (MRS4719) and 6-methyl 22c (MRS4596) analogues were most potent at human (h) P2X4R (IC50 0.503 and 1.38 μM, respectively, and selective versus hP2X1R, hP2X2/3R, hP2X3R). Thus, the naphthalene 6-, but not 7-position was amenable to substitution, and an N-phenyl ring aza-scan identified 21u with 3-fold higher activity than 5. Compounds 21u and 22c showed neuroprotective and learning- and memory-enhancing activities in a mouse middle cerebral artery occlusion (MCAO) model of ischemic stroke, with potency of 21u > 22c. 21u dose-dependently reduced infarct volume and reduced brain atrophy at 3 and 35 days post-stroke, respectively. Relevant to clinical implication, 21u also reduced ATP-induced [Ca2+]i influx in primary human monocyte-derived macrophages. This study indicates the translational potential of P2X4R antagonists for treating ischemic stroke, including in aging populations.