On‐column capillary electrophoretic monitoring of rapid reaction kinetics for determination of the antioxidative potential of various bioactive phenols

Abstract

An on-column capillary electrophoretic procedure for the determination of the antioxidative potential of various bioactive phenols, found in plant, fruit, and vegetable extracts, is described. The assay is based on a rapid mixing of phenols or phenolic extracts before the capillary, followed by pressurized injection of the reaction mixture into the capillary. After incubation of the reaction mixture inside the capillary, high voltage is switched on and separation of reactants and products is performed. Using hydrogen peroxide as a stressor, the kinetics of the oxidation of various bioactive phenols was studied (rutin, chlorogenic acid, quercetin, caffeic acid, gallic acid, and combinations of these) and compared with the oxidation rate of L-ascorbic acid as a reference. The concept was demonstrated for the determination of the antioxidative potential of various polyphenol mixtures and of the methanol extract of the sea buckthorn (Hippophae rhamnoides L.). In most cases quercetin has the highest rate constant of oxidation among the tested phenolic compounds. However, in the mixture L-ascorbic acid/quercetin, the oxidation rate of L-ascorbic acid was enhanced and oxidation of quercetin was strongly inhibited compared with the other combinations of tested polyphenols.

Characterization of the antioxidative activity of novel nontoxic neuropeptides by using capillary electrophoresis

“…The time necessary for the complete separation of H 2 O 2 from the reactants can be estimated by the formula [27] Dt ¼ 2w…”

“…Recently, the qualitative and quantitative determination of GSSG and GSH was performed simultaneously using CE [23][24][25]. To date, only a few researchers have determined the oxidation rate constants by CE [26,27].…”

Recent trends in the determination of polyphenols by electromigration methods

“…Recently paper dealing with the on-column monitoring of reaction kinetics for the determination of antioxidation potential of various polyphenols was published [47]. Both antioxidants and hydrogen peroxide were introduced into the CZE capillary by means of autosampler.…”

Monitoring Organic Reactions by Micellar Electrokinetic Chromatography

“…It possesses advantages such as high efficiency, high speed, ease to be automated, low sample consumption, low cost, and multimode availability. After decades of development, CE plays important roles in the fields of chemistry, biology, pharmaceutical, environment, toxicology, medicine, and forensic chemistry [2][3][4][5][6][7][8][9][10].…”

“…CE is a method which can analyze charged analytes in aqueous solution. CE could also be an important method to analyze chemical reactions, playing a role in the research of reaction kinetics [5,12], asymmetric transformation of amino acids [13,14], catalytic oxidation [15], assembling of nanoparticles [16], protein interaction [17], and polymerase chain reaction (PCR) [18][19][20]. One of the modes of CE, micellar electrokinetic chromatography (MEKC), introduced surfactants as pseudostationary phases.…”