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At least 829 records · Page 46Linked to original sources
PubMed2004

Facile synthesis of fused 1,2,4-triazolo[1,5-c]pyrimidine derivatives as human adenosine A3 receptor ligands.

A facile synthetic method for fused triazolopyrimidine derivatives having high affinity and selectivity for human adenosine A(3) receptors is reported. The fused triazolopyrimidine derivatives were easily prepared by one-pot reaction using acylhydrazines and imidates prepared from amine derivatives bearing cyano group and orthoesters in situ. This synthetic method was useful in finding new tricyclic adenosine A(3) receptor antagonists and also in diversifying the substituents at two positions on the fused triazolopyrimidine ring.

Adenosine A3 Receptor Antagonists↗
PubMed2005

Detection and control of aspartimide formation in the synthesis of cyclic peptides.

Extensive two-dimensional NMR analysis was employed to characterize the structural identity of the macrocyclic peptide lactam and the imide analog, a major side reaction product when allyl ester was used to protect the side chain of aspartic acid. A straightforward protocol modification was developed to minimize aspartimide formation during the synthesis of cyclic peptides.

Aspartic Acid↗
PubMed2005

Discovery and development of dimeric podocarpic acid leads as potent agonists of liver X receptor with HDL cholesterol raising activity in mice and hamsters.

Liver X receptors are nuclear receptors that regulate metabolism of cholesterol. They are activated by oxysterols resulting in increased transcription of the ABCA1 gene, promoting cholesterol efflux and HDL formation. We have identified podocarpic acid anhydride as a 1nM agonist of LXRalpha and beta receptors. Functionally this agonist was over 8-10-fold better activator of LXR receptors compared to one of the natural ligands, 22-(R)-hydroxy cholesterol, in HEK-293 cells. An imide analog increased the level of HDL by 26%, decreased LDL by 10.6%, and increased triglyceride by 51% in hamsters. Discovery, synthesis, SAR and details of the activities of dimers have been described.

Abietanes↗
PubMed2005

Design, synthesis, and structure-activity relationship of podocarpic acid amides as liver X receptor agonists for potential treatment of atherosclerosis.

A series of podocarpic acid amides were identified as potent agonists for Liver X receptor alpha and beta subtypes, which are members of a nuclear hormone receptor superfamily that are involved in the regulation of a variety of metabolic pathways including cholesterol metabolism. We recently reported podocarpic acid anhydride and imide dimers as potent LXR agonists. Through parallel organic synthesis, we rapidly identified a series of new podocarpate leads with stable structures exemplified by adamantyl- and phenylcyclohexylmethyl-podocarpic acid amides (14 and 18). Compound 18 exhibited LXRalpha/beta 50/20 nM (binding affinity) and 33.7/35.3-fold receptor inductions. Synthesis, SAR, and biological activities of new podocarpate analogs are discussed.

Abietanes↗
PubMed2005

Angiogenesis inhibitors derived from thalidomide.

5-Hydroxy-2-(2,6-diisopropylphenyl)-1H-isoindole-1,3-dione (5HPP-33: 10), which was obtained during our previous structural development studies on thalidomide, was revealed to possess potent anti-angiogenic activity in a human umbilical vein endothelial cell (HUVEC) assay. Thalidomide (1) and its metabolite, 5-hydroxythalidomide (5-HT: 2), which possesses a hydroxyl group at the position corresponding to that of 5HPP-33, as well as IMiDs (immunomodulatory derivatives of thalidomide: 3 and 5), also showed weak or moderate activity in the same assay.

Angiogenesis Inhibitors↗
PubMed2005

Synthesis and structure-activity relationships of novel poly(ADP-ribose) polymerase-1 inhibitors.

A series of novel pyrrolocarbazoles was synthesized as potential PARP-1 inhibitors. Pyrrolocarbazole 1 was identified as a potent PARP-1 inhibitor (IC50 = 36 nM) from our internal database. Synthesis of analogs around this template with the aid of modeling studies led to the identification of the truncated imide 14. Compound 14 (IC50 = 40 nM), with deleted B-ring, was found to be an equipotent PARP-1 inhibitor.

Carbazoles↗
PubMed2006

Synthesis and G-quadruplex stabilizing properties of a series of oxazole-containing macrocycles.

The synthesis of 24-membered macrocycles containing four, six, and seven oxazole moieties is described. Selected compounds were evaluated for their ability to specifically bind and stabilize G-quadruplex DNA and for cytotoxic activity. An unexpected oxidative cleavage reaction afforded a macrocyclic imide that was also evaluated for G-quadruplex stabilizing and cytotoxic activity.

