A platform for designing HIV integrase inhibitors. Part 1: 2-hydroxy-3-heteroaryl acrylic acid derivatives as novel HIV integrase inhibitor and modeling of hydrophilic and hydrophobic pharmacophores

We present a novel series of HIV integrase inhibitors, showing IC₅₀s ranging from 0.01 to over 370 μM in an enzymatic assay. Furthermore, pharmacophore modeling study for the inhibitors was carried out to elucidate the structure–activity relationships. Finally, we found a 3D-pharmacophore model, which is composed of a hydrophilic and a hydrophobic domain, providing valuable information for designing other novel types of integrase inhibitors.     

Determination of an investigational HIV integrase inhibitor in human plasma using high performance liquid chromatography with tandem mass spectrometric detection

An HPLC-MS/MS assay for the determination of an HIV integrase inhibitor, 5-(1,1-dioxido-1,2-thiazinan-2-yl)-N-(4-fluorobenzyl)-8-hydroxy-1,6-naphthyridine-7-carboxamide (I) in human plasma has been developed and validated. Compound I and a stable isotope labeled internal standard (II) were isolated from 0.5 mL plasma samples by solid phase extraction using an Ansys SPEC C-8 96-well plate. Extracts were separated on a Hypersil BDS C-18 HPLC column (3.0 mmx50 mm, 3 microm) with a mobile phase consisting of 25 mM ammonium formate pH 3.0:acetonitrile (60:40) vol%/vol% pumped at 0.5 mL/min. A Sciex API 365 mass spectrometer equipped with an atmospheric pressure chemical ionization source was operated in selected reaction monitoring (SRM) mode with the precursor-to-product ion transitions m/z 431-->109 (I) and m/z 437-->115 (II) used for quantitation. The assay was validated over the concentration range of 10-5000 ng/mL and was found to have acceptable accuracy, precision, linearity, and selectivity. The mean extraction recovery from spiked plasma samples was 69%. The intra-day accuracy of the assay was within 4% of nominal and intra-day precision was better than 4% C.V. Following a 200 mg dose of the compound administered to human subjects, concentrations of I ranged from 21.1 to 1500 ng/mL in plasma samples collected up to 12 h after dosing. Inter-day accuracy and precision results for quality control samples run over a 3-month period alongside clinical samples showed mean accuracies of within 6% of nominal and precision better than 3.5% C.V.     

Synthesis and evaluation of substituted 4-arylimino-3-hydroxybutanoic acids as potential HIV-1 integrase inhibitors

A series of readily accessible 4-arylimino-3-hydroxybutanoic acids have been prepared and evaluated as potential HIV-1 Integrase inhibitors. None of the ligands exhibited significant toxicity against human embryonic kidney (HEK 293) cells, while five of them showed activity against HIV-1 integrase – the most active (6c) with an IC₅₀ value of 3.5?μM. In silico docking studies indicate the capacity of ligand 6c to interact with several amino acid residues and the two Mg²⁺ cations in the HIV-1 integrase receptor cavity.     

Synthesis and biological evaluation of 5-fluoroquinolone-3-carboxylic acids as potential HIV-1 integrase inhibitors

A series of new quinolone-3-carboxylic acids as HIV-1 integrase inhibitors featuring a fluorine atom at C-5 position were synthesized and evaluated for their antiviral activity in C8166 cell culture. These newly synthesized compounds showed anti-HIV activity against wild-type virus with an EC₅₀ value ranging from 29.85 to 0.032 μΜ. The most active compound 4e exhibited activity against wild-type virus and the mutant virus A17 with an EC₅₀ value of 0.032 and 0.082 μΜ, respectively. Preliminary structure–activity relationship of these 5-fluoroquinolone-3-carboxylic acids was also investigated.     

Synthesis of amino acid derived seven-membered lactams by RCM and their evaluation against HIV protease

A versatile synthesis of hydroxylated and epoxy 1-azepin 2-ones substituted at N1, C-3 and C-4 or C-7 has been developed. The sequence involves ring-closing metathesis of an amino acid derived diene amide, followed by either epoxidation or dihydroxylation, of the resulting alkene. Assay of the product epoxides (10, 18, 25) and diols (9a, 17, 24) against HIV protease reveals micromolar inhibition.     

Synthesis and evaluation of 1-phenyl-1H-1,2,3-triazole-4-carboxylic acid derivatives as xanthine oxidase inhibitors

This study mainly focused on the modification of the X² position in febuxostat analogs. A series of 1-phenyl-1H-1,2,3-triazole-4-carboxylic acid derivatives (1a-s) with an N atom occupying the X² position was designed and synthesized. Evaluation of their inhibitory potency in vitro on xanthine oxidase indicated that these compounds exhibited micromolar level potencies, with IC₅₀ values ranging from 0.21 µM to 26.13 μM. Among them, compound 1s (IC₅₀ = 0.21 μM) showed the most promising inhibitory effects and was 36-fold more potent than allopurinol, but was still 13-fold less potent than the lead compound Y-700, which meant that a polar atom fused at the X² position could be unfavorable for potency. The Lineweaver-Burk plot revealed that compound 1s acted as a mixed-type xanthine oxidase inhibitor. Analysis of the structure-activity relationships demonstrated that a more lipophilic ether tail (e.g., meta-methoxybenzoxy) at the 4′-position could benefit the inhibitory potency. Molecular modeling provided a reasonable explanation for the structure–activity relationships observed in this study.     

