Studies towards the Design and Synthesis of Novel 1,5-Diaryl-1H-imidazole-4-carboxylic Acids and 1,5-Diaryl-1H-imidazole-4-carbohydrazides as Host LEDGF/p75 and HIV-1 Integrase Interaction Inhibitors

Two targeted sets of novel 1,5-diaryl-1H-imidazole-4-carboxylic acids 10 and carbohydrazides 11 were designed and synthesized from their corresponding ester intermediates 17, which were prepared via cycloaddition of ethyl isocyanoacetate 16 and diarylimidoyl chlorides 15. Evaluation of these new target scaffolds in the AlphaScreen^TM HIV-1 IN-LEDGF/p75 inhibition assay identified seventeen compounds exceeding the pre-defined 50% inhibitory threshold at 100 µM concentration. Further evaluation of these compounds in the HIV-1 IN strand transfer assay at 100 μM showed that none of the compounds (with the exception of 10a, 10l, and 11k, with marginal inhibitory percentages) were actively bound to the active site, indicating that they are selectively binding to the LEDGF/p75-binding pocket. In a cell-based HIV-1 antiviral assay, compounds 11a, 11b, 11g, and 11h exhibited moderate antiviral percentage inhibition of 33–45% with cytotoxicity (CC₅₀) values of >200 µM, 158.4 µM, >200 µM, and 50.4 µM, respectively. The antiviral inhibitory activity displayed by 11h was attributed to its toxicity. Upon further validation of their ability to induce multimerization in a Western blot gel assay, compounds 11a, 11b, and 11h appeared to increase higher-order forms of IN.