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Bioavailable curcumin formulations: A review of pharmacokinetic studies in healthy volunteers

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Curcumin is a widely studied natural compound which has shown tremendous in vitro therapeutic potential. Despite that, the clinical efficacy of the native curcumin is weak due to its low bioavailability and high metabolism in the gastrointestinal tract. During the last decade, researchers have come up with different formulations with a focus on improving the bioavailability of curcumin. As a result, a significant number of bioavailable curcumin-based formulations were introduced with the varying range of enhanced bioavailability. The purpose of this review is to collate the published clinical studies of curcumin products with improved bioavailability over conventional (unformulated) curcumin. Based on the literature search, 11 curcumin formulations with available human bioavailability and pharmacokinetics data were included in this review. Further, the data on clinical study design, analytical method, pharmacokinetic parameters and other relevant details of each formulation were extracted. Based on a review of these studies, it is evident that better bioavailability of formulated curcumin products is mostly attributed to improved solubility, stability, and possibly low first-pass metabolism. The review hopes to provide a quick reference guide for anyone looking information on these bioavailable curcumin formulations. Based on the published reports, NovaSol® (185), CurcuWin® (136) and LongVida® (100) exhibited over 100-fold higher bioavailability relative to reference unformulated curcumin. Suggested mechanisms accounting for improved bioavailability of the formulations and details on the bioanalysis methods are also discussed.
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Review
Bioavailable curcumin formulations: A review of pharmacokinetic
studies in healthy volunteers
Rohitash Jamwal
Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, USA
article info
Article history:
Received 28 March 2018
Accepted 17 May 2018
Available online 4 July 2018
Keywords:
Curcuma longa
Plant extracts
Curcumin
Human pharmacokinetics
Bioavailability
Liquid chromatography–mass
spectrometer/mass spectrometer
abstract
Curcumin is a widely studied natural compound which has shown tremendous in vitro therapeutic poten-
tial. Despite that, the clinical efficacy of the native curcumin is weak due to its low bioavailability and
high metabolism in the gastrointestinal tract. During the last decade, researchers have come up with dif-
ferent formulations with a focus on improving the bioavailability of curcumin. As a result, a significant
number of bioavailable curcumin-based formulations were introduced with the varying range of
enhanced bioavailability. The purpose of this review is to collate the published clinical studies of cur-
cumin products with improved bioavailability over conventional (unformulated) curcumin. Based on
the literature search, 11 curcumin formulations with available human bioavailability and pharmacokinet-
ics data were included in this review. Further, the data on clinical study design, analytical method, phar-
macokinetic parameters and other relevant details of each formulation were extracted. Based on a review
of these studies, it is evident that better bioavailability of formulated curcumin products is mostly attrib-
uted to improved solubility, stability, and possibly low first-pass metabolism. The review hopes to
provide a quick reference guide for anyone looking information on these bioavailable curcumin
formulations. Based on the published reports, NovaSol
Ò
(185), CurcuWin
Ò
(136) and LongVida
Ò
(100)
exhibited over 100-fold higher bioavailability relative to reference unformulated curcumin. Suggested
mechanisms accounting for improved bioavailability of the formulations and details on the bioanalysis
methods are also discussed.
Please cite this article as: Jamwal R. Bioavailable curcumin formulations: A review of pharmacokinetic
studies in healthy volunteers. J Integr Med. 2018; 16(6): 367–374.
Ó2018 Shanghai Changhai Hospital. Published by Elsevier B.V. All rights reserved.
