Synthesis and anti-cancer activities of new sulfonamides 4-substituted-triazolyl nucleosides.

Nucleoside analogues are among the most known drugs commonly used in antiviral and anticancer chemotherapies. Among them, those featuring a five-membered ring nucleobase are of utmost interest such as the anti-cancer agent AICAR or the anti-viral drug ribavirin. Despite its low activity in vitro in different cell lines, AICAR is under clinical development for several pathologies, thanks to its original mode of action. Indeed, AICAR induced autophagy cell death and is able, following this mechanism, to circumvent resistance to apoptotic drugs including kinase inhibitors currently on the market. To improve the activity of AICAR, we report herein an efficient synthesis of new series of sulfonamide-4-substituted-1,2,3-triazolyl nucleosides using a Cu-catalyzed 1,3-dipolar cycloaddition. All these molecules have been fully characterized and evaluated against two aggressive tumor cell lines, RCC4 and MDA-MB-231. Among them, nucleoside analogue 5i belonging to the ribose series was found to be 19 to 66-fold more active than AICAR. Western blot analyses on RCC4 cells showed that 5i displayed an interesting mode of action by inducing both apoptosis and autophagy cell death, making therefore this class of molecules highly promising for further hit-to-lead optimization.

Design, Synthesis, and Biological Evaluation of Novel PARP-1 Inhibitors Based on a 1H-Thieno[3,4-d] Imidazole-4-Carboxamide Scaffold.

A series of poly(ADP-ribose)polymerase (PARP)-1 inhibitors containing a novel scaffold, the 1H-thieno[3,4-d]imidazole-4-carboxamide moiety, was designed and synthesized. These efforts provided some compounds with relatively good PARP-1 inhibitory activity, and among them, 16l was the most potent one. Cellular evaluations indicated that the anti-proliferative activities of 16g, 16i, 16j and 16l against BRCA-deficient cell lines were similar to that of olaparib, while the cytotoxicities of 16j and 16l toward human normal cells were lower. In addition, ADMET prediction results indicated that these compounds might possess more favorable toxicity and pharmacokinetic properties. This study provides a basis for our further investigation.

New synthetic AICAR derivatives with enhanced AMPK and ACC activation.

5-Aminoimidazole-4-carboxamide riboside (AICAR) has an important role in the regulation of the cellular metabolism showing a broad spectrum of therapeutic activities against different metabolic processes. Due to these proven AICAR properties, we have designed, synthesized and tested the biological activity of two ribose-modified AICAR derivatives, named A3 and A4, in comparison to native AICAR and its 5'-phosphorylated counterpart ZMP. Our findings have shown that A3 and A4 derivatives induce the phosphorylation of 5'-AMP activated protein kinase α (AMPKα), which leads to the inhibition of acetyl-CoA carboxylase (ACC), and down-regulate the activity of the extracellular signal-regulated kinases (ERK1/2). Cytotoxicity tests demonstrated that A3 and A4 do not significantly reduce cell viability up to 24 h. Taken together our results indicate that A3 and A4 have a comparable activity to AICAR and ZMP at 0.5 and 1 mM suggesting their potential use in future pharmacological strategies relating to metabolic diseases.

Eficiência do fungicida do grupo químico das carboxamida + estrobilurina no controle da ferrugem asiática em diferentes estádios da soja / Efficiency of fungicide from the carboxamide + strobilurin chemical group in the control of asian rust in different soybean stages / Eficiencia del fungicida del grupo químico de carboxamida + estrobilurina en el control de la oxidación asiática en diferentes etapas de soya

Para estabelecer o momento adequado da aplicação do fungicida no controle da ferrugem asiática (Phakospsora pachyrhizi) da soja, avaliou-se o estádio de aplicação do fungicida do grupo químico carboxamida + estrobirulina (ELATUS®), sob condições de campo. O delineamento experimental foi em blocos casualizados com oito tratamentos e quatro repetições. Cada bloco foi formado por quatro linhas de cinco metros de comprimento com área total de 9 m². Os tratamentos foram: T1 - uma aplicação no estádio V5; T2 - uma aplicação no estádio R1; T3 - uma aplicação no estádio R3; T4 - uma aplicação no estádio R5; T5 - duas aplicações, uma no estádio V5 e uma 21 dias após a primeira (DAA1); T6 - duas aplicações, uma no estádio R1 e uma a 21 DAA1; T7 - três aplicações; uma no estádio V5, a segunda 21 DAA1 e a terceira 21 DAA2 e T8 - Testemunha (controle). A partir dos estudos realizados foi avaliado o índice de severidade da doença, o número de plantas m-1, a massa de mil grãos e o rendimento de grãos. As médias observadas foram submetidas à análise de variância (ANOVA) e teste de Duncan (p ≤ 0,05). Os resultados obtidos mostraram diferenças significativas na severidade da doença, peso de mil grãos e no rendimento. Os tratamentos que apresentaram a menor severidade e maior rendimento de grãos foram T5 e T6 com duas aplicações no estádio V5 e 21 DAA e R1 e 21 DAA. Recomenda-se a aplicação do fungicida ELATUS® em duas vezes, sendo uma no estádio V5 e 21 dias após ou uma no estádio R1 e outra 21 dias após, procedimento esses que mostrou uma boa eficiência no controle do fungo e aumento no rendimento de grãos.

