Menthol biosynthesis and Mapping:
From the mapping Table we can conclude that; In the Menthol Biosynthesis the seven enzymes participate i.e (geranyl diphosphate synthase; Limonene synthase; limonene 3- monooxygenase; isopiperitenol dehydrogenase; pulegone reductase and menthol dehydrogenase). Here we can see that there are 25 plants which shows the orthology with menthol either with all enzyme or ,6,5,4,3,2, or with a single enzyme. This conclude that the plant showing maximum number of enzymes orthology with menthol with maximum percent Identity may produce the similar end product or some other product similar to menthol. Further in addition to this we can practice to introduce the missing enzymes in different plants so to produce the same end product or substance in that plant.
Monoterpenoids, the main volatile components in essential oils, have been used historically in the food, perfume and pharmaceutical industries because of their culinary, fragrance and antimicrobial properties. Commercially, menthol is one of the most valuable monoterpenes. The essential oils of the genus Mentha (mint) occurs in the peltate glandular trichomes. The monoterpene constituents of the essential oils of mint are distinguished by the position of oxygenation on the p-menthane ring [Lawrence 1 ]. Of the agronomically important mints, peppermint (M. piperita L.) produces almost exclusively monoterpenes bearing an oxygen function at position C-3 such as menthol (responsible for the cooling sensation of peppermint), whereas spearmint types such as native spearmint (Mentha spicata) and Scotch spearmint (M. gentilis var cardiaca) produce almost exclusively monoterpenes bearing an oxygen function at position C-6, typified by carvone (responsible for the typical spearmint note).
The biosynthesis of p-menthane monoterpenes in Mentha species proceeds from geranyl pyrophosphate via the cyclic olefin limonene. Biosynthetic investigations have demonstrated that regiospecificity is established very early on the monoterpene biosynthesis pathways in which (-)-4S-limonene, the common precursor of both oxygenated series, undergoes cytochrome P450-mediated hydroxylation at C-3 to yield (-)-trans-isopiperitenol or at C-6 to afford (-)-trans-carveol. The remaining enzymatic machinery responsible for the subsequent redox transformations of isopiperitenol to menthol is present in both peppermint and spearmint species; however, carveol is a poor substrate for these reactions, with the consequence that only the dehydrogenation product, carvone, accumulates in spearmint types [Croteau 2]. Typically, superior oils of peppermint contain high quantities of menthol, moderate amounts of menthone and low levels of pulegone and menthofurane (both of which are undesirable for their hepatotoxicity in humans). In the final reductive step of the menthol biosynthesis pathway, (-)-menthone and (+)-isomenthone are reduced to (-)-menthol and (+)-neoisomenthol, respectively, by MMR and to (+)-neomenthol and (+)-isomenthol by MNR; the latter three monoterpenol isomers are minor constituents of peppermint oil.
Back