Identification of impurities in artemisinin, their behavior in high performance liquid chromatography and implications for the quality of derived anti-malarial drugs.

Previous work [1] on the HPLC analysis of artemisinin tentatively identified the two impurities present above trace levels. This identification was based on LC-MS results and NMR of impurities isolated from artemisinin. In this work the impurities have been synthesized allowing verification of their identity by LC-MS.

Specific targeting of highly conserved residues in the HIV-1 reverse transcriptase primer grip region. 2. Stereoselective interaction to overcome the effects of drug resistant mutations.

Starting from the prototypic compound 4, we describe new, potent, and broad-spectrum pyrrolobenzo(pyrido)oxazepinones antivirals. A biochemical and enzymological investigation was performed for defining their mechanism of inhibition at either recombinant HIV-1 RT wild type and non-nucleoside reverse transcriptase inhibitors (NNRTIs)-resistant mutants. For the novel compounds (S)-(+)-5 and (S)-(-)-7, a clear-cut stereoselective mechanism of enzyme inhibition was found.

On-column epimerization of dihydroartemisinin: an effective analytical approach to overcome the shortcomings of the International Pharmacopoeia monograph.

We developed a cryo-HPLC/UV method for the simultaneous determination of artemisinin (1), alpha-dihydroartemisinin (2alpha), beta-dihydroartemisinin (2beta), and a ubiquitous thermal decomposition product of 2 (designated as diketoaldehyde, 3), starting from the International Pharmacopoeia monograph on dihydroartemisinin. The method takes for the first time the on-column epimerization process of 2 into consideration. Chromatographic separation was obtained under reversed-phase conditions on a Symmetry C18 column (3.

Enantioselective liquid chromatographic-electrospray mass spectrometric assay of beta-adrenergic blockers: application to a pharmacokinetic study of sotalol in human plasma.

An enantioselective high performance liquid chromatographic-electrospray ionization mass spectrometric (HPLC-ESI-MS) method for the direct determination of several beta-adrenergic blockers was developed and validated. The method is based on the direct separation of the enantiomers of drugs on a laboratory-made chiral stationary phase (CSP) containing covalently bonded teicoplanin (TE) as chiral selector. Detection of the effluent was performed by electrospray ionization mass spectrometry, run in the selected-ion recording (SIR) mode.