(+)-trans-Cannabidiol-2-hydroxy pentyl is a dual CB1R antagonist/CB2R agonist that prevents diabetic nephropathy in mice

Article abstract of DOI:10.1016/j.phrs.2021.105492

Natural cannabidiol ((-)-CBD) and its derivatives have increased interest for medicinal applications due to their broad biological activity spectrum, including targeting of the cannabinoid receptors type 1 (CB₁R) and type 2 (CB₂R). Herein, we synthesized the (+)-enantiomer of CBD and its derivative (+)-CBD hydroxypentylester ((+)-CBD-HPE) that showed enhanced CB₁R and CB₂R binding and functional activities compared to their respective (-) enantiomers. (+)-CBD-HPE Ki values for CB₁R and CB₂R were 3.1 ± 1.1 and 0.8 ± 0.1 nM respectively acting as CB₁R antagonist and CB₂R agonist. We further tested the capacity of (+)-CBD-HPE to prevent hyperglycemia and its complications in a mouse model. (+)-CBD-HPE significantly reduced streptozotocin (STZ)-induced hyperglycemia and glucose intolerance by preserving pancreatic beta cell mass. (+)-CBD-HPE significantly reduced activation of NF-κB by phosphorylation by 15% compared to STZ-vehicle mice, and CD3⁺ T cell infiltration into the islets was avoided. Consequently, (+)-CBD-HPE prevented STZ-induced apoptosis in islets. STZ induced inflammation and kidney damage, visualized by a significant increase in plasma proinflammatory cytokines, creatinine, and BUN. Treatment with (+)-CBD-HPE significantly reduced 2.5-fold plasma IFN-γ and increased 3-fold IL-5 levels compared to STZ-treated mice, without altering IL-18. (+)-CBD-HPE also significantly reduced creatinine and BUN levels to those comparable to healthy controls. At the macroscopy level, (+)-CBD-HPE prevented STZ-induced lesions in the kidney and voided renal fibrosis and CD3⁺ T cell infiltration. Thus, (+)-enantiomers of CBD, particularly (+)-CBD-HPE, have a promising potential due to their pharmacological profile and synthesis, potentially to be used for metabolic and immune-related disorders.

Full text of DOI:10.1016/j.phrs.2021.105492

Pharmacological Research 169 (2021) 105492
Contents lists available at ScienceDirect
Pharmacological Research
journal homepage: www.elsevier.com/locate/yphrs
(+)-trans-Cannabidiol-2-hydroxy pentyl is a dual CB1R antagonist/CB2R
agonist that prevents diabetic nephropathy in mice
a
,
Isabel Gonzalez-Mariscal *, Beatriz Carmona-Hidalgob, Matthias Winklerc,
´
b
d
e
e
´
˜
´
Juan D. Unciti-Broceta , Alejandro Escamilla , María Gomez-Canas , Javier Fernandez-Ruiz ,
Bernd L. Fiebichf, Silvana-Yanina Romero-Zerboa, Francisco J. Bermúdez-Silvaa
,
,
g
Juan A. Colladoh , Eduardo Munoz
,
i,
j
h,i,j,**
˜
a
´
´
´
´
´
´
Instituto de Investigacion Biomedica de Malaga-IBIMA, UGC Endocrinología y Nutricion, Hospital Regional Universitario de Malaga, 29009 Malaga, Spain
b
´
Emerald Health Biotechnology, Cordoba, Spain
c Symrise AG, Holzminden, Germany
d Microscopy platform, IBIMA, Malaga, Spain
e
´
Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Investigacion en Neuroquímica, Universidad Complutense,
CIBERNED and IRYCIS, Madrid, Spain
f VivaCell Biotechnology GmbH, Dezlingen, Germany
g
´
´
´
Centro de Investigacion Biomedica en Red de Diabetes y Enfermedades Metabolicas Asociadas (CIBERDEM), Madrid, Spain
h
i
´
´
´
´
Instituto Maimonides de Investigacion Biomedica de Cordoba, Spain
´
´
Departamento de Biología Celular, Fisiología e Inmunología, Universidad de Cordoba, 14004 Cordoba, Spain
j
´
Hospital Universitario Reina Sofía, Cordoba, Spain
A R T I C L E I N F O
A B S T R A C T
Keywords:
Natural cannabidiol ((-)-CBD) and its derivatives have increased interest for medicinal applications due to their
broad biological activity spectrum, including targeting of the cannabinoid receptors type 1 (CB1R) and type 2
(CB2R). Herein, we synthesized the (+)-enantiomer of CBD and its derivative (+)-CBD hydroxypentylester
((+)-CBD-HPE) that showed enhanced CB1R and CB2R binding and functional activities compared to their
respective (-) enantiomers. (+)-CBD-HPE Ki values for CB1R and CB2R were 3.1 ± 1.1 and 0.8 ± 0.1 nM
respectively acting as CB1R antagonist and CB2R agonist. We further tested the capacity of (+)-CBD-HPE to
prevent hyperglycemia and its complications in a mouse model. (+)-CBD-HPE significantly reduced streptozo-
tocin (STZ)-induced hyperglycemia and glucose intolerance by preserving pancreatic beta cell mass. (+)-CBD-
HPE significantly reduced activation of NF-κB by phosphorylation by 15% compared to STZ-vehicle mice, and
CD3+ T cell infiltration into the islets was avoided. Consequently, (+)-CBD-HPE prevented STZ-induced
apoptosis in islets. STZ induced inflammation and kidney damage, visualized by a significant increase in
plasma proinflammatory cytokines, creatinine, and BUN. Treatment with (+)-CBD-HPE significantly reduced 2.5-
fold plasma IFN-γ and increased 3-fold IL-5 levels compared to STZ-treated mice, without altering IL-18.
(+)-CBD-HPE also significantly reduced creatinine and BUN levels to those comparable to healthy controls. At
the macroscopy level, (+)-CBD-HPE prevented STZ-induced lesions in the kidney and voided renal fibrosis and
CD3+ T cell infiltration. Thus, (+)-enantiomers of CBD, particularly (+)-CBD-HPE, have a promising potential
due to their pharmacological profile and synthesis, potentially to be used for metabolic and immune-related
disorders.
Cannabidiol
(+)-enantiomers
Cannabinoids
Cannabinoid 1 receptor
Cannabinoid 2 receptor
Diabetic nephropathy
Type 1 diabetes
Abbreviations: CBD, Cannabidiol; CB1R and CB2R, Cannabinoid receptors type 1 and 2; NAM, Negative allosteric modulator; T1D, Type 1 diabetes; NOD, Non-
obese diabetic mice; CRE, cAMP response element; STZ, Streptozotocin; PAS, Periodic Acid Schiff; PSR, Picrosirius Red staining; BSA, Bovine serum albumin; BUN,
Blood urea nitrogen.
* Corresponding author.
