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Introduction: The identification of chemical compounds that interfere with SARS-CoV-2 replication continues to be a priority in several academic and pharmaceutical laboratories. Computational tools and approaches have the power to integrate, process and analyze multiple data in a short time. However, these initiatives may yield unrealistic results if the applied models are not inferred from reliable data and the resulting predictions are not confirmed by experimental evidence. Methods: We undertook a drug discovery campaign against the essential major protease (MPro) from SARS-CoV-2, which relied on an in silico search strategy -performed in a large and diverse chemolibrary- complemented by experimental validation. The computational method comprises a recently reported ligand-based approach developed upon refinement/learning cycles, and structure-based approximations. Search models were applied to both retrospective (in silico) and prospective (experimentally confirmed) screening. Results: The first generation of ligand-based models were fed by data, which to a great extent, had not been published in peer-reviewed articles. The first screening campaign performed with 188 compounds (46 in silico hits and 100 analogues, and 40 unrelated compounds: flavonols and pyrazoles) yielded three hits against MPro (IC50 ≤ 25 µM): two analogues of in silico hits (one glycoside and one benzo-thiazol) and one flavonol. A second generation of ligand-based models was developed based on this negative information and newly published peer-reviewed data for MPro inhibitors. This led to 43 new hit candidates belonging to different chemical families. From 45 compounds (28 in silico hits and 17 related analogues) tested in the second screening campaign, eight inhibited MPro with IC50 = 0.12-20 µM and five of them also impaired the proliferation of SARS-CoV-2 in Vero cells (EC50 7-45 µM). Discussion: Our study provides an example of a virtuous loop between computational and experimental approaches applied to target-focused drug discovery against a major and global pathogen, reaffirming the well-known "garbage in, garbage out" machine learning principle.
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We report the design, the synthesis and the biological evaluation of the analgesic and anti-inflammatory activities of furoxanyl N-acylhydrazones (furoxanyl-NAH) by applying molecular hybridization approach. Hybrid compounds with IL-8-release inhibition capabilities were identified. Among them, furoxanyl-NAH, 17, and benzofuroxanyl-derivative, 24, together with furoxanyl-NAH derivative, 31, without IL-8 inhibition displayed both orally analgesic and anti-inflammatory activities. These hybrid derivatives do not have additional LOX- or COX-inhibition activities. For instance, LOX-inhibition by furoxanyl-NAH derivative, 42, emerged as a structural lead to develop new inhibitors. The lack of mutagenicity of the active derivatives 17, 31, and 42, allow us to propose them as candidates for further clinical studies. These results confirmed the success in the exploitation of hybridization strategy for identification of novel N-acylhydrazones (NAH) with optimized activities.
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Analgésicos/química , Analgésicos/farmacología , Antiinflamatorios/química , Antiinflamatorios/farmacología , Hidrazonas/química , Hidrazonas/farmacología , Analgésicos/síntesis química , Analgésicos/uso terapéutico , Animales , Antiinflamatorios/síntesis química , Antiinflamatorios/uso terapéutico , Línea Celular , Inhibidores de la Ciclooxigenasa/síntesis química , Inhibidores de la Ciclooxigenasa/química , Inhibidores de la Ciclooxigenasa/farmacología , Inhibidores de la Ciclooxigenasa/uso terapéutico , Diseño de Fármacos , Femenino , Humanos , Hidrazonas/síntesis química , Hidrazonas/uso terapéutico , Inflamación/tratamiento farmacológico , Interleucina-8/inmunología , Inhibidores de la Lipooxigenasa/síntesis química , Inhibidores de la Lipooxigenasa/química , Inhibidores de la Lipooxigenasa/farmacología , Inhibidores de la Lipooxigenasa/uso terapéutico , Masculino , Ratones , Oxadiazoles/síntesis química , Oxadiazoles/química , Oxadiazoles/farmacología , Oxadiazoles/uso terapéutico , Dolor/tratamiento farmacológico , RatasRESUMEN
Cancer preventive agents (CPA) are drugs able to suppress the carcinogen metabolic activation or block the formation of ultimate carcinogens. CPA could act through various molecular mechanisms, for example by interfering with the action of procarcinogen. This could be attained by increasing the phase II enzymes levels of quinone reductase (QR) and glutathione S-transferase (GST). New flavonoids, especially chalcones, have been identified as in vivo monofunctional phase II enzymes inducers. Oral administration of chalcone, 4, and both p-methoxy-substituted chalcones, 6 and 14, increased hepatic QR activity with concomitant decrease in CYP1A1 activity, a member of the most important group of phase I enzymes cytochrome P450. Among them, 4 also increased GST activity. While p-bromo-substituted chalcone 8 was the best inducer of QR it decreased hepatic GST expression and cytochrome P450, being the most effective decreasing cytochrome P450-expression. Thienyl-chalcone 20 being the bioisostere of chalcone 4 did not display the same in vivo profile in the phase I level modification. As chalcone 4 its bioisostere, chalcone 20, displayed low DNA strand breakage and absence of mutagenicity. Also, in our preliminary in vivo tumourigenesis/chemopreventive and acute-toxicity studies, chalcones 4, 6 and 8 showed the best behaviours as CPA justifying additional studies that are ongoing.