Contents
1. Introduction . . . ...................................................................................................... 368
2. Methods . . . . . . ...................................................................................................... 368
3. Discussion. . . . . ...................................................................................................... 369
3.1. Overview of bioavailable curcumin formulations . . . . . . . . . . . . . . . . .......................... ............................ 369
3.1.1. Meriva
Ò
................................................................................................ 369
3.1.2. LongVida
Ò
.............................................................................................. 369
3.1.3. CurQfen
TM
............................................................................................... 369
3.1.4. MicroActive curcumin . . . . . . .............................................................................. 369
3.1.5. Micronized curcumin . . . . . . . .............................................................................. 369
3.1.6. NovaSol
Ò
(micellar curcumin) .............................................................................. 370
3.1.7. CurcuWin
Ò
............................................................................................. 370
3.1.8. Biocurcumax
TM
........................................................................................... 370
3.1.9. Curcumin C3 Complex
Ò
+ Bioperine . . . . . . . . . . . . . . ........................................................... 370
3.1.10. Cavacurmin
Ò
........................................................................................... 370
3.1.11. Theracurmin
TM
.......................................................................................... 370
https://doi.org/10.1016/j.joim.2018.07.001
2095-4964/Ó2018 Shanghai Changhai Hospital. Published by Elsevier B.V. All rights reserved.
E-mail address: rohitash@my.uri.edu
Journal of Integrative Medicine 16 (2018) 367–374
Contents lists available at ScienceDirect
Journal of Integrative Medicine
journal homepage: www.jcimjournal.com/jim
www.journals.elsevier.com/journal-of-integrative-medicine
3.2. Comparison of different study parameters . . . . . . . . . . . . . . . ............. ............................................... 370
3.2.1. Clinical study design . . . . ................................................................................. 370
3.2.2. Curcumin administration . ................................................................................. 371
3.2.3. Analysis method and quantification of curcumin. . . . . . . . . . . . . . . . . .............................................. 371
3.2.4. Pharmacokinetic parameters . . . . . . . . . . . . . . ................................................................. 372
3.2.5. RB .................................................................................................... 372
3.3. Limitations. . . . . . ................................... ............................................................ 373
4. Conclusion . ......................................................................................................... 373
Conflict of interest . . . . . . . . . . . ......................................................................................... 373
References . ......................................................................................................... 373
1. Introduction
Curcuma longa Linn. (Zingiberaceae), also known as turmeric, is
a perennial plant native to tropical regions of South Asia. Since
ages, the rhizomes of the plant have been used in Indian (Ayur-
veda) and Chinese medicine system as a remedy for a variety of ail-
ments. Traditionally, curcumin is widely used as a spice, food
preservative, and a coloring agent. Many curcumin-based products
which includes capsules, ointments, tablets, cosmetics are
currently marketed worldwide. Curcumin (diferuloylmethane;
1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) is
a primary, orange hydrophobic polyphenol pigment obtained from
C. longa rhizome [1]. Other reported constituents of curcumin
include demethoxycurcumin, bisdemethoxycurcumin and volatile
oils [1]. Commercially available curcumin contains a mixture of
75% curcumin, 15% demethoxycurcumin, and 5% bisdemethoxy-
curcumin (about 5%) [2]. However, the focus of this review is
limited to highly abundant curcumin.
Extensive research on curcumin over the past decade has
demonstrated the ability of this compound to modulate multiple
cellular targets, and hence potential as a preventive and therapeu-
tic against a broad range of diseases. The compound possesses a
broad range of biological activities (Fig. 1) that include antioxidant,
anti-inflammatory, antiviral, antibacterial, antifungal, and anti-
cancer activities [3]. A large number of in vitro studies on curcumin
have highlighted its antioxidant [4], anti-inflammatory [5], anti-
cancer [1], antiproliferative [6], nephroprotective [7], neuroprotec-
tive [8], hepatoprotective [9], immunomodulatory [10], and
chemopreventive effects [11]. Also, in vitro studies have reported
that curcumin modulates multiple cell signaling pathways, down-
regulates cell survival gene products, upregulates p53, p21 and p27
and induce apoptosis [12–14]. An in-depth review of the therapeu-
tic roles of curcumin has been previously published elsewhere
[15]. Curcumin is currently marketed as a dietary supplement in
many countries worldwide and also carries a generally recognized
safe status. However, despite the proven preclinical efficacy, poor
solubility, low absorption from the gut, rapid metabolism, and
rapid systemic elimination contribute to an overall low oral
bioavailability [16]. Curcumin is a hydrophobic molecule with a
logP of 3.2, which makes it practically insoluble in water [17].
