Sterol metabolism. XX. Cholesterol 7.beta.-hydroperoxide

Abstract

Tetraacetate of ezo-Oxabicyclo[2.2.1!hept-5-ene-2,3-diol (8).-Oxabicy clo[2.2.1]-hept-5-ene-2,3-dioI carbonate (lb) (600 mg, 3.8 mmol) was dissolved in 15 ml of the ethyl acetate and 0.77 ml of dry pyridine; 1 g of osmium tetroxide dissolved in 2 ml of ethyl acetate was added. This mixture was sealed and left for 24 hr at room temperature. The solution was filtered, and a dry, black precipitate weighing 1.4 g was collected; 60 g of sodium sulfite (Na3S03), previously dissolved in 300 ml of water, and 300 ml of ethyl alcohol were added to the black precipitate. The mixture was boiled for 7 hr, producing a new, black precipitate, Nad0S(S03)3] • 20. This solution was concentrated, and its volume was reduced to 50 ml. Sodium hydroxide solution (5 ml), 5% (w/v) was added. This mixture was maintained at room temperature for 1 hr. Once again it was neutralized with acid, then concentrated to dryness, and dried at 60-80°for 4 hr.Acetylation of the Anhydro as-Inositol 8.-Acetic anhydride (50 ml) was added to the dry residue previously obtained. This mixture was warmed for 24 hr in an electric bath. Then the aceetic anhydride was removed in vacuo, and the residue resembled needles, mp 188-190°, yield 40 mg (6.6%), ir max 1750, 1250, 840, 820 cm-1.ept-Inositol (9,11).-A solution (5 ml) consisting of 80% (v/v) acetic acid, 20% (v/v) water, and 1% (v/v) sulfuric acid was added to 10 mg (0.061 mmol) of hydroxylated material 8. The mixture was warmed over a water bath for 14 hr, then tested by paper chromatography.19 20 One spot was revealed which corresponded to cpi-inositol, R¡ 0.20.® Also the Scherer reaction18 was positive. The dry residue was acetylated by adding 5 ml of acetic anhydride and a few drops of concentrated sulfuric acid. This mixture was left at 40°for 24 hr and poured into cold water, and then yielded crystals of 11. Further purification from toluene yielded crystals, mp 186-190°.7

Dietary vitamin E supplementation on cholesterol and cholesterol oxides of pig meat and cooked ham

“…7α-hydroxycholesterol, 7β-hydroxycholesterol and 7-ketocholesterol were not found in ham and cooked ham samples analyzed in the present work. This apparently contradicted the hypothesis of Teng et al (1973) that the first oxides formed by the cholesterol auto-oxidation were 7α, 7β-hydroxycholesterol and 7-ketocholesterol. Korahani et al (1982) suggested that the presence of fatty acid such as C18:0 and C18:1 inhibited the cholesterol oxidation.…”

Hydroperoxysterols from the Tunicate Eudistoma sp.

“…The hydroperoxysterols 1 and 2 had been prepared from cholesterol in 1973 15) and 1958, 16) respectively. The mechanism of the rearrangements of allylic hydroperoxides also have been proven.…”

“…The physical and spectral data of 1 are in full agreement with those reported previously. 15,19) 7a-Hydroperoxycholesterol (2): White amorphous powder, 1 H-and 13 C-NMR data, see Table 1. The physical and spectral data of 2 are in full agreement with those reported previously.…”

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“…There was also evidence for the presence of more polar compounds such as 7-hydroxy sterols, 5,6 -epoxides and A^^ -stigmasten -3,5,6 triol. Based on existing literature for cholesterol (Fioriti, 1967, Van Lier, 1970, Teng, 1973, Homberg, 1975, Smith, 1978. Blekas (1989) proposed a series of possible reactions for the formation of oxidation products of stigmasterol, both from rings A and B and the side chain.…”