AZT Derivatives Research Articles

Antiviral Effect of 5'-Arylchalcogeno-3-aminothymidine Derivatives in SARS-CoV-2 Infection.

The understanding that zidovudine (ZDV or azidothymidine, AZT) inhibits the RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 and that chalcogen atoms can increase the bioactivity and reduce the toxicity of AZT has directed our search for the discovery of novel potential anti-coronavirus compounds. Here, the antiviral activity of selenium and tellurium containing AZT derivatives in human type II pneumocytes cell model (Calu-3) and monkey kidney cells (Vero E6) infected with SARS-CoV-2, and their toxic effects on these cells, was evaluated. Cell viability analysis revealed that organoselenium (R3a-R3e) showed lower cytotoxicity than organotellurium (R3f, R3n-R3q), with CC50 ≥ 100 µM. The R3b and R3e were particularly noteworthy for inhibiting viral replication in both cell models and showed better selectivity index. In Vero E6, the EC50 values for R3b and R3e were 2.97 ± 0.62 µM and 1.99 ± 0.42 µM, respectively, while in Calu-3, concentrations of 3.82 ± 1.42 µM and 1.92 ± 0.43 µM (24 h treatment) and 1.33 ± 0.35 µM and 2.31 ± 0.54 µM (48 h) were observed, respectively. The molecular docking calculations were carried out to main protease (Mpro), papain-like protease (PLpro), and RdRp following non-competitive, competitive, and allosteric inhibitory approaches. The in silico results suggested that the organoselenium is a potential non-competitive inhibitor of RdRp, interacting in the allosteric cavity located in the palm region. Overall, the cell-based results indicated that the chalcogen-zidovudine derivatives were more potent than AZT in inhibiting SARS-CoV-2 replication and that the compounds R3b and R3e play an important inhibitory role, expanding the knowledge about the promising therapeutic capacity of organoselenium against COVID-19.

Toxicological evaluation of zidovudine and novel chalcogen derivatives in Drosophila melanogaster.

Zidovudine (AZT) is the most commonly prescribed antiviral drug for the treatment of human immunodeficiency virus (HIV) infection. However, its chronic administration causes toxic side effects limiting its use. This study aimed to evaluate the toxicity of different concentrations of AZT and novel chalcogen derivatives (7A, 7D, 7G, 7K, 7M) on locomotion, mitochondrial dysfunction, acetylcholinesterase (AChE) activity, and production of reactive oxygen species (ROS) in adult Drosophila melanogaster. Our results show that AZT and its derivative 7K at a concentration of 10 μM impaired flies'locomotor behavior. Furthermore, AZT and the derivatives 7K, 7A, and 7M induced mitochondrial dysfunction observed by a decrease in oxygen flux through mitochondrial complexes I and II. Neither of the compounds tested affected AChE activity or ROS production in flies. According to these data, AZT derivatives presented the following decreasing order of toxicity: 7K > AZT > 7G > 7A > 7M > 7D. Based on the chemical structure, it is possible to infer that the presence of the seleno-phenyl group in 7A and 7G increases their toxicity compared to compounds 7D and 7M. In addition, compounds 7G, 7M, and 7K with three carbon atoms as spacer were more toxic than analogs containing one carbon atom (7A and 7D). Finally, the insertion of a p-methoxyl group enhances toxicity (7K). Based on these results, excepting 7K, all other chalcogen derivatives presented lower toxicity than AZT and are potential drug candidates.

Synthesis and anti-inflammatory activity evaluation of novel AZT and adenosine derivatives

A five-step procedure was used to synthesize four novel conjugates of AZT and adenosine with quinazolinone scaffold. In the last step, alkynes-1 of quinazolinone were coupled to adenosine azide and AZT by Click chemistry to yield the designed conjugates. Their structures were characterized by full-length data of spectra including 1H-, 13C-NMR and MS. Screening for their in vitro anti-inflammatory activity was performed using Murine macrophage RAW 264.7 cells. The relationship between structure and biological activity was also discussed.

