By Dr. Arno Hazekamp, Cannabis researcher, Leiden University, The
1) The chemistry of cannabis tea.
How did I get involved in the chemistry of cannabis tea? Well, it all started in
2001. Not long after finishing my Master’s degree in phytochemistry (the
chemistry of medicinal plants), my professor one day suddenly asked me how I
would feel about doing a PhD on the medicinal use of cannabis. I am sure you
can imagine my surprise. That year, without me noticing it, the Dutch government
had decided that there was enough reason to consider cannabis, under certain
conditions, a medicine. Because many patients already used street cannabis in
the form of dried flowers (buds) this was chosen as the starting point for the
Dutch medicinal cannabis program as well: dried flowers, also known under their
official pharmaceutical name, cannabis Flos, but of pharmaceutical quality and
with always the same chemical composition. An experienced plant grower
(Bedrocan BV) was contracted for production, and the program became a fact in
2001. Figure 1 shows an example of the product that is currently available in the
As a scientist, my task would be to help develop this herbal material into
something ‘better’, something more advanced, so that cannabis could be fully
introduced into the world of modern medicine. After all, the fact that cannabis
may have a positive effect in some patients was not enough. What about the
administration form, the dose, the variety of cannabis needed for which medical
condition? Those are issues that need to be resolved for any medicine on the
market, and the Dutch government certainly did not want to make exceptions for
this unconventional herbal product called cannabis. The directive of the Health
Ministry therefore was clear: The Netherlands, as the first country in the world,
would make herbal cannabis available to patients on prescription, if the
pharmaceutical industry and academic researchers would work on developing
modern cannabis-based drugs. Herbal cannabis was simply a temporary and
practical solution in order to help chronically ill patients until the job was done,
and the cannabis-pill was developed. In any other country, medical users were
not as fortunate as they had to wait until such cannabis medicine would have
been developed. Something most of them are still waiting for today.
Some people may believe that herbal cannabis does not have a future in modern
medicine, simply because it is too ‘rough’. After all, real medicines look different:
they come in precise doses, have a fixed composition, and the administration
form is clear: take 2 of the blue pills a day, and come see the doctor in a few
weeks. Indeed, there is a lot to be desired with the current way cannabis is used
as a medicine. When you ask for your favorite cannabis strain, are you certain
you always get the same product in terms of its chemical composition? My own
research among Dutch coffeeshops clearly indicates this is not the case. And
what about contaminations such as pesticides, growth-enhancers, heavy metals,
microbes? As a patient, can you really afford to be exposed to such risks, when
the only thing you want to do is get better? These are obvious reasons to further
develop medicinal cannabis into a more safe and reliable product.
Of course, the idea of the Dutch program was that the active ingredients of the
cannabis plant would be identified, isolated, and put into nice little pills. Just like it
has happened with so many other medicinal plants in the past: opiates from the
poppy plant, aspirin from willow bark, or anti-malaria drugs from a variety of plant
species such as Artemisia. However, what if such a product would be based
directly on the herbal cannabis that many patients prefer to use today? Is that a
real possibility? I believe it certainly may be, but only if we can come up with a
method of administration that is reliable, reproducible and safe. After all, not
many doctors feel comfortable with just sending patients home with some bud,
and let them decide themselves whether to smoke it, bake it, or even juice it raw.
During my ten years of cannabis research, I have mainly focused on helping to
answer such questions, related to quality control, administration forms and
dosing. Besides studying tea, I have also focused on vaporizing, smoking,
extracts and edibles. According to my studies, cannabis tea is an easy and
reliable way to use medicinal cannabis in its herbal form, if a few simple
guidelines are followed. Please follow me through this chapter as I will introduce
you to the exciting chemistry of cannabis tea.
2) Cannabinoids and terpenes: the active ingredients of cannabis
The cannabis plant has a long history as herbal medicine, and contains a large
variety of pharmacologically interesting ingredients. With more than 500 known
constituents, Cannabis sativa is chemically one of the best studied plants in
science. But because most of these constituents have not yet been properly
characterized for their therapeutic activity, the cannabis plant could be called a
“neglected pharmacological treasure trove” [Mechoulam 2005].