DNA↗
PubMed2004

Synthesis of a hexasaccharide fragment of the O-deacetylated GXM of C. neoformans serotype B.

beta-D-Xylp-(1-->4)-alpha-D-Manp-(1-->3)-[beta-D-Xylp-(1-->2)]-alpha-D-Manp-(1-->3)-[beta-D-Xylp-(1-->2)]-alpha-D-Manp, the fragment of the exopolysaccharide from Cryptococcus neoformans serovar B, was synthesized as its methyl glycoside. Thus, acetylation of allyl 3-O-benzoyl-4,6-O-benzylidene-alpha-D-mannopyranoside (1) followed by debenzylidenation and selective 6-O-benzoylation afforded allyl 2-O-acetyl-3,6-di-O-benzoyl-alpha-D-mannopyranoside (4). Glycosylation of 4 with 2,3,4-tri-O-benzoyl-D-xylopyranosyl trichloroacetimidate (5) furnished the beta-(1-->4)-linked disaccharide 6. Deallylation followed by trichloroacetimidate formation gave the disaccharide donor 8, and subsequent coupling with allyl 2,3,4-tri-O-benzoyl-beta-D-xylopyranosyl-(1-->2)-4,6-di-O-benzoyl-alpha-D-mannopyranoside (9), produced the tetrasaccharide 10. Reiteration of deallylation and trichloroacetimidate formation from 10 yielded the tetrasaccharide donor 12. The downstream disaccharide acceptor 18 was obtained by condensation of 5 with methyl 3-O-acetyl-4,6-O-benzylidene-alpha-D-mannopyranoside, followed by debenzylidenation, benzoylation, and selective 3-O-deacetylation. Coupling of 18 with 12 afforded the hexasaccharide 19, and subsequent deprotection gave the hexasaccharide glycoside 20. Selective 2"-O-deacetylation of 19 gave the hexasaccharide acceptor 21. Condensation of 21 with glucopyranosyluronate imidate 22 did not produce the expected heptasaccharide glycoside; instead, a transacetylation product 19 was obtained. Meanwhile, there was no reaction between 21 and the bromide donor 23.

Acetamides↗
PubMed2005

Synthesis of alpha-series ganglioside GM1alpha containing C20-sphingosine.

A synthesis of alpha-series ganglioside GM1alpha (III(6)Neu5AcGgOse4Cer) containing C20-sphingosine(d20:1) is described. Glycosylation of 2-(trimethylsilyl)ethyl 2,3,6-tri-O-benzyl-beta-D-galactopyranosyl-(1-->4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside with the glucosamine donor ethyl 3-O-acetyl-2-deoxy-4,6-O-[(4-methoxyphenyl)methylene]-2-phthalimido-1-thio-beta-D-glucopyranoside furnished a beta-(1-->4)-linked trisaccharide. Reductive cleavage of the p-methoxybenzylidene group followed by intramolecular inversion of its triflate afforded the desired trisaccharide, which was transformed into a trisaccharide acceptor via removal of the phthaloyl and O-acetyl groups followed by N-acetylation. A tetrasaccharide acceptor was obtained by glycosylation of the trisaccharide acceptor with dodecyl 2,3,4,6-tetra-O-benzoyl-1-thio-beta-D-galactopyranoside, followed by removal of the p-methoxybenzyl group. Coupling of the tetrasaccharide acceptor with ethyl (methyl 4,7,8,9-tetra-O-acetyl-3,5-dideoxy-1-thio-5-trichloroacetamido-D-glycero-D-galacto-2-nonulopyranosid)onate and subsequent radical reduction gave the desired GM1alpha saccharide derivative, which was coupled with (2S,3R,4E)-2-azido-3-O-benzoyl-4-eicosene-1,3-diol after conversion into the imidate.

Carbohydrate Sequence↗
PubMed2005

Synthesis of a heptasaccharide fragment of the O-deacetylated GXM of C. neoformans serotype C.

Beta-D-Xylp-(1-->2)-alpha-D-Manp-(1-->3)-[beta-D-Xylp-(1-->2)][beta-D-Xylp-(1-->4)]-alpha-D-Manp-(1-->3)-[beta-D-Xylp-(1-->4)]-alpha-D-Manp, the fragment of the exopolysaccharide from Cryptococcus neoformans serovar C, was synthesized as its methyl glycoside. Thus, chloroacetylation of allyl 3-O-acetyl-4,6-O-benzylidene-alpha-D-mannopyranoside (1) followed by debenzylidenation and selective 6-O-benzoylation afforded allyl 2-O-chloroacetyl-3-O-acetyl-6-O-benzoyl-alpha-D-mannopyranoside (4). Glycosylation of 4 with 2,3,4-tri-O-benzoyl-D-xylopyranosyl trichloroacetimidate (5) furnished the beta-(1-->4)-linked disaccharide 6. Dechloroacetylation gave the disaccharide acceptor 7 and subsequent coupling with 5 produced the trisaccharide 8. Deacetylation of 8 gave the trisaccharide acceptor 9 and subsequent coupling with a disaccharide 10 produced the pentasaccharide 11. Reiteration of deallylation and trichloroacetimidate formation from 11 yielded the pentasaccharide donor 12. Coupling of a disaccharide acceptor 13 with 12 afforded the heptasaccharide 14. Subsequent deprotection gave the heptaoside 16, while selective 2-O-deacetylation of 14 gave the heptasaccharide acceptor 15. Condensation of 15 with glucopyranosyluronate imidate 17 did not yield the expected octaoside, instead, an orthoester product 18 was obtained. Rearrangement of 18 did not give the target octaoside; but produced 15. Meanwhile, there was no reaction between 15 and the glycosyl bromide donor 19.

