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1.
Food Chem ; 268: 567-576, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-30064798

RESUMO

Interaction of metal, especially iron ions with flavanols is considered as an important feature of these compounds and is believed to contribute to their both antioxidant and prooxidant properties. The aim of this study was to examine how Fe2+ binding to form a 4:1 (flavanol:Fe2+) mixtures affects the antioxidant properties of flavanols. ABTS∗ scavenging, protection against fluorescence bleaching induced by AAPH and hypochlorite, protection against lipid peroxidation and protection against hypochlorite-induced hemolysis demonstrated that flavonol-Fe2+ mixtures retain antioxidant properties, although, in most cases, they are lower with respect to the flavanols alone. No superoxide dismutase-like or catalase-like activity of the mixtures was revealed.


Assuntos
Antioxidantes/química , Polifenóis/química , Flavonóis , Peroxidação de Lipídeos
2.
Steroids ; 117: 44-51, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27263439

RESUMO

Electrochemical cholesterylation of various sugars with cholesteryl diphenylphosphate was studied. The reaction afforded mono-, di-, tri-, and tetra-cholesterylated products using equivalent amounts of the reagent. The reactions turned out to be completely stereoselective with respect to both sugar and steroid but only partially regioselective - primary and anomeric hydroxyl groups in sugars were the most reactive ones while no substantial differences in reactivity was found for different secondary hydroxyl groups.


Assuntos
Colesterol/química , Colesterol/metabolismo , Eletroquímica/métodos , Glicosilação , Estrutura Molecular , Estereoisomerismo
3.
Beilstein J Org Chem ; 11: 162-8, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25815065

RESUMO

3α,5α-Cyclocholestan-6ß-yl alkyl and aryl ethers were proved to be efficient cholesteryl donors in the electrochemical synthesis of glycoconjugates. 3α,5α-Cyclocholestan-6ß-ol (i-cholesterol) and its tert-butyldimethylsilyl ether can also be used for this purpose. The i-cholesterol derivatives show similar reactivities to those of previously studied 3α,5α-cyclocholestan-6ß-thioethers.

4.
Eur J Pharm Sci ; 59: 1-11, 2014 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-24746680

RESUMO

HPLC analysis of drug products containing bisoprolol fumarate and lactose revealed the presence of N-formylbisoprolol, which is a final product of the Maillard reaction. Formulations containing secondary amines and reducing carbohydrates are prone to the condensation of amine and carbonyl functional groups and formation of glycosylamines in pharmaceutically relevant conditions. Further rearrangement occurs in the presence of a nucleophile and leads to the formation of 1-deoxy-1-amino-2-ketose also known as the Amadori Rearrangement Product (ARP). The influence of water content, carbohydrate, and lubricant types on the reaction rate was tested. The reaction progress was monitored by HPLC and UV-Vis spectrophotometry. The structures of intermediates were confirmed by the LC/MS(2) analysis. N-formylbisoprolol - the final reaction product - was synthesised and characterised by LC/MS(2), H(1) and C(13) NMR.


Assuntos
Antagonistas de Receptores Adrenérgicos beta 1/química , Bisoprolol/química , Glucose/química , Lactose/química , Maltose/química , Cromatografia Líquida de Alta Pressão , Estabilidade de Medicamentos , Espectroscopia de Ressonância Magnética , Reação de Maillard , Espectrometria de Massas , Oxirredução , Espectrofotometria Ultravioleta , Água/análise
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