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p. 2434-2449
Received: 21 August 2007; in revised form: 9 October 2007 / Accepted: 21 October 2007 / Published: 1 November 2007
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| Download PDF Full-text (176 KB) Abstract: A dopamine-imprinted polymer (MIP) was prepared in aqueous methanolsolution at 60o C by free-radical cross-linking polymerization of methacrylic acid in thepresence of ethylene glycol dimethacrylate as the cross-linker and dopamine hydrochlorideas the template molecule. Its ability to isolate dopamine was evaluated as the basis of asolid phase extraction procedure and compared with that of a non-imprinted polymer(NIP). The binding of dopamine was 84.1% and 29.1% for MIP and NIP, respectively.Various reported post-polymerization treatments to reduce template bleeding wereexamined. In our case the lowest bleeding was achieved after applying a combinedprocedure: continuous extraction in a Soxhlet apparatus (CE), followed by microwave-assisted extraction (ME) to a level of 0.061 μg/mL. A simplified model of the template-monomer complexes allowed rationalization of monomer choice based on the heats ofcomplex formation at a PM3 level of theory.
p. 2450-2457
Received: 9 August 2007; in revised form: 9 October 2007 / Accepted: 9 October 2007 / Published: 6 November 2007
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| Download PDF Full-text (91 KB) Abstract: A series of six novel 5-fluorouracil derivatives 1-6 were synthesized and theirstructures confirmed by 1 H- and 13 C-NMR, MS and elemental analysis. The preliminary invitro antitumor activities against B16, K562 and CHO cells and the in vivo inhibitions ofliver cancer H22 demonstrated that some of these compounds effectively inhibit the growthof tumor cells, but the in vivo trials in mice revealed that the compounds also exhibitedserious liver and lung tissue toxicity. The hydrolysis experiments indicated that this type ofcompound did not readily liberate 5-fluorouracil, as expected.
p. 2458-2466
Received: 1 October 2007; in revised form: 1 November 2007 / Accepted: 1 November 2007 / Published: 9 November 2007
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| Download PDF Full-text (69 KB) Abstract: A facile and efficient protocol is reported for the synthesis of calix[4]pyrrolesand N-confused calix[4]pyrroles in moderate to excellent yields by reaction of dialkyl orcycloalkyl ketones with pyrrole catalyzed by reusable AmberlystTM -15 under eco-friendlyconditions.
p. 2467-2477
Received: 31 July 2007; in revised form: 22 October 2007 / Accepted: 31 October 2007 / Published: 12 November 2007
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| Download PDF Full-text (81 KB) Abstract: 2-Aminobenzothiazole-6-carboxylic acid (1), on condensation with chloroacetylchloride yielded 2-(2-chloroacetylamino)benzothiazole-6-carboxylic acid (2), which onamination with hydrazine hydrate yielded in turn 2-(2-hydrazinoacetylamino)benzo-thiazole-6-carboxylic acid (3). Compound 3, on condensation with various aromaticaldehydes afforded a series of 2-{2-[N’-(arylidene)hydrazino]acetylamino}benzothiazole-6-carboxylic acids 4a-h, which upon dehydrative annulation in the presence ofchloroacetyl chloride and triethylamine yielded 2-{2-[3-chloro-2-(aryl)-4-oxoazetidin-1-ylamino]-acetylamino}benzothiazole-6-carboxylic acids 5a-h. The synthesized compounds4a-h and 5a-h were screened for their antibacterial activity against four microorganisms:Staphylococcus aureus (Gram positive), Bacillus subtilis (Gram positive), Psuedomonasaeruginosa (Gram negative) and Escherichia coli (Gram negative). They were found toexhibit good to moderate antibacterial activity. The antifungal activity of these compoundswere also tested against three different fungal species. None of them were active againstthe species tested.
p. 2478-2483
Received: 19 October 2007; in revised form: 6 November 2007 / Accepted: 6 November 2007 / Published: 12 November 2007
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| Download PDF Full-text (64 KB) Abstract: Certain substituted bromobenzenes have been synthesized in acceptable yieldsusing a novel Sandmeyer type reaction. The reactions are relatively quick and possiblyproceed via a radical mechanism.
