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1.
Molecules ; 24(6)2019 Mar 25.
Article in English | MEDLINE | ID: mdl-30934584

ABSTRACT

Metallo-ß-lactamases (MßLs) are the target enzymes of ß-lactam antibiotic resistance, and there are no effective inhibitors against MßLs available for clinic so far. In this study, thirteen halogen-substituted triazolethioacetamides were designed and synthesized as a potent skeleton of MßLs inhibitors. All the compounds displayed inhibitory activity against ImiS with an IC50 value range of 0.032⁻15.64 µM except 7. The chlorine substituted compounds (1, 2 and 3) inhibited NDM-1 with an IC50 value of less than 0.96 µM, and the fluorine substituted 12 and 13 inhibited VIM-2 with IC50 values of 38.9 and 2.8 µM, respectively. However, none of the triazolethioacetamides exhibited activity against L1 at inhibitor concentrations of up to 1 mM. Enzyme inhibition kinetics revealed that 9 and 13 are mixed inhibitors for ImiS with Ki values of 0.074 and 0.27µM using imipenem as the substrate. Docking studies showed that 1 and 9, which have the highest inhibitory activity against ImiS, fit the binding site of CphA as a replacement of ImiS via stable interactions between the triazole group bridging ASP120 and hydroxyl group bridging ASN233.


Subject(s)
Halogens/chemistry , Thioacetamide/chemistry , Thioacetamide/pharmacology , beta-Lactamase Inhibitors/chemistry , beta-Lactamase Inhibitors/pharmacology , beta-Lactamases/chemistry , Binding Sites , Dose-Response Relationship, Drug , Models, Molecular , Molecular Conformation , Molecular Structure , Protein Binding , Structure-Activity Relationship , Thioacetamide/analogs & derivatives
2.
Eur J Med Chem ; 162: 507-524, 2019 Jan 15.
Article in English | MEDLINE | ID: mdl-30472599

ABSTRACT

Second- and third-generation inhibitors of EGFR possess an acrylamide group which alkylates Cys797, allowing to overcome resistance due to insurgence of T790M mutation. Less reactive warheads, yet capable to bind the target cysteine, may be useful to design newer and safer inhibitors. In the present work, we synthesized a 2-chloro-N-(4-(phenylamino)quinazolin-6-yl)acetamide (8) derivative as a prototype of EGFR inhibitor potentially able to react with Cys797 by nucleophilic substitution. We then tuned the reactivity of the acetamide fragment by replacing the chlorine leaving group with (hetero)-aromatic thiols or carboxylate esters. Among the synthesized derivatives, the 2-((1H-imidazol-2-yl)thio)acetamide 16, while showing negligible reactivity with cysteine in solution, caused long-lasting inhibition of wild-type EGFR autophosphorylation in A549 cells, resulted able to bind recombinant EGFR L858R/T790M in a time-dependent manner, and inhibited both EGFR autophosphorylation and proliferation in gefitinib-resistant H1975 lung cancer cells (expressing EGFR L858R/T790M mutant) at low micromolar concentration.


Subject(s)
Antineoplastic Agents/pharmacology , Thioacetamide/pharmacology , A549 Cells , Acetamides/chemistry , Antineoplastic Agents/chemical synthesis , Cell Line, Tumor , Cell Proliferation/drug effects , Cysteine/metabolism , ErbB Receptors/antagonists & inhibitors , Gefitinib/pharmacology , Humans , Lung Neoplasms/drug therapy , Lung Neoplasms/metabolism , Lung Neoplasms/pathology , Phosphorylation , Thioacetamide/analogs & derivatives , Thioacetamide/chemical synthesis
3.
Bioorg Med Chem Lett ; 27(23): 5225-5229, 2017 12 01.
Article in English | MEDLINE | ID: mdl-29122480

ABSTRACT

In an effort to develop new inhibitors of metallo-ß-lactamases (MßLs), twenty-eight azolylthioacetamides were synthesized and assayed against MßLs. The obtained benzimidazolyl and benzioxazolyl substituted 1-19 specifically inhibited the enzyme ImiS, and 10 was found to be the most potent inhibitor of ImiS with an IC50 value of 15 nM. The nitrobenzimidazolyl substituted 20-28 specifically inhibited NDM-1, with 27 being the most potent inhibitor with an IC50 value of 170 nM. Further studies with 10, 11, and 27 revealed a mixed inhibition mode with competitive and uncompetitive inhibition constants in a similar range as the IC50 values. These inhibitors resulted in a 2-4-fold decrease in imipenem MIC values using E. coli cells producing ImiS or NDM-1. While the source of uncompetitive (possibly allosteric) inhibition remains unclear, docking studies indicate that 10 and 11 may interact orthosterically with Zn2 in the active site of CphA, while 27 could bridge the two Zn(II) ions in the active site of NDM-1 via its nitro group.


