The Botany of Cannabis sativa L
The Botany of Cannabis sativa L.
Cannabis sativa L is a widely distributed species found in diverse habitats, from sea level to the Himalayan foothills, with its spread likely occurring over the last 10,000 years The extensive history of its cultivation complicates the identification of its original distribution This plant has been used medicinally for centuries in the Middle East and Asia, with records dating back to the 6th century BCE It was introduced to Western Europe in the early 19th century as a treatment for various conditions, including epilepsy, tetanus, rheumatism, migraine, asthma, trigeminal neuralgia, fatigue, and insomnia.
Cannabis is highly regarded for its hallucinogenic and medicinal properties, being utilized for conditions such as pain, glaucoma, nausea, asthma, depression, insomnia, and neuralgia Its derivatives are also beneficial in treating HIV/AIDS and multiple sclerosis Extensive research has been conducted on the pharmacology and therapeutic efficacy of cannabis preparations, particularly focusing on its primary active compound, Δ9-tetrahydrocannabinol (Δ9-THC) Recently, cannabidiol (CBD) has gained significant attention for its potential as an antiepileptic agent, especially in treating intractable pediatric epilepsy Other notable cannabinoids include tetrahydrocannabivarin (THCV), cannabinol (CBN), cannabigerol (CBG), and cannabichromene (CBC).
Cannabis, one of the oldest sources of food and textile fiber, saw the introduction of hemp cultivation for fiber in Western Asia and Egypt around 1517, spreading to Europe between 1000 and 2000 BCE By 500 CE, hemp became widely cultivated in Europe, with its first introduction to South America occurring in Chile in 1545 and to North America in Port Royal, Acadia, in 1606 Today, however, the cultivation of hemp is either prohibited or heavily regulated in the United States.
The Analytical Chemistry of Cannabis DOI: http://dx.doi.org/10.1016/B978-0-12-804646-3.00001-1
Copyright © 2016 Elsevier Inc All rights reserved.
Cannabis sativa L is a highly variable species characterized by its diverse botanical, genetic, and chemical properties The classification of species within the Cannabis genus has been a topic of debate, with some suggesting it is a polytypic genus However, extensive morphological, anatomical, phytochemical, and genetic research typically recognizes it as a single, highly polymorphic species, C sativa L.
Cannabis sativa is the primary species of cannabis, encompassing notable varieties such as Cannabis indica and Cannabis ruderalis, which are now classified as subspecies of C sativa (var indica and var ruderalis) The major cannabinoids found in Cannabis sativa include Δ9-THC (tetrahydrocannabinol), THCV (tetrahydrocannabivarin), CBN (cannabinol), CBG (cannabigerol), CBC (cannabichromene), and CBD (cannabidiol) While Cannabis sativa and indica are extensively cultivated for their economic value, Cannabis ruderalis is more resilient and thrives in harsher climates, such as the northern Himalayas and southern regions of the former Soviet Union, though it is infrequently grown for its psychoactive properties.
The primary morphological distinction between indica and sativa cannabis plants lies in their leaves and overall structure Indica leaves are broad, deep green, and often have a purple hue, while sativa leaves are smaller and thinner Indica plants are typically shorter and bushier, reaching heights of under 6 to 8 feet, and produce thick, dense buds that mature early, usually by early September in the Northern Hemisphere In contrast, sativa plants can grow significantly taller, ranging from 6 to over 20 feet, with long branches that spread wide from the central stalk Sativa buds are longer and less densely populated than indica buds, with maturation times varying based on the specific variety and environmental factors Indica is primarily found in regions like Afghanistan, Pakistan, and India, while sativa varieties, including low-THC types, have different maturation timelines depending on their geographical origins.
Table 1.1 Botanical Nomenclature of Cannabis sativa L.
