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Chemical Delivery Systems (chemical + delivery_system)

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Chemistry	100%

Selected Abstracts

N -Malonyl-1,2-dihydroisoquinoline as a Novel Carrier for Specific Delivery of Drugs to the Brain

ARCHIV DER PHARMAZIE, Issue 1 2010
Mohamed Abdel-Aziz
Abstract N -Malonyl-1,2-dihydroisoquinoline derivatives were synthesized and investigated as a novel carrier system for site-specific and sustained delivery of drugs to the brain. Such carriers are expected to be stable against air oxidation due to the presence of the carbonyl group close to nitrogen of the dihydroisoquinoline. Reduction of the prepared isoquinolinium quaternary derivatives with sodium dithionite afforded a novel group of N -malonyl-1,2-dihydroisoquinoline chemical delivery systems (CDS). The synthesized N -malonyl-1,2-dihydroisoquinoline chemical delivery systems were subjected to various chemical and biological investigations to evaluate their ability to cross the blood-brain barrier (BBB), and to be oxidized biologically into their corresponding quaternary derivatives. The in-vitro oxidation studies showed that the designed N -malonyl-1,2-dihydroisoquinoline chemical delivery system could be oxidized into its corresponding quaternary derivatives at an adequate rate. The in-vivo distribution studies showed that these N -malonyl-1,2-dihydroisoquinoline chemical delivery systems were able to cross the blood-brain barrier at detectable concentrations. [source]

Light-induced controlled release of fragrance aldehydes from 1-alkoxy-9,10-anthraquinones for applications in functional perfumery,,

FLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2006
Barbara Levrand
Abstract Light-activated chemical delivery systems for the controlled release of fragrances have been shown to be effective in functional perfumery. Upon photolysis around 350 nm, 1-alkoxy-9,10-anthraquinones release aldehydes or ketones and may thus be considered as promising precursors for the photochemical release of perfume molecules. A series of substituted and unsubstituted mono- and dialkoxy-9,10-anthraquinones was prepared by reaction of the corresponding fragrance bromides with commercial mono- or dihydroxy-9,10-anthraquinones. Photoirradiation of these compounds in polar and apolar solution yielded the desired fragrance aldehydes. Preliminary olfactory panel evaluations on fabric after exposure to ambient indoor daylight for several days indicated a slightly stronger odour in the presence of the fragrance precursors, as compared to a reference sample containing the unmodified perfumery raw material. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Controlled Release of Perfumery Alcohols by Neighboring-Group Participation.

HELVETICA CHIMICA ACTA, Issue 8 2003
2-(Hydroxymethyl)-, 2-Carbamoylbenzoates, Comparison of the Rate Constants for the Alkaline Hydrolysis of 2-Acyl-
A series of 2-acylbenzoates 1 and 2, 2-(hydroxymethyl)benzoates 3, 2-carbamoylbenzoates 4,6, as well as the carbamoyl esters 7 or 8 of maleate or succinate, respectively (see Fig.,2), were prepared in a few reaction steps, and the potential use of these compounds as chemical delivery systems for the controlled release of primary, secondary, and tertiary fragrance alcohols was investigated. The rate constants for the neighboring-group-assisted alkaline ester hydrolysis were determined by anal. HPLC in buffered H2O/MeCN solution at different pH (Table,1). The rates of hydrolysis were found to depend on the structure of the alcohol, together with the precursor skeleton and the structure of the neighboring nucleophile that attacks the ester function. Primary alcohols were released more rapidly than secondary and tertiary alcohols, and benzoates of allylic primary alcohols (e.g., geraniol) were hydrolyzed 2,4 times faster than their homologous saturated alcohols (e.g., citronellol). For the same leaving alcohol, 2-[(ethylamino)carbonyl]benzoates cyclized faster than the corresponding 2-(hydroxymethyl)benzoates, and much faster than their 2-formyl and 2-acetyl analogues (see, e.g., Fig.,4). Within the carbamoyl ester series, 2-[(ethylamino)carbonyl]benzoates were found to have the highest rate constants for the alkaline ester hydrolysis, followed by unsubstituted 2-(aminocarbonyl)benzoates, or the corresponding isopropyl derivatives. To rationalize the influence of the different structural changes on the hydrolysis kinetics, the experimental data obtained for the 2-[(alkylamino)carbonyl]benzoates were compared with the results of density-functional computer simulations (Table,2 and Scheme,4). Based on a preliminary semi-empirical conformation analysis, density-functional calculations at the B3LYP/6-31G** level were carried out for the starting precursor molecules, several reaction intermediates, and the cyclized phthalimides. For the same precursor skeleton, these simple calculations were found to model the experimental data correctly. With an understanding of the influence of structural parameters on the rate constants obtained in this work, it is now possible to influence the rates of hydrolysis over several orders of magnitude, to design tailor-made precursors for a large variety of fragrance alcohols, and to predict their efficiency as controlled-release systems in practical applications. [source]