RESUMO
Selective androgen receptor modulators (SARMs) represent an emerging class of drugs likely to be abused in sport. For clinical applications, these substances provide a promising alternative to testosterone-replacement therapies and their advantages include oral bioavailability, androgen receptor specificity, tissue selectivity, and the absence of steroid-related side effects. Although not yet commercially available, since January 2008 SARMs have been included on the prohibited list issued yearly by the World Anti-Doping Agency (WADA), so control laboratories need to update their procedures to detect either the parent drugs or their metabolites. Within this context, two quinolinone SARM models were synthesized and automatically characterized to update the existing routine screening procedures. The conditions for the new target analytes are compatible with the existing laboratory protocols used for both in-competition and out-of-competition controls and can be included in them. Validation parameters according to ISO 17025 and WADA guidelines were successfully determined. For analytical determinations, spiked urine samples were hydrolyzed and extracted at pH 9.6 with 10 mL of tert-butyl methyl ether. Then, the analytes were subsequently converted into trimethylsilyl derivatives and detected by gas chromatography-mass spectrometry. The absence of interferents, together with excellent repeatability of both retention times and the relative abundances of diagnostic ions, allowed proper identification of all SARM analytes. The analytes' quantification was linear up to 500 ng/mL and precision criteria were satisfied (coefficient of variation less than 25% at 10 ng/mL). The limits of detection were 1 ng/mL for both SARMs, whereas recovery values were between 95.5 and 99.3%. The validated method can be efficiently used for urine screening of the 2-quinolinone-derived SARMs tested.
Assuntos
Dopagem Esportivo , Cromatografia Gasosa-Espectrometria de Massas/métodos , Quinolonas/análise , Receptores Androgênicos/efeitos dos fármacos , Humanos , Limite de Detecção , Espectroscopia de Ressonância Magnética , Padrões de Referência , Reprodutibilidade dos TestesRESUMO
The design of new vasodilator derivatives in which two different pharmacophoric groups are present in a single molecule has been pursued by substitution of NO-prodrug furoxan moieties for the furanylcarbonyl function in Prazosin, a well-known alpha 1-receptor antagonist. The aim was to obtain new antihypertensive agents in which two vasodilation mechanisms, alpha 1-antagonist and NO-mediated, can operate in an appropriate balance. The alpha 1-antagonist activity was assessed on rat aortic strips in the presence and in the absence of oxyhemoglobin (HbO2), a well-known scavenger of nitric oxide. The resulting hybrids displayed different pharmacological behaviors. When the 4-furoxanylcarbonyl system, bearing an ester or an amide function at the 3-position, was present (derivatives 7a,b), hybrids with predominant alpha 1-antagonist activity were obtained. By contrast, in the derivative 7c, in which the nitrile function is linked to the 3-position of the furoxan ring, the NO-mediated vasodilating properties are predominant. Finally, the (furoxanylsulfonyl)piperidine derivatives 13a,b showed NO vasodilation and alpha 1-antagonist activities in an appropriate balance. For the furoxan derivatives, the NO-dependent vasodilating ability, assessed on the K(+)-depolarized aortic strip, and the NO release features under the action of thiol cofactors are also discussed.
Assuntos
Antagonistas Adrenérgicos alfa/farmacologia , Anti-Hipertensivos/farmacologia , Óxido Nítrico/farmacologia , Oxidiazóis/farmacologia , Vasodilatadores/farmacologia , Antagonistas Adrenérgicos alfa/síntese química , Animais , Anti-Hipertensivos/química , Aorta , Cisteína/farmacologia , Técnicas In Vitro , Espectroscopia de Ressonância Magnética , Masculino , Contração Muscular/efeitos dos fármacos , Óxido Nítrico/metabolismo , Norepinefrina/farmacologia , Oxidiazóis/síntese química , Oxiemoglobinas/farmacologia , Prazosina/análogos & derivados , Prazosina/síntese química , Ratos , Relação Estrutura-AtividadeRESUMO
Racemic methyl 1,4-dihydro-2, 6-dimethyl-5-nitro-4-(benzofurazanyl)pyridine-3-carboxylates (+/-)-10 and (+/-)-11 and their benzofuroxanyl analogues (+/-)-12 and (+/-)-13 were prepared using a modified Hantzsch reaction that involved the condensation of nitroacetone with methyl 3-aminocrotonate and the appropriate aldehydes. The racemic mixtures were resolved into the corresponding enantiomers. Whole-cell voltage-clamp studies on L-type Ca2+ channels expressed in a rat insulinoma cell line (RINm5F) showed that all the dextrorotatory antipodes were effective agonists of L-type Ca2+ currents, while the levorotatory ones were weak Ca2+ entry blockers. The (+)-enantiomer of benzofurazan-5'-yl derivative 11 demonstrated unusual activity in that, in addition to producing a potentiation of L-type currents, it interfered with the voltage-dependent gating of L-type channels by producing a net delay of their activation at low voltages. This compound represents an interesting tool to probe L-type Ca2+ channel structure and function.