The purpose of this study was to establish the best moment for applying fungicide in the control of Asian rust (Phakospsora pachyrhizi) in soybean. In order to do so, the application stage of the fungicide from the carboxamide + strobirulin chemical group (ELATUS®) was assessed under field conditions. A randomized block experimental design with eight treatments and four replications was used. Each block was formed by four lines of five meters in length with a total area of 9 m². The treatments were: T1 - one application at the V5 stage; T2 - on application at the R1 stage; T3 - one application at the R3 stage; T4 - one application at the R5 stage; T5 - two applications, one at V5 and the other, 21 days after the 1st application (DAA1); T6 - two applications, one at R1 and the other at 21 DAA1; T7 - three applications: one at V5, the second 21 DAA1, and the third 21 DAA2; and T8 ­ control. The disease severity index, number of plants m-1, the mass of one thousand grains and grain yield were assessed. The observed means were submitted to the analysis of variance (ANOVA) and Duncan's test (p ≤ 0.05). The results showed significant differences in disease severity, weight of a thousand grains, and yield. The treatments with the lowest severity and highest grain yield were T5 and T6 with two applications at V5 and 21 DAA, and R1 and 21 DAA, respectively. ELATUS® is recommended to be applied twice, one at V5 and the second application 21 days after the first one, or one at R1 and the other 21 days after it, which presented good efficiency in fungus control and an increase in grain yield.

Para determinar el momento apropiado de la aplicación de fungicidas en el control de la oxidación asiática (Phakospsora pachyrhizi) de la soya, se evaluó la etapa de aplicación de fungicidas del grupo químico carboxamida + estrobirulina (ELATUS®), en condiciones de campo. El diseño experimental fue de bloques al azar con ocho tratamientos y cuatro repeticiones. Cada bloque estaba formado por cuatro filas de cinco metros de largo con una superficie total de 9 m². Los tratamientos fueron: T1 - una aplicación en la etapa V5; T2 - una aplicación en la etapa R1; T3 - una aplicación en la etapa R3; T4 - una aplicación en la etapa R5; T5 - dos aplicaciones, una en la fase V5 y otra 21 días después de la primera (DAA1); T6 - dos aplicaciones, una en la fase de R1 y otra 21 DAA1; T7 - tres aplicaciones; uno en el estadio V5, la segunda 21 DAA1, y la tercera 21 DAA2 y T8 ­ Testigo (control). A partir de los estudios realizados se evaluó el índice de gravedad de la enfermedad, el número de plantas m-1, peso de mil granos y el rendimiento de granos. Los resultados obtenidos han sido sometidos al análisis de varianza (ANOVA) y a la prueba de Duncan (p ≤ 0,05). Los resultados mostraron diferencias significativas en la gravedad de la enfermedad, peso de mil granos y en el rendimiento. Los tratamientos que presentaron menor gravedad y el más alto rendimiento de granos fueron T5 y T6 con dos aplicaciones a la etapa V5, 21 DAA, R1 y 21 DAA. Se recomienda la aplicación del fungicida ELATUS® dos veces, una en la fase V5 y 21 días después, o una en la etapa R1 y otra después de 21 días, procedimiento esos que mostraron una buena eficiencia en el control de hongos y aumento del rendimiento de granos.

Thiophene carboxamide inhibitors of JAK2 as potential treatments for myleoproliferative neoplasms.

A series of carboxamide-substituted thiophenes demonstrating inhibition of JAK2 is described. Development of this chemical series began with the bioisosteric replacement of a urea substituent by a pyridyl ring. Issues of chemical and metabolic stability were solved using the results of both in vitro and in vivo studies, ultimately delivering compounds such as 24 and 25 that performed well in an acute PK/PD model measuring p-STAT5 inhibition.

