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REVIEW
Cannabidiol – Recent Advances
by Raphael Mechoulam*a), Maximilian Petersa), Eric Murillo-Rodriguezb) , and Lum"r O. Hanusˇ a)
a) Department of Medicinal Chemistry and Natural Products, Hebrew University Medical Faculty,
Jerusalem 91120, Israel (phone : þ972-2-6758643 ; e-mail : mechou@cc.huji.ac.il)
b) Departamiento de Neurociencias, Instituto de Fisiologia Celular, Ciudad Universitaria,
Circuito Interior, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico
The aim of this review is to present some of the recent publications on cannabidiol (CBD; 2) , a major
non-psychoactive constituent of Cannabis, and to give a general overview. Special emphasis is laid on
biochemical and pharmacological advances, and on novel mechanisms recently put forward, to shed light
on some of the pharmacological effects that can possibly be rationalized through these mechanisms. The
plethora of positive pharmacological effects observed with CBD make this compound a highly attractive
therapeutic entity.
Contents
1. Introduction
2. Mechanisms of Cannabidiol Action
2.1. Cannabidiol: an Antagonist of CB1- and CB2-Receptor Agonists
2.2. Cannabidiol: Enhancer of Adenosine Signaling
2.3. Cannabidiol: Action on the 5-HT1a Receptor
2.4. Cannabidiol: a Potent Anti-Oxidant
3. Synthetic Approaches to Cannabidiol and Cannabidiol-Like Molecules
4. Cannabidiol: Selected Biological Effects
4.1. Cannabidiol: an Allosteric Modulator of Opioid Receptors
4.2. Cannabidiol, Cytokines, and Related Endogenous Constituents
4.3. Cannabidiol and Sleep
4.4. Cannabidiol and C-Fos
5. Cannabidiol: Selected Therapeutic Aspects
5.1. Neuroprotection
5.2. Cerebral Ischemia
5.3. Type-1 Diabetes
5.4. Anti-Emetic and Antinausea Effects
5.5. Anxiety
5.6. Rheumatoid Arthritis
5.7. Cancer
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007)1678
2007 Verlag Helvetica Chimica Acta AG, Zrich
1. Introduction. – Over the last 40 years, cannabinoid chemistry and pharmacology
have been the object of thousands of publications. For obvious reasons, most attention
has been paid to D9-tetrahydrocannabinol (THC; 1), the psychoactive constituent of
Cannabis. As cannabidiol (CBD; 2)
1
), a non-psychotropic plant constituent, is
generally found in relatively high concentrations in Cannabis, several groups have
also investigated the pharmacological activities of this component, although not to the
extent that THC was investigated. Over the last decade, however, interest in CBD has
increased considerably.
Several groups have summarized the knowledge gathered on CBD up to the last
few years [1 – 5] . We have published two concise reviews, the first dealing with the
chemistry of CBD [6] , and the second related to its pharmacology and biological effects
[7]. The aim of the present review is to collect some of the recent publications, to give a
general overview of the field, with emphasis on biochemical/pharmacological advances
as well as on novel mechanisms recently revealed, and to try to shed light on some of
the pharmacological effects that can possibly be rationalized through these mecha-
nisms.
2. Mechanisms of Cannabidiol Action. – CBD (2) does not cause marijuana-like
effects. However it has been shown to produce a plethora of pharmacological effects,
many of them associated with both central and peripheral actions (see below). Until
recently, very little was known about the biochemical/physiological basis of these
activities. Over the last two years, several groups have reported some unexpected
observations.
2.1. Cannabidiol: an Antagonist of CB1- and CB2-Receptor Agonists. CBD (2) has a
very low affinity for both known cannabinoid receptors, CB1and CB2. However,
Pertwees group in Aberdeen showed that CBD antagonizes the CB1agonists and
noradrenaline in mouse vas deferens, a tissue in which prejunctional CB1receptors
mediate inhibition of electrically evoked contractions by suppressing noradrenaline
and ATP release [1] . CBD attenuated the ability of the CB1agonists WIN55212 and
CP55940 to affect contractions at doses considerably lower than those of CBD needed
to activate cannabinoid receptors. Their conclusion was that CBD antagonizes the
above two cannabinoid agonists by acting at prejunctional sites that are unlikely to be
CB1or CB2cannabinoid receptors. In a more recent publication, the Aberdeen group
reported that these actions are actually cannabinoid-receptor-mediated [8] . They
found that CBD is a high-potency antagonist of cannabinoid-receptor agonists in
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007) 1679
1) Systematic name: 2-[(1R,6R)-3-methyl-6-(1-methylethenyl)cyclohex-2-en-1-yl]-5-pentylbenzene-
1,3-diol.
mouse brain and in membranes from cells transfected with human CB2. CBD was also
found to display inverse agonism at the human CB2receptor. These unexpected
observations may rationalize many of the effects recorded with CBD, such as its anti-
inflammatory properties.
2.2. Cannabidiol: Enhancer of Adenosine Signaling. On examining the effects of
CBD (2) on microglial proliferation, the Hillard group in Wisconsin found that CBD
potently inhibits [3H]thymidine incorporation into a murine microglial cell line, with no
effect on the cell cycle [9]. Treatment with CBD decreased [3H]thymidine uptake into
microglia, with an IC50 value matching inhibition of [3H]thymidine incorporation into
DNA. CBD decreased uptake of [3H]adenosine to a similar extent as [3H]thymidine in
both murine microglia and RAW264.7 macrophages. Binding studies confirmed that
CBD binds to the equilibrative nucleoside-transporter-1, with a Kivalue below 250 nm.
It seems reasonable to assume that CBD is immunosuppressive, because it enhances
endogenous adenosine signaling. In vivo treatment with a low dose of CBD is known to
decrease TNF-aproduction in lipopolysaccharide (LPS )-treated mice [10]; this effect
is reversed with an A2A adenosine-receptor antagonist, and abolished in A2A receptor
knockout mice. Thus, it was demonstrated that CBD has the ability to enhance
adenosine signaling through inhibition of uptake and provide a further non-
cannabinoid-receptor mechanism by which CBD can decrease inflammation.
