Desmosterol

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Desmosterol
Skeletal formula of desmosterol
Ball-and-stick model of the desmosterol molecule
Names
IUPAC name
Cholesta-5,24-dien-3β-ol
Systematic IUPAC name
(1R,3aS,3bS,7S,9aR,9bS,11aR)-9a,11a-Dimethyl-1-[(2R)-6-methylhept-5-en-2-yl]-2,3,3a,3b,4,6,7,8,9,9a,9b,10,11,11a-tetradecahydro-1H-cyclopenta[a]phenanthren-7-ol
Identifiers
3D model (
JSmol
)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.005.671 Edit this at Wikidata
IUPHAR/BPS
UNII
  • InChI=1S/C27H44O/c1-18(2)7-6-8-19(3)23-11-12-24-22-10-9-20-17-21(28)13-15-26(20,4)25(22)14-16-27(23,24)5/h7,9,19,21-25,28H,6,8,10-17H2,1-5H3/t19-,21+,22+,23-,24+,25+,26+,27-/m1/s1 checkY
    Key: AVSXSVCZWQODGV-DPAQBDIFSA-N checkY
  • InChI=1/C27H44O/c1-18(2)7-6-8-19(3)23-11-12-24-22-10-9-20-17-21(28)13-15-26(20,4)25(22)14-16-27(23,24)5/h7,9,19,21-25,28H,6,8,10-17H2,1-5H3/t19-,21+,22+,23-,24+,25+,26+,27-/m1/s1
    Key: AVSXSVCZWQODGV-DPAQBDIFBV
  • O[C@@H]4C/C3=C/C[C@@H]1[C@H](CC[C@]2([C@H]1CC[C@@H]2[C@H](C)CC\C=C(/C)C)C)[C@@]3(C)CC4
Properties
C27H44O
Molar mass 384.64 g/mol
Appearance White powder
Melting point 121.5 °C (250.7 °F; 394.6 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Desmosterol (Cholesta-5,24-dien-3β-ol) is a lipid present in the membrane of phytoplankton and an intermediate product in cholesterol synthesis in mammal cells.[1] Structurally, desmosterol has a similar backbone to cholesterol, with the exception of an additional double bond in the structure of desmosterol.

The similarity can be seen biologically through the synthesis of cholesterol in the human body, as desmosterol is the immediate precursor to cholesterol in the Bloch pathway.[2] Desmosterol is accumulated in desmosterolosis and undergoes reduction with the catalyst 24-dehydrocholesterol reductase to form cholesterol.[3]

In 2014, desmosterol was named the

ISMCBBPR).[4]

Structure of cholesterol and its immediate precursor, desmosterol.

Background

Desmosterol is classified as a cholestadienol, a subgroup of a wider known group of sterols, which naturally occur in eukaryotes. The presence of desmosterol in oceans and lakes has the potential to diagnose anoxic conditions and to study trends in steroid chemistry during the early stages of diagenesis.[5] Desmosterol has been found in high yields in samples of Rhizosolenia setigera (Brightwell) in Western Svalbard,[6] and from surface sediment off of the Peruvian Shelf sediment-water interface.[5]

In 1955, desmosterol was first described and isolated from chick embryo sterol with a 2% yield and was postulated as being a biological precursor to cholesterol by Stokes et al.

homarus americanus and pandalus borealis species. This strengthens the conclusion that desmosterol must be created exogenously, as crustaceans have not been seen to biosynthesise sterols.[9]

Biological occurrence

Desmosterol has been largely found within a large population of marine invertebrates. Major sources include

Laurencia pinnatifida, Polusiphonia nigrescens, Porphyra purpurea, and Dulse (Rhodymenia palmata)
after previously having been undetected.

In the 1968 paper by Idler, Saito and Wiseman,[10] dulse samples were analysed and the sterols present were determined by gas liquid chromatography. Samples were collected near Grand Manan Island, New York in 1964 and 1965, and showed a significant difference in the presence of desmosterol. Samples 1 and 2 were from the same source, as were samples 3 and 4, and all samples were harvested at different times. Samples 2, 3, and 4 had the major sterol as desmosterol, compared to sample 1, with the major sterol being cholesterol.[10] This indicates a 70% difference in desmosterol composition in the sterol samples (1 and 2) over a period of one year. There has been no conclusive evidence to show whether seasonal variation of sterols in barnacles occur.

Sterol composition of dulse samples from Grand Manan Island, New York, with data taken from Idler's 1968 paper.[10]

Biosynthesis

There are two major pathways for cholesterol biosynthesis, being the Kandutsch-Russell and Bloch pathways.[13] The Bloch pathway, named after Konrad Bloch, occurs naturally alongside the mevalonate pathway in humans within the cell. The discovery of this pathway led Bloch, joint with Feodor Lynen, to receive a Nobel Prize in Physiology or Medicine in 1964. The award was awarded “for their discoveries concerning the mechanism and regulation of the cholesterol and fatty acid metabolism”.[14]

Synthetic pathway from desmosterol to cholesterol

Preservation

Desmosterol has been seen to be present in

preservation potential
.

