Discovery of Novel Amino Acids (Analogues)-Substituted Thiophene[3,2-<i>d</i>]pyrimidine Derivatives as Potent HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitors: Design, Synthesis, and Biological Evaluation

Abstract

Inspired by our previous work on the modification of diarylpyrimidine-typed non-nucleoside reverse transcriptase inhibitors (NNRTIs) and the reported crystallographic studies, a series of novel amino acids (analogues)-substituted thiophene[3,2-d]pyrimidine derivatives were designed and synthesized by targeting the solvent-exposed region of the NNRTI-binding pocket. The biological evaluation results showed that compound 5k was the most active inhibitor, exhibiting moderate-to-excellent potency against HIV-1 wild-type (WT) and a panel of NNRTI-resistant strains, with EC50 values ranging from 0.042 μM to 7.530 μM. Of special note, 5k exhibited the most potent activity against single-mutant strains (K103N and E138K), with EC50 values of 0.031 μM and 0.094 μM, being about 4.3-fold superior to EFV (EC50 = 0.132 μM) and 1.9-fold superior to NVP (EC50 = 0.181 μM), respectively. In addition, 5k demonstrated lower cytotoxicity (CC50 = 27.9 μM) and higher selectivity index values. The HIV-1 reverse transcriptase (RT) inhibition assay was further performed to confirm their binding target. Moreover, preliminary structure–activity relationships (SARs) and molecular docking studies were also discussed in order to provide valuable insights for further structural optimizations. In summary, 5k turned out to be a promising NNRTI lead compound for further investigations of treatments for HIV-1 infections.

Keywords

• HIV-1
• NNRTIs
• thiophene[3,2-<i>d</i>]pyrimidine
• amino acids
• drug design