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1
Introduction
β- caryophyllene (BCP) is a plant compound, a member
of bicyclic sesquiterpene. In nature, it mainly occurs as
trans- caryophyllene ((E)- BCP) mixed with small amounts
of its isomers, (Z)- β-caryophyllene (iso- caryophyllene) and
α- humulene (α- caryophyllene), as well as its oxidation
derivative—β- caryophyllene oxide (BCPO) (Fig. 1). In this
review, we will focus on two sesquiterpenes, BCP (in the
scientific literature, BCP mainly stands for (E)- BCP or
the natural mixture of BCP isomers) and BCPO.
BCP and BCPO have strong wooden odor and they
are used as cosmetic and food additives. These two natural
substances are approved as flavorings by the Food and
Drug Administration (FDA) and by the European Food
Safety Authority (EFSA) with identification number FL
no: 01.007 for BCP and FL no: 16.043 for BCPO. Both
compounds exhibit low water solubility, thereby the aque-
ous medium such as biological fluids, impede their absorp-
tion to the cell. However, it was shown that both BCP
and BCPO are able to interact with artificial lipid bilayer,
which strongly suggests their high affinity to the cell
RE VIE W
β- caryophyllene and β- caryophyllene oxide—natural
compounds of anticancer and analgesic properties
Klaudyna Fidyt1,2, Anna Fiedorowicz1, Leon Strza˛dała1 & Antoni Szumny2
1Laboratory of Tumor Molecular Immunobiology, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences,
12 Rudolf Weigl, Wroclaw 53-114, Poland
2The Faculty of Food Science, Department of Chemistry, Wrocław University of Environmental and Life Sciences, 25/27 C.K. Norwida, Wroclaw
50-375, Poland
© 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use,
distribution and reproduction in any medium, provided the original work is properly cited.
Keywords
Analgesic, anticancer, antinociception,
cannabinoid receptor type 2 (CB2), β-
caryophyllene (BCP), β-caryophyllene oxide
(BCPO)
Correspondence
Anna Fiedorowicz, Laboratory of Tumor
Molecular Immunobiology, Ludwik Hirszfeld
Institute of Immunology and Experimental
Therapy, Polish Academy of Sciences, 12
Rudolf Weigl, 53-114 Wroclaw, Poland.
Tel: +48-71 3709939; Fax: +48-71-337 2171;
E-mail: anna.fiedorowicz@iitd.pan.wroc.pl
Funding Information
This work was supported by the grant 3/2016
from the State Committee for Scientific
Research, Warsaw, Poland and the Wroclaw
Centre of Biotechnology, program “The
Leading National Research Centre (KNOW)
for years 2014–2018.”
Received: 14 March 2016; Revised: 21 May
2016; Accepted: 10 June 2016
doi: 10.1002/cam4.816
Abstract
Natural bicyclic sesquiterpenes, β- caryophyllene (BCP) and β- caryophyllene oxide
(BCPO), are present in a large number of plants worldwide. Both BCP and
BCPO (BCP(O)) possess significant anticancer activities, affecting growth and
proliferation of numerous cancer cells. Nevertheless, their antineoplastic effects
have hardly been investigated in vivo. In addition, both compounds potentiate
the classical drug efficacy by augmenting their concentrations inside the cells.
The mechanisms underlying the anticancer activities of these sesquiterpenes are
poorly described. BCP is a phytocannabinoid with strong affinity to cannabinoid
receptor type 2 (CB2), but not cannabinoid receptor type 1 (CB1). In opposite,
BCP oxidation derivative, BCPO, does not exhibit CB1/2 binding, thus the
mechanism of its action is not related to endocannabinoid system (ECS) ma-
chinery. It is known that BCPO alters several key pathways for cancer develop-
ment, such as mitogen- activated protein kinase (MAPK), PI3K/AKT/mTOR/
S6K1 and STAT3 pathways. In addition, treatment with this compound reduces
the expression of procancer genes/proteins, while increases the levels of those
with proapoptotic properties. The selective activation of CB2 may be considered
a novel strategy in pain treatment, devoid of psychoactive side effects associated
with CB1 stimulation. Thus, BCP as selective CB2 activator may be taken into
account as potential natural analgesic drug. Moreover, due to the fact that
chronic pain is often an element of cancer disease, the double activity of BCP,
anticancer and analgesic, as well as its beneficial influence on the efficacy of
classical chemotherapeutics, is particularly valuable in oncology. This review is
focused on anticancer and analgesic activities of BCP and BCPO, the mecha-
nisms of their actions, and potential therapeutic utility.
