Microscale preparation of natural and labeled oxysterols.
The preparation of cholesterol and radiocholesterol oxidation products on a microscale is difficult. Cholesterol generally resists oxidation unless it is well dispersed under controlled conditions. A method was developed to reliably produce 7 alpha- and 7 beta-hydroxycholesterol and 7-ketocholesterol. Small changes in pH, metal ions present, or in the colloidal dispersion, resulted in production of completely different oxysterols. Attempts to oxidize aged radiocholesterol were not successful even after purification by several thin-layer chromatographic steps, and this appeared to be due to a time-related change in the radioactive material. Fresh radiocholesterol oxidized readily.
Krut
L H
LH
Metabolism Division, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Schonfeld
G
G
Ostlund
R E
RE
D002250:Carbon Radioisotopes; D002784:Cholesterol / Q000302:isolation & purification; D002855:Chromatography, Thin Layer / Q000379:methods; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006888:Hydroxycholesterols / Q000138:chemical synthesis* / Q000302:isolation & purification; D007553:Isotope Labeling / Q000379:methods; D007653:Ketocholesterols / Q000138:chemical synthesis* / Q000302:isolation & purification; D008832:Microchemistry / Q000379:methods; D015203:Reproducibility of Results; D012997:Solvents
D002250:Carbon Radioisotopes; D006888:Hydroxycholesterols; D007653:Ketocholesterols; D012997:Solvents; D002784:Cholesterol; C003001:7-ketocholesterol