Syntheses of trisaccharide C-D-E and tetrasaccharide B-C-D-E fragments found in orthosomycins

Diagnostic value of serum miR-25-3p in hypertensive disorders in pregnancy

Hypertensive disorders in pregnancy (HDIP) represent one of the leading causes of maternal and perinatal mortality. microRNA (miR)-25-3p plays roles in HDIP diagnosis. We explored miR-25-3p clinical roles in HDIP. HDIP patients [gestation hypertension (GH), mild preeclampsia (mPE), and severe preeclampsia (sPEz)], and normal pregnant women serving as the control were enrolled. Serum miR-25-3p expression patterns were detected by RT-qPCR. The diagnostic efficacy of miR-25-3p on HDIP was analyzed with a ROC curve. Patients were assigned to the high/low miR-25-3p expression groups according to the median value of miR-25-3p expression. All patients were followed up until delivery, and gestational weeks and pregnancy outcomes were recorded at delivery. The effects of miR-25-3p expression on pregnancy outcomes of GH, mPE, and sPEz patients were analyzed by Kaplan-Meier. miR-25-3p expression in GH, mPE, and sPEz patients was up-regulated. In sPEz patients, systolic and diastolic blood pressure, 24-h urine protein, AST, ALT, GGT, and SCr were increased, and PLT was decreased in the high expression group. High miR-25-3p expression was associated with an increased risk of adverse pregnancy outcomes in PE patients. Collectively, high miR-25-3p expression could aid HDIP diagnosis, and associated with an increased risk of adverse pregnancy outcomes in PE patients.

Synthesis of oligodiaminosaccharides having α-glycoside bonds and their interactions with oligonucleotide duplexes

Syntheses of the novel oligodiaminosaccharides, α-(1→4)-linked-2,6-diamino-2,6-dideoxy-D-glucopyranose oligomers, and their interactions with nucleic acid duplexes DNA-DNA, RNA-RNA, and DNA-RNA are described. Monomers to tetramers of oligodiaminoglucose derivatives having α-glycosyl bonds were successfully synthesized using a chain elongation cycle including glycosylation reactions of a 6-phthalimide glycosyl donor. UV melting experiments for a variety of nucleic acid duplexes in the absence and presence of the oligodiaminosaccharides were performed. The synthesized oligodiaminosaccharides exhibited notable thermodynamic stabilization effects on A-type RNA-RNA and DNA-RNA duplexes, whereas B-type DNA-DNA duplexes were not stabilized by the synthesized oligodiaminosaccharides. Among the oligodiaminosaccharides, the tetramer exhibited the highest ability to stabilize A-type duplexes, and the increase in T(m) values induced by the tetramer were higher than those induced by neomycin B and tobramycin, which are known aminoglycosides having ability to bind and stabilize a variety of RNA molecules. CD spectrometry experiments revealed that the oligodiaminosaccharides caused small structural changes in RNA-RNA duplexes, whereas no appreciable changes were observed in the structure of DNA-DNA duplexes. ITC (isothermal titration calorimetry) experiments demonstrated that the amount of heat generated by the interaction between RNA-RNA duplexes and the tetradiaminosaccharides was approximately double that generated by that between DNA-DNA duplexes and the tetradiaminosaccharides. These results strongly suggested the existence of an A-type nucleic acid specific-binding mode of the oligodiaminosaccharides, which bind to these duplexes and cause small structural changes.

Intramolecular 1,8- versus 1,6-Hydrogen Atom Transfer between Pyranose Units in a (1→4)-Disaccharide Model Promoted by Alkoxyl Radicals. Conformational and Stereochemical Requirements

[reaction: see text] The stereochemical and conformational factors controlling the intramolecular hydrogen atom transfer (HAT) reaction between the two pyranose units in a (1-->4)-disaccharide when promoted by a primary 6-O-yl radical are studied. Models with alpha-d-Glcp-(1-->4)-beta-d-Glcp or alpha-l-Rhamp-(1-->4)-alpha-d-Galp skeletons lead exclusively to the abstraction of H-C-5' and the formation, through a nine-membered transition state, of a 1,3,5-trioxocane ring system in a stable boat-chair conformation. Notwithstanding, derivatives of alpha-l-Rhamp-(1-->4)-alpha-d-Glcp abstract exclusively H-C-1' through a seven-membered transition state and therefore lead to an interglycosidic spiro ortho ester.

Synthesis and structure of 4-O,6-O-glycosylidene glycosides

Interglycosidic spiro ortho esters (9-20) were efficiently prepared from methyl 2,6-di-O-benzylgluco- or galactopyranoside and various sugar lactones in the presence of methoxytrimethylsilane and a catalytic amount of trimethylsilyl triflate. All of the prepared sugar ortho esters possess perhydrospiro[2H-pyran-2,2'-pyrano[3,2-d][1,3]dioxin] ring systems commonly in their molecules and, remarkably, were afforded as single isomers. The configurations of the spiro centers in their molecules were determined or estimated by X-ray single crystallographic analysis and molecular modeling studies. By comparing the conformations of prepared ortho esters, we revealed that the difference in the stability between two possible isomers was principally caused from that between the spiro ring systems in their molecules in each case.

Synthesis of a terminal A-B-C disaccharide fragment of flambamycin, curamycin, and avilamycin

Methyl 2,6-dideoxy-4-O-[2,6-dideoxy-4-O-(3,5-dichloro-4-hydroxy-2-methoxy-6- methylbenzoyl)-beta-D-arabino-hexopyranosyl]-alpha-D-arabino-he xopyranoside (25) corresponds to an A-B-C disaccharide subunit of the title antibiotics. It was synthesized from suitably protected monosaccharide and aromatic precursors. The readily available 4,6-O-benzylidene-1,2-O-(R)-propylidene-alpha-D-glucopyranose was converted in six steps into 2-O-acetyl-4-O-benzoyl-3-O-benzyl-6-deoxy-alpha-D-glucopyranosyl bromide, which was condensed with methyl 3-O-benzyl-2,6-dideoxy-alpha-D-arabino-hexopyranoside in the presence of mercury(II) cyanide. Methyl 4-O-(2-O-acetyl-4-O-benzoyl-3-O-benzyl-6-deoxy-beta- D-glucopyranosyl)-3-O-benzyl-2,6-dideoxy-alpha-D-arabino-hexopyranosi de was converted either into methyl 2,6-dideoxy-4-O-(6-deoxy-beta-D- glucopyranosyl)-alpha-D-arabino-hexopyranoside by removal of the protective groups or into methyl 3-O-benzyl-4-O-(3-O-benzyl-2,6-dideoxy-beta-D-arabino-hexopyranosyl)-2,6 - dideoxy-alpha-D-arabino-hexopyranoside (22) by selective deacetylation, Barton deoxygenation, and Zemplén debenzoylation. Disaccharide 22 was deprotonated with butyllithium and treated with 4-benzyloxy-3,5-dichloro-2-methoxy-6-methylbenzoyl chloride to give the title compound 25 after hydrogenolysis.