Development of Triazoles and Triazolium Salts Based on AZT and Their Anti-Viral Activity against HIV-1.

We report herein a set of 3'-azido-3'-deoxythymidine (AZT) derivatives based on triazoles and triazolium salts for HIV-1 infection. The compounds were synthesized via click chemistry with Cu(I) and Ru(II) catalysts. Triazolium salts were synthesized by reaction with methyl iodide or methyl triflate in good yields. The antiviral activity of the compounds was tested using two methodologies: In method one the activity was measured on infected cells; in method two a pre-exposure prophylaxis experimental model was employed. For method one the activity of the compounds was moderate, and in general the triazolium salts showed a decreased activity in relation to their triazole precursors. With method two the antiviral activity was higher. All compounds were able to decrease the infection, with two compounds able to clear almost all the infection, while a lower antiviral activity was noted for the triazolium salts. These results suggest that these drugs could play an important role in the development of pre-exposure prophylaxis therapies.

Evaluation of the effect of synthetic compounds derived from azidothymidine on MDA-MB-231 type breast cancer cells.

The present study aimed to investigate the effect of AZT derivates containing tellurium (Te) on human breast cancer cell lines and the mechanisms underlying cell death. The inhibitory effect of AZT and its derivatives (7m and 7r) was determined by the MTT assay (6.25, 12.5, 25, 50 and 100 µM in 24 and 48 h time points), meanwhile the induction of apoptosis and the cell cycle phases was investigated by flow cytometry. The MTT assay showed that AZT derivatives decreased the rate of cell proliferation at concentrations of 12.5 µM, while commercial AZT showed low antitumor potential. In flow cytometric analysis, we demonstrate that the AZT derivatives do not induce apoptosis at the concentration tested and promote the cell cycle arrest in the S phase. Besides, predicted absorption, distribution, metabolization, excretion and toxicity analysis suggest that the compounds possess a good pharmacokinetic profile and possibly less toxicity when compared to conventional AZT. These compounds containing tellurium in their formulation are potential therapeutic agents for breast cancer.

Antibacterial AZT derivative regulates metastasis of breast cancer cells.

Antimicrobial peptides (AMP) with anticancer activity have drawn remarkable attention in modern treatments. However, long peptide length and protease instability are the most addressing factors, which hampers their further development as therapeutic agents. In view of this, herein, we designed and synthesized a series of AZT-based cationic small molecule incorporating a variety of hydrophobic groups and cationic charges, including amine and guanidine groups to mimic the amphipathic structure of AMPs. These compounds were evaluated for their antibacterial activity against Gram-positive and Gram-negative bacteria. Through an extensive structure activity relationship study (SAR), we identified ADG-2e as the most potent antibacterial agent, which exhibited remarkable potency against drug resistant bacterial strains such as MRSA and MDRPA. Further, ADG-2e was examined for their anti-metastatic ability by investigating the cancer cell migration and invasiveness through scratch wound-healing assay and transwell invasive assay, respectively. In addition, time-lapse cell tracking analysis also performed for analyzing the cell movement pattern. Treatment of ADG-2e against metastatic breast cancer cells (MDA-MB-231) suppressed tumor cell migration by multi-directional lamellipodium formation, indicating their anti-metastatic potential. Thus, our cationic AZT based small molecules may evolve as an appealing class of antibacterial agents with anti-metastasis potential.

New phosphazine and phosphazide derivatives as multifunctional ligands targeting acetylcholinesterase and ß-Amyloid aggregation for treatment of Alzheimer's disease.

