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1.
Molecules ; 28(22)2023 Nov 16.
Article in English | MEDLINE | ID: mdl-38005343

ABSTRACT

This review presents a description of the available data from the literature on the electrochemical properties of flavonoids. The emphasis has been placed on the mechanism of oxidation processes and an attempt was made to find a general relation between the observed reaction paths and the structure of flavonoids. Regardless of the solvent used, three potential regions related to flavonoid structures are characteristic of the occurrence of their electrochemical oxidation. The potential values depend on the solvent used. In the less positive potential region, flavonoids, which have an ortho dihydroxy moiety, are reversibly oxidized to corresponding o-quinones. The o-quinones, if they possess a C3 hydroxyl group, react with water to form a benzofuranone derivative (II). In the second potential region, (II) is irreversibly oxidized. In this potential region, some flavonoids without an ortho dihydroxy moiety can also be oxidized to the corresponding p-quinone methides. The oxidation of the hydroxyl groups located in ring A, which are not in the ortho position, occurs in the third potential region at the most positive values. Some discrepancies in the reported reaction mechanisms have been indicated, and this is a good starting point for further investigations.


Subject(s)
Flavonoids , Flavonoids/chemistry , Electrochemistry , Oxidation-Reduction , Solvents
2.
Food Chem ; 268: 567-576, 2018 Dec 01.
Article in English | MEDLINE | ID: mdl-30064798

ABSTRACT

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.


Subject(s)
Antioxidants/chemistry , Polyphenols/chemistry , Flavonols , Lipid Peroxidation
3.
Steroids ; 117: 44-51, 2017 01.
Article in English | MEDLINE | ID: mdl-27263439

ABSTRACT

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.


Subject(s)
Cholesterol/chemistry , Cholesterol/metabolism , Electrochemistry/methods , Glycosylation , Molecular Structure , Stereoisomerism
4.
Beilstein J Org Chem ; 11: 162-8, 2015.
Article in English | MEDLINE | ID: mdl-25815065

ABSTRACT

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.

5.
Eur J Pharm Sci ; 59: 1-11, 2014 Aug 01.
Article in English | MEDLINE | ID: mdl-24746680

ABSTRACT

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.


Subject(s)
Adrenergic beta-1 Receptor Antagonists/chemistry , Bisoprolol/chemistry , Glucose/chemistry , Lactose/chemistry , Maltose/chemistry , Chromatography, High Pressure Liquid , Drug Stability , Magnetic Resonance Spectroscopy , Maillard Reaction , Mass Spectrometry , Oxidation-Reduction , Spectrophotometry, Ultraviolet , Water/analysis
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