Terpenes: What are they and what are they used for?

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Terpenes are the main constituents of essential oils and are responsible for the aromatic characteristics of cannabis.

Along with cannabinoids, terpenes illustrate a synergistic and/or entourage effect and their interactions have only been hypothesized in recent decades.

Hundreds of terpenes have been identified that allude to the sensory attributes of cannabis, contributing largely to consumer experiences and market price.

They also enhance many therapeutic benefits, especially as aromatherapy.

To shed light on the importance of terpenes in the cannabis industry, the purpose of this review is to morphologically describe the sources of cannabis terpenes

And explain the biosynthesis and diversity of terpene profiles in different cannabis chemovars.

The Terpenes

The energy required for the growth and development of Cannabis plants comes from photosynthesis, respiration and transpiration with O2, CO2, nutrients and water.

The energy is returned in the form of primary chemical ingredients that the plants later exploit.

These primary metabolites include carbohydrates, lipids, proteins, and nucleic acids.

However, during growth and reproduction cycles, plants can be challenged by stresses, including harsh environmental conditions or parasites and herbivores.

Plants then produce several groups of compounds called secondary metabolites that are used as defenses to these challenges.

For example, they may produce compounds that attract pollinators, including birds, to aid in the fertilization process or seed dispersal .

These compounds are produced in a variety of forms and are exploited for their biological functionality.

For example, alkaloids such as morphine and codeine in opium give psychoactive and pain-relieving activity to mammals.

Phenols and flavonoids found in the skin of fruits and berries possess antioxidant activity. Sulfur-containing compounds such as allicin in garlic can be used to reduce blood lipoglycerides and also have the ability to stimulate appetite.

The glycoside saponin in soap nuts can be used as a surfactant , and finally, terpenoids, which are main ingredients found in plants containing essential oils

Are used as food additives and some have psychoactive capabilities and aromatic characteristics such as those found in cannabis.

Terpenes are hydrocarbons with small isoprene units linked together to form chains, while terpenoids are oxygen-containing terpenes.

Three types of terpenes/terpenoids are usually found in the cannabis plant which are

  • (i) monoterpenes (10C) of two isoprene units
  • (ii) sesquiterpenes (15C) of three isoprene
  • (iii) diterpenes (20C) of four isoprene
  • (iv) triterpenes (30C) of six isoprene

To date, more than 200 volatiles have been reported from the different cannabis genotypes of which 58 monoterpenes and 38 sesquiterpenes have been characterized.

Among others, the main monoterpene components are

  • limonene
  • β-myrcene
  • α-pinene
  • linalool
  • traces of α-terpinolene
  • tran-ocimene (Figure 5b),
  • while the predominant sesquiterpenes are
  • E-caryophyllene
  • Caryophyllene oxide
  • E-β-farnesene and β-caryophyllene .

Cannabinoids are biologically synthesized from diterpene structures to form phenolic terpenoids, which account for almost a quarter of all metabolites.

Thus, the combination of terpenes provides the unique flavors to different strains.

The biosynthesis of these terpenes to secondary metabolites begins with common isoprenoid diphosphate (5C) precursors via two pathways, the plastidial methylerythritol phosphate (MEP) pathway and the cytosolic mevalonate (MEV) pathway .

These pathways regulate the different substrates available for terpene synthesis (TPS).

The MEP converts pyruvate and glyceraldehyde-3-phosphate (G3P) into 5-carbon bricks, isopentenyl diphosphate (IPP), and dimethyl diphosphate (DMAPP) into plastids .

The MEV pathway, on the other hand, alters three acetyl-CoA units into IPP, which is then isomerized into DMAPP by IPP isomerase in the cytosol.

IPP and DMAPP are condensed into longer-chain isoprenoid diphosphates that include geranyl diphosphate (GPP) and farnesyl diphosphate (FPP) .

