[(2R,3R)-3-(4-Nitro-phen-yl)aziridin-2-yl]methanol monohydrate.

The title monohydrate, C9H10N2O3·H2O, contains an aziridine ring including two contiguous stereocenters, both of which exhibit an R configuration. The methyl-hydroxy and nitro-phenyl groups are cis-disposed about the aziridine ring. The mean plane of the benzene ring is tilted to the aziridine ring by 66.65 (8)°. The nitro group is nearly coplanar with the benzene ring [dihedral angle = 2.5 (2)°]. In the crystal, the components are linked by N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds, generating supra-molecular layers parallel to (001).

(4S)-4-[(R)-Chloro-(4-nitro-phen-yl)meth-yl]-1,3-oxazolidin-2-one.

In the title compound, C10H9ClN2O4, the oxazolidinone ring adopts a near-planar conformation, with mean and maximum deviations of 0.0204 (8) and 0.0328 (8) Å, respectively. The nitro group is twisted slightly from the plane of the benzene ring, making a dihedral angle of 6.79 (3)°. The dihedral angle between the mean oxazolidinone plane and the benzene ring is 56.21 (3)°. In the crystal, N-H⋯O hydrogen bonds and N-O⋯π inter-actions [O⋯centroid distances = 3.478 (1) and 3.238 (1) Å] dominate the packing, forming infinite zigzag chains along the b-axis direction. Neighbouring chains are linked together through C-H⋯O and C-H⋯Cl inter-actions. The absolute configuration of the two stereogenic centres was determined using the anomalous dispersion of the Cl atom.

Synthesis and in vitro studies of pyrone derivatives as scavengers of active oxygen species.

The antioxidant properties of eleven alpha-pyrones and four gamma-pyrones were evaluated by means of three different tests: reduction of the stable free radical, 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion scavenging assay and lipid peroxidation assay. In the DPPH test, 6-aryl-5,6-dihydro-4-hydroxypyran-2-ones (3) and 4-hydroxypyran-2-one (5f) were the most active derivatives with IC50 values ranging from 36.7 to 394 mumol/l. Potent superoxide anion scavenging properties appeared in derivatives possessing phenol moieties. Thus phenolic pyrones 5e and 5f exhibited a noteworthy activity (IC50 = 0.180 and 0.488 mmol/l, respectively) when reference compound, ascorbic acid, demonstrated only 24% inhibition at a concentration of 1 mg/ml. In addition derivative 5f significantly inhibited the Fe2+/ADP/ascorbate-induced lipid peroxidation of rat liver microsomes with an IC50 value of 0.069 mmol/l. Due to its multiple mechanism of protective action, compound 5f may be useful for the treatment of oxidative tissue injury in human disease.

Gas chromatographic-mass spectrometric determination of isosorbide 5-mononitrate in human plasma.

A highly specific and precise method using gas chromatography-mass spectrometry was developed for the measurement of isosorbide 5-mononitrate in plasma using isomannide mononitrate as internal standard. With regard to the numerous analytical problems encountered when organic mononitrates were determined in plasma, such as thermal instability and adsorption, compounds were silylated before gas chromatography. In order to increase the specificity of the assay, two specific ions of the isosorbide 5-monitrate were simultaneously recorded. The accuracy of the assay was tested day to day with quality specimens spiked blind to the analyst.