- COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
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Page/Page column 45-49; 58
(2010/12/31)
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- Enantioselective ester hydrolysis catalyzed by imprinted polymers. 2
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Highly cross-linked network polymers prepared by molecular imprinting catalyzed enantioselectively the hydrolysis of N-tert-butoxycarbonyl phenylalanine-p-nitrophenyl ester (BOCPheONP). The templates were designed to allow incorporation of the key catalytic elements, found in the proteolytic enzyme chymotrypsin, into the polymer active sites. Three model systems were evaluated. These were constructed from a chiral phosphonate analogue of phenylalanine (series A, C) or L-phenylalanine (series B) attached by a labile ester linkage to an imidazole-containing vinyl monomer. Free radical copolymerization of the template with methacrylic acid (MAA) and ethylene glycol dimethacrylate (EDMA) gave a highly cross-linked network polymer. The templates could be liberated from the polymers by hydrolysis, giving catalytically active sites envisaged to contain an enantioselective binding site, a site complementary to a transition state like structure (series A, C), and a hydroxyl, imidazole, and carboxylic acid group at hydrogen bond distance. As predicted, the enantiomer of BOCPheONP complementary to the configuration of the template was preferentially hydrolyzed with D-selectivity for the series A polymers (kD/kL= 1.9) and L-selectivity for the series B polymers (kL/kD = 1.2). The maximum rate enhancement, when compared with a control polymer, prepared using a benzoyl-substituted imidazole monomer as template, was 2.5, and comparing with the imidazole monomer in solution, a maximum rate enhancement of 10 was observed. The catalytic activity was higher for polymers subjected to the nucleophilic treatment. This was explained by a higher site density and flexibility of the polymer matrix caused by this treatment. In a comparison of template rebinding to polymers imprinted with a template containing either a carboxylate (planar ground state structure) or a phosphonate (tetrahedral transition state like structure) functionality, it was observed that imprinted polymers are able to discriminate between a transition state like and a ground state structure for transesterification. However the influence of transition state stabilization on the observed rate enhancements remains obscure. Only at acidic pH's was catalysis observed, whereas at basic pH's the polymers inhibit the reaction. At a later stage, the catalytic activity of the polymers for nonactivated D- and L-phenylalanine ethyl esters was investigated. A rate enhancement of up to 3 was observed when compared to the blank. Most important, however, the polymers imprinted with a D template preferentially hydrolyzed the D-ethyl ester and exhibited saturation kinetics.
- Sellergren,Karmalkar,Shea
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p. 4009 - 4027
(2007/10/03)
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- Synthesis and in vitro pharmacology of a series of new chiral histamine H3-receptor ligands: 2-(R and S)-amino-3-(1H-imidazol-4(5)-yl)propyl ether derivatives
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To investigate stereospecificity and the mechanism of activation of the histamine H3-receptor, a series of 2-(R and S)-amino-3-(1H-imidazol-4(5)- yl)propyl ether derivatives were synthesized. In these compounds, the structures of the well-known antagonist iodoproxyfan and the full agonists R- or S-(α)-methylhistamine were combined in one molecule. The obtained 'hybrid' molecules were tested for H3-receptor affinity on rat cerebral cortex. Some selected compounds were further screened for H3-receptor functional activity with GTPγ[35S] autoradiography studies using rat brain tissue sections. The affinity of all the synthesized compounds (-log K(i) = 5.9-7.9) was lower than that found for iodoproxyfan or two of its analogues; however, the compounds showed stereospecificity. The S-configuration of the series of 2-amino-3-(1H-imidazol-4(5)-yl)propyl ether derivatives, which resembles the stereochemistry of R-(α)-methylhistamine, was more favorable. Incorporation of an amino group in the propyl chain of iodoproxyfan and analogues did not alter the antagonistic behavior for compounds with an aromatic side chain. However, when also the aromatic moiety was replaced by a cyclohexyl group, the compounds behaved as agonists. This indicates that an interaction between the side chain amino group and the H3-receptor protein is involved in H3-receptor activation. The 2-(S)-amino-3-(1H-imidazol-4(5)- yl)propyl cyclohexylmethyl ether (23) has H3-receptor agonistic properties with high affinity for the histamine H3-receptor (-log K(i) = 7.9 ± 0.2) and might serve as a useful tool for further studies concerning drug design and receptor-ligand interactions.
- Kovalainen, Jari T.,Christiaans, Johannes A. M.,Kotisaari, Sanna,Laitinen, Jarmo T.,M?nnist?, Pekka T.,Tuomisto, Leena,Gynther, Jukka
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p. 1193 - 1202
(2007/10/03)
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- Five-membered ring systems with bonded imidazolyl ring substituents
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A class of 5-membered heterocyclic compounds having at least one heteroatom, substituted on the heterocyclic ring by an imidazolyl moiety, are useful in the treatment of psychotic disorders (e.g. schizophrenia and mania); anxiety; alcohol or drug withdrawal or dependence; pain; gastric stasis; gastric dysfunction (such as occurs with dyspepsia, peptic ulcer, reflux oesophagitis and flatulence); migraine, nausea and vomiting; movement disorders; and presenile and senile dementia.
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