A historical sketch of the discovery and development of HIV-1 integrase inhibitors

Liquid-assisted mechanochemical synthesis, crystallographic, theoretical and molecular docking study on HIV instasome of novel copper complexes: (µ-acetato)-bis(2,2'-bipyridine)-copper and bromidotetrakis(2-methyl-1H-imidazole)-copper bromide

In the present work the two new Cu(II) complexes, (µ-acetato)-bis(2,2'-bipyridine)-copper [Cu(bpy)2(CH3CO2)] and bromidotetrakis(2-methyl-1H-imidazole)-copper bromide [Cu(2-methylimid)4Br]Br have been synthesized by liquid assisted mechanochemical method. The [Cu(bpy)2(CH3CO2)] complex (1) and [Cu(2-methylimid)4Br]Br complex (2) characterised by IR and UV-visible spectroscopy and the structure are confirmed by XRD diffraction studies. Complex (1) crystallized in the Monoclinic with the space group of C2/c where a = 24.312(5) Å, b = 8.5892(18) Å, c = 14.559(3) Å, α = 90°, β = 106.177(7)° and γ = 90° and Complex (2) crystallized in the Tetragonal with the space group of P4nc, a = 9.9259(2) Å, b = 9.9259(2) Å, c = 10.9357(2) Å, α = 90°, β = 90° and γ = 90°. The complex (1) has distorted octahedral geometry where the acetate ligand showed bidentate bridging with the central metal ion and complex (2) has slightly deformed square pyramidal geometry. The HOMO-LUMO energy gap value and the low chemical potential showed that the complex (2) is stable and difficult to polarize compare to complex (1). The molecular docking study of complexes with the HIV instasome nucleoprotein showed the binding energy values - 7.1 and - 5.3 kcal/mol for complex (1) and complex (2) respectively. The negative binding energy values showed the complexes have affinity to bind with HIV instasome nucleoproteins. The in-silico pharmacokinetic study of the complex (1) and complex (2) showed non AMES toxicity, non-carcinogens and low honey Bee toxicity but weakly inhibit Human Ether-a-go-go-related gene.

Cytotoxic effect, enzyme inhibition, and in silico studies of some novel N-substituted sulfonyl amides incorporating 1,3,4-oxadiazol structural motif

Abstract

The acetylcholinesterase and carbonic anhydrase inhibitors (AChEIs and hCAIs) remain key therapeutic agents for many bioactivities such as anti-Alzheimer and antiobesity antiepileptic, anticancer, antiinfective, antiglaucoma, and diuretic effects. Here, it has been attempted to discover novel multi-target AChEIs and hCAIs that are highly potent, orally bioavailable, may be brain penetrant, and have higher effectiveness at lower doses than tacrine and acetazolamide. After detailed investigations both in vitro and in silico, novel N-substituted sulfonyl amide derivatives (6a–j) were determined to be highly potent inhibitors for AChE and hCAs (K_Is are in the range of 23.11–52.49 nM, 18.66–59.62 nM, and 9.33–120.80 nM for AChE, hCA I, and hCA II, respectively). Moreover, according to the cytotoxic effect studies, such as the ADME-Tox, cortex neuron cells, and neuroblastoma SH-SY5Y cell line, compounds 6a, 6d, and 6h, which are the most potent representative versus the target enzymes, were identified as orally bioavailable, highly selective, and brain preferentially distributed AChEIs and hCAIs. The docking studies revealed precise binding modes between 6a, 6d, and 6h and hCA II, hCA I, and AChE, respectively. The results presented here might provide a solid basis for further investigation into more potent AChEIs and hCAIs.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11030-022-10422-8.

Recent updates on Synthetic Strategies and Biological Potential of 1,3,4-oxadiazole: Review

Abstract:

Among the large variety of nitrogen and oxygen-containing heterocycles, 1,3,4-oxadiazole, the scaffold, has attracted considerable attention owing to its ability to show an extensive range of pharmacological actions. According to literature investigations, prepared 1,3,4-oxadiazole and its derivative are pharmacologically significant and consist of a variety of activities, such as anticonvulsant, anticancer, antioxidant, anti-inflammatory, antibacterial, antidiabetic, etc. These heterocyclics are formed mainly by the cyclization reactions of various reactants under diverse reaction circumstances. Therefore, significant efforts of organic chemists have been directed towards the synthesis of new drug candidates containing 1,3,4-oxadiazole subunits connected to an established potential pharmacophore to improve the efficacy and potency. This article aims to highlight recent publications on the various synthesis techniques of 1,3,4-oxadiazole and related compounds over the previous ten years (2011–2021). The purpose of this review is to help researchers by summarizing several synthetic strategies for synthesizing oxadiazole.