Subject(s)
Anti-Bacterial Agents/pharmacology , Azoles/pharmacology , Escherichia coli/drug effects , Thioacetamide/analogs & derivatives , beta-Lactamase Inhibitors/pharmacology , beta-Lactamases/metabolism , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Azoles/chemical synthesis , Azoles/chemistry , Dose-Response Relationship, Drug , Escherichia coli/cytology , Escherichia coli/enzymology , Molecular Docking Simulation , Molecular Structure , Structure-Activity Relationship , Thioacetamide/chemical synthesis , Thioacetamide/chemistry , Thioacetamide/pharmacology , beta-Lactamase Inhibitors/chemical synthesis , beta-Lactamase Inhibitors/chemistry
4.
J Cell Biochem ; 118(12): 4672-4685, 2017 12.
Article in English | MEDLINE | ID: mdl-28498494

ABSTRACT

Histone deacetylase inhibitors (HDACIs) have emerged as potential anticancer agents for the treatment of solid and hematopoietic cancers. Several HDACIs delay cell growth, induce differentiation, or activate apoptosis in multiple types of tumors, including glioblastomas. In the present study, we showed that the mercaptoacetamide-based HDACI W2 inhibits cell migration and invasion in monomorphic malignant human glioma cells. W2 treatment significantly decreased the activity and expression levels of matrix metalloprotease-2 in malignant A172 cells but not in U373MG cells. Key signaling pathways involved in cell migration and invasion, including PI3K-AKT, ERK-JNK-P38, and FAK/STAT3, were examined to identify the mechanism of action of W2. W2 increased the phosphorylation of AKT and altered cell migration and invasion in an AKT-independent manner. W2 inhibited the phosphorylation of FAK/STAT3, and treatment with a FAK/STAT3 inhibitor significantly suppressed cancer cell migration and MMP-2 activity in the presence of W2. In addition, W2 significantly inhibited the nuclear translocation of phospho-STAT3. Taken together, our results suggest that W2 suppresses cancer cell migration and invasion by inhibiting FAK/STAT3 signaling and STAT3 translocation to the nucleus in monomorphic malignant human glioma cells. J. Cell. Biochem. 118: 4672-4685, 2017. © 2017 Wiley Periodicals, Inc.


Subject(s)
Cell Movement/drug effects , Focal Adhesion Kinase 1/metabolism , Glioma/drug therapy , Histone Deacetylase Inhibitors/pharmacology , MAP Kinase Signaling System/drug effects , Neoplasm Proteins/metabolism , STAT3 Transcription Factor/metabolism , Thioacetamide/analogs & derivatives , Cell Line, Tumor , Focal Adhesion Kinase 1/genetics , Glioma/genetics , Glioma/metabolism , Glioma/pathology , Humans , Neoplasm Invasiveness , Neoplasm Proteins/genetics , STAT3 Transcription Factor/genetics , Thioacetamide/pharmacology
5.
J Med Chem ; 57(3): 1000-13, 2014 Feb 13.
Article in English | MEDLINE | ID: mdl-24494745

ABSTRACT

2-[(Diphenylmethyl)sulfinyl]acetamide (modafinil, (±)-1) is a unique dopamine uptake inhibitor that binds the dopamine transporter (DAT) differently than cocaine and may have potential for the treatment of psychostimulant abuse. To further investigate structural requirements for this divergent binding mode, novel thio- and sulfinylacetamide and ethanamine analogues of (±)-1 were synthesized wherein (1) the diphenyl rings were substituted with methyl, trifluoromethyl, and halogen substituents and (2) substituents were added to the terminal amide/amine nitrogen. Halogen substitution of the diphenyl rings of (±)-1 gave several amide analogues with improved binding affinity for DAT and robust selectivity over the serotonin transporter (SERT), whereas affinity improved at SERT over DAT for the p-halo-substituted amine analogues. Molecular docking studies, using a subset of analogues with DAT and SERT homology models, and functional data obtained with DAT (A480T) and SERT (T497A) mutants defined a role for TM10 in the substrate/inhibitor S1 binding sites of DAT and SERT.


Subject(s)
Benzhydryl Compounds/chemical synthesis , Dopamine Plasma Membrane Transport Proteins/metabolism , Norepinephrine Plasma Membrane Transport Proteins/metabolism , Serotonin Plasma Membrane Transport Proteins/metabolism , Animals , Benzhydryl Compounds/chemistry , Benzhydryl Compounds/pharmacology , Binding Sites , Brain/metabolism , COS Cells , Chlorocebus aethiops , Dopamine Plasma Membrane Transport Proteins/chemistry , Dopamine Plasma Membrane Transport Proteins/genetics , Male , Modafinil , Molecular Docking Simulation , Mutation , Norepinephrine Plasma Membrane Transport Proteins/chemistry , Norepinephrine Plasma Membrane Transport Proteins/genetics , Protein Binding , Radioligand Assay , Rats , Rats, Sprague-Dawley , Serotonin Plasma Membrane Transport Proteins/chemistry , Serotonin Plasma Membrane Transport Proteins/genetics , Stereoisomerism , Structure-Activity Relationship , Thioacetamide/analogs & derivatives , Thioacetamide/chemical synthesis , Thioacetamide/chemistry , Thioacetamide/pharmacology
6.
Chem Res Toxicol ; 26(4): 564-74, 2013 Apr 15.
Article in English | MEDLINE | ID: mdl-23465048