Phosphazine and phosphazide derivatives are described herein as a new class of selective and potent acetylcholinesterase (AChE) inhibitors and ß-amyloid aggregation inhibitors. Phosphazines (5-7) were synthesized smoothly via a redox-condensation reaction of 1,2-bis(diphenylphosphino)ethane with different amines derivatives in the presence of dialkyl azodicarboxylate (Staudinger reaction) while phosphazides (8) via electrophilic attack of azido derivatives. Structures of the synthesized compounds were justified on the basis of compatible elementary and spectroscopic analyses. All the compounds were evaluated for their acetylcholinesterase inhibitory activity. The most three potent compounds (5b-c and 8b) showing AChE IC50 values (29.85-34.96 nM) comparable to that of donepezil (34.42 nM) were subjected to further investigation by testing their butyrylcholinesterase, MMP-2 and self-induced Aß aggregation inhibition activity. Especially, the coumarin phosphazide derivative (8b) presented the best AChE inhibition selectivity index (IC50 = 34.96 nM, AChE/BuChE; 3.81) together with good inhibition ability against MMP-2 (IC50 = 441.33 nM) and self-induced Aß1-42 aggregation (IC50 = 337.77 nM). In addition, the inhibition of metal-induced Aß aggregation by 8b was confirmed by thioflavine T fluorescence. The most potent effect of 8b was observed on the Zn2+-induced Aß42 aggregation. Kinetic study of compound 8b suggested it to be a competitive AChE inhibitor. Also, it specifically chelates metal and is predicted to be permeable to BBB. It also possesses low toxicity on SH-SY5Y neuroblastoma cells with a safety index of 15.37. In addition, it was demonstrated that compound 8b can improve the cognitive impairment of scopolamine-induced model in mice with % alternations and transfer latency time comparable to that of donepezil. Also, a docking study was carried out and it was in accordance with the in vitro results. These promising in vitro and in vivo findings highlight compound 8b as a possible drug candidate in searching for new multifunctional AD drugs.

Synthesis and evaluation of the anti-hepatitis B virus activity of 4'-Azido-thymidine analogs and 4'-Azido-2'-deoxy-5-methylcytidine analogs: structural insights for the development of a novel anti-HBV agent.

Hepatitis B virus (HBV) infection is a major worldwide health problem that requires the development of improved antiviral therapies. Here, a series of 4'-Azido-thymidine/4'-Azido-2'-deoxy-5-methylcytidine derivatives (6, 10-15) were synthesized, and their anti-HBV activities evaluated. Compounds 10-15 were synthesized via an SNAr reaction of 18, in which the 4-position of the thymine moiety was activated as the 2,4,6-triisopropylbenzenesulfonate. Compounds 11-15 showed no antiviral activity. However, 4'-Azido thymidine (6) and 4'-Azido-2'-deoxy-5-methylcytidine (10) displayed significant anti-HBV activity (EC50 = 0.63 and 5.99 µM, respectively) with no detectable cytotoxicity against MT-2 cells up to 100 µM.

Self-assemblies of 5'-cholesteryl-ethyl-phosphoryl zidovudine.

Anti-HIV prodrugs are recently focused on due to their ability of self-assembly, macrophage targeting, and enhanced antiviral effects. Here, an amphiphilic prodrug of zidovudine, an anti-HIV nucleoside analogue, 5'-cholesteryl-ethyl-phosphoryl zidovudine (CEPZ) was synthesized. CEPZ showed some unique physicochemical properties. The solubility of CEPZ in the noncompetitive solvents chloroform and tetrahydrofuran (THF) was very high based on the hydrogen bonds between zidovudine groups, though CEPZ was sparing soluble in alcohols and almost insoluble in water. The typical amphiphilic property of CEPZ was demonstrated according to the Langmuir monolayers at the air/water interface. The LogP of CEPZ was high to 13.78, indicating the high hydrophobicity of amphiphilic CEPZ similar to phospholipids. Homogenous and stable self-assemblies were formed with the mean size of 128.7nm and the zeta potential of -35.4mV after injecting the CEPZ-in-THF solution into water. Hydrophobic interaction between the cholesteryl moieties of CEPZ could drive molecular self-assembly and lead to the formation of spherical vesicles. CEPZ self-assemblies showed strong stability even under high temperature and gravity probably due to the high surface charge. CEPZ was very slowly degraded in neutral solutions (e.g., pH 7.4), but fast in acid solutions (e.g., pH 5.0) and some tissue homogenates. CEPZ was quickly eliminated from the circulation and distributed into the mononuclear phagocyte system (MPS) including the liver, spleen and lung after bolus intravenous administration of CEPZ self-assemblies to mice. The MPS targeting effect of CEPZ self-assemblies makes them become a promising self-assembled drug delivery system to eradicate the HIV hidden in the macrophages.

