Article

Sterol metabolism-XXX. Cholesterol 25-hydroperoxide metabolism

Biochemistry Laboratories, Department of Nuclear Medicine and Radiobiology, Centre Hospitalier Universitaire, Sherbrooke, Quebec, Canada
Journal of Steroid Biochemistry 11/1974; 5(6):581-6. DOI: 10.1016/0022-4731(74)90109-5
Source: PubMed

ABSTRACT

The metabolism of cholesterol 25-hydroperoxide by subcellular fractions of rat and calf liver and of rat kidney was examined. The sole metabolic transformation observed was the reduction of the 25-hydroperoxide to the corresponding 25-alcohol 5-cholestene-3β,25-diol. No evidence of enzymic rearrangement of the 25-hydroperoxide to vicinal diol products was adduced. Neither cholesterol 25-hydroperoxide nor 5-cholestene-3β,25-diol was converted by rat liver homogenates to bile acids. Attempts to demonstrate cholesterol 25-hydroperoxide as a putative intermediate in the biosynthesis of bile acids from cholesterol in rat liver homogenates and calf liver microsomes by trapping techniques were unsuccessful. It was concluded that cholesterol 25-hydroperoxide is not implicated in cholesterol metabolism in liver or kidney tissues.

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    • "La reducción de ambos isómeros determina la síntesis de 7α-y 7β-hidroxicoles- terol, mientras que su deshidratación induce la aparición de la forma 7-ketocolesterol (Teng et al., 1973). Asimismo, éste último puede surgir tras la descomposición hacia sus respectivos alcoholes de los isómeros 7α-y 7β-hidroxicoles- terol y posterior deshidratación (Teng et al., 1973a 1973b; Smith 1987; Nielson et al., 1996). En consecuencia, estos tres compuestos derivados del anillo B han sido identificados como los oxisteroles mayoritarios en distintos tipos de carne y productos cárnicos (Zubillaga y Maerker 1991; Gil 2002; Cayuela 2003). "

    Full-text · Article · Jan 2004
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    ABSTRACT: The oxidation of cholesterol by plant and mammalian dioxygenases yielding cholesterol 7α- and 7β-hydroperoxides has been demonstrated. Cholesterol oxidation is coupled to the oxygenation of polyunsaturated fatty acid esters by soybean lipoxygenase, to the reduction of hydrogen peroxide catalyzed by horseradish peroxidase, and to the oxidation of NADPH by the NADPH-dependent microsomal lipid peroxidation system of rat liver. The initially formed epimeric cholesterol 7-hydroperoxides are transformed in each case to the commonly encountered corresponding 7-alcohol and 7-ketone derivatives. These dioxygenase transformations thus mimic in detail the radiation-induced free radical oxidation of cholesterol by molecular oxygen. Electronically excited (singlet) molecular oxygen is not implicated in these transformations.
    No preview · Article · Mar 1976
  • [Show abstract] [Hide abstract]
    ABSTRACT: The oxidation of cholesterol by plant and mammalian dioxygenases yielding cholesterol 7α- and 7β-hydroperoxides has been demonstrated. Cholesterol oxidation is coupled to the oxygenation of polyunsaturated fatty acid esters by soybean lipoxygenase, to the reduction of hydrogen peroxide catalyzed by horseradish peroxidase, and to the oxidation of NADPH by the NADPH-dependent microsomal lipid peroxidation system of rat liver. The initially formed epimeric cholesterol 7-hydroperoxides are transformed in each case to the commonly encountered corresponding 7-alcohol and 7-ketone derivatives. These dioxygenase transformations thus mimic in detail the radiation-induced free radical oxidation of cholesterol by molecular oxygen. Electronically excited (singlet) molecular oxygen is not implicated in these transformations.
    No preview · Article · Mar 1976 · Bioorganic Chemistry
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