2.3. Cannabidiol: Action on the 5-HT1a Receptor. CBD (2) displaces the agonist
[3H]-8-hydroxy-2-di-n-propylamino-tetralin ([3H]-8-OH-DPAT) from the cloned
human 5-HT1a receptor in a concentration-dependent manner [11]. In contrast,
THC (1) does not displace this agonist from the receptor in equivalent micromolar
concentrations. CBD is a modest-affinity agonist at the human 5-HT1a receptor;
however, CBD increases [35S]GTPgS binding in this G-protein-coupled receptor
(GPCR) system, as does the agonist serotonin. In addition, in this GPCR system, which
is negatively coupled to cAMP production, both CBD and 5-hydroxytryptamine
decrease the cAMP concentration at similar apparent levels of receptor occupancy [11].
As described below, CBD significantly reduces the infarct volume induced by
middle-cerebral-artery (MCA ) occlusion in a bell-shaped curve. This neuroprotective
effect of CBD was inhibited by WAY100135, a serotonin (5-HT1A)-receptor
antagonist, but not by capsazepine, a vanilloid-receptor antagonist. The cerebral blood
flow, increased by CBD, was partially reversed by WAY100135. These results suggest
that the neuroprotective effect of CBD may be related to the increase in cerebral blood
flow through the serotonergic 5-HT1A receptor [12] .
2.4. Cannabidiol: a Potent Anti-Oxidant. Phenols, including resorcinols, are well-
known anti-oxidants. The plant cannabinoids, being monophenols, monophenolic
ethers (like THC (1)) , or resorcinols (as CBD (2)) are likewise potent anti-oxidants.
Eshar et al. [13] found that HU-211, a (þ)-THC-type cannabinoid, is a neuroprotective
agent that combines NMDA-receptor antagonistic activity and free-radical-scavenging
abilities in a single molecule. Following the same type of reasoning, Hampson et al. [14]
investigated the anti-oxidative properties of CBD, and recorded that it prevents
hydroperoxide (H2O2)-induced oxidative damage equally well, or better, than
ascorbate (vitamin C) or tocopherol (vitamin E). Their data suggest that CBD may
be a potentially useful therapeutic agent for the treatment of oxidative neurological
disorders such as cerebral ischemia.
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007)1680
In a more recent study, Hamelink et al. [15] found that CBD, when administered
concurrently with binge ethanol exposure in rats, protected against hippocampal-
entorhinal-cortical neurodegeneration. They showed that this protection was not due to
NMDA-receptor antagonism, as other NMDA antagonists that are not anti-oxidants
did not prevent cell death, and attributed the CBD action to its anti-oxidative effects.
3. Synthetic Approaches to Cannabidiol and Cannabidiol-Like Molecules. –
Recently, Kobayashi et al. [16] reported a new pathway for the synthesis of CBD (2)
and its analogues. The key reaction was nickel (Ni)-catalyzed allylation of cyclohex-2-
ene-1,4-diol monoacetate with a new reagent system, consisting of [Zn(alkenyl)Cl] ,
N,N,N’,N’-tetramethylethylene-1,2-diamine (TMEDA) , and catalytic amounts of
[NiCl2(tpp)2], which gave an SN2-type product in good yield, and with 94%
regioselectivity. While of considerable interest as a synthetic exercise, the new pathway
is less facile than the previous one-step synthesis reported by Baek et al. [17].
Syntheses of both THC (1) and CBD (2) are by routes that lead either to racemates
or require chiral precursors to obtain the natural products in their enantiomeric forms.
Trost and Dogra [18] have shown that THC can be synthesized in enantiomerically pure
form through molybdenum (Mo)-catalyzed asymmetric alkylation of a sterically
congested doubly ortho-substituted entity. An important intermediate in their route
was a hydroxylated dihydrocannabidiol, which presumably can be converted into CBD
proper with synthetic ease. From a practical viewpoint, however, the new pathway is
also less facile than the previous one-step synthesis of Baek et al. [17].
Agonists of the CB1cannabinoid receptor inhibit electrically evoked contractions of
the vas deferens by mediating inhibition of the evoked release of the contractile
neurotransmitters. CBD antagonizes this effect. Thomas et al. [19] reported the
synthesis of the new CBD derivative 6’’-azidohex-2’’-yne-cannabidiol’(O-2654; 3)
2
),
and compared it to CBD in antagonizing the effect of a CB1agonist on electrically
evoked contractions of the vas deferens. Compound 3was found to be as potent as CBD
(2). However, it produced this antagonism with a potency that matched its affinity to
the CB1receptor, suggesting that, unlike CBD, it acts as a competitive antagonist.
Moreover, since it did not enhance the amplitude of electrically evoked contractions, it
is presumably also a neutral CB1antagonist.
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007) 1681
2) Systematic name: 5-(6-azidohex-2-yn-1-yl)-2-[(1R,6R)-3-methyl-6-(1-methylethenyl)cyclohex-2-en-
1-yl]benzene-1,3-diol.
Air oxidization of CBD in the presence of base leads to the cannabinoid 1,4-
quinone HU-331 (4)
3
) [20] . This compound displayed antiproliferative activity in
several human cancer cell lines, both in vitro and in vivo. Later, Kogan et al. [21]
investigated its mode of action and presented evidence of a unique mechanism. HU-331
does not cause cancer-cell-cycle arrest, cell apoptosis, or caspase activation. Death of
human cancer cells caused by HU-331 is not mediated by reactive oxygen species
(ROS) or reactive oxygen intermediates (ROI) , as exposure to 4fails to elicit the
generation of ROS. However, HU-331 specifically inhibits DNA topoisomerase II,
even at nanomolar concentrations, but has only a slight, non-significant effect on the
action of DNA topoisomerase I. The cannabinoid quinone HU-331 is a highly specific
inhibitor of topoisomerase II, compared with most known anticancer quinones. Many
of the quinonoid anticancer drugs cause heart damage. HU-331, in contrast, has no
effect on the heart (unpublished results) and may, thus, represent a new potent
anticancer drug.
We have described the syntheses of the major CBD metabolites ()-7-hydroxy-
cannabidiol (5a) and the corresponding carboxylic acid 6a, their dimethylheptyl
(DMH ) homologues 5b and 6b, respectively, as well as the corresponding enantiomeric
compounds in the (þ)-CBD series [22] [23 ]. The starting materials were the respective
CBD enantiomers and their DMH homologues. The binding of these compounds to the
CB1and CB2cannabinoid receptors were compared [24] . Surprisingly, contrary to the
compounds in the ()-CBD series, which do not bind to the receptors, most of the
derivatives in the (þ)-CBD series do bind to the CB1receptor in the low-nanomolar
range; some of these compounds also bind weakly to the CB2receptor. Natural ()-
CBD and synthetic (þ)-CBD, but not the other derivatives, also stimulate the type-1
vanilloid receptor. The (þ)-CBD analogues that bind to the cannabinoid receptors
exert peripheral pharmacological action only [25] .