Anti-HIV-1 activity determined by ß-galactosidase activity in the multinuclear activation of an indicator assay is comparable with that by a conventional focus counting method.

BACKGROUND: Direct comparison of enzymatic and original blue cell-counting detections with the multinuclear activation of an indicator (MAGI) cells, so far, remains to be performed in parallel. Although inhibitors for reverse transcription solely inhibit the reverse transcription step, those for HIV-1 entry block syncytium formation of HIV-1-infected MAGI cells in addition to the entry (dual inhibition). It raises a concern that reduction of enzymatic activity is artificially influenced by syncytium-blocking activity of inhibitors for entry. METHODS: The MAGI cells with a syncytium inducible strain, HIV-1IIIB, were used for anti-HIV activity determination both with conventional counting with X-Gal staining and measurement of chlorophenol red ß-d-galactopyranoside conversion with a plate reader. RESULTS: Infectivity of HIV-1 in the MAGI cells was highly correlated with both methods. In microscopic observation, small blue cells with single or a couple of nuclei were dominantly observed in the presence of inhibitors for entry, but not in the presence of those for reverse transcription. Actual anti-HIV-1 activities were comparable or moderately sensitive in the chlorophenol red ß-d-galactopyranoside method. CONCLUSIONS: Antiviral activities of inhibitors for entry obtained from both enzymatic and counting methods appear to be comparable, even in infection of a highly syncytia inducible HIV-1IIIB strain.

New organochalcogen multitarget drug: synthesis and antioxidant and antitumoral activities of chalcogenozidovudine derivatives.

In this article we present the synthesis, characterization, and in vitro biological and biochemical activities of new chalcogenozidovudine derivatives as antioxidant (inhibition of TBARS in brain membranes and thiol peroxidase-like activity) as well as antitumoral agents in bladder carcinoma 5637. A prominent response was obtained for the selected chalcogenonucleosides, showing effective antioxidant and antitumoral activities.

Zidovudine-poly(L-lactic acid) solid dispersions with improved intestinal permeability prepared by supercritical antisolvent process.

A supercritical antisolvent (SAS) process for obtaining zidovudine-poly(L-lactic acid) (PLLA) solid dispersions (SDs) was used to attain a better intestinal permeation of this drug. A 3(2) factorial design was used, having as independent variables the ratio 3'-azido-2'3'-dideoxythymidine (AZT)-PLLA and temperature/pressure conditions, as dependent variables the process yield and particle macroscopic morphology. AZT-PLLA production batches were carried out by the SAS process, and the resulting products evaluated via scanning electron microscope, X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared analyses. From the nine possible combinations of tests performed experimentally, only one combination did not produced a solid. The L3 batch of SD, produced with 1:2 (AZT-PLLA) ratio, resulted in a 91.54% yield, with 40% AZT content. Intestinal permeability studies using the AZT-PLLA from L3 batch led to an AZT permeability of approximately 9.87%, which was higher than that of pure AZT (∼3.84%). AZT remained in crystalline form, whereas PLLA remained in semicrystalline form. AZT release is controlled by a diffusion mechanism. It has been demonstrated that it is possible to use PLLA carrier and SAS process to obtain SD, in a single step.

Synthesis and evaluation of 3-hydroxy-3-phenylpropanoate ester­AZT conjugates as potential dual-action HIV-1 Integrase and Reverse Transcriptase inhibitors.