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Anticarcinógenos/química , Anticarcinógenos/uso terapéutico , Chalconas/química , Chalconas/uso terapéutico , Neoplasias Hepáticas/prevención & control , Hígado/efectos de los fármacos , Animales , Anticarcinógenos/farmacología , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Chalconas/farmacología , Ensayo Cometa , Citocromo P-450 CYP1A1/metabolismo , Femenino , Humanos , Hígado/enzimología , Hígado/patología , Neoplasias Hepáticas/enzimología , Modelos Moleculares , NAD(P)H Deshidrogenasa (Quinona)/metabolismo , Ratas , Ratas Sprague-Dawley , Ratas WistarRESUMEN
Phenazine 5,10-dioxides are prodrugs for antitumor therapy that undergo hypoxic-selective bioreduction to form cytotoxic species. Here we investigate the expanded system benzo[a]phenazine 7,12-dioxides as selective hypoxic cytotoxin-scaffold. The clonogenic survival of V79 cells on aerobic and anaerobic conditions, conduct us to study antiproliferative activity on Caco-2 tumoral cells in normoxia. Electrochemical, DNA-interaction and DNA-damage studies were performed to establish the mode of action. The results demonstrated the potential biological properties of the studied scaffold being derivatives 6-10 structural hits for further chemical-modifications to become into therapeutics for solid tumors. Compounds 6 and 8 with cytotoxicity against V79 cells in both conditions (aerobia and anaerobia) were also cytotoxic against Caco-2 tumoral cells in aerobiosis.
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Antineoplásicos/química , Fenazinas/química , Animales , Antineoplásicos/síntesis química , Antineoplásicos/uso terapéutico , Células CACO-2 , Hipoxia de la Célula/efectos de los fármacos , Línea Celular , Neoplasias del Colon/tratamiento farmacológico , Cricetinae , Daño del ADN , Fragmentación del ADN , Humanos , Fenazinas/síntesis química , Fenazinas/toxicidadRESUMEN
Four new palladium(II) complexes with the formula Pd(L)(2), where L are quinoxaline-2-carbonitrile N(1),N(4)-dioxide derivatives, were synthesized as a contribution to the chemistry and pharmacology of metal compounds with this class of pharmacologically interesting bioreductive prodrugs. Compounds were characterized by elemental, conductometric and thermogravimetric analyses, fast atom bombardment mass spectrometry (FAB-MS) and electronic, Fourier transform infrared (FTIR) and (1)H-nuclear magnetic resonance spectroscopies. The complexes were subjected to cytotoxic evaluation on V79 cells in hypoxic and aerobic conditions. In addition, a preliminary study on interaction with plasmid DNA in normoxia was performed. Complexes showed different in vitro biological behavior depending on the nature of the substituent on the quinoxaline ring. Pd(L1)(2) and Pd(L2)(2), where L1 is 3-aminoquinoxaline-2-carbonitrile N(1),N(4)-dioxide and L2 is 3-amino-6(7)-methylquinoxaline-2-carbonitrile N(1),N(4)-dioxide, showed non selective cytotoxicity, being cytotoxic either in hypoxic or in aerobic conditions. On the other hand, Pd(L3)(2), where L3 is 3-amino-6(7)-chloroquinoxaline-2-carbonitrile N(1),N(4)-dioxide, resulted in vitro more potent cytotoxin in hypoxia (P=5.0 microM) than the corresponding free ligand (P=9.0 microM) and tirapazamine (P=30.0 microM), the first bioreductive cytotoxic drug introduced into clinical trials. In addition, it showed a very good selective cytotoxicity in hypoxic conditions, being non-cytotoxic in normoxia. Its hypoxic cytotoxicity relationship value, HCR, was of the same order than those of other hypoxia selective cytotoxins (i.e., Mitomycine C, Misonidazole and the N-oxide RB90740). Interaction of the complexes with plasmid DNA in normoxia showed dose dependent ability to relax the negative supercoiled forms via different mechanisms. Pd(L2)(2) introduced a scission event in supercoiled DNA yielding the circular relaxed form. Meanwhile, both Pd(L1)(2) and Pd(L3)(2) produced the loss of negative supercoils rendering a family of topoisomers with reduced electrophoretic mobility. Pd(L3)(2) showed a more marked effect than Pd(L1)(2). Indeed, for the highest doses assayed, Pd(L3)(2) was even able to introduce positive supercoils on the plasmid DNA.