´
´
** Corresponding author at: Departamento de Biología Celular, Fisiología e Inmunología, Universidad de Cordoba,14004 Cordoba, Spain.
´
˜
E-mail addresses: isabel.gonzalez@ibima.eu (I. Gonzalez-Mariscal), fi1muble@uco.es (E. Munoz).
https://doi.org/10.1016/j.phrs.2021.105492
Received 23 November 2020; Received in revised form 21 January 2021; Accepted 11 February 2021
Available online 19 May 2021
1043-6618/© 2021 Elsevier Ltd. All rights reserved.

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I. Gonzalez-Mariscal et al.
Pharmacological Research 169 (2021) 105492
1. Introduction
2. Material and methods
The most occurring non-psychotropic cannabinoid found in Cannabis
sativa, cannabidiol (CBD), has increased interest for medicinal applica-
tions due to its broad biological activity spectrum (reviewed in [1]). The
use of CBD preparations is becoming popular with dozens of products
already in the market claiming different health benefits based on
anecdotal evidence. More importantly, CBD is used in combination with
9Δ-Tetrahydrocannabinol (Sativex®) for the treatment of spasticity in
multiple sclerosis patients, and as a single drug (Epidiolex®) for the
treatment of refractory epilepsies in children [2,3]. A large number of
marketed drugs are based or inspired by natural products. This,
numerous CBD derivatives (e.g. fluorinated, hydroxyquinones, methyl-
ester, etc.) have been generated to improve its pharmacological prop-
erties [1].
2.1. Synthesis of (+)-CBD enantiomers
The schematic synthesis of (+)-CBD and (+)-CBD-HPE enantiomers
is shown in Fig. 1.
2.1.1. Synthesis of (+)-CBD ME (1)
71.4 g (300 mM) olivetol methyl ester and 50 g (330 mM) 1 R,4S-
menthadienol were dissolved together with toluene to reach a combined
volume of 400 mL (Solution A). 21.3 g (150 mM) BF3 etherate was
dissolved with toluene to reach a volume of 300 mL (Solution B). Both
reaction solutions were then put through two pump systems and the
continuous flow reactor (rotation: 1200 U/min, solution A: 24 mL/min,
solution B: 12 mL/min). Solution B started before and ended after so-
lution A to guarantee that catalyst is always present in the reaction
chamber. The reaction mixture was continuously collected in a 2-liter
lab reactor (30 ◦C mantel temperature, 300 rpm) filled with a 700 mL
saturated NaHCO3 solution. The aqueous solution was discarded; the
organic solution was washed at 45 ◦C 4 times with 250 mL of 1% NaOH
solution. After washing, the organic solution was evaporated to dryness
to give 94.58 g of raw (+)-CBD methyl ester (purity = 78%, yield 68%).
The raw compound was used further without purification.
The mechanism of action of CBD is not completely understood and
the signaling through canonical cannabinoid receptors type 1 and 2
(CB1R and CB2R) has been controversial. Nevertheless, CBD does not
bind to the orthosteric site of CB1R and it has been proposed that act as a
negative allosteric modulator (NAM) of CB1R, which may explain some
of the biological activities mediated by this cannabinoid [4].
Naturally occurring CBD has the absolute stereo conformation
(-)-trans. Cis-isomers or (+)-enantiomers are not produced in plants and
have, therefore, until now, no pharmaceutical impact. However, the
synthetic enantiomer (+)-trans-CBD binds to CB1R and CB2R at nano-
molar concentrations [5] but did not exhibit any effects in the tetrad
group of assays (ambulation, sedation, analgesia, temperature
lowering), which are typical for cannabinoid CB1R agonists [6].
Therefore, it is possible that (+)-trans-CBD does not penetrate the brain
or, more likely, does not behave as a full CB1R agonist. Interestingly,
(+)-trans-CBD has been used as a template to develop novel derivatives
with enhancing binding affinity to CB1R and CB2R. Among them,
(+)-Cannabidiol-dimethyl heptyl have shown to exert analgesic activity
[6,7].
2.1.2. Synthesis of (+)-CBD (3)
49.2 g (103 mM) (+)-CBD ME (1) was dissolved at 60 ◦C in 250 mL
ethylene glycol and poured in a 1 L lab reactor. 5.7 g potassium hy-
droxide was added, and the reaction mixture was started to heat under
stirring to 120 ◦C and a vacuum of 500 mbar. Accumulated volatile side
products were distilled off. After 2 h the reaction temperature was
increased to 150 ◦C and the temperature was kept for additional 3 h.
The reaction mixture was cooled to 80 ◦C, following addition of 400 mL
water and 130 mL n-heptane. The temperature was further decreased to
40 ◦C, following the slow addition of 1.2 mL of 50% sulfuric acid (50%)
until a pH of approx. 6. The layers were separated; the organic layer was
washed once with 250 mL of water and once with 250 mL of sodium
hydroxide solution (0.05%). The organic layer was dried over Na2SO4
and then evaporated to dryness. Yield: 30.3 g, GC purity: 53%. A sample
of the reaction mixture was taken after 2 h at 120 ◦C, quenched with n-
heptane and water and neutralized with sulfuric acid (10% w/w). The
layers were separated, and the organic layer was evaporated to dryness.
The crude (+)-CBD (3) was purified by flash chromatography (eluent
system cyclohexane / ethyl acetate = 20 / 1 v/v), following crystalli-
zation from n-heptane. GC purity: 99.8%. Chiral GC analysis: enantio-
meric excess 99% (for enantiomeric pure starting material and for
starting materials with up to 5% 4R-menthadienol enantiomer). 1H NMR
(400 MHz, CDCl3) δ 6.35 – 6.09 (m, 2H), 5.97 (s, 1H), 5.57 (dt, J = 2.8,
1.6Hz, 1H), 4.66 (p, J = 1.6 Hz, 2H), 4.56 (d, J = 2.0 Hz, 1H), 3.85
(ddp, J = 10.7, 4.5, 2.3 Hz, 1H), 2.48 – 2.41 (m, 2H), 2.38 (ddd,
J = 10.6, 3.7 Hz, 1H), 2.30 – 2.17 (m, 1H), 2.09 (ddt, J = 17.9, 5.1,
2.4 Hz, 1H), 1.88 – 1.81 (m, 1H), 1.79 (dt, J = 2.6, 1.2 Hz, 3H), 1.78 –
1.72 (m, 1H), 1.65 (t, J = 1.1 Hz, 3H), 1.62 – 1.50 (m, 2H), 1.37 – 1.22
(m, 4H), 0.88 (t, J = 7.0 Hz, 3H). 13C NMR (101 MHz, CDCl3) δ 156.07,
153.90, 149.41, 143.06, 140.07, 124.12, 113.76, 110.84, 109.84,
108.00, 7.35, 77.03, 76.71, 46.15, 37.28, 35.48, 31.50, 30.64, 30.41,
28.41, 23.69, 22.55, 20.54, 14.05 (Supplementary Fig. 1A).
