Chromatographic separation of putative precursors of cholestanol
This paper describes convenient syntheses for labeled and unlabeled cholest-5-en-3-one, cholest-4-en-3-one, epicholesterol, cholest-4-en-3 beta-ol, and cholest-4-en-3 alpha-ol. The thin-layer chromatography, high-performance liquid chromatography, and gas-liquid chromatography of these compounds and of cholestanol and epicholestanol are also described. The synthesized compounds are potential precursors in the biosynthesis of cholestanol in mammals.
Comparative investigation on sterols from some Black Sea red algae
The sterol composition of five Black Sea red algae: Callithamnion granulatum, Ceramium rubrum, Ceramium elegans, Laurencia papillosa and Laurencia coronopus was obtained. Monohydroxy sterols and their oxidized derivatives have been identified. The results obtained were compared with some recent data for the composition of sterols in other Black Sea red algae, which occupy different evolutionary positions. On the basis of their composition, some conclusions about the chemotaxonomy and chemoevolution of the species investigated have been proposed.
HPLC determination of chlorhexidine gluconate and p-chloroaniline in topical ointment.
A novel fast isocratic reversed-phase HPLC method for simultaneous determination of chlorhexidine and its degradation product p-chloroaniline was developed. Zorbax SB Phenyl column (75 mm x 4.6 mm, 3.5 microm) was used for the separation. Mobile phase composed of acetonitrile and buffer solution of 0.08 M sodium phosphate monobasic containing 5 ml of triethylamine (0.5%) and adjust with 85% phosphoric acid to pH 3.0 in ratio 35:65 (v/v) pumped isocratically at flow rate 0.6 ml min(-1) was used. UV detection was performed at 239 nm, the total analysis time was about 10 min. The method is suitable for practical routine analysis of topical ointment in the quality control laboratory.