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Nitrilos/química , Nitrilos/farmacología , Compuestos Organometálicos/química , Paladio/química , Profármacos/química , Quinoxalinas/química , Quinoxalinas/farmacología , Animales , Antineoplásicos/síntesis química , Antineoplásicos/química , Antineoplásicos/farmacología , Línea Celular , Cricetinae , Cricetulus , ADN/química , ADN/genética , Ligandos , Espectroscopía de Resonancia Magnética , Compuestos Organometálicos/síntesis química , Compuestos Organometálicos/farmacología , Paladio/farmacología , Plásmidos/química , Plásmidos/genética , Profármacos/síntesis química , Profármacos/farmacología , Espectrometría de Masa Bombardeada por Átomos Veloces , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
New 5-nitroindazole derivatives were developed and their antichagasic properties studied. Eight compounds (14-18, 20, 26 and 28) displayed remarkable in vitro activities against Trypanosoma cruzi (T. cruzi). Its unspecific cytotoxicity against macrophages was evaluated being not toxic at a concentration at least twice that of T. cruzi IC(50), for some derivatives. The electrochemical studies, parasite respiration studies and ESR experiment showed that 5-nitroindazole derivatives not be able to yield a redox cycling with molecular oxygen such as occurs with nifurtimox (Nfx). The study on the mechanism of action proves to be related to the production of reduced species of the nitro moiety similar to that observed with benznidazole.
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Enfermedad de Chagas/tratamiento farmacológico , ADN Protozoario/efectos de los fármacos , Indazoles/farmacología , Nitroimidazoles/farmacología , Pruebas de Sensibilidad Parasitaria , Tripanocidas/envenenamiento , Trypanosoma cruzi/efectos de los fármacos , Enfermedad de Chagas/genética , Cristalografía por Rayos X , Células HeLa , Humanos , Indazoles/química , Indazoles/uso terapéutico , Nitroimidazoles/síntesis química , Oxidación-Reducción/efectos de los fármacos , Relación Estructura-Actividad , Tripanocidas/farmacocinéticaRESUMEN
We determined the chemosensitizer effect of phenazine dioxide derivatives to cisplatin and the possible mechanism of action on bladder cancer cells. Anti-proliferative activity of nine phenazine dioxide derivatives in presence or absence of cisplatin was evaluated in two bladder tumor human cells T24 and 253 J and one non tumor cell line V79-4. The sensitizer effect of the combined treatment was determined by chromosomal aberrations and micronucleus test. A possible mechanism of action of the sensitizer compounds as HDACi was also investigated.The phenazine dioxide 2c combined with cisplatin induced a cell cycle arrest on bladder cancer cells and resensitize the invasive and cisplatin resistant 253 J cell line. The HDAC inhibitory activity appears as one of the mechanism of action of the compound. The low toxicity levels against normal cells point out the phenazine dioxide derivative 2c as a very good scaffold for further design of HDACi sensitizer agents.
