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The synthesis of several novel 11-substituted prostaglandins has been achieved from PGA2 methyl ester from the marine coral . The configuration of the substituents at position 11 is based on the nuclear magnetic resonance properties.  相似文献   

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This article describes the preparation of (±)-11-deoxy-15-ethynyl prostaglandins ( & ). The key step involves a conjugate addition of the substituted 1-lithio-1-oct-1-ene ( ) to the cyclopentenone ( & ) to furnish 11-deoxy-prostaglandin skeleton in a simple fashion. Of particular interest in this synthesis is the preparation of alkyl side chain ( ) which was achieved in an efficient three-step synthesis starting from the readily available β-iodo vinyl ketone ( ).  相似文献   

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An overview of chiral reagents that are used to assign the absolute configuration of particular classes of compounds using NMR spectroscopy is presented. The use of chiral derivatizing agents, chiral solvating agents, metal complexes, and liquid crystals is described. Chirality, 2011. © 2010 Wiley‐Liss, Inc.  相似文献   

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The relationship of prothrombin structure to function with respect to gamma-carboxyglutamic acid (Gla) residues can be effectively evaluated by characterizing the behavior of prothrombin isomers differing in Gla content. In addition to the isolation of a whole spectrum of Gla-deficient, 0- to 9-Gla isomers from dicoumarol-treated plasma, prothrombin isomers containing 11 (10.90) and 9 (8.85) Gla residues have now been isolated from normal bovine plasma. The isomers were isolated by barium citrate adsorption, elution, and finally by heparin-agarose, DEAE-cellulose, and immuno-affinity chromatographies. Each of the purified isomers showed a single component by agar gel and sodium dodecyl sulfate - polyacrylamide gel electrophoresis. By agar gel electrophoresis, the 11-Gla prothrombin isomer moved the fastest, followed by the 10-, and lastly the 9-Gla isomer, independent of Ca2+. The corresponding 9-, 10-, and 11-Gla prothrombin fragments 1 exhibited similar migration tendencies. By gel electrofocusing, 11- and 9-Gla fragments 1, respectively, focused anodal and cathodal to 10-Gla fragment 1. The Ca2+-induced decrease in the intrinsic fluorescence in 11-, 10-, and 9-Gla fragments 1 was 48, 40, and 45%, respectively. This metal-induced structural change did not correlate with the functional, thrombin-generating property of the isomers, as the 9-Gla variant exhibited 75%, and the 11-Gla 110-115%, of normal coagulant activity.  相似文献   

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Four methods of the synthesis of model glycosides with 11-deoxyprostaglandin E1 and a connecting polymethylene chain as the aglycone are compared. Interaction of potassium salt of prostaglandin PG with omega-iodoalkylglycosides is the most promising approach.  相似文献   

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A series of 11-deoxy prostaglandin derivatives and some naturally occurring prostaglandins have been investigated in the anaesthetized artificially respired guinea-pig for their effect on blood pressure, bronchial resistance (overflow pressure at constant volume), tracheal segment pressure, and on intestinal and uterine smooth muscle. The compounds were administered intravenously. Prostaglandins E1, E2 and F produced responses that were qualitatively similar to those in the literature. Prostaglandin A2 (100 μg) was a bronchoconstrictor, although it decreased tracheal segment pressure and blood pressure. Prostaglandin B2 (100 μg) caused double elevations in blood pressure, tracheal segment pressure and bronchial resistance. The intensity of bronchoconstriction produced by PGB2 was of the same order as with PGF. A number of structure-activity relationships were found. 11-Deoxygenation lowered the biological activity of the natural prostaglandins PGE1 and PGF. The vasodepressor and bronchodilator responses of 11-deoxy PGE1 were converted to vasopressor and bronchoconstrictor by epimerisation at C-15. Introduction of a methyl group at C-15 of 11-deoxy PGF both increased and prolonged vasopressor and bronchoconstrictor activity. At C-9 both the keto and β-hydroxy group imparted vasodepressor and bronchodilator activity, while the α-hydroxy led to vasopressor and bronchoconstrictor activity. Extension of the omega sidechain by two methylene groups radically reduced the activity of 11-deoxy PGF and its derivatives.These experiments indicate that steric differences in the prostaglandin structures studied can result in diametrically opposed profiles of biological activity. Further, small variations in the prostaglandin molecule can lead to differences in potency and/or profile of activity in the guinea-pig.  相似文献   

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Macropodumines B and C (1, 2) are fused pentacyclic alkaloids previously isolated from the Chinese medicinal plant Daphniphyllum macropodum. Macropodumine B (1) possesses an amazing structural feature of a cyclopentadienyl carbanion, stabilized as a zwitterion by an internal iminium cation, which was confirmed by X-ray diffraction analysis. On the basis of the X-ray geometry, the absolute configuration of 1 was determined by employing the solid-state CD/TDDFT approach. The absolute configuration of 2 was instead determined by using TDDFT CD calculations on DFT-optimized geometries, in comparison with CD spectra recorded in solution.  相似文献   

