Isolation and characterization of cholesterol-5B,6B-oxide from an aerated aqueous dispersion of cholesterol

An unknown autoxidation product in an aerated cholesterol sol was isolated by preparative thin layer chromatography. This compound was identified as cholesterol-5β,6β-oxide by gas liquid chromatography along with infrared and mass spectrometry.     

Synthesis,purification and characterization of 7-ketocholesterol and epimeric 7-hydroxycholesterols

Various methods were assessed for the synthesis of 7-ketocholesterol and epimeric 7-hydroxycholesterols. Upon the oxidation of cholesteryl acetate with t-butyl chromate, the resulting ketosterol acetate crystallized from methanol consisted of about 25% unoxidized cholesteryl acetate. After the sterol acetates were hydrolyzed in an aqueous K₂CO₃ medium, preparative TLC was used to fractionate the ketone from cholesterol. Of all the reducing agents employed, only LiAlH₄ reduced completely the purified 7-ketocholesterol to 7-hydroxycholesterols without side reaction products and ketone contamination. Yields of 21.3 mg of 7α-hydroxycholesterol and 72.6 mg of 7β-hydroxycholesterol were obtained by preparative TLC of a diol mixture prepared by the LiAlH₄-reduction of 100 mg of 7-ketocholesterol. To accomplish the preparative TLC separation of diol bands without overlapping, a double development of a chromatoplate with ethyl ether-cyclohexane (90∶10, v/v) and ethyl ether was essential. Data on the melting point, optical rotation and infrared spectra, as well as TLC and GLC characteristics, were obtained for purified 7-ketocholesterol and epimeric 7-hydroxycholesterols.     

Electrochemical sterilization of beer

Electrochemical inactivation of microorganisms was not achieved in beer but was achieved in physiological saline. Addition of carbohydrates or proteins to physiological saline prevented inactivation in this medium.     

GAS CHROMATOGRAPHY AND GAS CHROMATOGRAPHY-MASS SPECTROMETRY OF SOFT RESINS AND RELATED COMPOUNDS

The α-acids, β-acids, iso-α-acids, hulupones and humulinic acid have been separated by gas chromatography utilising the cool on-column injection technique on various bonded phase capillary columns. The α-acids were separated into cohumulone and humulone; the β-acids into colupulone and lupulone; and the hulupones into cohulupone and hulupone. Iso-α-acids were separated into four peaks; cis-isocohumulone, trans-isocohumulone, cis-isohumulone and trans-isohumulone. Flame ionization detection (FID) and chemical ionization mass spectrometry (CIMS) were used for chromatographic detection. Best results were achieved by employing a DB-1 fused silica capillary column with isooctane as the sample solvent .