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Antineoplásicos/farmacología , Cisplatino/farmacología , Inhibidores de Histona Desacetilasas/farmacología , Fenazinas/farmacología , Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Daño del ADN , Sinergismo Farmacológico , Humanos , Neoplasias de la Vejiga Urinaria/tratamiento farmacológicoRESUMEN
Some derivatives of phenazine 5,10-dioxide are selectively toxic to hypoxic cells commonly found in solid tumors. Previous studies of the phenazine 5,10-dioxide mechanism of action indicated that a bioreduction process could be involved in its selective toxicities, maybe as result of its potential H(*)-releasing capability in hypoxia. The major unresolved aspect of the mechanism of phenazine 5,10-dioxides is the identity of the reductase(s) in the cell responsible for activating the drug to its toxic form and metabolites. We have studied the metabolism in both hypoxia and oxia of some selected 2-amino and 2-hydroxyphenazine 5,10-dioxides, 1- 5, using rat liver microsomal and cytosol fractions. Differential hypoxic/oxic metabolism was found to be correlated to a compound's cytotoxic selectivity but, in general, without metabolic differences between liver microsomal or cytosolic enzymes. Dicoumarol and ketoconazole were found to inhibit the hypoxic metabolism of the most selective phenazine 5,10-dioxide, 1, inferring a role for DT-diaphorase and cytochrome P450. The least hypoxic selective agents, 4 and 5, possess different hypoxia-metabolic profiles as compared to derivative 1, explaining the differential cytotoxic biological behavior. The nonselective derivative, 2, suffered bioreduction in both conditions and, according to the inhibition studies with dicoumarol and ketoconazole, involves both DT-diaphorase and cytochrome P450. The nontoxic derivative, 3, showed poor bioreductive behavior.
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Sistema Enzimático del Citocromo P-450/metabolismo , Hipoxia/metabolismo , NAD(P)H Deshidrogenasa (Quinona)/metabolismo , Fenazinas/metabolismo , Fenazinas/toxicidad , Aldehído Oxidasa/metabolismo , Animales , Cromatografía Líquida de Alta Presión , Cromatografía en Capa Delgada , Sistema Enzimático del Citocromo P-450/química , Citosol/efectos de los fármacos , Citosol/metabolismo , Dicumarol/farmacología , Cetoconazol/farmacología , Masculino , Microsomas Hepáticos/efectos de los fármacos , Microsomas Hepáticos/metabolismo , Estructura Molecular , NAD(P)H Deshidrogenasa (Quinona)/química , Oxidación-Reducción , Fenazinas/química , Ratas , Ratas Sprague-Dawley , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
We studied the in vitro antitumoral effect of a series of phenazine di- N-oxide derivatives, named 2-chloroacetylamino-7(8)-nitrophenazine N(5), N(10)-dioxide (1), 2-amino-7(8)-(1,3-dioxol-2-yl)phenazine N(5), N(10)-dioxide (2), 2-chloroacetylamino-7(8)-(1,3-dioxol-2-yl)phenazine N(5), N(10)-dioxide (3), and 2-amino-7(8)-methoxyphenazine N(5), N(10)-dioxide (4), on Caco-2 cells. These phenazine N(5), N(10)-dioxide derivatives belong to our in-house chemical library. The products were selected according to their stereoelectronic characteristics and taking into account their differential cytotoxicity against V79 cells. Human colorectal adenocarcinoma cell line Caco-2 was used to study the cell growth inhibition capacity of these compounds, their capacity of altering the cell cycle and possible induction of apoptosis, DNA fragmentation, and genotoxic damage. The IC 50 after 24 h of incubation was lower for 1, 2, and 3 (4.8, 46.8, and 8.2 microM, respectively) than for 4 (474.7 microM). Compound 1 induced arrest in the G2/M phase at 24 and 48 h of treatment and apoptosis at the highest doses at 24 h of treatment. These facts were corroborated with caspase 3, caspase 9, and cytochrome c activation and DNA fragmentation at 24 h of treatment. The derivatives studied induced neither significant single strand breaks nor oxidative damage at the different studied times. We concluded that among the series of N(5), N(10)-dioxide phenazine derivatives analyzed, 1, which contains a nitro moiety and a chloroacetamide group, is the most promising as an antitumoral compound.
