title: Concerning the role of 24,25-dihydrolanosterol and lanostanol in sterol biosynthesis by cultured cells.
abstract: Rat hepatoma cells (H4-II-E-C3) efficiently converted a dietary supplement of [2-3H]24,25-dihydrolanosterol (1) to [3H]cholesterol while [2-3H]lanostanol (4,4,14 alpha-trimethylcholestanol (2) was recovered from the cells without apparent transformation, although it was esterified and induced an accumulation of lanosterol. A comparison of the chromatographic (TLC, GLC and HPLC), spectral (MS and 1H-NMR) and physical properties of 1 and 2 is given for the first time. The inability to detect 2 in nature coupled with our findings that 1 but not 2 is metabolized to cholesterol by H4 cells is interpreted to imply that the biosynthetic inclusion of the delta 8(9)-bond during the cyclization process of squalene-oxide to a tetracyclic product is an evolutionary adaptation selected for because the olefinic linkage is structually important in the subsequent conversion of lanosterol and its stereoisomers, e.g., cycloartenol, to delta 5-sterols.
authors: Plant Physiology Research Unit, Russell Research Center, USDA, Athens, GA 30613.
authors: W D
authors: WD
authors: Nes
authors: R A
authors: RA
authors: Norton
authors: E J
authors: EJ
authors: Parish
authors: A
authors: A
authors: Meenan
authors: G
authors: G
authors: Popják
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D008401:Gas Chromatography-Mass Spectrometry; D007810:Lanosterol / Q000031:analogs & derivatives* / Q000378:metabolism*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D051381:Rats; D013261:Sterols / Q000378:metabolism*; D014316:Tritium; D014407:Tumor Cells, Cultured
chemical_list: D013261:Sterols; D014316:Tritium; D007810:Lanosterol; C015316:lanostenol