Each essential oil derived from an aromatic plant is a mixture of 100 or more compounds which can be grouped into different categories such as monoterpenes, sesquiterpenes, phenylpropanoids etc. Many of these compounds are synthesized by mevalonic acid or shikimic acid pathways. What are the other classes of compounds and by which pathways they are synthesized?
Dear Rao,
There is a latest discovery of biosynthetic pathway to produce isoprene, and of course terpenoids in the plant cells and other organisms, called as a non-mevalonate pathway or DOXP pathway or 1-deoxy-D-xylulose 5-phosphate pathway. This bio-synthetic machinery take place on their plastids.
You can googling this topic and you will find out many articles.
Cheers
Dear Dr. Andria Agusta
Thanks. What about the classes of compounds? Can you throw some light on this topic as well?
Good luck.
Despite the remarkable diversity of plants terpenoids, the various pathways that direct the synthesis of these metabolites were thought to emerge from a single common biosynthetic pathways-the mevolanate-isoprenoid pathway (MVA pathway), named after its known intermediate mevalonic acid. In MVA, synthesis of biological C5 isoprene unit- the isopentenyl pyrophosphate (IPP) from three molecules of acetyl-CoA as mevalonic acid as intermediate. In second step IPP is isomerised to dimethy allyl pyrophosphate (DMAPP) and these two isomers combine to yield geranyl pyrophosphate (GPP, C10). Further condensation gives sesqui, diterpenoids etc. But besides the ubiquitous MVA pathway, IPP and DMAPP are also biosynthesized via a mevolanate independent pathway (MEP) which is called as triose-phosphate/pyruvate pathway or deoxy-xylulose phosphate pathway (DEXP). Studies also indicated that in higher plants, monoterpenoids, diterpenoids, carotenoids and phytol chains of chlorophyll are formed via the deoxy-xylulose phosphate pathway (DEXP) not by classical mevolanate-isoprenoid pathway. So one can presume that some terpenoids may be synthesized through the mevolanate pathway and other by deoxy-xylulose phosphate pathway (DEXP). Further more, some terpenoids are also shown to have mixed origin by both pathways. Analysis of labeling pattern and quantitative 13C-NMR spectroscopy of sesquiterpene bisaboloxide A and chemazulene isolated from Matericaria recutita (Chamomile) flowers showed that two of isoprene building blocks were predominantly formed by triose-phosphate/pyruvate pathway whereas the third unit is mixed origin, being derived from both MVA pathway and triose-phosphate/pyruvate pathway.
There are some nitrogenous compounds were also identified in some of essential oils. One of essential oils containing such compounds is vetiver oil from Hati.
Please refer this link: http://www.tandfonline.com/doi/abs/10.1080/10412905.2005.9699005#.VOagbCwykg8
Oil from black pepper was also contain nitrogenous compound.
http://www.tandfonline.com/doi/abs/10.1080/10412905.2006.9699369#.VOahtSwykg8
regards
Dear Padalia and Agusta
Thank you for your useful contributions. I am looking for different classes of compounds like monoterpenes, sesquiterpenes, oxygenated mono/sesqui terpenes, phenyl propanoids, nitrogen/sulphur containing compounds etc. What are the other classes of compounds? In to how many classes the essential oil components can be grouped into?
What about shikimate/shikimic acid pathway. Some aroma compounds are synthesized from amino acids. Any other latest pathways?
Best wishes and good luck.
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