Latest Research News on pyrazolin : Jan 2022

Edaravone (3-Methyl-1-Phenyl-2-Pyrazolin-5-one), A Novel Free Radical Scavenger, for Treatment of Cardiovascular Diseases

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a strong novel free radical scavenger, is used for treatment of patients with acute brain infarction. Edaravone has preventive effects on myocardial injury following ischemia and reperfusion in patients with acute myocardial infarction. Antioxidant actions of edaravone include enhancement of prostacyclin production, inhibition of lipoxygenase metabolism of arachidonic acid by trapping hydroxyl radicals, inhibition of alloxan-induced lipid peroxidation, and quenching of active oxygen, leading to protection of various cells, such as endothelial cells, against damage by reactive oxygen species (ROS). Recently, we have shown that edaravone improves endothelial function through a decrease in ROS in smokers. From a clinical perspective, it is important to select an appropriate drug that is effective in improving endothelial function in patients with cardiovascular diseases. The novel free radical scavenger edaravone may represent a new therapeutic intervention for endothelial dysfunction in the setting of atherosclerosis, chronic heart failure, diabetes mellitus, or hypertension. This review focuses on clinical findings and on putative mechanisms underlying the beneficial effects of the antioxidative agent edaravone on the artherosclerotic process in patients with cardiovascular diseases.[1]

Asymmetric synthesis of pyrazoles and pyrazolones employing the reactivity of pyrazolin-5-one derivatives

Due to the frequent occurrence of the pyrazole core in many important naturally occurring and synthetic molecules, tremendous efforts have been made for their synthesis. The pyrazolin-5-one derivatives have emerged as the most effective substrates for the synthesis of useful pyrazoles and their corresponding pyrazolone derivatives. Recently, the reactivity of pyrazolin-5-ones has been used for the asymmetric synthesis of highly functionalised pyrazole and pyrazolone derivatives by employing organo- and metal-catalysts. This feature article focuses on the progress in the catalytic asymmetric synthesis of pyrazoles and pyrazolones using pyrazolin-5-one derivatives.[2]

Antioxidant activity of 3-methyl-1-phenyl-2-pyrazolin-5-one

The antioxidant activity of an anti-ischemic agent, 3-methyl-1-phenyl-2-pyrazolin-5-one (MCI-186), was examined. The pKa value of MCI-186 is 7.0 and the rate of oxidation of MCI-186 initiated with an azo compound increased with increasing pH, suggesting that the anionic form of MCI-186 is much more reactive than the non-ionic form. The major products were 3-methyl-1-phenyl-2-pyrazolin-4,5-dione (4,5-dione) and 2-oxo-3-(phenylhydrazono)-butanoic acid (OPB). Hydrolysis of 4,5-dione gave OPB. The minor intermediate product was 4-hydroxy-4-(3-methyl-1-phenyl-1H-pyrazolin-5-on-4-yl)-3-methyl-1-phenyl-1H-pyrazolin-5-one (BPOH). The nucleophilic attack of the anionic form of MCI-186 to 4,5-dione is likely to give BPOH. MCI-186 (50 μM) inhibited the aerobic oxidation at 37°C of 5.2 mM unilamellar soybean phosphatidylcholine (PC) liposomal membranes, initiated with a water-soluble initiator, as efficientlyas did ascorbate (100 μM). MCI-186 (50 μM) also inhibited the oxidation of the same PC liposomal membranes, this time initiated with a lipid-soluble initiator, almost as efficiently as did α-tocopherol (2 μM). Furthermore, the combination of MCI-186 with ascorbate or α-tocopherol showed almost complete inhibition of PC oxidation induced by both initiators.[3]

Synthesis and Charaterization of Metal Chelates of (5-(2,3-dimethyl-1-phenyl-3-pyrazolin-5-one-4-ylazo)-1H-pyrimidine-2,4-dione)

