Synthesis and nNOS inhibitory activity of benzenealkyl isothiourea compounds

AimTo search for novel compounds with potent nNOS inhibitory activity for the treatment of Alzheimer′s disease. MethodsThe target compounds were obtained by introduing benzenealkyl groups into the structure of isothioureas. nNOS inhibitory activity assays were conducted for the target compounds. Results Sixteen benzenealkyl isothiourea compounds (I1-16) were synthesized by three different synthetic methods from benzylamine (1) or (substituted) phenethylamine (2). Compounds I1-6 were synthesized from 1 or 2 by reaction with benzoyl isothiocyanate to form the corresponding benzoylthioureas 3 or 4, followed by hydrolysis with 10% sodium hydroxide solution, then S-alkylation with methyl iodide or ethyl iodide. I7-14 were synthesized from 1 or 2 by reaction with methyl isothiocyanate to form the corresponding 1,3-disubstituted thioureas 7 or 8 which were S-alkylated with methyl iodide or ethyl iodide. I₁₅ and I₁₆ were synthesized from 2 by reaction with dimethyl cyanodithioimidocarbonate. The structures of compounds I1-16 were confirmed by MS, IR, ¹HNMR and elementary analysis. The results of preliminary pharmacological test showed that all compounds possessed nNOS inhibitory activity, among which compounds I₈, I₁₂ and I₁₄ had good activity. Conclusion Compounds I₈, I₁₂ and I₁₄ showed superior pharmacological profiles to the control compound S-methyl-N-(4-methoxyphenyl) isothiourea. The IC₅₀ values of compounds I₈, I₁₂ and I₁₄ inhibiting nNOS were 8.13×10-7 mol·L^-1, 1.74×10-7 mol·L^-1 and 2.23×10-7 mol·L^-1 respectively, and it is worth further studying.