Solid-phase synthesis of a new diphosphate 5-aminoimidazole-4-carboxamide riboside (AICAR) derivative and studies toward cyclic AICAR diphosphate ribose.

The solid-phase synthesis of the first example of a new diphosphate AICAR derivative is reported. The new substance is characterized by the presence of a 5'-phosphate group while a second phosphate moiety is installed on a 5-hydroxypentyl chain attached to the 4-N-position of AICAR. Cyclization of the diphosphate derivative by pyrophosphate bond formation allowed for the formation of a novel AICAR-based cyclic ADP-ribose (cADPR) mimic.

Synthesis and evaluation of novel 1-(2-acylhydrazinocarbonyl)-cycloalkyl carboxamides as interleukin-1beta converting enzyme (ICE) inhibitors.

Novel 1-(2-acylhydrazinocarbonyl)cycloalkyl carboxamides were designed as peptidomimetic inhibitors of interleukin-1beta converting enzyme (ICE). A short synthesis was developed and moderately potent ICE inhibitors were identified (IC(50) values <100 nM). Most of the synthesized examples were selective for ICE versus the related cysteine proteases caspase-3 and caspase-8, although several dual-acting inhibitors of ICE and caspase-8 were identified. Several of the more potent ICE inhibitors were also shown to inhibit IL-1beta production in a whole cell assay (IC(50) < 500 nM).

Ring opening reactions: synthesis of AICAR analogs as potential antimetabolite agents.

In an attempt to improve the AzA selectivity of the 2-(aryl)alkylthio derivatives of adenosine, we planned the synthesis of the corresponding derivatives of the 5-N-ethylcarboxamidoadenosine (NECA). For this purpose, we designed the synthesis of 2-mercapto-NECA to be pursued by means of an opening-closure method We obtained the open AICAR analog; however, ring closure efforts failed to give the desired compound. The newly synthesized AICAR derivative could potentially be endowed with antiviral or antitumoral activity.

N-Arylpiperazine-1-carboxamide derivatives: a novel series of orally active nonsteroidal androgen receptor antagonists.

A novel series of N-arylpiperazine-1-carboxamide derivatives was synthesized and their androgen receptor (AR) antagonist activities and in vivo antiandrogenic properties were evaluated. Reporter assays indicated that trans-2,5-dimethylpiperazine derivatives are potent AR antagonists, and in this series trans-N-4-[4-cyano-3-(trifluoromethyl)phenyl]-N-(2,4-difluorophenyl)-2,5-dimethylpiperazine-1-carboxamide (18 g, YM-175735) exhibited the most potent antiandrogenic activity. Compared to bicalutamide, YM-175735 is an approximately 4-fold stronger AR antagonist and has slightly increased antiandrogenic activity, suggesting that YM-175735 may be useful in the treatment of prostate cancer.

Mechanism of action of Escherichia coli phosphoribosylaminoimidazolesuccinocarboxamide synthetase.

The conversion of ATP, L-aspartate, and 5-aminoimidazole-4-carboxyribonucleotide (CAIR) to 5-aminoimidazole-4-(N-succinylcarboxamide) ribonucleotide (SAICAR), ADP, and phosphate by phosphoribosylaminoimidazolesuccinocarboxamide synthetase (SAICAR synthetase) represents the eighth step of de novo purine nucleotide biosynthesis. SAICAR synthetase and other enzymes of purine biosynthesis are targets of natural products that impair cell growth. Prior to this study, no kinetic mechanism was known for any SAICAR synthetase. Here, a rapid equilibrium random ter-ter kinetic mechanism is established for the synthetase from Escherichia coli by initial velocity kinetics and patterns of linear inhibition by IMP, adenosine 5'-(beta,gamma-imido)triphosphate (AMP-PNP), and maleate. Substrates exhibit mutual binding antagonism, with the strongest antagonism between CAIR and either ATP or L-aspartate. CAIR binds to the free enzyme up to 200-fold more tightly than to the ternary enzyme-ATP-aspartate complex, but the latter complex may be the dominant form of SAICAR synthetase in vivo. IMP is a competitive inhibitor with respect to CAIR, suggesting the possibility of a hydrogen bond interaction between the 4-carboxyl and 5-amino groups of enzyme-bound CAIR. Of several aspartate analogues tested (hadacidin, l-malate, succinate, fumarate, and maleate), maleate was by far the best inhibitor, competitive with respect to L-aspartate. Inhibition by IMP and maleate is consistent with a chemical mechanism for SAICAR synthetase that parallels that of adenylosuccinate synthetase.