Method development and validation for Cabotegravir and Rilpivirine by using HPLC and its degradants are characterized by LCMS and FTIR

Background

Using a Symmetry C18 (4.6 × 150 mm, 3.5) column, a high-performance liquid chromatographic method for quantification of Rilpivirine and Cabotegravir in active pharmaceutical ingredients was developed and validated. The mobile phase is made up of buffer, acetonitrile, and 0.1 percent formic acid in a 20:80v/v ratio. The flow rate was kept constant at 1.0 ml/min, and detection was accomplished through absorption at 231 nm with a photodiode array detector.

Results

The calibration curve was linear, with a regression coefficient (R2) value of 0.999 and concentrations ranging from 30 to 450 g/ml of Rilpivirine and 20–300 g/ml of Cabotegravir. The method's LOD and LOQ were 0.375 g/ml, 1.238 g/ml, and 0.25 g/ml, 0.825 g/ml for Rilpivirine and Cabotegravir, respectively.

Conclusions

In the forced degradation studies, the degradants were characterized by using LCMS and FTIR. The current application was found to be simple, economical, and suitable, and validated according to ICH guidelines.

Synthetic approaches to unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles and their MAO-B inhibitory activity. A review

Selective monoamine oxidase type B (MAO-B) inhibitors are currently used as coadjuvants for treating early motor symptoms of Parkinson's disease. Aiming at the elucidation of MAO-B inhibitors with 1,3,4-oxadiazole scaffolds, we make a comprehensive update on the new and old chemical methods employed for the synthesis of the unsymmetrical oxadiazole derivatives that lead to high yield compounds. We summarize a state of the selective MAO-B inhibitors with oxadiazole scaffold, describing the results, structures, structure-activity relationships (SARs) and medicinal chemistry strategies over the years. The analysis of the recent papers would facilitate tracking the increasing number of oxadiazole derivatives as new chemical spaces with MAO-B inhibitory potential designed to ensure the safe use of the compounds and elimination of the unwanted drug-drug interactions.

Selenylated-oxadiazoles as promising DNA intercalators: Synthesis, electronic structure, DNA interaction and cleavage

A series of selenylated-oxadiazoles were prepared and their interaction with DNA was investigated. The photophysical studies showed that all the selenylated compounds presented absorption between 270 and 329 nm, assigned to combined n→π* and π→π* transitions, and an intense blue emission (325-380 nm) with quantum yield in the range of Φ _F = 0.1-0.4. DFT and TD-DFT calculations were also performed to study the likely geometry and the excited state of these compounds. Electrochemical studies revealed the ionization potential energies (-5.13 to -6.01 eV) and electron affinity energies (-2.25 to -2.83 eV), depending directly on the electronic effect (electron-donating or electron-withdrawing) of the substituent attached to the product. Finally, the UV-Vis DNA interaction experiments indicated that the compounds can interact with the DNA molecule due to intercalation, except for 3g (which interacted via electrostatic interaction). Plasmid cleavage assay presented positive results only for 3f that presented the strongest interaction results. These results made the tested selenylated-oxadiazoles as suitable structures for the development of drugs and the design of structurally-related therapeutics.

De novo design based identification of potential HIV-1 integrase inhibitors: A pharmacoinformatics study

