RESUMO
Introduction: The human umbilical artery (HUA), rat-isolated right atrium, and rat-isolated vas deferens present a basal release of 6-nitrodopamine (6-ND). The basal release of 6-ND from these tissues was significantly decreased (but not abolished) when the tissues were pre-incubated with Nω-nitro-L-arginine methyl ester (L-NAME). Methods: In this study, the effect of the pharmacological modulation of the redox environment on the basal release of 6-ND was investigated. The basal release of 6-ND was measured using Liquid chromatography with tandem mass spectrometry (LC-MS/MS). Results and Discussion: Pre-incubation (30 min) of the tissues with GKT137831 (1 µM) caused a significant increase in the basal release of 6-ND from all tissues. In the HUA, pre-incubation with diphenyleneiodonium (DPI) (100 µM) also caused significant increases in the basal release of 6-ND. Preincubation of the HUA with hydrogen peroxide (H2O2) (100 µM) increased 6-ND basal release, whereas pre-incubation with catalase (1,000 U/mL) significantly decreased it. Pre-incubation of the HUA with superoxide dismutase (SOD) (250 U/mL; 30 min) also significantly increased the basal release of 6-ND. Preincubation of the HUA with either allopurinol (100 µM) or uric acid (1 mM) had no effect on the basal release of 6-ND. Pre-treatment of the HUA with L-NAME (100 µM) prevented the increase in the basal release of 6-ND induced by GKT137831, diphenyleneiodonium, and H2O2. The results obtained indicate a major role of endogenous H2O2 and peroxidases as modulators of 6- ND biosynthesis/release and a lack of peroxynitrite contribution.
RESUMO
The 5-[2-ethoxy-5-(4-methylpiperazin-1-ylsulfonyl)phenyl]-1-methyl-3-propyl-1,6-dihydro-7 H-pyrazolo[4,3-d]pyrimidin-7-one, sildenafil, is a cGMP-specific phosphodiesterase-5 (PDE5) inhibitor used for penile erectile dysfunction. In the search for more potent and selective PDE5 inhibitors, new sildenafil analogues (6a-v), characterized by the presence on the sulfonyl group in the 5' position of novel N-4-substituted piperazines or ethylenediamine moiety, were prepared by traditional and microwave-assisted synthesis and tested in rabbit isolated aorta and corpus cavernosum. Similarly to sildenafil, several analogues showed IC50 values in the nanomolar range. In the in vitro studies, all the tested compounds caused concentration-dependent relaxations in both rabbit isolated aorta and corpus cavernosum. All sildenafil analogues potentiated the nitric oxide-dependent vasodilation in endothelium-intact rabbit aorta. Compound 6f exhibited great pEC50 value in corpus cavernosum, and compounds 6r and 6u in isolated aorta were found as potent as sildenafil for inhibiting PDE5. Because several analogues were significantly more lipophilic than sildenafil, these compounds may offer a new lead for development of new sildenafil analogues.
Assuntos
Disfunção Erétil/tratamento farmacológico , Inibidores da Fosfodiesterase 5 , Piperazinas/síntese química , Pirimidinas/síntese química , Sulfonas/síntese química , Animais , Aorta/efeitos dos fármacos , Aorta/fisiologia , Plaquetas/efeitos dos fármacos , Plaquetas/enzimologia , Endotélio Vascular/fisiologia , Humanos , Técnicas In Vitro , Espectroscopia de Ressonância Magnética , Masculino , Relaxamento Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Músculo Liso/fisiologia , Pênis/efeitos dos fármacos , Pênis/fisiologia , Piperazinas/química , Piperazinas/farmacologia , Purinas/síntese química , Purinas/química , Purinas/farmacologia , Pirimidinas/química , Pirimidinas/farmacologia , Coelhos , Ratos , Citrato de Sildenafila , Espectrometria de Massas por Ionização por Electrospray , Relação Estrutura-Atividade , Sulfonas/química , Sulfonas/farmacologiaRESUMO
We report microwave-assisted synthetic routes, the pharmacokinetic profile along with results from ulcerogenicity and mutagenicity studies of atenolol aspirinate, and an already described derivative, in which acetyl salicylic acid (aspirin) was connected to atenolol by an ester linkage. Atenolol aspirinate was stable towards aqueous hydrolysis but rapidly hydrolyzed in plasma (t(1/2) = 7.6 min). The results showed that the rapid and complete hydrolysis generates atenolol salicylate, which assumes a conformation stabilized by two intramolecular H-bonds, avoiding its further hydrolysis to salicylic acid and atenolol.
Assuntos
Anti-Hipertensivos/farmacocinética , Aspirina/química , Atenolol/farmacocinética , Animais , Anti-Hipertensivos/química , Anti-Hipertensivos/metabolismo , Área Sob a Curva , Atenolol/química , Atenolol/metabolismo , Mucosa Gástrica/efeitos dos fármacos , Meia-Vida , Humanos , Micro-Ondas , Modelos Moleculares , Testes de Mutagenicidade , Pró-Fármacos/química , Pró-Fármacos/metabolismo , Pró-Fármacos/farmacocinéticaRESUMO
We explored the unique substrate specificity of the primary S, subsite of human urinary kallikrein (hK1), which accepts both Phe or Arg synthesizing and assaying peptides derived from Phenylacetyl-Phe-Ser-Arg-EDDnp, a previously described inhibitor with analgesic and anti-inflammatory activities [Emim et al., Br. J. Pharmacol. 130 (2000), 1099-1107]. Phe was substituted by amino acids containing larger aliphatic or aromatic side chains as well as by non-natural basic amino acids, which were designed to combine a large hydrophobic and/or aromatic group with a positively-charged group at their side chains. In general, all peptides with basic amino acids represented better inhibitors than those with hydrophobic amino acids. Furthermore, the S1 subsite specificity proved to be much more selective than the mere distinction between Phe and Arg, for minor differences in the side chains of the non-natural amino acids resulted in major differences in the Ki values. Finally, we present a series of peptides that were assayed as competitive inhibitors for human tissue kallikrein that may lead to the development of novel peptides, which are both more potent and selective.