The most interesting among the cannabis constituents are found in the
secretions of glandular hairs, which are also called trichomes or ‘crystals’,
because of their sparkly appearance. Such trichomes (see figure 2) can be found
all over the male and female plants, but they are particularly concentrated around
the female flowers. The dried resin obtained from the flowers is generally known
as hash, or hashish. This is the source of the most important bioactive
components of the cannabis plant; the ‘cannabinoids’.
Cannabinoids are generally considered to be the main biologically active
constituents of the Cannabis plant, and they are unique to the cannabis plant;
they are found nowhere else in nature. The most famous of all cannabinoid of
course is delta-9-tetrahydrocannabinol, or THC, which is responsible for the
psychedelic effect of the cannabis plant. But there are many more: already 70
different cannabinoids have been identified by researchers, and the number is
still growing. The many cannabinoids are chemically very closely related to each
other, but nonetheless have very different biological and medicinal properties.
THC is the only one of them with significant psychoactive properties.
Although many cannabinoids are known, not all of them are found in all cannabis
products. After all, they were identified over several decades of cannabis
research, studying many different cannabis products, and different and
sometimes rare types of cannabis plants from a variety of origins and qualities.
Not surprisingly, there can be an enormous variation in the relative content of
cannabinoids, and this is part of the reason so many different varieties of
cannabis exist. There is however a handful that you will most likely encounter to
some degree in most cannabis varieties: THC, CBD (cannabidiol), CBN
(cannabinol), CBG (cannabigerol) and CBC (cannabichromene). See figure 3 for
the chemical structures of these compounds.
Traditionally, there has been a dominant focus on THC because cannabis was
mainly used and studied as a psychoactive drug. The main question we asked
ourselves was simply: how high does it get me? But now cannabis is increasingly
embraced as a medicine again, it is time to change that focus and to broaden our
scope. A better understanding of the non-psychedelic components of cannabis
clearly is a step in the right direction. For example, CBD is studied for its anti-
psychotic and anti-tumor properties, while THC-acid (see below) is a potent
regulator of the immune system.
So now we discussed the cannabinoids as an important group of therapeutic
compounds. But have you ever wondered what gives cannabis its distinct smell?
The answer is not the cannabinoids, because they have no smell at all. In fact,
the smell, taste, and perhaps some of the medicinal properties of cannabis come
from another class of compounds called the ‘terpenes’. Together with the
cannabinoids, they are found in high concentrations in the resin excreted by
cannabis flowers. Terpenes are not only found in cannabis, but in many fragrant
plants all over the world. Terpenes have a lot of different medicinal effects,
including anti-bacterial, anti-inflammatory, anti-asthmatic, and relaxing properties.
Examples of such terpenes are: pinene, humulene, myrcene and beta-
Because of centuries of breeding and selection, a large range of cannabis
varieties has been developed, which are commonly distinguished through the
use of popular names such as ‘White Widow’, ‘Northern Lights’, ‘Amnesia’ or
‘Haze’. Already, over 700 different cultivars have been described [Snoeijer, 2001]
and many more are thought to exist. However, it is unclear whether or not these
names reflect any relevant differences in chemical composition. There is a lot of
scientific interest in understanding why varieties are different, and what
constituents are responsible for this. The cannabinoids and terpenes are the
most likely candidates.
3) How cannabinoids work
Now you know that the cannabinoids are widely considered as the main
therapeutic ingredients of cannabis, doing most of the important work. The
terpenes are generally seen as having an additional supporting role. According to
many medical users, this is synergy or holistic medicine at its best. But an
important question remains; how do cannabinoids exert their therapeutic effects,
and under what conditions?
