Synthesis, Characterization, Mechanism and Biological Evaluations of 1,2,4 - Triazole - Containing Schiff Bases, Hemiaminals and Their Metal Complexes
Here, we describe the syntheses of four Schiff Bases, four Hemiaminals and three metal (Cu(II), Ni(II) and Co(II)) complexes from phenanthroline dialdehyde and di-pyridylaldehydes with 4-amino-3,5-dimethyl-1,2,4-triazole. Various spectroscopic methods have been used to determine the structures. The effect of solvents and reactant concentrations on these hemiaminals formation have been studied. Stability of these hemiaminals have also been studied both in solution in DMSO and in solid form. Hemiaminal 10 synthesized from phenanthroline dialdehyde 1 was more stable in DMSO than hemiaminals 11, 12 and 13 synthesized from di-pyridylaldehydes (2, 3 and 4). But in solid form, these hemiaminals are similarly stable. The results indicated that hydrogen bonding plays a key role on the formation and stabilization of these hemiaminals. The synthesized Schiff bases 6, 7, 8 and 9 and Hemiaminal 10 were tested in vitro to study their cytotoxicity and anti-oxidative activity in human lung carcinoma (A549), breast carcinoma (BT549), prostate adenocarcinoma (PC3) and mouse preadipocytes (3T3- L1) cells. Compounds 6 and 10 synthesized from phenanthroline dialdehyde 1 were found to increase Glutathione (GSH) level slightly in all four cell lines. Schiff base 9 synthesized from [2,2’-Bipyridine]-6,6’-dicarboxaldehyde 4 showed better selectivity and cytotoxicity against both BT549 and A549 cells compared to the anticancer drug tamoxifen. The compound 9 can also activate caspase 9 to induce apoptosis in BT549 and A549 cells. The metal complexes 14, 15 and 16 were also tested for their antibacterial activities against three gram positive bacterial strains ( E. coli MC4100, E. coli DH5α and Listeria monocytogenes) and two gram negative bacterial strains ( Staphylococcus aureus and Bacillus subtilus). The zone of inhibition and minimum inhibition concentration (MIC) were observed for these three metal complexes against the tested bacterial strains. The nickel complex 15 was more active among these three metal complexes against the tested bacterial strains with MIC in the range of 20 – 30 μM.
Md Shafiqul Islam,
"Synthesis, Characterization, Mechanism and Biological Evaluations of 1,2,4 - Triazole - Containing Schiff Bases, Hemiaminals and Their Metal Complexes"
ETD Collection for Tennessee State University.