The previous few years have witnessed considerable focus on cannabidiol (CBD), a primary non-psychotropic component of Cannabis. The Part I of this review presents a concise survey of the chemistry of CBD; in Part II, to be published later, the anti-convulsive, anti-psychotic, anti-anxiety, anti-nausea, and anti-rheumatoid/arthritic properties of CBD will be discussed. CBD does not attach to the known cannabinoid receptors and its mechanism of action is still unknown. In Part II, evidence would be presented that will be conceivable in part at least that the effects of CBD arise from its inhibition of anandamide uptake and hydrolysis and to its anti-oxidative activity.
After the isolation and exposition of the structure of the primary active component of the Cannabis plant, D9-tetrahydrocannabinol (THC) a large volume of published articles have explained its chemistry, pharmacology, biochemistry and clinical effects. At the same time, sufficient anecdotal evidence has emerged that the effects of marijuana are not solely due to THC (Grinspoon and Bakalar, 1997). One constituent, cannabidiol (CBD) was found to produce a wide range of pharmacological effects, some of which may alter the metabolism and effects of THC.
CBD Chemistry and Its Pharmacological and Clinical Effects
Based on chemical degradation and correlation with cannabinol, a common structure was proposed. Though, quite strangely for almost 25 years, no future work was reported. In 1963 CBD was isolated from Lebanese hashish and set up its structure and relative stereochemistry, largely on the basis of NMR measurements. After a few years, its absolute stereochemistry was established by conversion of CBD into menthane carboxylic acid of well established definite stereochemistry. These initial results were significant for the later explanation of the structure and stereochemistry of D9-THC, the psychoactive ingredient of Cannabis.
Two independent types of CBD molecule were observed, which were different in the structure of the pentyl side chain. The aromatic ring and the terpene ring are nearly perpendicular to one another. The two conformers are connected by hydrogen bonding of the hydroxyl moieties. The chemical nomenclature of CBD differs from THC. While THC has a pyran ring, which decides its numbering, CBD has no heterocyclic ring and its numbering arises from that of the terpene ring. This somewhat unpleasant technicality results in the same carbon atom being numbered separately in CBD and THC.
CBD has emerged as a new promising medication due to its wide spectrum of pharmacological effects. Findings till the present has revealed that CBD can display the following pharmacological activities which includes:
- Antipsychotic effects in schizophrenia primarily through the facilitation of endocannabinoid signaling and CB1 receptor antagonism
- CBD administration may show acute anxiolytic effects in patients with a generalized social anxiety disorder by altering cerebral blood flow in particular sites of the brain and serotonin 1A receptor agonism
- CBD may minimize withdrawal symptoms and cannabis/tobacco dependence through regulation of endocannabinoid, serotoninergic and glutamatergic systems. Present evidence indicates that CBD has the potential to lower psychotic, anxiety and withdrawal signs by means of various hypothesised pharmacological properties.
Photochemical Reactions Of CBD
This study also noted the irradiation of CBD in methanol with a 450W lamp in a Corex vessel produced a mixture from which chiefly isomeric 1-methoxy dihydro CBD’s were obtained. However, irradiation in cyclo-hexane resulted in the creation of some THC, in addition to iso-THC, decreased CBD and the addition product cyclohexane to CBD producing cyclohexyl CBD. These reactions hint that CBD is photoreactive and should be safeguarded from light during storage.
Besides, this review also reported on the synthesis of CBD, and metabolism of CBD. The metabolism of CBD is well recognized. The chemistry of CBD has been properly explored for the past 35 years. Considering the various therapeutic effects resulting from CBD it seems likely that new synthetic approaches will emerge in the future that would lead to novel types of derivatives.