Synthesis, In Vitro Biological Evaluation and In Silico Studies of Some New Heterocyclic Schiff Bases

Abstract

2‐Hydroxy‐naphthaldehyde based heterocyclic Schiff base derivatives (1 a‐1 h) were prepared and characterized by multi‐spectroscopic techniques and elemental analysis. Antibacterial activity of all the compounds was tested against Streptococcus pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, Salmonella enterica, Klebsiella pneumoniae and Escherichia coli bacterial strains. The antifungal potential of the synthesized compounds was also tested against three Candida strains (Candida albicans, Candida glabrata and Candida tropicalis). In the antibacterial activity, the compounds showed high MIC values and thus found less potent against all the tested bacterial strains. Interestingly, compounds 1 b and 1 c exhibited significant activity with MIC 125 μg/ml against all the tested fungal strains. Hemolytic assay against human RBCs revealed that compounds 1 b and 1 c showed less toxicity than the standard drug fluconazole at each tested concentration (25‐1000 μg/ml). In growth kinetics studies, compounds 1 b and 1 c significantly inhibited the growth of Candida cells at 2MIC and MIC concentrations. The interaction ability of lead compounds (1 b and 1 c) with Ct–DNA was carried out by absorption, fluorescence, hydrodynamic, cyclic voltammetery measurements and circular dichroism. Results suggested that compound 1 b and 1 c bind to Ct–DNA via an intercalative mode supported by molecular docking studies. The antioxidant potential of heterocyclic derivatives 1 b and 1 c was estimated by DPPH free radical and hydrogen peroxide assay which confirm that compounds exhibited significant antioxidant activity.

Green Synthesis Strategy for New Schiff‐Base Complexes: Characterization, Conductometry, In Vitro Assay Confirmed by In Silico Approach

“…complexes, respectively. From these straight lines and Gibbs free energies of formation, the formation constants between metal salts and ligand were calculated for each kind of complex (Tables 4S) by using of equation (13) and (14) respectively. The association free energies estimated are small and spontaneous, which prove presence of electrostatic attraction force in solution.…”

“…[11b] Furthermore Zn(II) and Cu (II) complexes derived from aminoalcohol ligand exhibited photoluminescence properties, [12a] while two heteronuclear Fe (III)-Schiff base complexes were deliberately characterized by practical and computational tools. [12b] Moreover, in-vitro and insilico assays for Schiff bases were executed, [13] whereas distorted homodinuclear Cu(II) complexes were prepared from triethanolamine and displayed DNA binding efficiency [13] in addition to N-subistituted 1,2,3 triazolyl. [14] Accordingly, transition metal ion complexes in nanoparticle scale have high biological efficiency, especially those that are prepared in an efficient and hazard-less manner.…”

Controllable Synthesis and Biological Application of Schiff Bases from d-Glucosamine and Terephthalaldehyde

“… 2 − 4 The Schiff base is not only used as a pigment, dye, catalyst, intermediate in organic synthesis, a supercapacitor, and so on 5 − 8 but also shows a wide range of biological activities, including anti-fungal, anti-bacterial, anti-malaria, anti-proliferation, anti-inflammatory, anti-virus, etc. 9 − 13 …”

“…Thus, this kind of compound is hereafter called the Schiff base. It refers to the reaction between a class of compounds containing aldehydes and the others with amino groups, which results in imine groups (CN). − The Schiff base is not only used as a pigment, dye, catalyst, intermediate in organic synthesis, a supercapacitor, and so on − but also shows a wide range of biological activities, including anti-fungal, anti-bacterial, anti-malaria, anti-proliferation, anti-inflammatory, anti-virus, etc. − …”