Discovery of second generation quinazolinone non-nucleoside reverse transcriptase inhibitors of HIV-1

Indolylarylsulfones, a fascinating story of highly potent human immunodeficiency virus type 1 non-nucleoside reverse transcriptase inhibitors

Indolylarylsulfones are a potent class of human immunodeficiency virus type 1 non-nucleoside reverse transcriptase inhibitors. In this review, the structure activity relationship (SAR) studies to improve the profile of sulfone L-737,126 discovered by Merck AG have been analysed with focus on introduction of the 3′,5′-dimethyl groups at the 3-phenylsulfonyl moiety, the 2-hydroxyethyl tail at the indole-2-carboxamide nitrogen, coupling of the carboxamide nitrogen with one or two glycinamide and alaninamide units, a fluorine atom at position 4 of the indole ring and correlation between configuration of the asymmetric centre and linker length. IAS derivatives look like promising drug candidates for the treatment of AIDS and related infections in combination with other antiretroviral agents.

Novel HIV-1 Non-nucleoside Reverse Transcriptase Inhibitors: A Combinatorial Approach

Highly active antiretroviral therapy (HAART) is one of the most effective means for fighting against HIV-infection. HAART primarily targets HIV-1 reverse transcriptase (RT), and 14 of 28 compounds approved by the FDA as anti-HIV drugs act on this enzyme. HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) hold a special place among HIV RT inhibitors owing to their high specificity and unique mode of action. Nonetheless, these drugs show a tendency to decrease their efficacy due to high HIV-1 variability and formation of resistant virus strains tolerant to clinically applied HIV NNRTIs. A combinatorial approach based on varying substituents within various fragments of the parent molecule that results in development of highly potent compounds is one of the approaches aimed at designing novel HIV NNRTIs. Generation of HIV NNRTIs based on pyrimidine derivatives explicitly exemplifies this approach, which is discussed in this review.

Indolyl Aryl Sulphones as HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitors: Synthesis, Biological Evaluation and Binding Mode Studies of New Derivatives at Indole-2-carboxamide

New non-nucleoside reverse transcriptase inhibitors (NNRTIs) that are active against the commonly occurring mutations of HIV are urgently needed for the treatment of AIDS. We synthesized new NNRTIs of the indolyl aryl sulphone (IAS) family, which are endowed with high antiviral potency against HIV-1 wt (wild-type), and the Y181C and K103N-Y181C drug resistant mutant strains. Several new compounds were highly active in lymphocytes infected with primary isolates carrying the K103N-V108I-M184V and L100I-V108I mutations. The design of new IASs was based on three-dimensional quantitative structure-activity relationship (3D QSAR) studies and docking simulations. A cross-docking study was also undertaken to gain some insights in to the binding mode of the newly synthesized IASs in the wt and mutated isoforms of reverse transcriptase.

New indolylarylsulfones as highly potent and broad spectrum HIV-1 non-nucleoside reverse transcriptase inhibitors

New indolylarylsulfone HIV-1 NNRTIs were synthesized to evaluate unexplored substitutions of the benzyl/phenylethyl group linked at the indole-2-carboxamide. Against the NL4-3 HIV-1 WT strain, 17 out 20 compounds were superior to NVP and EFV. Several compounds inhibited the K103N HIV-1 mutant strain at nanomolar concentration and were superior to EFV. Some derivatives were superior to EFV against the Y181C and L100I HIV-1 mutant strains. Against the NL4-3 HIV-1 strain, the enantiomers 24 and 25 showed small differences of activity. In contrast, 24 turned out significantly more potent than 25 against the whole panel of mutant HIV-1 strains. The docking studies suggested that the difference in the observed inhibitory activities of 24 and 25 against the K03N mutation could be due to a kinetic rather than affinity differences.

Arylsulfone-based HIV-1 non-nucleoside reverse transcriptase inhibitors

HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) represent one of the most significant classes of drugs for the treatment of AIDS/HIV infection. Over the past two decades several potent arylsulfone-based HIV-1 NNRTIs and related analogs have been developed. This review provides an essential overview of the structure–activity relationships of the arylsulfone-based HIV-1 NNRTIs. Furthermore, structural information useful for the design and development of new sulfur containing NNRTIs with enhanced antiretroviral activity against HIV-1 wild type and clinically relevant drug resistant HIV-1 mutant strains will be discussed.

New nitrogen containing substituents at the indole-2-carboxamide yield high potent and broad spectrum indolylarylsulfone HIV-1 non-nucleoside reverse transcriptase inhibitors

New indolylarylsulfone (IAS) derivatives bearing nitrogen containing substituents at the indole-2-carboxamide inhibited the HIV-1 WT in MT-4 cells at low nanomolar concentrations. In particular, compound 9 was uniformly effective against the mutant Y181C, Y188L, and K103N HIV-1 strains; it was highly active against the multidrug resistant mutant IRLL98 HIV-1 strain bearing the K101Q, Y181C, and G190A mutations conferring resistance to NVP, DLV, and EFV and several HIV-1 clades A in PBMC.