Until quite recently, the biochemical mode of action of cannabinoids was
unknown. Initially it was assumed that cannabinoids such as THC simply dissolve
in cell membranes in the brain, thereby disrupting the function of brain cells,
similar to the way alcohol makes you feel drunk. Then something revolutionary
happened; around the 1990’s, the human endocannabinoid system was
discovered, and we learned that many of our own bodily functions are controlled
by cannabis-like substances in our brain, immune system and other organs. It
was also shown that this combination of cannabis-like substances
(endocannabinoids) and its natural binding sites in the body (cannabinoid-
receptors) was present in every imaginable animal life form, from cats and mice
down to puffer fish and even sea urchins. This clearly showed the evolutionary
importance of such a system for basic survival (and thriving?) of species.
Currently two types of cannabinoids receptors are known: The CB-1 receptor is
predominantly present in the central nervous system, mainly in those brain
regions that correspond with well-known effects of cannabis consumption: sleep,
appetite, time perception, etc. Overstimulation of CB-1 results in feeling high or
stoned. A second cannabinoid receptor (CB-2) is present mainly in the immune
system where it can influence pain, inflammation and tissue damage.
Based on what we have learned so far, the endocannabinoid system is involved
in many physiological functions and might be related to a general stress-recovery
system. This variety of effects was concisely summarized by the Italian scientist
DiMarzo, who stated that endocannabinoids help you 'feel less pain, control your
movement, relax, eat, forget (posttraumatic), sleep, and protect your neurons'.
Scientific studies clearly show that endocannabinoids play an important role in
keeping our bodies balanced, especially during a state of illness. External
cannabinoids, present in the cannabis plant, are able to interact with our
endocannabinoid system in multiple ways. But is that always a good thing? In
some cases (depending on e.g. cannabis variety, dose, and administration form),
the effects may be therapeutic, but when too much is consumed a state of
intoxication will occur. In some way you could say that recreational users of
cannabis are purposely overdosing a medicinal substance. By looking at the
issue in this way, it may be easy to see the difference between medicinal use
and drug use.
4) The chemistry of cannabis tea
So now you think you know something about cannabis chemistry, right? But what
if I told you the cannabis plant does not produce a single molecule of THC? And
yes, that includes your favorite strain, too! The cannabis plant does produce a
group of chemicals known as cannabinoids, which have truly unique medicinal
properties. What I did not mention yet is that those cannabinoids are not actually
produced in the form we commonly assume. THC and CBD are the most obvious
examples of this; also known as neutral cannabinoids, those are the chemicals
scientists have most closely studied, and users have learned to appreciate for
reasons both medicinal and recreational. However, the cannabis plant actually
produces all of its cannabinoids in the form of so-called acidic cannabinoids,
which are chemically distinct versions of the neutral cannabinoids with straight-
forward names like THC-acid and CBD-acid. Sounds complicated, but it is crucial
for understanding the unique properties of cannabis tea.
Let me explain. If sufficient heat is applied, the acidic cannabinoids will turn into
their neutral counterparts. So when cannabis is burned for smoking, baked for
edibles, or boiled for tea, non-psychoactive THC-acid turns into THC, CBD-acid
turns into CBD, and so on for all other cannabinoids. This process, called
decarboxylation, is visualized in figure 4. It also spontaneously takes place in
aging cannabis samples as a result of storage and exposure to light, but at a
much slower rate. Until recently, acidic cannabinoids were generally considered
the ‘inactive’ forms of cannabinoids. After all, they can’t get you high, and there is
almost no trace of them in cannabis smoke. Since both consumers and
researchers have focused mainly on smoking as a method of delivery, most of us
were hardly aware that the acidic cannabinoids even existed. But smoking is not
the only way - or the best way - to ingest your medicine. During my studies I
discovered that an average cup of cannabis tea contains about 5 times more
THC-acid than THC, even after 15 minutes of boiling. The reason is that boiling
water is not nearly as hot as the heat applied for baking brownies, or
smoking/vaporizing of cannabis. Cannabis tea should therefore not just be
considered as a weak administration form of THC (which it is), but rather as an
entirely different medicine, because of the presence of high amounts of acidic
So what can these ‘acids’ do for you? Well, potentially a lot, because an
increasing number of studies show that they may have important medicinal
properties. For example, CBD-acid has a potent antimicrobial activity, and shows
promising anti-inflammatory effects. THC-acid was found to have a potent effect
on the human immune system (Verhoeckx 2006), and may be studied in clinical
trials soon. And perhaps most interestingly, some acidic cannabinoids may slow
the growth of certain cancers, at least in laboratory tests.