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Antineoplásicos/farmacología , Células CACO-2/efectos de los fármacos , Fenazinas/farmacología , Células CACO-2/metabolismo , Células CACO-2/patología , Caspasas/biosíntesis , Ciclo Celular/efectos de los fármacos , Ensayo Cometa , Citocromos c/biosíntesis , Daño del ADN , Ensayos de Selección de Medicamentos Antitumorales , Formazáns/metabolismo , Humanos , Estructura Molecular , Fenazinas/química , Relación Estructura-Actividad , Sales de Tetrazolio/metabolismoRESUMEN
Taking into account our previous studies on cytotoxic metal compounds, new copper complexes with 3-aminoquinoxaline-2-carbonitrile N1,N4-dioxide derivatives as ligands were synthesized and characterized by different spectroscopic methods. The hypoxic selective cytotoxicity towards V79 cells and the superoxide dismutase-like activity of the complexes were determined and related to physicochemical properties of the compounds. In particular, the copper(II) complex with 3-amino-6-chloro-7-fluoroquinoxaline-2-carbonitrile N1,N4-dioxide showed cytotoxic selectivity in hypoxia being the most lipophilic compound of the series. On the contrary, the complex with 3-aminoquinoxaline-2-carbonitrile N1,N4-dioxide was cytotoxic but not selective and that with 3-amino-7-chloro-6-methoxy-quinoxaline-2-carbonitrile N1,N4-dioxide was not cytotoxic towards V79 cells neither in oxia nor in hypoxia in the assayed conditions. The sigmam Hammett substituent electronic descriptor was related to the effect in hypoxic conditions and the SOD-like activity was correlated to the effect in normoxia.
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Antineoplásicos/síntesis química , Antineoplásicos/farmacología , Cobre , Compuestos Organometálicos/síntesis química , Compuestos Organometálicos/farmacología , Quinoxalinas/síntesis química , Quinoxalinas/farmacología , Animales , Células Cultivadas , Cobre/farmacología , Cricetinae , Cricetulus , Electroquímica , Espectroscopía de Resonancia por Spin del Electrón , Hipoxia/fisiopatología , Espectrometría de Masa Bombardeada por Átomos Veloces , Espectrofotometría Infrarroja , Superóxido Dismutasa/metabolismoRESUMEN
Two different families of N-oxide containing heterocycles were evaluated as in vitro growth inhibitors of T. cruzi. Both families of heterocycles were selected from our in-house library of compounds as analogues of active anti-T. cruzi N-oxide containing heterocycles. Derivatives from pyrimido[1,2-a]quinoxaline 6-oxide family were poorly active at the assayed doses. However, phenazine 5,10-dioxide derivatives displayed good to excellent anti-T. cruzi activities. The anti-T. cruzi activity of phenazine derivatives was related to substituent' electronic descriptors, sigma(p)(-). Derivatives 19, 20 and 23 were the most cytotoxic compounds against the protozoan and became excellent hit for further structural modifications.
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Antimaláricos/síntesis química , Antimaláricos/farmacología , Óxidos N-Cíclicos/síntesis química , Óxidos N-Cíclicos/farmacología , Fenazinas/síntesis química , Fenazinas/farmacología , Quinoxalinas/síntesis química , Quinoxalinas/farmacología , Trypanosoma cruzi/efectos de los fármacos , Animales , Antimaláricos/química , Óxidos N-Cíclicos/química , Electrones , Concentración 50 Inhibidora , Estructura Molecular , Fenazinas/química , Quinoxalinas/química , Relación Estructura-Actividad , Trypanosoma cruzi/citologíaRESUMEN
As a contribution to the development of novel vanadyl complexes with potential insulin-mimetic activity, three new oxovanadium(IV) complexes with the formula VO(L)(2), where L are 3-amino-quinoxaline-2-carbonitrile N(1),N(4)-dioxide derivatives, have been synthesized. Complexes have been characterized by elemental and thermal analyses, fast atom bombardment mass spectroscopy (FAB-MS), conductivity measurements and electronic, Fourier transform infrared (FTIR) and electron paramagnetic resonance (EPR) spectroscopies. The in vitro insulin-mimetic activity of the vanadyl complexes has been estimated by lipolysis inhibition tests, in which the inhibition of the release of free fatty acid from isolated rat adipocytes treated with epinephrine was determined. All the complexes showed inhibitory effects on free fatty acid release. [V(IV)O(3-amino-6(7)-bromoquinoxaline-2-carbonitrile N(1),N(4)-dioxide)(2)] exhibited higher in vitro insulin-mimetic activity than the very active bis(6-methylpicolinato)oxovanadium(IV), VO(6mpa)(2). This new vanadyl complex is expected to exhibit a higher blood glucose lowering activity than VO(6mpa)(2) in diabetic animals.
