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{{more cn|date=September 2022}} |
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{{Chembox |
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| verifiedrevid = 459129075 |
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| verifiedrevid = 459444041 |
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| Name = 18β-Oleanane |
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| Name = 18β-Oleanane |
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| ImageFile = Oleanane.svg |
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| ImageFile = Oleanane.svg |
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| ImageClass = skin-invert-image |
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| ImageSize = 200px |
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| ImageSize = 200px |
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| IUPACName = Oleanane<ref>{{cite book |author=] |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=] |pages=1538 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}</ref> |
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| IUPACName = Oleanane<ref></ref> |
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| SystematicName = (4a''R'',6a''R'',6b''R'',8a''S'',12a''S'',12b''R'',14a''R'',14b''S'')-2,2,4a,6a,6b,9,9,12a-Octamethyldocosahydropicene |
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| OtherNames = |
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| OtherNames = |
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| Section1 = {{Chembox Identifiers |
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| Section1 = {{Chembox Identifiers |
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| CASNo = <!-- blanked - oldvalue: 471-67-0 --> |
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| CASNo = 471-67-0 |
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| CASNo_Ref = {{cascite|correct|??}} |
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| CASNo_Ref = {{cascite|changed|??}} |
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| UNII_Ref = {{fdacite|correct|FDA}} |
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| ChEBI = 36481 |
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| UNII = CB9Y4447CP |
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| ChEBI_Ref = {{ebicite|correct|EBI}} |
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| ChEBI = 36481 |
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| PubChem = 9548717 |
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| PubChem = 9548717 |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |
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| ChemSpiderID = 7827640 |
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| ChemSpiderID = 7827640 |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| SMILES = 54((3(1((2(C)(CC1)C(C)(C)CCC2)CC3)C)(C)CC4)CC(C)(C)CC5)C |
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| StdInChI_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChI = 1S/C30H52/c1-25(2)16-17-27(5)18-19-29(7)21(22(27)20-25)10-11-24-28(6)14-9-13-26(3,4)23(28)12-15-30(24,29)8/h21-24H,9-20H2,1-8H3/t21-,22+,23+,24-,27-,28+,29-,30-/m1/s1 |
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| StdInChI = 1S/C30H52/c1-25(2)16-17-27(5)18-19-29(7)21(22(27)20-25)10-11-24-28(6)14-9-13-26(3,4)23(28)12-15-30(24,29)8/h21-24H,9-20H2,1-8H3/t21-,22+,23+,24-,27-,28+,29-,30-/m1/s1 |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} |
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| StdInChIKey = VCNKUCWWHVTTBY-KQCVGMHHSA-N |
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| StdInChIKey = VCNKUCWWHVTTBY-KQCVGMHHSA-N |
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| InChI = 1/C30H52/c1-25(2)16-17-27(5)18-19-29(7)21(22(27)20-25)10-11-24-28(6)14-9-13-26(3,4)23(28)12-15-30(24,29)8/h21-24H,9-20H2,1-8H3/t21-,22+,23+,24-,27-,28+,29-,30-/m1/s1 |
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| InChI = 1/C30H52/c1-25(2)16-17-27(5)18-19-29(7)21(22(27)20-25)10-11-24-28(6)14-9-13-26(3,4)23(28)12-15-30(24,29)8/h21-24H,9-20H2,1-8H3/t21-,22+,23+,24-,27-,28+,29-,30-/m1/s1 |
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| InChIKey = VCNKUCWWHVTTBY-KQCVGMHHBI |
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| InChIKey = VCNKUCWWHVTTBY-KQCVGMHHBI |
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}} |
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| Section2 = {{Chembox Properties |
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| Section2 = {{Chembox Properties |
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| C=30|H=52 |
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| C=30 | H=52 |
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| Section3 = {{Chembox Hazards |
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'''Oleanane''' is a natural ]. It is commonly found in woody angiosperms and as a result is often used as an indicator of these plants in the fossil record. It is a member of the oleanoid series, which consists of pentacyclic triterpenoids (such as beta-] and ]{{verify inline|date=September 2022}}) where all rings are six-membered. |
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'''Oleanane''' is a natural ]. It forms the central core for a wide variety of chemical compounds found in flowering plants which are referred to collectively as oleanane triterpenes. |
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==Structure== |
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Some oleanane triterpenes have a suppressing effect on insect ]. They are considered a key marker differentiating flowering plants from other life, and have been used in the effort to study their ], which is as of yet poorly documented in the fossil record. |
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Oleanane is a pentacyclic triterpenoid, a class of molecules made up of six connected isoprene units. The naming of both the ring structures and individual carbon atoms in oleanane is the same as in ]s. As such, it consists of a A, B, C, D, and E ring, all of which are six-membered rings.<ref name=":0">{{Cite web|url=https://sites.google.com/site/killopsiog/|title=killopsiog|website=sites.google.com|access-date=2019-05-15}}</ref>{{fv|date=September 2022}} |
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The structure of oleanane contains a number of different methyl groups, that vary in orientation between different oleananes. For example, in 18-alpha-oleanane contains a downward facing methyl group for the 18th carbon atom, while 18-beta-oleanane contains an upward facing methyl group at the same position. |
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These compounds appear to have been shared by a group of plants called ]s, which lived twice as long ago as the oldest known flower fossils.<ref>{{aut|Miller, John M.}} (2007): . Version of 2007-DEC-10. Retrieved 2007-DEC-12.</ref> They may have been close relatives of the flowering plants, moving the divergence of the flowering plant lineage back to more than 250 million years ago. |
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A and B rings of the oleanane structure are identical to that of ]. As a result, both molecules produce a fragment of m/z 191. Because this fragment is often used to identify hopanes, oleanane can be mis-identified in hopane analysis. |