Now you know the whole story of the chemistry behind medicinal cannabis,
5) The therapeutic potential of cannabis
Almost no plant has been studied as much as the cannabis plant; more than
10.000 papers have been published describing various aspects of Cannabis as a
biologically active plant. Nonetheless, it is hard to think of a medical topic that
can so strongly divide the research community as the medicinal use of Cannabis.
It may even be stated that Cannabis is the most controversial plant in the history
of mankind. But imagine Cannabis sativa would be discovered today, growing in
some remote spot of the world, it would be hailed as a wonder of nature; a new
miracle plant with the potential to treat anything ranging from headaches to
neurological disorders to cancer.
Although herbal cannabis is currently classified by international regulations as a
“dangerous narcotic with no accepted medicinal value”, that is not exactly true for
some of the major components of the cannabis plant. In fact, there are several
components derived from the cannabis plant that have an accepted and very
interesting potential as a medicine. Marinol® is an oral capsule that contains a
synthetically produced version of the natural THC. It has been approved for
treating nausea and vomiting in related to cancer and AIDS, and for stimulation
of appetite in severely underweight patients. Another product, called Sativex®,
makes use of the combined effects of THC and CBD extracted from cannabis
plants. It is mainly targeted at pain and spasticity in MS. Some other medication
is based on compounds that are modeled after plant cannabinoids, but have a
slightly different chemical structure. An interesting example is ajulemic acid, a
very strong pain killer based on THC, but without the psychotropic effects.
Herbal cannabis itself, in its native plant form, would be hard to patent, which is
the main reason that pharmaceutical companies have not spent too much effort
on this. Nonetheless, the experiences of (large groups of) patients have been
important for the development of cannabis-based medicines. Clinical studies with
single cannabinoids or whole plant preparations have often been inspired by
positive anecdotal experiences of patients using crude cannabis products for
self-treatment. The antiemetic, appetite enhancing, analgesic and muscle
relaxant effects, and the therapeutic use in Tourette’s syndrome were all
discovered or rediscovered in this manner. If herbal cannabis wants to become a
real and legitimate medicine some day, it needs to be studied in much more
detail. But for the time being edibles, tea, and vaporizers may very well be able to
fill the void.
6) Cannabis tea and an introduction to its history.
In Jamaica, which is sometimes quoted as the country with the highest
consumption of cannabis, the different uses of cannabis have been thoroughly
studied [Rubin and Comitas, 1975]. Although cannabis, which is locally known as
ganja, is mostly consumed by smoking, drinking of ganja tea is common among
non-smokers and is consumed even by young children and the elderly. The tea is
attributed various therapeutic and prophylactic qualities and is used as a remedy
for i.e. fever, cold and stress.
Also around Europe, hemp containing foods, including leaves for tea preparation,
are widely available. Often these products are associated with health. Although it
is legally not permitted, herbal hemp leaves used for tea have been found to
contain relatively high THC levels (up to 5000 mg/kg) and significant
concentrations were determined in the corresponding tea infusions. Potentially,
any health claims based on the consumption of such teas might therefore be
attributable to its (unintended) content of THC or other cannabinoids.
Until recently, virtually no standardized studies had been performed with tea
preparations of cannabis. The single large scale field study which includes the
use of cannabis tea [Jamaica, mentioned above] did not focus on analytical data,
such as chemical composition and potency of cannabis used, making it difficult to
understand the effects or reliability of this administration form. Fortunately, the
introduction of high grade cannabis for medicinal use in The Netherlands (in
2003) has provided a good opportunity to study the composition of cannabis tea.