Cancer
Medicine Open Access
2© 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.
K. Fidyt et al.
Sesquiterpenes in Cancer and Analgesia
membrane [1]. The potential obstacles associated with
poor solubility of these sesquiterpenes in aqueous fluids
may be overcome through usage of liposomal drug delivery
system, which provides much higher bioavailability of these
compounds and by that ensures obtaining desired biologi-
cal effects.
BCP is one of the major active component of essential
oils derived from large number of spice and food plants.
According to Essential Oil Database (EssOilDB) (http://
nipgr.res.in/Essoildb/), BCP as a plant volatile compound
is commonly found in basil (Ocimum spp.), cinnamon
(Cinnamomum spp.), black pepper (Piper nigrum L.),
cloves (Syzygium aromaticum), cannabis (Cannabis sativa
L.), lavender (Lavandula angustifolia), oregano (Origanum
vulgare L.), and rosemary (Rosmarinus officinalis). Its
biological effects include anti- inflammatory [2], anticar-
cinogenic [3], antimicrobial [4], antioxidative [5], and
analgesic activities [6].
Similarly to BCP, BCPO due to its high biological activ-
ity was extensively studied in recent years. EssOilDB- based
data indicate basil (Ocimum spp.), salvia (Salvia glutinosa)
and Syzygium cordatum as the main natural sources of
BCPO. Either as a pure substance or a component of
plant essential oils, BCPO was found to exhibit anti-
inflammatory [7], antioxidant, antiviral [8], anticarcino-
genic [9], and analgesic properties [10].
The metabolism of BCP(O) is poorly described. While
BCP metabolic pathway was investigated in rabbits, there
is some information on BCPO biotransformation. In vivo
tests performed on rabbits revealed that (E)- BCP is con-
verted to intermediate metabolite, (–)- caryophyllene- 5,
6- oxide, which is metabolized to [10S- (−)- 14- hydroxycaryophyllene-
5,6- oxide] or hydroxylated to by- product, caryophyllene-
5,6- oxide- 2,12- diol (Fig. 2) [11]. By comparison with rabbit
metabolic pathway, one can suspect that BCP may undergo
sequential transformations also in humans, however the
experimental data confirming this hypothesis is lacking
[11]. Interestingly, Hart and Wong [12] evaluated BCP
toxicity in rats and found that oral lethal dose (LD50)
for this compound was higher than 5000 mg/kg.
BCP belongs to a class of cannabinoids (CBs), specifi-
cally phytocannabinoids (pCBs), which were identified as
plant derivatives of Cannabis sativa L. Natural and synthetic
cannabinoids have ability to activate the cannabinoid
receptors (CB1 and CB2), however BCP, which is com-
mon in essential oil from C. sativa (up to 37%) [13],
activates exclusively CB2 and exhibits no affinity to CB1.
This implies that BPC action is devoid of psychoactive
side effects associated with CB1 activation and suggests
its potential use in medicine. The quantitative radioligand-
binding experiments showed that E- BCP displays insensibly
higher biding affinity to CB2 than its isomer Z- BCP,
whereas BCPO and α- humulene possess no CB2 binding
properties. In addition, all these compounds did not bind
to CB1 [14]. Lack of affinity of BCPO to CB2 clearly
shows that both chemically related compounds, BPC and
BCPO, exert their biological activities though at least
partially different mechanisms.
Cannabinoid Receptors
Cannabinoid receptors—cannabinoid receptor type 1 (CB1)
and type 2 (CB2)—are G- protein- coupled receptors
(GPCR) and main components of endocannabinoid system
(ECS). They play important roles not only in the main-
tenance of energy balance, metabolism, neurotransmission,
and immune response, but are also engaged in pathological
processes, for example, neuropathic pain [15–17]. CB1
and CB2 differ essentially in their structures, ligands, cel-
lular distributions, and topologies. CB1 are mostly localized
to the central nervous system (CNS), whereas CB2 are
found predominantly in the peripheral tissues and immune
cells. However, immunohistochemical studies revealed that
CB2 are also expressed in the brain, glial cells, and neu-
rons [18, 19]. Both types of CB receptors are elements
of numerous signaling pathways, mediating cellular
Figure 1. Trans- caryophyllene, its isomers, and oxidative product.
