Knowledge of cannabisplants

Scientific information

Background knowledge of medical cannabis

The cannabis plant has a complex composition with many different chemical compounds. On this page, you can learn about the background knowledge of the cannabis plant, its chemical composition and medicinal production.


Taxonomy

The taxonomic naming of plants is a hierarchical way of grouping them into ordered categories such as families, genera, species and subspecies.

The genus 'Cannabis' belongs to the family 'Cannabaceae' (which also includes hops used in the brewing industry). There is no fully agreed taxonomic set of species names within Cannabis. Still, one option is to limit the classification to a single species called "Cannabis sativa L." with two subspecies: sativa and indica. This classification is partly based on structural characteristics, with Sativa varieties being taller and having longer and relatively thin leaves than the shorter, more broad-leaved Indica varieties.

Chemical composition - mainly THC content - has also been used in the attempt to establish a grouping of cannabis, and this has influenced the use of the names Sativa and Indica. Today, the terms are often used to describe the expected effect of a given cannabis strain, with Sativa expected to be more uplifting and energising and Indica more relaxing or soporific. This can make references to these subspecies confusing when it comes to both their botanical and therapeutic properties. Most varieties of Cannabis Sativa L. cultivated today are often referred to as 'hybrids' as they are largely a mixture of these historical subspecies, and the structure of the plant is not indicative of the content or composition of cannabinoids[1,2].


The plant

Cannabis has been cultivated for food (seeds), fibre (stems) and medicinal purposes (flowers) for thousands of years - see History for more information. For medical cannabis, the flowers are the most important parts of the plant as they contain the highest concentration of cannabinoids. It is a fast-growing plant (up to 6 meters tall in the wild) and naturally blooms once a year. However, the height can be limited, and flowering can be induced when grown in greenhouses by reducing the daily light interval to around 12-14 hours; this changes the plant's developmental stage from vegetative growth to flowering. Daily intervals of uninterrupted darkness cause the plant to flower. Cannabis plants are divided into male and female plants. The female flowers are used for medical cannabis as their cannabinoid content is higher[3].

The term "hemp" usually refers to cannabis plants that are grown for their fibres or seeds. The fibres are used in various products, such as textiles, rope, paper, insulation, masonry, carpets, etc.[1]. In Denmark, the THC content of cannabis plants categorised as hemp must be below 0.2%.


Chemical content

A total of 545 chemical compounds have been identified in cannabis plants. The most abundant and extensively studied class of secondary metabolites are the cannabinoids (>104), followed by terpenes (120), flavonoids (26) and steroids (11). The cannabinoids and terpenes are synthesised in glandular trichomes (specialised hairs), mainly found in female flowers[4]. The compounds are referred to as "secondary metabolites" as they are not essential for plant growth, development and reproduction but necessary for environmental survival. The cannabinoids are believed to protect plants from UV light and desiccation and play a role in the plant's defence against threats such as insects[5]. The terpenes give the plants scent and flavour. Flavonoids play various roles, from development and UV protection to defence and signalling between plants and microorganisms. They also give plants taste, smell and colour [6-9]. Terpenes give plants a scent and flavour. Flavonoids play various roles, from development and UV protection to defence and signalling between plants and microorganisms. They also give plants taste, smell and colour [6-9].


The flowers used to produce medical cannabis usually contain ~16-20% cannabinoids, 1-2% terpenes and <0.1% flavonoids[4]. Research has primarily focused on the cannabinoids Δ9 - tetrahydrocannabinol (THC) and cannabidiol (CBD), but there is increasing interest in the remaining secondary metabolites and their potential therapeutic benefits when combined (this is known as the 'entourage effect')[10,11]. Examples of lesser-known cannabinoids include tetrahydrocannabivarin (THCV), cannabinol (CBN), cannabigerol (CBG) and cannabichromene (CBC)[12]. The main terpenes are β-myrcene, pinene, limonene, linalool, β-caryophyllene and α-humulene[4].