We have recently shown that chemical modifications of (-)-CBD at
position 2 of the resorcinol moiety increased the binding of both CB1R
and CB2R. Thus, (-)-CBD-2-hydroxy pentyl ((-)-CBD-HPE) showed a
strong binding for CB2R and a moderate binding to CB1R. In functional
assays (-)-CBD-HPE behaved as an agonist for CB2R and antagonist for
CB1R [8]. Such pharmacological profile has been investigated for other
natural and synthetic cannabinoids, as it is known to impact metabolism
and immune action and has a great potential for the treatment of a wide
range of diseases. Type 1 diabetes (T1D) is an autoimmune disease with
no cure characterized by the infiltration of immune cells in and around
the islets, leading to the progressive loss of beta cell mass and hyper-
glycemia [9]. High blood glucose due to T1D increases the risk of macro
and microvascular complications, including renal failure [10]. CBD
delayed the onset of T1D in non-obese diabetic mice (NOD) [11], but the
impact of targeting CB1R and CB2R on T1D and its complications re-
mains unstudied. Antagonism of CB1R has been shown to alleviate ne-
phropathy in type 2 diabetic rats [12], and blockade or genetic ablation
of CB1R preserves insulin-producing pancreatic beta cell viability and
function and also prevents the infiltration of immune cells in and around
pancreatic islets in obese mice [13,14]. CB2R is mainly expressed in
immune cells, and its agonism reduces ROS production, cytokine
release, and immune cell proliferation [15].
In the present study, we first explored whether, as it happens with
(+)-trans-CBD [5], the synthesis of the (+)-enantiomer of CBD-HPE is
also accompanied by an increase in its binding activity on both CB1R and
CB2R, as well as in its activity as CB1R antagonist and CB2R agonist. As a
second objective, we have investigated the efficacy of this new (+)-CBD
derivative to ameliorate nephropathy in a murine model of T1D.
2.1.3. Synthesis of (+)-CBD-HPE (4)
10 g (24 mM) (+)-CBD ME (1) was dissolved at 60 ◦C in 250 mL 1,2-
pentanediol and poured in a 1 L lab reactor. 1.1 g potassium hydroxide
was added, and the reaction mixture was started to heat under stirring to
120 ◦C and a vacuum of 500 mbar. Accumulated volatile side products
were distilled off. After 2 h the reaction mixture was cooled to 80 ◦C,
following addition of 400 mL water and 130 mL n-hexane. The tem-
perature was further decreased to room temperature and neutralized
with sulfuric acid (10% w/w). The layers were separated; the organic
2

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Pharmacological Research 169 (2021) 105492
Fig. 1. Schematic representation of (+)-trans-CBD and (+)-CBD-HPE synthesis.
layer was washed once with 250 mL of water, dried over Na2SO4 and
CB1R or 0.53 nM for CB2R and in a final volume of 200 µl for both re-
ceptors. The reaction was stirred for 90 min at 30 ◦C. Non-specific
binding was determined with non-radiolabeled WIN55,212-2 (Sigma
Aldrich, 10 µM) in the presence of radioligand. 100% binding of the [3H]
CP-55,940 was determined by incubation of the membranes with radi-
oligand in the absence of the tested cannabinoids. All of the plastic
material employed was siliconized with Sigmacote (Sigma-Aldrich) to
prevent possible adhesion of compounds. After incubation, free radio-
ligand was separated from bound radioligand by filtration in GF/C fil-
ters, previously treated with a 0.05% (v v-1) polyethylethylenimine
solution. Then, filters were washed nine times with cold assay buffer,
using the Harvester® filtermate equipment (Perkin Elmer). Radioac-
tivity was measured using a liquid scintillation spectrometer (Microbeta
Trilux 1450 LSC & Luminiscence Counter (Perkin Elmer)). Data were
expressed as the percentage of [3H]CP-55,940 binding. Ki values were
obtained with GraphPad Prism (5.02) software (GraphPad Software Inc.,
San Diego, CA, USA).
evaporated to dryness. The crude product (+)-CBD HPE (4) was purified
by flash chromatography (eluent system cyclohexane
/ ethyl
acetate = 10 / 1 v/v). GC purity: 98%. Chiral GC analysis: enantio-
meric excess 99%. 1H NMR (400 MHz, DMSO-d6) δ 11.61 (s, 1H), 9.89
(s, 1H), 6.20 (s, 1H), 5.11 – 5.05 (m, 1H), 4.91 – 4.82 (m, 1H), 4.46 (d,
J = 2.7Hz, 1H), 4.42 (dd, J = 2.8, 1.5 Hz, 1H), 4.24 – 4.11 (m, 2H),
3.95 – 3.86 (m, 1H), 3.81 – 3.71 (m, 1H), 3.03 (td, J = 11.4, 10.9,
3.0 Hz, 1H), 2.74 (s, 2H), 2.22 – 2.05 (m, 1H), 1.94 (dd, J = 16.7,
4.1 Hz, 1H), 1.76 – 1.63 (m, 2H), 1.61 (t, J = 1.8 Hz, 3H), 1.58 (s, 3H),
1.53 – 1.34 (m, 6H), 1.33 – 1.26 (m, 4H), 0.89 (t, J = 7.0 Hz, 3H), 0.86
(t, J = 6.7 Hz, 3H). 13C NMR (101 MHz, DMSO-d6) δ 171.22, 162.07,
160.33, 148.61, 144.07, 130.72, 125.60, 114.82, 110.15, 109.84,
103.50, 68.95, 67.27, 43.32, 35.71, 35.61, 35.44, 31.36, 30.91, 30.13,
29.12, 23.13, 22.00, 18.88, 18.12, 13.86, 13 (Supplementary Fig. 1B).
