Design and synthesis of adamantane-1-carbonyl thiourea derivatives as potent and selective inhibitors of h-P2X4 and h-P2X7 receptors: An Emerging therapeutic tool for treatment of inflammation and neurological disorders

P2X receptors are potential therapeutic targets for the treatment of various neurodegenerative disorders, pain, inflammation, hypertension, and cancer. Adamantane ring has been reported to exhibit significant inhibitory potential towards P2X receptors, especially for P2X7R. We have utilized uniqueness of adamantane moiety in our synthesized compounds and introduced various substitutions that enhanced the potency as well as selectivity for P2XR subtypes. Among synthesized derivatives, 4n and 5b were found to be most potent and selective inhibitors for h-P2X4R and h-P2X7R, respectively. 4n was found to be highly selective for h-P2X4R with IC₅₀ ± SEM = 0.04 ± 0.01 μM, that is 22 times more potent than BX-430, a standard selective inhibitor of h-P2X4R. 5b has IC₅₀ ± SEM of 0.073 ± 0.04 μM, which is comparable with the known antagonists of h-P2X7R. 4n and 5b were studied for mode of inhibition of P2XRs and both were found to be negative allosteric modulators. In silico studies were also conducted to find the type of interactions as well as mode of inhibition.