The configuration of Δ5,7,22-sterols in a tracheophyte

Nes, William R.; Krevitz, Kenneth; Behzadan, Shamideh; Patterson, Glenn W.; Landrey, Josephine R.; Conner, Robert L.

doi:10.1016/0006-291x(75)90523-9

Cited by 23 publications

(4 citation statements)

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“…On the other hand, the 'H-NMR. analysis affords a secure assignment [18] and in the 360 MHz spectrum of the isolated 2c, methyl signals occur at: 0.629 (s, H3C (18) The third tri-unsaturated sterol of B. fortis was (22E, 24lR)-24-ethylcholesta-5,7,22-trien-38-01 (2e). This component, again without specification of the C (24) configuration, has been reported to occur in other sponges [14-161.…”

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Ergosta‐5,7,9(11), 22‐tetraen‐3β‐ol and its 24ξ‐Ethyl Homolog, Two New Marine Sterols from the Red Sea Sponge Biemna fortis

Delseth

Kashman

Djerassi

1979

Helvetica Chimica Acta

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The steroidal components of a Red Sea sponge, Biemna fortis, were fractionated through reversed phase HPLC. and analyzed by a combination of physical methods, including high resolution GC./MS. and 360 MHz 'H-NMR. The sponge contains five conventional d5-sterols, la-c, le, l g , which comprise about 25% of the mixture and 2,5% of gorgosterol (lh), a sterol never found before in Porifera. Three ~l~~~~~~-s t e r o l s were also present as major components in the mixture ( N 70%): cholesta-5,7,22-trien-3,f?-ol (Za), ergosta-5,7,22-trien-3/?-01 (2c) and (24R)-ethylcholesta-5,7,22-trien-3~-oI (2e) whereas two new tetra-unsaturated sterols were identified in minor amounts (2%): ergosta-5,7,9 (1 l), 22-tetraen-3P-01 (3c) and 24(-ethylcholesta-5,7,9 (1 l), 22-tetraen-3P-01 (3e or 3f). NMR. spectroscopy made possible the assignment of a 24R configuration for all the C(24) substituted sterols isolated in sufficient amount from the mixture. The possible symbiotic, dietary or biosynthetic origins of these sterols are discussed.Introduction. -Marine organisms such as sponges constitute a rich source of sterols possessing unusual side-chains or unconventional ring systems [2-61. Besides their chemical structure elucidation such sterols raise interesting questions in terms of biosynthesis and biological function [7]. Against this background and in our continuing search for key biosynthetic intermediates among the minor and trace components of marine sterol mixtures [ 11, we report the composition of the Red Sea sponge Biemna fortis.Results. -The gas-liquid chromatographic (GC.) and combined gas chromatographic-mass spectrometric (GCJMS.) analyses of the free sterol mixture allow the resolution of the number, the identity, and the amount of the components. These data are corroborated by the GC./MS. analysis on capillary columns of the trimethylsilyl ethers of the mixture. Further separations of the free sterols by high I) Part XIV in the Stanford series 'Minor and Trace Sterols in Marine Invertebrates'. Part XIII: [l].

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Ergosta‐5,7,9(11), 22‐tetraen‐3β‐ol and its 24ξ‐Ethyl Homolog, Two New Marine Sterols from the Red Sea Sponge Biemna fortis

Delseth

Kashman

Djerassi

1979

Helvetica Chimica Acta

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“…The configuration (which presumably influences function) is known to depend on taxonomy and apparently also on evolutionary status (2,(5)(6)(7)(8). Statistically a more frequent occurrence of 24,3-alkylsterols1 is observed the lower an organism is in the evolutionary hierarchy.…”

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“…That some sort of evolutionary process is reflected here is given credence by the sterols of the low tracheophyte, Lycopodium, which is intermediate between the lowest and highest of the photosynthetic plants. In L. complanatum one finds an unusually high amount of 24/3-alkylsterol in the form of 243-methylsterols with A5-and A5-"-types of nuclear unsaturation even though the 24-ethyl component is exclusively of the «-configuration (7,8). Consequently, in order to understand function and phylogenetics better, it is necessary to know unequivocally what the configuration at C-24 is in sterols derived from various taxonomic groups.…”

