Abietane

Last updated
Abietane
Abietane.svg
Names
IUPAC name
Abietane
Systematic IUPAC name
(4aR,4bS,7S,8aS,10aS)-1,1,4a-Trimethyl-7-(propan-2-yl)tetradecahydrophenanthrene
Other names
13α-Isopropylpodocarpane
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
PubChem CID
  • InChI=1S/C20H36/c1-14(2)15-7-9-17-16(13-15)8-10-18-19(3,4)11-6-12-20(17,18)5/h14-18H,6-13H2,1-5H3/t15-,16-,17-,18-,20+/m0/s1 Yes check.svgY
    Key: STIVVCHBLMGYSL-ZYNAIFEFSA-N Yes check.svgY
  • [H][C@]12[C@@](C[C@@H](C(C)C)CC2)([H])CC[C@@]3([H])C(C)(C)CCC[C@@]31C
Properties
C20H36
Molar mass 276.508 g·mol−1
Density 0.876 g/ml
Boiling point 338
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Abietane is a diterpene that forms the structural basis for a variety of natural chemical compounds such as abietic acid, [1] carnosic acid, and ferruginol which are collectively known as abietanes or abietane diterpenes.

Contents

Abietanes are found in the tissues and resins of certain higher plants, particularly gymnosperms. [2] [3] Although the functions of terpenes are not fully understood, conifers appear to produce abietane diterpenoids as a form of defense against insect and microbial attack. [4] [5] Some abietane diterpenoids, especially aromatic abietenes, are of interest to the pharmacology and natural products communities for their potential biological activities. [6] In the rock record, abietanes are commonly found in amber as well as in fossil wood, sometimes in the form of the mineral fichtelite. Additionally, abietanes are observed in sediments—both riverine and marine—and in coals, where they are often interpreted as geochemical biomarkers for terrestrial input from conifers. [2] [7] [4] [8] [9]

Chemical structure and properties

Abietane skeleton numbering scheme Abietane Numbering.svg
Abietane skeleton numbering scheme

Abietanes are tricyclic 20-carbon diterpenoids characterized by three fused six-membered rings and alkyl functional groups at carbons 4, 10, and 13. In higher plants, abietanes and other diterpenoids are synthesized from four five-carbon isoprene units. Abietanes are generally nonpolar, volatile, and less dense than water. The presence of one or more polar functional groups (typically a carboxylic acid or alcohol) tends to increase the polarity and boiling point of a given abietane relative to its unsubstituted hydrocarbon form.

Biological sources and synthesis

Abietenes are synthesized from geranylgeranyl diphosphate via a copalyl diphosphate intermediate by class 2 diterpene cyclases and class 1 diterpene syntheses. Geranylgeranyl diphosphate to copalyl diphosphate mechanism from Peters 2010.svg
Abietenes are synthesized from geranylgeranyl diphosphate via a copalyl diphosphate intermediate by class 2 diterpene cyclases and class 1 diterpene syntheses.

In higher plants, abietanes are synthesized from geranylgeranyl diphosphate (GGPP) via a copalyl diphosphate (CPP) intermediate. First, GGPP is cyclized by a class II diterpene cyclase enzyme to CPP. The conformation of the GGPP molecule dictates the stereochemistry of the CPP intermediate after cyclization. The stereochemistry of the typical abietane skeleton suggests a GGPP precursor with its fused cyclohexyl rings in a chair-chair ("normal") conformation, although some abietanes with alternative stereochemistry may be cyclized from CCP isomers containing alternative combinations of boat and chair cyclohexane conformers. After the initial cyclization to CPP, which forms rings A and B in the abietane skeleton, the C ring is formed with the help of a class I diterpene synthase enzyme. Subsequent methyl migration and dehydrogenation steps yield the abietene isomers. [10]

Preservation and diagenesis

Proposed diagenetic pathway for abietic acid involving defunctionalization and aromatization to form retene Abietic Acid Diagenesis horizontal.svg
Proposed diagenetic pathway for abietic acid involving defunctionalization and aromatization to form retene
Abietanes found in the rock record are typically interpreted as evidence of higher plants, particularly gymnosperms, in the deep past. Abietane Diagenesis Scheme.svg
Abietanes found in the rock record are typically interpreted as evidence of higher plants, particularly gymnosperms, in the deep past.