Assuntos
Benzoxazóis/síntese química , Agonistas dos Canais de Cálcio/síntese química , Bloqueadores dos Canais de Cálcio/síntese química , Canais de Cálcio/efeitos dos fármacos , Piridinas/síntese química , Animais , Benzoxazóis/química , Benzoxazóis/farmacologia , Agonistas dos Canais de Cálcio/química , Agonistas dos Canais de Cálcio/farmacologia , Bloqueadores dos Canais de Cálcio/química , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio/fisiologia , Canais de Cálcio Tipo L , Ativação do Canal Iônico , Técnicas de Patch-Clamp , Piridinas/química , Piridinas/farmacologia , Ratos , Estereoisomerismo , Células Tumorais CultivadasRESUMO
A series of analogues of prazosin, in which 1-methyl or 1-phenylpyrazole moieties were substituted for the furan ring, were synthesized and studied for their alpha 1-adrenoceptor antagonist activity. The role of the five member heterocyclic substructures in determining the affinity for the alpha 1-receptor is briefly discussed.
Assuntos
Antagonistas Adrenérgicos alfa/química , Antagonistas Adrenérgicos alfa/síntese química , Prazosina/análogos & derivados , Pirazóis/química , Pirazóis/síntese química , Antagonistas Adrenérgicos alfa/farmacologia , Animais , Modelos Moleculares , Músculo Liso Vascular/efeitos dos fármacos , Pirazóis/farmacologia , Ratos , Relação Estrutura-AtividadeRESUMO
Synthesis and structural characterization of some ring-open analogues of Prazosin containing either the guanidine substructure or urea-equivalent groups are described. The opening of the pyrimidine ring in Prazosin is very important as far as the affinity for alpha 1-adrenoceptor is concerned. The pA2 values of the ring-open derivatives are 10(4)-10(5) fold lower than that of the parent. It is probable that the affinity decrease principally reflects a negative influence of the conformational factors in the interaction with the alpha 1-receptor. The derivative 5 containing the guanidine moiety, charged at physiological pH, is as active as the other derivatives containing the uncharged urea-equivalent groups. This behaviour indicates, in this class of compounds, the importance of H-bonding interactions with the receptor. When in the ring-open models the ethanediamino substructure is substituted for the piperazine ring additional decrease in activity occurs.
