ABSTRACT Pyrazolone is a five-membered lactam ring containing two Nitrogens and one ketonic group in its structure. Numerous pyrazolone derivatives were exhibited with diverse biological, pharmacological, and chemical applications. When pyrazolones were discovered, they were only known as NSAIDs but in recent times they play a versatile role in several complications like cerebral ischemia, cardiovascular diseases, antibacterial, antioxidant, anticancer and several other pharmacological activities. Over the last few decades, pyrazolone derivatives have been used for various biochemical applications. Some of these derivatives such as metamizole, phenazone, aminopyrine, and propyphenazone, are widely used as anti-inflammatory and analgesics. The chemistry of pyrazolone has gained increasing attention due to its diverse pharmacological properties such as anticancer, analgesic, anti-inflammatory, antimicrobial, antioxidant, antifungal, antiviral, antidiabetic, and several other biological activities. Thus, keeping because of their importance, synthetic strategies for existing as well as novel pyrazolone derivatives have been developed and explored their biochemical utility. This review deals with the various pharmacological properties of different pyrazolone derivatives and puts chemical synthetic schemes.

We report herein the synthesis and pharmacological evaluation of a new series of 6-aryl-2-(imidazol-1-yl/1,2,4-triazol-1-yl)-2-methyl-4,5-dihydro-(2H)-pyridazin-3-one (3a-j) as potential anticonvulsant and antitubercular agents. The title compounds were prepared by reacting 6-aryl-4,5-dihydro-(2H)-pyridazin-3-one (2a-e) with formaldehyde and secondary cyclic amine imidazole or 1,2,4-triazole as per Mannich reaction. Anticonvulsant activity of pyridazinone derivatives was tested at 50 mg.kg-1 dose level against maximal electroshock (MES), isoniazid (INH, 250 mg.kg-1) and pentylenetetrazole (PTZ at 80 mg.kg-1) induced seizure methods. Phenytoin sodium (25 mg.kg-1) and sodium valproate (100 mg.kg-1) were used as reference drugs for comparison purpose. In-vitro antitubercular activity was tested by Microplate Alamar Blue assay (MABA) method and the results were compared with clinically used antitubercular agents such as INH, Pyrazinamide (PZA) and Streptomycin (STM). None of the screened compounds were found to be neurotoxic at a dose level of 100 mg.kg-1. All the screened compounds (3a-j) significantly reduced the MES, INH and PTZ induced convulsions and thus showed good anticonvulsant activity. The minimum inhibitory concentration (MIC) of the title compounds against M. tuberculosis ranged from 1.6 µg/mL to 6.25 µg/mL in comparison to INH, PZA (3.125 µg/mL) and STM (6.25 µg/mL) which indicated good antitubercular activity.

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.

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.