Cannabis sativa L varieties mature between October and December, requiring intense light for the buds to thicken and swell, unlike indica strains Sativa is typically higher in Δ9-THC and lower in CBD compared to indica This species is globally distributed and includes potent equatorial varieties such as Colombian, Mexican, Nigerian, and South African cannabis Additionally, Cannabis has various local common names, as detailed in Table 1.2.
Cannabis typically displays a dioecious nature, with male and female flowers growing on separate plants, though it can also present a monoecious (hermaphroditic) phenotype The plant flowers when exposed to shorter photoperiods of less than 12 hours, while it continues its vegetative growth during longer photoperiods The determination of sex in cannabis is governed by heteromorphic chromosomes, with males being heterogametic.
In plants, males are typically XY while females are homogametic XX, leading to distinct morphological differences in their flowers Although it can be challenging to differentiate male and female plants during the vegetative stage due to their similarities, molecular techniques enable early identification of their sexes.
Cannabis is primarily wind-pollinated, with female plants being favored for cannabinoid production due to their higher yield of cannabinoids Additionally, once pollinated, female plants produce seeds upon reaching maturity, unlike their seed-free counterparts.
Table 1.2 Common Cannabis Names in Different Languages
Arabic Bhang, hashish qinnib, hasheesh kenneb, qinnib, tợl
Chinese Xian ma, ye ma
French Chanvre, chanvre d’Inde, chanvre indien, chanvrier
German Hanf, haschisch, indischer hanf
Spanish Cỏủamo, grifa, hachớs, mariguana, marijuana
Swedish Porkanchaa plants, known for their higher yield of secondary metabolites, are favored in cannabis cultivation To maintain the desired chemical profile and quality of the final product, it is crucial to prevent cross-pollination when growing multiple cannabis varieties This can be achieved by promptly removing male plants, screening female clones for elevated metabolite content, and employing biotechnological tools for conservation and multiplication, ensuring consistency in pharmaceutical applications.
CHEMICAL CONSTITUENTS AND PHENOTYPES OFC SATIVA L.
CBN was the first cannabinoid isolated from Cannabis sativa, leading to the speculation that the active constituents of cannabis could be THCs Following this, CBD was isolated from Mexican marijuana, and its structure was determined Pioneers Gaoni and Mechoulam successfully isolated and identified the structure of Δ9-THC, marking a significant advancement in cannabis research Since then, the number of cannabinoids and compounds isolated from cannabis has continuously increased, with a total of 545 reported, including 104 phytocannabinoids.
Table 1.3 Constituents of Cannabis sativa L.
No Groups Number of Known Compounds
A total of 61 phytocannabinoids have been isolated and documented, with only nine new compounds characterized between 1981 and 2005 In contrast, 31 new phytocannabinoids were reported from 2006 to 2010 The presence of 13 distinct chemical constituent groups indicates the significant chemical complexity of the cannabis plant.
The qualitative and quantitative characterization of Δ9-THC and CBD, the primary cannabinoids, involves analyzing the Δ9-THC/CBD ratio to classify the plant into distinct chemical phenotypes, known as chemotypes.
In 1971, Fetterman et al classified cannabis into two primary phenotypes: drug type, characterized by a Δ 9-THC/CBD ratio of 0.1 or higher, and fiber type, with a lesser ratio By 1973, Small and Beckstead expanded this classification into three categories: drug type (≥0.1), intermediate (close to 1), and fiber type (≤0.1) Later, in 1987, Fournier et al introduced a rare chemotype distinguished by very low levels of Δ 9-THC and CBD, with cannabigerol (CBG) as the dominant compound.
Biosynthesis and Pharmacology of Phytocannabinoids
Cannabis contains a variety of essential compounds beyond nucleic acids, proteins, lipids, and carbohydrates, including a diverse array of secondary metabolites such as phytocannabinoids, terpenoids, and phenylpropanoids Phytocannabinoids, in particular, are frequently highlighted for their unique properties and effects.