Diagenetic transformation of biomolecules is not fully understood, but several broad diagenetic patterns are hypothesized to affect the transformation of abietanes as they are heated and pressurized in sediments. The first of these patterns is defunctionalization. In particular, the reducing conditions of diagenesis are believed to cause abietanes to lose oxygen-containing functional groups, including carboxylic acids and alcohols, as well as methyl groups. [8] In addition to defunctionalization, abietanes likely undergo dehydrogenation and aromatization reactions to form more energetically stable systems of conjugated pi bonds in their characteristic three ring structure. The hypothesized diagenetic pathway of abietic acid is illustrative of these general patterns. Abietic acid is dehydrogenated to dehydroabietic acid, which then loses its carboxylic acid functional group to become dehydroabietin. Loss of the 5-Me group and further dehydrogenation form the aromatic 1,2,3,4-tetrahydroretene molecule. Final aromatization produces retene, a common biomarker molecule observed in sedimentary samples. [8]

Measurement techniques

Abietanes found in modern gymnosperm resins as well as in the rock record are separated and characterized by gas chromatography-mass spectrometry (GC-MS). Because polar functional groups reduce molecular volatility and make separation by gas chromatography difficult, abietane derivatives containing carboxylic acid and alcohol moieties are often derivatized with trimethylsilyl groups by treatment with BSTFA prior to GC-MS analysis. [11] More oxidized abietane derivatives have been studied using thermally assisted methylation using tetramethylammonium hydroxide (TMAH) followed by GC-MS analysis. [12] MS-MS analysis has been used to elucidate fragmentation mechanisms for mass spectrum peaks of interest. [11] Mass spectra for abietic acid and some other common abietanes are publicly available in the NIST database. [13] The spectrum for abietic acid possesses characteristic peaks at m/z = 256 and 241. [11]

Use as a biomarker

Abietanes preserved in geological settings are typically interpreted to derive from gymnosperms, specifically conifers. [9] [8] [4] Although both modern angiosperms and modern gymnosperms synthesize terpenoids, gymnosperm tissues tend to contain significantly higher terpenoid concentrations than angiosperm tissues. [3] Additionally, the relative abundances of di-, tri-, and penta-cyclic terpenoids varies between gymnosperms and angiosperms. Although some angiosperm families (notably Burseraceae, Euphorbiaceae and Ranunculaceae) are also known to produce abietanes, in general, tricyclic diterpenoids, including abietanes, are much more abundant in gymnosperms. [3] [2] For these reasons, and because conifers produce significant biomass relative to other gymnosperms, abietanes preserved in geological settings are typically interpreted as conifer biomarkers. It is important to note, however, that such interpretations rely on the assumption that terpenoid distributions and abundances in ancient plants were similar to those in modern plants. Loss of more volatile mono- and sesquiterpenoids during diagenetic heating may help explain the different relative abundance of diterpenoids, including abietanes, in ancient resins and the rock record compared to modern conifer samples. [9]

Examples from archaeology

Examples from geochemistry

See also

Related Research Articles

The terpenoids, also known as isoprenoids, are a class of naturally occurring organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeably with "terpenes", terpenoids contain additional functional groups, usually containing oxygen. When combined with the hydrocarbon terpenes, terpenoids comprise about 80,000 compounds. They are the largest class of plant secondary metabolites, representing about 60% of known natural products. Many terpenoids have substantial pharmacological bioactivity and are therefore of interest to medicinal chemists.

<span class="mw-page-title-main">Terpene</span> Class of oily organic compounds found in plants

Terpenes are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. In plants, terpenes and terpenoids are important mediators of ecological interactions, while some insects use some terpenes as a form of defense. Other functions of terpenoids include cell growth modulation and plant elongation, light harvesting and photoprotection, and membrane permeability and fluidity control.

Organic geochemistry is the study of the impacts and processes that organisms have had on the Earth. It is mainly concerned with the composition and mode of origin of organic matter in rocks and in bodies of water. The study of organic geochemistry is traced to the work of Alfred E. Treibs, "the father of organic geochemistry." Treibs first isolated metalloporphyrins from petroleum. This discovery established the biological origin of petroleum, which was previously poorly understood. Metalloporphyrins in general are highly stable organic compounds, and the detailed structures of the extracted derivatives made clear that they originated from chlorophyll.

Diterpenes are a class of terpenes composed of four isoprene units, often with the molecular formula C20H32. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being a primary intermediate. Diterpenes form the basis for biologically important compounds such as retinol, retinal, and phytol. They are known to be antimicrobial and anti-inflammatory.

