Acidic versus non-acidic form

In the hemp plant, the cannabinoids are mainly present in acidic form. This means that each cannabinoid molecule has an acid group attached to it. They are naturally formed by the plant in this way. In the living plant and in well-preserved dry material, more than 90% of the cannabinoids are normally present in acidic form.

Fig. 1: Decarboxylation of CBDA to CBD

Acidic versus non-acidic form

In the hemp plant, the cannabinoids are mainly present in acidic form. This means that each cannabinoid molecule has an acid group attached to it. They are naturally formed by the plant in this way. In the living plant and in well-preserved dry material, more than 90% of the cannabinoids are normally present in acidic form.

Cannabinoids can undergo a reaction called decarboxylation, which means that they lose this acid group. This chemical reaction is a long-term process, but it can be greatly accelerated by heating. This is the case, for example, when a cannabis product is smoked or cooked long enough.

The regulated Δ9-THC molecule has been shown to be more active in the non-acidic form (Lewis et al., 2017). Thus, in the case of regulations, the non-acidic form is assumed when determining and indicating the total cannabinoid content of hemp products.

In addition to THC, hemp contains more than 130 cannabinoids. For the sake of clarity, reference is always made below to the decarboxylated (non-acidic) form of the cannabinoids.

cannabinoids

CBD, together with Δ9-THC, is one of the two main cannabinoids of the hemp plant and was first isolated and identified in 1940 by the American chemist Roger Adam and his colleagues (Adams et al., 1940).

In contrast to Δ9-THC, CBD has no psychoactive effect (Pisanti et al., 2017). If a sufficiently large proportion is present, CBD can also weaken or even suppress the psychotropic effect of Δ9-THC (Niesink and van Laar, 2013; Schubart et al., 2011).

Fig. 2: CBDA and CBD molecules.

Δ9-THC, along with CBD, is one of the two main cannabinoids of the hemp plant. It was first isolated and identified in 1964 by Israeli researchers Dr. Yechiel Gaoni and Prof. Raphel Mechoulam (Gaoni and Mechoulam, 1964).

Δ9-THC has a strong psychotropic effect and has therefore been classified as a regulated substance by numerous national and international regulations. In Switzerland, the legal limit of Δ9-THC is mainly regulated by two ordinances of the Federal Office of Public Health (FOPH) and depends on the type and name of the product:

  • 1% in non-edible hemp products (e.g. tobacco substitutes) according to regulation 812.121.11
  • 0.00002 to 0.003% in edible products (depending on the type of product) according to Regulation 817.022.15.

Fig. 3: Delta-9-tetrahydrocannabinol

CBC is a cannabinoid commonly found in cannabis and is widely considered non-psychotropic (Russo, 2011; Turner et al., 1980).

In indoor-grown cannabis, CBC is usually present in the same amounts as THC, but in outdoor-grown cannabis, it can reach considerably higher concentrations (up to 5 times more than THC).

Fig. 4: Lorem Ipsum

CBG, which is considered a “precursor” cannabinoid, is the first to be produced by the hemp plant and is subsequently converted into other cannabinoids such as CBD and Δ9-THC.

Fig. 5: Lorem Ipsum

Δ8-THC has a similar molecular structure to Δ9-THC, but is said to have a significantly lower psychotropic effect (according to the American National Health Institute).

It is usually found in CBD-rich hemp as a breakdown product of CBD, usually at a concentration of 1-2% of the total CBD.

Fig. 6: Lorem Ipsum

CBN is a degradation product of Δ9-THC.

Fig. 7: Lorem Ipsum

CBL is a breakdown product of CBC.

Fig. 8: Lorem Ipsum

The Varin group of cannabinoids includes a number of cannabinoids with a very similar structure to the molecules listed above (CBD, THC, CBD, etc.), but with a shorter alkyl chain (like a shorter “tail”, see image above)

Usually they occur in smaller quantities in hemp
than the other cannabinoids.

Fig. 9: Lorem Ipsum

terpenes and terpenoids

Terpenes are an important family of chemicals produced by hemp plants, as well as many other plants and animals. They are aromatic molecules that give different types of hemp their characteristic scent and taste. To date, more than 200 different hemp terpenes have been identified.

Fig. 10: Isoprene, the basic unit of terpenes.

These molecules are hydrocarbons that are all made up of the same basic unit: isoprene. According to the number of isoprene units they are made of, terpenes are divided into subgroups: monoterpenes (2 units), sesquiterpenes (3 units), diterpenes (4 units), etc.

Fig. 11: Example of a monoterpene

The hemp plant also produces a large number of substances called terpenoids. These are the same hydrocarbons as terpenes, but with functional groups that usually contain oxygen (eg alcohol, acids, ketones, esters...). They are often called "oxygenated terpenes". Strictly speaking, cannabinoids are diterpenoids (ie they consist of 4 isoprenes with additional functional groups).

Fig. 12: Example of a sesquiterpene

Some of the different terpenoids are considered to be important precursors for all other terpenes, terpenoids and hence cannabinoids. This means that the hemp plant first forms these precursors and then modifies them to form the compounds described above (see next section).

Fig. 13: Examples of terpenoids

terpenes and terpenoids

Terpenes are an important family of chemicals produced by hemp plants, as well as many other plants and animals. They are aromatic molecules that give different types of hemp their characteristic scent and taste. To date, more than 200 different hemp terpenes have been identified.

These molecules are hydrocarbons that are all made up of the same basic unit: isoprene. According to the number of isoprene units they are made of, terpenes are divided into subgroups: monoterpenes (2 units), sesquiterpenes (3 units), diterpenes (4 units), etc.

The hemp plant also produces a large number of substances called terpenoids. These are the same hydrocarbons as terpenes, but with functional groups that usually contain oxygen (eg alcohol, acids, ketones, esters...).

They are often referred to as "oxygenated terpenes". Strictly speaking, cannabinoids are diterpenoids (that is, they consist of 4 isoprenes with additional functional groups). Some of the various terpenoids are considered to be important precursors for all other terpenes, terpenoids and thus cannabinoids. This means that the hemp plant first forms these precursors and then modifies them to form the compounds described above (see next section).

synthesis of cannabinoids

The precursor geranyl pyrophosphate (GP) is considered the starting material for all other terpenes. The hemp plant also contains two other precursors, olivetolic acid (OS) and divarinolic acid (DS), which then react with GP to form CBG and CBGv respectively. All other cannabinoids found in hemp are then formed from these two "cannabinoid precursors".

Fig. 14: Synthesis pathways of terpenes and cannabinoids in hemp.

Fig. 15: Lorem Ipsum

ratio of cannabinoids

The ratio of the content of the various cannabinoids depends primarily on genetics and environmental factors. This particularly concerns the CBD: Δ9-THC ratio, which lies within a very narrow range of values.

Three main groups of hemp can be identified:

– The CBD dominant strains with a CBD:THC ratio generally between 20:1 and 32:1. Some strains can have a ratio as low as 15:1, but these are rarely found.

– the balanced strains with a CBD:THC ratio between 1:1 and 4:1.

– the THC-dominant strains with a CBD:THC ratio well below 1:50 to 1:200.

Only CBD-dominant strains are likely to contain a low enough THC content to be considered legal. Because the CBD:THC of CBD-dominant strains is genetically determined and is quite different from the other two types, it can be predicted by analyzing young plants. It falls within a fairly narrow range, as shown in the adjacent diagram.