2.2. CB1R and CB2R binding assay
Binding assays were investigated by competition studies against [3H]
CP-55,940 (164.5 Ci/mmol, Perkin Elmer, Boston, MA, USA) to deter-
mine its binding affinity (Ki value) at both cannabinoid receptors using
commercially available membranes prepared from CB1R- or CB2R-stably
transfected HEK-293 cells (RBHCB1M400UA and RBXCB2M400UA,
respectively; Perkin-Elmer) [16]. Briefly, membranes were added in
assay buffer (for CB1R: 50 mM Tris-Cl, 5 mM MgCl2⋅H2O, 2.5 mM EDTA,
0.5 mg mL-1 bovine serum albumin, pH 7.4, or for CB2R: 50 mM Tris-Cl,
5 mM MgCl2⋅H2O, 2.5 mM EGTA, 1 mg mL-1 bovine serum albumin, pH
7.5) at a final concentration of 8 µg/well and 4 µg/well for CB1R and for
CB2R receptors, respectively. The radioligand was used at 0.4 nM for
2.3. Transfections and luciferase assays
HEK-293 T (8 × 104) cells stably expressing human cannabinoid
CB1R or CB2R were seeded in 24-well plates and after 24 h were tran-
siently transfected with the pCRE-Luc plasmid (0.2 µg/well) using
Roti©-Fect (Carl Roth, Karlsruhe, Germany) following manufacturer´s
specifications. The CRE luciferase reporter contains the firefly luciferase
gene under the control of the multimerized cAMP response element
(CRE) located upstream of a minimal promoter. Twenty-four hours after
transfection, CB1R-HEK-293T cells were pretreated for 30 min with the
cannabinoids and stimulated with WIN55,212 (1 µM) for 6 h. CB2R-
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Pharmacological Research 169 (2021) 105492
HEK-293T cells were pretreated for 30 min with the cannabinoids or
WIN55,212 as positive control and stimulated with Forskolin (FSK)
Triton-X-100 in PBS overnight at 4 ◦C. Primary antibodies used were:
mouse anti-insulin (SIGMA I-2018; 1:500), rabbit anti-NF-kB p65
phospho-S536 (Abcam ab86299; 1:100), rabbit anti-cleaved caspase 3
(Cell signaling 9661; 1:100) and mouse anti-CD3 (Santa Cruz Bio-
technologies sc-20047; 1:50) for kidney and rabbit anti-CD3 (Abcam
ab5690; 1:100) for pancreas. Sections were washed 3 times for 5 min in
0.3% Triton-X-100 PBS and incubated with secondary antibody in 1%
serum or BSA, 0.3% Triton-X-100 in PBS for 30 min at 37 ◦C and then
washed 3 times for 5 min in 0.3% Triton-X-100 PBS. Alexa Fluor or HRP
polymer-conjugated antibodies were incubated for 45 min at 37 ◦C, and
nuclei stained using DAPI for immunofluorescence. DAB staining was
performed following hematoxylin for nuclei staining. Negative controls
were performed using 0.3% Triton-X-100 PBS containing 1% goat serum
or BSA. Imaging was performed at 20X using an Olympus BX41. The
densitometry of images was analyzed using ImageJ (NIH). DAB staining
was quantified using ImageJ Fiji after color deconvolution and further
processed by Image J software to quantify signal intensity. Cell count
was analyzed by a manual count of n = 100 islets per group.
(10 μM) for 6 h. After treatments, luciferase activity was measured using
Dual-Luciferase Assay (Promega, Madison, WI, USA).
2.4. Animals
Animal care and procedures were approved by the Animal Experi-
mentation Ethics Committee of the Malaga University and authorized by
the government of Andalucia (Project number 28/06/2018/107),
complied with the ARRIVE guidelines, and followed the EU Directive
2010/63/EU guidelines for animal experiments. C57BL6J mice (Charles
River France) were housed in groups of 10 using 12 h dark/light cycles
and provided food and water ad libitum. Eight- to 10-week-old C57BL6J
male mice of 24.4 ± 0.2 g of body weight were randomized to 3 groups:
healthy control (vehicle and citrate buffer), vehicle-streptozotocin
(STZ), and (+)-CBD-HPE-STZ. Mice were injected daily intraperitone-
ally (i.p.) with vehicle (saline:DMSO:Tween-80, 95:4:1) or 10 mg/kg of
(+)-CBD-HPE for 7 days. Mice were fasted for 4 h prior i.p. injections
with STZ or citrate buffer (healthy controls) as described previously
[17]. Mice were given 10% sucrose water for 48 h upon STZ treatment to
prevent ongoing toxicity and to avoid hypoglycemia. Blood glucose was
monitored daily using OneTouch Ultra blood glucose meter (LifeScan IP
Holdings, LLC). After 6 days mice were euthanized by cervical disloca-
tion, and tissues and blood were collected and processed immediately
for histological and biochemical analysis.
2.7. Plasma proteins and nitrogen determination
Cytokines in plasma were determined using the multiplex assay
ProcartaPlex Immunoassay (Thermo Fisher Scientific) designed for T1D
following manufacturer’s instructions. Cytokines bellow the standard
curve were discarded as non-detected. Blood urea nitrogen (BUN) and
creatinine were determined using DetectX BUN Detection Kit and
DetectX Creatinine Serum Kit (Arbor Assays) following the manufac-
turer’s instructions.
2.5. Intraperitoneal glucose tolerance test
Mice were fasted overnight and given free access to water. Mice were
given i.p. a bolus of 2 g/kg glucose and blood glucose was determined at
0, 15, 30, 60, and 90 min.
2.8. Randomization
Mice were randomly assigned to healthy control, vehicle-STZ, or
(+)-CBD-HPE-STZ groups.
2.6. Tissue immunohistochemistry and histochemistry
2.9. Blinding
Pancreas and kidney were dissected and fixed in methanol-free 4%
paraformaldehyde (Pierce) for 6 h at room temperature or 24 h at 4 ◦C,
Mice used in this study were assigned a numerical code and analysis
blinded.
respectively, prior paraffin embedding. Kidney sections (5
μm) were
deparaffinized and dehydrated in a graded series (100–70%) of ethanol
washes and stained with Periodic Acid Schiff (PAS) (Sigma-Aldrich, St.
Louis, MO, USA) to evaluate renal pathology. Two independent asses-
sors reviewed histological sections in a blinded manner and graded (0–3
scale) glomerular changes (hypercellularity, mesangial expansion, and
capillary dilation, 40 glomeruli), tubular lesions (atrophy and degen-
eration, 20 fields at 40x magnification), and interstitial damage (fibrosis
and inflammation, 20 fields at 40X magnification) (PMID: 27609616).
Imaging was performed using a light microscope Leica DM2000 mi-
croscope. Glomerular area and diameter were marked manually and
calculated automatically using Image J software (http://rsb.info.nih.
gov/.ij). Kidney collagen was detected by Picrosirius Red (PSR) stain-
ing (PSR) following the manufacturer´s instructions (Sigma-Aldrich).
Quantitative evaluation of PSR staining was estimated as the staining
under a grid intersection / total number of intersections multiplied by
100 (% of the fraction area), as described previously [18]. The data were
represented by the area percentage of each slide positive (20 fields at
40x magnification) for red stain which was calculated using Image J
software. The mean scores were calculated by mouse and by group. For
immunohistochemistry, heat-mediated citric acid- or EDTA-based for
20 min in a preheated steamer and a further 20 min of cooling down was
performed. For DAB staining, peroxidase activity was blocked in 3%
hydrogen peroxide for 10 min. For mouse-on-mouse staining, sections
were pre-blocked with Rodent Block (Biocare Medical) for 30 min at
room temperature and rinsed. Sections were blocked in 5% goat serum
0.3% Triton-X-100 in PBS or bovine serum albumin (BSA) 0.3%
Triton-X-100 in PBS for phospho-antibodies for 30 min at 37 ◦C prior
incubation with primary antibody in 1% serum or BSA, 0.3%
2.10. Statistical analysis
Data are shown as mean ± SEM. Statistical analysis was performed
using GraphPad Prism version 6.07. Mean values were compared using
ANOVA with Tukey’s or Dunn’s test for a parametric or non-parametric
test, respectively. A p-value < 0.05 was considered significant.