In the present study, pharmacoinformatics paradigms include receptor-based de novo design, virtual screening through molecular docking and molecular dynamics (MD) simulation are implemented to identify novel and promising HIV-1 integrase inhibitors. The de novodrug/ligand/molecule design is a powerful and effective approach to design a large number of novel and structurally diverse compounds with the required pharmacological profiles. A crystal structure of HIV-1 integrase bound with standard inhibitor BI-224436 is used and a set of 80,000 compounds through the de novo approach in LigBuilder is designed. Initially, a number of criteria including molecular docking, in-silico toxicity and pharmacokinetics profile assessments are implied to reduce the chemical space. Finally, four de novo designed molecules are proposed as potential HIV-1 integrase inhibitors based on comparative analyses. Notably, strong binding interactions have been identified between a few newly identified catalytic amino acid residues and proposed HIV-1 integrase inhibitors. For evaluation of the dynamic stability of the protein-ligand complexes, a number of parameters are explored from the 100 ns MD simulation study. The MD simulation study suggested that proposed molecules efficiently retained their molecular interaction and structural integrity inside the HIV-1 integrase. The binding free energy is calculated through the Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) approach for all complexes and it also explains their thermodynamic stability. Hence, proposed molecules through de novo design might be critical to inhibiting the HIV-1 integrase.

Design, synthesis, chemical characterization, biological evaluation, and docking study of new 1,3,4-oxadiazole homonucleoside analogs

Herein, we report the synthetic strategies and characterization of some novel 1,3,4-oxadiazole homonucleoside analogs that are relevant to potential antitumor and cytotoxic activities. The structure of all compounds is confirmed using various spectroscopic methods such as ¹H-NMR, ¹³C-NMR, HRMS, and FTIR. These compounds were evaluated against three human cancer cell lines (MCF-7, SKBR3, and HL60 Cell Line). Preliminary investigations showed that the cytotoxic activity was markedly dependent on the nucleobase. Introduction of 5-Iodouracil 4g and theobromine 6b proved to be extremely beneficial even they were more potent than the reference drug (DOX). Also, the synthesized compounds were tested for their antiviral activities against the human varicella-zoster virus (VZV). The product 4h was (6-azauracil derivative) more potent to the reference (acyclovir) against the deficient TK - VZV strain by about 2-fold. Finally, molecular docking suggested that the anticancer activities of compounds 6b and 4g mediated by inhibiting dual proteins EGFR/HER2 with low micromolar inhibition constant Ki range. The 1,3,4-oxadiazole homonucleosides showed a strong affinity to binding sites of target proteins by forming H-bond, carbon-hydrogen bond, Pi-anion, Pi-sulfur, Pi-sigma, alkyl, and Pi-alkyl interactions.

Metabolic, mitochondrial, renal and hepatic safety of enfuvirtide and raltegravir antiretroviral administration: Randomized crossover clinical trial in healthy volunteers

Context

Classical antiretroviral agents may acutely impact on metabolic, mitochondrial, renal and hepatic function in HIV-infected and uninfected persons. Fusion and integrase inhibitors are supposed to be safer, but have been scarcely investigated. To avoid any interference with HIV or other antiretrovirals, we assessed markers of these toxicities in healthy adult volunteers treated with Enfuvirtide (T20) or Raltegravir (RAL).

Methods

Twenty-six healthy participants were randomized to T20/90mg vs. placebo (n = 12) or RAL/400mg vs. placebo (n = 14) every 12h in two 7-day periods separated by a 4-week washout period. Major end-points were changes in lipid profile (total cholesterol, high-density-lipoprotein (HDL)-cholesterol, low-density-lipoprotein (LDL)-cholesterol, triglycerides), insulin resistance (glucose) and mitochondrial toxicity (mitochondrial DNA content–mtDNA–in peripheral blood mononuclear cells). Renal and hepatic toxicity (creatinine, alanine transaminase (AST), alanine aminotransferase (ALT), bilirubin and total plasma proteins) and overall safety were also analysed. Effect of period, treatment, and basal measures were evaluated for each end-point.

Results

Neither T20-administration nor RAL-administration yielded to any statistic significant change in the markers of metabolic, mitochondrial, renal or hepatic toxicity assessed. No symptoms indicative of drug toxicity were neither found in any subject.

Conclusions

In absence of HIV infection, or concomitant treatment, short-term exposure to T20 or RAL in healthy adult volunteers did not lead to any indicative changes in toxicity markers thus presuming the safe profile of both drugs.

Oxadiazole-An Important Bioactive Scaffold for Drug Discovery and Development Process Against HIV and Cancer- A Review

Background:

Acquired immunodeficiency syndrome (AIDS) and cancer treatment have been a major task for research scientists and pharmaceutical industry for the last many years. Seeking to the development, many promising chemical entities especially five-membered heterocyclic rings like oxadiazole have revealed good anticancer and anti HIV activities. The current review enlists some recently developed anti-HIV and anti-cancer oxadiazole moieties.