Under the Dutch regime, patients essentially are able to freely choose their
manner of cannabis consumption. Based primarily on health implications, the
Dutch Health Office advices to consume medicinal cannabis preferably by
vaporizing or in the form of a tea, and not by smoking. Indeed, polls under
medicinal cannabis users in The Netherlands have indicated tea preparation to
be a popular way of consuming cannabis. Also in a more recent survey,
conducted by the International Association for Cannabinoid Medicines (IACM),
cannabis tea was found to be popular; among the 953 participants of the online
survey, about 25% had tried tea as a way to consume medicinal cannabis. The
main advantages cited were the long duration of effects, and the low occurrence
of unwanted side-effects.
Considering these developments, a systematic study on the composition of
cannabis tea would clearly be interesting. As part of my own research, we
performed this study on the preparation and handling of cannabis tea, in
particular on the parameters that can have an effect on the composition of the
tea, such as boiling time, volume of tea prepared, and duration of storage. By
performing a series of experiments, we systematically discovered the effect of
different parameters on the cannabinoid composition of medicinal cannabis tea.
In simple words: what happens when I accidentally use too much cannabis, or
when the phone rings and I boil my tea too long? How long can I store tea, and
will the composition be the same each time I prepare it? For a medicine, such
things obviously may be handy to know.
A major concern with the medicinal use of cannabis is the risk of (accidental)
overdosing of THC, which could lead to psychotropic effects. However, our tea
study showed that moderate changes in the standard preparation protocol for
cannabis tea (discussed below) do not result in dramatic changes in the
composition of the tea. Cannabis tea has a unique composition compared to
other forms of administration, where heating of the material is typically performed
at much higher temperatures (e.g. smoking, vaporizing or baking), resulting in a
virtual complete conversion of acidic into neutral cannabinoids. But when
cannabis tea is prepared, with temperatures not exceeding the boiling
temperature of water, a significant proportion of THCA can be found. The
recently described effects of THCA on the immune system (Verhoeckx, 2006)
may contribute to the effects that certain groups of medical users claim after
consumption of cannabis tea.
Also other acidic cannabinoids, such as the acids of CBG and CBC (i mentioned
them above) could be detected in tea, but not in cannabis smoke or in vaporized
cannabis. Although the biological activities of these acidic cannabinoids have
hardly been explored yet, their presence makes cannabis tea a unique
administration form that should not be considered as simply a vehicle for THC. In
conclusion, cannabis tea is already consumed by a large number of patients on a
daily base, and their medical claims may certainly be compatible with the unique
composition of the tea.
7) How to make cannabis tea
After reading all the above, you may have become interested in using medicinal
cannabis in the form of a tea? Then now is a good time to discuss how to actually
prepare it. Clearly there are many ways to prepare a tea, and this book is full of
examples. I will only focus on the method that is advised by the Dutch medicinal
cannabis program, simply because that is the method I have a lot of experience
with. You are free to change the recipe if you like, but please be aware that the
composition of the tea may significantly change when you do. The main
advantage of sticking to a standard protocol for making tea, is that you will get
the same dose of medicine every day.
For starters, you need your favorite type of cannabis. You can use cannabis buds
that are fresh or dried, as long as they are not so old that the terpenes have
evaporated, or the cannabinoids have degraded. A good strong smell (terpenes)
may be a good indicator for freshness. Grind the material to homogenize it,
otherwise the different cups of tea may have a significantly different composition.
Now bring water to a rolling boil, and add cannabis. For each liter (quart) of
water, 1 gram of cannabis should be used. Bring back the boiling to a simmer,
and cover the pan with a lid to prevent evaporation (and to keep more terpenes
in the tea).
