Cannabidiol, the constituent in Hemp which is known the world over for its pharmaceutical and medicinal properties. But how does it work to produce its favourable effects on the body? And, how do you extract CBD?
Hemp, scientifically known as Cannabis sativa, is well known across the world for its diverse use in the automotive, construction, bedding and, in its extracted form, CBD, for pharmaceutical industries. This annually reproductive plant, which originated from Eastern and Central Asia, is now cultivated across the world (1).
At present, the European Union is the third-highest producer of Hemp after China and Canada, with 25,000 hectares of cultivations (2). However, in the years to come, it is expected that the cultivation of Hemp will increase significantly, thanks to the rise of beneficially regulatory frameworks across the world. These frameworks help new companies to take advantage of the products of this multipurpose crop, with special emphasis on pharmaceutical and nutraceutical companies (3).
There are some downsides to Cannabis sativa, the most popular being that the raw material produces a compound called tetrahydrocannabinol (THC). THC is well known for its narcotic psychoactive properties and has led to Hemp being forbidden in many countries (4). Consequently, in order to avoid the illegal uses of hemp, only industrial hemp with less than 0.2% THC content can be cultivated in the USA, Europe, China and so on. However, there is a well-known and highly beneficial alternative; this is cannabidiol, known as CBD.
In this case, there are two major questions, what is cannabidiol (CBD)? And, how do you extract it from Hemp?
What Is CBD?
CBD was first isolated from cannabis in the late 1930s, over the next few years, its highly beneficial medical effects, especially so for epilepsy became apparent (5). After this, with increased scientific research, CBD became one of the key natural players helping a variety of conditions, including, as an anti-anxiety, helping the immune system, as an anti-nausea, an antioxidant, anti-inflammatory among many others (6). It is able to do this through the endocannabinoid system.
The endocannabinoid system is an endogenous signalling system which contains specific membrane receptors which, when CBD is present, causes a cascade of events in the human body. In this system, there are two main receptors, G-couple membrane protein-coupled cannabinoid receptors one and two (CB1 and CB2) (7).
In a nutshell, when CBD is present, it binds to CB1 and CB2, causing a cascade of processes which modulates different parts of the human body (8). These receptors are present in various concentrations in brain, central and peripheral nervous systems and tissues associated with the immune system. When CBD is present in these tissues, it excites and inhibits different parts of the brain, causing a cascade of processes, leading to its well-known beneficial effects on the body (9).
What is not as well-known is the fact that CBD is not actually produced in industrial hemp in large quantities. For some light chemistry, CBD is formed from a compound called cannabidiolic acid through a process called decarboxylation. This reaction can be spontaneous in the plant tissues in Hemp but in small quantities. However, through correct extraction and processing, the reaction is significantly sped up. In addition, as a result of its incredibly low boiling point, of around 180oC, CBD is able to be easily distilled (10).
Because CBD is so important for pharmaceutical and medical applications, it is important that we are able to extract it effectively, but how can we do that?
Types of CBD Extraction
Since the CBD extraction procedure, as well as how the material is pre-treated, plays a pivotal role in the content of CBD, it is important to look at both processes (11).
CBD Extraction, Pre-Treatment, Comparison of Dried and Fresh Hemp Material
Studies have shown that Hemp essential oils are significantly different between material which is left fresh and those which are dried. Fresh material produces higher essential oil amounts than that when the material is dried. This suggests that simply drying of the Hemp causes a number of the valuable compounds to be lost, as they are so volatile (12).
CBD Extraction, Pre-Treatment Using Microwave Heating
Simply, microwave heating uses microwave radiation to create the vibration of water, with an increase in temperature and evaporation, causing a release of volatile compounds, such as CBD, from the plant material. This has been touted as a “green” method, achieving higher CBD than just distillation alone (13). In fact, this method is able to extract more than twice the amount of CBD using Hemp, which has not gone through pre-treatment (13).
CBD Extraction, Pre-Treatment Using Crushing
When the plant material is simply ground into small sections for distillation, there is no real increase in the CBD obtained compared to not grinding at all. However, when this method is combined with microwave heating or oven heating, there is again nearly two-times the amount of CBD, which is distilled than not grinding or heating at all (14).
Supercritical CO2 Extraction
Supercritical CO2, or simply, a type of CO2 which has the characteristics of gas and liquid CO2, is one of the new top-dogs in the CBD world. In this process, CO2 acts as a solvent, along with heat, to separate the plant and to isolate the essential oils and oil-based bioactive compounds (15).
Hydrodistillation has been long used for the extraction of essential oils and bioactive compounds from plant materials. Hydrodistillation uses hot water to free bioactive compounds in the plant. Indirectly, cooling condenses the mixture and separates oil and bioactive compounds from the water. The essential oils and oil-based bioactive compounds are then dried (16).
Steam distillation is carried out by passing dry steam through the plant material whereby the volatile compounds are volatilised, condensed and collected into receivers. Stream distillation has been used in the extraction of essential oil for many years (17).
The Bottom Line
Hemp, one of the most diverse crops across the world, is well known in its ability to help numerous conditions in the human body, this is a result of cannabidiol. Cannabidiol acts through the endocannabinoid system to produce its highly beneficial effects, but how is it extracted from Hemp? There are a diverse amount of CBD extraction and distillation techniques, all of which have their own advantages and disadvantages. One thing is for certain, the way you process, extract and distil CBD has implications on how good it will be.