3. Results
3.1. Binding and functional activities of (+) enantiomers on cannabinoid
receptors
(+)-CBD and its derivatives (Fig. 1) were synthesized as described
above, with 99–98% purity and an enantiomeric excess of 99% (see
Supplementary Fig. 1 for NMR spectra). In order to characterize the
(+)-CBD and its derivative (+)-CBD-HPE and to compare with synthetic
(-)-CBD and (-)-CBD-HPE (2-HPC in [8]) we explored their binding
capability to CB1R and CB2R. As shown in Table 1, (-)-CBD presented a
Table 1
Binding of (-) and (+)-enantiomers of CBD to CB1R and CB2R.
Compound
CB1R-Ki (nM)
CB2R-Ki (nM)
CB1R/CB2R selectivity
(-)-CBD
8960 ± 371
982 ± 306
538 ± 54
4310 ± 1292
40.5 ± 7.3
66.7 ± 13.1
0.8 ± 0.1
2.1
24.3
8.1
(+)-CBD
(-)-CBD-HPE
(+)-CBD-HPE
3.1 ± 1.1
3.9
4

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Pharmacological Research 169 (2021) 105492
low binding activity on both CB1R and CB2R (Table 1), and, as expected,
the enantiomer (+)-CBD showed a higher binding activity for both re-
ceptors (Table 1). (-)-CBE-HPE showed an increased binding affinity
CB1R and CB2R compared to (-)-CBD (data from [8]; Table 1). Impor-
tantly, (+)-CBE-HPE presented a very potent binding affinity for the
cannabinoid receptors, with 2.9 × 103-fold and 5.3 × 103-fold higher
affinity for CB1R and CB2R, respectively, than (-)-CBD, a 316-fold and a
50-fold increased affinity compared to (+)-CBD, and a 180-fold and
82-fold increased affinity compared to (-)-CBD-HPE (Table 1). Thus, we
selected (+)-CBE-HPE to evaluate the functional activity on CB1R and
CB2R signaling by luciferase assay in 293 T-CB1-CRE-Luc and
293 T-CB2-CRE-Luc cell lines. As depicted in Fig. 2A, (+)-CBE-HPE
showed CB2R agonistic activity starting at 100 nM (Fig. 2A), while it did
not activate CB1R at the concentrations tested (Fig. 2B). (+)-CBE-HPE
showed a strong CB1R antagonistic activity against WIN 55,212–2
compound, starting at 100 nM and with a full inactivation at 5 µM
(Fig. 2C). The concentration-response curves showed values of IC50 for
CB1R and EC50 for CB2R of 0.21 ± 0.07 and 0.09 ± 0.78
μmol/L,
respectively.
3.2. (+)-CBD-HPE prevents STZ-induced hyperglycemia
Phyto- and synthetic cannabinoids have been shown to delay the
onset of diabetes and alleviate inflammation in metabolic-related dis-
eases; CB1R has been proposed as a target for the treatment of metabolic
disorders and antifibrotic treatments, and both CB1R and CB2R targets
for the treatment for inflammation. Thus, we tested (+)-CBD-HPE in an
experimental mouse model of T1D. Eight- to 10-week-old C57BL6J mice
were pretreated with vehicle or 10 mg/kg of (+)-CBD-HPE for one-
week, prior insult with STZ, a drug preferentially toxic to pancreatic
beta cells, or citrate buffer (healthy control) (Fig. 3 A). Vehicle-STZ mice
developed hyperglycemia 3 days after STZ injection (Fig. 3B). Mice
treated with (+)-CBD-HPE did not become hyperglycemic, and blood
glucose levels were significantly lower than those of vehicle-STZ mice
and comparable to healthy control mice (Fig. 3B). On day 14, fasting
blood glucose was significantly higher in vehicle-treated mice than
healthy controls (114 ± 8 mg/dl vs. 89 ± 4 mg/dl, respectively). Mice
pretreated with (+)-CBD-HPE had significantly lower fasting blood
glucose (81 ± 5 mg/dl), comparable to healthy control. Vehicle-STZ
mice were glucose intolerant as shown by higher blood glucose levels
than healthy controls during an IPGTT (Fig. 3D-E). Pretreatment with
(+)-CBD-HPE improved glucose tolerance in STZ-injected mice, as
shown by lower blood glucose than vehicle-STZ mice during an IPGTT
(Fig. 3D-E).
3.3. (+)-CBD-HPE alleviates STZ-induced pancreatic beta cell loss
STZ induces T1D by directly impacting insulin-producing beta cells,
leading to loss of beta cell mass, hence hyperglycemia. Since (+)-CBD-
HPE prevented STZ-induced hyperglycemia, we investigated the effect
of (+)-CBD-HPE on beta cells. As described previously, STZ induced a
significant 2.8-fold reduction of islet insulin content, as determined by
insulin staining of the pancreas (Fig. 3F-G), and a loss of 78% of beta cell
mass compared to healthy controls (Fig. 3H), accompanied by a signif-
icant 1.5-fold increase in islet area (Fig. 3I). Islets from mice pretreated
with (+)-CBD-HPE had significantly more intra-islet insulin content
than those from vehicle-STZ mice, and only a 1.6-fold reduction
compared to healthy control (Fig. 3F-G). Importantly, (+)-CBD-HPE
prevented STZ-induced beta cell mass loss (Fig. 3H). Islet area was
significantly increased by 1.2-fold in (+)-CBD-HPE pretreated STZ-mice
compared to healthy control (Fig. 3I).
Fig. 2. Pharmacological evaluation of (+)-CBD-HPE. (a) hCB2R receptor ago-
nism. HEK-293T-CB2-CRE-Luc cells were treated with WIN 55,212–2 (WIN) or
(+)-CBD-HPE for 30 min and stimulated with FSK for 6 h. Then, cells were
lysed for luciferase activity. Data are shown as mean activation percentage ± S.
