Síntese e caracterização de complexos de Cu(II), Ag(I) E Zn(II) com tripeptídeos: avaliação de atividade com xanthomonas citri subsp. citri

Abstract

SYNTHESIS AND CHARACTERIZATION OF Cu (II), Ag (I) AND Zn (II) COMPLEXES WITH TRIPEPTIDE LIGANDS: ACTIVITY EVALUATION IN XANTHOMONAS CITRI SUBSP. CITRI. In the search for new active substances against phytopathogens, were synthesized and characterized metal complexes with tripeptide L-Phenylalanine-Glycyl-Glycine (PGG), with general formula [Metal (PGG)]counterion, (PGG-1, PGG-2, PGG-3 and PGG-4), and the tripeptide Glycine-Glycyl-L-Histidine (GGH) of general formula [Metal (GGH)] (GGH-1, GGH-2, GGH-3 and GGH-4). These complexes were characterized by Elemental Analysis (C, H and N), Nuclear Magnetic Resonance (NMR) of 1H, 13C {1H}, one-dimensional and two-dimensional, high resolution mass spectrometry, absorption spectroscopy in ultraviolet-visible. The complexes PGG-1, PGG-2, PGG-3 and PGG-4, in water showed transitions n-π*, PGG-3 and PGG-4 exhibited d-d transitions. The GGH-1 and GGH-2 presented n-π* transitions, the complex GGH-3 and GGH-4 exhibited charge transfer bands (MLCT) and d-d transition. The differences found in the absorption spectrum bands in the infrared region (ligand and complex) were a smaller number of bands, inferring the rigidity caused by chelate formation. The copper (II) complexes were characterized by magnetic susceptibility, which are mononuclear. The complexes were tested on bacteria causing citrus canker, which had bacteriostatic activities, evaluated by technique serial microdilution, in which we obtained the Minimum Inhibitory Concentration (MIC), there was inhibited the growth of Xanthomonas citri subsp. citri, in lower concentration in some of the complexes (PGG-1, GGH-1 e PGG-3) compared to the salts used in the synthesis. The tripeptides used did not have bacteriostatic activity, related to the inhibition activity of bacterial growth to the synthesized complexes.