Chemical and bioassay techniques to authenticate quality of the anti-leishmanial drug miltefosine.

Miltefosine, an effective oral treatment of visceral leishmaniasis (VL), was selected in May 2005, by the governments of India, Nepal, and Bangladesh for the elimination of VL. However, abnormally high treatment failure rates reported in patients in Bangladesh, given a miltefosine generic product ("Miltefos", Popular Pharmaceuticals Ltd.) during 2008, led the World Health Organization (WHO) to procure this formulation for quality testing. Proton ((1)H) and phosphorous ((31)P) nuclear magnetic resonance (NMR) analyses of the Miltefos™ capsules did not give the peaks defined for Impavido®, the quality assured VL treatment product from Aeterna Zentaris. Contents of capsules of Impavido® yielded expected peaks for miltefosine (m/z 408.33 for the protonated parent ion and m/z 183.99 plus m/z 124.8 the fragment ions) that were absent in the Miltefos™ capsules. Furthermore, testing using an in vitro Leishmania donovani intracellular amastigote-macrophage model, yielded EC50 values of between 2.55 and 4.06 µg/mL and 3.02 to 5.92 µg/mL for extracts from the Impavido® capsules and the miltefosine standard, respectively. Lack of significant anti-leishmanial activity of Miltefos™ capsules was identified in this assay even at concentrations up to 100 µg/mL. Capsules of Miltefos™ were classified as falsified (absence of stated active pharmaceutical ingredient) by three methods-NMR and mass spectrometry analysis and bioassay.

Synthesis of enantiomerically pure isotopomers of 2-phenylpropionic acids.

A series of enantiomerically pure [D,(13)C]-labeled isotopomeric 2-phenylpropionic acids were efficiently synthesized using a diastereoselective alkylation and kinetic resolution strategy.

Parallel kinetic resolution of an oxazolidinone using a quasi-enantiomeric combination of [D,13C]-isotopomers of pentafluorophenyl 2-phenyl propionate.

Parallel kinetic resolution of Evans' phenylglycine derived oxazolidinone using an equimolar combination of quasi-enantiomeric active esters (derived from [D,13C]-labeled 2-phenylpropionic acid) was achieved. The levels of stereocontrol were high, leading to products with predictable configurations.

Mutual kinetic separation of isotopomers of pentafluorophenyl 2-phenyl propionate using quasi-enantiomeric oxazolidinones.

Mutual separation of an equimolar mixture of quasi-enantiomeric [D,13C]-labeled isotopomers of pentafluorophenyl 2-phenylpropionate can be achieved efficiently by use of two quasi-enantiomeric Evans' oxazolidinones. The levels of stereocontrol were high, leading to products with predictable configurations.

Stereoselective synthesis of (E)-mannosylidene derivatives using the Wittig reaction.

Stabilized ylides Bu(3)P=CH(EWG), where EWG is an ester or nitrile group, react with 2,3,4,6-tetra-O-benzylmannono-1,5-lactone giving high yields of mannosylidene derivatives; in contrast to the glucose and galactose analogues, the (E)-mannosylidenes are predominant (E:Z > 9:1), thus minimizing dipole-dipole repulsions in the Wittig reactions. NMR indicates chair-like conformations for solutions of the (E)-mannopyranosylidenes, but not for those (Z)-isomers where data are available (EWG = CN or CO(2)Et). X-ray crystallography shows an approximately twist-boat conformation for the tetra-O-benzyl-protected (Z)-mannosylideneacetonitrile.

(-)-Dimenthyl malonate.

The title compound, bis(2-isopropyl-5-methylcyclohex-1-yl) malonate, C(23)H(40)O(4), crystallizes in the monoclinic space group P2(1). In the crystal, the molecule is not C(2) symmetric.

The synthesis and structure of substituted dimenthyl malonate derivatives.

A series of substituted dimenthyl malonate derivatives were efficiently synthesized from dimenthyl malonate using a deprotonation and alkylation strategy. The elucidation of the structure of these derivatives were determined by a combination of X-ray crystallography, NMR and IR spectroscopy.