3
© 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.
Sesquiterpenes in Cancer and Analgesia
K. Fidyt et al.
responses to various bioactive molecules such as hormones,
local mediators, or neurotransmitters. For that reason,
they are also involved in pathomechanisms of many clini-
cal conditions such as obesity, osteoporosis, neurodegen-
erative/neuroinflammatory disorders, psychiatric diseases,
stroke, and spinal cord injury [20–22].
BCP binding to CB2 results in the activation of Gαi/o
protein, which leads to decline of cAMP production and
in consequence inhibition of adenylyl cyclase. In addition,
ligand- coupled CB2 activate Gγβ proteins and stimulate
both mitogen- activated protein kinase (MAPK) and phos-
phoinositide 3- kinase (PI3K) signaling pathways [23].
Moreover, the chemical modifications of BCP have impact
on its activity through generating molecules with different
affinities to CB1/2, thus altered pharmacological traits [24].
BCP(O) as Anticancer Agents
Many investigations have been made to establish the
potential utility of cannabinoids in cancer therapies.
Currently, it is believed that all anticancer activities of
cannabinoids may be based on three different mechanisms
such as (1) induction of apoptosis [25], (2) repression
of cell cycle [26], and (3) inhibition of angiogenesis and
metastasis [27]. The anticancer properties of BCP and
BCPO are less recognized than those of traditional can-
nabinoids, however several lines of evidence have dem-
onstrated that these natural compounds can be interesting
candidates for complementary treatment of the cancer.
Both sesquiterpenes revealed cytotoxic activities against
several types of cancer cells. It was shown that BCPO
isolated from Jeju guava (Psidium cattleianum Sabine)
leaves exerted cytotoxic effect on various cancer cell lines,
such as HeLa (human cervical adenocarcinoma cells),
HepG2 (human leukemia cancer cells), AGS (human lung
cancer cells), SNU- 1 (human gastric cancer cells), and
SNU- 16 (human stomach cancer cells). Interestingly, com-
parative data analysis has shown that dose of BCPO and
time required for BCPO- induced cytotoxicity was specific
for each studied cell line [28]. Moreover, Shahwar et al.
[29] noted that BCPO derived from Cinnamomum tamala
leaf extracts exhibited moderate cytotoxic activity against
Figure 2. The metabolism of (E)- BCP in rabbits. Based on Asakawa et al. (1986). BCP, β- caryophyllene.
4© 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.
K. Fidyt et al.
Sesquiterpenes in Cancer and Analgesia
human ovarian cancer cell line, A- 2780. The antiprolifera-
tive effect of BCP on several cancer cell lines was reported
by Dahham et al. [30]. They found that treatment with
BCP obtained from essential oils of Aquilaria crassna stem
bark led to strong growth inhibition in two colon cancer
cell lines, HCT- 116 and HT- 29, as well as in pancreatic
cancer cells, PANC- 1, whereas other tested cancer cell
lines demonstrated moderate susceptibility to BCP. In
contrast, Ambrož et al. [31] studies revealed that BCP
isolated from Myrica rubra did not affect CaCo- 2 intestinal
cancer cell viability at used doses. On the other hand,
BCP isomer, α- humulene, exhibited significant antipro-
liferative activities against those cells. Moreover, the cyto-
toxic effect of not only α- humulene, but also
iso- caryophyllene, was enhanced by BCP. Furthermore,
both isomers combined with BCP were more effective in
reduction of MCF- 7 human breast cancer cell line pro-
liferation than when used separately [32]. Amiel et al.
[33] demonstrated that treatment of BS- 24- 1 (mouse
lymphoma cell line—T cells) and MoFir (human B lym-
phocytes transformed with Epstein–Barr virus) cells with
BCP- activated caspase- 3 and led to internucleosomal frag-
mentation of DNA, one of the main features of apoptosis.