Methods:

on the basis of structural modification for the syntheses of new oxadiazole analogs, the new anti-HIV and anti-cancer agents have been summarized, which can improve treatment of AIDs and cancer.

Results:

The oxadiazole ring is more potent in comparison to some other heterocyclic rings (five and six membered) towards anti-HIV and anti-cancer activities. The important mechanisms involved for anti HIV and anticancer activity are mainly inhibition of enzymes like protease, HIV-integrase, telomerase, histone deacetylase, methionine amino peptidase, thymidylate synthase and focal adhesion kinase and inhibition of some growth factors.

Conclusion:

By reviving the past literature about 50 most potent oxadiazole derivatives, depending upon activity and structural modifications, have been selected as potent anti-HIV, and anti-cancer agents. Thus, oxadiazole seems to be a ‘privileged structure’ for further screening and syntheses of the new drug analogs against life threatening HIV and cancer like diseases.

Non-Cryogenic Structure and Dynamics of HIV-1 Integrase Catalytic Core Domain by X-ray Free-Electron Lasers

HIV-1 integrase (HIV-1 IN) is an enzyme produced by the HIV-1 virus that integrates genetic material of the virus into the DNA of infected human cells. HIV-1 IN acts as a key component of the Retroviral Pre-Integration Complex (PIC). Protein dynamics could play an important role during the catalysis of HIV-1 IN; however, this process has not yet been fully elucidated. X-ray free electron laser (XFEL) together with nuclear magnetic resonance (NMR) could provide information regarding the dynamics during this catalysis reaction. Here, we report the non-cryogenic crystal structure of HIV-1 IN catalytic core domain at 2.5 Å using microcrystals in XFELs. Compared to the cryogenic structure at 2.1 Å using conventional synchrotron crystallography, there was a good agreement between the two structures, except for a catalytic triad formed by Asp64, Asp116, and Glu152 (DDE) and the lens epithelium-derived growth factor binding sites. The helix III region of the 140-153 residues near the active site and the DDE triad show a higher dynamic profile in the non-cryogenic structure, which is comparable to dynamics data obtained from NMR spectroscopy in solution state.

A transition metal-free approach towards synthesis of β-carboline tethered 1,3,4-oxadiazoles via oxidative C–O bond formation

An efficient protocol has been developed for one-pot synthesis of biologically interesting β-carboline substituted 1,3,4-oxadiazoles via an I₂-assisted oxidative C–O bond formation strategy.

Reverse-Phase Chromatographic Determination and Intrinsic Stability Behavior of 5-[(4-Chlorophenoxy)Methyl]-1,3,4-Oxadiazole-2-Thiol

The study describes the development and preliminary validation of a simple reverse-phase chromatographic method for determination of a novel drug candidate, 5-[(4-chlorophenoxy) methyl]-1,3,4-oxadiazole-2-thiol (OXCPM), in bulk and stressed solution, in order to find out the intrinsic stability behavior of the compound. Isocratic elution was carried out at a flow rate of 1.0 mL min-1 through a Promosil C18 column maintained at 25 °C, using the mobile phase comprising acetonitrile and aqueous o-H3PO4 (pH 2.67) (1:1, V/V). Detection was performed at 258 nm. The response of the detector was linear in a concentration range of 1.25-50.00 μg mL-1 with the correlation coefficient of 0.9996 ± 0.0001. Cumulative intra-day, inter-day and inter-instrument accuracy (99.5 ± 1.0, 100.2 ± 1.0 and 100.3 ± 0.4 %, resp.) with RSD less than 5 % indicated that the method was accurate and precise. The resolution and selectivity factor (>2 and >1, resp.), particularly in copper metal- and dry-heat-stress solutions, depicted the selectivity of the method. OXCPM remained stable under hydrolytic (acidic and neutral pH, ≤ 37 °C), photolytic and moist heat stress conditions. Under alkaline conditions (hydrolytic and photolytic), polar products were formed that eluted very fast through the column (tR < 3.75 min). At room temperature, the compound was susceptible to oxidation by hydrogen peroxide and transition metals. The ionogram of most of the stress solutions indicated the presence of a product having m/z 256, which might be a result of N- or Smethylation or -SH oxidation. The results of the study indicate that the method is selective, sensitive and suitable to be used for determination of OXCPM in bulk and under stress conditions.

