Analgesic and anti-inflammatory activities of several 4-substituted-6-(3'-nitrophenyl)pyridazin-(2H)-3-one derivatives

Several 6-aryl-4-substituted benzylidene/furfurylidene pyridazin(2H)-3-one derivatives (4a-f) were synthesized and evaluated as analgesic and anti-inflammatory agents in mice and rats, respectively. All compounds were tested by using Eddy's hot plate and the carrageenan-induced hind paw oedema method for the evaluation of analgesic and anti-inflammatory activities, respectively. Results showed that compounds 4f, 4b, 4d, and 4e exhibited higher analgesic and anti-inflammatory activities than other remaining compounds. All title compounds (4a-f) were characterized by IR, NMR and Mass spectroscopy.

Diversos derivados benzilideno/furfurilideno piridazin(2H)-3-ona 6-aril-4-substituídos (4a-f) foram sintetizados e avaliados como analgésicos e anti-inflamatórios em camundongos e ratos, respectivamente. Todos os compostos foram testados utilizando-se o método de placa quente de Eddy e o de edema de pata induzido por carragenana para a avaliação das atividades analgésica e anti-inflamatória, respectivamente. Os resultados mostraram que os compostos 4f, 4b, 4d e 4e exibiram atividade analgésica e anti-inflamatória mais alta do que os compostos restantes. Todos os compostos (4a-f) foram caracterizados por IV, RMN e espectrometria de massas.

Tautomerism and isotopic multiplets in the 13C NMR spectra of partially deuterated 3-arylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-diones and their sulfur analogs--evidence for elucidation of the structure backbone and tautomeric forms.

The tautomerism of the synthesized 3-arylpyrimido[4,5-c]pyridazine-5,7(6H,8H)-diones (1a-d) and 3-aryl-7-thioxo-7,8-dihydro-6H-pyrimido[4,5-c]pyridazine-5-ones (2a-d) was studied in dimethyl sulfoxide (DMSO)-d(6). (1)H NMR spectra of 1a-d showed a clustered water molecule in the structure backbone that is attached by strong intermolecular H bonding. The relation between the temperature and H bonding of the clustered water molecule with 1a was also studied as representative. The relation between the electronegativity (chi) of the substituent on phenyl ring and the chemical shifts of clustered water protons in 1a-d was also studied. All of 1a-d and also 2d compounds existed in lactam (I) form, whereas 2a-c compounds have two distinguished tautomers in DMSO-d(6) [lactam (I) and lactim (II) forms]. The solvent-substrate proton exchange was examined in compounds 1a-d and 2a-d by adding one drop of D(2)O. All compounds (except 1d) showed proton/deuterium exchange of the clustered water protons in DMSO by adding one drop of D(2)O. Some compounds (but not all of them) that are easily soluble in DMSO-d(6) containing D(2)O showed isotopic splitting (beta-isotope effect) in their (13)C NMR spectra. Among them, compound 1a was the best evidence to help the spectral assignments and structure determination of predominant tautomer by carbon-13 splitting (beta-isotope effect).

Human recombinant monoamine oxidase B as reliable and efficient enzyme source for inhibitor screening.

Interest in inhibitors of monoamine oxidase type B (MAO B) has grown in recent years, due to their therapeutic potential in aging-related neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. This study is devoted to the use of human recombinant MAO B obtained from a Baculovirus expression system (Supersomes MAO B, BD Gentest, MA, USA) as reliable and efficient enzyme source for MAO B inhibitor screening. Comparison of inhibition potencies (pIC50 values) determined with human cloned and human platelet MAO B for the two series of MAO B inhibitors, coumarin and 5H-indeno[1,2-c]pyridazin-5-one derivatives, showed that the difference between pIC50 values obtained with the two enzyme sources was not significant (P>0.05, Student's t-test). Hence, recombinant enzyme is validated as convenient enzyme source for MAO B inhibitor screening.

Mechanism of action of pyridazine analogues on protein tyrosine phosphatase 1B (PTP1B).

The inhibitory effect on PTP1B caused by the addition of pyridazine analogues has been investigated. Biophysical techniques, that is, mass spectrometry (MS), nuclear magnetic resonance (NMR), and isothermal titration calorimetry (ITC) were used for the characterization. Pyridazine analogues cause catalytic oxidation of the reducing agent, generating hydrogen peroxide that oxidizes the active site cysteine on the enzyme, leading to enzyme inactivation. Two additional compound classes show the same effect. We found one common structural feature in these molecules that allows the reaction with triplet molecular oxygen to be less endothermic. A proposed mechanism for the catalytic redox cycle is described.