An azo dye UAAP and Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)complexes were synthesized and characterized using elemental analysis, mass spectra, UV- Vis, fluorescence spectra, ESR spectrum, IR spectra, NMR spectra, NLO property, molar conductance and magnetic measurements. The spectral and analytical data reveal that UAAP act as both bidentate and tridentate ligand. The molar conductance data reveal that complexes Co(II), Cu(II) and Zn(II) are nonelectrlytic and Mn(II), Ni(II) 1:2 electrolyte in nature. Based on all data structures were proposed for UAAp and complexes. The UAAP and metal complexes were screened for antimicrobial activity, antioxidant study, DNA cleavage analysis and anticancerous investigation.[4]

Synthesis, Characterization and Biological Studies of Some Transition Metal Complexes with 5-(4-bromophenyl)-3-(thiophen-2-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide Ligand

A 2-pyrazoline based bi dentate ligand 3-(2-thiophen-2-yl)-5-(4-bromophenyl)-1-carbothiomyl-2-pyrazoline has been synthesized by Claisen-Schmidt condensation of 2-acetylthiophene with 4-bromo benzaldehyde followed by cyclization of the resulting chalcone with thiosemicarbazide. The chromium(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of the new pyrazoline based-ligand were prepared by the direct reaction of their hydrated metal chlorides with the free ligand and separated in solid state. The metal complexes were characterized by (C.H.N.S) elemental analysis, FT-IR, UV-Vis, 1H, 13C NMR and mass spectra. As well as the molar conductance measurements in DMSO solutions suggested non-electrolytic nature of all complexes except chromium(III) complexes which was electrolyte in 1:1 ratio supporting the proposed formula of the complexes [ML2Cl2] M= Mn, Co, Ni, Cu, Zn(II) and [CrL2Cl2]Cl. The solution of ligand and it’s metal complexes were investigated for their ability to kill Esherichia coli and Staphylococcus aureas bacteria, Candida albicans and Burkholderia cepacia via diffusion method. It is found from biological results that the copper(II) and zinc(II) complexes showed high inhibition for bacteria growth with compared to the antibiotic drug. However, the free ligand in DMSO exhibited highest inhibition in 12 mm zone compared with its complexes. The resulted obtained showed that the Mn(II), Co(II), Cu(II) and Ni(II) complexes showed medium activity whereas the chromium(III) complex showed inhibition zone toward in the range (18-22) against Esherichia coli and Burkholderia cepacia.[5]


[1] Higashi, Y., Jitsuiki, D., Chayama, K. and Yoshizumi, M., 2006. Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a novel free radical scavenger, for treatment of cardiovascular diseases. Recent Patents on Cardiovascular Drug Discovery (Discontinued), 1(1), pp.85-93.

[2] Chauhan, P., Mahajan, S. and Enders, D., 2015. Asymmetric synthesis of pyrazoles and pyrazolones employing the reactivity of pyrazolin-5-one derivatives. Chemical Communications, 51(65), pp.12890-12907.

[3] Yamamoto, Y., Kuwahara, T., Watanabe, K. and Watanabe, K., 1996. Antioxidant activity of 3-methyl-1-phenyl-2-pyrazolin-5-one. Redox Report, 2(5), pp.333-338.

[4] Vidya, V.G., 2018. Synthesis and Charaterization of Metal Chelates of (5-(2, 3-dimethyl-1-phenyl-3-pyrazolin-5-one-4-ylazo)-1H-pyrimidine-2, 4-dione). International Research Journal of Pure and Applied Chemistry, pp.1-15.

[5] Aljibouri, M.N.A. and Neamah, G.K., 2016. Synthesis, Characterization and Biological Studies of Some Transition Metal Complexes with 5-(4-bromophenyl)-3-(thiophen-2-yl)-4, 5-dihydro-1H-pyrazole-1-carbothioamide Ligand. International Research Journal of Pure and Applied Chemistry, pp.1-13.

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