Synthesis and antimicrobial evaluation of isoxazole-substituted 1,3,4-oxadiazoles

Synthesis of N-(5-methylisoxazol-3-yl)-2-(5-aryl-1,3,4-oxadiazol-2-yl)acetamides 5a–k was achieved from readily available materials. The compounds were screened for their in vitro antimicrobial activity against representative bacterial and fungal strains. Compounds 5b, 5d and 5f exhibit good activity.

Current Parallel Solid-Phase Synthesis of Drug-like Oxadiazole and Thiadiazole Derivatives for Combinatorial Chemistry

Solid-phase organic synthesis is a powerful tool in the synthesis of small organic molecules and building of libraries of compounds for drug discovery. Heterocyclic compounds are important components of the drug discovery field as well and serve as a core for hundreds of marketed drugs. In particular, oxadiazole and thiadiazole cores are compounds of great interest due to their comprehensive biological activities and structural features. Therefore, a plethora of oxadiazole and thiadiazole synthesis methodologies have been reported to date, including solution and solid-phase synthesis methodologies. In this review, we concentrate on and summarize solid-phase synthetic approaches of the oxadiazole and thiadiazole derivatives.

A safety evaluation of raltegravir for the treatment of HIV

INTRODUCTION

Raltegravir (RAL) was the first commercialized agent from a new drug class with an innovative target, the integrase. Since its introduction in clinical practice RAL has become widely used for the treatment of HIV-1 infected patients. A decade after its approval, this article reviews key evidence from RAL with a special interest on safety outcomes. Areas covered: Pharmacologic, safety and efficacy data of RAL from clinical trials and post-commercialization published reports are hereby summarized after a literature review including PubMed search, relating proceedings and abstracts from relevant international HIV conferences, assessment reports from European and United States regulatory agencies and treatment guidelines (World Health Organization, United States Department of Health and Human Services and European AIDS Clinical Society), up to October 2017. Most frequent search terms were 'raltegravir', 'safety', 'adverse events', 'efficacy' and 'integrase-inhibitors'. Expert opinion: Despite the arrival of new integrase strand transfer inhibitors (INSTIs) with advantages in terms of dosing convenience (elvitegravir, ELV) and higher genetic barrier (dolutegravir, DTG), RAL has stood the test of time and its overall favourable safety profile, without significant appearance of unexpected adverse events, vouch for its relevance in the antiretroviral armamentarium.

Emerging Approaches to Tuberculosis Drug Development: At Home in the Metabolome

Once considered a crowning achievement of modern drug development, tuberculosis (TB) chemotherapy has proven increasingly unable to keep pace with the spread of the pandemic and rise of drug resistance. Efforts to revive the TB drug development pipeline have, in the meantime, faltered. Closer analysis reveals key experimental deficiencies that have hindered our ability to 'reverse engineer' knowledge of antibiotic mechanisms into rational drug development. Here, we discuss the emerging potential of metabolomics; the systems level study of small molecule metabolites, to help overcome these gaps and serve as a unique biochemical bridge between the phenotypic properties of chemical compounds and biological targets.

Development and Identification of a Novel Anti-HIV-1 Peptide Derived by Modification of the N-Terminal Domain of HIV-1 Integrase

The viral enzyme integrase (IN) is essential for the replication of human immunodeficiency virus type 1 (HIV-1) and represents an important target for the development of new antiretroviral drugs. In this study, we focused on the N-terminal domain (NTD), which is mainly involved into protein oligomerization process, for the development and synthesis of a library of overlapping peptide sequences, with specific length and specific offset covering the entire native protein sequence NTD IN 1–50. The most potent fragment, VVAKEIVAH (peptide 18), which includes a His residue instead of the natural Ser at position 39, inhibits the HIV-1 IN activity with an IC₅₀ value of 4.5 μM. Amino acid substitution analysis on this peptide revealed essential residues for activity and allowed us to identify two nonapeptides (peptides 24 and 25), that show a potency of inhibition similar to the one of peptide 18. Interestingly, peptide 18 does not interfere with the dynamic interplay between IN subunits, while peptides 24 and 25 modulated these interactions in different manners. In fact, peptide 24 inhibited the IN-IN dimerization, while peptide 25 promoted IN multimerization, with IC₅₀ values of 32 and 4.8 μM, respectively. In addition, peptide 25 has shown to have selective anti-infective cell activity for HIV-1. These results confirmed peptide 25 as a hit for further development of new chemotherapeutic agents against HIV-1.