Acetylation↗
PubMed2004

Evaluation of different electrochemical methods on the oxidation and degradation of Reactive Blue 4 in aqueous solution.

The oxidation of a reactive dye, Reactive Blue 4, RB4, (C.I. 61205), widely used in the textile industries to color natural fibers, was studied by electrochemical techniques. The oxidation on glassy carbon electrode and reticulated vitreous carbon electrode occurs in only one step at 2.0 < pH < 12 involving a two-electron transfer to the amine group leading to the imide derivative. Dye solution was not decolorized effectively in this electrolysis process. Nevertheless, the oxidation of this dye on Ti/SnO2/SbO(x) (3% mol)/RuO2 (1% mol) electrode showed 100% of decolorization and 60% of total organic carbon removal in Na2SO4 0.2 M at pH 2.2 and potential of +2.4V. Experiments on degradation photoelectrocatalytic were also carried out for RB4 degradation in Na2SO4 0.1 M, pH 12, using a Ti/TiO2 photoanode biased at +1.0 V and UV light. After 1h of electrolysis the results indicated total color removal and 37% of mineralization.

Antimony↗
PubMed2005

Extraction properties of new polymeric sorbents in SPE/GC analysis of phenol and hydroquinone from water samples.

The influence of the polymers' properties on the solid-phase extraction recovery was studied. Different porous copolymers were used: di(methacryloyloxymethyl)naphtalene-divinylbenzene with ester functional groups (DMN-DVB), 4,4'-bis(maleimido)diphenylmethane-divinylbenzene with imide functional groups (BM-DVB), p,p'-dihydroxydiphenylmethane diglycidyl methacrylic ester-divinylbenzene (MEMDE-DVB) and p,p'-dihydroxydiphenylpropane diglycidyl methacrylic ester-divinylbenzene (MEDDE-DVB) with ester end hydroxyl functional groups. The extraction properties of new synthesized polymeric sorbents were compared with these of two commercial polymeric sorbents: styrene-divinylbenzene (SDB-1) and styrene-divinylbenzene with modified surface (StrataX). These sorbents were used in the SPE of phenol and hydroquinone from water samples.

Adsorption↗
PubMed2006

Nonaqueous capillary electrophoretic behavior of 2-aryl propionic acids in the presence of an achiral ionic liquid. A chemometric approach.

Ionic liquids (ILs) appear really attractive as electrolyte additives in nonaqueous capillary electrophoresis (NACE). These salts may offer new possibilities of interactions to modulate analyte effective mobilities. The presence of 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMIM NTf2) in acetonitrile/alcohol background electrolytes (BGEs) was investigated in this work. The aim of this study was to elucidate the influence of the IL concentration on the electrophoretic behavior of four arylpropionic acids and to identify the interactions between the analytes and the IL cation. The influence on mobility of the IL concentration, the nature and the proportion of the organic solvents, and the concentration of the ionic components of the BGE was first studied by a univariate approach. A four-factor D-optimal experimental design was then applied to provide a deeper insight into analyte interaction with IL cation present both free in BGE and adsorbed onto the capillary wall.

Carbazoles↗
PubMed2006

Evaluation of chiral ionic liquids as additives to cyclodextrins for enantiomeric separations by capillary electrophoresis.

A great interest has been drawn these last years towards ionic liquids in analytical chemistry, especially for separation methods. Recent synthesis of chiral ILs opened the way of the evaluation of new potential selectors for enantiomeric separations. This work focused on the evaluation of two chiral ILs (ethyl- and phenylcholine of bis(trifluoromethylsulfonyl)imide) by CE. Particular selectivities are awaited by exploiting unique ion-ion or ion-dipole interactions and by tailoring the nature of the cation and the anion. To evaluate such phenomena, a study was carried out with anti-inflammatory drugs 2-arylpropionic acids as model compounds. The results show that these chiral ILs did not present direct enantioselectivity with regard to these model analytes. The influence of chiral ILs in the electrolytes was then studied in the presence of classical chiral selectors (di- or trimethyl-beta-cyclodextrin). Although no general trend could be established, an increase in separation selectivity and resolution was observed in some cases, suggesting synergistic effects. The complementary determination of apparent inclusion constant values of these IL cations in the used cyclodextrins by affinity CE provided support to the understanding of the phenomena involved.

