Multiple-Injection Capillary Zone Electrophoresis as a Fast Strategy to Determine Antinitrosating Capacity of Commercial Teas

Abstract

This paper describes the use of a multiple-injection capillary electrophoresis method as a fast strategy to determine the antinitrosating capacity of nine commercial teas through nitrite quantification. The method consists of the injection of the sample followed by the injection of the control solution, employing a fused-silica capillary of 32.0 cm total length (23.5 cm effective length, 50 µm internal diameter) with background electrolyte composed of 4.0 g L -1 β-alanine and 1.5 g L -1 perchloric acid (pH 3.79) and sodium thiocyanate was used as the internal standard. Before the injections the tea samples were maintained by 1 h of incubation, at 37 °C, with sodium nitrite in perchloric acid medium (pH 2.3). In order to avoid nitrite oxidation and nitrate formation, ultra-pure nearly oxygen-free water was used to prepare the solutions. Black tea, green tea and white tea, obtained from Camellia sinensis, showed greater antinitrosating capacity (96, 93 and 89%, respectively).

Alternative method for microenzymatic inhibition activities monitoring fromBaccharis trimeraextracts by CZE‐UV

“…The positive control was prepared with the same amount of p‐NPG and butylparaben, but 150 μl of acarbose and 250 μl of the buffer were added. In sample solutions, as well as in AChE inhibition, the standard inhibitors were replaced by 150 μl of the extracts 10,20 …”

“…In sample solutions, as well as in AChE inhibition, the standard inhibitors were replaced by 150 μl of the extracts. 10,20 The temperature was adjusted to 37 C, and the voltage used for the separation was 30 kV. The BGE used was borate-phosphate at a concentration of 30 mmol/L.…”

“…The properties of the phenolic compounds present in B. trimera may also be related to the ability of these compounds to inhibit enzymatic reactions, such as reactions of the enzymes acetylcholinesterase (AChE) and α‐glycosidase (α‐GLY). Thus, this plant is a rich source of compounds that can be useful for the treatment of pathologies related to these enzymes, such as Alzheimer's disease and diabetes 6,10,11 . In addition, these compounds might be candidates to be explored for modulating other biological disorders caused by oxidative stress, such as neurodegenerative and cardiovascular diseases and cancers 12,13 …”

“…Thus, this plant is a rich source of compounds that can be useful for the treatment of pathologies related to these enzymes, such as Alzheimer's disease and diabetes. 6,10,11 In addition, these compounds might be candidates to be explored for modulating other biological disorders caused by oxidative stress, such as neurodegenerative and cardiovascular diseases and cancers. 12,13 Classical methods, such as the spectrophotometric ultravioletvisible (UV-VIS) method and high-performance liquid chromatography (HPLC-UV), are the traditional approaches used to perform enzymatic activity studies from samples of phytochemical interest.…”

A simple and efficient sequential electrokinetic and hydrodynamic injections in micellar electrokinetic chromatography method for quantification of anticancer drug 5‐fluorouracil and its metabolite in human plasma

“…The method consists of the injection of the sample followed by the injection of the control solution at 50 mbar within 5 s each. Detection limits as low as 0.324 mg/L were obtained using the developed method (Ruani, Vitali, & Micke, 2018). Meanwhile, in micellar electrokinetic chromatography (MEKC), analytes are separated by differential partitioning between micelles and a surrounding aqueous BGE.…”