Fragment Addition-Based Design of Heteroaromatic-Biphenyl-DAPYs as Potent and Orally Available Non-nucleoside Reverse Transcriptase Inhibitors Featuring Significantly Enhanced Safety

Our previously disclosed biphenyl-DAPY <b>3</b> emerged as a potent inhibitor against WT HIV-1 and various mutant strains. Yet, its journey toward clinical application was thwarted by pronounced cytotoxicity and low selectivity (CC₅₀ = 6 μM, SI = 3515). The safety improvement approach we employed in this work entailed the incorporation of diverse heteroaromatic substituents at the C5 position to exploit the tolerant regions of the NNRTIs' binding pocket through fragment addition-based drug design strategy, ultimately leading to the identification of a series of novel heteroaromatic-biphenyl-DAPYs. The exemplary compound <b>10d</b> revealed a striking reduction in cytotoxicity (CC₅₀ > 272.81 μM), nearly 45.5 times lower than <b>3</b>, while showcasing 15-fold increase in selectivity (SI > 52632). This analog sustained exceptional anti-HIV-1 activity against both WT HIV-1 (EC₅₀ = 5 nM) and various mutant strains. Compared to <b>3</b>, a markedly slower rate of metabolism in human liver microsomes of <b>10d</b> was observed. Its pharmacokinetic profile was equally captivating, featuring excellent oral bioavailability (<i>F</i> = 57.4%). Moreover, <b>10d</b> exhibited a delicate sensitivity toward CYP, minimal inhibition of hERG, and no detectable acute toxicity in vivo. These enchanting findings illuminated the potential of <b>10d</b> as a promising candidate for HIV-1 therapy.