Manufacturing medical cannabis

Growing medicinal plants in a reproducible way requires an appropriate quality assurance system and is typically done indoors to control factors such as humidity, lighting, diseases, insects, temperature, CO2, etc. To ensure a high and consistent quality of medical cannabis, the plants are grown and processed in accordance with GACP (Good Agricultural and Collection Practice) and GMP (Good Manufacturing Practice) guidelines. These guidelines are in place to allow producers to control and document all production steps that can affect product quality. This eliminates the risk of contamination, mix-ups and errors and ensures patient safety.

Cannabinoids are fat-soluble molecules with low solubility in water and can be extracted from the plant using solvents such as liquid CO2 and ethanol[6]. Whole plant extracts also contain terpenes and flavonoids. The cannabinoids synthesized in the plant are primarily in the carboxylic acid form (e.g. THCA and CBDA) and are heated for conversion to the neutral forms (THC and CBD) used in medicinal preparations[13]. Liquid extracts contain mainly the neutral forms of the cannabinoids because the extraction process includes a heating step, while the dried flowers need to be heated by patients to facilitate this conversion.

Beware of illegal cannabis-containing medicine

Unfortunately, illicitly sold cannabis-containing medicines, often called cannabis oils, CBD oils, etc., are widespread. These oils are typically sold unlawfully, mainly on the internet but also in physical stores. Sellers often claim that the products are legal or classified as dietary supplements. This is usually not accurate, and these oils cannot be compared to legal forms of cannabis-containing medicine, which are standardized and regulated.

There is significant uncertainty about how the illegal cannabis medicine is produced and what the products actually contain. The illegal products may contain substances different from what is indicated on the packaging, and the content can vary from bottle to bottle. The products and manufacturing process are not regulated, making it impossible to predict effects or side effects with certainty. It is dangerous, especially for individuals with illnesses, to ingest unknown substances, as neither the doctor nor the patient can anticipate how the unknown substances will affect the illness and the patient's other medications. Ultimately, there is a risk of worsening one's health.

For your own health, you should not purchase illegal medicine, and especially children should never be exposed to uncontrolled cannabis products.

Consult your doctor to determine the right treatment for you.

References

  1. Small, E. Cannabis : a complete guide. (CRC Press, 2016).

  2. McPartland, J. M. Cannabis Systematics at the Levels of Family, Genus, and Species. Cannabis and Cannabinoid Research 3, 203–212 (2018).

  3. Monthony, A. S., Page, S. R., Hesami, M. & Jones, A. M. P. The Past, Present and Future of Cannabis sativa Tissue Culture. Plants Vol. 10, Page 185 10, 185 (2021).

  4. Jin, D., Dai, K., Xie, Z. & Chen, J. Secondary Metabolites Profiled in Cannabis Inflorescences, Leaves, Stem Barks, and Roots for Medicinal Purposes. Scientific Reports 10, 1–14 (2020).

  5. Gülck, T. & Møller, B. L. Phytocannabinoids: Origins and Biosynthesis. Trends in Plant Science 25, 985–1004 (2020).

  6. Grof, C. P. L. Cannabis, from plant to pill. British Journal of Clinical Pharmacology vol. 84 2463–2467 (2018).

  7. Gonçalves, J. et al. Cannabis and Its Secondary Metabolites: Their Use as Therapeutic Drugs, Toxicological Aspects, and Analytical Determination. Medicines 6, 31 (2019).

  8. Andre, C. M., Hausman, J. F. & Guerriero, G. Cannabis sativa: The plant of the thousand and one molecules. Frontiers in Plant Science 7, (2016).

  9. Mathesius, U. Flavonoid Functions in Plants and Their Interactions with Other Organisms. Plants 7, 30 (2018).

  10. LaVigne, J. E., Hecksel, R., Keresztes, A. & Streicher, J. M. Cannabis sativa terpenes are cannabimimetic and selectively enhance cannabinoid activity. Scientific Reports 11, 8232 (2021).

  11. Russo, E. B. Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects. British Journal of Pharmacology 163, 1344–1364 (2011).

  12. Zagzoog, A. et al. In vitro and in vivo pharmacological activity of minor cannabinoids isolated from Cannabis sativa. Scientific Reports 10, 20405 (2020).

  13. Ladha, K. S., Ajrawat, P., Yang, Y. & Clarke, H. Understanding the Medical Chemistry of the Cannabis Plant is Critical to Guiding Real World Clinical Evidence. Molecules 25, (2020).

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