Analogous changes were observed by Dahham et al. [30]
in HCT- 116 cells treated with BCP derived from the
essential oil of A. crassna. Interestingly, Amiel et al. [33]
showed that human skin fibroblast (FB) were resistant
to Commiphora gileadensis stem extracts, in which BCP
was a major compound.
Despite many reports on antiproliferative and cytotoxic
properties of BCP(O) toward numerous cancer cell lines,
there is only limited data supporting the antitumor efficacy
of these compounds in animal models. Jung et al. [34]
described in their excellent work the effects of BCP treat-
ment on the multiple cancer parameters in obese mice.
Authors observed that animals fed the high- fat diet (HFD)
and injected with B16F10 melanoma cells were prone to
form larger and more aggressive tumors than their lean
counterparts, and BCP treatment abolished the HFD pro-
cancer effects. The anticancer activity of BCP in vivo was
also presented at the Euro Global Summit on Cancer
Therapy in Valencia, 2015 [35]. In this report, a growth
and vascularization of tumors developed from orthotopi-
cally grafted colon cancer cells into nude mice were reduced
significantly after administration of BCP isolated from
agar wood. Interestingly, Campos et al. [36] demonstrated
an additional bioactivity of BCP, which could be useful
in cancer therapy. Thus, they found that BCP treatment
alleviated the leukopenia induced by the experimental
chemotherapy in rats. Taking into account the strong
evidence of BCP(O) antineoplastic actions in vitro, there
is an urgent need to test these compounds in animal
model systems. This is particularly important since up to
now only one peer- reviewed report describing an in vivo
effect of BCP on tumor growth exists in the scientific
literature. Moreover, there is some information on BCPO
antitumor activity in animal models.
Aside from the direct anticancer activities, BCP and
BCPO have ability to enhance the efficacy of classical
anticancer drugs, such as paclitaxel or doxorubicin (DOX)
[31, 32, 37]. Ambrož et al. [31] have reported that BCPO
potentiated the anticancer activities of DOX toward CaCo- 2
cells. Authors noted that cotreatment with BCPO increased
the concentration of DOX in CaCo- 2 cells in dose-
dependent manner leading ultimately to accumulation of
the drug in the cells. Likewise, BCPO was shown to
improve the anticancer effectiveness of paclitaxel [37],
which is a microtubule toxin with ability to arrest cells
in mitosis by interfering with normal breakdown of micro-
tubules during cell division [38]. Kim et al. [37] found
a potentiating influence of BCPO on DOX and paclitaxel
anticancer activities in human myeloid leukemia (KBM- 5),
multiple myeloma (U266), and human prostate cancer
(DU145) cell lines. Furthermore, Legault et Pichette [32]
showed that BCP can also increase the anticancer drug
efficacy. Thus, they observed the enhancement of paclitaxel
activity in MCF- 7 (breast cancer), DLD- 1 (colon cancer),
and L- 929 (murine fibroblast) cells cotreated with BCP.
Interestingly, in DLD- 1 cell line, BCP induced the accu-
mulation of paclitaxel inside the cells [32], thus exhibited
the analogs mechanism of action to that of BCPO. The
ability of BCP to increase the intracellular concentrations
of anticancer drugs may be linked to its chemical structure
of sesquiterpene. Namely, various cyclic hydrocarbons such
as terpenes may assemble in the cell membrane leading
to higher bilayer permeability [39]. Thus, it is likely that
BCP is incorporated into the membrane of cancer cell,
making it more available for entering the drugs.
The Mechanisms of BCP(O) Anticancer
Activities
Many experiments have been performed in order to elu-
cidate the mechanisms of anticancer activities of BCPO.
On the contrary, the mechanisms underlying the anti-
neoplastic actions of BCP have hardly been studied. It
seems that among these two compounds, BCPO possesses
stronger anticancer properties, which can be explained by
its chemical structure. Thus, BCPO contains methylene
and epoxide exocyclic functional groups, therefore it binds
covalently to proteins and DNA bases by sulfhydryl and
amino groups. For that reason, BCPO reveals high potential
for being signaling modulator in tumor cancer cells [40].
