Co-Authors:
Lozano, R., Department of Botany, University of Maryland, College Park, 20742, MD, United States
Lusby, W.R., Insect Physiology Laboratory, ARS, USDA, Bldg. 467, BARC-East, Beltsville, 20705, MD, United States
Chitwood, D.J., Insect Physiology Laboratory, ARS, USDA, Bldg. 467, BARC-East, Beltsville, 20705, MD, United States
Svoboda, J.A., Insect Physiology Laboratory, ARS, USDA, Bldg. 467, BARC-East, Beltsville, 20705, MD, United States
Abstract:
The metabolism of 4 dietary 24-alkylsterols was investigated in the free-living nematode Caenorhabditis elegans. The major unesterified sterols of C. elegans in media supplemented with either campesterol, 22-dihydrobrassicasterol or stigmasterol included cholesta-5,7-dienol, cholesterol, cholest-7-enol, and 4α-methylcholest-8(14)-enol. Dietary stigmastanol yielded cholest-7-enol, cholestanol, cholest-8(14)-enol, and 4α-methylcholest-8(14)-enol as major unesterified sterols. Esterified sterols comprised less than 22% of the total sterol. Removal of a C-24 ethyl substituent of sterols was neither hindered by the presence of a Δ22-bond in the sterol side chain nor was it depedent on unsaturation in ring B of the steroid nucleus. C. elegans reduced a Δ22-bond during its metabolism of stigmasterol; it did not introduce a Δ22-bond during stigmastanol metabolism. C. elegans was capable of removing a C-24 methyl substituent regardless of its stereochemical orientation. Metabolic processes involving the steroid ring system of cholesterol (C-7 dehydrogenation, Δ5-bond, 4α-methylation, Δ8(14)-isomerization in C. elegans were not hindered by the presence of a 24-methyl group; various 24-methylsterol metabolites from campesterol were detected, mostly 24-methylcholesta-5,7-dienol. In contrast, no 24-ethylsterol metabolites from the dietary ethylsterols were found. More dietary 24-methylsterol remained unmetabolized than did dietary 24-ethylsterol. A 24α-ethyl group and a 24β-methyl group were dealkylated to a greater extent by C. elegans than was a 24α-methyl group, perhaps reflecting the substrate specificity of the dealkylation enzyme system, or suggesting different enzymes altogether. © 1985 American Oil Chemists' Society.