Resin acid refers to mixtures of several related carboxylic acids, primarily abietic acid, found in tree resins. Nearly all resin acids have the same basic skeleton: three fused rings having the empirical formula C19H29COOH. Resin acids are tacky, yellowish gums that are water-insoluble. They are used to produce soaps for diverse applications, but their use is being displaced increasingly by synthetic acids such as 2-ethylhexanoic acid or petroleum-derived naphthenic acids.

<span class="mw-page-title-main">Cholestane</span> Chemical compound

Cholestane is a saturated tetracyclic triterpene. This 27-carbon biomarker is produced by diagenesis of cholesterol and is one of the most abundant biomarkers in the rock record. Presence of cholestane, its derivatives and related chemical compounds in environmental samples is commonly interpreted as an indicator of animal life and/or traces of O2, as animals are known for exclusively producing cholesterol, and thus has been used to draw evolutionary relationships between ancient organisms of unknown phylogenetic origin and modern metazoan taxa. Cholesterol is made in low abundance by other organisms (e.g., rhodophytes, land plants), but because these other organisms produce a variety of sterols it cannot be used as a conclusive indicator of any one taxon. It is often found in analysis of organic compounds in petroleum.

<span class="mw-page-title-main">Ferruginol</span> Chemical compound

Ferruginol is a natural phenol with a terpenoid substructure. Specifically, it is a diterpene of the abietane chemical class, meaning it is characterized by three fused six-membered rings and alkyl functional groups. Ferruginol was first identified in 1939 by Brandt and Neubauer as the main component in the resin of the Miro tree and has since been isolated from other conifer species in the families Cupressaceae and Podocarpaceae. As a biomarker, the presence of ferruginol in fossils, mainly resin, is used to describe the density of these conifers in that particular biosphere throughout time.

<span class="mw-page-title-main">Labdane</span> Chemical compound

Labdane is a natural bicyclic diterpene. It forms the structural core for a wide variety of natural products collectively known as labdanes or labdane diterpenes. The labdanes were so named because the first members of the class were originally obtained from labdanum, a resin derived from the gum rockrose.

<span class="mw-page-title-main">Totarol</span> Chemical compound

Totarol is a naturally produced diterpene that is bioactive as totarol. It was first isolated by McDowell and Easterfield from the heartwood of Podocarpus totara, a conifer tree found in New Zealand. Podocarpus totara was investigated for unique molecules due to the tree's increased resistance to rotting. Recent studies have confirmed totarol's unique antimicrobial and therapeutic properties. Consequently, totarol is a candidate for a new source of drugs and has been the goal of numerous syntheses.

<span class="mw-page-title-main">Taxodone</span> Chemical compound

Taxodone is a naturally occurring diterpenoid found in Taxodium distichum, Rosmarinus officinalis (rosemary), several salvia species and other plants, along with its oxidized rearrangement product, taxodione. Taxodone and taxodione exhibit anticancer, antibacterial, antioxidant, antifungal, insecticide, and antifeedant activities.

<span class="mw-page-title-main">Levopimaric acid</span> Chemical compound

Levopimaric acid is an abietane-type of diterpene resin acid. It is a major constituent of pine oleoresin with the chemical formula of C20H30O2. In general, the abietene types of diterpene resin acid have various biological activities, such as antibacterial, cardiovascular and antioxidant. Levopimaric acid accounts for about 18 to 25% of pine oleoresin. The production of oleoresin by conifer species is an important component of the defense response against insect attack and fungal pathogen infection.

<span class="mw-page-title-main">Dinosterol</span> Chemical compound

Dinosterol (4α,23,24-trimethyl-5α-cholest-22E-en-3β-ol) is a 4α-methyl sterol that is produced by several genera of dinoflagellates and is rarely found in other classes of protists. The steroidal alkane, dinosterane, is the 'molecular fossil' of dinosterol, meaning that dinosterane has the same carbon skeleton as dinosterol, but lacks dinosterol's hydroxyl group and olefin functionality. As such, dinosterane is often used as a biomarker to identify the presence of dinoflagelletes in sediments.

