Microplate-based assay for identifying small molecules that bind a specific intersubunit interface within the assembled HIV-1 capsid

Synthesis, Enantiomeric Resolution and Biological Evaluation of HIV Capsid Inhibition Activity for Racemic, (S)- and (R)-PF74

PF74 is a capsid-targeting inhibitor of HIV replication that effectively perturbs the highly sensitive viral uncoating process. A lack of information regarding the optical purity (enantiomeric excess) of the single stereogenic centre of PF74 has resulted in ambiguity as to the potency of different samples of this compound. Herein is described the synthesis of enantiomerically enriched (S)- and (R)-PF74 and further enrichment of the samples (≥98%) using chiral HPLC resolution. The biological activities of each enantiomer were then evaluated, which determined (S)-PF74 (IC₅₀ 1.5 µM) to be significantly more active than (R)-PF74 (IC₅₀ 19 µM). Computational docking studies were then conducted to rationalise this large discrepancy in activity, which indicated different binding conformations for each enantiomer. The binding energy of the conformation adopted by the more active (S)-PF74 (ΔG = -73.8 kcal/mol) was calculated to be more favourable than the conformation adopted by the less active (R)-enantiomer (ΔG = -55.8 kcal/mol) in agreement with experimental observations.

Carbazole Derivatives as Antiviral Agents: An Overview

Keywords: carbazole; tetrahydrocarbazole; antiviral agents.

Chloro-1,4-dimethyl-9H-carbazole Derivatives Displaying Anti-HIV Activity

BACKGROUND

Despite the progress achieved by anti-retroviral drug research in the last decades, the discovery of novel compounds endowed with selective antiviral activity and reduced side effects is still a necessity. At present, the most urgent requirement includes the improvement of HIV (Human Immunodeficiency Virus) prevention and sexual transmission and the development of new drugs to treat the chronic lifelong infection.

METHODS

Six chloro-1,4-dimethyl-9H-carbazoles (2a,b-4a,b) have been prepared following opportunely modified known chemical procedures and tested in luciferase and Escherichia coli β-galactosidase expressing CD4⁺, CXCR4⁺, CCR5⁺ TZM-bl cells.

RESULTS AND CONCLUSION

a preliminary biological investigation on the synthesized small series of chloro-1,4-dimethyl-9H-carbazoles has been carried out. Among all tested compounds, a nitro-derivative (3b) showed the most interesting profile representing a suitable lead for the development of novel anti-HIV drugs.