Atividade catalítica promíscua de complexos imínicos derivados de hidrazidas e aldeídos aromáticos e suas respectivas atividades anti-biofilmes

Abstract

The work deals with the synthesis of new complexes of cations of first transition metal series such as CoII, FeII, MnII and ZnII, from ligands derived from aromatic hydrazides substituted with aromatic aldehydes (2-hydroxybenzaldehyde and pyridoxal hydrochloride). The complexes obtained were structurally characterized by single crystal X-ray diffraction, spectroscopy in the ultraviolet-visible region, in the infrared region, and ¹H and ¹³C nuclear magnetic resonance. Subsequently, the compounds (ligands and complexes) were evaluated for their antioxidant activities, using the NBT (nitrotetrazolium blue chloride) photoreduction methodology. This evaluation allows the identification of compounds that have the ability to mimic the catalytic activity of the active site of the superoxide dismutase enzyme (SOD). On the other hand, the pro-oxidant activity of these compounds was evaluated through the activation of hydrogen peroxide to oxidize organic substrates such as phenol, 3,3',5,5;- tetramethylbenzidine (TMB) and o-phenylenediamine (OPD). Ten ligands were obtained with yields ranging from 84% to 94%, and from these thirteen complexes were synthesized with yields ranging from 19% to 39%. For all the synthesized compounds, the antimicrobial and antifungal activities were determined and the Minimum Inhibitory Concentrations (MICs) were obtained, as standardized by the Clinical & Laboratory Standards Institute (CLSI). To determine this susceptibility profile the broth microdilution technique was used and strains of gram-negative, gram-positive microorganisms and of the genus Mycobacterium spp. were used. To confirm the results, multi-resistant clinical isolates of the same microbial groups were used. The complexes present superior results for the catalytic mimetic activity of the active site of the superoxide dismutase enzyme when compared to the results obtained for the respective ligands, highlighting the manganese complexes (C7 and C11) synthesized from 4- aminobenzoic hydrazide and pyridoxal hydrochloride. The same behavior can be verified in the analyses of antimicrobial and pro-oxidant activity. Most of the complexes showed promising antimicrobial potential, since a varied susceptibility profile was observed for different microorganisms.