CBD (2) and its DMH analogue 7were hydrogenated to afford the respective
partly or fully hydrogenated epimeric compounds 8and 9, respectively. The new
derivatives were evaluated for their ability to modulate the production of ROI, nitric
oxide (NO ) , and tumor necrosis factor (TNF-a) by murine macrophages, as well as for
their binding to the CB1cannabinoid receptor. Surprisingly, we found that some of
these derivatives exhibit good binding to CB1. In addition, hydrogenated 2and 7exhibit
bioactivities different from their parent compounds [26] .
Mannila et al. [27] have used a precipitation/complexation method to prepare a
complex of CBD (2) with b-cyclodextrin (b-CD). The effect of b-CD complexation on
the sublingual absorption of CBD was studied in rabbits. The dissolution rate of the
solid CBD – b-CD complex in vitro was significantly higher than that of free CBD ( p<
0.05) . These results demonstrate that the sublingual administration of solid CBD – b-
CD enhances the absorption of CBD in rabbits, when compared to oral administration
of CBD in EtOH solution. Thus, the solid CBD – b-CD complex may provide an
alternative formulation for sublingual administration of CBD.
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007)1682
3) Systematic name: 3-hydroxy-2-[(1R,6R)-3-methyl-6-(1-methylethenyl)cyclohex-2-en-1-yl]-5-pentyl-
cyclohexa-2,5-diene-1,4-dione.
4. Cannabidiol: Selected Biological Effects. – 4.1. Cannabidiol: an Allosteric
Modulator of Opioid Receptors. In view of the known non-competitive interaction
between cannabinoid and opioid receptors, Kathmann et al. [28] examined by means of
kinetics studies whether CBD (2) is an allosteric modulator at m-opioid receptors,
which are particularly sensitive for the measurement of allosteric interactions at G-
protein-coupled receptors. In addition, they also studied whether such a mechanism
also extends to the d-opioid receptor. For comparison, THC (1) and rimonabant (a CB1
cannabinoid-receptor antagonist) were also studied. In m-opioid-receptor-binding
studies on rat cerebral cortex membrane homogenates, the agonist [3H]DAMGO
bound to a homogeneous class of binding sites, with a KDvalue of 0.680.02 nm.The
dissociation of [3H]DAMGO induced by naloxone (10 mm; half-life t1/2 ¼71 min) was
accelerated by both CBD and THC (100 mmeach) by a factor of 12 and 2, respectively.
The [3H]DAMGO dissociation was not affected by rimonabant. In d-opioid-receptor-
binding studies on rat cerebral cortex membrane homogenates, the antagonist
[3H]naltrindole bound to a homogeneous class of binding sites, with a KDvalue of
0.240.02 nm. The dissociation of [3H]naltrindole, induced by naltrindole, was
accelerated by CBD and THC (at 100 mm, each) by a factor of 2 each. [3H]Naltrindole
dissociation was not affected by rimonabant. This shows that CBD is an allosteric
modulator at both m- and d-opioid receptors. This property is shared by THC, but not
by rimonabant. The high levels of cannabinoids needed may, however, indicate that the
actions are not physiologically relevant.
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007) 1683
4.2. Cannabidiol, Cytokines, and Related Endogenous Constituents. Lymph-node
cells (LNC ) from mice treated with CBD (2) showed a diminished IFN-grelease. In
separate in vitro experiments, it was found that CBD suppressed the collagen-type-II-
specific proliferation of LNCs from arthritic mice in a dose-dependent manner [10].
Synovial cells from mice that had been treated with an optimal dose of CBD (5 mg/
kg i.p., daily, for 10 d) released significantly less TNF-a, when cultured in vitro, than
synovial cells from control animals. This finding suggests that the therapeutic action of
CBD in arthritis includes the suppression of TNF-a, a pro-inflammatory cytokine
known to be a major mediator of this disease. This was corroborated by the finding that
CBD, when injected intraperitoneal (i.p.) or subcutaneous (s.c.) at a concentration of
10 mg/kg, blocked lipopolysaccharide (LPS)-induced serum TNF-ain mice. However,
there was no suppression of TNF-arelease by arthritic synovial cells when CBD was
added in vitro, nor could the authors demonstrate that CBD suppressed TNF-arelease
by mouse-bone-marrow-derived macrophages or RAW cells. This discrepancy between
in vivo and in vitro results suggests that the TNF-asuppression, which is observed in
vivo after administration of CBD, might be mediated by an active metabolite of CBD.
Another possibility is that the decreased TNF-aexpression in vivo is an indirect
consequence of a suppressed T-helper-1 response. Whatever the mechanism of action,
CBD exerts a potent immunosuppressive effect in vivo. Thus, the anti-arthritic potency
of CBD seems to be the result of a combination of immunosuppression, especially of a
T-helper-1 response, and an anti-inflammatory action by way of reducing TNF-ain the
synovium, a combination that has proven successful in the past, when anti-IL-12 and
anti-TNF-aentities were combined to treat collagen-induced arthritis. Apart from
these major effects, the authors also demonstrated other in vitro anti-inflammatory
actions of CBD that may contribute to its anti-arthritic potency, such as inhibition of
the release of ROS by zymosan-stimulated neutrophils and blockade of NO production
by peritoneal macrophages.
Sacerdote et al. [29] examined the in vivo and in vitro effect of CBD on the
production of interleukins IL-12 and IL-10 by murine macrophages. CBD, when added
in vitro to peritoneal macrophages, significantly increased IL-12 and decreased IL-10
production, respectively. Surprisingly, CB1- and CB2-receptor antagonists prevented
this modulation. Macrophages from animals treated with CBD at a dose of 30 mg/kg,
either orally or i.p., also produced higher levels of IL-12 and lower levels of IL-10, in
comparison to controls, but the cannabinoid-receptor antagonists did not prevent these
effects. These different effects by cannabinoid antagonists are difficult to rationalize.
