Some divalent metal(II) complexes of salicylaldehyde‐derived Schiff bases: Synthesis, spectroscopic characterization, antimicrobial and in vitro anticancer studies

Abstract

Mononuclear transition metal(II) complexes of the type M(L)2⋅2H2O (where M = Co, Ni, Cu, Zn) have been synthesized from uninegative Schiff base ligands (HL1–HL4) designed by condensation of 4‐fluorobenzylamine with 2‐hydroxy‐1‐naphthaldehyde/3,5‐dichlorosalicylaldehyde/3,5‐dibromosalicylaldehyde/3‐bromo‐5‐chlorosalicylaldehyde. The compounds were successfully characterized using spectroscopic and physiochemical methods together with elemental analysis. Spectroscopic elucidation indicates a monobasic bidentate nature of ligands coordinated via deprotonated phenolic oxygen and azomethine nitrogen atom which suggests an octahedral geometry around the central metal ions. The complexes and ligands were screened for their in vitro antimicrobial activity against bacterial and fungal strains, the zinc(II) complexes being more active against the tested microbial strains. Further, the metal complexes were found to be more active than the uncomplexed ligands due to chelation process and, moreover, the complexes were more active against fungal strains than bacterial strains. Cytotoxic activities of all compounds were evaluated towards human alveolar adenocarcinoma epithelial cell line (A549), human breast adenocarcinoma cell line (MCF7), human prostate cancer cell line (DU145) and one normal human lung cell line (MRC‐5) using MTT colorimetric assay with doxorubicin as a standard. The zinc complexes were most active against the cancer cell lines and also found to be less toxic against MRC‐5 normal cell line than standard doxorubicin.

Synthesis, spectroscopic characterization, biological screening and in vitro cytotoxic studies of 4‐methyl‐3‐thiosemicarbazone derived Schiff bases and their Co (II), Ni (II), Cu (II) and Zn (II) complexes

“…The cytotoxicity of compounds is dependent on their ability to bind with DNA and subsequent impairment of its structure and functions followed by interference in replication and transcription process ultimately leading to cell death . Apart from this, the positive charge of the metal increases the acidity of coordinated ligands causing stronger hydrogen bonding resulting in enhanced cytotoxic activity.…”

Metal complexes of tetradentate azo‐dye ligand derived from 4,4′‐oxydianiline: Preparation, structural investigation, biological evaluation and MOE studies

“…As a consequence the coordination bonds between the azo-dye ligand and the different metal complexes may enhance the activity against various bacteria species. [49] The importance of this discussion comes from the fact that these metal complexes could reasonably be used for the treatment of some common diseases caused by E. coli, e.g. urinary tract infections, septicemia, hospital-acquired infections and gastroenteritis as previously described for analogous compounds.…”

Synthesis, spectral analysis and in vitro cytotoxicity of diorganotin (IV) complexes derived from indole‐3‐butyric hydrazide

“…Then 1 ml of stock solutions was diluted with the 9 ml of DMSO to form concentration up to 100 μg/ml. [41]…”

“…Schiff base ligands having hydrazide groups are considered as "privileged ligands" and used widely due to their easy synthetic procedure, good solubility and their novel structural features. [21][22][23][24] Schiff base ligands with indole hydrazide unit have proven to possess good biological application like antimicrobial, anticonvulsant, antihypertensive, antiplatelet aggregation, and HIV-1 reverse transcriptase inhibitor activities. [25][26][27][28][29][30][31][32][33][34] Indoles are widely distributed heterocyclic compounds having medicinal importance e.g.-Tryptophan, a natural occurring essential amino acid which is used as precursor for auxin (indole-3-acetic acid-IAA), a plant regulating hormone and used as secondary metabolites, vincristine and vindesine, natural indole alkaloids is used in treatment of leukemia and as antitumor agent, brassinin which is used against microorganism and mitomycin is natural antibiotic used as anticancer and DNA cross linking agents.…”