D. considering FSK as 100% activation. (n = 3). ***p < 0.001 versus FSK. (b)
hCB1R receptor agonism. HEK-293T-CB1-CRE-Luc cells. were treated with WIN
55,212–2 (WIN) or (+)-CBD-HPE for 6 h and lysed for luciferase activity
measurement. (c) hCB1R receptor antagonism. Results of CB1-CRELuc-HEK-293
cells pretreated with (+)-CBD-HPE and stimulated with WIN 55,212–2 for six
hours. The effect of WIN 55,212–2 was considered a 100% activation. Results
are shown as mean ± SD (n = 3). **p < 0.01 and ***p < 0.001 versus
WIN 55,212–2.
from vehicle-STZ mice showed activation of NF-κB, determined by a
30% increase in its phosphorylation and nuclear localization compared
to healthy control (Fig. 4A-B), which was prevented by (+)-CBD-HPE
(Fig. 4A-B). Treatment with STZ triggered the infiltration of T cells into
the islet, a process known as insulitis, as determined by a significant
increase in the number of CD3 + cells (Fig. 4C-D). (+)-CBD-HPE
3.4. (+)-CBD-HPE prevents STZ-induced inflammation
Damage in beta cells by STZ triggers islet inflammation [19], and
beta cell mass loss is driven by activation of NF-κB in T1D [20]. Islets
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Pharmacological Research 169 (2021) 105492
Fig. 3. (+)-CBD-HPE prevents STZ-induced hyperglycemia and protects beta cell mass. (a) Mice were treated with vehicle-citrate buffer (Vehicle-Cit. Bf.; black
circles, solid line; black bars), vehicle-STZ (red triangles, red line; red bars), or 10 mg/kg of (+)-CBD-HPE-STZ (white squares, dotted line; white bars). (b) Non-
fasting blood glucose (BG) was monitored daily and (c) fasting blood glucose after 6 days of treatment. IPGTT was performed after 6 days of treatment, (d)
blood glucose measured, and (e) area under the curve calculated. N = 6–7 mice/group. (f) Representative photomicrographs (20X) of insulin (green) and nuclei
(DAPI, blue) staining of the pancreas. The scale bar is 50 µm. Quantification of (g) intra-islet staining, (h) beta cell mass per islet, and (i) average islet area. N = 100
islets/group, N = 6 mice/group for Vehicle-Cit. Bf. and (+)-CBD-HPE-STZ groups and N = 7 mice/group for Vehicle-STZ. Results are mean ± SEM. Significance when
*p < 0.05, **p < 0.01 and ***p < 0.001 versus vehicle-citrate buffer-treated mice, #p < 0.05, ##p < 0.01 and ###p < 0.001 versus vehicle-STZ.
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Pharmacological Research 169 (2021) 105492
Fig. 4. (+)-CBD-HPE prevents STZ-induced beta cell apoptosis and ameliorates inflammation. Representative photomicrographs (20X), and quantification, of
pancreas immunostaining for (a-b) of p-NF-κB-DAB, (c-d) CD3 (red) and nuclei (DAPI, blue), and (e-f) cleaved caspase 3 (red), insulin (green), and nuclei (DAPI, blue)
in vehicle-citrate buffer- (Vehicle-Cit. Bf.; black bars), vehicle-STZ- (red bars) and (+)-CBD-HPE-STZ-treated mice (white bars) mice. The scale bar is 50 µm. N = 100
islets/group, N = 6 mice/group for Vehicle-Cit. Bf. and (+)-CBD-HPE-STZ groups and N = 7 mice/group for Vehicle-STZ. Quantification of plasma (g) IFN-γ, (h) IL-5,
(i) TNF-α and (j) IL-18 by ELISA. N = 6–7 mice/group. Results are mean ± SEM. Significance when *p < 0.05, **p < 0.01 and ***p < 0.001 versus vehicle-citrate
buffer-treated mice, #p < 0.05, ##p < 0.01 and ###p < 0.001 versus vehicle-STZ-treated mice.
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Pharmacological Research 169 (2021) 105492
prevented STZ-induced insulitis (Fig. 4C-D). STZ further induced beta
cell apoptosis, determined by a 2-fold increase in intra-islet cleaved
caspase 3 staining compared to healthy control (Fig. 4E-F). Treatment
with (+)-CBD-HPE completely avoided STZ-mediated beta cell death
(Fig. 4E-F). It has been previously described that cannabinoids can
regulate GLUT2, which is responsible for STZ toxicity [21,22]. We found
no significant differences between vehicle and (+)-CBD-HPE-treated
mice in GLUT2 levels in islets (Supplementary Fig. 2A-B).
Plasma levels of IFN-γ were undetectable in healthy control, and
treatment with STZ significantly increased their levels (Fig. 4G).
Fig. 5. (+)-CBD-HPE averts diabetic nephropathy. Representative photomicrographs (10X) of (a) glomerulus from vehicle-citrate buffer- (Vehicle-Cit. Bf.; black
bars), vehicle-STZ- (red bars) and (+)-CBD-HPE-STZ-treated mice (white bars) kidney stained with PAS. Quantification of glomerulus (b) diameter, (c) area, and (d)
glomerular lesion score. (e) Representative photomicrographs (10X) and quantification of (f) tubular and (g) interstitial lesion score from vehicle-citrate buffer-
(Vehicle-Cit. Bf.; black bars), vehicle-STZ- (red bars) and (+)-CBD-HPE-STZ-treated mouse (white bars) kidneys stained with PAS. The scale bar is 50 µm. N = 20
images/group, N = 6 mice/group for Vehicle-Cit. Bf. and (+)-CBD-HPE-STZ groups and N = 7 mice/group for Vehicle-STZ. Results are mean ± SEM. Significance
when *p < 0.05, **p < 0.01 and ***p < 0.001 versus vehicle-citrate buffer, #p < 0.05, ##p < 0.01 and ###p < 0.001 versus vehicle-STZ.
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Treatment with (+)-CBD-HPE significantly reduced the levels of IFN-γ of
2.5 folds compared to STZ-treated mice (Fig. 4G). Treatment with
(+)-CBD-HPE also significantly increased IL-5 levels of 3 folds compared
to STZ-treated mice (Fig. 4H), suggesting a protective anti-inflammatory
dilatation, of 2.9 folds compared to healthy control (Fig. 5A, D).
Treatment with (+)-CBD-HPE prevented the glomerular hypertrophy
induced by STZ, as observed by a glomerular area and diameter com-
parable to healthy controls (Fig. 5A-C), and tended to, although it was
not significantly (p = 0.09), reduce the glomerular lesions (Fig. 5A, D).
STZ also induced significant degeneration and atrophy of tubules, with a
3.9-fold increase in tubular lesion score compared to healthy control
(Fig. 5E-F). (+)-CBD-HPE prevented STZ-induced tubular lesions
(Fig. 5E-F). STZ increased the interstitial lesion score, i.e. an increase in
interstitial fibrosis and inflammation, of 6.8 folds compared to healthy
controls (Fig. 5E, D), while treatment with (+)-CBD-HPE induced a
significant 1.95-fold reduction of these lesions (Fig. 5E, D). As described
previously [22], STZ induced a significant increase in GLUT2 levels in
the kidney (Supplementary Fig. 2B-C). Treatment with (+)-CBD-HPE
had no significant effect on renal GLUT2 levels (p = 0.2; supplementary
Fig. 2B-C).
role against STZ damage. Levels of TNFα tended to increase only upon
STZ treatment compared to healthy controls (p = 0.07) (Fig. 4I). Plasma
levels of IL-18 were significantly higher in both STZ- and (+)-CBD-HPE-
treated mice compared to healthy controls (Fig. 4J), suggesting that the
protective role of (+)-CBD-HPE occurs by T cell rather than macrophage
modulation.