Cannabinoids exhibit immunosuppressive actions that include inhibition of IL-2
production in response to a variety of T-cell-activation stimuli. Traditionally, the effects
of these compounds have been attributed to the cannabinoid receptors CB1and CB2,
both of which are expressed in mouse splenocytes. Therefore, the Kaminski group
investigated whether CB1and CB2antagonists affect the role of cannabinoid receptors
in the cannabinoid-induced inhibition of IL-2 production stimulated by phorbol ester/
calcium ionophore (PMA/Io) in mouse splenocytes. PMA/Io-stimulated IL-2 pro-
duction was, indeed, inhibited by CBD, which, however, was not attenuated by the
presence of the cannabinoid antagonists [30] .
The above publications support earlier, rather scarce reports on in vitro effects of
CBD on immune cells, including the modulation of TNF-a, IL-1, and IFN-gby human
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007)1684
peripheral-blood mononuclear cells [ 31] [32 ] and the suppression of chemokine
production by a human B-cell line [33].
4.3. Cannabidiol and Sleep. It is well-established that THC (1) increases sleep [34].
However contradictory reports have been published regarding the action of CBD (2).
An early publication [35] reported biphasic effects in rats : at 20 mg/kg, a decrease in
slow-wave sleep (SWS ) was observed ; but at 40 mg/kg, the SWS time was increased,
while wakefulness was decreased. Tolerance developed rapidly. Human volunteers,
receiving large doses of CBD (160 mg) , spent significantly more time asleep than those
receiving placebo [36] . In a recent clinical double-blind trial, 15 mg CBD administered
with an oromucosal spray appears to have alerting properties as it increased awake
activity during sleep and counteracted the residual sedative activity of 15 mg THC[37].
Murillo-Rodriguez et al. [ 38] reported that intracerebroventricular (icv) administration
of CBD (10 mg/5ml) at the beginning of a lights-on period increased wakefulness and
decreased rapid-eye-movement (REM ) sleep. Enhancement of c-Fos expression was
apparent in waking-related areas in the brain (hypothalamus and dorsal raphe
nucleus) . Extracellular levels of dopamine, serotonin, and noradrenaline were
increased within the nucleus accumbens, whereas the extracellular levels of 3,4-
dihydroxy-l-phenylalanine (l-DOPA) and 5-hydroxy-indole-acetic acid (5-HIAA )
were diminished. None of these effects were found during the lights-off period.
Surprisingly, the endocannabinoid anandamide, which is known to induce sleep, did
not block the effect of CBD. The mechanism of CBD induction of wakefulness is
unknown. It could include changes in dopamine (DA) levels, as the nigrostriatal
dopaminergic system has been pointed to be an important element in the manifes-
tations of cannabinoid-induced behavioral alterations. Indeed, extracellular levels of
DA are enhanced upon THC administration [39] [40]. Apparently, marijuana
constituents, thus, modulate sleep in opposite directions.
4.4. Cannabidiol and C-Fos. Evaluation of c-Fos protein formation by CBD (2)in
the dorsal striatum and nucleus accumbens of male Wistar rats was investigated to
establish neuronal activation. After systemic administration of CBD (120 mg/kg),
haloperidol (1 mg/kg), or clozapine (20 mg/kg), only haloperidol was able to increase
the number of Fos immunoreactive neurons (FIr) in the dorsal striatum. In contrast,
both haloperidol and CBD significantly increased FIr in the nucleus accumbens.
Clozapine produced a barely significant increase in FIr. These results show that CBD is
able to induce FIr in a limbic, but not in a motor-related, area [41].
5. Cannabidiol: Selected Therapeutic Aspects. – 5.1. Neuroprotection. Cannabi-
noids have been reported to provide neuroprotection in acute and chronic neuro-
degeneration [7]. Lastres-Becker et al. [42] examined whether they are also effective
against the toxicity caused by 6-hydroxydopamine, both in vivo and in vitro, which may
be relevant to Parkinsons disease (PD). First, they evaluated whether the admin-
istration of cannabinoids in vivo reduces the neurodegeneration produced by a
unilateral injection of 6-hydroxydopamine into the medial forebrain bundle. As
expected, two weeks after application of this toxin, a significant depletion of dopamine
contents and a reduction of tyrosine hydroxylase activity in the lesioned striatum were
noted, accompanied by a reduction in the level of tyrosine-hydroxylase-mRNA in the
substantia nigra. None of these events occurred in the contralateral structures. Daily
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007) 1685
administration of THC (1) over these two weeks significantly lowered the magnitude of
these reductions, whereas it failed to affect dopaminergic parameters in the
contralateral structures. This effect appeared to be irreversible, since interruption of
the daily administration of the cannabinoid after the two-week period did not lead to
re-initiation of 6-hydroxydopamine-induced neurodegeneration. The same neuro-
protective effect was also produced by CBD (2), which suggested that the anti-oxidant
properties of both compounds, which are cannabinoid-receptor-independent, might be
involved in these in vivo effects, although an alternative rationalization might be that
the neuroprotection exerted by both compounds is due to their anti-inflammatory
potential.
The same group [43] further explored this issue, with more selectivity for different
elements of the cannabinoid-signaling system, using rats with unilateral lesions of
nigrostriatal dopaminergic neurons caused by local application of 6-hydroxydopamine.
Numerous cannabinoids were investigated. The authors also examined the timing for
the effect of CBD to provide neuroprotection in this rat model of PD. They found that
CBD, as expected, was able to recover 6-hydroxydopamine-induced DA depletion,
when administered immediately after the lesion, but failed to do so when the treatment
started one week later. In addition, the effect of CBD caused an upregulation of mRNA
levels of Cu/Zn-superoxide dismutase, a key enzyme in endogenous defenses against
oxidative stress. Their conclusion was that cannabinoids with anti-oxidant, cannabi-
noid-receptor-independent properties provide neuroprotection against the progressive
degeneration of nigrostriatal dopaminergic neurons occurring in PD.
The possible neuroprotective mechanism of CBD, highlighting the importance of
this compound to inhibit b-amyloid-induced neurodegeneration related to AD, has
been studied in cultured rat pheocromocytoma PC12 cells [44]. First, following
exposure of cells to b-amyloid peptide (1 mg/ml), a marked reduction in cell survival
was observed. This effect was associated with increased ROS production and lipid
peroxidation, as well as appearance of caspase-3 (a key enzyme in the apoptosis cell-
signaling cascade) , DNA fragmentation, and increased intracellular calcium. Treat-
ment of the cells with CBD prior to the amyloid-peptide exposure significantly elevated
cell survival, while it decreased ROS production, lipid peroxidation, caspase-3 levels,
DNA fragmentation, and intracellular calcium. These results indicated that CBD
exerted a combination of neuroprotective, anti-oxidative, and anti-apoptotic effects
against b-amyloid-peptide toxicity, and that inhibition of caspase-3 appearance from its
inactive precursor, pro-caspase-3, by CBD is involved in the signaling pathway for this
neuroprotection.
