Summary

 

The present work deals with green condensation of two classes of aromatic heterocyclic compounds with various substituted aromatic aldehydes; the first class involves condensation of 4-amino-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one known as 4-aminoantipyrine (37) with ten different substituted benzaldehydes (17) including (benzaldehyde,
2-chloro-benzaldehyde, 2,6-dichlorobenzaldehyde, 2-fluorobenzaldehyde, 4-fluoro-benzaldehyde, 4-hydroxybenzaldehyde, 4-methoxybenzaldehyde, 3,4-dimethoxybenzaldehyde, 4-nitrobenzaldehyde, and 4-hexyloxybenz-aldehyde) to prepare 4-aminoantipyrine Schiff bases. The second class includes the reaction of 3-amino-5-methylisoxazole (88) that condensed with six various benzaldehydes (17) to synthesize the Isoxazole Schiff bases, both classes have produced excellent yields of the products in a short time at room temperature and safe procedure without utilization of any solvents, only an organic catalyst (DMEA) has been utilized to accelerate the condensation process and the highest yield in that duration of time.
The chemical structure of the products has determined and confirmed by using FT-IR, ¹H-NMR, ¹³C-NMR and CHN.

 

All the synthesized compounds have been tested for their antibacterial activity against five pathogenic bacteria (Staphylococcus aureus and Staphylococcus epidermidis) as Gram positive and (Pseudomonas aeruginosa, Salmonella abony, and Escherichia coli) as Gram negative bacteria. The results exhibited different influences, the products with fixed concentration (1000 ppm) were more effective against Gram positive than Gram negative bacteria. The compounds have inhibited the growth of bacteria and their activities were measured in mm.

Antioxidant activity for two compounds in each class;
(4-(4-fluorobenzylidene) aminoantipyrine, 55b and  4-(4-nitrobenzylidene) aminoantipyrine, 55i) in the first class and (3-(4-fluorobenzylidene)amino-5-methylisoxazole, 94b and 3-(4-nitrobenzylidene)amino-5-methyl isoxazole, 94d) in the second class with different concentrations have testes, when quercetin and ascorbic acid are used as standard antioxidant, the products have showed radical scavenging activity to withdraw the radical form the DPPH standard radical, which means the targeted Schiff bases can be used as antioxidant compounds.

 

Finally, the cytotoxic potency for two products (4-(4-fluorobenzylidene) aminoantipyrine, 55b and 3-(4-fluorobenzylidene)amino-5-methylisoxazole, 94b) have tested against human breast cancer (MCF-7) and gastric adenocarcinoma (AGS) cell lines at different concentrations and compared with the control to find their anticancer activity. The results showed lowering the effect of cancer cell lines and low toxicity of the products and can be used as anticancer drugs.