Assuntos
Antagonistas de Receptores Adrenérgicos alfa 1 , Prazosina/análogos & derivados , Prazosina/farmacologia , Animais , Aorta Torácica/efeitos dos fármacos , Cobaias , Técnicas In Vitro , Masculino , Músculo Liso Vascular/efeitos dos fármacos , Ratos , Ducto Deferente/efeitos dos fármacosRESUMO
PURPOSE: To obtain new cardiovascular agents with mixed Ca2+-channel antagonistic and NO-donor properties, a series of "hybrid" 1,4-dihydropyridines (1,4-DHPs), bearing NO-donating furoxan moieties on the 3-positioned lateral ester chain were synthesized and pharmacologically characterized. Furazan analogues were also prepared and investigated for control purposes, because they are unable to release NO. METHODS: Synthesis of the models was achieved by a modified Hantzsch approach. All of the final furoxan 1,4-DHPs were assessed for their ability to produce nitrite in the presence of a large excess of cysteine by the Griess reaction. Vasodilating activity was evaluated on rat aorta and expressed as EC50 and EC50MB values, obtained in the absence and in the presence of methylene blue (MB) respectively, a well-known guanylate cyclase inhibitor. Affinities to 1,4-DHP receptor on Ca2+-channels, expressed as IC50 values, were determined through displacement experiments of [3H]-nitrendipine on rat cortex homogenates. RESULTS: Some hybrid compounds (derivatives 15a, 15b, 16a, and 16b) displayed vasodilating activity depending predominantly on their Ca2+-channel blocker properties. By contrast, some others (derivatives 17a, 17b, and 21) behaved as well-balanced hybrids with mixed Ca2+-channel blocking and NO-dependent vasodilating activities. CONCLUSION: This work demonstrates the possibility of obtaining well-balanced hybrids endowed with mixed NO-donor and Ca2+-channel blocker properties using appropriate 1,4-DHP and furoxan moieties. A procedure for the individual evaluation of the NO-dependent vasodilator component and that due to Ca2+-channel blocking is proposed.
Assuntos
Bloqueadores dos Canais de Cálcio/síntese química , Fármacos Cardiovasculares/síntese química , Di-Hidropiridinas/síntese química , Doadores de Óxido Nítrico/síntese química , Óxido Nítrico/metabolismo , Animais , Aorta/efeitos dos fármacos , Aorta/fisiologia , Bloqueadores dos Canais de Cálcio/química , Bloqueadores dos Canais de Cálcio/farmacologia , Fármacos Cardiovasculares/química , Fármacos Cardiovasculares/farmacologia , Di-Hidropiridinas/química , Di-Hidropiridinas/farmacologia , Relação Dose-Resposta a Droga , Masculino , Doadores de Óxido Nítrico/química , Doadores de Óxido Nítrico/farmacologia , Ratos , Ratos Wistar , Vasodilatação/efeitos dos fármacos , Vasodilatadores/síntese química , Vasodilatadores/química , Vasodilatadores/farmacologiaRESUMO
The synthesis and in vitro vasodilating properties of hybrid compounds in which furoxan (1,2,5-oxadiazole 2-oxide) moieties, endowed with different NO-donor properties, were substituted for the nitroxy function of Nicorandil are reported. The corresponding cyanoguanidine analogues are also considered. This approach has led to a series of vasorelaxing compounds devoid of affinity for K(ATP) channels, whose activity is prevalently due to their ability to activate sGC, at the concentrations of the experiments. Related furazan (1,2,5-oxadiazole) derivatives, unable to release nitric oxide were also prepared and studied for control. The amide analogues of Nicorandil display feeble vasorelaxing action not involving the activation of K+ channels, while in the guanidine analogues, this mechanism seems to underlie this action.
Assuntos
Nicorandil/farmacologia , Oxidiazóis/farmacologia , Animais , Aorta Torácica/fisiologia , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/fisiologia , Guanidinas/síntese química , Guanidinas/farmacologia , Concentração Inibidora 50 , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Nicorandil/análogos & derivados , Nicorandil/síntese química , Doadores de Óxido Nítrico/síntese química , Óxidos de Nitrogênio/metabolismo , Ressonância Magnética Nuclear Biomolecular , Oxidiazóis/síntese química , Canais de Potássio/efeitos dos fármacos , Cloreto de Potássio/farmacologia , Ratos , Ratos Wistar , Vasodilatação/efeitos dos fármacos , Vasodilatadores/síntese química , Vasodilatadores/farmacologiaRESUMO
PURPOSE: A series of derivatives having a propranolol-like moiety linked to NO-donor furoxan substructures were synthesized. The main objective of this investigation was to obtain agents with mixed NO-dependent vasodilating and beta-blocking activities. METHODS: Most of the target compounds were synthesized from the appropriate furoxans bearing XCH2CH2NH2 (X = O, S, SO2) chains at the 4 position of the ring, using Al(C2H5)3 in methylene chloride solution and (+/-)2,3-epoxypropyl 1-naphtyl ether. Two of the final products (X = CONH) were obtained by coupling the appropriate furoxancarboxylic acids with N-[2-hydroxy-3-(1-naphthoxy)propyl]-ethylenediamine. beta 1- and beta 2-blocking activities were examined on isolated guinea pig right atria and on guinea pig trachea respectively. Vasodilating properties were assessed on endothelium denuded strips of rat aorta. RESULTS: Some derivatives behave as well balanced "hybrids" displaying NO-dependent vasodilating and beta-blocking properties in the same concentration range. Some others display either prevalent beta-blocking or vasodilating activity. Generally speaking hybrid formation lowers the affinity for beta-receptors, in particular for beta 2-type, to give an increase in beta 1/beta 2 selectivity. CONCLUSIONS: The furoxan system is a flexible tool in designing analogues of propranolol whose NO-donating and beta-blocking properties are modulated over a wide range.