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.

Safety profile of AZT derivatives: Organoselenium moieties confer different cytotoxic responses in fresh human erythrocytes during in vitro exposures

IntroductionThe incorporation of selenium in the structure of nucleosides is a promising strategy to develop novel therapeutic molecules. ObjectiveTo assess the toxic effects of three AZT derivatives containing organoselenium moieties on human erythrocytes. MethodologyFreshly human erythrocytes were acutely treated with AZT and selenium derivatives SZ1 (chlorophenylseleno), SZ2 (phenylseleno) and SZ3 (methylphenylseleno) at concentrations ranging from 10 to 500 μM. Afterwards, parameters related to membrane damage, redox dyshomeostasis and eryptosis were determined in the cells. ResultsThe effects of AZT and derivatives toward erythrocytes differed considerably. Overall, the SZ3 exhibited similar effect profiles to the prototypal AZT, without causing cytotoxicity. Contrary, the derivative SZ1 induced hemolysis and increased the membrane fragility of cells. Reactive species generation, lipid peroxidation and thiol depletion were also substantially increased in cells after exposure to SZ1. δ-ALA-D and Na+/K+-ATPase activities were inhibited by derivatives SZ1 and SZ2. Additionally, both derivatives caused eryptosis, promoting cell shrinkage and translocation of phosphatidylserine at the membrane surface. The size and granularity of erythrocytes were not modified by any compound. ConclusionThe insertion of either chlorophenylseleno or, in a certain way, phenylseleno moietes in the structure of AZT molecule was harmful to erythrocytes and this effect seems to involve a pro-oxidant activity. This was not true for the derivative encompassing methylphenylseleno portion, making it a promising candidate for pharmacological studies.

New hybrids between triterpenoid acids and nucleoside HIV-RT inhibitors

One-pot synthesis of ester-linked conjugates of betulinic, ursolic or oleanolic acids with anti-HIV drugs AZT, derivatives of AZT and 3TC was performed, the resulting conjugates having shown high anti-HIV activities.

Nucleophile-Catalyzed Additions to Activated Triple Bonds. Protection of Lactams, Imides, and Nucleosides with MocVinyl and Related Groups

Additions of lactams, imides, (S)-4-benzyl-1,3-oxazolidin-2-one, 2-pyridone, pyrimidine-2,4-diones (AZT derivatives), or inosines to the electron-deficient triple bonds of methyl propynoate, tert-butyl propynoate, 3-butyn-2-one, N-propynoylmorpholine, or N-methoxy-N-methylpropynamide in the presence of many potential catalysts were examined. DABCO and, second, DMAP appeared to be the best (highest reaction rates and E/Z ratios), while RuCl3, RuClCp*(PPh3)2, AuCl, AuCl(PPh3), CuI, and Cu2(OTf)2 were incapable of catalyzing such additions. The groups incorporated (for example, the 2-(methoxycarbonyl)ethenyl group that we name MocVinyl) serve as protecting groups for the above-mentioned heterocyclic CONH or CONHCO moieties. Deprotections were accomplished via exchange with good nucleophiles: the 1-dodecanethiolate anion turned out to be the most general and efficient reagent, but in some particular cases other nucleophiles also worked (e.g., MocVinyl-inosines can be cleaved with succinimide anion). Some structural and mechanistic details have been accounted for with the help of DFT and MP2 calculations.