Abieta-7,13-dien-18-al dehydrogenase (EC 1.2.1.74, abietadienal dehydrogenase (ambiguous)) is an enzyme with systematic name abieta-7,13-dien-18-al:NAD+ oxidoreductase. This enzyme catalyses the following chemical reaction

Abieta-7,13-diene hydroxylase (EC 1.14.13.108) is an enzyme with systematic name abieta-7,13-diene,NADPH:oxygen oxidoreductase (18-hydroxylating). This enzyme catalyses the following chemical reaction

Abieta-7,13-dien-18-ol hydroxylase (EC 1.14.13.109, CYP720B1, PTAO) is an enzyme with systematic name abieta-7,13-dien-18-ol,NADPH:oxygen oxidoreductase (18-hydroxylating). This enzyme catalyses the following chemical reaction

<span class="mw-page-title-main">Incensole</span> Chemical compound

Incensole is a C20 diterpene alcohol and biomarker for some plants of the Boswellia genus. It, along with its acetate ester incensole acetate, is an abundant component of frankincense, the resin collected from Boswellia trees. Incensole is used archaeologically to assist in identifying trade routes and distinguishing the identity of frankincense from other resins which may have been used together in incense and other salves. Incensole has also been deemed to be an active component in medicinal frankincense. 

<span class="mw-page-title-main">Sugiol</span> Chemical compound

Sugiol is a phenolic abietane derivative of ferruginol and can be used as a biomarker for specific families of conifers. The presence of sugiol can be used to identify the Cupressaceae s.1., podocarpaceae, and Araucaraiaceae families of conifers. The polar terpenoids are among the most resistant molecules to degradation besides n-alkanes and fatty acids, affording them high viability as biomarkers due to their longevity in the sedimentary record. Significant amounts of sugiol has been detected in fossil wood dated to the Eocene and Miocene periods, as well as a sample of Protopodocarpoxylon dated to the middle Jurassic.

Arborane is a class of pentacyclic triterpene consisting of organic compounds with four 6-membered rings and one 5-membered ring. Arboranes are thought to be derived from arborinols, a class of natural cyclic triterpenoids typically produced by flowering plants. Thus arboranes are used as a biomarker for angiosperms and cordaites. Arborane is a stereoisomer of a compound called fernane, the diagenetic product of fernene and fernenol. Because aborinol and fernenol have different biological sources, the ratio of arborane/fernane in a sample can be used to reconstruct a record for the relative abundances of different plants.

<span class="mw-page-title-main">Lycopane</span> Chemical compound

Lycopane (C40H82; 2,6,10,14,19,23,27,31-octamethyldotriacontane), a 40 carbon alkane isoprenoid, is a widely present biomarker that is often found in anoxic settings. It has been identified in anoxically deposited lacustrine sediments (such as the Messel formation and the Condor oil shale deposit). It has been found in sulfidic and anoxic hypersaline environments (such as the Sdom Formation). It has been widely identified in modern marine sediments, including the Peru upwelling zone, the Black Sea, and the Cariaco Trench. It has been found only rarely in crude oils.

<span class="mw-page-title-main">Chamaecydin</span> Chemical compound

Chamaecydin is a chemical compound with the molecular formula C30H40O3. It is made up of three six-membered rings and two five-membered rings and has one polar hydroxyl functional group. It is well preserved in the rock record and is only found in a specific family of conifers, the swamp cypress subfamily. The presence and abundance of chamaecydin in the rock record can reveal environmental changes in ancient biomes.

