Sterols affecting meiosis: novel chemical syntheses and the biological activity and spectral properties of the synthetic sterols

Abstract

4,4-Dimethyl-5 ␣ -cholesta-8,14,24-trien-3 ␤ -ol ( I ) from human follicular fluid and 4,4-dimethyl-5 ␣ -cholesta-8,24-dien-3 ␤ -ol ( II ) from bull testes have been reported to activate meiosis in mouse oocytes (Byskov et al., 1995. Nature. 374: 559-562). Described herein are new chemical syntheses of I, II , and the ⌬ 8(14),24 analog XXII . A critical step in these syntheses was a remarkably high yield side chain oxidation of 3 ␤ -acetoxy-4,4-dimethyl-5 ␣ -cholest-8(14)-en-15one to the corresponding C 24 24-hydroxy compound VI . Oxidation of VI to the aldehyde, followed by Wittig olefination gave 3 ␤ -acetoxy-4,4-dimethyl-5 ␣ -cholesta-8(14),24dien-15-one. Reduction with sodium borohydride to the 15 ␤ -hydroxysteryl ester, dehydration with sulfuric acid in CHCl 3 , and saponification furnished I in high purity. Reduction of VI with sodium borohydride to the 15-hydroxysteroid followed by dehydration gave 3 ␤ -acetoxy-4,4-dimethyl-5 ␣ -chola-8,14-dien-24-ol. Hydrogenation over Raney nickel gave the monounsaturated ⌬ 8(14) and ⌬ 8 compounds.Oxidation to the corresponding aldehydes followed by Wittig olefination and saponification gave II and XXII . Chromatographic, mass spectral, and 1 H and 13 C nuclear magnetic resonance spectral data have been presented for the synthetic sterols and their derivatives. I, II, XXII , and their ⌬ 8,14 and ⌬ 7,14 analogs, at 3 g per ml, caused a resumption of meiosis in mouse oocytes in the presence of hypoxanthine (3.5 m m ). Under the same conditions, ⌬ 5 and ⌬ 5,7 sterols were inactive. -

Processive kinetics in the three-step lanosterol 14α-demethylation reaction catalyzed by human cytochrome P450 51A1

“…The final enzymatic product FF-MAS ( Fig. 1 ) has been synthesized previously ( 28 , 29 ), but in our synthesis of 14α-oxygenated dihydrolanosterol derivatives ( Figs. 3 and S1 ), we found that a side product with strong UV absorbance was formed in the step involving BF 3 treatment of the 14,15-epoxide compound 8 ( Figs.…”

Oxysterols: Modulators of Cholesterol Metabolism and Other Processes

“…Furthermore, before testing in the biological assay systems, the sterols were sonicated in medium, a procedure likely to result in autoxidation of the various unsaturated sterols. The activation of meiosis by the 4,4-dimethyl-⌬ 8,14,24 sterol has now been demonstrated for the sterol prepared by chemical synthesis (351,871). Activation was also demonstrated for the synthetic 4,4-dimethyl-⌬ 8,24 sterol and 4,4-dimethyl-⌬ 8(14),24 sterol (871).…”

“…Whereas 4,4-dimethyl-5␣-cholesta-8,14,24-trien-3␤-ol was found to activate meiosis and to activate LXR␣ (351,441), several oxysterols with high potency in the activation of LXR␣ have been found to have no effect on meiosis in mouse oocytes (351,871). In one study, the oxysterols included (20R,22R)-20,22-diOH-Chol and (22R)-22-OH-Chol (871), both previously shown to have high potency in activating LXR␣ (309).…”

Production of Meiosis-Activating Sterols from Metabolically Engineered Yeast

“…T-MAS was identified by comparison of its 1 H NMR and mass spectra with those of an authentic standard and with published data. 2a,6a …”

“…These compounds are remarkably difficult to obtain, even in milligram amounts. Published syntheses of FF-MAS and T-MAS entail at least 12 steps from commercially available steroids and proceed in overall yields of well under 10% . A more efficient route described in the patent literature is also lengthy .…”