Brassicasterol (24-methyl cholest-5,22-dien-3β-ol) is a 28-carbonsterol synthesised by several unicellularalgae (phytoplankton) and some terrestrial plants, like rape. This compound has frequently been used as a biomarker for the presence of (marine) algal matter in the environment, and is one of the ingredients for E numberE499. There is some evidence to suggest that it may also be a relevant additional biomarker in Alzheimer's disease.[1]
Brassicasterol has a low water solubility and, as a consequence, a high octanol-water partition coefficient. This means that, in most environmental systems, brassicasterol will be associated with the solid phase.
Degradationedit
In anaerobic sediments and soils, brassicasterol is stable for many hundreds of years, enabling it to be used as an indicator of past algal production (see below).
Chemical analysisedit
Since the molecule has a hydroxyl (-OH) group, it is frequently bound to other lipids including glycerols; most analytical methods, therefore, utilise a strong alkali (KOH or NaOH) to saponify the ester linkages. Typical extraction solvents include 6% KOH in methanol. The free sterols are then separated from the polar lipids by partitioning into a less polar solvent such as hexane. Prior to analysis, the hydroxyl group is frequently derivatised with BSTFA (bis-trimethyl silyl trifluoroacetamide) to replace the hydrogen with the less exchangeable trimethylsilyl (TMS) group. Instrumental analysis is frequently conducted on gas chromatograph (GC) with either a flame ionisation detector (FID) or mass spectrometer (MS). The mass spectrum for the TMS ether of brassicasterol can be seen in the figure. [citation needed]
Brassicasterol is formed in plants from the isoprenoidsqualene through campesterol as an intermediate. A list of the algae in which brassicasterol has been identified is shown below together with approximate composition.[3]
Sterol content of selected dinoflagellates (as percentage). Data from Volkman, 1986
The principal source of brassicasterol in the environment is from marine algae. Its relatively high concentration and stability allows it to be used in the assessment of the origin of organic matter in samples, especially sediments.
Brassicasterol / cholesterol ratioedit
The concentration of brassicasterol in a core sample from Loch Striven, Scotland. Highest values may be seen in the top sections of the sediment, which decrease with depth. However, the cholesterol behaves in a similar manner, and the ratio brassicasterol/cholesterol is fairly uniform at all depths, indicating either a comparable degradation rate with no change in source or different degradation rates and a change in source.
Multivariate analysisedit
Multivariate statistical analyses such as principal component analysis of a range of lipid biomarkers (e.g., other sterols, fatty acids, and fatty alcohols) enable identification of compounds that have similar origins or behaviour. An example can be seen in the loadings plot for sediment samples from the Mawddach Estuary, Wales.
The location of brassicasterol in this figure (shown in red) indicates that the distribution of this compound is similar to that of the short-chain fatty acids and alcohols, which are known to be of marine origin. The terrestrially derived biomarkers such as β-sitosterol are on the opposite side of the figure and are mutually exclusive.
Referencesedit
^Vanmierlo, T.; Popp, J.; Kölsch, H.; Friedrichs, S.; Jessen, F.; Stoffel-Wagner, B.; Bertsch, T.; Hartmann, T.; Maier, W.; von Bergmann, K.; Steinbusch, H.; Mulder, M.; Lütjohann, D. (September 2011). "The plant sterol brassicasterol as additional CSF biomarker in Alzheimer's disease: Plant sterols as biomarker in AD". Acta Psychiatrica Scandinavica. 124 (3): 184–192. doi:10.1111/j.1600-0447.2011.01713.x. PMID 21585343. S2CID 25346711.
^Constituents of Mirabilis jalapa. Siddiqui S., Siddiqui B.S., Adil Q. and Begum S., Fitoterapia, 1990, Volume 61, No. 5, page 471 (abstract 2014-01-04 at the Wayback Machine)
brassicasterol, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, june, 2018,. This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Brassicasterol news newspapers books scholar JSTOR June 2018 Learn how and when to remove this template message Brassicasterol 24 methyl cholest 5 22 dien 3b ol is a 28 carbon sterol synthesised by several unicellular algae phytoplankton and some terrestrial plants like rape This compound has frequently been used as a biomarker for the presence of marine algal matter in the environment and is one of the ingredients for E number E499 There is some evidence to suggest that it may also be a relevant additional biomarker in Alzheimer s disease 1 Brassicasterol NamesIUPAC name Ergosta 5 22 dien 3b olSystematic IUPAC name 1R 3aS 3bS 7S 9aR 9bS 11aR 1 2R 3E 4R 5 6 Dimethylhept 3 en 2 yl 9a 11a dimethyl 2 3 3a 3b 4 6 7 8 9 9a 9b 10 11 11a tetradecahydro 1H cyclopenta a phenanthren 7 olOther names brassicasterol 3b 22E ergosta 5 22 dien 3 ol24b methylcholesta 5 22 dien 3 beta ol24 methyl cholest 5 22 dien 3b olIdentifiersCAS Number 474 67 9 Y3D model JSmol Interactive imageChEBI CHEBI 3168ChemSpider 4444704 YECHA InfoCard 100 006 807PubChem CID 6432458UNII 2B0KG2XFOF YCompTox Dashboard EPA DTXSID80197124InChI InChI 1S C28H46O c1 18 2 19 3 7 8 20 4 24 11 12 25 23 10 9 21 17 22 29 13 15 27 21 5 26 23 14 16 28 24 25 6 h7 9 18 20 22 26 29H 10 