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Hipoglucemiantes/farmacología , Imitación Molecular , Compuestos Organometálicos/síntesis química , Compuestos Organometálicos/farmacología , Quinoxalinas/farmacología , Vanadatos/farmacología , Adipocitos/efectos de los fármacos , Adipocitos/metabolismo , Animales , Células Cultivadas , Espectroscopía de Resonancia por Spin del Electrón , Efedrina/farmacología , Hipoglucemiantes/síntesis química , Insulina/farmacología , Lipólisis/efectos de los fármacos , Masculino , Estructura Molecular , Compuestos Organometálicos/química , Quinoxalinas/química , Ratas , Ratas Wistar , Vanadatos/químicaRESUMEN
Increased attention has centered on exploiting hypoxia in tumors for targeting the design of selective antitumor agents. This review presents an update of the principal families of compounds under study and in clinical trials, such as N-oxide derivatives, nitro compounds and quinone derivatives. Especially promising for bioreductive activation is the reduction of some moieties able to trigger a mechanism that releases cytotoxic antitumor drugs. The most remarkable redox-activated triggers are presented, N-oxide, nitro, azido, quinone, metal ions, 1,2-benzisoxazolyl and sulfoxide moieties.
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Antineoplásicos/uso terapéutico , Citotoxinas/uso terapéutico , Hipoxia/tratamiento farmacológico , Neoplasias/tratamiento farmacológico , Animales , Humanos , Oxidación-ReducciónRESUMEN
As an effort to develop novel selective hypoxia-cytotoxins and to improve bioavailability and pharmacological and toxicological properties of quinoxaline N1,N4-dioxide derivatives (L1 = 3-amino-6(7)-chloroquinoxaline-2-carbonitrile N1,N4-dioxide, L2 = 3-amino-6(7)-bromoquinoxaline-2-carbonitrile N1,N4-dioxide and L3 = 3-amino-6(7)-methylquinoxaline-2-carbonitrile N1,N4-dioxide) and to get a synergism among metals and these type of bioreductive agents, L2 and three novel Cu(II) complexes of general formulae [Cu(II)(H2O)x(L - H)2], where L = L1 (x = 1), L2 (x = 0) or L3 (x = 2) were developed. L2 and complexes were synthesized and structurally characterized by elemental and thermal analyses, and FTIR, electronic, MS, NMR, and EPR spectroscopies. The new compounds were subjected to cytotoxic evaluation in V79 cells in hypoxic and aerobic conditions. The complexes showed excellent selective cytotoxicity in hypoxia, being their cytotoxicity similar to or higher than that of the ligands L1-L3. Besides, the copper complexes were so poorly cytotoxic in oxia as the free ligands. In addition, for the first time Cu(II)-quinoxaline complexes are reported as a family of hypoxic cytotoxins.
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Antineoplásicos/síntesis química , Cobre/farmacología , Quinoxalinas/química , Animales , Antineoplásicos/química , Antineoplásicos/farmacología , Hipoxia de la Célula , Cobre/química , Cricetinae , Cricetulus , Relación Dosis-Respuesta a Droga , Espectroscopía de Resonancia por Spin del Electrón , Fibroblastos , Modelos Moleculares , Compuestos Organometálicos/síntesis química , Compuestos Organometálicos/química , Compuestos Organometálicos/farmacología , Quinoxalinas/farmacología , Espectrometría de Masa Bombardeada por Átomos Veloces , Espectrofotometría Infrarroja , Propiedades de SuperficieRESUMEN
The aim of this study was to investigate the capability of phenazine dioxides, recognized bioreductive antitumour agents, as carriers for (99m)Tc in order to generate potential theranostic radiopharmaceuticals towards hypoxic solid tumours. Two different phenazine dioxides were used as ligands for the (99m)Tc-tricarbonyl core in order to prepare the potential radiopharmaceuticals. The main physicochemical and biological properties were evaluated. Biodistribution of the two radiotracers was studied at different time points after intravenous injection in tumour bearing animals. Both compounds were obtained in high yield and radiochemichal purity. They were stable in labelling milieu, in human plasma and in the presence of histidine. Biodistribution studies in mice were characterized by slow blood clearance and persistent liver uptake, results that correlate with the values of lipophilicities and protein binding. Both the complexes showed good tumour uptake, which remained constant during the studied period. Tumour/muscle ratios proved very favourable, comparable to those of FMISO in the same animal model. On the other hand, tumour/blood ratios were low due to high blood uptake. The use of phenazine dioxides as ligands for the preparation of potential (99m)Tc-radiopharmaceuticals towards solid tumours is possible since tumour uptake and retention are promising although high blood and liver uptake are drawbacks worth consideration.