Further, curcumin has a reported half-life of 10 min in phosphate
buffer at physiological pH (7.4) because of its high instability in
alkaline pH [18]. This further limits the therapeutic potential of
curcumin and continues to be a primary concern in its clinical
use. Even after taking gram doses of curcumin, very low plasma
curcumin levels were detected for conventional curcumin [19].
Over the past few years, enormous emphases have been laid on
improving the bioavailability of plant extracts of human benefit
using various pharmaceutical means. Maximizing oral bioavailabil-
ity directly influences plasma concentration as well as the thera-
peutic effects of a compound. Basic thumb rule of all the
approaches is to improve the solubility and hence the bioavailabil-
ity of curcumin. An increase in oral bioavailability is expected to
directly influence plasma concentration as well as therapeutic
effects of curcumin. This will result in lowering of the curcumin
doses and the dose frequency. A large number of approaches have
been utilized to increase the solubility and subsequently the
bioavailability of curcumin [20]. Few of the strategies adopted for
improving the bioavailability of curcumin include curcumin–
piperine complex, curcumin nanoparticles, cyclodextrin inclusions,
curcumin liposomes, and curcumin phospholipids’ complex [3].
The last study reviewing the clinical research on curcumin focused
on the preclinical and clinical pharmacological reports was pub-
lished in 2009 [21]. Since then, a variety of curcumin formulations
have been developed, and subsequent clinical studies with
improved bioavailability have been published. While a large num-
ber of such formulations are developed in academia and as garage
projects, only a few of them are available in the market in one form
or another. Significant differences in study design, volunteer eth-
nicity, methods of sample analysis, sampling time and product
administration were noted.
2. Methods
A literature search was conducted on PubMed/MEDLINE,
Embase, Google Scholar, Cochrane Library and EBSCO between
January 2017 and November 2017. There was no restriction placed
during searches regarding the language, region, or time of publica-
tion. Search terms used to collect the references from electronic
search were ‘‘bioavailable curcumin,” ‘‘curcumin bioavailability,”
and ‘‘curcumin clinical study.” The abstracts of relevant reviews
were inspected, and only pharmacokinetic investigations in
healthy human volunteers were retrieved for the final data extrac-
tion. All the in vitro and animal studies were excluded. Clinical
studies with formulations which are commercially available in
one form or other were selected for this review. Eleven curcumin
formulations were finally selected for the review and data were
extracted from published clinical bioavailability studies in human.
Fig. 1. Some of the reported biological activities associated with curcumin.
368 R. Jamwal / Journal of Integrative Medicine 16 (2018) 367–374
3. Discussion
3.1. Overview of bioavailable curcumin formulations
A detailed table with the curcumin formulations, their major
ingredients, manufacturer and the reported relative bioavailability
(RB) in human is given in Table 1. A significant variation in the
choice of ingredients was observed among the formulations
included in this review. Similarly, it was observed that the strate-
gies used by manufacturers to enhance the bioavailability of cur-
cumin were entirely different too. Increased solubility and
protection from acidic pH (stability) in the gastrointestinal tract
were mainly reported to enhance the bioavailability of curcumin.
3.1.1. Meriva
Ò
Meriva
Ò
is a curcumin-phosphatidylcholine phytosome
complex of soy lecithin, microcrystalline cellulose and 18%–20%
curcuminoids [22]. Curcumin has two phenolic hydroxyls and
one enolic hydroxyl group which can form hydrogen bonds with
complementary polar groups of phospholipids. Once curcumin is
complexed with phosphatidylcholine, the hydrophobic core of
the phytosome protects it from degradation while increasing the
cellular uptake through facilitated diffusion across lipophilic cell
membranes [22,32]. A randomized, double-blind, crossover study
in human found that curcumin absorption was about 29-fold
higher for Meriva
Ò
compared to unformulated curcuminoid mix-
ture [22]. Interestingly, the plasma demethoxycurcumin was found
as a major plasma curcuminoid despite the curcumin content
being four times higher in the formulation. This suggests that
lecithin favors the higher bioavailability of demethoxycurcumin
from Meriva
Ò
.
