Terpenes occur naturally as organic compounds and are essential components of various plants, e.g., eucalyptus, peppermint, lemongrass, lemon tree, and thyme, contributing to their taste, smell, and color. They are considered the building blocks for many plants and essential oils; they are commonly found in perfumes and are widely used in food additives and aromatherapy. They are also called isoprenes because the structure is based on so-called isoprene chains. Terpenes have a wide variety of carbon structures and a small number of functional groups.
Terpenes and terpenoids
The difference between terpenes and terpenoids is that the former are simple hydrocarbons, while terpenoids contain other groups that may be made up of many chemical elements. However, you can use both terms commonly interchangeably. Terpenoids, also known under the term isoprenoids, form the largest group of known organic ingredients and comprise at least 20,000 different molecules.
Due to the wide distribution (currently, they know over 8,000 terpenes and over 30,000 of the closely related terpenoids), one cannot make general statements about terpenoids about their effects. They are considered to be the largest group of natural substances.
Their lipophilic nature makes terpenes fat and oil soluble, but they are poorly soluble in water. They also dissolve well in non-polar solvents such as chloroform or diethyl ether. The steam distillation technique mainly uses the terpenes mono-, sesqui- and limited diterpenes because they are steam-volatile. One can divide pure terpenes into mono-, sesqui-, di-, tri-, tetra-, and polyterpenes. The number of C5 blocks determines this subdivision. Monoterpenes contain 10 C atoms, sesquiterpenes 15, and diterpenes comprise 20 atoms. The terpenes triterpenes consist of 30, tetraterpenes of 40, and polyterpenes of 5x n C atoms.
The following substances belong to the group of terpenes or terpenoids:
Essential oils often owe their particular scent to the terpenes, mainly the volatile mono- and diterpenes. Citronellal, pinene, camphor, borneol, and eucalyptol are other terpenoid fragrances’ representatives. Below are some essential oils with the terpene they contain and their proportion.
|Mint oil||Menthol||up to 90%|
|Cumin oil||(+)-Carvone||up to 60%|
|Coriander oil||(S)-Linalol||over 70 %|
|Orange oil||(+)-Limonene||up to 97%|
The composition of the essential oils depends on the extraction process used (steam distillation or extraction).
Carotene is one of the coloring agents and is soluble in fat, not water. The best-known carotenes are lycopene and β-carotene. The latter is the precursor of vitamin A.
Most of these monoterpenes are water-soluble glycosides. Glycosides have pharmacological effects, primarily antimicrobial. For example, one finds iridoids in the devil’s claw root and verbena. Aucubin is an example of this, is contained in chaste berry herb, eyebright herb, and buckhorn, among other things.
Natural rubber belongs to this group, which is essential for rubber production. Especially from the beginning of industrialization until one discovered synthetic polymers (PVC, plastic), they played a significant role.
Steroids also belong to the group of terpenoids. Because they are lipophilic, they are often in high-fat plant parts. One can discover plant steroids in sunflowers, wheat, soybeans, sesame seeds, and grains.
Terpenes in Cannabis
So-called cannabinoids are created through complex chemical reactions in the cannabis plant; Terpenes are considered “assemblies.” A high number of terpenes often indicates high cannabinoid content, as terpenes are believed to be precursors to cannabinoids. Up to 120 terpenes can be found in the female hemp plant; however, many are only trace elements whose effects can be neglected. However, many of them have antibacterial, anti-inflammatory, and antiviral properties. The best-known representatives are caryophyllene and myrcene.
The following primary terpenes and terpenoids have also been identified in cannabis: limonene, pinene, linalol, cineol, nerolidol, and phytol, among others.
The specific smell of citrus fruits is due to the monoterpene limonene. One often uses D-limonene in food and perfume production as a flavoring; in its isolated form, it smells strongly of oranges. One also uses it in alternative medicine to alleviate heartburn and gastric acid reflux. Another application area for d-limonene is cleaning products: it can dissolve oils and other lipids and remove paint. Since many existing terpenes may be lost during extraction, d-limonene is added to cannabis extracts as a flavor enhancer.
The monoterpene myrcene is the most abundant in cannabis. Myrcene makes up 60% of the essential oils found in some cannabis strains. But not only in cannabis, you can find this substance; also in wild thyme, hops, bay leaves, lemongrass, and verbena. The aroma is perceived as resinous, slightly metallic, and herbaceous; high concentrations are very intense. In laboratory tests with rats, one tested myrcene for its pharmacological effects; they could demonstrate an analgesic effect. The terpenes limonene and the terpenoid citral (found in many citrus fruits) produced a sedative and motor-relaxing impact in mice.
Pinene is a monoterpene; you can divide it into two isomers (α-pinene and ß-pinene). In addition to cannabis, one can also discover it in sage, mugwort, pine, and eucalyptus. Olive, rosemary, and bergamot contain α-pinene (nature’s most common terpene), while you find ß-pinene in hops and cumin. In humans, pinene also acts as a bronchospasmolytic in small doses and has anti-inflammatory, antibacterial, and antibiotic properties.
The monoterpenoid linalol, which occurs in hundreds of plant species, is in cannabis, cinnamon, birch, mint, and many types of citrus. You can locate the terpenoid (“left” enantiomer) known as S-linalol in coriander and sweet orange, which provides a sweet, floral scent. The “right” enantiomer, known as R-linalol, is in lavender and basil and has a more woody aroma. One values linalol for its medically significant effects as an anxiolytic: an anxiety-reducing drug. In addition to laboratory tests on rats, which have demonstrated a sedative and motor-relaxing effect, lavender, for example, has been used as a tranquilizer for thousands of years.
The naturally occurring monoterpenoid is cineole. You can find it not only in cannabis but also in true laurel, eucalyptus, basil, and sage. This terpenoid also exhibits antiseptic, antibacterial, and anti-inflammatory effects.
The terpene B-caryophyllene found in cloves, rosemary, and hops can act as a selective antagonist of the CB2 receptor. To date, one doesn’t know other terpenes or terpenoids that could affect the CB receptors. Caryophyllene oxide is the substance in the hemp plant that drug sniffer dogs detect. Another terpenoid is phytol, which insects use to deter predators. One finds it also in households in some detergents and soaps.
Found in ginger, jasmine, and orange blossom oil, the terpenoid nerolidol has a fresh and woody scent. Among other things, there is research as a transport substance for transdermal drug administration.
Differences between cannabis types
Depending on the cannabis strain, the concentration of terpenes and terpenoids is very different. However, various environmental conditions during the plant’s growth phase result in different concentrations of terpenes and terpenoids, even in cultivars and clones of the same individual.
One believes that the terpenes and terpenoids in cannabis cause the different medicinal effects in each cannabis subtype; however, the health benefits have not been thoroughly researched.