A boiling time of 15 minutes was found to be optimal in lab studies. Boiling for a
shorter period leads to a much less potent product, because the acidic
cannabinoids do not have sufficient time to convert to their more potent
counterparts. On the other hand, boiling longer did not much change the
composition of the tea. It seems that after about 15 minutes the composition of
the tea stabilizes, because the water can not take up any more cannabinoids; a
saturated solution forms, because of the limited solubility of cannabinoids in
After 15 minutes of boiling, strain out the solid plant parts by using a strainer or a
sieve. The left over plant material looks very soggy but does still contain active
ingredients. Although I have personally never tried it, you may be able to find a
purpose for it (perhaps dry it in the oven and use it for baking?). The tea you just
produced may taste a little harsh and ‘green’, depending on the cannabis variety
you used. At this point, you may add some honey, milk, or perhaps flavored tea
like peppermint. Brew your own favorite and see what works for you.
I don’t need to tell you that the fresher the tea, the tastier. But that is a lot of work
when you need multiple cups of tea per day. A liter (1 quart) of tea would supply
you with 3-5 cups of tea and therefore seems to be a proper volume to prepare
each day. Storage of cannabis tea, for one day or longer, is of particular
importance, and will be discussed in the next section of this chapter.
If you wonder how cannabis tea compares to smoking a similar amount of
cannabis, consider this: One daily volume of tea (1 liter) contains 1 gram of
cannabis, and will yield on average 4 doses (cups) of tea, to be consumed
throughout the day. By comparison, the same 1 gram of cannabis could be used
to roll about 2 cannabis cigarettes, each containing half a gram of cannabis. This
would translate to 4 doses per day, when smoking half a cigarette per dosing.
Please remember that the tea preparation may feel less potent, because it has
less THC in it, and therefore a lower potential to make you high. However, the
composition of tea is very different from cannabis smoke (think THCA), and its
medicinal effect may be just what you need.
One final warning would be in place here. When using cannabis orally (by
ingesting it), all the active components present will be absorbed by the intestines,
and will be sent straight to the liver. There, a large part of the cannabinoids are
converted in slightly different compounds (e.g.: 11-hydroxy-THC), which have a
stronger psychoactive potential than the original THC. That is the reason that
edibles and tea may make you feel more high than you are used to. Always be
careful when using cannabis orally, because once you have swallowed it, there is
not much more you can do than sit down and ‘enjoy’ the ride. After each dose, it
is advisable to wait for a few hours before you decide to take another one. Of
course, the advantage of a standard tea preparation is that you will be better able
to predict the effects of your medicine.
8) Solubility of cannabinoids, and implications for storage.
An interesting characteristic of THC, and the many other cannabinoids
mentioned here, is that they are absolutely not soluble in water. When using
boiling water, during the preparation of tea, the cannabinoids will make some
effort to dissolve, but as soon as the tea cools off, you will see the liquid become
turbid. This indicated that the cannabinoids are starting to stick together in large
droplets, which end up as a sticky layer on the inside of your storage container.
Basically, after one day in the fridge, your tea is starting to turn into water again,
and the medicinal effects are quickly lost. This has been visualized in figure 5.
The problem is easily fixed: just add something fatty, like a little milk or coffee
creamer (powder) after preparing the tea, in order to keep the cannabinoids in
solution. Adding butter has been suggested too, but it doesn’t sound particularly
appetizing to me! In this way you can keep tea for up to 5 days, but store it in the
fridge to prevent it from spoiling. Just shake the liquid before pouring yourself a
cup. You can then heat it in a little pan, or by microwave.
When making tea for one day use only, you can also keep the tea in a thermos
so that the tea stays warm and the cannabinoids remain in solution. Always
shake well before you take a cup.
Cannabis tea is a widely used, but poorly understood herbal medicine. It is (yet)
too complicated for modern pharmacology, but also too potent to simply be
considered as alternative medicine. Whether we like it or not, right now we are
stuck in the middle. Cannabis tea, with its low potential for psychoactive effects,
and a unique cannabinoid composition, is an interesting administration form for
herbal cannabis. I hope that the information I presented here will contribute to a
better understanding of cannabis tea, resulting in more appreciation of this
popular form of cannabis administration.