Assuntos
Antagonistas Adrenérgicos beta/farmacologia , Coração/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Óxido Nítrico/metabolismo , Traqueia/efeitos dos fármacos , Vasodilatadores/farmacologia , Antagonistas Adrenérgicos beta/síntese química , Animais , Desenho de Fármacos , Cobaias , Técnicas In Vitro , Masculino , Contração Muscular/efeitos dos fármacos , Relaxamento Muscular/efeitos dos fármacos , Oxidiazóis/química , Propranolol/química , Ratos , Ratos Wistar , Receptores Adrenérgicos beta 1/efeitos dos fármacos , Receptores Adrenérgicos beta 2/efeitos dos fármacos , Vasodilatadores/síntese químicaRESUMO
We demonstrate experimentally that, in a paraelectric, nonstationary boundary conditions can dynamically halt the intrinsic instability of quasi-steady-state photorefractive self-trapping, driving beam evolution into a stable oscillating two-soliton-state configuration.
RESUMO
PURPOSE: Model compounds containing NO-donor furoxan moieties at the 3-positioned basic lateral chain of 1, a 1,4-dihydropyridine related to nicardipine, were synthesized in order to study their vasodilating activity as well as their basic and lipophilic behaviour. METHODS: All the compounds were obtained by a modified Hantzsch approach. Potentiometry was used to determine pKa and lipophilicity descriptors. The furoxan 4-aryl-1,4-dihydropyridines were assessed for their ability to release nitrite, in the presence of a large excess of cysteine, by the Griess reaction. Vasodilating activity of the products in the absence and in the presence of ODQ, a well-known guanylate cyclase inhibitor, was evaluated on rat thoracic aorta. RESULTS: The compounds display low basicity values and for this reason their log Ds at physiological pH are identical to the log Ps of the neutral forms. Products 2, 3 display vasodilating action principally dependent on their Ca2+-antagonist properties, whereas 4 behaves as a well-balanced hybrid with mixed Ca2+-channel blocker and NO-dependent vasodilator activities. CONCLUSIONS. Nitrogen containing lateral chain at the 3-position of 1 is a suitable molecular region to be modified in order to obtain well-balanced furoxan NO-donor 1,4-DHPs. This manipulation produces a decrease in the basicity. General analysis of pKa and lipophilicity descriptors of these new DHPs suggest that molecular flexibility could influence both their basicity and log PI.