Indolylarylsulfones as HIV-1 non-nucleoside reverse transcriptase inhibitors: new cyclic substituents at indole-2-carboxamide

New indolylarylsulfone derivatives bearing cyclic substituents at indole-2-carboxamide linked through a methylene/ethylene spacer were potent inhibitors of the WT HIV-1 replication in CEM and PBMC cells with inhibitory concentrations in the low nanomolar range. Against the mutant L100I and K103N RT HIV-1 strains in MT-4 cells, compounds 20, 24-26, 36, and 40 showed antiviral potency superior to that of NVP and EFV. Against these mutant strains, derivatives 20, 24-26, and 40 were equipotent to ETV. Molecular docking experiments on this novel series of IAS analogues have also suggested that the H-bond interaction between the nitrogen atom in the carboxamide chain of IAS and Glu138:B is important in the binding of these compounds. These results are in accordance with the experimental data obtained on the WT and on the mutant HIV-1 strains tested.

Looking for an active conformation of the future HIV type-1 non-nucleoside reverse transcriptase inhibitors

HIV type-1 (HIV-1) non-nucleoside reverse transcriptase inhibitors (NNRTIs) are key drugs of highly active antiretroviral therapy (HAART) in the clinical management of AIDS/HIV infection. NNRTI-based HAART regimes effectively suppress viral reproduction, are not cytotoxic and show favourable pharmacokinetic properties. First-generation NNRTIs suffer the rapid selection of viral variants, hampering the binding of inhibitors into the reverse transcriptase (RT) non-nucleoside binding site (NNBS). Efforts to improve these first inhibitors led to the discovery of second-generation NNRTIs that proved to be effective against the drug-resistant mutant HIV-1 strains. The success of such agents launched a new season of NNRTI design and synthesis. This paper reviews the characteristics of second-generation NNRTIs, including etravirine, rilpivirine, RDEA-806, UK-453061, BIRL 355 BS, IDX 899, MK-4965 and HBY 097. In particular, the binding modes of these inhibitors into the NNBS of the HIV-1 RT and the most clinically relevant mutant RTs are analysed and discussed.

Indolylarylsulfones bearing natural and unnatural amino acids. Discovery of potent inhibitors of HIV-1 non-nucleoside wild type and resistant mutant strains reverse transcriptase and coxsackie B4 virus

New potent indolylarylsulfone (IAS) HIV-1 NNRTIs were obtained by coupling natural and unnatural amino acids to the 2-carboxamide and introducing different electron-withdrawing substituents at position 4 and 5 of the indole nucleus. The new IASs inhibited the HIV-1 replication in human T-lymphocyte (CEM) cells at low/subnanomolar concentration and were weakly cytostatic. Against the mutant L100I, K103N, and Y181C RT HIV-1 strains in CEM cells, sulfones 3, 4, 19, 27, and 31 were comparable to EFV. The new IASs were inhibitors to Coxsackie B4 virus at low micromolar (2-9 microM) concentrations. Superimposition of PLANTS docked conformations of IASs 19 and 9 revealed different hydrophobic interactions of the 3,5-dimethylphenyl group, for which a staking interaction with Tyr181 aromatic side chain was observed. The binding mode of 19 was not affected by the L100I mutation and was consistent with the interactions reported for the WT strain.

6-[1-(4-Fluorophenyl)methyl-1H-pyrrol-2-yl)]-2,4-dioxo-5-hexenoic acid ethyl ester a novel diketo acid derivative which selectively inhibits the HIV-1 viral replication in cell culture and the ribonuclease H activity in vitro

The human immunodeficiency virus-type 1 (HIV-1) reverse transcriptase (RT) is a multifunctional enzyme which displays DNA polymerase activity, which recognizes RNA and DNA templates, and a degradative ribonuclease H (RNase H) activity. While both RT functions are required for retroviral replication, until now only the polymerase function has been widely explored as drug target. We have identified a novel diketo acid derivative, 6-[1-(4-fluorophenyl)methyl-1H-pyrrol-2-yl)]-2,4-dioxo-5-hexenoic acid ethyl ester (RDS 1643), which inhibits in enzyme assays the HIV-1 RT-associated polymerase-independent RNase H activity but has no effect on the HIV-1 RT-associated RNA-dependent DNA polymerase (RDDP) activity and on the RNase H activities displayed by the Avian Myeloblastosis Virus and E. coli. Time-dependence studies revealed that the compound is active independently on the order of its addition to the reaction mixture, and inhibition kinetics studies demonstrated that RDS 1643 inhibits the RNase H activity noncompetitively, with a K(I) value of 17 microM. When RDS 1643 was combined with non-nucleoside RT inhibitors (NNRTI), such as efavirenz and nevirapine, results indicated that RDS 1643 does not affect the NNRTIs anti-RDDP activity and that, vice versa, the NNRTIs do not alter the RNase H inhibition by RDS 1643. When assayed on the viral replication in cell-based assays, RDS 1643 inhibited the HIV-1(IIIB) strain with an EC(50) of 14 microM. Similar results were obtained against the Y181C and Y181C/K103N HIV-1 NNRTI resistant mutant strains. RDS 1643 may be the first HIV-1 inhibitor selectively targeted to the viral RT-associated RNase-H function.