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“…Consequently, in order to understand function and phylogenetics better, it is necessary to know unequivocally what the configuration at C-24 is in sterols derived from various taxonomic groups. This was first achieved spectroscopically with 'H-nmr (6)(7)(8)(9)(10)(11)(12)(13). At a field strength of at least 220 MHz, one can distinguish C-24 epimers with particular clarity.…”

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Proof of Structure For 24β-Methylcholesterol in the Alga Coccomyxa elongata by ¹H- and ¹³C-nmr and Mass Spectroscopy

Nes¹,

Zarembo²

1981

J. Nat. Prod.

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The green alga Coccomyxa elongnta belonging to the order Chlorosphaerales (in the older literature Tetrasporales or Yolvocales) is known to contain a sterol mixture. An examination of the component in the largest amount by 1and 13C-nmr spectroscopy together witli mass spectral data rigorously proved it to be 243-methylcholesterol. In addition, our information indicated stereochemical purity. This alga, therefore, corresponds to the other green alga species investigated in that the 24-alkylsterols present have the 243-configuration.The chiral centers in sterols can be divided into those which are invariant and those which differ depending on the living systems in which they occur.Among the AYsterols, which appear to comprise the most common type, all of the chiral centers at ring junctions fall into the invariant category so far as is known (1, 2). Two centers in the side chain also appear to be invariant. Timare at C-20 and the point (C-17) where the side chain meets the tetracyclic system (1-4). Thus, it is possible to describe all naturally occurring A* *5 *7-sterols as having the stereochemistry of cholesterol at C-8, C-9. C-10, C-13, C-14. C-17, and C-20. However, when C-24 is rendered chiral by the introduction of an alkyl group, variance at this position occurs.

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The Biosynthesis of Ergosterol

Mercer

1984

Pestic. Sci.

116

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The present state of knowledge of ergosterol biosynthesis is reviewed briefly in order to provide a contextual framework for the following papers which deal with its inhibition, the compounds that cause this inhibition, and their mode of action. The paper concentrates upon the post‐squalene segment of the process as it occurs in fungi because the commercially important inhibitors of ergosterol biosynthesis are fungicides that block steps within that process.

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The configuration of Δ5,7,22-sterols in a tracheophyte

Cited by 23 publications

References 10 publications

Ergosta‐5,7,9(11), 22‐tetraen‐3β‐ol and its 24ξ‐Ethyl Homolog, Two New Marine Sterols from the Red Sea Sponge Biemna fortis

Ergosta‐5,7,9(11), 22‐tetraen‐3β‐ol and its 24ξ‐Ethyl Homolog, Two New Marine Sterols from the Red Sea Sponge Biemna fortis

Proof of Structure For 24β-Methylcholesterol in the Alga Coccomyxa elongata by ¹H- and ¹³C-nmr and Mass Spectroscopy

The Biosynthesis of Ergosterol

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The configuration of Δ5,7,22-sterols in a tracheophyte

Cited by 23 publications

References 10 publications

Ergosta‐5,7,9(11), 22‐tetraen‐3β‐ol and its 24ξ‐Ethyl Homolog, Two New Marine Sterols from the Red Sea Sponge Biemna fortis

Ergosta‐5,7,9(11), 22‐tetraen‐3β‐ol and its 24ξ‐Ethyl Homolog, Two New Marine Sterols from the Red Sea Sponge Biemna fortis

Proof of Structure For 24β-Methylcholesterol in the Alga Coccomyxa elongata by 1H- and 13C-nmr and Mass Spectroscopy

The Biosynthesis of Ergosterol

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Proof of Structure For 24β-Methylcholesterol in the Alga Coccomyxa elongata by ¹H- and ¹³C-nmr and Mass Spectroscopy