Demonstration of an alternative mechanism for G-to-G cross-link formation.

The cross-link dG-to-dG is an important product of DNA nitrosation. Its formation has commonly been attributed to nucleophilic substitution of N2 in a guaninediazonium ion by guanine, while recent studies suggest guanine addition to a cyanoamine derivative formed after dediazoniation, deprotonation, and pyrimidine ring-opening. The chemical viability of the latter mechanism is supported here by the experimental demonstration of rG-to-aG formation via rG addition to a synthetic cyanoamine derivative. Thus, all known products of nitrosative guanine deamination are consistent with the postulate of pyrimidine ring-opening. This postulated mechanism not only explains what is already known but also suggests that other products and other cross-links also might be formed in DNA deamination. The study suggests one possible new product: the structure isomer aG(N1)-to-rG(C2) of the classical G(N2)-to-G(C2) cross-link. While the formation of aG(N2)-to-rG(C2) has been established by chemical synthesis, the structure isomer aG(N1)-to-rG(C2) has been assigned tentatively based on its MS/MS spectrum and because this assignment is reasonable from a mechanistic perspective. Density functional calculations show preferences for the amide-iminol tautomer of the classical cross-link G(N2)-to-G(C2) and the amide-amide tautomer of G(N1)-to-G(C2). Moreover, the results suggest that both cross-links are of comparable thermodynamic stability, and that there are no a priori energetic or structural reasons that would prevent the formation of the structure isomer in the model reaction or in DNA.

Small molecule inhibition of hepatitis C virus E2 binding to CD81.

The hepatitis C virus (HCV) is a causal agent of chronic liver infection, cirrhosis, and hepatocellular carcinoma infecting more than 170 million people. CD81 is a receptor for HCV envelope glycoprotein E2. Although the binding of HCV-E2 with CD81 is well documented the role of this interaction in the viral life cycle remains unclear. Host specificity and mutagenesis studies suggest that the helix D region of CD81 mediates binding to HCV-E2. Structural analysis of CD81 has enabled the synthesis of small molecules designed to mimic the space and hydrophobic features of the solvent-exposed face on helix D. Utilizing a novel bis-imidazole scaffold a series of over 100 compounds has been synthesized. Seven related, imidazole-based compounds were identified that inhibit binding of HCV-E2 to CD81. The inhibitory compounds have no short-term effect on cellular expression of CD81 or other tetraspanins, do not disrupt CD81 associations with other cell surface proteins, and bind reversibly to HCV-E2. These results provide an important proof of concept that CD81-based mimics can disrupt binding of HCV-E2 to CD81.

Human AICAR transformylase: role of the 4-carboxamide of AICAR in binding and catalysis.

We have prepared 4-substituted analogues of 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) to investigate the specificity and mechanism of AICAR transformylase (AICAR Tfase). Of the nine analogues of AICAR studied, only one analogue, 5-aminoimidazole-4-thiocarboxamide ribonucleotide, was a substrate, and it was converted to 6-mercaptopurine ribonucleotide. The other analogues either did not bind or were competitive inhibitors, the most potent being 5-amino-4-nitroimidazole ribonucleotide with a K(i) of 0.7 +/- 0.5 microM. The results show that the 4-carboxamide of AICAR is essential for catalysis, and it is proposed to assist in mediating proton transfer, catalyzing the reaction by trapping of the addition compound. AICAR analogues where the nitrogen of the 4-carboxamide was derivatized with a methyl or an allylic group did not bind AICAR Tfase, as determined by pre-steady-state burst kinetics; however, these compounds were potent inhibitors of IMP cyclohydrolase (IMP CHase), a second activity of the bifunctional mammalian enzyme (K(i) = 0.05 +/- 0.02 microM for 4-N-allyl-AlCAR). It is proposed that the conformation of the carboxamide moiety required for binding to AICAR Tfase is different than the conformation required for binding to IMP CHase, which is supported by inhibition studies of purine ribonucleotides. It is shown that 5-formyl-AICAR (FAICAR) is a product inhibitor of AICAR Tfase with K(i) of 0.4 +/- 0.1 microM. We have determined the equilibrium constant of the transformylase reaction to be 0.024 +/- 0.001, showing that the reaction strongly favors AICAR and the 10-formyl-folate cofactor. The coupling of the AICAR Tfase and IMP CHase activities on a single polypeptide allows the overall conversion of AICAR to IMP to be favorable by coupling the unfavorable formation of FAICAR with the highly favorable cyclization reaction. The current kinetic studies have also indicated that the release of FAICAR is the rate-limiting step, under steady-state conditions, in the bifunctional enzyme and channeling is not observed between AICAR Tfase and IMP CHase.

