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Abstract. Four coordination compounds of iron(III) with ligands based on hydrazine and sulfadiazine: [Fe(dig) 2 -2,6-diacetylpyridine bis(isonicotinoylhydrazone) were synthesized. The spectroscopic and structure characterisation, as well as their biological properties, are presented. All tested coordination compounds, caused an inhibitory effect on the biosynthesis of hydrolases of the producer Aspergillus niger CNMN FD-10. The effect increased with the raise of the concentration from 5 mg/L to 15 mg/L. The complexes largely inhibited cellobiohydrolase and less-β-glucosidase. The inhibitory effect of the coordination compounds was quite similar in the case of endoglucanase and xylanase. Compound I, containing both chloride ions and dig, demonstrated a stronger inhibitory effect, while compound III, containing NO 3 -ions, showed the weakest inhibitory action.Keywords: iron complexes, nitrogen-containing ligands, structure, biological properties. IntroductionIn the modern microbiology, investigation of the effects of external factors on the physiology of microorganisms remains an actual issue. Such studies allow solving the practical problems and implementation of the new technologies in biology and medicine.The literature, in the last decades, denotes high physiological activity of the coordination compounds of transition metals on biological objects, including microorganisms [1][2][3][4][5][6][7][8][9][10][11][12][13]. Some authors note a signifi cant role of these compounds in the directed synthesis of biologically active substances from microalgae and cyanobacteria, fi lamentous fungi and yeast [1][2][3][4][5][6][7][8][9][10]12].Studies of the effects of coordination compounds on biosynthesis of extracellular hydrolases in fi lamentous fungi have been previously carried out [3][4][5][6][7]14]. It was established that these effects depend both on the properties of compounds (chemical composition, molecular structure, nature of the ligand and coordinated metal atom) and genus and species of the micromycetes strains, and specifi city of the synthesized enzymes [3][4][5][6][7]14]. Some coordination compounds exhibit a selective action on the components of the synthesized enzyme complex. Thus, by adding the molybdenum complex with valine -MoO 2 (acac) 2 Val (acac=acetylacetone, Val=valine) into the nutrient medium, the biosynthesis of β-glucosidase in micromycete Penicillium expansum CNMN FD 5C -producer of cellulases was enhanced by 69.4%, while the level of endoglucanase and cellobiohydrolase was not modifi ed. Study of the infl uence of (NH 4 ) 2 VO 2 Gly (Gly=glycine) on biosynthesis of cellulases of the same strain showed that the dioxovanadium complex increased the activity of all components of cellulase complex by 17.6-40.3% [14].The targeted application of the coordination compounds of 3d-elements as regulators of the microbial synthesis of bioactive substances requires accumulation of factual material on the nature of their infl uence on all phases of the development of microorganisms and also identifi ca...

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