ABSTRACT

Thioacetamide (TA) has long been known as a hepatotoxicant whose bioactivation requires S-oxidation to thioacetamide S-oxide (TASO) and then to the very reactive S,S-dioxide (TASO2). The latter can tautomerize to form acylating species capable of covalently modifying cellular nucleophiles including phosphatidylethanolamine (PE) lipids and protein lysine side chains. Isolated hepatocytes efficiently oxidize TA to TASO but experience little covalent binding or cytotoxicity because TA is a very potent inhibitor of the oxidation of TASO to TASO2. However, hepatocytes treated with TASO show extensive covalent binding to both lipids and proteins accompanied by extensive cytotoxicity. In this work, we treated rat hepatocytes with [(14)C]-TASO and submitted the mitochondrial, microsomal, and cytosolic fractions to 2DGE, which revealed a total of 321 radioactive protein spots. To facilitate the identification of target proteins and adducted peptides, we also treated cells with a mixture of TASO/[(13)C2D3]-TASO. Using a combination of 1DGE- and 2DGE-based proteomic approaches, we identified 187 modified peptides (174 acetylated, 50 acetimidoylated, and 37 in both forms) from a total of 88 nonredundant target proteins. Among the latter, 57 are also known targets of at least one other hepatotoxin. The formation of both amide- and amidine-type adducts to protein lysine side chains is in contrast to the exclusive formation of amidine-type adducts with PE phospholipids. Thiobenzamide (TB) undergoes the same two-step oxidative bioactivation as TA, and it also gives rise to both amide and amidine adducts on protein lysine side chains but only amidine adducts to PE lipids. Despite their similarity in functional group chemical reactivity, only 38 of 62 known TB target proteins are found among the 88 known targets of TASO. The potential roles of protein modification by TASO in triggering cytotoxicity are discussed in terms of enzyme inhibition, protein folding, and chaperone function, and the emerging role of protein acetylation in intracellular signaling and the regulation of biochemical pathways.


Subject(s)
Hepatocytes/drug effects , Proteins/metabolism , Thioacetamide/analogs & derivatives , Animals , Cells, Cultured , Cytosol/drug effects , Cytosol/metabolism , Hepatocytes/metabolism , Male , Microsomes, Liver/drug effects , Microsomes, Liver/metabolism , Mitochondria, Liver/drug effects , Mitochondria, Liver/metabolism , Proteomics , Rats , Rats, Sprague-Dawley , Thioacetamide/toxicity
7.
Chem Res Toxicol ; 25(9): 1955-63, 2012 Sep 17.
Article in English | MEDLINE | ID: mdl-22867114

ABSTRACT

The hepatotoxicity of thioacetamide (TA) has been known since 1948. In rats, single doses cause centrolobular necrosis accompanied by increases in plasma transaminases and bilirubin. To elicit these effects, TA requires oxidative bioactivation, leading first to its S-oxide (TASO) and then to its chemically reactive S,S-dioxide (TASO(2)), which ultimately modifies amine-lipids and proteins. To generate a suite of liver proteins adducted by TA metabolites for proteomic analysis and to reduce the need for both animals and labeled compounds, we treated isolated hepatocytes directly with TA. Surprisingly, TA was not toxic at concentrations up to 50 mM for 40 h. On the other hand, TASO was highly toxic to isolated hepatocytes as indicated by LDH release, cellular morphology, and vital staining with Hoechst 33342/propidium iodide. TASO toxicity was partially blocked by the CYP2E1 inhibitors diallyl sulfide and 4-methylpyrazole and was strongly inhibited by TA. Significantly, we found that hepatocytes produce TA from TASO relatively efficiently by back-reduction. The covalent binding of [(14)C]-TASO is inhibited by unlabeled TA, which acts as a "cold-trap" for [(14)C]-TA and prevents its reoxidation to [(14)C]-TASO. This in turn increases the net consumption of [(14)C]-TASO despite the fact that its oxidation to TASO(2) is inhibited. The potent inhibition of TASO oxidation by TA, coupled with the back-reduction of TASO and its futile redox cycling with TA, may help explain phenomena previously interpreted as "saturation toxicokinetics" in the in vivo metabolism and toxicity of TA and TASO. The improved understanding of the metabolism and covalent binding of TA and TASO facilitates the use of hepatocytes to prepare protein adducts for target protein identification.


