Howida T. Zaky

Novel pyridazine derivatives: Synthesis and antimicrobial activity evaluation.

A general method for the preparation of new hydrazones is reported. The 1-[4-(2-methoxybenzyl)-6-aryl pyridazin-3(2H)-ylidene] hydrazines or their tautomeric structures (1(a-d)) were condensed with different aldehydes, dialdehydes, ketones, alpha-dicarbonyl compounds and simple carbohydrates to afford the hydrazones and dihydrazones (2(a-d)), (3(a-d)), (4(a-d)), (5(a-d)), (6(d)), (7(c)), (8(a-d)), (9(a-d)), (10(a-d)), (11(a-d)), (12(a,c,d)), (13(a-d)), (14(a-d)), (15(a-d)), (16(a-d)) and (17(a-d)). The structures of all synthesized compounds were confirmed from microanalytical and spectral data. Some of the products were screened for their antimicrobial activity against Staphylococcus aureus and Streptococcus faecalis, Escherichia coli and Pseudomonas aeruginosa. The hydrazone derivative 15(d) (1-[4-(2-methoxybenzyl)-6-methylphenyl pyridazin-3(2H)-ylidene]-2-(2-carboxydiphenyl methyl) hydrazine) showed the highest biological activity.

Synthesis, characterization and in vitro antimicrobial evaluation of new compounds incorporating oxindole nucleus.

New compounds incorporating with the oxindole nucleus were synthesized via the reaction of substituted isatins [5-methyl-, 5-chloro- and 1-hydroxymethyl isatins] with different nucleophiles. The structures of the newly compounds were elucidated on the basis of FTIR, 1H NMR, 13CMR spectral data, GC/MS and chemical analysis. Investigation of antimicrobial activity of the new compounds was evaluated using broth dilution technique in terms of minimal inhibitory concentration (MIC) count against four pathogenic bacteria and two pathogenic fungi. Most of the new compounds are significantly active against bacteria and fungi. MIC showed that compound (4a) possesses higher effect on Gram-positive bacteria Bacillus cereus than the selected antibacterial agent sulphamethoxazole, whereas compound (11c) possesses more activity against Gram-negative bacteria Shigella dysenterie.

Synthesis of a new class of antimicrobial agents incorporating the indolin-2-one moiety

New furanone derivatives incorporating the indolin-2-one moiety 3 were prepared via the Perkin reaction of isatins 1 with aroylpropionic acids 2 under conventional conditions or microwave irradiation. A series of functionally heterocyclic derivatives (e.g., pyridazines, pyrroles, and sulfonamides) incorporating the indolin-2-one moiety was achieved via reaction of 3 with different reagents under microwave irradiation conditions. The newly synthesized compounds were characterized on the basis of FTIR, 1H, 13C NMR and mass spectral studies. Some of the new synthesized compounds were screened for antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus), Gram-negative bacteria (Escherichia coli and Shigilla flexneri) and antifungal activity against Aspergillus flavus and Candida albicans. Compound 8 j was equipotent to chloramphenicol in inhibiting the growth of E. coli minimum inhibitory concentration (MIC 2.5 μg/mL). Compound 8j may possibly be used as a lead compound for developing a new antibacterial agents. The antibacterial activity is expressed as the corresponding MIC (μg/mL) values.

Microwave-assisted synthesis of antimicrobial agents based on pyridazine moiety

An efficient and simple microwave assisted synthesis of sulfonamide derivatives incorporating the pyridazine moiety has been developed. These sulfonamides were used for the preparation of new heterocyclic compounds via reaction with different reagents using a microwave irradiation technique. The structures of the newly synthesized compounds were confirmed on the basis of FTIR, 1H and 13C-NMR, mass spectral techniques and elemental analyses. Some of the new synthesized compounds were assayed for their in vitro antibacterial activity against Gram-positive bacteria, Staphylococcus aureus and Staphylococcus epidermidis, Gram-negative bacteria, Escherichia coli and Klebsiella pneumonia and antifungal activity against Aspergillus fumigatus and Candida albicans. Most of the new compounds showed significant antibacterial and antifungal activity.

New pyrano[2,3-c]pyridazine derivatives with antimicrobial activity synthesized using piperidine as the organocatalyst

Abstract A simple and efficient method for the synthesis of highly diverse pyrano[2,3-c]pyridazines was achieved by a one pot multicomponent reaction using piperidine as the organocatalyst. The synthesis of a series of heterocyclic derivatives with varying functionality (e.g. thiazine, tetrazole and pyrimidine) incorporating the pyrano[2,3-c]pyridazine moiety were achieved via reaction of 2a–e with different reagents. The structures of the synthesized derivatives were elucidated by FTIR, MS, 1H and 13C NMR spectroscopy. A number of the newly synthesized targeted compounds 2b–e, 3a–c and 4a–c were evaluated for their in vitro antibacterial activity and were compared with chloramphenicol and nystatin as broad spectrum reference standard antibiotics. Tests were carried out against Staphylococcus aureus (MTCC3160) and Enterococcusi fecalis as Gram-positive bacteria, and Escherichia coli (MTCC1652) and Klebsiella pneumonia as Gram-negative bacteria. Antifungal potential against Candida albicans, and Aspergillus albicans strains were also evaluated. The results revealed that compounds 3a and 3c showed strong significant activity relative to the reference against these bacterial and fungal strains.