2,5-Diaryloxadiazoles and their precursors as novel inhibitors of cathepsins B, H and L

High levels of cathepsins indicated in various pathological conditions like arthritis, cancer progressions, and atherosclerosis explains the need to explore potential inhibitors of these proteases which can be of great therapeutic significance. We, in the present work, report the synthesis of some 2,5-diaryloxadiazoles from N-subsitutedbenzylidenebenzohydrazides. The synthesized compounds were screened for their inhibitory potential on cathepsins B, H and L. Structure Activity Relationship studies show that 2,5-diaryloxadiazoles were less inhibitory than their precursors. 1i and 2k have been found to be most inhibitory to cathepsins B and L. Their Ki values have been calculated as 11.38×10(-8)M and 66.4×10(-8)M for cathepsin B and 4.2×10(-9)M and 47.31×10(-9)M for cathepsin L, respectively. However, cathepsin H activity was maximally inhibited by compounds, 1e and 2c with Ki values of 4.4×10(-7)M and 5.6×10(-7)M, respectively. Enzyme kinetic studies suggest that these compounds are competitive inhibitors to the enzymes. The results have been compared with docking results obtained using iGemDock.

Identification of a dibenzocyclooctadiene lignan as a HIV-1 non-nucleoside reverse transcriptase inhibitor

BACKGROUND

Due to resistance to all classes of anti-HIV drugs and drug toxicity, there is a need for the discovery and development of new anti-HIV drugs.

METHODS

HIV-1 inhibitors were identified and biologically characterized for mechanism of action.

RESULTS

We identified a dibenzocyclooctadiene lignan, termed HDS2 that possessed anti-HIV activity against a wide variety of viral strains with EC50 values in the 1-3 µM range. HDS2 was shown to act as an NNRTI by qPCR and in vitro enzyme assays.

CONCLUSIONS

This compound provides a new scaffold for further optimization of activity through structure-guided design.

Exploring the role of the α-carboxyphosphonate moiety in the HIV-RT activity of α-carboxy nucleoside phosphonates

As α-carboxy nucleoside phosphonates (α-CNPs) have demonstrated a novel mode of action of HIV-1 reverse transcriptase inhibition, structurally related derivatives were synthesized, namely the malonate 2, the unsaturated and saturated bisphosphonates 3 and 4, respectively and the amide 5. These compounds were evaluated for inhibition of HIV-1 reverse transcriptase in cell-free assays. The importance of the α-carboxy phosphonoacetic acid moiety for achieving reverse transcriptase inhibition, without the need for prior phosphorylation, was confirmed. The malonate derivative 2 was less active by two orders of magnitude than the original α-CNPs, while displaying the same pattern of kinetic behavior; interestingly the activity resides in the “L”-enantiomer of 2, as seen with the earlier series of α-CNPs. A crystal structure with an RT/DNA complex at 2.95 Å resolution revealed the binding of the “L”-enantiomer of 2, at the polymerase active site with a weaker metal ion chelation environment compared to 1a (T-α-CNP) which may explain the lower inhibitory activity of 2.

Comparison of Newly Assembled Full Length HIV-1 Integrase With Prototype Foamy Virus Integrase: Structure-Function Prospective

Background

Drug design against human immunodeficiency virus type 1 (HIV-1) integrase through its mechanistic study is of great interest in the area in biological research. The main obstacle in this area is the absence of the full-length crystal structure for HIV-1 integrase to be used as a model. A complete structure, similar to HIV-1 of a prototype foamy virus integrase in complex with DNA, including all conservative residues, is available and has been extensively used in recent investigations.

Objectives

The aim of this study was to determine whether the above model is precisely representative of HIV-1 integrase. This would critically determine the success of any designed drug using the model in deactivation of integrase and AIDS treatment.

Materials and Methods

Primarily, a new structure for HIV-1 was constructed, using a crystal structure of prototype foamy virus as the starting structure. The constructed structure of HIV-1 integrase was simultaneously simulated with a prototype foamy virus integrase on a separate occasion.