Subject(s)
Hepatocytes/metabolism , Thioacetamide/analogs & derivatives , Thioacetamide/metabolism , Animals , Cells, Cultured , Cytochrome P-450 CYP2E1/metabolism , Cytochrome P-450 CYP2E1 Inhibitors , Hepatocytes/drug effects , L-Lactate Dehydrogenase/metabolism , Male , Rats , Rats, Sprague-Dawley , Thioacetamide/toxicity
8.
Arch Pharm Res ; 35(6): 975-86, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22870806

ABSTRACT

In continuation of our endeavor to develop new, potent, selective and less toxic antiviral agents, a novel series of 2-(2-amino/chloro-4-(2,4-dibromophenyl) thiazol-5-ylthio)acetamide derivatives was synthesized via an expeditious route and evaluated for their anti-HIV activities against wild-type virus and clinically relevant mutant strains, and for their anti-influenza virus activities against influenza A (H1N1 and H3N2) and influenza B in cellular assays. The selected active compounds were also assayed for their enzymic inhibitory activities. The results showed that some 2-chloro substituted thiazolylthioacetamide derivatives possessed potent activity against wild type HIV-1 and several key mutant strains (E138K, K103N, L100I) of HIV-1 in MT-4 cells with EC(50) values in micromolar range. Two 2-amino substituted thiazole derivatives 8a7 and 8a8 displayed significant potency against influenza A/H1N1 in MDCK cells with EC(50) values much lower than that of oseltamivir carboxylate, ribavirin, amantadine and rimantadine. Though the mechanism of actions is still unclear, these novel thiazolylthioacetamides might serve as original leads for further pharmacological investigations as potential therapeutic agents against HIV-1 or influenza virus.


Subject(s)
Antiviral Agents/chemical synthesis , Antiviral Agents/pharmacology , Thioacetamide/chemical synthesis , Thioacetamide/pharmacology , Animals , Anti-HIV Agents/chemical synthesis , Anti-HIV Agents/pharmacology , Chick Embryo , Dogs , Dose-Response Relationship, Drug , HIV Reverse Transcriptase/antagonists & inhibitors , HIV Reverse Transcriptase/metabolism , HIV-1/drug effects , HIV-1/enzymology , HIV-1/genetics , HIV-1/growth & development , Influenza A Virus, H1N1 Subtype/drug effects , Influenza A Virus, H1N1 Subtype/enzymology , Influenza A Virus, H1N1 Subtype/growth & development , Influenza A Virus, H3N2 Subtype/drug effects , Influenza A Virus, H3N2 Subtype/growth & development , Influenza B virus/drug effects , Influenza B virus/growth & development , Inhibitory Concentration 50 , Madin Darby Canine Kidney Cells , Molecular Structure , Mutation , Neuraminidase/antagonists & inhibitors , Neuraminidase/metabolism , Reverse Transcriptase Inhibitors/chemical synthesis , Reverse Transcriptase Inhibitors/pharmacology , Structure-Activity Relationship , Thioacetamide/analogs & derivatives
9.
Proc Natl Acad Sci U S A ; 109(37): E2476-85, 2012 Sep 11.
Article in English | MEDLINE | ID: mdl-22895790

ABSTRACT

Up-regulation of the folding machinery of the heat-shock protein 90 (Hsp90) chaperone protein is crucial for cancer progression. The two Hsp90 isoforms (α and ß) play different roles in response to chemotherapy. To identify isoform-selective inhibitors of Hsp90(α/ß)/cochaperone p23 interactions, we developed a dual-luciferase (Renilla and Firefly) reporter system for high-throughput screening (HTS) and monitoring the efficacy of Hsp90 inhibitors in cell culture and live mice. HTS of a 30,176 small-molecule chemical library in cell culture identified a compound, N-(5-methylisoxazol-3-yl)-2-[4-(thiophen-2-yl)-6-(trifluoromethyl)pyrimidin-2-ylthio]acetamide (CP9), that binds to Hsp90(α/ß) and displays characteristics of Hsp90 inhibitors, i.e., degradation of Hsp90 client proteins and inhibition of cell proliferation, glucose metabolism, and thymidine kinase activity, in multiple cancer cell lines. The efficacy of CP9 in disrupting Hsp90(α/ß)/p23 interactions and cell proliferation in tumor xenografts was evaluated by non-invasive, repetitive Renilla luciferase and Firefly luciferase imaging, respectively. At 38 h posttreatment (80 mg/kg × 3, i.p.), CP9 led to selective disruption of Hsp90α/p23 as compared with Hsp90ß/p23 interactions. Small-animal PET/CT in the same cohort of mice showed that CP9 treatment (43 h) led to a 40% decrease in (18)F-fluorodeoxyglucose uptake in tumors relative to carrier control-treated mice. However, CP9 did not lead to significant degradation of Hsp90 client proteins in tumors. We performed a structural activity relationship study with 62 analogs of CP9 and identified A17 as the lead compound that outperformed CP9 in inhibiting Hsp90(α/ß)/p23 interactions in cell culture. Our efforts demonstrated the power of coupling of HTS with multimodality molecular imaging and led to identification of Hsp90 inhibitors.