Assuntos
Bloqueadores dos Canais de Cálcio/síntese química , Di-Hidropiridinas/síntese química , Doadores de Óxido Nítrico/síntese química , Animais , Aorta Torácica/efeitos dos fármacos , Aorta Torácica/fisiologia , Bloqueadores dos Canais de Cálcio/química , Bloqueadores dos Canais de Cálcio/farmacologia , Di-Hidropiridinas/química , Di-Hidropiridinas/farmacologia , Relação Dose-Resposta a Droga , Nicardipino/química , Nicardipino/farmacologia , Óxido Nítrico/biossíntese , Doadores de Óxido Nítrico/química , Doadores de Óxido Nítrico/farmacologia , Ratos , Vasodilatação/efeitos dos fármacos , Vasodilatação/fisiologiaRESUMO
The inhibition mechanism of the dimeric human placenta glutathione transferase (GST) P1-1 by calvatic acid and the reaction intermediates, i.e. the diazocyanide analogue of calvatic acid, has been investigated at pH 7.0 and 30.0 degrees C. Experiments performed at different molar ratios of inhibitor/GST P1-1 indicate that 1 mol calvatic acid inactivates 1 mol GST P1-1, containing two catalytically equivalent active sites. However, 2 mol of the diazocyanide analogue of calvatic acid inactivate 1 mol GST P1-1. Two disulfide bridges/dimer, probably between Cys47 and Cys101, have been formed during the reaction of GST P1-1 with calvatic acid and its diazocyanide analogue. The apparent second-order rate constants for GST P1-1 inactivation by calvatic acid and its diazocyanide analogue are 2.4+/-0.3 M(-1) s(-1) and (8.5+/-0.7) x 10(3) M(-1) s(-1), respectively. The reaction of calvatic acid with free L-cysteine can be described by a simple process with an apparent second-order rate constant of (5.0+/-0.4) x 10(1) M(-1) s(-1). In contrast, a transient species occurs during the reaction of the diazocyanide analogue of calvatic acid with free L-cysteine. Kinetics may be described by a second-order process [the rate constant being (8.0+/-0.5) x 10(3) M(-1) s(-1)] followed by a first-order decay [the rate constant corresponding to (1.2+/-0.1) x 10(1) s(-1)]. Calvatic acid represents an enzyme inhibitor acting much slower than its reaction intermediates (i.e. its diazocyanide analogue).
Assuntos
Antibacterianos/farmacologia , Glutationa Transferase/antagonistas & inibidores , Isoenzimas/antagonistas & inibidores , Placenta/enzimologia , Benzoatos/química , Benzoatos/farmacologia , Cianetos , Inibidores Enzimáticos/farmacologia , Feminino , Glutationa S-Transferase pi , Humanos , Cinética , Nitrilas/química , Nitrilas/farmacologia , GravidezRESUMO
The synthesis, structural characterization, NO-donor properties, and in vitro vasodilating activities of a series of furoxancarbonitriles 2, 17-22a, b are reported. Some derivatives (2b, 2a, 18b, 21b, 22b) are more potent vasodilating agents than sodium nitroprusside (SNP), the reference compound, some others display similar potency (17b, 19b, 20b). Log EC50 values fit well on the linear correlation log EC50 versus log C0.1(1 min) (namely the logarithm of the concentration able to release 2.6 mumol l-1 min-1 of NO) found in a previous work. The haemodynamic profile in anaesthetised pigs for some selected derivatives (2a, b, 19a, b) is also presented. These profiles are consistent with that known for another furoxan NO-donor (4-hydroxymethyl-3-furoxancarboxamide, CAS 1609) and suggest similar characteristic of in vivo NO-release.
Assuntos
Hemodinâmica/efeitos dos fármacos , Nitrilas/síntese química , Oxidiazóis/síntese química , Vasodilatadores/síntese química , Animais , Aorta Torácica/efeitos dos fármacos , Técnicas In Vitro , Intubação Gastrointestinal , Espectroscopia de Ressonância Magnética , Masculino , Espectrometria de Massas , Músculo Liso Vascular/efeitos dos fármacos , Óxido Nítrico/química , Nitrilas/farmacologia , Oxidiazóis/farmacologia , Ratos , Ratos Wistar , Suínos , Vasodilatadores/farmacologiaRESUMO
PURPOSE: The objective of this study was to compare and interpret the variations in lipophilicity of homologous (p-methylbenzyl)alkylamines (MBAAs) in isotropic (octanol/water) and anisotropic (zwitterionic liposomes/water) system. METHODS: Two experimental approaches were used, namely the pH-metric method to measure lipophilicity parameters in octanol/water and liposomes/water systems, and changes in NMR relaxation rates to validate the former method and to gain additional insights into the mechanisms of liposomes/water partitioning. RESULTS: For long-chain homologues (N-butyl to N-heptyl), the octanol/water and liposomes/water systems mostly expressed hydrophobicity. In contrast, the lipophilicity of the shorter homologues (N-methyl to N-propyl) in the two systems expressed various electrostatic and polar interactions. CONCLUSIONS: The study sheds light on the molecular interactions between zwitterionic liposomes and amphiphilic solutes in neutral and cationic form.