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Hipoxia/diagnóstico por imagen , Neoplasias Pulmonares/diagnóstico por imagen , Fenazinas/farmacocinética , Radiofármacos/farmacocinética , Tecnecio/farmacocinética , Animales , Hipoxia de la Célula , Modelos Animales de Enfermedad , Ratones , Cintigrafía , Distribución TisularRESUMEN
Metabolism of three different agro-pesticides widely used in Uruguay, the insecticides imidacloprid and thiamethoxam and the antiparasite nitroxinil, by bovine ruminal fluid, as supply of anaerobic microorganims, was studied. Complete ruminal fluid was incubated with each of the agrochemicals in different conditions, varying time, nutrients, and nitroethane supplementation as methanogenesis modificator. Only biotransformation was detected for nitroxinil in some of the studied variables. In the optimized condition only one product was generated and the chemical structure of this main metabolite was elucidated using combined spectroscopies evidencing a structural motive unrelated with the products of the corresponding mammal biotransformation results of reduction, and substitution processes. The ruminal generation of the metabolite was confirmed. In order to employ this anaerobic microbial system as potential bioremediator of agrochemical-contaminated soils, the toxicity, against mammal cells, and the mutagenicity, using Ames test, of the product of biotransformation were studied. The lack of toxic effects encouraged us to propose the ruminal system as a plausible system for agrochemicals bioremediation.
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Imidazoles/metabolismo , Nitrocompuestos/metabolismo , Nitroxinilo/metabolismo , Oxazinas/metabolismo , Plaguicidas/metabolismo , Tiazoles/metabolismo , Animales , Biodegradación Ambiental , Líquidos Corporales/metabolismo , Líquidos Corporales/microbiología , Bovinos , Masculino , Neonicotinoides , Nitroxinilo/toxicidad , Plaguicidas/toxicidad , Rumen/metabolismo , Rumen/microbiología , Tiametoxam , Factores de Tiempo , UruguayRESUMEN
As a contribution to the identification of the relevant species for biological activity and the understanding of structure-activity relationships of [V(IV)O(L-2H)(NN)] antitrypanosomal complexes (NN is a bidentate polypyridyl DNA intercalator; L is a tridentate salicylaldehyde semicarbazone derivative), new [V(V)O2(L-2H)] complexes and [V(IV)O(L-2H)(NN)] complexes including bipy or dppz (dipyrido[3,2-a: 2',3'-c]phenazine) co-ligands are prepared and characterized in the solid state and in solution. Their activity is evaluated on Trypanosoma cruzi. The lipophilicity, as structural descriptor related to bioactivity, of the whole [V(IV)O(L-2H)(NN)] series is determined. Furthermore, the antiproliferative effect of those new compounds showing activity against T. cruzi is evaluated on the genetically related parasite T. brucei with the aim to develop broad spectrum agents. The new [V(IV)O(L-2H)(dppz)] complexes are about ten to fifteen times more toxic to T. cruzi than the bipy analogues and show quite good in vitro activity on T. brucei brucei. They are shown to interact with DNA, suggesting that this biomolecule may be the parasite target. The stability of the V(IV)O-complexes in solution is accessed by several techniques. Globally the data suggest that the relevant species for biological activity are the [V(IV)O(L-2H)(NN)] compounds, their order of activity being dependent on the NN nature, but not much on the substitution on the salicylaldehyde semicarbazone moiety. A parabolic relationship between biological response and lipophilicity (determined as RM=log [(1/Rf)-1] by a TLC method) is obtained. From this correlation an optimum RM value, close to 1.44, was found, which may be used as design guide for future development of antitrypanosomal compounds.