Synthesis and biological evaluation of 4-fluoroproline and 4-fluoropyrrolidine-2-acetic acid derivatives as new GABA uptake inhibitors

Preparation for the N-alkylated derivatives of enantiomerically pure (2S)-4-fluoroproline and (2S)-4-fluoropyrrolidine-2-acetic acid is described. The final compounds were evaluated as potential GAT-1 uptake inhibitors via cultured cell lines expressing mouse GAT-1. Compared with their corresponding 4-hydroxy compounds, these derivatives exhibited slight improvement on their inhibitory potency, but still much weaker than their corresponding compounds with no substituents at the C-4 of the pyrrolidine moiety, with the most potent affinity being about 1/15 fold as that of Tiagabine. The drastic decrease of their affinity may arise from sharp reduction of their basicity due to strong inductive effect of the 4-fluorine. However the configuration of the C-4 linking fluorine did not have much influence on their affinity for GAT-1.     

Synthesis and biological evaluation of novel N-substituted nipecotic acid derivatives with an alkyne spacer as GABA uptake inhibitors

In this study, we present the synthesis and structure–activity relationships (SAR) of novel N-substituted nipecotic acid derivatives closely related to (S)-SNAP-5114 (2) in the pursuit of finding new and potent mGAT4 selective inhibitors. By the use of iminium ion chemistry, a series of new N-substituted nipecotic acid derivatives containing a variety of heterocycles, and an alkyne spacer were synthesized. Biological evaluation of the prepared compounds showed, how the inhibitory potency and subtype selectivity for the murine GABA transporters (mGATs) were influenced by the performed modifications.     

Synthesis and evaluation of N-substituted nipecotic acid derivatives with an unsymmetrical bis-aromatic residue attached to a vinyl ether spacer as potential GABA uptake inhibitors

γ-Amino butyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian central nervous system (CNS). A malfunction of the GABAergic neurotransmission is connected to several neuronal disorders like epilepsy, Alzheimer’s disease, neuropathic pain, and depression. One possibility to enhance GABA levels in the synaptic cleft is to inhibit mGAT1, one of the four known plasma membrane bound GABA transporters, which is considered the most important GABA transporter subtype, being in charge of the removal of GABA from the synaptic cleft after a neuronal impulse. Lipophilic derivatives of nipecotic acid like Tiagabine (Gabitril®), an approved drug used in add-on therapy of epilepsy, are known to inhibit uptake of mGAT1 with high subtype selectivity and affinity. We synthesized new N-substituted nipecotic acid derivatives with a vinyl ether spacer and an unsymmetrical bis-aromatic residue, which carries fluorine substituents at various positions of the aromatic ring-system. The new compounds were characterized with respect to their potency and subtype selectivity as mGAT1 inhibitors.     

Non-nucleoside HIV-1 reverse-transcriptase inhibitors. Part 10. Synthesis and anti-HIV activity of 5-alkyl-6-(1-naphthylmethyl)pyrimidin-4(3H)-ones with a mono- or disubstituted 2-amino function as novel 'dihydro-alkoxy-benzyl-oxopyrimidine' (DABO) analogues

A series of structurally related 2,5-disubstituted 6-(1-naphthylmethyl)-pyrimidin-4(3H)-ones, compounds 6a-6r, were synthesized and evaluated for their in vitro anti-HIV activities in MT-4 cells. Most of the new compounds investigated showed moderate-to-good activities against wild-type HIV-1, with IC(50) values in the range 5.64-0.21 microM. Compound 6d was the most potent congener (IC(50)=0.21 microM, SI=724) in inhibiting HIV-1 replication, which is ca. 25 times more effective than the reference compound 2',3'-dideoxyinosine (DDI). Preliminary structure-activity relationship (SAR) studies revealed that both modulation of the amino function at C(2) and of the alkyl group at C(5) of the pyrimidine ring are crucial for high anti-HIV-1 activity.     

Synthesis and biological evaluation of novel N-substituted nipecotic acid derivatives with a trans-alkene spacer as potent GABA uptake inhibitors

Our study presents the synthesis and structure-activity relationship (SAR) of novel N-substituted nipecotic acid derivatives closely related to DDPM-1457 [(S)-2a], a chemically stable analog of (S)-SNAP-5114 (1), in the pursuit of finding new and potent mGAT4 selective inhibitors. Iminium ion chemistry served as key step for the preparation of the desired, new N-substituted nipecotic acid derivatives containing a variety of different heterocycles attached to the nipecotic acid moiety via a trans-alkene spacer. The target compounds were characterized with regard to their potency at and subtype selectivity for the GABA transporters mGAT1-mGAT4.