Subject(s)
Acetamides/pharmacology , Benzoquinones/pharmacology , HSP90 Heat-Shock Proteins/metabolism , Intramolecular Oxidoreductases/metabolism , Lactams, Macrocyclic/pharmacology , Neoplasms/metabolism , Thioacetamide/analogs & derivatives , Thiophenes/pharmacology , Animals , Blotting, Western , Cell Line, Tumor , Drug Discovery , HSP90 Heat-Shock Proteins/antagonists & inhibitors , High-Throughput Screening Assays , Humans , Imidazoles , Immunoprecipitation , Lead/pharmacology , Luciferases, Firefly , Luciferases, Renilla , Mice , Mice, Nude , Neoplasms/drug therapy , Positron-Emission Tomography , Prostaglandin-E Synthases , Protein Folding , Protein Isoforms/metabolism , Pyrazines , Small Molecule Libraries , Thioacetamide/pharmacology , Tomography, X-Ray Computed , Tritium
10.
Chem Res Toxicol ; 25(9): 1868-77, 2012 Sep 17.
Article in English | MEDLINE | ID: mdl-22667464

ABSTRACT

Thioacetamide (TA) is a well-known hepatotoxin in rats. Acute doses cause centrilobular necrosis and hyperbilirubinemia while chronic administration leads to biliary hyperplasia and cholangiocarcinoma. Its acute toxicity requires its oxidation to a stable S-oxide (TASO) that is oxidized further to a highly reactive S,S-dioxide (TASO(2)). To explore possible parallels among the metabolism, covalent binding, and toxicity of TA and thiobenzamide (TB), we exposed freshly isolated rat hepatocytes to [(14)C]-TASO or [(13)C(2)D(3)]-TASO. TLC analysis of the cellular lipids showed a single major spot of radioactivity that mass spectral analysis showed to consist of N-acetimidoyl PE lipids having the same side chain composition as the PE fraction from untreated cells; no carbons or hydrogens from TASO were incorporated into the fatty acyl chains. Many cellular proteins contained N-acetyl- or N-acetimidoyl lysine residues in a 3:1 ratio (details to be reported separately). We also oxidized TASO with hydrogen peroxide in the presence of dipalmitoyl phosphatidylenthanolamine (DPPE) or lysozyme. Lysozyme was covalently modified at five of its six lysine side chains; only acetamide-type adducts were formed. DPPE in liposomes also gave only amide-type adducts, even when the reaction was carried out in tetrahydrofuran with only 10% water added. The exclusive formation of N-acetimidoyl PE in hepatocytes means that the concentration or activity of water must be extremely low in the region where TASO(2) is formed, whereas at least some of the TASO(2) can hydrolyze to acetylsulfinic acid before it reacts with cellular proteins. The requirement for two sequential oxidations to produce a reactive metabolite is unusual, but it is even more unusual that a reactive metabolite would react with water to form a new compound that retains a high degree of chemical reactivity toward biological nucleophiles. The possible contribution of lipid modification to the hepatotoxicity of TA/TASO remains to be determined.


Subject(s)
Muramidase/chemistry , Phosphatidylethanolamines/chemistry , Thioacetamide/metabolism , Animals , Cells, Cultured , Chromatography, Thin Layer , Hepatocytes/cytology , Hepatocytes/drug effects , Hepatocytes/metabolism , Male , Mass Spectrometry , Muramidase/metabolism , Oxidation-Reduction , Phosphatidylethanolamines/metabolism , Rats , Rats, Sprague-Dawley , Thioacetamide/analogs & derivatives , Thioacetamide/chemistry , Thioacetamide/toxicity
11.
Molecules ; 17(1): 1025-38, 2012 Jan 19.
Article in English | MEDLINE | ID: mdl-22262201

ABSTRACT

New derivatives of 7-aminocephalosporanic acid 1-8 were synthesized by acylation of the 7-amino group of the cephem nucleus with various arylidinimino-1,3,4-thiadiazole-thio(or dithio)-acetic acid intermediates 3a-d and 5a-d, respectively, so the acyl side chains of these new cephalosporins contained a sulfide or disulfide bond. This unique combination of a Schiff base with the sulfide or disulfide bonds in the acyl side chain afforded new cephalosporins of reasonable potencies, some of which were found to possess moderate activities against the tested microorganisms. Their chemical structures were characterized by ¹H-NMR, IR spectroscopy and elemental microanalysis. Preliminary in vitro antimicrobial activities of the prepared cephalosporins were investigated using a panel of selected microorganisms. Results indicated that the newly synthesized cephalosporins containing disulfide bonds (compounds 5-8) exhibited better activities against Staphylococcus aureus and Escherichia coli. The cephalosporins cross-linked by a sulfide bond (compounds 1-4) showed a slight change in antimicrobial activities when compared with that of the reference cephalosporin (cephalexin).