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Complejos de Coordinación/química , Tripanocidas/química , Vanadio , Animales , Complejos de Coordinación/síntesis química , Complejos de Coordinación/farmacología , Cristalografía por Rayos X , Estabilidad de Medicamentos , Espectroscopía de Resonancia Magnética , Microscopía de Fuerza Atómica , Modelos Moleculares , Estructura Molecular , Relación Estructura-Actividad , Tripanocidas/síntesis química , Tripanocidas/farmacología , Trypanosoma cruzi/efectos de los fármacos , Vanadio/química , Vanadio/farmacologíaRESUMEN
Hypoxic regions of tumours are associated with increased resistance to radiation and chemotherapy. Nevertheless, hypoxia has been used as a tool for specific activation of some antitumour prodrugs, named bioreductive agents. Phenazine dioxides are an example of such bioreductive prodrugs. Our 2D-quantitative structure activity relationship studies established that phenazine dioxides electronic and lipophilic descriptors are related to survival fraction in oxia or in hypoxia. Additionally, statistically significant models, derived by partial least squares, were obtained between survival fraction in oxia and comparative molecular field analysis standard model (r² = 0.755, q² = 0.505 and F = 26.70) or comparative molecular similarity indices analysis-combined steric and electrostatic fields (r² = 0.757, q² = 0.527 and F = 14.93), and survival fraction in hypoxia and comparative molecular field analysis standard model (r² = 0.736, q² = 0.521 and F = 18.63) or comparative molecular similarity indices analysis-hydrogen bond acceptor field (r² = 0.858, q² = 0.737 and F = 27.19). Categorical classification was used for the biological parameter selective cytotoxicity emerging also good models, derived by soft independent modelling of class analogy, with both comparative molecular field analysis standard model (96% of overall classification accuracy) and comparative molecular similarity indices analysis-steric field (92% of overall classification accuracy). 2D- and 3D-quantitative structure-activity relationships models provided important insights into the chemical and structural basis involved in the molecular recognition process of these phenazines as bioreductive agents and should be useful for the design of new structurally related analogues with improved potency.
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Antineoplásicos/química , Modelos Moleculares , Fenazinas/química , Relación Estructura-Actividad Cuantitativa , Diseño de FármacosRESUMEN
We have identified phenazine 5,10-dioxides as prodrugs for antitumour therapy that undergo hypoxic-selective bioreduction to form cytotoxic species. Here, we investigated some structural modifications in order to find new selective hypoxic cytotoxins and to establish the structural requirements for adequate activity. Three different chemical-series were prepared and the clonogenic survival of V79 cells on aerobic and anaerobic conditions was determined. Electrochemical- and DNA-interaction studies were done for the most relevant derivatives. The new fluoro-derivative 7-fluoro-2-aminophenazine 5,10-dioxide displayed selective toxicity towards hypoxic V79 cells having adequate hypoxic cytotoxicity ratio (HCR=6.8) and being the most potent hypoxic cytotoxins (P=2.5 µM) described for this family of bioreductive agents. The reduction potential of the N-oxide moiety in this new fluoro-derivative was in the range for adequate bioreduction property. According to the fluorescence studies, the DNA-interaction mechanism was especially operative in the phenazine drugs more than in the corresponding prodrugs, phenazine dioxides.
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Citotoxinas/química , Citotoxinas/farmacología , Hipoxia , Fenazinas/química , Fenazinas/farmacología , Animales , Línea Celular , Cricetinae , Electroquímica , Espectroscopía de Resonancia Magnética , Estructura Molecular , Espectrometría de Masa por Ionización de ElectrosprayRESUMEN
Triosephosphate isomerase from Trypanosoma cruzi (TcTIM), an enzyme in the glycolytic pathway that exhibits high catalytic rates of glyceraldehyde-3-phosphate- and dihydroxyacetone-phosphate-isomerization only in its dimeric form, was screened against an in-house chemical library containing nearly 230 compounds belonging to different chemotypes. After secondary screening, twenty-six compounds from eight different chemotypes were identified as screening positives. Four compounds displayed selectivity for TcTIM over TIM from Homo sapiens and, concomitantly, in vitro activity against T. cruzi.