Cannabis contains various chemical constituents, including phytocannabinoids, terpenoids, and flavonoids, which possess a wide range of pharmacological properties These components play a significant role in the effects experienced during cannabis ingestion, combustion, and inhalation, and they also contribute to the efficacy of cannabis extracts, tinctures, and other formulations This overview highlights the importance of these active ingredients in understanding the therapeutic potential of cannabis.
Phytocannabinoids are a diverse group of naturally occurring chemicals found in the Cannabis genus, specifically the Cannabaceae family They are primarily derived from a common precursor known as cannabigerolic acid (CBGA) or its C19 variant, cannabigerovaric acid (CBGVA) These phytocannabinoid precursors are formed through the reaction of geranyl pyrophosphate with olivetolic and divarinic acid, respectively.
Enzymatic conversion of cannabigerolic and cannabidivaric acid produces a wide variety of C21 terpenophenolics, 6 including
(2)-trans-Δ 9 -tetrahydrocannabinol (Δ 9 -THC), cannabigerol (CBG), cannabichromene (CBC), cannabicyclol (CBL), cannabidiol (CBD), cannabinodiol (CBND), and cannabinol (CBN), and their C19
The Analytical Chemistry of Cannabis DOI: http://dx.doi.org/10.1016/B978-0-12-804646-3.00002-3
Copyright © 2016 Elsevier Inc All rights reserved. homologsΔ 9 -tetrahydrocannabivarin (Δ 9 -THCV), cannabivarin (CBV), and cannabidivarin (CBDV) More than 100 phytocannabinoids across
11 chemical classes have been isolated and identified to date 7 In the growing Cannabis sativaplant, most of these cannabinoids are initially formed as carboxylic acids (eg, Δ 9 -THCA, CBDA, CBCA, and
Cannabigerolic acid (CBGA) Cannabigerovarinic acid (CBGVA)
R=propyl - Cannabidivarinic acid (CBDVA) R=pentyl - Cannabidiolic acid (CBDA)
R=propyl - Δ 9 -Tetrahydrocannabivarinic acid (THCVA) R=pentyl - Δ 9 Tetrahydrocannabinolic acid (THCA)
R=propyl - Cannabichromevarinic acid (CBCVA) R=pentyl - Cannabichromenic acid (CBCA)
Phytocannabinoids are synthesized through a biosynthetic process, with Δ9-THCVA being a key precursor that undergoes decarboxylation into its neutral form due to factors such as drying, heating, combustion, or aging Additionally, various isomers of phytocannabinoids can arise from changes in the positioning of the double bond during isomerization.
CBDA - R 1 = pentyl, R 2 = COOH CBD - R 1 = pentyl, R 2 = H CBDVA - R 1 = propyl, R 2 = COOH CBDV - R 1 = propyl, R 2 = H
CBNA - R 1 = pentyl, R 2 = COOH CBN - R 1 = pentyl, R 2 and R 3 = H CBNV - R 1 = propyl, R 2 and R 3 = H
CBGA - R 1 = pentyl, R 2 = COOH CBG - R 1 = pentyl, R 2 = H CBGVA - R 1 = propyl, R 2 = COOH CBGV - R 1 = propyl, R 2 = H
CBLA - R 1 = pentyl, R 2 or R 3 = COOH CBL - R 1 = pentyl, R 2 and R 3 = H CBLV - R 1 = propyl, R 2 and R 3 = H Δ 9 -Tetrahydrocannabinol (THC) Δ 9 -Tetrahydrocannabivarin (THCV)
CBEA-C5 - R 1 = pentyl, R 2 or R 3 = COOH CBE-C5 - R 1 = pentyl, R 2 = H CBEA-C3 - R 1 = propyl, R 3 = COOH CBE-C3 - R 1 = propyl, R 2 = H
Figure 2.2 illustrates the primary phytocannabinoid constituents found in cannabis Notably, CBN is not produced biosynthetically; rather, it is an oxidative degradation product of Δ 9 -THC.