Anticancer activities of both sesquiterpenes may be exerted
through suppression of cellular growth and induction of
apoptosis. Park et al. [40] showed that BCPO suppressed
5
© 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.
Sesquiterpenes in Cancer and Analgesia
K. Fidyt et al.
PC- 3—prostate cancer cell and MCF- 7—breast cancer cell
proliferation in a dose- dependent manner. Moreover, it
induced ROS generation, MAPK activation, and inhibition
of PI3K/AKT/mTOR/S6K1 signaling pathway in these cells,
a pathway which is essential in cell survival, proliferation,
and angiogenesis of the tumor [41]. Furthermore, the
authors found that BCPO significantly reduced levels of
procancer proteins, those involved in proliferation—cyclin
D1, metastasis—COX- 2 (cyclooxygenase 2), angiogenesis—
VEGF (vascular endothelial growth factor), and apoptosis
inhibitors—bcl- 2 (B- cell lymphoma 2), bcl- xL (B- cell
lymphoma extra- large), IAP- 1, IAP- 2 (inhibitor of apop-
tosis 1 and 2), and survivin. In contrast, a treatment with
this natural compound augmented the expression of tumor
suppressors—p53 and p21—in PC- 3 cells [40]. Suppression
of AKT/mTOR/S6K1 signaling in PC- 3 cells was also
reported after treatment with hexane fraction obtained
from guava leaf (Psidium guajava L.), in which BCPO
was a major bioactive constituent [42]. BCPO also targets
STAT3 (Signal Transducer and Activator of Transcription
3) signaling pathway, which is involved in proliferation,
survival, invasion, angiogenesis, and metastasis of cancer
and was found to be highly active in many human tumors
[43]. Kim et al. [44] observed the reduced activity of
STAT- 3 transcription factor after BCPO treatment in
multiple melanoma, breast, and prostate cancer cell lines.
They reported that suppression of STAT3 pathway by
BCPO was mediated through activation of SHP- 1 protein
tyrosine phosphatase. Moreover, BCPO was capable to
block the IL- 6- induced activation of STAT- 3 and the
upstream elements of STAT3 pathway, such as c- Src, JAK1,
and JAK2, in time- and dose- dependent manners.
Proapoptotic activity of BCPO in cancer cells can be
associated with reduced activation of NF- κB [37]. NF- κB
is one of the key transcription factors in tumor develop-
ment, controlling such processes as cancer cell prolifera-
tion, tumorigenesis, angiogenesis, and metastasis [45].
NF- κB regulates expression of a large number of genes,
involved in cellular proliferation, apoptosis, and inflam-
mation (e.g., TRAF—TNF receptor- associated factor,
c- FLIP—cellular FLICE- like inhibitory protein, survivin,
various chemokines, and cytokines). Kim et al. [37] reported
BCPO- induced inhibition of the constitutive and inducible
NF- κB activities in cancer cells. Moreover, they found
that BCPO increased the TNFα- caused apoptosis by inhib-
iting the NF- κB activation. In addition, treatment with
BCPO led to lowering the levels of cyclin D1, COX- 2,
and c- Myc, which expression was upregulated by TNFα.
Sain et al. [46] evaluated an influence of BCP and BCPO
fractions from Aegle marmelos extract on IMR- 32 human
neuroblastoma and Jurkat cell lines. They found that
treatment of the cells with these chemical fractions led
to induction of p53- dependent apoptosis. Cellular death
was accompanied by upregulation of proapoptotic gene
expression, namely those encoding p53, bax, bak1, caspase
8, caspase 9, and ATM as well as decrement of mRNA
levels of antiapoptotic genes, such as bcl- 2, mdm2, COX-
2, and c- myb.
Taking together, BCP(O) present the anticancer activi-
ties toward numerous cancer cell lines, however strength
of the cellular response induced by treatment with these
compounds differs substantially among cancer cells. Doses
used in in vitro studies described in this review are listed
in Table 1. Moreover, the antitumor potential of BCP(O)
still needs to be evaluated in in vivo systems. Interestingly,
BCP(O) has ability to potentiate the efficacy of classical
drugs by augmenting their concentrations inside the cells.