Subject(s)
Anti-Bacterial Agents/chemical synthesis , Cephalosporins/chemical synthesis , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Cephalosporins/chemistry , Cephalosporins/pharmacology , Disulfides/chemical synthesis , Disulfides/chemistry , Disulfides/pharmacology , Escherichia coli/drug effects , Microbial Sensitivity Tests , Molecular Structure , Schiff Bases/chemical synthesis , Schiff Bases/chemistry , Schiff Bases/pharmacology , Spectrophotometry, Infrared , Staphylococcus aureus/drug effects , Thiadiazoles/chemical synthesis , Thiadiazoles/chemistry , Thiadiazoles/pharmacology , Thioacetamide/analogs & derivatives , Thioacetamide/chemical synthesis , Thioacetamide/pharmacology , Transition Temperature
12.
Nat Biotechnol ; 30(2): 179-83, 2012 Jan 15.
Article in English | MEDLINE | ID: mdl-22252509

ABSTRACT

Drug-induced liver injury (DILI) limits the development and application of many therapeutic compounds and presents major challenges to the pharmaceutical industry and clinical medicine. Acetaminophen-containing compounds are among the most frequently prescribed drugs and are also the most common cause of DILI. Here we describe a pharmacological strategy that targets gap junction communication to prevent amplification of fulminant hepatic failure and acetaminophen-induced hepatotoxicity. We demonstrate that connexin 32 (Cx32), a key hepatic gap junction protein, is an essential mediator of DILI by showing that mice deficient in Cx32 are protected against liver damage, acute inflammation and death caused by liver-toxic drugs. We identify a small-molecule inhibitor of Cx32 that protects against liver failure and death in wild-type mice when co-administered with known hepatotoxic drugs. These findings indicate that gap junction inhibition could provide a pharmaceutical strategy to limit DILI and improve drug safety.


Subject(s)
Acetaminophen/adverse effects , Boron Compounds/administration & dosage , Chemical and Drug Induced Liver Injury/metabolism , Connexins/antagonists & inhibitors , Connexins/metabolism , Gap Junctions/drug effects , Gap Junctions/metabolism , Protective Agents/administration & dosage , Acetaminophen/analogs & derivatives , Acetaminophen/therapeutic use , Animals , Chemical and Drug Induced Liver Injury/prevention & control , Connexins/deficiency , HeLa Cells , Humans , Liver Failure, Acute/chemically induced , Liver Failure, Acute/prevention & control , Mice , Mice, Inbred C57BL , Thioacetamide/administration & dosage , Thioacetamide/adverse effects , Thioacetamide/analogs & derivatives , Gap Junction beta-1 Protein
13.
Bioorg Med Chem ; 18(2): 605-11, 2010 Jan 15.
Article in English | MEDLINE | ID: mdl-20036560

ABSTRACT

Inhibitors of histone deacetylases (HDAC) are emerging as a promising class of anti-cancer agents. The mercaptoacetoamide-based inhibitors are reported to be less toxic than hydroxamate and are worthy of further consideration. Therefore, we have designed a series of analogs as potential inhibitors of HDACs, in which the mercaptoacetamide group was replaced by (mercaptomethyl)fluoroalkene, and their HDAC inhibitory activity was evaluated. Subnanomolar inhibition was observed for all synthetic compounds.


Subject(s)
Histone Deacetylase Inhibitors/pharmacology , Hydrocarbons, Fluorinated/chemistry , Thioacetamide/pharmacology , Drug Design , HeLa Cells , Histone Deacetylase Inhibitors/chemical synthesis , Histone Deacetylase Inhibitors/chemistry , Humans , Molecular Structure , Stereoisomerism , Structure-Activity Relationship , Thioacetamide/analogs & derivatives , Thioacetamide/chemistry
14.
Bioorg Med Chem ; 17(8): 3072-9, 2009 Apr 15.
Article in English | MEDLINE | ID: mdl-19329331

ABSTRACT

Botulinum neurotoxin elicits its paralytic activity through a zinc-dependant metalloprotease that cleaves proteins involved in neurotransmitter release. Currently, no drugs are available to reverse the effects of botulinum intoxication. Herein we report the design of a novel series of mercaptoacetamide small-molecule inhibitors active against botulinum neurotoxin serotype A. These analogs show low micromolar inhibitory activity against the isolated enzyme. Structure-activity relationship studies for a series of mercaptoacetamide analogs of 5-amino-3-phenylpyrazole reveal components essential for potent inhibitory activity.


Subject(s)
Botulinum Antitoxin/pharmacology , Botulinum Toxins, Type A/antagonists & inhibitors , Binding Sites , Botulinum Antitoxin/chemistry , Botulinum Toxins, Type A/metabolism , Drug Design , Inhibitory Concentration 50 , Magnetic Resonance Spectroscopy , Structure-Activity Relationship , Sulfhydryl Compounds/chemistry , Sulfhydryl Compounds/pharmacology , Thioacetamide/analogs & derivatives , Thioacetamide/chemistry , Thioacetamide/pharmacology
15.
Acta Crystallogr C ; 64(Pt 11): o599-603, 2008 Nov.
Article in English | MEDLINE | ID: mdl-18989088

ABSTRACT

Molecules of the title compounds, 3'-methylacetanilide [or N-(m-tolyl)acetamide], C(9)H(11)NO, (I), and N-benzylthioacetamide, C(9)H(11)NS, (II), are connected by a framework of intermolecular N-H...O and N-H...S hydrogen bonds, respectively, forming chains with the graph-set description C(4), which run along the b axis. Analyses of the crystal structures of (I) and (II) are helpful in the elucidation of a generation mechanism of the IR spectra of hydrogen-bonded molecular crystals. The correlation between the IR spectra of studied compounds and structural data is also discussed.


