Zhuan Hong

Simultaneous Determination of Fucoxanthin and Its Deacetylated Metabolite Fucoxanthinol in Rat Plasma by Liquid Chromatography-Tandem Mass Spectrometry

Fucoxanthin and its deacetylated metabolite fucoxanthinol are two major carotenoids that have been confirmed to possess various pharmacological properties. In the present study, fucoxanthinol was identified as the deacetylated metabolite of fucoxanthin, after intravenous (i.v.) and intragastric gavage (i.g.) administration to rats at doses of 2 and 65 mg/kg, respectively, by liquid chromatography-tandem mass spectrometric (LC-MS/MS) analysis. Next, an accurate and precise LC-MS/MS method was developed to quantitatively determine fucoxanthin and fucoxanthinol in rat plasma. Plasma samples were resolved by LC-MS/MS on a reverse-phase SB-C18 column that was equilibrated and eluted with acetonitrile (A)/aqueous 0.1% formic acid (B; 92/8, v/v) at a flow rate of 0.5 mL/min. Analytes were monitored by multiple-reaction monitoring (MRM) under positive electrospray ionization mode. The precursor/product transitions (m/z) were 659.3→109.0 for fucoxanthin, 617.2→109.0 for fucoxanthinol, and 429.4→313.2 for the internal standard (IS). Calibration curves for fucoxanthin and fucoxanthinol were linear over concentrations ranging from 1.53 to 720 and 1.17 to 600 ng/mL, respectively. The inter- and intraday accuracy and precision were within ±15%. The method was applied successfully in a pharmacokinetic study and the resulting oral fucoxanthin bioavailability calculated.

Determination of fucoxanthinol in rat plasma by liquid chromatography-tandem mass spectrometry

HighlightsA rapid, reliable, and sensitive LC–MS/MS method for determination of fucoxanthinol in rat plasma is described for the first time.Rats were administered fucoxanthinol (i.g. and i.v.) and the pharmacokinetic parameters of fucoxanthinol were observed.This study provides preliminary pharmacokinetic information regarding fucoxanthinol and it may be used for future pharmacology studies. Abstract Previous studies have indicated that dietary fucoxanthin is mainly converted into fucoxanthinol (the deacetylated form) in mammals, but the pharmacokinetics of fucoxanthinol remains unknown. In this study, after intravenous (i.v.) and intragastric gavage (i.g.) administration of fucoxanthinol to rats at 0.8 and 20 mg/kg respectively, one‐step protein precipitation with methanol was employed to prepared plasma samples, and an accurate and precise liquid chromatography‐tandem mass spectroscopy (LC–MS/MS) method was developed to determine fucoxanthinol. Plasma samples were resolved by LC–MS/MS on a reverse‐phase SB‐C18 column equilibrated and eluted with acetonitrile (A, 0.1% formic acid) and water (B, 0.1% formic acid) (A:B = 92:8, v/v) at a flow rate of 0.5 mL/min and the injection volume was 5 &mgr;L. Analytes were monitored by Selected‐reaction monitoring in positive electrospray ionization mode. The calibration curves for fucoxanthinol were linear over the range 1.17–300 ng/mL. The inter‐day and intra‐day accuracy and precision were within 1.55%–7.90%. The method was applied successfully in a pharmacokinetic study of fucoxanthinol and the resulting bioavailability was calculated.

Rapid Determination of Tetrodotoxin in Human Plasma by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry

A sensitive analytical method was developed to determine tetrodotoxin(TTX) in human plasma samples using protein precipitation, followed by ultra performance liquid chromatography(UPLC) analysis coupled with tandem mass spectrometry(MS/MS) using 11-deoxytetrodotoxin(11-deoxyTTX) as an internal standard. The plasma samples were prepared using protein precipitation prior to being analyzed by UPLC-MS/MS to identify TTX over a zwitterionic-hydrophilic interaction liquid chromatography column. The retention time values of TTX and 11-deoxyTTX were 4.12 and 3.67 min, respectively. TTX and 11-deoxyTTX were monitored and quantitated on the basis of their ion transitions for their respective precursor ions to their product ions(i.e., m/z 320.0→162.1 for TTX and m/z 304.0→176.0 for 11-deoxyTTX) in the multiple reaction-monitoring mode. The lower limit of quantification of this method was determined to be 0.0199 ng/mL. This method showed good linearity for plasma samples that contained TTX concentrations in the range of 0.0199—1.99 ng/mL. The specificity, precision, accuracy, matrix effect, and stability characteristics of this method were also examined. The intra-assay precision and accuracy ranged from 1.89% to 6.00% and from 92.21% to 100.00%, whereas the inter-assay precision and accuracy ranged from 0.64% to 7.75% and from 99.38% to 101.26%, respectively. This new method therefore represents a rapid, accurate, reliable, and highly sensitive method for the qualitative and quantitative analyses of a trace amount of TTX in human plasma samples.

Determination of trehalose by ion chromatography and its application to a pharmacokinetic study in rats after intramuscular injection

An ion chromatography method was established for detecting trehalose in rat plasma. The samples were analyzed using a CPMA1 column (250 × 4.0 mm, Thermo) with 120 mm NaOH as eluent at a flow rate of 0.7 mL/min. The standard curve was y = 1.4316x - 0.0654 (R = 0.9992), and the linear range was 0.2-10 mg/L. The relative standard deviations of within-run and between-run precisions at low, medium and high concentrations were within 0.96-8.33%, and the accuracy was within 80.09-114.99%. The method was verified by rigorous methods, and applied to a pharmacokinetic study in rats after intramuscular injection (20 mg/kg, n = 6). The pharmacokinetic parameters, specifically AUC0-t , AUC0-∞ , t1/2 , CL and Vd , were 15.542 ± 3.122 mg h/L, 15.599 ± 3.141 mg h/L, 0.73 ± 0.347 h, 1.331 ± 0.293 L/h kg and 1.403 ± 0.735 L/kg, respectively. The developed ion chromatography method met the requirements of biological sample measurement, and will be helpful for future pharmacological studies of trehalose.

Separation of antiviral nucleoside phosphoramidate diastereomers by analytical supercritical fluid chromatography

GRAPHICAL ABSTRACT ABSTRACT Two amino acid phosphoramidates with high antiviral activity were used as model compounds and separated using supercritical fluid chromatography on an achiral Hypersil BDS cyano column (250 × 4.6 mm, 5 µm). Supercritical CO2 was used as a mobile phase with different co-solvents, including methanol, ethanol, and 2-propanol. Several key processing parameters were evaluated, including the type and concentration of alcohol modifier (5 to 15%), backpressure (100 to 200 bar), and column temperature (30 to 45 ˚C) in terms of their impact on retention factor, diastereoselectivity, and resolution. The optimized chromatographic conditions allowed for a complete separation of mixture of two diastereomers with good resolution over a short time (5–9 min). At a backpressure of 150 bar and a temperature of 33°C, the diastereomers of phenylalanine methyl ester phenyl 5′-phosphoamidate of d4T (d4T-P-N-PheOMe) and alanine methyl ester phenyl 5′-phosphoamidate of d4T (d4T-P-N-AlaOMe) were separated with resolutions of 4.43 and 2.55 using 10.0% and 5.0% (v/v) methanol, respectively.

Diisopropyl [(4-meth­oxy­benzamido)(p-tol­yl)meth­yl]phospho­nate

The asymmetric unit of the title compound, C22H30NO5P, contains two independent molecules in which the dihedral angles between the benzene rings are 82.0 (2) and 78.4 (2)°. In the crystal, each molecule forms an inversion dimer via a pair of N—H⋯O(=P) hydrogen bonds.