The mechanisms underlying the antineoplastic effects
evoked by these sesquiterpenes are poorly recognized. One
can assume that BCP exerts its action through binding
to CB2. In contrast, BCPO does not display any affinity
to CB1/2, but reveals the equally strong (or ever stronger)
anticancer activity than BCP. It is known that BCPO alters
several key pathways for cancer development, such as
MAPK, PI3K/AKT/mTOR/S6K1, and STAT3 pathways. In
addition, treatment with this compound reduces the expres-
sion of procancer genes/proteins, while increases levels of
those with proapoptotic properties.
BCP(O) as Analgesic Agents
Pain is a subjective sensation, evoked by various internal
and external stimuli. In biological aspect, it is unpleasant
feeling, which arises from sensitization of nociceptors—
peripheral neurons responding to pain stimuli. Acute but
in particular chronic pain is a serious social burden, it
affects quality of life and leads to economic loss for patients
as well as health services [47]. It has been estimated that
around 10% of population worldwide suffers from long-
lasting pain [48].
One of the most difficult pain to manage is cancer
related. Many factors may be involved in etiology of cancer
pain, such as progression/invasion of the tumor, surgical
procedures and other cancer treatments, cancer- related
infections, etc. [49], which makes it complicated to treat.
As a consequence, a large part of oncological patients
tend to overuse the synthetic or semisynthetic pain killers
such as opioids or nonsteroidal anti- inflammatory drugs
(NSAIDs). Prolonged consumption of these medicines may
cause serious side effects leading to health complications
as well as drug tolerance and addiction. In order to decrease
a use of synthetic drugs, the natural products with strong
analgesic activities and low side effects are still being
sought. On account of that, cannabinoid receptors have
been extensively studied as mediators of analgesia and
thus potential targets for treatment of acute and
6© 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.
K. Fidyt et al.
Sesquiterpenes in Cancer and Analgesia
neuropathic pain [50]. Activation of those receptors by
endo- and exogenous ligands may inhibit pain responses,
therefore CBs are considered as substances with high
analgesic activities. One of the best studied natural product,
which contains large amount of cannabinoids, is cannabis,
also known as marijuana. Medicinal marijuana with THC
(tetrahydrocannabinol) as a major constituent is approved
for the supportive care of several medical conditions in
Austria, Belgium, Canada, and several states of the United
States [51].
BCP is a selective agonist of CB2, which is predomi-
nantly expressed on the periphery. Thereby pain modula-
tion by BCP could be largely mediated through
non- neuronal cells. In contrast to anticancer research,
most of the studies on analgesia focus on BCP, since
BCPO does not bind to CB2. However, there is some
evidence that BCPO can exert its antinociceptive action
beyond cannabinoid system machinery.
For reliable evaluation of BCP analgesic properties,
all data described in this review were obtained with use
of animal models of acute or chronic pain. Kuwahata
et al. [52] employed the mouse models of neuropathic
pain to assess whether BCP evokes antinociception
through activation of CB2 or CB1. In these experiments,
the animals were administered with CB2 and CB1
antagonists, AM630 and AM251, respectively, before BCP
injection. The results have shown an inhibition of anal-
gesic effects of BCP by pretreatment with AM630, but
not with AM251, which proved that antiallodynic actions
of BCP are exerted only through activation of local
peripheral CB2. Analgesic efficacy of oral BCP treatment
in mouse models of inflammatory and neuropathic pain
was investigated by Klauke et al. [6]. The antinociceptive
properties of BCP were evaluated on wild- type, CB2(+/+),
and knockout, CB2(−/−), mice. Similarly to studies of
Kuwahata et al. [52], BCP acted as an analgesic agent
by activation of CB2 since antipain effect of BCP was
not observed in CB2(−/−) animals. Interestingly, BCP can
diminish an acute and chronic pain not only through
cannabinoid, but additionally through opioid system.
This was observed in mice after oral administration of
BCP, in which licking and jumping latency in the hot
plate test was increased, whereas pain feeling in the
formalin test was attenuated [53]. In contrast to BCP,
BCPO does not attract much attention as a pain modu-
lator, although it may possess some antinociceptive
properties since Chavan et al. [54] have documented
centrally and peripherally mediated analgesia by BCPO
isolated from Annona squamosa bark extract, in response
to pain stimuli in mice.