Synthesis and Anti‐HIV Properties of New Carbamate Prodrugs of AZT

A series of new 5'-O-carbamate prodrugs of AZT have been prepared. The stability in biological media, anti-HIV properties and pharmacokinetic parameters in dogs were evaluated. The compounds display moderate anti-HIV activity in cell culture. After oral administration of carbamate IV in dogs, both intact prodrug IV and released AZT were discovered in dog blood. Pharmacokinetic parameters of the compound IV were estimated. Half-life (T(1/2)) of AZT released after oral administration of IV in dogs was close to that after administration of AZT itself, and time to the maximum concentration (T(max)) of AZT released from IV was two and three times longer compared with that of AZT and H-phosphonate AZT, respectively. Acute toxicity was more than five times less if compared with AZT. As a result, we consider this series of carbamate derivatives of AZT as perspective for development of anti-HIV agents.

Design and Synthesis of α-Carboxy Phosphononucleosides

Rhodium catalyzed O-H insertion reactions employing α-diazophosphonate 20 with appropriately protected thymidine, uridine, cytosine, adenosine and guanosine derivatives leads to novel 5'-phosphononucleoside derivatives. Deprotection led to a novel series of phosphono derivatives bearing a carboxylic acid moiety adjacent to the phosphonate group with potential antiviral and/or anticancer activity. The phosphononucleosides bearing an α-carboxylic acid group are envisaged as potential diphosphate mimics. Conversion to mono- and diphosphorylated phosphononucleosides has been effected for evaluation as nucleoside triphosphate mimics. Most of the novel phosphononucleosides proved to be inactive against a variety of DNA and RNA viruses. Only the phosphono AZT derivatives 56-59 showed weak activity against HIV-1 and HIV-2.

ChemInform Abstract: Lipophilic Glycosyl Phosphotriester Derivatives of AZT: Synthesis, NMR Transmembrane Transport Study, and Antiviral Activity.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: One‐Pot Synthesis of 5′‐Diaryl Esters and Diamidates of Phosphate, Phosphorothioate, and Phosphoroselenoate Derivatives of AZT and d4T.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

One-Pot Synthesis of 5′-Diaryl Esters and Diamidates of Phosphate, Phosphorothioate, and Phosphoroselenoate Derivatives of AZT and d4T

Modified nucleosides such as 3′-azido-2′,3′-dideoxythymide (AZT) and 2′,3′-dideoxy-2′,3′-didehydrothymide (d4T) are of importance as antiviral agents and in other medicinal applications. Consequently, there is interest in new analogs of these compounds and in new methods for preparing them. In this article, a simple but efficient, one-pot synthesis of 5′-diaryl esters and diamidates of phosphate, phosphorothioate, and phosphoroselenoate derivatives of AZT and d4T is described. The reaction of AZT/d4T with phosphorus trichloride, followed with phenols, aniline, or amino acid methyl esters in the presence of a base, led to the corresponding tricoordinated phosphite compounds of AZT/d4T, which were then oxidized with 3-chloroperoxybenzoic acid (m-CPBA), sulfur, or selenium powder to finally afford the corresponding target compounds in good yield.

Synthesis and antiretroviral evaluation of derivatives of zidovudine

A series of zidovudine (AZT, 1) derivatives have been synthesized and their anti-HIV activity and cytotoxicity have been determined. The 5'-OH function of AZT was derivatized using N, N'-carbonyldiimidazole and different amine compounds leading to their 5'-O-carbamates. In addition, two known AZT derivatives 5'-O-tosylate and a tricyclic one (AZT-Cycl) were also obtained by a simpler procedure than those previously reported. Although these AZT derivatives were less toxic than AZT, their reduced cytotoxicity was concomitant with an inability to inhibit HIV-1 replication, except in the case of AZT-Cycl, which showed an IC50 = 1 µmol L-1 without cytotoxicity with values of CCID50 ( µmol L-1) > 1000.

