The role of a cholesta-8,14-dien-3β-ol system in cholesterol biosynthesis

Abstract

The biosynthesis of cholesterol from squalene and tritiated water is described. Degradation of the cholesterol indicated that C-15 may be involved in cholesterol biosynthesis. In accordance with this view it is shown that in the conversion of [2RS-(3)H(2)]mevalonic acid into cholesterol one of the hydrogen atoms at C-15 is removed. A mechanism for the removal of the 14alpha-methyl group in steroid biosynthesis that involves the labilization of a C-15 hydrogen atom is outlined. In accordance with the requirement of this scheme it is shown that 4,4'-dimethyl-cholesta-8,14-dien-3beta-ol is converted into cholesterol.

Fungitoxicity and growth regulation involving aspects of lipid biosynthesis

“…It has been postulated that a hydroxyl group must be inserted at C-15 in order to permit the final decarboxylation in the C-14 demethylation sequence (Akhtar et al, 1969). According to this scheme the C-15 hydroxyl would subsequently be eliminated and the resulting double bond reduced.…”

Metabolism of 2,4‐3H‐14α‐methyl‐5α‐ergost‐8‐enol and 2,4‐3H‐5α‐ergosta‐8,14‐dienol inChlorella ellipsoidea

“…With the exception of the pollinastanol work (1), potential sterol precursors, such as these, have not been shown to be converted to normally occurring sterols of plants. In this paper, we demonstrate the incorporation of [2,4-3H] -14ammethyl-5a-ergost-8-en-3/3-ol and [2,4] 3H]-5a-ergosta-8,14,-dien-3~-ol into ~s_ ergostenol in growing C eIIipsoidea cultures. ,1200 EXPERIMENTAL PROCEDURES A8,14_Ergostadienol (5 a-ergosta-8,14-dien-313-ol) and 14a-methyl A8-ergostenol (14amethyl-5a-ergost-8-en-3fl-ol) were synthesized chemically from ergosterol (10,1 l) and labeled with tritium at the C-2 and C-4 positions, as described by Thompson,et al (12).…”

“…The conversion of 14c~-methyl-9/3,19-cyclo-5c~-cholestan-3~-ol (pollinastanol) into cholesterol has been reported to occur in tobacco leaves (1). Cholesta-8,14-dien-3/~-ol has been demonstrated to be converted into cholesterol using enzymatic preparations from animal systems (2)(3)(4)(5)(6)(7). The accumulation of A8,14-sterols and 14c~methyl A8-sterols has been observed as a result of AY-9944 treatment and triparanol treatment, respectively, in Chlorella ellipsoidea (8,9).…”

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

“…For exploration of these interesting and potentially important matters, we have pursued the chemical syntheses of 4,4-dimethylsterols I and II. We (21) and others (30,31) have previously described the preparation of the 4,4dimethyl-⌬ 8,14 -sterol III. The syntheses of I and II represent more formidable challenges, requiring the introduction of the 4,4-dimethyl functionality, the provision of the ⌬ 8,14 and ⌬ 8 double bonds of I and II, respectively, and the introduction of the ⌬ 24 double bond.…”