p. 2484-2506
Received: 6 October 2007; in revised form: 8 November 2007 / Accepted: 9 November 2007 / Published: 12 November 2007
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| Download PDF Full-text (167 KB) Abstract: Many drugs suffer from an extensive first-pass metabolism leading to druginactivation and/or production of toxic metabolites, which makes them attractive targets forprodrug design. The classical prodrug approach, which involves enzyme-sensitive covalentlinkage between the parent drug and a carrier moiety, is a well established strategy toovercome bioavailability/toxicity issues. However, the development of prodrugs that canregenerate the parent drug through non-enzymatic pathways has emerged as an alternativeapproach in which prodrug activation is not influenced by inter- and intraindividualvariability that affects enzymatic activity. Cyclization-activated prodrugs have beencapturing the attention of medicinal chemists since the middle-1980s, and reached maturityin prodrug design in the late 1990s. Many different strategies have been exploited in recentyears concerning the development of intramoleculary-activated prodrugs spanning fromanalgesics to anti-HIV therapeutic agents. Intramolecular pathways have also a key role intwo-step prodrug activation, where an initial enzymatic cleavage step is followed by acyclization-elimination reaction that releases the active drug. This wor
(This article belongs to the Special Issue
Prodrugs )
p. 2507-2514
Received: 24 May 2007; in revised form: 6 August 2007 / Accepted: 6 August 2007 / Published: 13 November 2007
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| Download PDF Full-text (130 KB) Abstract: The synthesis of optically active [N-tosyl-(R)-prolyloxy]-2(S)-[4-cyano-8,8-ethylenedioxy-5-oxo-5,6,7,8-tetrahydroindolizin-3-yl] acetate (4a), a key intermediate forthe total asymmetric synthesis of 20(S)-camptothecin anticancer drugs, is described. Itsstructure was characterized by 2D-NMR techniques and the absolute configuration wasfurther confirmed for the first time by X-ray crystal structure analysis.
p. 2515-2532
Received: 29 September 2007; in revised form: 13 November 2007 / Accepted: 13 November 2007 / Published: 15 November 2007
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| Download PDF Full-text (461 KB) Abstract: Sulfated zirconia and SZ/MCM-41 were used as catalysts for the synthesis of β-aminoalcohols via epoxide aminolysis. Sulfated zirconia was prepared by sol-gel andSZ/MCM-41 was obtained by impregnation. Solid catalysts were characterized by XRD,SEM-EDS, UV-Vis, FT-IR pyridine desorption and Nitrogen physisorption. Both acidmaterials were useful as catalysts, even when they were recycled several times. The β-aminoalcohols were characterized by FT-IR, 1 H- and 13 C-NMR and GC-MS.
p. 2533-2545
Received: 30 October 2007; in revised form: 15 November 2007 / Accepted: 15 November 2007 / Published: 17 November 2007
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| Download PDF Full-text (85 KB) Abstract: A feasibility and chemical study of the coupling conditions of L-ascorbic acidwith ferulic acid derivatives are described on the basis of the known synergistic effects ofmixtures of various antioxidants. Novel L-ascorbic ferulic hybrids linked at the C-3hydroxyl group were prepared with the aim to protect the alcohol function and the enediolsystem.
p. 2546-2558
Received: 9 November 2007; in revised form: 22 November 2007 / Accepted: 23 November 2007 / Published: 26 November 2007
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| Download PDF Full-text (104 KB) Abstract: Hantzsch condensation of two equivalents of methyl-3-aminocrotonate with (m-and p)-methoxybenzaldehyde afforded the expected products 2,6-dimethyl-3,5-dimethoxycarbonyl-4-(m-methoxyphenyl)-1,4-dihydropyridine and 2,6-dimethyl-3,5-dimethoxycarbonyl-4-(p-methoxyphenyl)-1,4-dihydropyridine, whereas o-methoxy-benzaldehyde produced mainly 1-amino-2-methoxycarbonyl-3,5-bis(o-methoxy-phenyl)-4-oxa-cyclohexan-1-ene. The structure of the product, not previously reported in theliterature, was determined by 1D and 2D NMR spectra and its MS fragmentation. This isthe first example of cyclisation leading to a substituted pyran rather than 1,4-DHP undertypical Hantzsch reaction conditions. A plausible mechanism for its formation ispostulated.
p. 2559-2566
Received: 17 November 2007; in revised form: 27 November 2007 / Accepted: 27 November 2007 / Published: 29 November 2007
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| Download PDF Full-text (117 KB) Abstract: Calcium-induced alginate gel bead (Alg-Ca) coated with an alginate hydrolysate(Alg), e.g. the guluronic acid block (GB) was prepared and the model drug, hydrocortisonerelease profiles were investigated under simulated gastrointestinal conditions. Theirmolecular weights were one sixth or one tenth that of Alg and the diffraction patterns of thehydrolysates resembled that of Alg. The drug release rate from Alg-Ca coated with GBapparently lowered than that of Alg-Ca (coating-free) in the gastric juice (pH1.2). And thecoating did not resist the disintegration of Alg-Ca in the intestinal juice (pH 6.8) and thegel erosion accelerated the drug release. On the other hand, for the coated Alg-Cacontaining chitosan, the drug release showed zero-order kinetics without rapid erosion ofAlg-Ca. The drug release rate from Alg-Ca was able to be controlled by the coating andmodifying the composition of the gel matrix.
(This article belongs to the Special Issue
Prodrugs )
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