Essential oils in Lamiaceae

Abstract

The most common leaf spices in our latitudes belong to four plant families, of which the Lamiaceae or Labiatae (commonly known as the mint family) are presented exemplarily. Lamiaceae contain high concentrations of essential oils and are therefore favoured aromatic, medicinal and fragrant plants. Essential oils consist of very complex, highly volatile components that are produced in the chloroplasts, but also in the cytoplasm of plants via different metabolic pathways and are stored in special glandular scales or glandular trichomes. Components that belong to the group of terpenes are synthesized via the MEP pathway (methylerythritol phosphate pathway), which was only discovered and elucidated in the last decade of the last century. Phenolic components, however, are synthesized via the shikimic acid pathway, from which the aromatic amino acids tyrosine, phenylalanine, and tryptophan, which are essential for us, are also derived. The best-known commercially used Lamiaceae oils are rosemary oil, lavender oil, and peppermint oil, the main components of which belong to the monoterpene class of substances in each case. Rosemary oil also contains rosmarinic acid, which acts as an antioxidant and antiinflammatory compound in humans. Peppermint oils are used in the liqueur, candy, and cosmetics industries as well as in folk medicine (Japanese Medicinal Plant Oil) – for instance for inhalation in the event of a cold. As a treatment against digestive ailments, the leaves of lemon balm, mint and thyme are frequently used in teas. Rosemary, marjoram, oregano, and thyme are from the Mediterranean region and therefore prefer sunny locations in the herb garden.