The regulation of cannabinoid content in plant phenotypes, or chemotypes, is believed to be genetically controlled by the expression of synthetic enzymes across four independent loci This genetic variation leads to distinct chemical compositions in progenies, particularly affecting the ratios of phytocannabinoids like Δ9-THC and CBD The total phytocannabinoid content is influenced by polygenic mechanisms and environmental factors, often resulting in a Gaussian distribution Additionally, as the plant matures, its cannabinoid profile evolves, with wild-type chemotypes exhibiting significant differences in cannabinoid predominance and total content, sometimes exceeding 2530% in dry inflorescences Selective breeding and spontaneous mutations have generated unique chemotypes, including those with CBGA, CBCA, or Δ9-THCVA predominance, as well as cannabinoid-free variants This selective breeding has led to the development of hundreds of strains, each preferred for their specific pharmacological effects Looking ahead, future breeding may yield novel terpeno-phenolic compounds and chemotypes with enhanced ratios of lesser-known cannabinoids.
The variation in phytocannabinoid content among different cannabis chemotypes significantly impacts medicinal cannabis formulations and dosing This diversity is evident in the wide range of cannabis varieties being cultivated and marketed for both medicinal and recreational use Additionally, the nonphytocannabinoid components of cannabis, particularly terpenoids and flavonoids, are gaining increasing attention in pharmacological research.
MONOTERPENOID, SESQUITERPENOID, AND DITERPENOID CONSTITUENTS OF CANNABIS
Geranyl pyrophosphate serves as a crucial precursor in the synthesis of terpenoids, facilitating the production of limonene and other monoterpenoids within secretory cell plastids Additionally, it can combine with isopentenyl pyrophosphate in the cytoplasm to generate farnesyl pyrophosphate, an essential intermediate for the biosynthesis of sesquiterpenoids and triterpenoids The addition of another isopentenyl group to farnesyl pyrophosphate results in geranylgeranyl pyrophosphate, which is vital for the formation of diterpenoids Notably, some of the prominent volatile monoterpenes found in cannabis include β-myrcene, (E)-β-ocimene, terpinolene, limonene, and β-pinene, alongside β-caryophyllene and α-caryophyllene.
(humulene), longifolene, α-zingiberene, and β-cedrene are among the major sesquiterpenes found in prototypical cannabis samples 16
Phenylpropanoids are notable for their wide-ranging pharmacological and industrial applications, with their biosynthesis initiated from phenylalanine via the shikimate pathway This process involves the conversion of phenylalanine into cinnamic acid by phenylalanine ammonia lyase, followed by the hydroxylation of cinnamic acid into p-coumaric acid through the action of cinnamate-4-hydroxylase The resulting p-coumaric acid is then transformed into p-coumaroyl CoA by a 4-coumarate:CoA ligase, serving as a high-energy intermediate essential for synthesizing cell wall components like lignins, pigments such as flavonoids and anthocyanins, and compounds that provide UV protection and pest resistance Chalcone synthase (CHS), a crucial enzyme in the flavonoid biosynthesis pathway, is part of the polyketide synthase superfamily and plays a significant role in the development of glandular trichomes in cannabis The activities of polyketide synthases, which facilitate the production of cannabinoids, stilbenoids, and flavonoids, are stimulated by various factors, including UV light, pathogens, hormones, and physical damage Some naturally occurring flavonoids include orientin, vitesin, luteolin-7-O-β-D-glucuronide, and apigenin-7-O-β-D-glucuronide.