Subject(s)
Acetanilides/chemistry , Cold Temperature , Thioacetamide/analogs & derivatives , Crystallography, X-Ray , Hydrogen Bonding , Molecular Structure , Spectroscopy, Fourier Transform Infrared , Thioacetamide/chemistry
16.
Biochemistry ; 47(34): 8866-73, 2008 Aug 26.
Article in English | MEDLINE | ID: mdl-18680312

ABSTRACT

Prion diseases are fatal neurodegenerative disorders believed to be transmitted by PrP (Sc), an aberrant form of the membrane protein PrP (C). In the absence of an established form-specific covalent difference, the infectious properties of PrP (Sc) were uniquely ascribed to the self-perpetuation properties of its aberrant fold. Previous sequencing of the PrP chain isolated from PrP(27-30) showed the oxidation of some methionine residues; however, at that time, these findings were ascribed to experimental limitations. Using the unique recognition properties of alphaPrP mAb IPC2, protein chemistry, and state of the art mass spectrometry, we now show that while a large fraction of the methionine residues in brain PrP (Sc) are present as methionine sulfoxides this modification could not be found on brain PrP (C) as well as on its recombinant models. In particular, the pattern of oxidation of M213 with respect to the glycosylation at N181 of PrP (Sc) differs both within and between species, adding another diversity factor to the structure of PrP (Sc) molecules. Our results pave the way for the production of prion-specific reagents in the form of antibodies against oxidized PrP chains which can serve in the development of both diagnostic and therapeutic strategies. In addition, we hypothesize that the accumulation of PrP (Sc) and thereafter the pathogenesis of prion disease may result from the poor degradation of oxidized aberrantly folded PrP.


Subject(s)
Methionine/analogs & derivatives , PrPSc Proteins/metabolism , Animals , Antibodies, Monoclonal/immunology , Blotting, Western , Brain/metabolism , Cattle , Cricetinae , Electrophoresis, Polyacrylamide Gel , Endopeptidase K/metabolism , Enzyme-Linked Immunosorbent Assay , Epitopes/chemistry , Epitopes/immunology , Humans , Hydrogen Peroxide/pharmacology , Methionine/chemistry , Methionine/metabolism , Mice , Mice, Inbred C57BL , Models, Biological , Oxidation-Reduction/drug effects , PrPC Proteins/chemistry , PrPC Proteins/metabolism , PrPSc Proteins/chemistry , PrPSc Proteins/immunology , Sheep , Tandem Mass Spectrometry , Thioacetamide/analogs & derivatives , Thioacetamide/chemistry
17.
Toxicology ; 230(2-3): 105-16, 2007 Feb 12.
Article in English | MEDLINE | ID: mdl-17187915

ABSTRACT

Thioacetamide (TA) is bioactivated by CYP2E1 to TA sulfoxide (TASO), and to the highly reactive sulfdioxide (TASO(2)), which initiates hepatic necrosis by covalent binding. Previously, we have established that TA exhibits saturation toxicokinetics over a 12-fold dose range, which explains the lack of dose-response for bioactivation-based liver injury. In vivo and in vitro studies indicated that the second step (TASO-->TASO(2)) of TA bioactivation is less efficient than the first one (TA-->TASO). The objective of the present study was to specifically test the saturation of the second step of TA bioactivation by directly administering TASO, which obviates the contribution from first step, i.e. TA-->TASO. Male SD rats were injected with low (50mg/kg, ip), medium (100mg/kg) and high (LD(70), 200mg/kg) doses of TASO. Bioactivation-mediated liver injury that occurs in the initial time points (6 and 12h), estimated by plasma ALT, AST and liver histopathology over a time course, was not dose-proportional. Escalation of liver injury thereafter was dose dependent: low dose injury subsided; medium dose injury escalated upto 36h before declining; high dose injury escalated from 24h leading to 70% mortality. TASO was quantified in plasma by HPLC at various time points after administration of the three doses. With increasing dose (i.e., from 50 to 200mg/kg), area under the curve (AUC) and C(max) increased more than dose proportionately, indicating that TASO bioactivation exhibits saturable kinetics. Toxicokinetics and initiation of liver injury of TASO are similar to that of TA, although TASO-initiated injury occurs at lower doses. These findings indicate that bioactivation of TASO to its reactive metabolite is saturable in the rat as suggested by previous studies with TA.


