Biomedical subjects
Publications and source records attributed to V I Shvets.
The current state and prospects of using the liposomal forms of anthracyclinic antibiotics, fluoroucil agents, and platinum compounds are discussed as potential drugs for chemotherapy of tumors. Comparative studies of standard and liposomal forms of the above groups of compounds were made to determine their therapeutical effects.
Incorporation of 9-cis-13-demethylretinal into bacterioopsin was shown to form the covalent purple complex. This result was predicted by our hypothesis about the structure of the BR chromophore cavity (Mol. Biologiya 29:1398-1407 (1995) (in Russian)). It supports the hypothesis and eliminates the main objection known from the literature.
The results and problems of synthetic studies of natural inositol containing glycophospholipids as well as their biologically active fragments and structural analogs are reviewed.
A method for betulinic acid synthesis from betulin was developed. Betulin was oxidized with chromium oxide (VI) into betulonic acid, which was reduced with sodium borohydride to yield a mixture of 3-hydroxy epimers containing 85% of the natural beta-epimer. Studying changes in light scattering by dispersions of liposomes with different contents of betulinic acid revealed that up to 10 mol % of this compound may be entrapped in liposomes. The dependence of the efficiency of the betulinic acid entrapment on liposome composition was studied. The presence of polyvinylpyrrolidone or Proxanol increased the resistance of betulinic acid-containing liposomes to aggregation. These polymers solubilized betulinic acid with the same efficiency as liposomes.
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Oxidation of egg phosphatidylcholine and catechols (L-3,4-dihydroxyphenylalanine or dopamine) in liposome dispersions was studied. These catechols, encapsulated in liposomes, were shown to decrease the rate of phosphatidylcholine oxidation by factors of 4.9 and 2.6, respectively, at storage in darkness at 4 degrees C. After 40 min of Fe(II)-ascorbate-induced oxidation, the level of malonaldehyde in such liposomes remained constant, while in the empty liposomes, it increased 3,4-fold. Egg phosphatidylcholine protected catechols encapsulated into liposomes from oxidation, and the rate of this oxidation was shown to be substantially lower than that in micellar solutions under the same conditions. Evidently, this can be due to the barrier function of a lipid bilayer.
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The synthesis of two novel lipophosphonucleoside potential antiviral agents, 2-stearoyl-rac-sphinganine-1-phosphoryl-5'-(3'-deoxy-3'-azido)thymidine and 2-stearoyl-rac-sphinganine-1-phosphoryl-5'-(2',3'-didehydro-2', 3'-dideoxy)thymidine, is reported. The phosphoester linkages between the primary hydroxyl group of rac-ceramide and the 5'-hydroxyl group of the corresponding 3'-deoxythymidine derivative were formed using either the H-phosphonate or the phosphite triester method. The H-phosphonate approach was shown to be the method of choice for the synthesis of ceramide phospho-3'-azidothymidine.
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The total synthesis of 1(3)-O-(rac-1,2-dipalmitoylglycerophospho)-4(6)-O- beta-D-glucopyranosyl-sn-myo-inositol was performed. The major stages of the synthetic route are glycosylation of the substituted myo-inositol derivative by the glycosyl fluoride method and creation of the phosphorus moiety of the target glycolipid by means of the H-phosphonate technique.
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Chiral mannosylinositol containing sphingophospholipid was synthesized from D-erythro ceramide and optically active mannosyl-myo-inositol with the use of phosphite triester coupling procedure. The optical resolution of racemic 3,4,5,6-tetra-O-benzyl-myo-inositol to enantiomers was accomplished via diastereomeric menthoxyacetic esters. Iodonium ion-promoted glycosylation has been used for the preparation of chiral mannosyl-myo-inositol. Bis(diisopropylamino)-2-cyanoethylphosphine has been applied to the introduction of the phosphodiester bond between the primary hydroxyl function of D-erythro-3-O-benzoylceramide and the secondary hydroxyl group of optically active and partially benzylated 1-O-(2-O-alpha-D-mannopyranosyl)- D-myo-inositol.
A new method for the preparative isolation of individual amino acids on a milligram scale based on reversed-phase high-performance liquid chromatography (RP-HPLC) after pre-column derivatization with carbobenzoxychloride (Z-Cl) has been developed. The chromatographic procedure was tested by the investigation of jack bean urease hydrolysate. The method has been applied to the preparative separation of Z-amino acids (from 10 up to 16) obtained from protein hydrolysates of various sources (green microalgae, blue-green algae, halophilic and methylotrophic microorganisms) and was proved to be reliable by the separation of deuterated amino acids (enrichment 97-99%) from Methylobacillus flagellatum (due to the bioconversion of CD3OD and D2O). Independent of the biological source of the protein, the amino acids were isolated with high recovery (from 68% up to 89%) and chromatographic purity (from 96% up to 99%). The method was also applied for the isolation of phenylalanine and leucine excreted by amino-acid overproducing microorganisms.
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Several retinoids with modified polar group were synthesized. Biological screening using HL-60 promyelocyte leukemia cells showed that the free carboxyl in the retinoid molecules is not the only group responsible for exhibiting the differentiating activity.
The synthesis of optically-active hexadecyl thiophosphoryl-1-D-myo-inositol 11 was accomplished from 2,3-O-(D-1',7',7'-trimethyl[2.2.1]bicyclohept-2'-ylidene)-4,5,6-O- tris(methoxymethyl)-D-myo-inositol 6 or 2,3,4,5,6-O-pentakis(methoxymethyl)-D-myo-inositol 14, using the Arbusov reaction of their dimethyl phosphite derivatives 7 and 15 with N-hexadecyl thiophthalimide 8. This product was a substrate for phosphatidylinositol-specific phospholipase C from Bacillus cereus.
An increase of the mouse fibroblast proliferation by ganglioside GM3 from equine erythrocytes is described. The structure of GM3 has been established on the basis of chemical methods, enzymatic degradation, GC-MS, as well as plasma desorption mass spectrometry and HPLC of 9-anthrylmethyl esters of gangliosides to characterize the long-chain base composition. The oligosaccharide moiety includes an N-glycolylneuraminic acid residue, whereas the main components of the lipid moiety are 20:1 sphingosine and 24:0 fatty acids.
Synthesis of lipophilic derivatives of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) by condensation of the C-terminal amino acid moiety in MDP molecule with phosphatidylethanolamine was carried out. Fluorescent lipophilic derivatives of MDP were synthesized by condensation of MDP with phosphatidylethanolamines labelled in the hydrophobic moiety, e.g. 1-acyl-2-[9(10)-(4-pyrenyl)stearoyl]-sn-glycero-3-phosphoethanolamine and pyrenylphosphatidylethanolamine.