The isolation of cholest-5-ene-3beta,26-diol from human brain.
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ABSTRACT:
SUBMITTER: Smith AG
PROVIDER: S-EPMC1166347 | biostudies-other | 1974 Jun
REPOSITORIES: biostudies-other
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Project description:THE STRUCTURE OF THE TITLE STEROID [ALTERNATIVE NAME: 3β,6β-diacet-oxy-5β-methyl-19-norcholest-9(10)-ene], C31H50O4, confirms the generally accepted mechanism for the rearrangement of a cholestan-5α-ol derivative reported a century ago by Westphalen. The methyl group at position 10 of the starting material migrates to position 5 in the steroidal nucleus, while a Δ(9) bond is formed, as indicated by the C=C bond length of 1.347 (4) Å. The methyl transposition leaves the 5R configuration unchanged, with the methyl oriented towards the β face. During the rearrangement, the steroidal B ring experiences a conformational distortion from chair to envelope with the C atom at position 6 as the flap. In the title structure, the isopropyl group of the side chain is disordered over two positions, with occupancies of 0.733 (10) and 0.267 (10). The carbonyl O atom in the acetyl group at C3 is also disordered with an occupancy ratio of 0.62 (4):0.38 (4).
| S-EPMC3588934 | biostudies-literature
Project description:The asymmetric unit of the title compound, C(27)H(46), contains two crytallographically independent cholest-5-ene mol-ecules (A and B). In each mol-ecule, the three six-membered rings are all in chair conformations, while the five-membered ring is in a twist conformation. The terminal isopropyl group of mol-ecule A has a (-)-gauche conformation, whereas that of mol-ecule B has a (+)-gauche conformation. No significant inter-molecular inter-actions are observed in the crystal structure.
| S-EPMC3120455 | biostudies-literature
Project description:The title steroid, C(29)H(46)O(4), is a furostene derivative with a C=C double-bond length of 1.353?(3)?Å and an E configuration. The side chain is oriented toward the ? face of the A-E steroidal nucleus and presents a disordered terminal CH(2)-OH group [occupancies for resolved sites are 0.591?(9) and 0.409?(9)]. The methyl group at C20 attached to ring E is also oriented toward the ? face, avoiding steric hindrance with the carbonyl O atom of the acetyl group. The furostene and acetyl functionalities form an ?,?-unsaturated ketone system, with an s-cis configuration. All hydr-oxy and carbonyl groups are involved in weak inter-molecular hydrogen bonds. The absolute configuration was assigned from the synthesis.
| S-EPMC2960791 | biostudies-literature
Project description:1. When [(14)C]cholesterol was incubated with rat liver mitochondria, radioactive 26-hydroxycholesterol, 3beta-hydroxychol-5-enoic acid and other bile acids were isolated from the incubation mixture. 2. In the absence of added 26-hydroxycholesterol, the specific radioactivity of the 26-hydroxycholesterol formed from [(14)C]cholesterol during the incubation was higher than that of the 3beta-hydroxychol-5-enoic acid. Addition of increasing amounts of 26-hydroxycholesterol led to a progressive fall in the specific radioactivity, and to a progressive increase in the mass, of the 3beta-hydroxychol-5-enoic acid recovered at the end of the incubation. 3. It is concluded that 26-hydroxycholesterol is an intermediate in the formation of 3beta-hydroxychol-5-enoic acid from cholesterol. 4. Comparison of the specific radioactivity of the 26-hydroxycholesterol formed in the incubation mixture with that of the added [(14)C]cholesterol indicates that endogenous cholesterol in mitochondria is accessible to cholesterol 26-hydroxylase.
| S-EPMC1174415 | biostudies-other
Project description:Cyclo-art-24-ene-3?,26-diol, C(30)H(50)O(2), isolated from the leaves of Aglaia exima, has three six-membered rings fused together that adopt chair conformations. There are two independent mol-ecules in the asymmetric unit. O-H?O hydrogen bond inter-actions between the hydroxyl groups in the 3? and 26 positions lead to the formation of a layer structure parallel to (10).
| S-EPMC3007388 | biostudies-literature
Project description:In the title cholestane derivative, C(28)H(48) [systematic name: (1S,2S,7R,10R,11R,14R,15R)-2,5,10,15-tetra-methyl-14-[(2R)-6-methyl-heptan-2-yl]tetra-cyclo-[8.7.0.0(2,7).0(11,15)]hepta-dec-4-ene], the cyclo-hexene ring adopts a half-chair conformation. The parent 5α-cholest-2-ene and the equivalent fragment of the title compound are almost superimposable (r.m.s. deviation = 0.033 Å).
| S-EPMC3008105 | biostudies-literature
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
Project description:The title compound, C(27)H(45)Cl, is a second monoclinic polymorph which crystallizes in the space group P2(1) with four crystallographically independent mol-ecules in the asymmetric unit. The structure was previously reported [Bernal et al. (1940 ?). Philos. Trans. R. Soc. London Ser. B, 239, 135-182; Vani & Vijayan (1979 ?). Mol. Cryst. Liq. Cryst.51, 253-264], also in the space group P2(1), but with two unique mol-ecules in the asymmetric unit. As in the previously reported structures, rings A and C in the mol-ecule adopt chair conformations with half-chair conformations for rings B and D. The ring junctions B-C and C-D are trans, whereas the junction A-B is quasi-trans. In the crystal structure, mol-ecules are arranged in a head-to-tail fashion along a and are stacked along the b axis.
| S-EPMC2979588 | biostudies-literature
Project description:The title compound, C26H42ClNO2, is a 3?-chloro steroid with a Weinreb amide at the C-24 position. The two cyclo-hexane and the cyclo-hexene rings adopt chair and boat conformations, respectively. The cyclo-pentane ring has an envelope conformation.
| S-EPMC3589044 | biostudies-literature
Project description:The title compound {systematic name: (S)-1-[(2S,4aR,8aR)-2,4b,8,8-tetra-methyl-2,3,4,4a,4b,5,6,7,8,8a,9,10-dodeca-hydro-phenanthren-2-yl]ethane-1,2-diol}, C(20)H(34)O(2), is an ent-pimarane diterpenoid which was isolated from the stem bark of Ceriops tagal. In the asymmetric unit, there are two crystallographically independent mol-ecules, which are conformationally almost identical. In each mol-ecule, the two cyclo-hexane rings of the fused three-ring system adopt chair conformations, while the cyclo-hexene ring is in an envelope conformation, with the methylene C atom next to the side chain as the flap atom. In the crystal, mol-ecules are stacked in columns along the b axis through O-H?O hydrogen bonds.
| S-EPMC3275262 | biostudies-literature