Novel 3-hydroxy-3-phenylpropanoate ester-azidothymidine (AZT) conjugates have been prepared using Baylis-Hillman methodology, and their potential as dual-action HIV-1 Integrase and Reverse Transcriptase inhibitors has been explored using enzyme inhibition and computer modelling techniques; their activity and HeLa cell toxicity have been compared with those of their cinnamate ester analogues.

Synthesis and cytotoxic evaluation of novel ester-triazole-linked triterpenoid-AZT conjugates.

Betulinic acid and analogous naturally occurring triterpenoid acids were transformed into the corresponding propargyl esters and subsequently deployed as substrates for a click chemistry-mediated coupling with azidothymidine (AZT) en route to novel 1,2,3-triazole-tethered triterpenoid-AZT conjugates. Twelve new hybrids were thus prepared and assessed in terms of their cytotoxic activity, revealing an interesting anticancer activity of five triterpenoid-AZT hybrids on KB and Hep-G2 tumor cell lines.

Toward hyperpolarized molecular imaging of HIV: synthesis and longitudinal relaxation properties of (15) N-Azidothymidine.

Previously unreported (15) N labeled Azidothymidine (AZT) was prepared as an equimolar mixture of two isotopomers: 1-(15) N-AZT and 3-(15) N-AZT. Polarization decay of (15) N NMR signal was studied in high (9.4 T) and low (~50 mT) magnetic fields. (15) N T1 values were 45 ± 5 s (1-(15) N-AZT) and 37 ± 2 s (3-(15) N-AZT) at 9.4 T, and 140 ± 16 s (3-(15) N-AZT) at 50 mT. (15) N-AZT can be potentially (15) N hyperpolarized by several methods. These sufficiently long (15) N-AZT T1 values potentially enable hyperpolarized in vivo imaging of (15) N-AZT, because of the known favorable efficient (i.e., of the time scale shorter than the longest reported here (15) N T1 ) kinetics of uptake of injected AZT. Therefore, 3-(15) N-AZT can be potentially used for HIV molecular imaging using hyperpolarized magnetic resonance imaging.

Efficient syntheses of [¹¹C]zidovudine and its analogs by convenient one-pot palladium(0)-copper(I) co-mediated rapid C-[¹¹C]methylation.

The nucleosides zidovudine (AZT), stavudine (d4T), and telbivudine (LdT) are approved for use in the treatment of human immunodeficiency virus (HIV) and hepatitis B virus (HBV) infections. To promote positron emission tomography (PET) imaging studies on their pharmacokinetics, pharmacodynamics, and applications in cancer diagnosis, a convenient one-pot method for Pd(0)-Cu(I) co-mediated rapid C-C coupling of [(11)C]methyl iodide with stannyl precursor was successfully established and applied to synthesize the PET tracers [(11)C]zidovudine, [(11)C]stavudine, and [(11)C]telbivudine. After HPLC purification and radiopharmaceutical formulation, the desired PET tracers were obtained with high radioactivity (6.4-7.0 GBq) and specific radioactivity (74-147 GBq/µmol) and with high chemical (>99%) and radiochemical (>99.5%) purities. This one-pot Pd(0)-Cu(I) co-mediated rapid C-[(11)C]methylation also worked well for syntheses of [methyl-(11)C]thymidine and [methyl-(11)C]4'-thiothymidine, resulting twice the radioactivity of those prepared by a previous two-pot method. The mechanism of one-pot Pd(0)-Cu(I) co-mediated rapid C-[(11)C]methylation was also discussed.

New dinucleoside phosphonate derivatives as prodrugs of 3'-azido-3'-deoxythymidine and ß-L-2',3'-dideoxy-3'-thiacytidine: synthesis and anti-HIV properties.

[Formula: see text]New phosphonate homodimers of 3'-azido-3'-deoxythymidine (AZT) and a phosphonate heterodimer of ß-L-2',3'-dideoxy-3'-thiacytidine (3TC) and AZT were synthesized. The compounds demonstrated moderate anti-HIV activity. Stability of the compounds in human blood serum was studied. A correlation between anti-HIV activity and stability was defined.

