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Mode of formulation of cholesta-5,7-dien-3beta-ol from Cholest-5-en-3beta-ol by Larvae of Calliphora erythrocephala.

ABSTRACT: 1. The conversion of cholest-5-en-3beta-ol (cholesterol) into cholesta-5,7-dien-3beta-ol by axenic Calliphora erythrocephala larvae was demonstrated. 2. The transformation is probably direct (Delta(5)-->Delta(5,7)) and does not involve a Delta(0) intermediate (Delta(5)-->Delta(0)-->Delta(7)--> Delta(5,7)). 3. Delta(7)-bond formation involves the stereospecific elimination of the 7beta hydrogen atom. 4. The relative amounts of free and esterified sterols were determined in larvae grown on cholesterol as sole sterol source and on 5alpha-cholestan-3beta-ol supplemented with minimal amounts of cholesterol. 5. The significance of the results is assessed in relation to the probable role of cholesta-5,7-dien-3beta-ol as an intermediate in the biosynthesis of ecdysones.

SUBMITTER: Johnson P

PROVIDER: S-EPMC1172472 | biostudies-other | 1975 Nov

REPOSITORIES: biostudies-other

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The conversion of cholest-5-en-3beta-ol into cholest-7-en-3beta-ol by the echinoderms Asterias rubens and Solaster papposus.

Project description:1. The echinoderms Asterias rubens and Solaster papposus (Class Asteroidea) metabolize injected [4(-14)C]cholest-5-en-3beta-ol to produce labelled 5alpha-cholestan-3beta-ol and 5alpha-cholest-7-en-3beta-ol. 2. Conversion of 5alpha-[4(-14)C]cholestan-3beta-ol into 5alpha-cholest-7-en-3beta-ol was demonstrated in A. Rubens. 3. Incubations of A. rubens with [4(-14)C]cholest-4-en-3-one resulted in the production of labelled 5alpha-cholestan-3-one, 5alpha-cholestan-3beta-ol and 5alpha-cholest-7-en-3beta-ol. 4. [4(-14)C]Sitosterol was metabolized by A. rubens to give 5alpha-stigmastan-3beta-ol and 5alpha-stigmast-7-en-3beta-ol. 5. The significance of these results in relation to the presence of alpha7 sterols in starfish is discussed.

| S-EPMC1165273 | biostudies-other

A novel olefinic rearrangement. The enzymic conversion of cholesta-7,9-dien-3 -ol into cholesta-8,14-dien-3 -ol.

Project description:1. [3alpha-(3)H]Cholesta-7,9-dien-3beta-ol is converted in high yield into cholesterol by a 10000g(av.) supernatant fraction of rat liver homogenate. 2. Incubation of cholesta-7,9-dien-3beta-ol with [4-(3)H]NADPH and rat liver microsomal fractions under anaerobic conditions resulted in (3)H being incorporated into the 14alpha-position of cholest-7-en-3beta-ol. 3. Under anaerobic conditions in the absence of NADPH cholesta-7,9-dien-3beta-ol was isomerized into cholesta-8,14-dien-3beta-ol by rat liver microsomal fractions.

| S-EPMC1174072 | biostudies-other

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

Project description: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.

| S-EPMC1187605 | biostudies-other

The conversion of cholest-7-en-3beta-ol into cholesterol. General comments on the mechanism of the introduction of double bonds in enzymic reactions.

Project description:Convenient syntheses of 6beta-tritiated Delta(7)-cholestenol and 3alpha-tritiated Delta(7)-cholestene-3beta,5alpha-diol are described. It was shown that the conversion of 6beta-tritiated Delta(7)-cholestenol into cholesterol is accompanied by the complete retention of label. It was unambiguously established that the overall reaction leading to the introduction of the double bond in the 5,6-position in cholesterol occurs via a cis-elimination involving the 5alpha- and 6alpha-hydrogen atoms and that during this process the 6beta-hydrogen atom remains completely undisturbed. Metabolic studies with 3alpha-tritiated Delta(7)-cholestene-3beta,5alpha-diol revealed that under anaerobic conditions the compound is not converted into cholesterol. This observation, coupled with the previous work of Slaytor & Bloch (1965), is interpreted to exclude a hydroxylation-dehydration mechanism for the origin of the 5,6-double bond in cholesterol. It was also shown that under aerobic conditions 3alpha-tritiated Delta(7)-cholestene-3beta,5alpha-diol is efficiently converted into cholesterol and that this conversion occurs through the intermediacy of 7-dehydrocholesterol. Cumulative experimental evidence presented in this paper and elsewhere is used to suggest that the 5,6-double bond in cholesterol originates through an oxygen-dependent dehydrogenation process and a hypothetical mechanism for this and related reactions is outlined.

| S-EPMC1198440 | biostudies-other

5,7-Dichloro-quinolin-8-ol.