3.5. (+)-CBD-HPE prevents STZ-induced renal injury
Previous studies demonstrate that targeting the cannabinoid re-
ceptors alleviates renal injury [12,23,24]. We assayed kidney samples
histologically by PAS staining to determine morphological changes in
the glomerulus, tubules, and interstitium of diabetic mice compared to
healthy controls. STZ induced glomerular morphological changes, as
reflected by an increase in glomerulus diameter and area (Fig. 5A-C).
STZ also significantly increased the glomerular lesion score, i.e.
increased in hypercellularity, mesangial matrix lesions, and capillary
3.6. (+)-CBD-HPE prevents STZ-induced renal fibrosis and inflammation
In diabetic nephropathy, the overproduction of extracellular matrix
is a feature of the disease that leads to inflammation and glomerular
Fig. 6. (+)-CBD-HPE prevents fibrosis and inflammation in the kidney. Representative photomicrographs (10X), and quantification, of kidney stained for (a-b) PSR
and (c-d) CD3-DAB from vehicle-citrate buffer- (Vehicle-Cit. Bf.; black bars), vehicle-STZ- (red bars) and (+)-CBD-HPE-STZ-treated mice (white bars). The scale bar is
50 µm. N = 20 images/group, N = 6 mice/group for Vehicle-Cit. Bf. and (+)-CBD-HPE-STZ groups and N = 7 mice/group for Vehicle-STZ. Quantification of (e)
plasma creatinine and (f) BUN. N = 6 mice/group for Vehicle-Cit. Bf. and (+)-CBD-HPE-STZ groups and N = 7 mice/group for Vehicle-STZ. Results are mean ± SEM.
Significance when **p < 0.01 and ***p < 0.001 versus vehicle-citrate buffer, #p < 0.05, ##p < 0.01 and ###p < 0.001 versus vehicle-STZ.
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Pharmacological Research 169 (2021) 105492
sclerosis [25]. We determined renal fibrosis by PSR. PSR staining
showed that STZ treatment led to a 1.4-fold increase of the fibrosis in
glomeruli and interstitium compared to healthy controls (Fig. 6A-B).
Treatment with (+)-CBD-HPE fully prevented STZ-induced renal fibrosis
as observed by a significant reduction of PSR stained area compared to
STZ-vehicle (Fig. 6A-B). Diabetic nephropathy was associated with
recruitment and retention of lymphocytes, as shown by a significant
increase of 3.1-fold in the CD3+ stained area in the renal interstitium of
STZ-vehicle compared to healthy controls (Fig. 6C-D). Treatment with
(+)-CBD-HPE fully prevented the recruitment and/or retention of T
lymphocytes as observed by CD3 staining (Fig. 6C-D).
4S-menthadienol starting material with up to 5% (-)-CBD. This is due to
the (+)-CBDs crystalline characteristic, which enables the here discussed
purification by crystallization to isolate (+)-CBD with an enantiomeric
excess of 99% from a mixture of (-)- and (+)-CBD. Hence, we obtained a
compound highly-pure and with a pharmaceutical profile for cannabi-
noid receptors that made it highly interesting for its therapeutic
application.
The CB1R plays a key role in type 2 diabetic nephropathy. Indeed,
CB1R is overactive in this pathology [12], and its deletion in podocytes
prevents diabetic nephropathy in obesity [23]. Here we show that
(+)-CBD-HPE is a strong CB1R antagonist, and it is plausible that its
positive effect on the kidney depends on the antagonism of this receptor.
Previously it has been shown that pharmacological blockers of CB1R
were promising therapeutics for diabetic nephropathy [29,30]. CB1R,
located in the proximal tubule, when overactivated as it occurs in
obesity, plays a key role in the activation of inflammation and the
development of renal fibrosis [30]. Blockade of CB1R was able to prevent
chronic inflammation and also to significantly reduce renal fibrosis,
preserving kidney function. In T1D, similarly to type 2, hyperglycemia
causes hypertension, oxidative stress, and inflammation that chronically
leads to renal damage, and blockade of the CB1R seems to be thera-
peutic. Specifically, CB1R was described to regulate GLUT2 recirculation
in the kidney of T1D rodents, thus impacting on glucose absorbance and
renal injury and dysfunction [22]. However, treatment with
(+)-CBD-HPE was not able to restore the levels of GLUT2, suggesting
that (+)-CBD-HPE is reducing inflammation and fibrosis without
altering glucose transportation. We also show that (+)-CBD-HPE acts,
dually, as an agonist of the CB2R, a cannabinoid receptor that plays an
important role in immune cell regulation. Other dual-acting drugs have
been shown to effectively prevent nephropathy in rodents. A double
CB1R antagonist and iNOS agonist prevented inflammation, fibrosis,
oxidative stress, and thus renal damage in obese mice [30]. Here we
show that a novel dual-acting drug, that blocks CB1R and simultaneously
activates CB2R efficiently avert T1D and its associated renal complica-
tions. The action of (+)-CBD-HPE on CB2R can also, by itself, signifi-
cantly reduce the inflammation that eventually leads to tissue fibrosis. In
fact, another CB2R agonist, LEI-101, prevented cisplatin-mediated kid-
ney damage and dysfunction by reducing both oxidative stress and
inflammation within the tissue [31]. A more recent study showed that
activation of CB2R enhances renal vascularization thus enhancing renal
perfusion in a CB1R-independent manner [32]. However, a CB2R inverse
agonist, XL-001, has also been shown to prevent fibrogenesis, and CB2R
knockout mice are protected against renal fibrosis [33], contrary to the
findings of Dr. Mukhopadhyay et al. Despite these discrepancies, that
can be explained by the differences in the models of study, drug-toxicity
based vs unilateral ureteral obstruction, our findings show that a dual
acting CB1R antagonist and CB2R agonist is able to prevent renal
inflammation and fibrosis in a mouse model of T1D, and that the benefit
includes lower inflammation, thus less morphological changes and
fibrosis, leading to preservation of kidney function.
Mice injected with STZ-vehicle, but not (+)-CBD-HPE-treated mice,
presented a significantly increased level of creatinine in plasma
compared to healthy controls (Fig. 6E). Also, treatment with STZ
induced a significant increase in BUN compared to healthy controls
(Fig. 6F), which was voided with (+)-CBD-HPE treatment (Fig. 6G).