Although it seems clear that the Cannabis plant still has a highly relevant
potential for medicine, it is also clear that the medicinal use of cannabis is not a
panacea. Cannabis, as any other medicine, can have its side effects, especially
when consumed in high amounts. A widely expressed opinion on the unwanted
actions of cannabis and THC has been formulated in a 1999 report of the US
Institute of Medicine on the medical use of cannabis: ”Marijuana is not a
completely benign substance. It is a powerful drug with a variety of effects.
However, except for the harms associated with smoking, the adverse effects of
marijuana use are within the range of effects tolerated for other medication” [Joy,
With these wise words this chapter has come to an end. I hope you will enjoy the
benefits that cannabis, consumed in the form of a tea, has to offer you. I am
certain that we will see the birth of many cannabis-based medicines in the near
future. But for now: Cheers.
Suggested further reading
M Ben Amar. Cannabinoids in medicine: A review of their therapeutic potential. J.
Ethnopharm. 2006, 105, 1-25.
A Hazekamp. An evaluation of medicinal grade cannabis in The Netherlands.
Cannabinoids 2006, 1(1), 1-9.
A Hazekamp, K Bastola, H Rashidi, J Bender, R Verpoorte. Cannabis tea
revisited: A systematic evaluation of the cannabinoid composition of cannabis
tea. J. Ethnopharm. 2007, 113, 85-90.
A Hazekamp and F Grotenhermen. Review on clinical studies with cannabis and
cannabinoids 2005-2009. Cannabinoids 2010, 5(special issue), 1-21.
J Holland. The Pot Book - A Complete Guide to Cannabis: Its Role in Medicine,
Polititcs, Science, and Culture. Park Street Press, Rochester, 2010.
AA Izzo, F Borrelli, R Capasso, V Di Marzo, R Mechoulam. Non-psychotropic
plant cannabinoids: new therapeutic opportunities from an ancient herb. Tr.
Pharmacol. Sci. 2009, 30(10), 515-527.
JE Joy. Marijuana and medicine: assessing the scientific base; Institute of
Medicine, USA: 1999.
R Mechoulam. Plant cannabinoids: a neglected pharmacological treasure trove.
Br. J. Pharmacol. 2005, 146(7), 913-915.
V Rubin, L Comitas L. Ganja in Jamaica, a medical anthropological study of
chronic marihuana use. Mouton, The Hague, 1975.
W Snoeijer. A checklist of some Cannabaceae cultivars. Part 1: Cannabis.
Division of Pharmacognosy, Leiden/Amsterdam Centre for Drug Research, The
KC Verhoeckx, HA Korthout, AP van Meeteren-Kreikamp, KA Ehlert, M Wang, J
van der Greef, RJ Rodenburg, RF Witkamp. Unheated Cannabis sativa extracts
and its major compound THC-acid have potential immuno-modulating properties
not mediated by CB1 and CB2 receptor coupled pathways. Int.
Immunopharmacol. 2006, 6(4), 656-665.
Figure 1: Medicinal cannabis available on prescription in the Netherlands in 5 gram jars.
Figure 2: Microscope photograph and drawing of a cannabis resin gland, with secretory
head cells visible underneath the transparent cannabinoid- and terpenoid-rich resin.
Source: drawing from Hashish!, by R. Clarke. Los Angeles: Red Eye Press, 1998.
Ask permission for reprinting!
Figure 3: chemical structures of the most important cannabinoids found in
Figure 4: decarboxylation of cannabinoids converts acidic cannabinoids to their
neutral counterparts. The conversion of THCA to THC is shown as an example.
THC-acid T HC
heat, light, storage
Figure 5: the effect of storing cannabis tea in the refrigerator without stabilizer. Already
after a single day, the potency of THC and THCA in the tea has decreased dramatically.
(Data is taken from Hazekamp 2007)
Fresh tea After storage in the refrigerator
Relative amount of THC or
THCA present per cup of tea