A novel synthesis of antiviral nucleoside phosphoramidate and thiophosphoramidate prodrugs via nucleoside H-phosphonamidates.

A novel and efficient method for the preparation of antiviral nucleoside 5'-H-phosphonamidates has been developed. The oxidization of the H-phosphonamidate intermediates with iodine and sulfur afforded nucleoside 5'-phosphoramidates and 5'-thiophosphoramidates in high yields.

Clicking 3'-azidothymidine into novel potent inhibitors of human immunodeficiency virus.

3'-Azidothymidine (AZT) was the first approved antiviral for the treatment of human immunodeficiency virus (HIV). Reported efforts in clicking the 3'-azido group of AZT have not yielded 1,2,3-triazoles active against HIV or any other viruses. We report herein the first AZT-derived 1,2,3-triazoles with submicromolar potencies against HIV-1. The observed antiviral activities from the cytopathic effect (CPE) based assay were confirmed through a single replication cycle assay. Structure-activity-relationship (SAR) studies revealed two structural features key to antiviral activity: a bulky aromatic ring and the 1,5-substitution pattern on the triazole. Biochemical analysis of the corresponding triphosphates showed lower ATP-mediated nucleotide excision efficiency compared to AZT, which along with molecular modeling suggests a mechanism of preferred translocation of triazoles into the P-site of HIV reverse transcriptase (RT). This mechanism is corroborated with the observed reduction of fold resistance of the triazole analogue to an AZT-resistant HIV variant (9-fold compared to 56-fold with AZT).

[Synthesis, properties and anti-HIV activity of novel lipophilic 3'-azido-3'-deoxythymidine conjugates containing functional phosphoric linkages].

One of the approaches to enhance bioavailability of nucleoside reverse transcriptase HIV inhibitors consists in design of their prodrugs based on 1,3-diacylglycerols, which may simulate nature lipids metabolic pathways promoting the improvement of drug delivery to the target cells. Glycerolipidic AZT conjugates with different functional phosphoric centers were synthesized by H-phosphonate technique in the present work. Study of prepared prodrugs sensibility to the chemical and enzymatic hydrolysis (in buffer solution and under the influence of pancreatic lipase) and also study of their anti-HIV activity on the T-lymphoid human MT-4 cells in regarding to virus HIV-1(899A) strain were carried out.

Synthesis and evaluation of coumarin derivatives as potential dual-action HIV-1 protease and reverse transcriptase inhibitors.

Baylis-Hillman-derived 3-(benzylaminomethyl)coumarins have been treated, sequentially, with chloroacetyl chloride and propargylamine to afford alkynylated coumarins as substrates for Click Chemistry reactions with azidothymidine (AZT) in the presence of a Cu(I) catalyst. The dual-action HIV-1 protease (PR) and reverse transcriptase (RT) inhibition potential of the resulting N-benzylated cycloaddition products, and a series of non-benzylated analogues, has been explored using saturation transfer difference (STD) NMR, computer modelling and enzyme inhibition techniques.

Synthesis and evaluation of a dipeptide-drug conjugate library as substrates for PEPT1.

The oligopeptide transporter PEPT1 is considered as a valuable target for prodrug design, but its 3D structure and substrate specificity of PEPT1 are not fully understood. In this study, we designed a focused dipeptide conjugated azidothymidine (AZT) library and described a convenient and efficient solid phase synthesis scheme based on click chemistry. Over 60 candidate structures containing various dipeptide sequences were obtained with high purity, and screened in a PEPT1 overexpressing cell model for their abilities to compete with the known ligand cephalexin. Some of the compounds selected to have medium or high affinity were tested for their in vivo transport in a single-pass intestinal perfusion experiment. Results showed that the designed library contained some new structure features that have high affinities toward PEPT1 and could be further explored for their application in prodrug design and development.