Biomedical subjects
Publications and source records attributed to G B Lokshin.
The results of the structural study of antitumor antibiotic variamycin and its peracetyl derivative by 1H-and 13C-NMR spectroscopy are reported. Structures of carbohydrate chains of the antibiotics molecule are revised. Variamycin is shown to be 2-[beta-cymmarosyl(1-3)-beta-oliosyl (1-3)-beta-olivosyl]-6-[beta-olivosyl (1-3)-beta-olivosyl] chromomycinone.
Stability of azlocillin in aqueous solutions at pH 1.5-12.5 was studied at various temperatures. It was shown that degradation of the antibiotic proceeded as an irreversible first order reaction. Dependence of 1gk on the reverse temperature was described by the Arrhenius equation. The highest levels of azlocillin stability in solutions were observed at pH about 6.0. In solid state azlocillin was stable under the effect of the environmental factors. In the atmosphere of oxygen and carbon dioxide and on exposure to light the quality parameters of the antibiotic powder maintained at the control levels.
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The effect of oxygen and moisture on stability of sodium fusidate was studied. It was shown that inactivation of the antibiotic in the atmosphere of oxygen was due to its oxidation in the preparations with low humidity levels. In the preparations with high humidity levels, the main cause of the antibiotic inactivation was hydrolysis with respect to C-16-O-acetyl group. When sodium fusidate was air stored, the salts of 24, 25-dioxy-and 24, 25-dioxy-11-monoketofusidic acids were identified among the products of its inactivation. The salts of 24,25-dioxy-11-monoketofusidic acid were also prepared by oxidation of fusidic acid with potassium permanganate in a weak alkaline medium. The possibility of using sodium sulfite and metabisulfite as stabilizers for th antibiotic storage was shown.
A possibility of assaying antibiotic sulfates, such as gentamicin, kanamycin, monomycin, neomycin, ristomycin, streptomycin, florimycin and polymyxin M sulfates for sulfate ions by titration with barium chloride in the presence of chlorphosphonaso-III, a metal indicator immediately in the salt solutions or after elimination of the cation by means of ion exchange (sulfocation exchange resins in H+-form) was tested. The procedure was shown to be adequate to the classical weight method.
The basic points in the development of a specialized computer information search system providing ientification of new antibiotics at early stages of their investigation are described. The system of coding the physico-chemical properties of the agents and the spectra of their antimicrobial activity presenting the substance in the information bank is developed. The task of identification is to find in the reference bank according to some specially organized keys such antibiotics which are identical or close by their properties to the substance being identified. Mini-computer of M-6000 type is used as the technical base of the information search system. Preliminary organization of the bank specified by the coding system markedly reduces the requirements to the computer operative memory.
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