Cyclodextrins↗
PubMed2005

Bioreversible quaternary N-acyloxymethyl derivatives of the tertiary amines bupivacaine and lidocaine--synthesis, aqueous solubility and stability in buffer, human plasma and simulated intestinal fluid.

Design of water-soluble prodrugs may constitute a means to improve the oral bioavailability of drugs suffering from dissolution rate-limited absorption. The model drug bupivacaine containing a tertiary amine function has been converted into bioreversible quaternary N-acyloxymethyl derivatives. The pH-independent solubility of the N-butanoyloxymethyl derivate exceeded 1000 mg ml-1 corresponding approximately to a 10,000-fold increase in water solubility compared to that of bupivacaine base. The kinetics of hydrolysis of the prodrugs was studied in the pH range 0.1-9.8 (37 degrees C). Decomposition was found to follow first-order kinetics and U-shaped pH-rate profiles were constructed. The observed differences between the hydrolytic lability of the derivatives might most likely be ascribed to steric effects. In most cases, the prodrugs were quantitatively converted into bupivacaine. However, for the hydrolysis of the N-butanoyloxymethyl derivative at neutral to slightly alkaline pH parallel formation of bupivacaine (approximately 80%) and an unknown compound X (approximately 20%) was observed. LC-MS analysis of the latter compound suggests that an aromatic imide structure has been formed from an intramolecular acyl transfer reaction involving a nucleophilic attack of the amide nitrogen atom on the ester carbonyl carbon atom. Whereas the derivatives were poor substrates for plasma enzymes; they were hydrolyzed rapidly to parent bupivacaine in the presence of pancreatic enzymes (simulated intestinal fluid) at 37 degrees C. The data indicate that such prodrugs possess sufficient stability in the acidic environment of the stomach to reach the small intestine in intact form where they can be cleaved efficiently by action of pancreatic enzymes prior to drug absorption. Thus, the N-acyloxymethyl approach might be of potential utility to enhance oral bioavailability of tertiary amines exhibiting pKa values below approximately 6 and intrinsic solubilities in the low microM range.

Buffers↗
PubMed2004

Investigations on the synthesis and pharmacological properties of N-substituted derivatives of 4-alkoxy-6-methyl-1H-pyrrolo[3,4-c]pyridine-1,3(2H)-diones.

Synthesis of N-substituted derivatives of 4-alkoxy-6-methyl-1H-pyrrolo[3,4-c]pyridine-1,3(2H)-diones (10-14, 18-21) is described. In the "writhing syndrome" test all compounds studied exhibited potent analgesic activity which was superior than that of acetylsalicylic acid. In the "hot plate" test imides 10, 12, 13, 18-20 acted also stronger than aspirin. Furthermore all compounds tested significantly suppressed the spontaneous locomotor activity of mice and prolonged barbiturate sleep of these animals.

Analgesia↗
PubMed2005

Cycloimide bacteriochlorin p derivatives: photodynamic properties and cellular and tissue distribution.

Reactive oxygen species generated by photosensitizers are efficacious remedy for tumor eradication. Eleven cycloimide derivatives of bacteriochlorin p (CIBCs) with different N-substituents at the fused imide ring and various substituents replacing the 3-acetyl group were evaluated as photosensitizers with special emphasis on structure-activity relationships. The studied CIBCs absorb light within a tissue transparency window (780-830 nm) and possess high photostability at prolonged light irradiation. The most active derivatives are 300-fold more phototoxic toward HeLa and A549 cells than the clinically used photosensitizer Photogem due to the substituents that improve intracellular accumulation (distribution ratio of 8-13) and provide efficient photoinduced singlet oxygen generation (quantum yields of 0.54-0.57). The substituents predefine selective CIBC targeting to lipid droplets, Golgi apparatus, and lysosomes or provide mixed lipid droplets and Golgi apparatus localization in cancer cells. Lipid droplets and Golgi apparatus are critically sensitive to photoinduced damage. The average lethal dose of CIBC-generated singlet oxygen per volume unit of cell was estimated to be 0.22 mM. Confocal fluorescence analysis of tissue sections of tumor-bearing mice revealed the features of tissue distribution of selected CIBCs and, in particular, their ability to accumulate in tumor nodules and surrounding connective tissues. Considering the short-range action of singlet oxygen, these properties of CIBCs are prerequisite to efficient antitumor photodynamic therapy.

Adenocarcinoma↗