A sensitive LC-MS assay using derivatization with boron trifluoride to quantify curcuminoids in biological samples.

A procedure is described to measure curcumin (C), demethoxycurcumin (DMC), bisdemethoxycurcumin (BDMC), tetrahydrocurcumim (TC) and their glucuronidated metabolites (CG, DMCG, and BDMCG) in plasma, brain, liver and tumor samples. The procedure involves converting the analytes to their boron difluoride derivatives and analyzing them by combined liquid chromatography coupled to an ion trap mass spectrometer operating in the negative ion MSn scan mode. The method has superb limits of detection of 0.01 nM for all curcuminoids and 0.5 nM for TC and the glucuroniated metabolites, and several representative chromatograms of biological samples containing these analytes are provided. In addition, the pharmacokinetic profile of these compounds in one human who daily consumed an over-the-counter curcuminoid product shows the peak and changes in circulating concentrations achieved by this mode of administration.

Pharmacokinetics and Tissue Distribution of Alnustone in Rats after Intravenous Administration by Liquid Chromatography-Mass Spectrometry.

Alnustone, a nonphenolic diarylheptanoid, first isolated from Alnus pendula (Betulaceae), has recently received a great deal of attention due to its various beneficial pharmacological effects. However, its pharmacokinetic profile in vivo remains unclear. The purpose of this study is to establish a fast and sensitive quantification method of alnustone using liquid chromatography tandem mass spectrometry (LC-MS/MS) and evaluate the pharmacokinetic and tissue distribution profiles of alnustone in rats. The sample was precipitated with acetonitrile with 0.5% formic acid and separated on BEH C18 Column. The mobile phase was composed of 0.1% formic acid in water and methanol at a flow rate of 0.3 mL/min. Alnustone and the internal standard (caffeine) were quantitatively monitored with precursor-to-product ion transitions of m/z 262.9→105.2 and m/z 195.2→138.0, respectively. The calibration curve for alnustone was linear from 1 to 2000 ng/mL. The intra- and inter-day assay precision (RSD) ranged from 1.1-9.0 % to 3.3-8.6%, respectively and the intra- and inter-day assay accuracy (RE) was between -8.2-9.7% and -10.3-9.9%, respectively. The validated method was successfully applied to the pharmacokinetic studies of alnustone in rats. After single-dose intravenous administration of alnustone (5 mg/kg), the mean peak plasma concentration (Cmax) value was 7066.36 ± 820.62 ng/mL, and the mean area under the concentration-time curve (AUC0-t) value was 6009.79 ± 567.30 ng/mL∙h. Our results demonstrated that the residence time of alnustone in vivo was not long and it eliminated quickly from the rat plasma. Meanwhile, the drug is mainly distributed in tissues with large blood flow, and the lung and liver might be the target organs for alnustone efficacy. The study will provide information for further application of alnustone.

Development and validation of an LC-MS/MS method for the determination of DPHB in rat plasma and its application in pharmacokinetic studies.

The aim of the present study was to develop a rapid, specific and sensitive LC-MS/MS method for the determination of DPHB [7-(4″-hydroxy-3″-methoxyphenyl)-1-phenyl-4-hepten-3-one] in rat plasma using yakuchinone A as an internal standard (IS). n-Hexane was used for the extraction of DPHB from rat plasma. Chromatographic separation of DPHB was achieved using a Kinetex XB-C18 column (2.10 × 50 mm, 2.6 µm) at 40°C. The mobile phase consisted of water (containing 0.1‰ formic acid, A) and acetonitrile (containing 0.1‰ formic acid, B) under a gradient elution at a flow rate of 0.3 mL min-1 . Positive electrospray ionization and multiple reaction monitoring mode were used for detection. The selected precursor ion to product ion pairs, m/z 311.3 → 137.0 for DPHB and m/z 313.1 → 137.0 for yakuchinone A, were monitored. Good linearity was observed over the concentration range from 2 to 2000 ng mL-1 (r = 0.9969). The recovery efficiency of DPHB from rat plasma was 54.8-69.7%, while the matrix effect ranged from 99.7 to 113%. Intra- and inter-day precision and accuracy values were within ±15% at three different quality control concentration levels. This validated method was successfully applied to pharmacokinetic studies in rats after a single p.o. or i.v. dose of DPHB solution. The route of administration significantly influenced systemic exposure to DPHB, and low bioavailability of DPHB was observed. The method developed here will be further improved and used in future pharmacokinetic studies.

Determination of a novel diarylheptanoid (Juglanin B) from green walnut husks (Juglans regia L.) in rat plasma by high-performance liquid chromatography.

A simple and reliable analytical method based on high-performance liquid chromatography (HPLC) coupled with a diode array detector (DAD) was developed for the determination of a novel diarylheptanoid (Juglanin B) from green walnut husks (Juglans regia L.) in rat plasma using rhoiptelol as an internal standard. Chromatographic separation was carried out on a Sinochrom ODS-AP C(18) column (250 x 4.6 microm i.d., 5 mm) with acetonitrile-10 mM postassium dihydrogen phosphate (pH = 3; 55:45, v/v) as mobile phase, and the detection wavelength was set at 214 nm. The plasma samples were prepared using methanol as protein precipitator. The extraction recovery of Juglanin B ranged from 70.26 to 78.59%, and the calibration curve had a good linearity in the range 0.08-50 microg/mL (r(2) = 0.9932). The RSDs of intra- and inter-day precision ranged from 1.19 to 4.92% and 4.35 to 4.54%, respectively. The HPLC-DAD method described is a simple, rapid and reliable method for the determination of Juglanin B level and for use in studies involving pharmacokinetics.