17H2 1 6H3 b8 7 t19 20 22 23 24 25 26 27 28 m0 s1 YKey OILXMJHPFNGGTO ZAUYPBDWSA N YInChI 1 C28H46O c1 18 2 19 3 7 8 20 4 24 11 12 25 23 10 9 21 17 22 29 13 15 27 21 5 26 23 14 16 28 24 25 6 h7 9 18 20 22 26 29H 10 17H2 1 6H3 b8 7 t19 20 22 23 24 25 26 27 28 m0 s1Key OILXMJHPFNGGTO ZAUYPBDWBSSMILES O C H 4C C3 C C C H 1 C H CC C 2 C H CC C H 12 C H C C C H C C C C C C C 3 C CC4PropertiesChemical formula C 28H 46OMolar mass 398 675 g mol 1Appearance White solidMelting point 150 to 151 C 302 to 304 F 423 to 424 K HazardsFlash point Non flammableRelated compoundsRelated Sterols cholesterolb sitosterolcampesterolstigmasterolExcept where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa N verify what is Y N Infobox references Contents 1 Chemical properties 1 1 Solubility 1 2 Degradation 1 3 Chemical analysis 2 Formation and occurrences 2 1 Algal sources 3 Use as a tracer for marine algae 3 1 Brassicasterol cholesterol ratio 3 2 Multivariate analysis 4 ReferencesChemical properties editSolubility edit Brassicasterol has a low water solubility and as a consequence a high octanol water partition coefficient This means that in most environmental systems brassicasterol will be associated with the solid phase Degradation edit In anaerobic sediments and soils brassicasterol is stable for many hundreds of years enabling it to be used as an indicator of past algal production see below Chemical analysis edit Since the molecule has a hydroxyl OH group it is frequently bound to other lipids including glycerols most analytical methods therefore utilise a strong alkali KOH or NaOH to saponify the ester linkages Typical extraction solvents include 6 KOH in methanol The free sterols are then separated from the polar lipids by partitioning into a less polar solvent such as hexane Prior to analysis the hydroxyl group is frequently derivatised with BSTFA bis trimethyl silyl trifluoroacetamide to replace the hydrogen with the less exchangeable trimethylsilyl TMS group Instrumental analysis is frequently conducted on gas chromatograph GC with either a flame ionisation detector FID or mass spectrometer MS The mass spectrum for the TMS ether of brassicasterol can be seen in the figure nbsp citation needed Formation and occurrences editIt can be found in Mirabilis jalapa 2 Algal sources edit Brassicasterol is formed in plants from the isoprenoid squalene through campesterol as an intermediate A list of the algae in which brassicasterol has been identified is shown below together with approximate composition 3 Sterol content of selected dinoflagellates as percentage Data from Volkman 1986 Species A B C D E F G H othersGonyaulax spp 100 0 0 0 0 0 0 0 0Peridinium foliaceum 100 0 0 0 0 0 0 0 0Peridinium foliaceum 80 20 0 0 0 0 0 0 0Gonyaulax diegensis 39 0 0 0 0 0 0 29 32Pyrocystis lunula 76 6 0 2 1 0 0 0 15Gonyaulax polygramma 36 1 0 9 7 0 0 0 47Gymnodinium wilczeki 26 39 0 35 1 0 0 0 0Glenodinium hallii 8 50 0 0 0 42 0 0 0Noctiluca milaris 0 1 1 5 73 0 6 0 14Gymnodinium simplex 0 0 0 0 53 0 0 0 47Prorocentrum cordatum 7 0 0 0 5 0 63 0 25A cholesterol B campesterol C sitosterol D 22 dehydrocholesterol 22E cholesta 5 22 dien 3b ol E brassicasterol F stigmasterol G 24 methylene cholesterol H fucosterolUse as a tracer for marine algae editThe principal source of brassicasterol in the environment is from marine algae Its relatively high concentration and stability allows it to be used in the assessment of the origin of organic matter in samples especially sediments Brassicasterol cholesterol ratio edit nbsp The concentration of brassicasterol in a core sample from Loch Striven Scotland Highest values may be seen in the top sections of the sediment which decrease with depth However the cholesterol behaves in a similar manner and the ratio brassicasterol cholesterol is fairly uniform at all depths indicating either a comparable degradation rate with no change in source or different degradation rates and a change in source Multivariate analysis edit Multivariate statistical analyses such as principal component analysis of a range of lipid biomarkers e g other sterols fatty acids and fatty alcohols enable identification of compounds that have similar origins or behaviour An example can be seen in the loadings plot for sediment samples from the Mawddach Estuary Wales nbsp The location of brassicasterol in this figure shown in red indicates that the distribution of this compound is similar to that of the short chain fatty acids and alcohols which are known to be of marine origin The terrestrially derived biomarkers such as b sitosterol are on the opposite side of the figure and are mutually exclusive References edit Vanmierlo T Popp J Kolsch H Friedrichs S Jessen F Stoffel Wagner B Bertsch T Hartmann T Maier W von Bergmann K Steinbusch H Mulder M Lutjohann D September 2011 The plant sterol brassicasterol as additional CSF biomarker in Alzheimer s disease Plant sterols as biomarker in AD Acta Psychiatrica Scandinavica 124 3 184 192 doi 10 1111 j 1600 0447 2011 01713 x PMID 21585343 S2CID 25346711 Constituents of Mirabilis jalapa Siddiqui S Siddiqui B S Adil Q and Begum S Fitoterapia 1990 Volume 61 No 5 page 471 abstract Archived 2014 01 04 at the Wayback Machine Data from a review by Volkman 1986 clarification needed Retrieved from https en wikipedia org w index php title Brassicasterol amp oldid 1152386465, wikipedia, wiki, book, books, library,
