Extraction of Acidic Cannabinoids

Most consumers are seeking tetrahydrocannabinol (THC) for its intoxicating effects. However, as medical research expands within the cannabis sector, manufacturers and consumers are finding value in the acidic forms of cannabinoids. It is only possible to experience acidic cannabinoids through ingestible or topical methods of administration because heat will convert the acidic cannabinoid into the neutral form. In this article, we explore how cannabis extraction technology can preserve the acidic cannabinoids in the process.

In the raw form of cannabis, the cannabis plant mainly produces acidic forms of cannabinoids. Cannabigerolic acid (CBGA) is the precursor to most of the cannabinoids produced by the cannabis plant (1). Tetrahydrocannabinolic acid (THCA) is another common and naturally abundant cannabinoid found in the cannabis plant. When cannabis is heated, acidic cannabinoids such as THCA undergo decarboxylation. For example, THCA converts to tetrahydrocannabinol (THC), the psychoactive compound that produces the well-known cannabis “high.” THCA, however, is non-psychoactive. There is limited research on the physiological differences between consuming acidic versus decarboxylated cannabinoids. However, there is growing evidence that acidic cannabinoids like THCA or cannabidiolic acid (CBDA) have unique medical benefits and bioavailability.

Why Create Acidic Cannabinoid Products?

Smoking is the most common method of administration in cannabis, but acidic cannabinoids cannot be consumed by smoking due to triggering decarboxylation. Instead, the acidic cannabinoids can be extracted and infused in edibles, topicals, and can even be vaped at lower temperatures. With a variety of consumption methods, acidic cannabinoids are growing in availability and popularity. This is especially true of THCA, which shows promising medical benefits (1,2). Some potential medical benefits of THCA include:

• Anti-inflammatory: THCA has been shown to have anti-inflammatory properties, which could be beneficial for people with conditions such as arthritis, inflammatory bowel disease (IBD), and multiple sclerosis (MS).
• Anti-nausea: THCA has been shown to have anti-nausea properties, which could be helpful for people undergoing chemotherapy or experiencing nausea and vomiting from other causes.
• Neuroprotective: THCA has been shown to have neuroprotective properties, which means it may help protect the brain from damage or degeneration. This could be beneficial for people with conditions such as Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis.
• Anti-spasmodic: THCA has been shown to have anti-spasmodic properties, which means it may help reduce muscle spasms and cramps. This could be beneficial for people with conditions such as multiple sclerosis, spinal cord injuries, and cerebral palsy.
• Appetite stimulation: THCA has been shown to have appetite-stimulating properties, which could be helpful for people with conditions that cause a loss of appetite, such as cancer or HIV and AIDS.

It’s important to note that more research is needed to fully understand the potential medical benefits of THCA and how it can be used to treat specific conditions. Until that research is available, consumers and medical patients are relying on manufacturers and leading cannabis scientists to offer insights into what products may support them on their cannabis journey.

Manufacturers are utilizing extraction technology to extract and purify THCA for the purpose of producing cannabis products for the medical market or for the novelty concentrate market. The novelty cannabis concentrate market has contributed to the growing popularity of THCA as products like “diamonds and sauce” take up market share. These products give consumers an opportunity to vaporize THCA before it converts to THC, however, most consumers are heating these extracts to temperatures at which point decarboxylation does occur. Other acidic cannabinoids do not seem to be of particular interest to recreational users.

How to Selectively Extract Acidic Cannabinoids?

Figure 1 shows the differences between cannabinoids as well as acidic and neutral forms. Each of these compounds varies in molecular weight, polarity, size, and so on. Because of these differences, these compounds have different solubility and behavior during extraction. Most of the common solvents are non-polar. Carbon dioxide or hydrocarbons, for example, are non-polar solvents. Cannabinoids are also relatively non-polar, so polarity is not a lever that can be pulled to selectively extract acidic cannabinoids. Instead, manufacturers can start with plant material that is rich in THCA. The plant’s trichomes are most full of acidic cannabinoids late in the flowering stage and at peak harvest. If the plant is not dried or cured in the ideal conditions for preservation of the chemical profile, then degradation can occur of both the cannabinoids and terpenes. Some cultivators and extract manufacturers skip the drying and curing phase by freezing the cannabis flowers immediately upon harvest. In doing so, the acidic cannabinoids are preserved and undisturbed.

Acidic cannabinoids, especially from freshly frozen or freshly harvested cannabis flower, can be extracted from the plant using CO2, hydrocarbon, or ethanol. They can also be extracted using physical separation techniques such as the hash making process. In any of these processes, extraction technicians rely on optimal extraction parameters for these cannabinoids while minimizing the exposure of the extract to heat. Once extracted, the cannabinoids can be further purified using winterization or another filtration technique to remove any waxes and other undesirable fractions from the solution. Last, crystallization is encouraged by either gently heating or cooling the refined extract to initiate nucleation of the acidic cannabinoid crystals. Heating or cooling is based on the type of solvent that was used to extract the cannabinoids. Multiple nucleation and filtration steps can be used to increase the purity of the acidic cannabinoid fractions. Alternatively, chromatography can be used to separate the cannabinoids and other compounds from the extract mix. However, chromatography is much more expensive and more challenging to scale.

Conclusion

Products dominant in acidic cannabinoids may never achieve the same market share as the active compounds, like THC. However, consumer preferences and needs are becoming more diverse as cannabis becomes more accessible throughout the country. Acidic cannabinoids will continue to attract consumers seeking medical benefits or new experiences. As extraction technology develops, selectivity will improve, and unique chemistry will continue to find its way into the marketplace. Acidic cannabinoids are ripe for the picking.

References

1. Pellati, F.; Borgonetti,V.; Brighenti, V., Biagi, M.; Benvenuti, S.; Corsi, L.; Cannabis sativa L. and Nonpsychoactive Cannabinoids: Their Chemistry and Role against Oxidative Stress, Inflammation, and Cancer, Biomed Res Int., December 2018, doi: 10.1155/2018/1691428. PMID: 30627539; PMCID: PMC6304621.
2. Ben-Cnaan, E.; Permyakova, A.; Azar, S.; Hirsch, S.; Baraghithy, S.; Hinden, L.; Tam, J.; The Metabolic Efficacy of a Cannabidiolic Acid (CBDA) Derivative in Treating Diet- and Genetic-Induced Obesity, Int J Mol Sci., May 2022, 23 (10). doi: 10.3390/ijms23105610. PMID: 35628417; PMCID: PMC9144717.

About the Columnist

Lo Friesen is the founder, CEO, and Chief Extractor of Heylo. With a background in chemistry and clinical research, Lo was inspired to explore cannabis as a medicine and to enter the emerging industry. She joined Eden Labs, a leading CO₂ extraction equipment manufacturer to support and expand a Research and Development department. There she managed the development of their latest and greatest CO₂ extraction system. In 2017, after working with Eden Labs and another cannabis processor, Lo launched Heylo with a mission to help people get more out of life with cannabis.

How to Cite this Article:

Friesen, L., Extraction of Acidic Cannabinoids, Cannabis Science and Technology, 2023, 6(3), 14-17.