These linear isoprenoid diphosphates are substrates for monoterpene synthases (mono-TPS) and sesquiterpene synthases (sesqui-TPS), respectively, which diversify these precursors through enzymatic modifications such as hydroxylation, dehydrogenation, acylation, and glycosylation into the different ranges of mono- and sesquiterpenes .

GPP is also a building block of cannabinoid biosynthesis

The cannabinoid biosynthetic pathway

Involves the process of chemically joining phenol with terpenes to form the non-activated acid forms that largely determine their potency and pharmaceutical properties including :

  • Cannabichromene (CBC)
  • Cannabidiolic acid (CBDA)
  • Cannabigerol (CBG)
  • Cannabinol (CBN)
  • Cannabidiolic acid
  • Cannabidivarin (CBDV)
  • Cannabidivarinic Acid (CBDVA)
  • Cannabinol (CBDV)
  • Cannabigerolic Acid (CBGA)
  • Cannabicyclic acid
  • Cannabicyclicol (CBL)
  • Cannabicyclic acid
  • Delta 8-THC
  • Tetrahydrocannabinolic Acid (THCA)
  • Tetrahydrocannabivarin (THCV)

These compounds, along with terpenes, are produced in the trichome structures available on the female cannabis flower.

The highest concentration of natural cannabinoids in cannabis are cannabidiolic acid (CBDA) and Δ9-tetra-hydrocannabinoic acid (Δ9-THCA).

Psychoactive metabolites such as delta 9-THC and non-psychoactive CBD are then activated through decarboxylation with heat treatments.

It is also aided by several factors such as storage time and the use of alkaline conditions .

Below are the important terpene groups in cannabis and their synergistic and functional properties.

The Monoterpenes of Cannabis

α-pinene and β-pinene inhibit acetylcholinesterase activity in the brain.

Therefore, it is claimed to aid memory and minimize cognitive dysfunction induced by THC intoxication .

The characteristic pine scent possesses antiseptic activity .

β-myrcene is known to have the analgesic effect of THC and CBD by stimulating the release of endogenous opioids through the α2-adrenergic receptor dependent mechanism .

Thus, if the level of myrcene is >0.5%, it can cause a “couch lock” effect while low levels of myrcene (>0.5% myrcene) can produce increased energy .

This compound offers the musky or hop-like fragrance with the functions of antioxidant and anticarcinogenic .

Although it has been postulated that the aroma limonene of citrus has a low affinity for cannabinoid receptors, this monoterpene increases the level of serotonin and dopamine, thus inducing the anxiolytic, anti-stress and sedative effects of CBD .

The floral fragrance of linalool could help anxiety through aromatherapy.

The Sesquiterpenes of cannabis

β-Caryophyllene, a spice (pepper) aroma, is the most available sesquiterpenoid in cannabis plants and extracts, especially after decarboxylation by heat.

It is a CB2 receptor agonist without psychoactivity .

It is also responsible for the anti-inflammatory effects of cannabis .

This sesquiterpene has also been shown to give gastroprotective, analgesic, anticarcinogenic, antifungal, antibacterial, antidepressant, anti-inflammatory, antiproliferative, antioxidant, anxiolytic, analgesic and neuroprotective effects.

The caryophyllene oxide that gives the scent of lemon balm is shown to have antifungal and insecticidal properties .

The chemovariants of cannabis

Depending on the varying compositions of terpenes, different “strains” of cannabis elicit different aromas with a greater link to product quality, retail price and consumer preferences .

The composition of cannabis terpenes is a seasonal variable.

The alteration of the proportion of terpenoids in cannabis is in accordance with the variety of cannabis

The part of the plant, the environmental conditions, the maturity and the method of analysis.

Different stages of cannabis growth could give significant variations in terpene composition.

The terpene profile of cannabis at the vegetative stage has been considered to have a much lower proportion of monoterpenes than at the flowering stage.

Apart from the variations and compositions of terpenes among different phenotypes, the molecular or biological modulated functions of terpenes are only effective when the terpene concentration in the complete cannabis extract is above 0.05% v/w .

