Geosmin

Structural formula
General
Surname	Geosmin
other names	(4 S , 4a S , 8a R ) -4,8a-dimethyl-1,2,3,4,5,6,7,8-octahydronaphthalen-4a-ol; 2,6-dimethylbicyclo [4.4.0] decan-1-ol; Octahydro-4,8a-dimethyl-4a (2 H ) -naphthalenol;
Molecular formula	C 12 H 22 O
Brief description	oil smelling of earth
External identifiers / databases
EC number	243-239-8
ECHA InfoCard	100.039.294
PubChem	29746
ChemSpider	27642
Wikidata	Q420233
properties
Molar mass	182.31 g · mol -1
Physical state	liquid
boiling point	270 ° C
solubility	readily soluble in alcohols , poorly soluble in water
safety instructions
GHS labeling of hazardous substances Caution
H and P phrases	H: 302
	P: ?
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Geosmin is a naturally occurring bicyclic , tertiary alcohol . The substance has a pronounced earthy, musty smell and taste and is one of the causes of the sensation perceived as a typical floor smell, but also of the smell of mold .

Geosmin is also involved in the odor perception that occurs when it rains, especially after a long period of drought. This smell is also called Petrichor .

Occurrence

Fruiting bodies of myxobacteria ( Myxococcus xanthus )

Geosmin is produced by microorganisms , especially Streptomyces species and myxobacteria . These organisms live mainly in the soil. Geosmin formation by cyanobacteria can cause an earthy odor in fresh water and is difficult to remove from it because the perception limit is very low. Geosmin has also been found in plants such as beetroot ( Beta vulgaris ), beans, and wine.

biosynthesis

In the first step of biosynthesis , the phosphate residue is split off from farnesyl pyrophosphate 1 , and the ring is closed by the rearrangement pair of electrons in the double bond . The alcohol group is formed through a nucleophilic attack by a hydroxide ion in the temporarily formed three-membered ring of 2 . Acetone is then split off from the germacradiene derivative 3 to form the bicycle 4 . Another nucleophilic attack with a hydroxide ion and the hydrogenation of the double formation creates geosmin 5 .

Geosmin and the derivative dehydrogeosmin have a similar biosynthetic pathway. This could be the reason that both substances can be detected in cacti .

Others

The human sense of smell is highly sensitive to geosmin; the odor threshold is 0.1 ppb . An earthy smell in the wine indicates a wine fault . In addition, the earthy tone can often be associated with a cork tone . In Petri Choir , the earthy smell that can be smelled at the beginning of rain after warm weather, geosmin is also detectable.

literature

Römpp-Lexikon Naturstoffe, Thieme, Stuttgart, 1997, ISBN 3-13-749901-1 .

Individual evidence

↑ ^a ^b ^c ^d Entry on Geosmin. In: Römpp Online . Georg Thieme Verlag, accessed on May 29, 2014.
↑ thegoodscentscompany.com: Geosmin .
↑ Template: CL Inventory / not harmonized There is not yet a harmonized classification for this substance . A labeling of [4S- (4α, 4aα, 8aβ)] - octahydro-4,8a-dimethyl-4a (2H) -naphthol in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA) is reproduced, which is derived from a self-classification by the distributor on November 5, 2017.
↑ Wolfgang Legrum: Fragrances, between stink and fragrance , Vieweg + Teubner Verlag (2011) p. 65, ISBN 978-3-8348-1245-2 .
↑ Dieter Spiteller: Characterization of N-acyl-glutamine conjugates from the regurgitation of Lepidoptera larvae , dissertation, Friedrich Schiller University Jena, Jena 2002, pp. 98–116.
↑ DE Cane, X. He, S. Kobayashi, S. Ömura, H. Ikeda: Geosmin Biosynthesis in Streptomyces avermitilis. Molecular Cloning, Expression and Mechanistic Study of the Germacradienol / Geosmin Synthesis , in: Nature Journal , 2006, 59 (8), pp. 471-479; doi : 10.1038 / yes 2006.66 .
↑ Institut Viti-Vinicole: putrefaction complex "Penicillium, Frühbotrytis, vinegar rot": Securing the grape quality through a loose grape structure. ( Memento of May 18, 2008 in the Internet Archive ).

[roempp-1] Entry on Geosmin. In: Römpp Online . Georg Thieme Verlag, accessed on May 29, 2014.

[2] thegoodscentscompany.com: Geosmin .

[3] Template: CL Inventory / not harmonized There is not yet a harmonized classification for this substance . A labeling of [4S- (4α, 4aα, 8aβ)] - octahydro-4,8a-dimethyl-4a (2H) -naphthol in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA) is reproduced, which is derived from a self-classification by the distributor on November 5, 2017.

[Legrum-4] Wolfgang Legrum: Fragrances, between stink and fragrance , Vieweg + Teubner Verlag (2011) p. 65, ISBN 978-3-8348-1245-2 .

[5] Dieter Spiteller: Characterization of N-acyl-glutamine conjugates from the regurgitation of Lepidoptera larvae , dissertation, Friedrich Schiller University Jena, Jena 2002, pp. 98–116.

[6] DE Cane, X. He, S. Kobayashi, S. Ömura, H. Ikeda: Geosmin Biosynthesis in Streptomyces avermitilis. Molecular Cloning, Expression and Mechanistic Study of the Germacradienol / Geosmin Synthesis , in: Nature Journal , 2006, 59 (8), pp. 471-479; doi : 10.1038 / yes 2006.66 .

[7] Institut Viti-Vinicole: putrefaction complex "Penicillium, Frühbotrytis, vinegar rot": Securing the grape quality through a loose grape structure. ( Memento of May 18, 2008 in the Internet Archive ).