Project description:The mol-ecule of the title compound, C(9)H(5)Cl(2)NO, is essentially planar [give maximum or r.m.s. deviation] and the hydr-oxy group acts as a hydrogen-bond donor to the N atom of a symmetry-related mol-ecule, generating a hydrogen-bonded dimer,which lies on a twofold rotation axis.

| S-EPMC2977804 | biostudies-literature

Cholest-5-en-7-one.

Project description:In the deca-hydro-phenanthrenone ring system of the title compound, C(27)H(44)O, the two cyclo-hexane rings adopt chair conformations, whereas the cyclo-hexene ring adopts an envelope conformation. The cyclo-pentane ring is twisted. In the crystal structure, mol-ecules are stacked along the a axis, but no significant inter-molecular inter-actions are observed.

| S-EPMC3007018 | biostudies-literature

3?-Chloro-cholest-5-en-7-one.

Project description:The title compound, C(27)H(43)ClO, is a steroid derivative composed of a saturated carbon fused-ring framework with an alkyl side chain. The A and C rings have chair conformations and the B and D rings assume half-chair conformations. The cholesterol side chain is fully extended with a gauche, trans conformation of the terminal methyl groups. In the crystal structure, the molecules are aligned in an antiparallel fashion, forming alternate layers. These layers are then linked via C-H?O hydrogen bonds, forming a three-dimensional network.

| S-EPMC2983643 | biostudies-literature

3-Benzyl-5,7-dimeth-oxy-chroman-4-ol.

Project description:In the crystal structure of the title compound, C(18)H(20)O(4), O-H⋯O hydrogen bonds connect the mol-ecules in parallel layers along the b axis.

| S-EPMC3052041 | biostudies-literature

Cholest-5-en-3?-yl N-phenyl-carbamate.

Project description:In the title compound, C(34)H(51)NO(2), the dihedral angle between the planes of the phenyl ring and the carbonyl group is 9.30?(2)°. No significant inter-molecular inter-actions are observed in the crystal structure. The C(5)H(11) fragment is disordered over two positions with site occupancies of 0.611?(6) and 0.389?(6).

| S-EPMC2972052 | biostudies-literature

A new steroidal 5,7-diene derivative, 3beta-hydroxyandrosta-5,7-diene-17beta-carboxylic acid, shows potent anti-proliferative activity.

Project description:The new steroidal 5,7-diene, 3beta-hydroxyandrosta-5,7-diene-17beta-carboxylic acid (17-COOH-7DA), was synthesized from 21-acetoxypregnenolone, with the oxidative cleavage of the side chain being dependent on the presence of oxygen. In human epidermal (HaCaT) keratinocytes, 17-COOH-7DA inhibited proliferation in a dose-dependent manner, starting at a dose as low as 10(-11) M. This inhibition was accompanied by decreased expression of epidermal growth factor receptor, bcl2 and cyclin E2 mRNAs and by increased expression of involucrin mRNA. Inhibition of proliferation was associated with slowing of the cell cycle in G1/G0 phases but not with cell death. 17-COOH-7DA was significantly more potent than pregnenolone, 17-COOH-pregnenolone, 17-COOCH(3)-7DA and calcitriol. 17-COOH-7DA also inhibited proliferation of normal human epidermal melanocytes and human and hamster melanoma lines, however, with lower potency than for keratinocytes. In normal human dermal fibroblasts 17-COOH-7DA stimulated proliferation in serum-free media but inhibited it in the presence of 5% serum. 17-COOH-7DA inhibited cell colony formation of human and hamster melanoma cells, and induced monocyte-like differentiation of human HL60 leukemia cells. Thus, the new steroidal 5,7-diene, 17-COOH-7DA, can serve as an inhibitor of proliferation of normal keratinocytes and normal and malignant melanocytes, as a condition-dependent regulator of fibroblast proliferation and a stimulator of leukemia cell differentiation.

| S-EPMC2846116 | biostudies-literature

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