Pharmacological science possesses a significant number of compounds with antibiotic activity. By now the chemical structures have been identified and their properties have been described for the great number; many of them found practical use. But the main stimulus for the further new antibiotic compounds search is the acquired resistance of pathogenic organisms. Our previous investigations were devoted to antibiotic activity of Aspergillus niveus that is known as a producer of ferment preparations with wide activity spectrum. Aim. This investigation became the follow-up of our previous studies and its main task was to isolate, purify and obtain biologically active metabolite(s) from A. niveus 2411 strain in crystalline form, and to study its (their) physicochemical properties and biological activity. Methods. Biologically active metabolites were obtained by extraction, two-step column chromatography and recrystallization methods. The obtained substances were characterized by physical-chemical and microbiological methods. Results. Two substances in crystalline form with different spectrum of antibiotic activity against indicator test-cultures were obtained. The substance AN4 showed antibacterial, antifungal, and phytotoxic activities, while AN7 showed only antibacterial activity. Neither of obtained compounds showed dermatocidal or toxigenic activity in rabbit skin test. Obtained spectral characteristics of substances suggest that AN4 and AN7 substances are similar and belong to compounds with cyclic structures, have double linkage, methyl, aromatic, and carboxyl groups. Conclusions. Obtained data showed that antibiotic activity of A. niveus 2411 depend on the complex of biologically active metabolites with different biological and physicochemical properties. Two compounds AN4 and AN7 were isolated and purified from the fungal cultural filtrate of A. niveus 2411. The data of IR and UV spectra of these compounds and their profiles of biological activity don’t have significant differences with those of citrinin – a metabolite of A. niveus with antibiotic properties. However, based on the results obtained and comparisons with the data of other authors on metabolites of A. niveus, we suggest that the substances we isolated may be derivatives of citrinin.

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