References

  1. ↑ San Feliciano, Arturo; Gordaliza, Marina; Salinero, Miguel A.; Miguel del Corral, Jose M (1993). "Abietane acids: sources, biological activities, and therapeutic uses". Planta Medica. 59 (6): 485–490. doi: 10.1055/s-2006-959744 . PMID   8302943.
  2. 1 2 3 Otto, A.; Walther, H.; Püttmann, W. (January 1997). "Sesqui- and diterpenoid biomarkers preserved in Taxodium-rich Oligocene oxbow lake clays, Weisselster basin, Germany". Organic Geochemistry. 26 (1–2): 105–115. Bibcode:1997OrGeo..26..105O. doi:10.1016/s0146-6380(96)00133-7. ISSN   0146-6380.
  3. 1 2 3 4 Diefendorf, Aaron F.; Freeman, Katherine H.; Wing, Scott L. (2012-05-15). "Distribution and carbon isotope patterns of diterpenoids and triterpenoids in modern temperate C3 trees and their geochemical significance". Geochimica et Cosmochimica Acta. 85: 342–356. Bibcode:2012GeCoA..85..342D. doi:10.1016/j.gca.2012.02.016. ISSN   0016-7037.
  4. 1 2 3 Freeman, K.H.; Pancost, R.D. (2014), "Biomarkers for Terrestrial Plants and Climate", Treatise on Geochemistry, Elsevier, pp. 395–416, doi:10.1016/b978-0-08-095975-7.01028-7, ISBN   978-0-08-098300-4 , retrieved 2021-05-10
  5. ↑ Mason, Charles J.; Klepzig, Kier D.; Kopper, Brian J.; Kersten, Philip J.; Illman, Barbara L.; Raffa, Kenneth F. (June 2015). "Contrasting Patterns of Diterpene Acid Induction by Red Pine and White Spruce to Simulated Bark Beetle Attack, and Interspecific Differences in Sensitivity Among Fungal Associates". Journal of Chemical Ecology. 41 (6): 524–532. Bibcode:2015JCEco..41..524M. doi:10.1007/s10886-015-0588-4. ISSN   0098-0331. PMID   26003180. S2CID   1506353.
  6. 1 2 González, Miguel A. (2015). "Aromatic abietane diterpenoids: their biological activity and synthesis". Natural Product Reports. 32 (5): 684–704. doi:10.1039/C4NP00110A. ISSN   0265-0568. PMID   25643290.
  7. 1 2 Simoneit, Bernd R.T.; Grimalt, J.O.; Wang, T.G.; Cox, R.E.; Hatcher, P.G.; Nissenbaum, A. (January 1986). "Cyclic terpenoids of contemporary resinous plant detritus and of fossil woods, ambers and coals". Organic Geochemistry. 10 (4–6): 877–889. Bibcode:1986OrGeo..10..877S. doi:10.1016/s0146-6380(86)80025-0. ISSN   0146-6380.
  8. 1 2 3 4 5 Killops, S. D. (1993). An introduction to organic geochemistry. V. J. Killops. Harlow, Essex, England: Longman Scientific & Technical. ISBN   0-582-08040-1. OCLC   27895324.
  9. 1 2 3 4 5 "Source- and age-related biomarker parameters", The Biomarker Guide, Cambridge University Press, pp. 483–607, 2004-12-16, doi:10.1017/cbo9781107326040.004, ISBN   978-0-521-83762-0 , retrieved 2021-05-10
  10. 1 2 Peters, Reuben J. (2010). "Two rings in them all: The labdane-related diterpenoids". Natural Product Reports. 27 (11): 1521–1530. doi:10.1039/c0np00019a. ISSN   0265-0568. PMC   3766046 . PMID   20890488.
  11. 1 2 3 Azemard, Clara; Menager, Matthieu; Vieillescazes, Catherine (2016-09-01). "Analysis of diterpenic compounds by GC-MS/MS: contribution to the identification of main conifer resins". Analytical and Bioanalytical Chemistry. 408 (24): 6599–6612. doi:10.1007/s00216-016-9772-9. ISSN   1618-2650. PMID   27449645. S2CID   8264935.
  12. 1 2 Pastorova, I.; Van Der Berg, K.J; Boon, J.J; Verhoeven, J.W (1997-08-01). "Analysis of oxidised diterpenoid acids using thermally assisted methylation with TMAH". Journal of Analytical and Applied Pyrolysis. 43 (1): 41–57. doi:10.1016/S0165-2370(97)00058-2. ISSN   0165-2370.
  13. ↑ "Abietic acid". webbook.nist.gov. Retrieved 2021-05-22.
  14. ↑ Schouten, Stefan; Woltering, Martijn; Rijpstra, W. Irene C.; Sluijs, Appy; Brinkhuis, Henk; Sinninghe Damsté, Jaap S. (June 2007). "The Paleocene–Eocene carbon isotope excursion in higher plant organic matter: Differential fractionation of angiosperms and conifers in the Arctic". Earth and Planetary Science Letters. 258 (3–4): 581–592. Bibcode:2007E&PSL.258..581S. doi:10.1016/j.epsl.2007.04.024. hdl: 1874/385783 . ISSN   0012-821X. S2CID   129625887.
  15. ↑ Simoneit, Bernd R.T (April 1977). "Diterpenoid compounds and other lipids in deep-sea sediments and their geochemical significance". Geochimica et Cosmochimica Acta. 41 (4): 463–476. Bibcode:1977GeCoA..41..463S. doi:10.1016/0016-7037(77)90285-x. ISSN   0016-7037.
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