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Oleanane has also been found in extant ferns, though in those it is suspected of being produced "from a biochemical pathway separate from that found in angiosperms" (via ]).<ref>{{cite journal | doi = 10.1666/0094-8373(2006)322.0.CO;2 | issn = 0094-8373 | year = 2006 | volume = 32 | pages = 179 | title = Biogeochemical evidence for the presence of the angiosperm molecular fossil oleanane in Paleozoic and Mesozoic non-angiospermous fossils | last1 = Taylor | first1 = David Winship | last2 = Li | first2 = Hongqi | last3 = Dahl | first3 = Jeremy | last4 = Fago | first4 = Fred J. | last5 = Zinniker | first5 = David | last6 = Moldowan | first6 = J. Michael | journal = Paleobiology | issue = 2}}</ref> |
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==Synthesis== |
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Like other triterpenoids, are formed from six combined isoprene units.<ref name=":0" /> These isoprene units can be combined via a number of different pathways. In eukaryotes (including plants), this pathway is the mevalonate (MVA) pathway. For the formation of steroids and other triterpenoids the isoprenoids are combined into a precursor known as squalene, which then undergoes enzymatic cyclization to produce the various different triterpenoids, including oleanane.<ref name=":0" /> |
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Once the oleananes have been transported into rocks or sediments they will undergo further alteration before they are measured. |
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== Measurement in Rock Samples == |
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Oleananes can be identified in extracts from rock samples (or plants) using GC/MS. A GC/MS is a gas chromatograph coupled with a mass spectrometer. The sample is first injected into the system, then run through as chromatographic column. How fast a material moves through a chromatographic column depends on how long it spends in each of the two stages there. Compounds that partition more into the mobile phase will move faster as opposed to compounds that partition more into the stationary phase. The result of this is a separation of different organic molecules based on their retention time in the GC. |
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After being separated by the GC, the compounds can then be analyzed by a mass spectrometer. Each compound will contain a characteristic mass spectrum, based on the fragments it splits into during ionization in the mass spectrometer. This means that the GC can not only separate different types of molecules, it can also identify them. |
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As mentioned above, they have a characteristic mass fragment at m/z = 191, and thus will appear in the same selected ion chromatograph (SIC) as hopanes. This can help one identify them in GC/MS datasets. |
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==Uses== |
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===As a biomarker=== |
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Oleanane has been identified as a compound in modern day angiosperms.<ref>{{Cite journal|title=Naturally occurring seco-ring-A-triterpenoids and their possible biological significance|last=Baas|first=Wim J.|issue=9|pages=1875–1889|journal=Phytochemistry|volume=24|doi=10.1016/s0031-9422(00)83085-x|date=January 1985|bibcode=1985PChem..24.1875B }}</ref> |
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Because of this, its presence is the fossil record has also been used to trace angiosperms through the fossil record. For example, the ratio of 18-alpha-oleanane + 18-beta-oleanane:17-alpha-hopane in rock extracts (and associated petroleums/oils) has been found to correlate (at least broadly) to the presence of angiosperms in the fossil record.<ref name=":2">{{Cite journal|last1=Taylor|first1=David Winship|last2=Peakman|first2=Torren M.|last3=Hickey|first3=Leo J.|last4=Fago|first4=Frederick J.|last5=Huizinga|first5=Bradley J.|last6=Dahl|first6=Jeremy|last7=Moldowan|first7=J. Michael|date=1994-08-05|title=The Molecular Fossil Record of Oleanane and Its Relation to Angiosperms|journal=Science|language=en|volume=265|issue=5173|pages=768–771|doi=10.1126/science.265.5173.768|issn=0036-8075|pmid=17736275|bibcode=1994Sci...265..768M}}</ref> In this study, the combination of alpha and beta-oleanane were used as indicators for the presence of angiosperms. They are normalized to hopanes, which are broadly present in almost all rock extracts coming from petroleum. Furthermore, because of the structural similarities between hopanes and oleananes, it is assumed that they will react similarly to the various weathering processes that degrade the biomarkers present. As such, the ratio of hopanes to oleananes should be similar to the initial ratio, and unaffected by processes occurring in the rock after fossilization. |
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There is some delay in the accepted increases in taxonomic diversification of angiosperms (which occurred during the mid-Cretaceous period) and the increase of oleanane concentrations in the fossil record (which occurred in the late-Cretaceous or even after). This could be due to a number of factors, one being that the early angiosperms were more herbaceous than woody and that woody angiosperms only appeared after further taxonomic diversification.<ref name=":2" /> |
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Lastly, the study introduced the idea of an "oleanane parameter," which could be used in assessing angiosperm input to petroleum sources. This, in turn, gives some idea of the age of said petroleum sources.<ref name=":2" /> |
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That being said, the presence of angiosperms may not be the only thing affecting the oleanane content of sediments, rock extracts and petroleum. For example, there is evidence that contact with seawater during early sedimentation processes can increase the concentration of oleananes in the mature sediment.<ref name=":1">{{Cite web|url=https://www.researchgate.net/publication/223465178|title=Oleananes in oils and sediments: Evidence of marine influence during early diagenesis? {{!}} Request PDF|website=ResearchGate|language=en|access-date=2019-05-15}}</ref> This evidence comes from the fact that various indicators of marine influence (C27/C29 sterane ratios, changes in elemental composition in the downstream direction that are indicative of the infiltration of water into the system and the homophane index). Despite this, it is still unclear as to how marine influence enhances the expression of oleananes (thus increasing observed concentration). Some ideas include the changes in pH, Eh and the microbial environment that come with the interaction with seawater.<ref name=":1" /> |
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== See also == |
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*] |
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==References== |
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==References== |
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{{reflist}} |
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{{Reflist}} |
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