In a further study [45] [46], the same authors found that stimulation of differ-
entiated PC12 cells with Ab(1 – 42) (1 mg/ml) for 36 h caused a significant increase of
nitrite production, compared to non-stimulated cells. This production was inhibited in a
concentration-dependent manner by both the non-selective iNOS inhibitor l-NAME
(0.3 – 30 mm) , and by the selective iNOS inhibitor SMT (0.3 – 30 mm). CBD (10 6–104
m) inhibited both nitrite production and iNOS protein expression induced by Ab(1 –
42) . The CBD effect was mediated by inhibition of the phosphorylated form of the p38-
MAP kinase and the transcription factor nuclear-factor-kB(NF-kB) activation in a
concentration-dependent manner. These data are of considerable importance as a new
route to inhibit b-amyloid-induced neurodegeneration, which is a typical sign of AD.
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007)1686
5.2. Cerebral Ischemia. The anti-oxidative and anti-inflammatory properties of
CBD (2) led Braida et al. [47] to investigate its possible activity in preventing damage
caused by cerebral ischemia. CBD (1.25 – 20 mg/kg) was administered to gerbils 5 min
after a 10-min bilateral carotid-artery occlusion in freely-moving gerbils. Seven days
after ischemia, it antagonized electroencephalographic flattening, with a dose-depend-
ent bell-shaped curve, as seen in numerous other in vivo effects with CBD. The best
neuroprotective effect was noted at 5 mg/kg. Histological examination showed
complete survival of CA1 neurons in CBD-treated gerbils. These findings suggest a
potential therapeutic role of CBD in cerebral ischemia. The mechanism of the
protective action is not clear.
In a series of publications, Fujiwara and co-workers at Fukuoka University
investigated the reduction of damage of cerebral infarction in mice upon treatment
with CBD [12] [48]. They noted that CBD significantly decreased infarct volume after
cerebral-artery occlusion, which was not inhibited by a CB1antagonist, and was
independent of hypothermia. However, as mentioned above, the CBD effect was
blocked by a 5-HT1A antagonist. A recent publication by the same group [49] discloses
that, while repeated treatment with THC (1) leads to the development of tolerance, this
phenomenon is not observed with CBD (2).
5.3. Type-1 Diabetes. The therapeutic effects of CBD (2) in a model of rheumatoid
arthritis, an autoimmune disease, led our group to investigate its action in a related
disease, type-1 diabetes [50] . We found that CBD treatment of NOD mice
4
) before the
development of the disease reduced the incidence from 86% in the non-treated control
mice to 30% in CBD-treated mice. CBD Treatment also resulted in significant
reduction of plasma levels of the pro-inflammatory cytokines, IFN-gand TNF-a. Th1-
Associated cytokine production of in vitro activated T-cells and peritoneal macro-
phages was also significantly reduced in CBD-treated mice, whereas production of the
Th2-associated cytokines IL-4 and IL-10 was increased, when compared to untreated
control mice. Histological examination of the pancreatic islets of CBD-treated mice
revealed significantly reduced insulitis. These data indicate that CBD can inhibit and
delay destructive insulitis and inflammatory Th1-associated cytokine production in
NOD mice, resulting in a decreased incidence of diabetes, possibly through an
immunomodulatory mechanism shifting the immune response from Th1 to Th2
dominance.
In another publication recently submitted [51] , we show that administration of
CBD to female NOD mice, either in a latent diabetes stage (after 14 weeks) or with
initial symptoms of diabetes (appearing up to 14 weeks) , ameliorates the manifes-
tations of the disease. Diabetes was diagnosed in only 32% of the mice in the CBD-
treated group, compared to 100% in untreated groups. In addition, the level of the pro-
inflammatory cytokine IL-12 produced by splenocytes was significantly reduced,
whereas the level of the anti-inflammatory IL-10 was significantly elevated after CBD
treatment. Histological examination of the pancreas of CBD-treated mice revealed
more intact islets than in the controls. Our data strengthen the previous assumption that
CBD, known to be safe in man, can possibly be used as a therapeutic agent for
treatment of type-1 diabetes.
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007) 1687
4) Non-obese diabetes-prone mice that spontaneously develop diabetes.
The protective effects of CBD were also examined in streptozotocin-induced
diabetic rats after one, two, or four weeks [52]. Retinal cell death, blood-retinal-barrier
function, and oxidative stress were investigated by a variety of assays. Experimental
diabetes induced significant increases in oxidative stress, retinal neuronal cell death,
and vascular permeability. These effects were associated with increased levels of TNF-
a, vascular endothelial growth factor (VEGF) , intercellular adhesion-molecule-1, and
activation of p38-MAP kinase. CBD Treatment significantly reduced oxidative stress,
decreased the levels of TNF-a, VEGF, and intercellular adhesion-molecule-1, and
prevented retinal cell death and vascular hyperpermeability in the diabetic retina.
Consistent with these effects, CBD treatment also significantly inhibited p38-MAP
kinase in the retina. These results demonstrate that CBD treatment reduces neuro-
toxicity, inflammation, and blood-retinal-barrier breakdown in diabetic animals
through activities that may involve inhibition of p38-MAP kinase.
5.4. Anti-Emetic and Antinausea Effects. In a series of publications, in part reviewed
previously [7], a Canadian group led by Linda Parker [53] reported that CBD (2)
interferes with nausea in rats. THC (1) as well as CBD (2) were also found to potentiate
extinction of a cocaine- and an amphetamine-induced conditioned place preference in
rats. The cannabinoids did not affect learning or retrieval, and CBD was not hedonic on
its own. These results are the first to show that both THC, which acts on both CB1and
CB2receptors, and CBD, which does not bind to CB1or CB2receptors, potentiate the
extinction of conditioned incentive learning [53].
As rats do not vomit, a better model for vomiting was sought. The house musk
shrew (Suncus murinus) was found to be a suitable model, as it both vomits and
expresses nausea [54] . In this model, inhibition of anticipatory nausea based on the
emetic reactions of this mouse species was described [55]. Following three pairings of a
novel distinctive contextual cue with the emetic effects of an injection of LiCl, the
context acquired the potential to elicit conditioned retching in the absence of the toxin.
