Indolyl aryl Sulfones (IASs): Development of highly potent NNRTIs active against wt-HIV-1 and clinically relevant drug resistant mutants

Indolyl aryl sulfones (IASs) are a potent class of NNRTIs developed from L-737,126, a lead agent discovered by Merck AG. IAS derivatives are endowed with inhibitory activities against wt HIV-1 in the low nanomolar concentration range. Introduction of two methyl groups at positions 3 and 5 of the phenyl ring of the aryl sulfonyl moiety furnished IAS derivatives such as 5-chloro- or 5-bromo-3-[(3,5-dimethylphenyl)sulfonyl]indole-2-carboxyamide, which showed very potent and selective anti-HIV-1 activity against some mutants carrying NNRTI resistant mutations at positions 103 and 181 of the reverse transcriptase. IAS derivatives bearing 2-hydroxyethylcarboxyamide or 2- hydroxyethylcarboxyhydrazide groups at position 2 of the indole nucleus were more active than L-737,126 against the K103N-Y181C double mutant. A great improvement of antiviral activity against wt HIV-1 and resistant mutants was obtained by coupling 1-3 simple amino acids, such as glycine and alanine, in sequence, with the 3-[(3,5- dimethylphenyl)sulfonyl]-1H-indole-2-carbonyl moiety. The transformation of the chain terminus into amide or hydrazide, produced short peptides with high selectivity and potent activity against wt HIV-1, and the viral mutants Y181C, K103N-Y181C and EFVR. IAS having two halogen atoms at the indole showed potent inhibitory activity against the Y181C and the EFVR resistant mutant strains. In particular, the introduction of a fluorine atom at position 4 of the indole ring notably contributed to improve the antiviral activities against both wt and the related resistant mutants. 5- Nitro-IASs were highly active against wt HIV-1 and exhibited low cytotoxicity. Experimental data highlighted the class IAS derivatives as promising candidates for clinical trials.