Use as a Biomarker

As a biomarker, desmosterol is important for the Chaetoceros calcitrans[16] and R. setigera and N. closterium[17] diatoms as well as Rhodophyceae.[18] However, desmosterol has the potential to be used as a taxonomic marker for diatoms where it exists as the dominant sterol, such as in Rhizosolenia.[17]

Balsfjorden, Northern Norway

Desmosterol has been used as a biomarker for the presence of copepods. The phytoplankton bloom of P. pouchetii and Thalassiosira decipiens resulted in low amounts of desmosterol at maximum chlorophyll levels, indicating the low abundance and efficient removal of copepods in these phytoplankton.[19]

Biomarker patterns at maximum chlorophyll in Balsfjorden. (1) 24-norcholesta-5,22E-dien-3β-ol, (2) 27-nor-24-methylcholesta-5,22E-dien-3β-ol, (3) cholesterol-5,22E-dien-3β-ol, (4) cholesterol-5-en-3β-ol, (5) 24-methylcholesta-5,22E-dien-3β-ol, (6) cholesterol-5,24-dien-3β-ol, (7) 24-methylcholesta-5,24(28)-dien-3β-ol, (8) 24-ethylcholesta-5,24(28)dien-3β-ol

Peruvian Shelf

Diatoms and Silicoflagellates are classes of phytoplankton present in sedimentary material from the sediment water interface in the Peruvian Shelf region.[5] Mineralogical analysis of this sedimentary material suggested large volumes of phytoplankton. Researchers at the University of Bristol examined the sterol composition of these sedimentary rocks which have gone through oxygen depletion, leading to anoxic conditions. These conditions have enhanced the preservation of lipids present during the time of formation, around 1 year prior, and have limited the degradation of these compounds.

Measurement techniques

Desmosterol has seen to be identified most commonly through chemical constants, ozonolysis, infrared spectroscopy, NMR, and mass spectrometry techniques.[10] The use of thin-layer and gas-liquid chromatography to measure desmosterol is less common with the development of more advanced techniques.

Mass Spectra of Desmosterol, with data from NIST Standard Reference Database 69: NIST Chemistry WebBook [20]

GC-MS

Samples from water sources are first extracted and partially purified before analysis. Sterols are commonly first derivatised after purification. Lipid extracts can be separated into their fragments by ionisation using Gas Chromatography followed by Mass Spectroscopy analysis. Desmosterol has a characteristic m/z peak at 384, as seen in the mass spectra.[6]

Ozonolysis

Desmosterol has been identified through ozonolysis of the sample, with the ozonolysis product of desmosterol having a melting point of 128 °C, and an Rf value of 0.31 with paper-chromatography with n-hexane and N,N-dimethyl formamide. The ozonolysis product also has ratios C: 45.68; H: 4.45; N: 23.21.[10]

See also

References

  1. doi:10.1016/j.colsurfa.2023.131489
    .
  2. PMID 5319508
    .
  3. PMID 23093550
    .
  4. ^ "Announcing ISMCBBPR's Molecule of the Year 2012". Archived from the original on 2015-09-24. Retrieved 2014-02-22.
  5. ^ a b c Smith, D.J.; Eglinton, G.; Morris, R.J.; Poutanen, E.L. (1983). "Aspects of the steroid geochemistry of an interfacial sediment from the Peruvian upwelling" (PDF). Oceanologica Acta. 6 (2): 211–219.
  6. ^
    hdl:10026.1/9642
    .
  7. PMID 13319360
    .
  8. ^
    doi:10.1021/ja01581a030
    .
  9. ^ Gagosian, Robert (1974). Summary of Investigations Conducted in 1974. Massachusetts: Woods Hole Oceanographic Institution. pp. C-16.
  10. ^
    PMID 5643148
    .
  11. doi:10.1248/cpb.21.323
    .
  12. doi:10.1016/0020-711X(71)90021-8
    .
  13. PMID 23554937
    .
  14. ^ "The Nobel Prize in Physiology or Medicine 1964". NobelPrize.org. Retrieved 2023-05-21.
  15. bioRxiv 10.1101/2022.05.16.491679
    .
  16. doi:10.1016/0010-406x(63)90020-3
    .
  17. ^
    S2CID 84292971
    .
  18. doi:10.1017/s0033291700021735
    .
  19. JSTOR 24863836
    .
  20. ^ "Desmosterol". webbook.nist.gov. 17 October 2019. Retrieved 2023-06-10.
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