A Mini Review on Antibacterial and Anti-Fungal Activity of Pyrazolo-Pyridazine and Pyrazolo-Cinnoline Derivatives

The in vitro antibacterial and antifungal potential of pyrazolo-pyridazine derivatives (4a-l), (4'a-l) and (4''a-m). The 3,5- Disubstitutedphenyl-3,3a,4,7-tetrahydro-2H-pyrazolo[3,4-c]pyridazine derivatives were prepared by multi-step synthesis. Reaction of benzoyl, touloyl and p-chlorobenzoyl propionic acid (1a-c) with hydrazine hydrate gave (6-phenyl, 6-touloyl and p-chlorophenyl)-tetrahydropyridazin-3-one (2a-c). This on treatment with aryl-aldehydes resulted in the formation of pyridazinone (3a-l), (3'a-l) and (3''a-m). In the final step, the pyridazinones (3a-l), (3'a-l) and (3''a-m) were reacted with hydrazine hydrate to furnish the compounds 4 (a-l), (4'a-l) and (4''a-m). These compounds were screened for in vitro antibacterial and antifungal activities. Compounds 4i, 4'f, 4''d, 4''e and 4''f was found to be significant in its action against Gram positive and Gram negative bacteria, whereas compound 4f, 4'c, 4''c and 4''d exhibited potent antifungal activity. Compound 4''l, was found to have significant action against Gram positive and Gram negative bacteria, whereas compound 4''k, exhibited potential antifungal activity. Other series of Pyridazine derivatives were synthesized by diazotization of substituted anilines followed by FriedelCrafts acylation and coupling to form corresponding hydrazones which on intra-molecular cyclization forms 3-acetyl-substitutedbenz-pyridazine-4(1H)-one. Further, condensation reaction by treatment with hydrazine hydrate yields the 3'-methyl-substituted-pyrazolo [4,3-C]Cinnolines. All cinnoline derivatives were showed good anti-fungal activity against various pathogenic bacteria and fungi. The compound 5e was found to be safe and moderate drug in comparison to standard drug.