Synthesis of antigenic bacterial polysaccharides and their fragments

Conclusions The free trisaccharide-D-mannopyranosyl(1-4)--L-rhamnopyranosyl(1 3)-D-galactopyranose was obtained, which is the repeating unit of the backbone chain of the O-specific polysaccharides ofSalmonella of serological groups A, B, and D₁.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No.1, pp.165–167, January, 1976.     

Synthesis of bacterial antigenic polysaccharides and their fragments 9. Synthesis of the trisaccharide repeating unit of the O-specific polysaccharide of Salmonella newington with a radioactive label in the mannose residue

Conclusions The total acetate of -D-mannopyranosyl-2-³H-(1 4)--L-rhamnopyranosyl-(1 3)-D-galactopyranose] has been synthesized by introducing the radioactive label into the mannose residue during NaBH₄-³H reduction of 4-0-(3,4,6-tri-O-benzyl--D-arabinohexylosopyranosyl)-2,3-O-isopropylidene--benzyl-L-rhamnoside.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2124–2128, September, 1978.The authors wish to thank N. É. Bairamova, M. V. Ovchinnikov, and V. I. Torgov for supplying the starting materials and for valuable consultations.     

Synthesis of bacterial antigenic polysaccharides and their fragments V. Use of 1,2-o-isopropylidene-4,6-O-ethylidene-α-D-galactopyranose for the synthesis of oligosaccharides with 3-o-substituted galactopyranose residue

Conclusions Trisaccharide-D-glucopyranosyl-(14)--L-rhamnopyranosyl-(1 3)-D-galactose was synthesized by using, 2-O-isopropylidene-4,6-O-ethylidene--D-galactopyranose for producing 1 3-rhamnosylgalactose, linkage.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1609–1613, July, 1977.     

Bacterial antigenic polysaccharides

Conclusions Based on the data of selective cleavage, methylation, and oxidation with CrO₃ it was shown that the repeating unit of the polysaccharide chain of the liposaccharide from type 6Sh. dysenteriae is the trisaccharide-D-N-acetylgalactosaminyl-(1–3)--D-galactopyranosyl-(1–6)--D-glucopyranose, to the galactose residue of which is attached an unindentified acid component in the 4 position.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2302–2308, October, 1975.The authors express their gratitude to G. V. Vikha for graciously supplying the-hexosaminidase and to B. M. Zolotarev for taking the mass spectra.     

Synthesis of bacterial antigenic polysaccharides and their fragments 6. Improved synthesis of β-D-mannopyranosyl-(1→4)-α-1-rhamnopyranosyl-(1→3)-D-galactose- the repeating unit of the specific polysaccharide of Salmonella Newington

Conclusions We have synthesized the trisaccharide-D-mannopyranosyl-(1 4)--L-rhamnopyranosyl-(1 3)-D-galactose using 1,2-O-isopropylidene-4,6-O-ethylidene--D-galactopyranose to form the 1 3 rhamnosylgalactose linkage.Part 5 [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2578–2581, November, 1977.     

Synthesis of C-terminal fragments of bombesin and their analogues

With the aim of structural-functional studies in the bombesin series, a number of bombesin fragments and analogues have been synthesized. The synthesis was performed by the carbodiimide method and by the activated-ester method. Fragments with the sequences 7–14, 8–14, and 9–14 were obtained by 4+4, 3+4, and 2+4 schemes and a pentapeptide with the sequence 9–13 by a 3 + 2 scheme. Acetylation of the octapeptide BN(7–14) was carried out by the action of acetic anhydride in pyridine. Analogues of the C-terminal nonapeptide of bombesin [DPhe⁷]BN(6–14) and [Pro⁶, Gly⁷, DAla¹¹]BN(6–14) were synthesized by fragment condensation using the 5 + 4 scheme. The individuality of the compounds obtained was confirmed by their chromatographic behavior on plates coated with silica gel, and by the results of amino acid analysis, high-voltage electrophoresis, and high-performance liquid chromatography, and their structures were confirmed by the results of high-resolution¹H NMR spectroscopy (360 MHz). In experiments on rabbits, in a dose of 1 µg with central administration the full hypothermic effect of bombesin was shown by the preparation [AcGln⁷]BN(7–14), while the preparation [DPhe⁷]BN(6–14) and [Pro⁶,Gly⁷,DAla¹¹]BN(6–14) possessed only a slight effect (～1% of the activity of bombesin).     