Table 1. Concentrations of BCPO and BCP used in in vitro studies of BCP(O) anticancer activities.
Concentration (μg/mL) Cell line Author
BCPO
Isolated from Psidium cattleianum Sabine IC50 0.87 HepG2 Jun et al. [28]
2.98 HeLa
2.77 AGS
3.69 SNU- 1
6.03 SNU- 16
Isolated from Cinnamomum tamala leaves extract
IC50
8.94 A- 2780 Shahwar et al. [29]
7.19 BHK- 21
Purchased from Sigma- Aldrich IC50 57.7 CaCo- 2 Ambrož et al. [31]
Purchased from Jeju National University, Korea 6.6 KBM- 5, H1299, A293, U266, DU145 Kim et al. [37]
Purchased from Jeju National University, Korea 6.6 PC- 3, MCF- 7 Park et al. [40]
Purchased from Jeju National University, Korea 2.2 DU145, MDAMB- 231 Kim et al. [44]
6.6 U266, MM1.S
BCP
Isolated from essential oils of Aquilaria crassna
IC50
3.9 HCT 116 Dahham et al. [30]
5.5 PANC- 1
12.9 HT- 29
19.4 ME- 180
21.3 PC3
21.5 K562
58.2 MCF- 7
IC50 (source unknown) 64 lack of anticancer
effects
DLD- 1/L- 929 Legault, Pichette
[32]
Purchased from Sigma- Aldrich 4.9 × 10−5 BS- 24- 1, MoFir Amiel et al. [33]
BCP(O) concentrations are shown as: IC50, half maximal inhibitory concentration or the lowest concentration used exhibiting antiproliferative/cyto-
toxic activity. BCPO, β- caryophyllene oxide; BCP, β- caryophyllene.
7
© 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.
Sesquiterpenes in Cancer and Analgesia
K. Fidyt et al.
Interestingly, pure BCP displays similar analgesic activities
as several essential oils, in which BCP is a major active
compound. Thus, oils extracted from Dracocephalum kotschyi
[55], Hyptis fruticosa [56], Teucrium stocksianum [57],
Peperomia serpens [58], Vitex agnus-castus [59], and Hyptis
pectinata [60] alleviated pain sensation to similar extent as
BCP, which was shown in rodent pain models such as writh-
ing [55–59], formalin [58–60], hot plate [56], and tail immer-
sion [59] tests. However, it should be noted that essential
oils are mixture of various chemical compounds, which may
potentially modulate the antinociceptive action of BCP.
One can hypothesize that better analgesic effects may
be obtained when BCP is used in combination with other
natural agent(s) of desired properties. For this purpose,
Fiorenzani et al. [61] studied the antinociceptive activity
of BCP in mixture with docosahexaenoic acid (DHA).
DHA is a member of omega- 3 polyunsaturated fatty acids
(PUFAs) and well- known anti- inflammatory mediator [62].
Thus, a combination of BCP and DHA was suspected to
bring a double, analgesic and anti- inflammatory effect in
the treatment of inflammation- associated pain. However,
it turned out that mixture of BCP+DHA did not exert
an additional analgesic activity over that of BCP alone
in animal model of formalin- induced pain. On the other
hand, the same study has revealed that DHA attenuated
BCP toxicity in fibroblasts.
Figure 3. Anticancer and analgesic activities of β- caryophyllene (BCP) and β- caryophyllene oxide (BCPO). BCP and BCPO induce apoptosis and
suppress proliferation of cancer cells as well as reduce levels of tumor angiogenesis and metastasis markers. Molecular mechanisms of BCPO anticancer
activities include activation of mitogen- activated protein kinase (MAPK) pathway as well as inhibition of PI3K/AKT/mTOR/S6K1 and STAT3 signaling.
Additionally, BCP(O) increase cellular accumulation of chemotherapeutic drugs, enhancing their anticancer effectiveness. In response to pain stimuli,
BCP and BCPO reveal different mode of actions. BCP- induced effect of analgesia is obtained with endocannabinoid system (ECS) involvement, while
BCPO analgesic activity is ECS independent. BCP binds to peripheral cannabinoid receptor type 2 (CB2) leading to β- endorphin release from
keratinocytes and activation of opioid receptors. In contrast, antipain effects of BCPO are possibly achieved by inhibition of central pain receptors.
