Burchellin and its stereoisomers: total synthesis, structural elucidation and antiviral activity.

Burchellin and its analogues are a class of neolignan natural products containing a rare core with three contiguous stereogenic centers. In previous reports, racemic burchellin was synthesized without accessing each of the enantiomers. In this paper, a concise and efficient total synthetic route to divergently access the enantiomers of burchellin and those of its 1'-epi-diastereoisomer over six steps for each is disclosed, where each of the enantiomers was obtained by preparative chiral phase HPLC purification.

[Determination of Desloratadine and Its Metabolite 3-OH Desloratadine in Human Plasma by LC-MS/MS].

Objective: To develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of desloratadine and its metabolite 3-OH desloratadine in human plasma.

Methods: 24 healthy male volunteers received a single oral dose of 5 mg desloratadine tablets in a randomized crossover bioequivalence study with two preparations of tablets. Serial plasma samples were taken and analyzed by the LC-MS/MS method.

[Simultaneous determination of adrenaline, noradrenaline, cortisone and cortisol in plasma with HPLC/MS/MS].

Objective: To develop a method for simultaneous determination of adrenaline, noradrenaline, cortisone and cortisol in plasma using HPLC/MS/MS.

Methods: Sample proteins were precipitated with acetonitrile and the sample solution was injected into HPLC/MS/MS after centrifugation at 15,000 r/min for 5 min. Electrospray ionization (ESI) and the positive ion detection were applied with a multiple reaction monitoring (MRM) mode for quantitative analyses.