Synthesis of C-terminal fragments of bombesin and their analogues

With the aim of structural-functional studies in the bombesin series, a number of bombesin fragments and analogues have been synthesized. The synthesis was performed by the carbodiimide method and by the activated-ester method. Fragments with the sequences 7–14, 8–14, and 9–14 were obtained by 4+4, 3+4, and 2+4 schemes and a pentapeptide with the sequence 9–13 by a 3 + 2 scheme. Acetylation of the octapeptide BN(7–14) was carried out by the action of acetic anhydride in pyridine. Analogues of the C-terminal nonapeptide of bombesin [DPhe⁷]BN(6–14) and [Pro⁶, Gly⁷, DAla¹¹]BN(6–14) were synthesized by fragment condensation using the 5 + 4 scheme. The individuality of the compounds obtained was confirmed by their chromatographic behavior on plates coated with silica gel, and by the results of amino acid analysis, high-voltage electrophoresis, and high-performance liquid chromatography, and their structures were confirmed by the results of high-resolution¹H NMR spectroscopy (360 MHz). In experiments on rabbits, in a dose of 1 µg with central administration the full hypothermic effect of bombesin was shown by the preparation [AcGln⁷]BN(7–14), while the preparation [DPhe⁷]BN(6–14) and [Pro⁶,Gly⁷,DAla¹¹]BN(6–14) possessed only a slight effect (1% of the activity of bombesin).Leningrad State University. Institute of Organic Synthesis, Latvian SSR Academy of Sciences, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 554–564, July–August, 1989.     

Synthesis of peptidoglycan fragments and evaluation of their biological activity

The peptidoglycan (PG) bacterial cell wall glycoconjugate has been well known as a strong immunopotentiator. Partial structures of PG were chemically synthesized for elucidation of precise biological activities. Effective construction of distinct repeating glycans of PG was accomplished by the coupling of a key disaccharide glucosaminyl-beta(1-4)-muramic acid unit. Stereoselective glycosylation of disaccharide units was achieved by neighboring group participation of the N-Troc (Troc = 2,2,2-trichloroethoxycarbonyl) group and appropriate reactivity of N-Troc-glucosaminyl trichloroacetimidate. By using an efficient synthetic strategy, mono-, di-, tetra- and octasaccharide fragments of PG were synthesized in high yields. The biological activity of synthetic fragments of PG was evaluated by induction of tumor necrosis factor-alpha (TNF-alpha) from human monocytes, and toll-like receptor 2 (TLR2) and Nod2 dependencies by using transfected HEK293 cells, respectively. Here we reveal that TLR2 was not stimulated by the series of synthetic PG partial structures, whereas Nod2 recognizes the partial structures containing the MDP moiety.     

Synthesis and investigation of polyethylene blends with natural polysaccharides and their derivatives

Powder blends of LDPE with cellulose, ethyl cellulose, starch, chitin, and chitosan have been prepared under shear deformation in a rotor disperser at different initial-component ratios. The composition of powder fractions is identical to the original composition of the blends. The studied polymer blends demonstrate high mechanical characteristics. X-ray diffraction analysis and DSC studies show that the blending of LDPE with polysaccharides under shear deformations results in changes in the polymer structure and leads to a decrease of their degree of crystallinity. The maximum intensity of mold fungi growth is observed in starch-LDPE (50: 50, wt/wt) and chitin-LDPE (50: 50, wt/wt) blends.     

Synthesis of substituted hydroxymethylene diphosphonic acids and their derivatives containing unsaturated fragments

Russian Journal of General Chemistry -     

Synthesis of hybrid photochromes containing fulgimide and salicylidenaniline fragments and study of their properties

Fulgimide salicylidenaniline derivatives were synthesized and studied in solutions and solid-phase films. It was found that the compounds obtained exhibit photochromic properties in different aggregate states. Comparative studies showed that the nature of substituents in the aldehyde moiety of the fulgimide azomethine fragments has little effect on the photochromic properties of the compounds obtained.     

Synthetic fragments of antigenic lipophosphoglycans from Leishmania major and Leishmania mexicana and their use for characterisation of the Leishmania elongating alpha-D-mannopyranosylphosphate transferase

The phosphorylated branched heptasaccharides 7 and 8, the octasaccharide 9 and the phosphorylated trisaccharides 5 and 6, which are fragments of the phosphoglycan portion of the surface lipophosphoglycans from Leishmania mexicana (5) or L. major (6-9), were synthesised by using the glycosyl hydrogenphosphonate method for the preparation of phosphodiester bridges. The compounds were tested as acceptor substrates/putative inhibitors for the Leishmania elongating alpha-D-mannosylphosphate transferase.