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Germacrenes are a group of naturally occurring volatile organic hydrocarbons of the sesquiterpene and cycloalkene class. They are typically produced in plants and have antimicrobial and insecticidal properties, though they also play a role as insect pheromones. Two prominent molecules are germacrene A and germacrene D.

Structures

Germacrene has five structural isomers.[1]

Germacrene isomers
Germacrene A Germacrene B Germacrene C Germacrene D Germacrene E
(–)-Germacrene A Germacrene B Germacrene C Germacrene D Germacrene E

Germacrene A is chiral and both the (–)-(S) and (+)-(R) forms are found naturally.[1] Germacrene D is also known in both enantiomeric forms.[2]

Natural occurrences

The essential oils of deadnettles (genus Lamium),[3] hedgenettles (genus Stachys),[4] and Clausena anisata are characterized by their high contents of germacrene D. Germacrene B is a major component of patchouli oil.[5]

Metabolism in plants

The germacrenes are precursors to sesquiterpene lactones.[6] For example, the enzyme germacrene A hydroxylase in chicory converts (+)-germacrene A to a carboxylic acid which is the starting material for costunolide synthase, which converts it to costunolide:[7][8]

2D representation of the chemical structure of Q27104477.
(+)-germacrene A
Oxidase
 
 
Rightward reaction arrow
 
 
 
2D representation of the chemical structure of Q27131000.
(+)-germacrene A acid
Synthase
 
 
Rightward reaction arrow
 
 
 
2D representation of the chemical structure of costunolide .
costunolide


References

  1. ^ a b Adio, A. M. (2009). “Germacrenes A–E and related compounds: thermal, photochemical and acid induced transannular cyclizations”. Tetrahedron. 65 (8): 1533–1552. doi:10.1016/j.tet.2008.11.050.
  2. ^ Arimura, G.-I.; Huber, D. P. W.; Bohlmann, J. (2004). “Forest tent caterpillars (Malacosoma disstria) induce local and systemic diurnal emissions of terpenoid volatiles in hybrid poplar (Populus trichocarpa × deltoides): cDNA cloning, functional characterization, and patterns of gene expression of (−)-germacrene D synthase, PtdTPS1“. The Plant Journal. 37 (4): 603–616. doi:10.1111/j.1365-313X.2003.01987.x. PMID 14756770.
  3. ^ Flamini, G.; Cioni, P. L.; Morelli, I. (2005). “Composition of the essential oils and in vivo emission of volatiles of four Lamium species from Italy: L. purpureum, L. hybridum, L. bifidum and L. amplexicaule“. Food Chemistry. 91 (1): 63–68. doi:10.1016/j.foodchem.2004.05.047.
  4. ^ Morteza-Semnani, K.; Akbarzadeh, M.; Changizi, Sh. (2005-11-01). “Essential oils composition of Stachys byzantina, S. inflata, S. lavandulifolia and S. laxa from Iran”. Flavour and Fragrance Journal. 21 (2): 300–303. doi:10.1002/ffj.1594.
  5. ^ Hasegawa, Yoshihiro; Tajima, Katsuhiko; Toi, Nao; Sugimura, Yukio (1992). “An additional constituent occurring in the oil from a patchouli cultivar”. Flavour and Fragrance Journal. 7 (6): 333–335. doi:10.1002/ffj.2730070608. ISSN 0882-5734.
  6. ^ Ghantous, Akram; Gali-Muhtasib, Hala; Vuorela, Heikki; Saliba, Najat A.; Darwiche, Nadine (2010). “What Made Sesquiterpene Lactones Reach Cancer Clinical Trials?”. Drug Discovery Today. 15 (15–16): 668–678. doi:10.1016/0305-1978(86)90101-8. PMID 20541036.
  7. ^ de Kraker JW, Franssen MC, Dalm MC, de Groot A, Bouwmeester HJ (April 2001). “Biosynthesis of germacrene A carboxylic acid in chicory roots. Demonstration of a cytochrome P450 (+)-germacrene a hydroxylase and NADP+-dependent sesquiterpenoid dehydrogenase(s) involved in sesquiterpene lactone biosynthesis”. Plant Physiology. 125 (4): 1930–40. doi:10.1104/pp.125.4.1930. PMC 88848. PMID 11299372.
  8. ^ de Kraker JW, Franssen MC, Joerink M, de Groot A, Bouwmeester HJ (May 2002). “Biosynthesis of costunolide, dihydrocostunolide, and leucodin. Demonstration of cytochrome p450-catalyzed formation of the lactone ring present in sesquiterpene lactones of chicory”. Plant Physiology. 129 (1): 257–68. doi:10.1104/pp.010957. PMC 155889. PMID 12011356.

Further reading

Germacrene A

Germacrene D

  • Rivero Cruz, B.; Rivero Cruz, I; Rodríguez, J. M.; Cerda García-Rojas, C. M.; Mata, R. (2006-08-01). “Qualitative and quantitative analysis of the active components of the essential oil from ‘Brickellia veronicaefolia by nuclear magnetic resonance spectroscopy”. Journal of Natural Products. 69 (8): 1172–1176. Bibcode:2006JNAtP..69.1172R. doi:10.1021/np060180b. PMID 16933870.
  • Yang, F.-Q.; Li, S.-P.; Chen, Y.; Lao, S.-C.; Wang, Y.-T.; Dong, T.-T.; Tsim, K.-W. (2005-09-15). “Identification and quantitation of eleven sesquiterpenes in three species of Curcuma rhizomes by pressurized liquid extraction and gas chromatography-mass spectrometry”. Journal of Pharmaceutical and Biomedical Analysis. 39 (3–4): 552–558. doi:10.1016/j.jpba.2005.05.001. PMID 15946818.
  • Umlauf, D.; Zapp, J.; Becker, H.; Adam, K. P. (2004-09-01). “Biosynthesis of the irregular monoterpene artemisia ketone, the sesquiterpene germacrene D and other isoprenoids in Tanacetum vulgare L. (Asteraceae)”. Phytochemistry. 65 (17): 2463–2470. Bibcode:2004PChem..65.2463U. doi:10.1016/j.phytochem.2004.08.019. PMID 15381410.
  • Agnihotri, V. K.; Thappa, R. K.; Meena, B.; Kapahi, B. K.; Saxena, R. K.; Qazi, G. N.; Agarwal, S. G. (2004-08-01). “Essential oil composition of aerial parts of Angelica glauca growing wild in North-West Himalaya (India)”. Phytochemistry. 65 (16): 2411–2413. Bibcode:2004PChem..65.2411A. doi:10.1016/j.phytochem.2004.07.004. PMID 15381015.
  • Raal, A.; Paaver, U.; Arak, E.; Orav, A. (2004). “Content and composition of the essential oil of Thymus serpyllum L. growing wild in Estonia”. Medicina (Kaunas). 40 (8): 795–800. PMID 15300002.
  • He, X.; Cane, D. E. (2004-03-10). “Mechanism and stereochemistry of the germacradienol/germacrene D synthase of Streptomyces coelicolor A3(2)”. Journal of the American Chemical Society. 126 (9): 2678–2679. Bibcode:2004JAChS.126.2678H. doi:10.1021/ja039929k. PMID 14995166.