Subject(s)
Liver/drug effects , Thioacetamide/analogs & derivatives , Alanine Transaminase/blood , Animals , Area Under Curve , Aspartate Aminotransferases/blood , Chemical and Drug Induced Liver Injury/etiology , Chemical and Drug Induced Liver Injury/metabolism , DNA Replication/drug effects , Dose-Response Relationship, Drug , Histocytochemistry , Liver/pathology , Male , Microsomes, Liver/drug effects , Microsomes, Liver/metabolism , Rats , Rats, Sprague-Dawley , Thioacetamide/blood , Thioacetamide/metabolism , Thioacetamide/pharmacokinetics , Thioacetamide/toxicity , Thioacetamide/urine , Thymidine/metabolism
18.
J Phys Chem A ; 110(40): 11473-8, 2006 Oct 12.
Article in English | MEDLINE | ID: mdl-17020259

ABSTRACT

Time-resolved infrared spectroscopy was used to study the photoisomerization of N-Methylthioacetamide (NMTAA) in D2O in both the cis-->trans and the trans-->cis direction upon selective excitation of the n-pi (S1) and pi-pi (S2) electronic transitions. While isomerization and the return to the ground state takes place on two distinct time scales (cis isomerization is 30-40%, independent of the electronic state excited, while the cis-->trans isomerization proceeds with a 60-70% quantum efficiency. These results support a mechanism by which isomerization takes place via one common intermediate state independent of electronic excitation energy and initial conformation.


Subject(s)
Thioacetamide/analogs & derivatives , Isomerism , Photochemistry , Spectrophotometry, Infrared , Thioacetamide/chemistry , Time Factors
19.
J Phys Chem B ; 109(10): 4770-5, 2005 Mar 17.
Article in English | MEDLINE | ID: mdl-16851560

ABSTRACT

A series of thioxo compounds, thioacetamide, N-methylthioacetamide, a cyclic thioxoamide [(S)-5-thioxopyrrolidine-2-carboxylic acid ethyl ester], two thioxylated dipeptides (Ala-Psi[CS-NH]-Ala and Phe-Psi[CS-NH]-Ala) and a thioxylated dodecapeptide (Lys-Glu-Thr-Ala-Ala-Ala-Lys-Phe-Glu-Arg-Gln-His-Psi[CS-NH]-Nle-Asp-Ser-Ser-Thr-Ser-Ala-Ala, or [thioxo-His(12)]-S-peptide; Nle = norleucine) are investigated by ultrafast spectroscopy in the visible and near UV. The different molecules show very similar absorption dynamics featuring a rise of a strong visible absorption band on the subpicosecond and picosecond time scale. The decay of the visible absorption occurs within 150-600 ps. The observations are interpreted by the ultrafast formation of triplet states and their decay on the subnanosecond time scale. Comparison with published IR experiments on N-methylthioacetamide indicates that the cis-trans isomerization around the thioxopeptide bond is terminated within less than 1 ns.


Subject(s)
Amides/chemistry , Peptides/chemistry , Sulfhydryl Compounds/chemistry , Data Interpretation, Statistical , Photochemistry , Spectrophotometry, Ultraviolet , Thioacetamide/analogs & derivatives , Thioacetamide/chemistry
20.
Proteomics ; 4(12): 3960-74, 2004 Dec.
Article in English | MEDLINE | ID: mdl-15526343

ABSTRACT

Thioacetamide (TAA) administration is an established technique for generating rat models of liver fibrosis and cirrhosis. Oxidative stress is believed to be involved as TAA-induced liver fibrosis is initiated by thioacetamide S-oxide, which is derived from the biotransformation of TAA by the microsomal flavine-adenine dinucleotide (FAD)-containing monooxygense (FMO) and cytochrome P450 systems. A two-dimensional gel electrophoresis-mass spectrometry approach was applied to analyze the protein profiles of livers of rats administered with sublethal doses of TAA for 3, 6 and 10 weeks respectively. With this approach, 59 protein spots whose expression levels changed significantly upon TAA administration were identified, including three novel proteins. These proteins were then sorted according to their common biochemical properties and functions, so that pathways involved in the pathogenesis of rat liver fibrosis due to TAA-induced toxicity could be elucidated. As a result, it was found that TAA-administration down-regulated the enzymes of the primary metabolic pathways such as fatty acid beta-oxidation, branched chain amino acids and methionine breakdown. This phenomenon is suggestive of the depletion of succinyl-CoA which affects heme and iron metabolism. Up-regulated proteins, on the other hand, are related to oxidative stress and lipid peroxidation. Finally, these proteomics data and the data obtained from the scientific literature were integrated into an "overview model" for TAA-induced liver cirrhosis. This model could now serve as a useful resource for researchers working in the same area.


Subject(s)
Liver Cirrhosis/chemically induced , Liver/drug effects , Proteomics/methods , Thioacetamide/analogs & derivatives , Thioacetamide/toxicity , Animals , Down-Regulation , Fatty Acids/metabolism , Ferritins/chemistry , Fibrosis , Glutathione/metabolism , Heme/chemistry , Humans , Image Processing, Computer-Assisted , Iron/metabolism , Lipid Peroxidation , Liver/metabolism , Methionine/metabolism , Oxidative Stress , Oxygenases/chemistry , Rats , Rats, Wistar , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization , Thioacetamide/pharmacology , Time Factors , Trypsin/pharmacology , Up-Regulation
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