Results

Our results indicate that the HIV-1 system behaves differently from the prototype foamy virus in terms of folding, hydration, hydrophobicity of binding site and stability.

Conclusions

Based on our findings, we can conclude that HIV-1 integrase is vastly different from the prototype foamy virus integrase and does not resemble it, and the modeling output of the prototype foamy virus simulations could not be simply generalized to HIV-1 integrase. Therefore, our HIV-1 model seems to be more representative and more useful for future research.

Utilization of Cyanoacetohydrazide and Oxadiazolyl Acetonitrile in the Synthesis of Some New Cytotoxic Heterocyclic Compounds

A (pyridazinyl)acetate derivative was reacted with thiosemicarbazide and hydrazine hydrate to yield spiropyridazinone and acetohydrazide derivatives, respectively. The acetohydrazide derivative was used as a starting material for synthesizing some new heterocyclic compounds such as oxoindolinylidene, dimethylpyrazolyl, methylpyrazolyl, oxopyrazolyl, cyanoacetylacetohydrazide and oxadiazolylacetonitrile derivatives. The behavior of the cyanoacetylacetohydrazide and oxadiazolylacetonitrile derivatives towards nitrogen and carbon nucleophiles was investigated. The assigned structures of the prepared compounds were elucidated by spectral methods (IR, ¹H-NMR (13)C-NMR and mass spectroscopy). Some of the newly prepared compounds were tested in vitro against a panel of four human tumor cell lines, namely hepatocellular carcinoma (liver) HePG-2, colon cancer HCT-116, human prostate cancer PC3, and mammary gland breast MCF-7. Also they were tested as antioxidants. Almost all of the tested compounds showed satisfactory activity.

Ring transformation and antimicrobial activity of indolyl-substituted 2(3H)-furanones

A variety of heterocycles of synthetic and biological importance were prepared from 3-(indol-3-yl-methylene)-5-phenyl-2(3H)-furanone (1) and its hydrazide 2. Compounds 1 and 2 were used for the construction of pyridazin-3(4H)-ones 4 and 6; 1,3,4-oxadiazoles 7, 8, and 10; and 1,2,4-triazoles 12, 14, and 15, all bearing a 3-indolyl moiety. The antimicrobial activities of the synthesized compounds were examined against six types of bacteria and two types of fungi.

An efficient and highly diastereoselective synthesis of GSK1265744, a potent HIV integrase inhibitor

A novel synthesis of GSK1265744, a potent HIV integrase inhibitor, is described. The synthesis is highlighted by an efficient construction of the densely functionalized pyridinone core as well as a highly diastereoselective formation of the acyl oxazolidine moiety. The latter exploits the target molecule's ability to chelate to Mg(2+), a key feature in the integrase inhibitor's mechanism of action.

Novel bio-friendly and non-toxic thiocarbohydrate stabilizers of gold nanoparticles

A new class of stabilizers for gold nanoparticles has been develop with non-toxic thiocarbohydrates that were prepared from d-(+)-gluconic acid δ-lactone and aminoalkylthiols.

Design of novel leads: ligand based computational modeling studies on non-nucleoside reverse transcriptase inhibitors (NNRTIs) of HIV-1

Researchers are on the constant lookout for new antiviral agents for the treatment of AIDS. In the present work, ligand based modeling studies are performed on analogues of substituted phenyl-thio-thymines, which act as non-nucleoside reverse transcriptase inhibitors (NNRTIs) and novel leads are extracted. Using alignment-dependent descriptors, based on group center overlap (SALL, HDALL, HAALL and RALL), an alignment-independent descriptor (S log P), a topological descriptor (Balaban index (J)) and a 3D descriptor dipole moment (μ) and shape based descriptors (Kappa 2 index ((2)κ)), a correlation is derived with inhibitory activity. Linear and non-linear techniques have been used to achieve the goal. Support Vector Machine (SVM, R = 0.929, R(2) = 0.863) and Back Propagation Neural Network (BPNN, R = 0.928, R(2) = 0.861) methods yielded near similar results and outperformed Multiple Linear Regression (MLR, R = 0.915, R(2) = 0.837). The predictive ability of the models are cross-validated using a test dataset (SVM: R = 0.846, R(2) = 0.716, BPNN: R = 0.841, R(2) = 0.707 and MLR: R = 0.833, R(2) = 0.694). It is concluded that the hydrophobicity (S log P) and the polarity (μ) of a ligand and the presence of hydrogen donor (HDALL) moieties are the deciding factors in improving antiviral activity and pharmaco-therapeutic properties. Based on the above findings, a virtual dataset is created to extract probable leads with reasonable antiviral activity as well as better pharmacophoric properties.

