Halogenation-Driven Discovery of Halomethylene-Biphenyl-Diarylpyrimidines as Potent HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitors with Improved Safety and PK Profiles

To improve the safety and PK profiles of our previously established (<i>S</i>)-<b>4a</b>, a series of halomethylene-linked biphenyl-DAPYs were developed. Enantioselectivity studies of the most promising <b>5m</b> suggested that the (<i>S</i>)-enantiomer was more potent than its (<i>R</i>)-counterpart and racemate. The optimal (<i>S</i>)-<b>5m</b> exhibited remarkable antiviral activity toward wild-type HIV-1 and single mutant strains (EC₅₀ = 3.7-231 nM). Notably, this compound possessed 32-fold lower cytotoxicity and a 13-fold higher selectivity index (CC₅₀ > 288 μM, SI > 78,125) than those of (<i>S</i>)-<b>4a</b>. In vitro metabolic stability assays demonstrated that (<i>S</i>)-<b>5m</b> had good stability in human plasma and human liver microsomes. Besides, no apparent inhibition of CYP or hERG was observed. More importantly, (<i>S</i>)-<b>5m</b> was characterized by favorable in vivo safety properties (LD₅₀ > 2 g/kg) and significantly improved PK profiles (<i>F</i> = 49.5%, <i>T</i>_1/2 = 13.86 h). These findings provided insights for the design of novel NNRTIs for HIV treatment.