THERAPEUTIC INDICATIONS FOR MEDICINAL CANNABIS AND CANNABIS-DERIVED DOSAGE FORMULATIONS
Cannabis and its derivatives, such as hashish, have a long-standing history of medicinal use, yet their intoxicating effects and potential for abuse have hindered extensive clinical research The most recognized therapeutic applications of herbal cannabis include alleviating nausea and vomiting caused by chemotherapy, addressing anorexia and cachexia in HIV/AIDS patients, managing chronic and neuropathic pain, and reducing spasticity in multiple sclerosis and spinal cord injuries Recent reviews of randomized clinical trials support these uses and also suggest benefits for sleep disorders and Tourette’s syndrome While glaucoma was once a common medical indication for cannabis in the late twentieth century, its relevance has significantly decreased over time.
Cinnamic acid Cinnamate-4-hydroxylase HO
OH H H p -Coumaric acid 4-Coumarate: CoA ligase enzyme HO
Stilbenes, dihydrostilbenes, prenylated stilbenes, etc
FLAVONOID BIOSYNTHESIS Flavanones, flavanonols, flavans, anthoxanthins, anthocyanidins, isoflavanoids
Cannabis has a historical use in managing epileptic seizures, with recent reviews highlighting its potential While the Institute of Medicine does not fully endorse cannabis or cannabinoid-derived drugs for seizure control, CBD has garnered significant attention and anecdotal evidence as a treatment for Dravet Syndrome and other specific seizure disorders Additionally, research is exploring its efficacy for other conditions, including irritable bowel syndrome and post-traumatic stress disorder.
PHARMACOLOGICAL EFFECTS OF CANNABIS CONSTITUENTS
The therapeutic and organoleptic effects of cannabis are influenced by various chemical constituents, which differ in concentration, chemical properties, pharmacological actions, and physicochemical parameters While the primary acidic forms of phytocannabinoids, such as Δ9-THCA, CBNA, and CBGA, were traditionally thought to lack psychoactivity, recent studies have revealed that Δ9-THCA exhibits significant antinausea and antiemetic effects, surpassing the potency of Δ9-THC Furthermore, Δ9-THCA binds to CB1 and CB2 receptors with greater affinity than Δ9-THC and demonstrates immunomodulatory actions independent of these receptors Consequently, additional research on the pharmacological activity and mechanisms of Δ9-THCA is warranted.
Δ9-THC is recognized as the main psychoactive phytocannabinoid due to its quick conversion from Δ9-THCA through decarboxylation when plant material is burned, leading to high levels in smoke during inhalation This rapid formation contributes to its effectiveness at cannabinoid receptors, particularly the CB1 receptor, where studies indicate that Δ9-THC binds with high affinity, demonstrating its potency at physiologically relevant concentrations.
B50 nM), while CBN has an approximately 10-fold lower affinity,and CBD and CBG have K i values estimated to be greater than
Δ9-THC exhibits a high binding affinity to both CB1 and CB2 receptors, correlating with its ability to inhibit adenylate cyclase and produce analgesic and psychoactive effects While it acts as a partial agonist in GTP-γ-S assays, its efficacy is lower compared to synthetic cannabinoids like CP-55940 and WIN55212-2 The response of Δ9-THC is significantly influenced by tissue-specific expression levels, constitutive signaling, and endogenous cannabinoid release Beyond its psychoactive properties, Δ9-THC also triggers a range of cannabinoid receptor-mediated pharmacological effects in both laboratory animals and humans.
Various phytocannabinoids interact with cannabinoid receptors, notably Δ 8 -THC and Δ 9 -THCV, which act as agonists at CB1 and CB2 receptors with affinities similar to Δ 9 -THC Δ 9 -THCV can induce mild psychoactive effects in humans and catalepsy and analgesia in animals, while also exhibiting antagonist properties in certain tissues Additionally, CBN binds to CB1 and CB2 receptors but with lower affinity than Δ 9 -THC, producing only mild intoxication at high doses Other than these compounds, few phytocannabinoids have demonstrated significant receptor activation In contrast, CBD and CBDA are non-psychoactive and do not bind effectively to CB1 or CB2, although CBD has been shown to act as a potent antagonist in cells expressing these receptors.