Additionally, both compounds inhibit the release of inflammatory mediators of pain.
8© 2016 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.
K. Fidyt et al.
Sesquiterpenes in Cancer and Analgesia
To understand better the BCP- mediated analgesia, it
is essential to get insight into mechanism of its action.
It still requires elucidation, however current knowledge
about this compound allows for some assumptions to be
made. As phytocannabinoid, it may act in a similar man-
ner to other CB2- selective agonists. CB2 activation can
mediate antinociception either directly or indirectly, where
direct activity is exerted through CB2 stimulation on pri-
mary sensory neurons [63]. In contrast, indirect analgesic
responses are related to inhibition of the release of pro-
inflammatory factors or/and may engage other systems
involved in analgesia, such as endogenous opioid system
[64]. The literature data indicate that CB2- selective agonists
stimulate peripheral release of endogenous opioids such
as β- endorphins, which activates μ- opioid receptors on
primary afferent neurons [65]. In inflammatory hyperal-
gesia, indirect pain inhibition through CB2 localized on
mast and immune cells is possibly achieved by the reduc-
tion of prostanoids or cytokines release, which are respon-
sible for peripheral nociceptor sensitization. Other
CB2- dependent analgesic activities, which are not associated
with inflammation, such as inhibition of nerve injury-
induced sensory hypersensitivity or inhibition of acute
thermal nociception, are still indeterminate [66]. Fernandes
et al. [67] found that BCP derived from essential oil of
Cordia verbenacea exhibited anti- inflammatory properties,
blocking release of proinflammatory molecules, such as
TNFα and prostaglandin E2 (PGE2). The same report
showed BCP- induced decrement in expression of COX- 2
and inducible nitric oxide synthase (iNOS), which could
suppress the NF- κB activation and in a consequence pro-
mote analgesia. In addition, Paula- Freire et al. [53] reported
a decreased level of IL- 1β in the injured sciatic nerve
after BCP treatment, in a model of chronic pain. Another
possible mechanism of BCP pain modulation may be
related to peripheral CB2 simulation and β- endorphin
release from keratinocytes, which was noted after local
and intraplantar injections of BCP in response to capsaicin-
induced nociception. Interestingly, Katsuyama et al. [68]
showed that BCP potentiated an analgesic action of mor-
phine, thereby combination therapy with BCP may be
suggested in order to reduce doses and common side
effects of this opioid agent.
Conclusions
We have presented in this review that natural products,
BCP(O), have strong potential for being used in medical
applications, due to their anticancer and analgesic proper-
ties (Fig. 3). Both compounds could be applied in alter-
native therapy of cancer, supporting the conventional
forms of treatment. Since BCP(O) enhances the efficacy
of some chemotherapeutics, they could be employed in
combination therapy with the classical anticancer drugs.
BCP has also the ability to reduce pain, without causing
psychoactive side effects, as other CB1 agonists do, which
makes it particularly valuable in chronic pain treatment.
Moreover, BCP and BCPO could be used in a mixture
as they often occur in plants. In a medical practice, the
application of such BCP/BCPO mixture in combination
with the classical anticancer drugs could bring many ben-
efits, thus could potentiate the efficacy of used chemo-
therapeutics, elicit the supplementary antineoplastic effect,
as well as reduce the refractory cancer pain at the same
time. However, this potential triple activity of BCP/BCPO
need to be carefully evaluated in animal models of cancer
and cancer pain. Importantly, BCP and BCPO are found
in reasonable amounts in wide range of plants and are
well tolerated at high doses, thus easily accessible and
safe. Despite the fact that both sesquiterpenes can be
potentially useful in medicine, the metabolic, biochemical,
and molecular characteristics of these natural compounds
are still humble and need further investigations.
Acknowledgments
This work was supported by the grant 3/2016 from the
State Committee for Scientific Research, Warsaw, Poland
and the Wroclaw Centre of Biotechnology, program “The
Leading National Research Centre (KNOW) for years
2014–2018.”
Conflict of Interest
None declared.
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