The expression of this conditioned retching reaction was completely suppressed by
pretreatment with each of the principal cannabinoids 1and 2found in marijuana, at a
dose that did not suppress general activity. On the other hand, pretreatment with a dose
of ondansetron (a 5-HT3 antagonist) , that interferes with acute vomiting in this species,
did not suppress the expression of conditioned retching during re-exposure to the Li-
paired context. These results support anecdotal claims that marijuana, but not
ondansetron, suppress the expression of anticipatory nausea.
5.5. Anxiety. Over the last two decades, numerous publications have examined the
effect of CBD (2) in various anti-anxiety models (for a review, see [7] ) . A recent
investigation using functional neuro-imaging has now given anatomical/physiological
support to the previous positive reports [56] . Regional cerebral-blood flow was
measured at rest using Single-Photon-Emission-Computed Tomography (SPECT ) in
ten healthy male volunteers, randomly divided into two groups of five subjects. The
reactions of each subject were evaluated on two occasions, one week apart. In the first
session, the subjects were given an oral dose of CBD (400 mg) or placebo, in a double-
blind procedure. SPECT Images were acquired 90 min after drug ingestion. The Visual
Analogue Mood Scale (VAMS) was applied to assess subjective states. In the second
session, the same procedure was performed with the drug that had not been
administered in the previous session. Comparisons of regional cerebral blood flow
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007)1688
were performed using suitable statistics. CBD significantly decreased subjective
anxiety, and increased mental sedation, while placebo did not induce significant
changes. Brain regions where anxiolytic effects of CBD were noted included the left
amygdala – hippocampal complex, extending into the hypothalamus, and the left
posterior cingulate gyrus. There was also greater activity with CBD than placebo in the
left parahippocampal gyrus. These results confirm that CBD has anxiolytic properties,
and that these effects are mediated by an action on limbic and paralimbic brain areas.
5.6. Rheumatoid Arthritis. The effect of CBD (2) was examined in two models of
rheumatoid arthritis [10] , both based on immunizing DBA/1 mice with type-II collagen
(CII) in complete Freunds adjuvant. The CII used was either bovine or murine,
resulting in classical acute collagen-induced arthritis (CIA) or in chronic relapsing
CIA, respectively. CBD was administered after onset of clinical symptoms. In both
models, treatment effectively blocked the progression of arthritis. CBD was equally
effective when administered i.p. or orally. The dose dependency showed a bell-shaped
curve, with an optimal effect at 5 mg/kg per day (i.p.), or at 25 mg/kg per day (orally) .
Clinical improvement was associated with protection of the joints against severe
damage. As mentioned above, draining lymph-node cells from CBD-treated mice
showed a diminished CII-specific proliferation and IFN-gproduction, as well as a
decreased release of TNF-aby synovial cells. These data show that CBD, through its
combined immunosuppressive and anti-inflammatory actions, has a potent anti-
arthritic effect in CIA.
In a later paper by the same group [57], using the same methods, related, though
more potent, effects were found with a CBD-derived synthetic material, HU-320 (()-
6b; see formula above) . The authors concluded that the profound suppressive effects
on cellular immune responses and on the production of pro-inflammatory mediators all
indicated the usefulness of HU-320 as a novel non-psychoactive, synthetic, anti-
inflammatory drug.
5.7. Cancer. The first documented experiments on the effects of CBD (2) on cancer
cells were performed in the 1970s. The authors either found tumor-promoting or no
effects at all. As these experiments were performed at extremely high doses (e.g.,
200 mg/kg [58]), it is unlikely that these observations are relevant to the current use of
CBD in clinical trials or with the approved drug Sativex, which contains CBD.
In the last years, there has been renewed interested in CBD as a potential
anticancer drug. Although Jacobsson et al. did not find any significant effects on C6 rat
glioma cells at CBD concentrations of up to 3 mm[59], it was later shown that this drug
is able to inhibit the growth of two different human glioma cells in nude mice, both in
vitro and in vivo.TheIC50 value for the two cell lines was ca.25mm, and apoptopic cell
death was observed by two different assays. The cytotoxic effects could be blocked by a
selective CB1antagonist, but only partially by a CB2antagonist. Surprisingly, pertussis
toxin, which inactivates the known cannabinoid receptors, had no influence. The exact
mechanism is not clear, as a vanilloid-receptor antagonist and inhibitors of ceramide
generation, which are responsible for some of the cytotoxic effects of THC (1), failed to
inhibit cell death [60] .
These observations were further investigated, and it was found that CBD has an
IC50 value of 6 – 11 mmtoward eight tumor cell lines, concentrations above 25 mm
seemingly being cytotoxic on healthy cell lines. Depending on the cell type, pro-
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007) 1689
apoptopic effects, cell-cycle arrest, and activation of caspase-3 were observed. As CBD
inhibits anandamide uptake, it was assumed that the observed cytotoxicity might be
caused by elevated anandamide levels, but more-efficient uptake inhibitors were not
cytotoxic. The hypothesis that cell death was induced by oxidative stress was further
supported by the cell-protective effects of the known anti-oxidants a-tocopherol
(vitamin E) and ascorbic acid (vitamin C ) , as well as by the observation that the
formation of ROS depended both on intra- and extracellular calcium. The formation of
ROS causes apoptosis, and when caspase-3 was inhibited, CBD was no longer effective.
The potential use of CBD as an anticancer drug was further shown with two different
tumor cell lines transplanted to nude mice. The tumors of the treated group were half as
big as those of the untreated group, and both breast- and lung-cancer cells injected to
paws showed approximately three times less metastatic invasion [61] . The effects of
CBD on glioma cells was selective, as it did not cause apoptosis in primary glial cells [62].
CBD also caused apoptosis in human myeloblastic leukemia cells. At the highest
tested concentration (8 mg/ml), 61% of the cells underwent apoptosis. This could be
increased to 93%, when the cells were exposed to g-radiation before CBD treatment.
Interestingly, CBD, either with or without irradiation, did not cause apoptosis in
healthy mononuclear cells [63] . This observation was confirmed by McKallip et al. [64],
and the possible mechanisms were studied. Activation of caspases-3, -8, and -9,
cleavage of poly(ADP-ribose) polymerase, and decreased levels of full-length Bid
might present a cross-talk between the intrinsic and extrinsic pathways of apoptosis. As
these effects could be blocked by the CB2antagonist SR144528, but not through a
general inhibition of the Gi/Go pathway of CB2receptors by pertussis toxin, it might be
postulated that SR144528 and CBD share an unknown binding site. However, another
study showed no influence by CB2blockade on the cytotoxic effects of CBD [65]. In
addition to these observed effects, the authors also showed increased expression of
NAD(P)H oxidases. Induction of apoptosis and cell death was also present in vivo [64].