5′-Aminocarbonyl Phosphonates as New Zidovudine Depot Forms: Antiviral Properties, Intracellular Transformations, and Pharmacokinetic Parameters

The main disadvantages of 3'-azido-3'-deoxythymidine (zidovudine, AZT), the most common anti-HIV drug, are toxicity and a short half-life in the organism. The introduction of an H-phosphonate group into the AZT 5' position resulted in significant improvement of its therapeutic properties and allowed a new anti-HIV drug, Nikavir (AZT H-phosphonate). In this work, we described a new group of AZT derivatives, namely, AZT 5'-aminocarbonylphosphonates. The synthesized compounds displayed antiviral properties in cell cultures infected with HIV-1 and the capacity to release the active nucleoside in animals (rabbits and dogs) in a dose-dependent manner. The compounds were less toxic in MT-4 and HL-60 cell cultures and experimental animals compared with AZT. Major metabolites found in MT-4 cells after their incubation with AZT 5'-aminocarbonylphosphonate 1 were AZT and AZT 5'-phosphate (25 and 55%, respectively). Among the tested compounds, phosphonate 1 was the most effective AZT donor, and its longest t(1/2) and T(max) values in the line phosphonate 1--AZT H-phosphonate--AZT imply that compound 1 is an extended depot form of AZT. Although bioavailability of AZT after oral administration of phosphonate 1 was lower than those of AZT H-phosphonate and AZT (8 against 14 and 49%), we expect that this reduction would not cause essential decrease of antiviral activity but noticeably decrease toxicity as a result of gradual accumulation of AZT in blood and the absence of sharp difference between C(max) and C(min). Such a combination of properties makes the compounds of this group promising for further studies as extended-release forms of AZT.

A step further in the SATE mononucleotide prodrug approach

Synthesis, in vitro anti-HIV activity, stability studies as well as potential for oral absorption of some novel phenyl S-acyl-2-thioethyl (SATE) phosphotriester derivatives of AZT (zidovudine; 3'-azido-2',3'- dideoxythymidine) are reported herein. These mononucleotide prodrugs (pronucleotides) are characterized by the presence of polar (amino or hydroxyl) functions on the SATE biolabile phosphate protections. Whereas pronucleotides incorporating an amino residue in the vicinity of the thioester functionality display low chemical stability, the introduction of one or two hydroxyl groups on the SATE moiety confers high resistance of the resulting prodrugs towards esterase hydrolysis. Thus, one of these pronucleotides, derivative 2, was able to cross a Caco-2 cell monolayer mainly in intact form, probing that its further development is warranted as a possible HIV-pronucleotide candidate.

Phenyl phosphotriester derivatives of AZT: Variations upon the SATE moiety

Synthesis, in vitro anti-HIV activity, stability studies as well as potential for oral absorption of some novel phenyl S-acyl-2-thioethyl (SATE) phosphotriester derivatives of AZT (zidovudine; 3′-azido-2′,3′-dideoxythymidine) are described herein. These pronucleotides are characterized by the presence of polar functions on the SATE biolabile phosphate protections. Whereas derivatives incorporating an amino residue in the vicinity of the thioester functionality display low chemical stability, the introduction of one or two hydroxyl groups on the SATE moieties confers high resistance of the resulting prodrugs towards esterase hydrolysis. Thus, one of these pronucleotides, the monohydroxylated SATE derivative of AZT 2, is able to cross a Caco-2 cell monolayer mainly in intact form, probing that further development is warranted as a possible HIV-pronucleotide candidate.

Dipeptide Derivatives of AZT: Synthesis, Chemical Stability, Activation in Human Plasma, hPEPT1 Affinity, and Antiviral Activity