4. Discussion
The phytocannabinoid (-)-trans CBD is a multitarget compound with
different biomedical applications. Besides, (-)-CBD has been used as a
template to develop novel chemical entities such as the aminoquinones
VCE-004.3 and VCE-004.8 [26,27], and the later has been formulated as
EHP-101 for oral delivery and a Phase II study in Systemic Sclerosis
patients has been initiated (ClinicalTrials.gov: NCT04166552). In
contrast, the synthetic enantiomer (+)-trans-CBD has been poorly
explored. Herein, we confirmed that (+)-trans-CBD showed strong
binding to CB2R, and an enhanced affinity to CB1R compared to
(-)-trans-CBD. A further modification on position 2 of the resorcinol
moiety led to (+)-CBD-HPE that showed a very potent binding activity
on both CB1R and CB2R acting as a functional CB1R antagonist and CB2R
agonist. A molecule with these characteristics is of pharmacological
therapeutic interest considering the impact that targeting both receptors
has in a plethora of metabolic and immune disorders. We have
demonstrated (see [8] and present data) that (+)-enantiomers of CBD
and derivatives exhibit a strong elevation of their affinities and intrinsic
activities at both cannabinoid receptors, showing their potential as new
experimental tools for research and, even, for therapeutic development,
a fact investigated in the second part of this study. A potential trans-
formation of (+)-enantiomers in the (-)-forms by intracellular racemases
and vice-versa may represent an important follow-up objective to be
investigated, given that it may enhance or reduce their biological effects.
This is something relevant to be investigated, but it is unlikely that it
happened in our binding analysis conducted with commercial mem-
branes, since there is only the receptor of interest. By contrast, racemi-
zation might happen in our cell-based and in vivo assays, but, in that
case, the result would be a reduction in the biological effect of the
(+)-CBD-HPE, which was not found in our study.
The synthesis of (+)-CBD and (+)-CBD-HPE is similar to the widely
known synthetic route for preparations of the natural occurring (-)-CBD
[28]. Olivetol methyl ester and the respective terpene (4S-menthadie-
noles for (+)-CBD derivatives) undergo a Friedel Craft alkylation to the
respective Cannabidiol carboxylic methyl ester. The respective ester is
subsequently saponified to the crystalline (+)-CBD. (+)-CBD-HPE could
be prepared by transesterification of the (+)-CBD methyl ester with the
appropriate alcohol. This transesterification can be done with the ma-
jority of known organic alcohols, which opens up a near-infinite number
of future new (+)-CBD derivatives with novel pharmaceutical
applications.
Damage induced by STZ in the pancreas includes oxidative stress and
activation of the inflammatory response, leading to apoptosis of beta
cells. Eventual beta cell mass loss because of STZ causes loss of circu-
lating insulin, hence hyperglycemia. CBD has been shown to delay the
onset of T1D in non-obese diabetic mice, although the mechanism of this
observation is unknown. We found that (+)-CBD-HPE ameliorated beta
cell mass loss because of STZ by greatly reducing islet inflammation and
T cells infiltration into the islets. Moreover, (+)-CBD-HPE prevented
STZ-induced beta cell apoptosis. The blockade of CB1R has been shown
to enhance beta cell function [21,34,35]. In another model of metabolic
disorder, genetic ablation of CB1R in beta cells (i.e. “blockade” of CB1R)
leads to an inhibition of the inflammasome in islets, preventing the
activation of NF-κB and, consequently, voiding immune cells infiltration
in and around the islets [14]. Hence, blockade of CB1R is a therapeutic
approach to preserve beta cell mass and function. In fact, CB1R, by
directly binding to the insulin receptor in beta cells, modulates its
Contrary to the synthesis of naturally occurring (-)-CBD, there is a
problem of enantiomeric purity. 4R-menthadienols or their precursors
(e.g. (-)-limonene) are not readily naturally available in enantiomeric
pure compositions or have to be prepared with an increased technical
effort. This necessitates, for compounds like (+)-CBD-HPE, either
enantiomeric pure starting materials or an expensive and time-
consuming chiral purification method. (+)-CBD however tolerates a
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Pharmacological Research 169 (2021) 105492
downstream signal, acting, when overactivated, as an inducer of beta
cell apoptosis through the Akt pathway [36]. Thus, (+)-CBD-HPE may
be preserving beta cells by blocking CB1R, reducing both beta cell
inflammation and apoptosis. Moreover, defects on CB2R signaling leads
to incapability to suppress T cell proliferation, increasing the risk of
immune-related disorders (reviewed in [37]). Of note, (+)-CBD-HPE
partially supported by grants SAF2017-87701-R to EM from the Ministry
of the Economy and Competition, Spain (MINECO) co-financed with the
European Union FEDER funds, and RTI2018-098885-B-100 to JFR from
the Ministry of Science, Innovation and University, Spain (MICIU).
˜
Emerald Health Biotechnology Espana SLU and Symrise AG also sup-
ported this work and had no further role in study design, the collection,
analysis, and interpretation of data, in the writing of the report, or in the
decision to submit the paper for publication.
reduced the pro-inflammatory cytokines IFN-γ and TNFα, while
increasing the IL-5, indicating that it may be acting as an
anti-inflammatory compound at the T cell level by altering the Th1/Th2
ratio. The phytocannabinoid THC significantly reduces Th1 cytokine
production while enhancing the production of cytokines characteristic
of Th2 cells in human leukocytes, in a CB2R-dependent manner [38]. In
line with these observations, a dual CB1R-antagonist CB2R agonist such
as (+)-CBD-HPE is a good candidate for the treatment of T1D to preserve
beta cell mass and protect from islet inflammation and insulitis. It is also
important to emphasize that this protection of the pancreatic beta cells
and prevention of the inflammatory damage induced by STZ could also
be behind the nephroprotective mechanism of renal protection. How-
ever, previous studies showed that targeting of CB1R and CB2R in dia-
betic mice is a promising strategy for the treatment of diabetic
nephropathy. When given in combination, the CB1R antagonist AM6545
and the CB2R agonist AM1241 to STZ-induced diabetic mice, they exert
a synergic effect on renal protection [39]. Further in vitro studies, as well
as in vivo studies in already diabetic mice are warranted to further
investigate the nephroprotective capacity of (+)-CBD-HPE. In addition,
the potential effect of both (+)-CBD and (+)-CBD-HPE on other (-)-CBD
targets such as GPR55, Adenosine receptors, 5-HT1A, 5-HT2A or PPARγ
need to investigated for a further characterization of these compounds.
Various pharmacological strategies to safely target the cannabinoid
receptors have been taking place since the 2000’s after the Rimonabant
fiasco despite its multiple beneficial effects due to its action on the
central nervous system [40]. In this sense, peripherally-acting as well as
more specific drugs have been developed [41]. Recently, dual-acting
drugs have been suggested and proven to be a strong approach to add
another level of specificity and safety [42]. However, due to the dark
past of CB1R blockade, tissue distribution and behavioral studies will be
necessary for the translational value of (+)-CBD-HPE.
Conflict of Interest
BCH and JDUB are employees of Emerald Health Biotechnology, MW
is an employee of Symrise AG and submitted a PCT (PCT/EP2018/
067366) describing the synthesis of (+)-CBD and (+)-CBD-HPE. EM is a
member of the Scientific Advisory Board of Emerald Health. Other au-
thors declare no conflicts of interest.
Appendix A. Supporting information
Supplementary data associated with this article can be found in the
online version at doi:10.1016/j.phrs.2021.105492.
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