The Influence of Bioisosteres in Drug Design: Tactical Applications to Address Developability Problems

The application of bioisosteres in drug discovery is a well-established design concept that has demonstrated utility as an approach to solving a range of problems that affect candidate optimization, progression, and durability. In this chapter, the application of isosteric substitution is explored in a fashion that focuses on the development of practical solutions to problems that are encountered in typical optimization campaigns. The role of bioisosteres to affect intrinsic potency and selectivity, influence conformation, solve problems associated with drug developability, including P-glycoprotein recognition, modulating basicity, solubility, and lipophilicity, and to address issues associated with metabolism and toxicity is used as the underlying theme to capture a spectrum of creative applications of structural emulation in the design of drug candidates.

K10 montmorillonite clays as environmentally benign catalysts for organic reactions

This perspective summarizes the catalytic activity of K10 montmorillonite as a multifunctional catalyst for organic reactions.

Dendritic cells treated with chloroquine modulate experimental autoimmune encephalomyelitis

Chloroquine (CQ), an antimalarial drug, has been shown to modulate the immune system and reduce the severity of experimental autoimmune encephalomyelitis (EAE). The mechanisms of disease suppression are dependent on regulatory T cell induction, although Tregs-independent mechanisms exist. We aimed to evaluate whether CQ is capable to modulate bone marrow-derived dendritic cells (DCs) both phenotypically and functionally as well as whether transfer of CQ-modulated DCs reduces EAE course. Our results show that CQ-treated DCs presented altered ultrastructure morphology and lower expression of molecules involved in antigen presentation. Consequently, T cell proliferation was diminished in coculture experiments. When transferred into EAE mice, DC-CQ was able to reduce the clinical manifestation of the disease through the modulation of the immune response against neuroantigens. The data presented herein indicate that chloroquine-mediated modulation of the immune system is achieved by a direct effect on DCs and that DC-CQ adoptive transfer may be a promising approach for avoiding drug toxicity.

Raltegravir monohydrate

THE HYDRATED TITLE COMPOUND [SYSTEMATIC NAME: N-(4-fluoro-benz-yl)-5-hy-droxy-1-methyl-2-{1-methyl-1-[(5-methyl-1,3,4-oxa-diazol-2-ylcarbon-yl)amino]-eth-yl}-6-oxo-1,6-di-hydro-pyrimidine-4-carb-oxamide monohydrate], C20H21FN6O5·H2O, is recognised as the first HIV integrase inhibitor. In the mol-ecule, the dihedral angles between the mean planes of the pyrimidine ring and the phenyl and oxa-diazole rings are 72.0 (1) and 61.8 (3)°, respectively. The mean plane of the oxa-diazole ring is twisted by 15.6 (3)° from that of the benzene ring, while the mean plane of amide group bound to the oxadiaole ring is twisted by 18.8 (3)° from its mean plane. Intra-molecular O-H⋯O and C-H⋯N hydrogen bonds are observed in the mol-ecule. The crystal packing features O-H⋯O hydrogen bonds, which include bifurcated O-H⋯(O,O) hydrogen bonds from one H atom of the water mol-ecule. In addition, N-H⋯O hydrogen bonds are observed involving the two amide groups. These inter-actions link the mol-ecules into chains along [010].

Chloroquine: modes of action of an undervalued drug

For more than two decades, chloroquine (CQ) was largely and deliberately used as first choice drug for malaria treatment. However, worldwide increasing cases of resistant strains of Plasmodium have hampered its use. Nevertheless, CQ has recently been tested as adjunct therapy in several inflammatory situations, such as rheumatoid arthritis and transplantation procedures, presenting intriguing and promising results. In this review, we discuss recent findings and CQ mechanisms of action vis-à-vis its use as a broad adjunct therapy.