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Hydroxyl-containing 11-deoxyprostaglandin E1 esters were synthesised by using the methods of mixed anhydrides and nucleophilic displacement.  相似文献   

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Assignment of absolute configuration to a recently developed chiral selector useful in the separation of the underivatized enantiomers of naproxen and other nonsteroidal anti-inflammatory drugs (NSAIDs) is described. Circular dichroism, 1H NMR, and X-ray diffraction have been used to confirm the original assignment which was based solely upon elution orders from HPLC chiral stationary phases. All of these techniques agree in the assignment of the (S,S) absolute configuration to the enantiomer of the chiral selector which associates preferentially with (S)-naproxen. © 1994 Wiley-Liss, Inc.  相似文献   

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Background

Hearing ability is essential for normal speech development, however the precise mechanisms linking auditory input and the improvement of speaking ability remain poorly understood. Auditory feedback during speech production is believed to play a critical role by providing the nervous system with information about speech outcomes that is used to learn and subsequently fine-tune speech motor output. Surprisingly, few studies have directly investigated such auditory-motor learning in the speech production of typically developing children.

Methodology/Principal Findings

In the present study, we manipulated auditory feedback during speech production in a group of 9–11-year old children, as well as in adults. Following a period of speech practice under conditions of altered auditory feedback, compensatory changes in speech production and perception were examined. Consistent with prior studies, the adults exhibited compensatory changes in both their speech motor output and their perceptual representations of speech sound categories. The children exhibited compensatory changes in the motor domain, with a change in speech output that was similar in magnitude to that of the adults, however the children showed no reliable compensatory effect on their perceptual representations.

Conclusions

The results indicate that 9–11-year-old children, whose speech motor and perceptual abilities are still not fully developed, are nonetheless capable of auditory-feedback-based sensorimotor adaptation, supporting a role for such learning processes in speech motor development. Auditory feedback may play a more limited role, however, in the fine-tuning of children''s perceptual representations of speech sound categories.  相似文献   

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In this study, we report theoretical specific rotation values for a series of cis-/trans-alkylated-[5]-ladderanes and cis-/trans-methylated-[n]-ladderanes. Using time-dependent density functional response theory optical rotation calculations, we can assign (+) and (-) optical rotation signs to trans-(S)-alkyl-[5]-ladderane and trans-(R)-alkyl-[5]-ladderane configurations, respectively. In order to qualitatively validate our absolute configuration predictions, we computed optical rotation values at three different levels of theory--B3LYP, RI-BP86, and Hartree-Fock--using the aug-cc-pVDZ basis set. We observe a novel rung-parity-controlled oscillatory optical rotatory phenomenon in our computations, which, to the best of our knowledge, has never been reported or observed before. Furthermore, this preliminary analysis of optical rotation properties in this class of compounds should facilitate the correct absolute stereochemical assignment of natural and synthetic ladderanes, such as the trans-isomer of pentacyclic C(20)-fatty acid methyl ester (pentacycloanammoxic methyl ester), without the need for derivatization, in particular for cases where NMR or X-ray crystal structures are not readily available.  相似文献   

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Vanadium in the 4+ (vanadyl-ion) and 5+ (vanadate-ion) oxidation state stimulates furosemide-sensitive electrogenic Cl- secretion in isolated epithelia of rabbit descending colon. This effect is associated with an increased release of prostaglandin E2 from the tissue. Inhibitors of phospholipase A2 or cyclooxygenase abolish both vanadium-induced release of prostaglandin E2 and Cl- secretion. Neuronal mechanisms are not likely to be involved, as tetrodotoxin does not affect the vanadate induced Cl- secretion. Although vanadate is known to inhibit Na+,K(+)-ATPase activity, no inhibition of active Na+ transport was observed in intact colonic epithelia suggesting a rapid intracellular reduction of vanadate ions to vanadyl ions which have no inhibitory effect on the Na+,K(+)-ATPase. The present findings therefore indicate that vanadate stimulated colonic Cl- secretion involves intracellular conversion of vanadate to vanadyl and release of prostaglandin E2.  相似文献   

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Yang Y  Kayser MM  Hooper D 《Chirality》2005,17(3):131-134
The absolute configurations of several 3-hydroxy beta-lactams were assigned by the NMR "mix and shake" methodology developed by Riguera and co-workers. The results from the NMR study correlated perfectly with the absolute configurations obtained from X-ray crystallographic structure analyses and chiral-phase HPLC data.  相似文献   

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