Determination of Nobiletin in Rat Plasma after Ingestion of <i>Citrus depressa</i> Juice by Capillary Liquid Chromatography with Electrochemical Detection Using Boron-doped Diamond Electrode

Abstract

Voltammetric detection using a boron doped diamond (BDD) electrode coupled with capillary liquid chromatography (CLC) was developed for determining nobiletin, one of the polymethoxyflavones (PMFs), in plasma samples. CLC with electrochemical detection (CLC-ECD) was performed using a capillary octadecylsilica (ODS) column, wateracetonitrile-phosphoric acid (65:35:0.5, v/v/v), as a mobile phase, and an applied potential at +1.45 V vs. Ag/AgCl. Chromatographic peak heights were found linearly related to the amounts of nobiletin injected from 0.48 pg to 0.40 ng (r = 0.999). The detection limit (S/N = 3) was 0.13 pg. The concentrations of nobiletin in rat plasma after oral ingestion of 5.0 mL kg −1 Citrus depressa juice, corresponding to 0.17 mg kg −1 nobiletin, were determined to obtain a concentration-time profile of nobiletin by the present CLC-ECD method, which required only 30 µL of plasma sample for each time point. Based on the concentration-time profile of nobiletin in the rat plasma, the pharmacokinetic parameters of maximum drug concentration (C max ), maximum drug concentration time (t max ), and area under the concentration-time curve (AUC 0-3 h ) were obtained.

3‐Nitro‐2‐pyridinesulfenates as Efficient Solution‐ and Solid‐Phase Disulfide Bond Forming Agents

“…To understand the oxidizability of Npys‐OMe ( 3 a ) during disulfide formation, its reduction peak potential ( E pc ) was measured by cyclic voltammetry in CH 3 CN and 20 m m phosphate buffer (pH 6.0, 1:3, v/v) containing 0.1 m KCl as an electrolyte solution. The E pc value of 3 a (1.0 m m ) was −0.541 V versus Ag/AgCl, which is more positive than that of oxidized glutathione (−1.55 V vs. Ag/AgCl, 4.0 m m ).…”

Nobiletin enhances plasma Interleukin‐6 and C‐X‐C motif chemokine ligand 1 levels that are increased by treadmill running

“…a,b,c Values not sharing a common letter differed significantly at p < .05 by the Tukey-Kramer test the in vitro experiment (Figure 3). Plasma concentrations of nobiletin on the order of microgram/milliliter (μg/ml) are thought to be achievable, because the maximum plasma concentration (Cmax) of nobiletin in rats reaches 56 ng/ml when nobiletin at only 0.17 mg/ kg body weight is given (Kotani et al, 2015). We quantified epinephrine and norepinephrine in this study, and their plasma concentrations (epinephrine, >0.4 ng/ml; norepinephrine,> 4 ng/ml) are comparable to those in the in vitro experiment.…”