One of the resistance mechanisms of cancer cells is the overexpression of the ATP-
binding cassette transporter, P-glycoprotein (P-gp) , which effluxes several anticancer
drugs. CBD at concentrations of up to 10 mmwas not able to inhibit P-gp, but 1 mmCBD
reduced the expression of P-gp by ca. 50%. In a cell line overexpressing P-gp, 10 mm
CBD increased the cytotoxicity of vinblastine (a P-gp substrate) threefold [66]. These
results are in contradiction to a second study [67], in which it was shown that CBD
inhibits P-gp (IC50 ¼8.44 mm) , while THC (1), THC-COOH, and CBN did not
significantly inhibit P-gp. Co-incubation of doxorubicin (a P-gp substrate and
anticancer drug) with CBD showed a decreased efflux of doxorubicin, and increased
intracellular concentrations. These different results might be due to the use of different
cell lines expressing P-gp.
R. M. is grateful to the National Institute on Drug Abuse, U.S.A., for support over many decades.
R. M. also kindly acknowledges a scholarship by the Lesmuller Foundation.
REFERENCES
[1] R. G. Pertwee, R. A. Ross, S. J. Craib, A. Thomas, Eur. J. Pharmacol. 2002,456,99.
[2] R. G. Pertwee, Euphytica 2004,140, 73.
[3] E. Russo, G. W. Guy, Medical Hypotheses 2006,66, 234.
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007)1690
[4] L. E. Long, D. T. Malone, D. A. Taylor, Drugs of the Future 2005,30, 747.
[5] A. W. Zuardi, F. S. Guimaraes, V. M. C. Guimaraes, E. A. Del Bel, Cannabidiol: Possible
Therapeutic Application, in Cannabis and Cannabinoids, Eds. F. Grotenhermen, E. Russo,
Haworth Press, Binghamton, N.Y., 2002, pp. 359– 369.
[6] R. Mechoulam, L. Hanus
ˇ,Chem. Phys. Lipids 2002,121, 35.
[7] R. Mechoulam, L. A. Parker, R. Gallily, J. Clin. Pharmacol.2002,42, 11S.
[8] A. Thomas, G. L. Baillie, A. M. Phillips, R. K. Razdan, R. A. Ross, R. G. Pertwee, Br. J. Pharmacol.
2007,150, 613.
[9] E. J. Carrier, J. A. Auchampach, C. J. Hillard, Proc. Natl. Acad. Sci. U.S.A. 2006,103, 7895.
[10] A. M. Malfait, R. Gallily, P. F. Sumariwalla, A. S. Malik, E. Andreakos, R. Mechoulam, M.
Feldmann, Proc. Natl. Acad. Sci. U.S.A. 2000,97, 9561.
[11] E. B. Russo, A. Burnett, B. Hall, K. K. Parker, Neurochem. Res. 2005,30, 1037.
[12] K. Mishima, K. Hayakawa, K. Abe, T. Ikeda, N. Egashira, K. Iwasaki, M. Fujiwara, Stroke 2005,36,
1077.
[13] N. Eshhar, S. Striem, R. Kohen, O. Tirosh, A. Biegon, Eur. J. Pharmacol. 1995,283,19.
[14] A. J. Hampson, M. Grimaldi, J. Axelrod, D. Wink, Proc. Natl. Acad. Sci. U.S.A. 1998,95, 8268.
[15] C. Hamelink, A. Hampson, D. A. Wink, L. E. Eiden, R. L. Eskay, J. Pharmacol. Exp. Ther. 2005,314,
780.
[16] Y. Kobayashi, A. Takeuchi, Z.-G. Wang, Org. Lett.2006,8, 2699.
[17] S. H. Baek, M. Srebnik, R. Mechoulam, Tetrahedron Lett. 1995,26, 1083.
[18] B. M. Trost, K. Dogra, Org. Lett. 2007,9, 861.
[19] A. Thomas, R. A. Ross, B. Saha, A. Mahadevan, R. K. Razdan, R. G. Pertwee, Eur. J. Pharmacol.
2004,487, 213.
[20] N. M. Kogan, C. Blazquez, L. Alvarez, R. Gallily, M. Schlesinger, M. Guzman, R. Mechoulam, Mol.
Pharmacol. 2006,70,51.
[21] N. M. Kogan, M. Schlesinger, E. Priel, R. Rabinowitz, E. Berenshtein, M. Chevion, R. Mechoulam,
Mol. Cancer Ther. 2007,6, 173.
[22] S. Tchilibon, R. Mechoulam, Org. Lett. 2000,2, 3301.
[23] L. Hanus
ˇ, S. Tchilibon, D. E. Ponde, A. Breuer, E. Fride, R. Mechoulam, Org. Biomol. Chem. 2005,
3, 1116.
[24] T. Bisogno, L. Hanus
ˇ, L. De Petrocellis, S. Tchilibon, D. Ponde, I. Brandi, A. S. Moriello, J. B. Davis,
R. Mechoulam, V. Di Marzo, Br. J. Pharmacol. 2001,134, 845.
[25] E. Fride, C. Feigin, D. E. Ponde, A. Breuer, L. Hanus
ˇ, N. Arshavsky, R. Mechoulam, Eur. J.
Pharmacol. 2004,506, 179.
[26] S. Ben-Shabat, L. Hanus
ˇ, G. Kazavian, R. Gallily, J. Med. Chem. 2006,49, 1113.
[27] J. Mannila, T. Jrvinen, K. Jrvinen, P. Jarho, J. Pharm. Sci. 2007,96, 312.
[28] M. Kathmann, K. Flau, A. Redmer, C. Traenkle, E. Schlicker, Naunyn-Schmiedeberg<s Arch.
Pharmacol. 2006,372, 354.
[29] P. Sacerdote, C. Martucci, A. Vaccani, F. Bariselli, A. E. Panerai, A. Colombo, D. Parolaro, P. Massi,
J. Neuroimmunol. 2005,159,97.
[30] B. L. F. Kaplan, C. E. Rockwell, N. E. Kaminski, J. Pharmacol. Exp. Ther. 2003,306, 1077.