To characterize the cannabis aroma profile of different chemovars, non-destructive and non-invasive solid-phase microextraction (SPME) was used to collect volatiles from samples .

This method favors a small sample size, and eliminates the use of organic solvents and, more importantly, allows the release of hundreds of volatile compounds from the samples .

Among the cannabis strains analyzed by Shapira, Berman, Futoran, Guberman and Meiri , five groups of chemotypes were identified according to the predominant terpenes:

  • (i) β-myrcene
  • (ii) α- and β-pinene
  • (iii) β-caryophyllene and limonene
  • (iv) β-caryophyllene
  • (v) terpinolene

In sensory perception of terpene profile differences among cannabis strains, two distinct descriptive groups were named.

The first group uniformly encompassed earthy, woody, and herbaceous, while the other group included the more frequent descriptors including citrus, lemon, sweet, and pungent.

In the past, identification of the terpene profile of cannabis was intended to improve canine training aids for illicit drug detection.

In the world of the cannabis industry, however

Terpenes play a vital role in differentiating the flavor and aroma that are specific to particular strains.

Some terpenes can enhance the effect of cannabinoids and synergize the feeling of relaxation, stress relief, energy boost and maintenance of concentration along with their underlying pharmaceutical functions.

Thus, a growing number of industries have shown interest in adding cannabis terpenes or terpenes of botanical origin to their CBD oils and edibles.

The estimated growth in this industry is expected to reach a market of 20 billion by 2024.

Success in this area may be challenged by a few limitations.

First, consumers believe that functionality and safety are truly linked to sources, perceived novelty, and most importantly, perceived benefits .

Additionally, full spectrum oil extraction consisting of a complete mix of natural cannabis terpenes is nearly impossible.

The most cost-effective way is to selectively separate the terpenes and include them back into the final products .

A number of terpene recovery techniques have been developed with or without solvents.

Essential oils are usually hydrodistilled extracts from cannabis trichomes that contain primarily terpenes or terpenoids.

Although most of the constituents remain intact during distillation, some monoterpenes may undergo chemical changes or are often lost due to the nature of the distillation process .

The other possible technique is steam distillation by passing dry steam through the cannabis inflorescence where the terpenes are volatilized, condensed and collected.

In addition, microwave-assisted extraction (MAE) can enrich the bioactive compounds.

MAE treatment using high irradiation power and relatively long extraction times has significantly increased the CBD content of the essential oil with a considerably high yield compared to conventional hydrodistillation techniques.

In Canada, for example, commercial production of the extract is achieved by extraction with solvents such as butane or supercritical fluid (SFE) with the restriction on product purity of no solvent contaminants .

The latter technique is known to give superior performance in the recovery of terpenes .

SFE has recently become a much preferred method for terpene recovery, largely because it allows lower temperatures to be used, leading to less deterioration of thermally labile components and is free of organic solvents .

A supercritical fluid is the substance at a temperature and pressure above its critical points

With no boundary between the liquid and gaseous stages.

At these points, the fluid is low viscosity with high diffusion properties to dissolve chemical molecules from the plant matrix.

Carbon dioxide (CO2) is generally used because it is nonflammable, relatively inexpensive, and nontoxic. Large amounts of terpene ingredients have been recovered by this method (i.e., up to 50%, 20%, and 10% of caryophyllene, humulene, and limonene, respectively, can be recovered compared to conventional methods) .

Conclusion on Terpenes

Recreational cannabis as a food ingredient has become more acceptable in a broader public context

In which cannabis terpenes have gained a great deal of industrial attention in recent years.

Terpene profiles not only embody the characteristics of cannabis genotypes, but their entourage effect with cannabinoids could enhance their medical functionality.

This review highlights the importance of understanding the chemistry of cannabis terpenes and provides descriptive categories of the profiles of different commercial cannabis strains.


Source : PMC