Radiochemical assay of adenylosuccinase: demonstration of parallel loss of activity toward both adenylosuccinate and succinylaminoimidazole carboxamide ribotide in liver of patients with the enzyme defect.

A radiochemical assay for adenylosuccinase, an enzyme which intervenes twice in the biosynthesis of adenine nucleotides, has been developed. The two substrates of the enzyme, succinylaminoimidazole carboxamide ribotide (SAICAR) and adenylosuccinate (S-AMP), were synthesized in radioactive form by incubating [2,3-14C]fumarate and, respectively, AICAR and AMP with partially purified adenylosuccinase from yeast. Enzyme activities were determined by measuring the release of labeled fumarate after its separation from the substrate by chromatography on polyethyleneimine thin-layer plates. The ratio of the activity of adenylosuccinase measured with SAICAR compared to that with S-AMP was about 1 in crude extracts of rat liver and muscle and around 0.5 in human liver. In rat and human liver, but not in rat muscle, 20 to 40% of both activities of adenylosuccinase were lost after freezing at -80 degrees C followed by thawing. In the liver of patients with adenylosuccinase deficiency, in whom the deficiency had hitherto been measured only with S-AMP, the activity of the enzyme toward S-AMP and SAICAR was found to be lost in parallel. This is in accordance with the finding that both SAICA-riboside and succinyladenosine accumulate in adenylosuccinase-deficient patients.

5-Amino-4-(diazoacetyl)-1-beta-D-ribofuranosylimidazole, a new antileukemic agent.

5-Amino-4-(diazoacetyl)-1-beta-D-ribofuranosylimidazole (15), 5-amino-4-(chloroacetyl)-1-beta-D-ribofuranosylimidazole (16), and a number of related imidazole ribonucleosides have been synthesized. Compounds 15 and 16 are cytotoxic to both H.Ep.-2 and L1210 leukemia cells in culture. The (diazoacetyl)imidazole 15 is also active against the P388 leukemia in mice.

Synthesis and biological activity of 5-thiobredinin and certain related 5-substituted imidazole-4-carboxamide ribonucleosides.

A number of 5-substituted imidazole-4-carboxamide ribonucleosides were prepared and tested for their biological activity. Treatment of 5-chloro-1-beta-D-ribofuranosylimidazole-4-carboxamide (2) with methanethiol provided 5-(methylthio)-1-beta-D-ribofuranosylimidazole-4-carboxamide (3a). Similar treatment of 2 with ethanethiol or benzenemethanethiol gave the corresponding 5-ethylthio and 5-benzylthio derivatives 3b and 3c. Oxidation of 3a and 3b with m-chloroperoxybenzoic acid furnished the corresponding sulfonyl derivatives 4a and 4b. Reductive cleavage of 3c with sodium naphthalene or Na/NH3 gave 5-mercapto-1-beta-D-ribofuranosylimidazole-4-carboxamide (5-thiobredinin, 5). Direct treatment of 2 with sodium hydrosulfide provided an alternate route to 5, the structure of which was established by single-crystal X-ray analysis. 5-Thiobredinin has a zwitterionic structure similar to that of bredinin. Glycosylation of persilylated ethyl 5(4)-methylimidazole-4(5)-carboxylate (6) with 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose in the presence of SnCl4 provided a quantitative yield of the corresponding tri-O-benzoyl nucleoside 7. Debenzoylation of 7 with MeOH/NH3 at ambient temperature gave ethyl 5-methyl-1-beta-D-ribofuranosylimidazole-4-carboxylate (8). Further ammonolysis of 8 or 7 at elevated temperature and pressure gave 5-methyl-1-beta-D-ribofuranosylimidazole-4-carboxamide (9). All of these ribonucleosides were tested in Vero cell cultures and in mice against certain viruses. Compounds 3a and 3c exhibited significant activity against vaccinia virus in vitro, whereas 4a was effective against Rift Valley fever virus in mice. 5-Thiobredinin failed to exhibit appreciable antiviral or cytostatic activity (against L1210 and P388) in cell culture.