[31] E. A. Formukong, A. T. Evans, F. J. Evans, Inflammation 1988,12, 361.
[32] B. Watzl, P. Scuderi, R. R. Watson, Int. J. Immunopharmacol. 1991,13, 1091.
[33] M. D. Srivastava, B. I. S. Srivastava, B. Brouhard, Immunopharmacology 1998,40, 179.
[34] I. Feinberg, R. Jones, J. Walker, C. Cavness, T. Floyd, Clin. Pharmacol. Ther. 1976,19, 782.
[35] J. M. Monti, Psychopharmacology 1977,55, 263.
[36] E. A. Carlini, J. M. Cunha, J. Clin. Pharmacol. 1981,21, 417S.
[37] A. N. Nicholson, C. Turner, B. M. Stone, P. J. Robson, J. Clin. Psychopharmacol. 2004,24, 305.
[38] E. Murillo-Rodriguez, D. Millan-Aldaco, M. Palomero-Rivero, R. Mechoulam, R. Drucker-Colin,
FEBS Lett.2006,580, 4337.
[39] G. Tanda, F. E. Pontieri, G. Di Chiara, Science 1997,276, 2048.
[40] D. T. Malone, D. A. Taylor, Br. J. Pharmacol.1999,128,21.
[41] V. M. C. Guimaraes, A. W. Zuardi, E. A. Del Bel, F. S. Guimaraes, Life Sci. 2004,75, 633.
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007) 1691
[42] I. Lastres-Becker, F. Molina-Holgado, J. A. Ramos, R. Mechoulam, J. Fernandez-Ruiz, Neurobiol.
Dis.2005,19,96.
[43] M. Garcia-Arencibia, S. Gonzalez, E. de Lago, J. A. Ramos, R. Mechoulam, J. Fernandez-Ruiz,
Brain Res. 2007,1134, 162.
[44] T. Iuvone, G. Esposito, R. Esposito, R. Santamaria, M. Di Rosa, A. A. Izzo, J. Neurochem. 2004,89,
134.
[45] G. Esposito, D. Filippis, R. Carnuccio, A. A. Izzo, T. Iuvone, J. Mol. Med. 2006,84, 253.
[46] G. Esposito, D. De Filippis, M. C. Maiuri, D. De Stefano, R. Carnuccio, T. Iuvone, Neurosci. Lett.
2006,399,91.
[47] D. Braida, S. Pegorini, M. V. Arcidiacono, G. G. Consalez, L. Croci, M. Sala, Neurosci. Lett. 2003,
346,61.
[48] K. Hayakawa, K. Mishima, K. Abe, N. Hasebe, F. Takamatsu, H. Yasuda, T. Ikeda, K. Inui, N.
Egashira, K. Iwasaki, M. Fujiwara, Neuroreport 2004,15, 2381.
[49] K. Hayakawa, K. Mishima, M. Nozako, A. Ogata, M. Hazekawa, A. X. Liu, M. Fujioka, K. Abe, N.
Hasebe, N. Egashira, K. Iwasaki, M. Fujiwara, Neuropharmacology 2007,52, 1079.
[50] L. Weiss, M. Zeira, S. Reich, M. Har-Noy, R. Mechoulam, S. Slavin, R. Gallily, Autoimmunity 2006,
39, 143.
[51] L. Weiss, submitted for publication.
[52] A. B. El-Remessy, M. Al-Shabrawey, Y. Khalifa, N.-T. Tsai, R. B. Caldwell, G. I. Liou, Am. J. Pathol.
2006,168, 235.
[53] L. Parker, P. Burton, R. Sorge, C. Yakiwchuk, R. Mechoulam, Psychopharmacology 2004,175, 360.
[54] L. A. Parker, M. Kwiatkowska, P. Burton, R. Mechoulam, Psychopharmacology 2004,171, 156.
[55] L. A. Parker, M. Kwiatkowska, R. Mechoulam, Physiol. Behav.2006,87, 66.
[56] J. A. de S. Crippa, J. A. W. Zuardi, G. E. J. Garrido, L. Weichert-Ana, G. L. Ferrari, P. M. Azevedo-
Marques, J. E. C. Hallak, P. K. McGuire, G. F. Busatto, Neuropsychopharmacology 2004,29, 417.
[57] P. F. Sumariwalla, R. Gallily, S. Tchilibon, E. Fride, R. Mechoulam, M. Feldmann, Arthritis
Rheumatism 2004,50, 985.
[58] A. N. Tucker, M. A. Friedman, Res. Commun. Chem. Pathol. Pharmacol. 1977,17, 703.
[59] S. O. Jacobsson, E. Rongard, M. Stridh, G. Tiger, C. J. Fowler, Biochem. Pharmacol. 2000,60, 1807.
[60] P. Massi, A. Vaccani, S. Ceruti, A. Colombo, M. P. Abbracchio, D. J. Parolaro, Pharmacol. Exp. Ther.
2004,308, 838.
[61] A. Ligresti, A. S. Moriello, K. Starowicz, I. Matias, S. Pisanti, L. De Petrocellis, C. Laezza, G.
Portella, M. Bifulco, V. Di Marzo, J. Pharmacol. Exp. Ther. 2006,318, 1375.
[62] P. Massi, A. Vaccani, S. Bianchessi, B. Costa, P. Macchi, D. Parolaro, Cell. Mol. Life Sci.2006,63,
2057.
[63] R. Gallily, T. Even-Chen, G. Katzavian, D. Lehmann, A. Dagan, R. Mechoulam, Leukemia
Lymphoma 2003,44, 1767.
[64] R. J. McKallip, W. Jia, J. Schlomer, J. W. Warren, P. S. Nagarkatti, M. Nagarkatti, Mol. Pharmacol.
2006,70,897.
[65] A. Vaccani, P. Massi, A. Colombo, T. Rubino, D. Parolaro, Br. J. Pharmacol. 2005,144, 1032.
[66] M. L. Holland, J. A. Panetta, J. M. Hoskins, M. Bebawy, B. D. Roufogalis, J. D. Allen, J. C. Arnold,
Biochem. Pharmacol.2006,71, 1146.
[67] H.-J. Zhu, J.-S. Wang, J. S. Markowitz, J. L. Donovan, B. B. Gibson, H. A. Gefroh, C. L. DeVane, J.
Pharmacol. Exp. Ther. 2006,317, 850.
Received March 29, 2007
CHEMISTRY & BIODIVERSITY – Vol. 4 (2007)1692
