A novel flavanone from Thymus przewalskii / 中国中药杂志

This study was to investigate the chemical constituents from the aerial parts of Thymus przewalskii. The chemical consti-tuents were separated and purified by column chromatography on silica gel, ODS, Sephadex LH-20 and semi-prepared HPLC, and their structures were determined by physicochemical properties and spectroscopic data. Four flavanones were isolated from the ethanol extract of the aerial parts of T. przewalskii, and identified as(2S)-5,6-dihydroxy-7,8,4'-trimethoxyflavanone(1), 5,4'-dihydroxy-6,7-dimethoxyflavanone(2),(2S)-5,4'-dihydroxy-7,8-dimethoxyflavanone(3), sakuranetin(4), respectively. Compound 1 was a new compound and its configuration was determined by CD spectrum, compound 3 was natural product which was isolated for the first time and their configurations were determined by CD spectra. Compound 2 was isolated from the genus Thymus for the first time and compound 4 was isolated from T. przewalskii for the first time. Furthermore, cytotoxicity test was assayed for the four flavanones. They exhibited weak cytotoxicity against human lung cancer cells(A549), with the IC_(50) from 74.5 to 135.6 μmol·L~(-1).

Determination of impurity diketo aldehyde in bulk drug and preparations of dihydroartemisinin / 中国中药杂志

Diketo aldehyde (DKA),one of the most important impurities in dihydroartemisinin,was synthesized through reaction between dihydroartemisinin and anhydrous ferrous bromide under a N₂ atmosphere, and an HPLC method was established for the determination of DKA in bulk drug and in DHA tablet. DKA was prepared from dihydroartemisinin in the presence of FeBr₂.The chromatographic separation was achieved through an Agilent Eclise XDB-C₁₈ column (4.6 mm×250 mm,5 μm), and the optimal mobile phase consisted of acetonitrile and water in the ratio of 37:63 at flow rate of 1.0 mL·min⁻¹.The detection was carried out at 216 nm, and column temperature was 15 °C.The injection volume was 40 μL.The method featured a good linearity (=0.999 9),precision (1.0%),repeatability (1.3%),stability (DKA standards RSD=1.0% and in tablet form instability),recovery (92.88%),limits of detection (0.20 mg·L⁻¹) ,and limits of quantification (0.78 mg·L⁻¹). The result show that the content of DKA in bulk drug was 0.086 7%-2.622 9%, and the content of DKA in tablet was 0.068 3%-0.615 1%.