5'-O-Dipeptide ester prodrugs of antiviral zidovudine (AZT) were designed to target the human intestinal oligopeptide transporter, hPEPT1, and were evaluated for their stability at pH 7.4 in buffer and in human plasma, affinity toward hPEPT1, cytotoxicity, and antiretroviral activity. The dipeptide esters of AZT undergo cyclization in buffer at pH 7.4 to release the parent drug at a rate that depends on the size of the side chains of the peptide carrier; the prodrug is considerably more stable if bulky beta-branched amino acids such as Ile and Val are present, particularly as C-terminal residues. Incubation in human plasma showed that most of the dipeptide esters of AZT release the parent drug through two aminopeptidase-mediated pathways: 1) stepwise cleavage of each of the amino acids and 2) direct cleavage of the dipeptide-drug ester bond. However, the plasma hydrolysis of Gly-Gly-AZT and Phe-Gly-AZT showed only direct cleavage of the dipeptide-drug ester bond. Substrate half-lives in plasma were again remarkably high when hydrophobic beta-branched amino acids (Val, Ile) were present. The esters were also good substrates for the intestinal oligopeptide transporter hPEPT1 in vitro, with Val-Gly-AZT and Val-Ala-AZT presenting the highest affinity toward the transporter (IC(50): 0.20 and 0.15 mM, respectively). The AZT dipeptide esters were assayed against the IIIB and ROD strains of HIV, and their cytotoxicity was evaluated in MT-4 cells. The selectivity index of the prodrugs was two- to threefold higher than that of AZT for all compounds analyzed. These results point to the potential of dipeptide-based carriers for the development of effective antiviral drug-delivery systems. Val-Ala-AZT appears to combine chemical stability with good affinity for the hPEPT1 transporter and an improved cytotoxicity/antiretroviral index relative to AZT.

Synthesis and anti-HIV activities of phosphate triester derivatives of 3′-fluoro-2′,3′-dideoxythymidine and 3′-azido-2′,3′-dideoxythymidine

Fatty acyl-glycol phosphate triester conjugates of 3′-fluoro-2′,3′-dideoxythymidine (FLT) were prepared in three steps from the reaction of diisopropylphoramidous dichloride with fatty acyl-substituted glycols, followed by a coupling reaction with FLT and oxidation with tert-butyl hydroperoxide ( t-BuOOH). Additionally, a number of fatty alcohols were reacted with diisopropylphoramidous dichloride to produce the phosphitylating intermediates, which underwent coupling reactions with 3′-azido-2′,3′-dideoxythymidine (AZT) and FLT followed by oxidation with t-BuOOH to yield fatty alcohol phosphate triester derivatives of AZT and FLT.

Binding to human serum albumin of zidovudine (AZT) and novel AZT derivatives. Experimental and theoretical analyses☆

This work presents the binding of AZT and nine novel AZT derivatives to human serum albumin (HSA), both defatted (HSA(D)) and complexed with fatty acids (HSA(FA)). The bound fractions and binding site were determined by applying an ultrafiltration procedure, with an increased affinity for the majority of these derivatives to HSA(D) being found with respect to that of AZT, while only one derivative exhibited an increased affinity for HSA(FA). By means of computational methods, we observed that specific electrostatic interactions are responsible for the increased affinity for HSA(D), while the presence of fatty acids complexed to HSA caused an intense electrostatic repulsion with negatively charged ligands located in Sudlow site I, thus diminishing their bound fractions. A strong relationship between the calculated energetic components and the observed experimental affinity was identified.

Separation of 3′-azido-2′,3′-dideoxythymidine pronucleotide diastereoisomers in biological samples by CZE with cyclodextrin addition

The possibility of using capillary electrophoresis as an alternative technique to HPLC for the separation of pronucleotide diastereoisomers of AZT was investigated. In the pH range 6.2–7.2 where the analytes are stable, a chiral additive, carboxymethyl-β-CD, was found appropriate to enable the separation of the uncharged diastereoisomers. An experimental design strategy was used to study the influence of several parameters (CD and phosphate buffer concentration, methanol content of the electrolyte, injected volume, capillary length, electric field and separation temperature) on the separation and find suitable analytical conditions for monitoring the prodrugs in cell extracts. The diastereoisomers of the three tBuSATE phenylphosphotriester derivatives of AZT studied could be fully resolved within short analysis time (less than 10 min). Method validation results showed satisfactory results for linearity, accuracy and repeatability.