3.1.2. LongVida
Ò
LongVida
Ò
is a solid lipid curcumin particle (SLCP)-based for-
mulation with improved bioavailability compared to unformulated
curcumin [23]. The curcumin content of LongVida
Ò
is between 20%
and 30%. The SLCP complex protects the curcumin from rapid
degradation and excretion thereby improving the systemic cur-
cumin concentration and half-life [23]. Other formulation parame-
ters such as curcumin/lipid/antioxidant ratio and globule-size
distribution are suggested to extend the absorption of curcumin
from the formulation [23]. LongVida
Ò
is formulated of turmeric
powder with soy lecithin containing purified phospholipids,
docosahexaenoic acid, vegetable stearic acid, ascorbyl (vitamin C)
esters and other insert ingredients [23]. A single-dose, crossover,
double-blind, comparative pharmacokinetic study in healthy
volunteers found its human RB was approximately 100 [23].
3.1.3. CurQfen
TM
CurQfen
TM
is a novel formulation of turmeric powder and soluble
dietary fibers derived from fenugreek (Trigonella foenum-graecum)
[24]. Soluble fibers, composed of galactose and mannose units form
a nondigestible gel hydrocolloid. The hydrocolloid is suggested
to undergoes fermentation in the colon by the action of
b-mannanase and protect against curcumin degradation in the
gastrointestinal tract [33]. The concentration of curcumin in the
formulation is about 40%, and the amorphous formulation delivers
a slow release of stable colloidal curcumin for improved absorp-
tion. In a study in human, oral absorption of curcumin from
CurQfen
TM
at a dose of 1500 mg (equivalent to 600 mg curcumin)
was 15.8 times more bioavailable compared to unformulated cur-
cumin [24]. Prolonged release from nondigestible soluble fibers,
leading to protection from enzymatic degradation gastrointestinal
tract was proposed as a possible mechanism for increased bioavail-
ability of curcumin [24].
3.1.4. MicroActive curcumin
MicroActive curcumin is a micronized formulation of 25% cur-
cuminoids in a proprietary sustained-release matrix consisted of
polyglycerol esters of fatty acids, medium-chain triglycerides,
hydroxypropyl methylcellulose, sodium alginate, and microcrys-
talline cellulose [25]. The surfactants, oil, and polymers in the for-
mulation were suggested to improve the absorption mainly
through a sustained release and stabilization of curcumin in the
intestine [25]. The bioavailability of MicroActive curcumin was
9.7 times as compared to unformulated 95% pure curcumin in a
single-dose bioavailability study in healthy human volunteers [25].
3.1.5. Micronized curcumin
Micronized curcumin is prepared using ‘‘concentrated powder
form” technology and comprises 25% curcumin power, 58% tri-
acetin and 16.7% panodan and further spray drying on porous sili-
con dioxide [26]. The concentration of curcumin in the finished
micronized curcumin powder is 14.1% [26]. The micronized cur-
cumin was 9-fold better bioavailable than unformulated curcumin
in a comparative single-blind crossover study in healthy adult men
and women [26]. Micronization of curcumin was suggested to
improve the absorption. The process reduces the average diameter
Table 1
Composition, manufacturer and reported relative human bioavailability of different formulations.
Formulation Manufacturer Formulation details References
Meriva
Ò
Indena SpA., Italy Phytosome technology (curcumin, soy lecithin, microcrystalline
cellulose, and 18%–20% curcuminoids)
[22]
LongVida
Ò
Verdure Sciences, USA SLCP
TM
technology (solid lipid curcumin particle lipids,
phosphatidylcholine, and 20% curcumin)
[23]
CurQfen
TM
Spiceuticals, India (Akay Group) Fenugreek soluble fiber blend, and 40% curcumin [24]
MicroActive curcumin BioActives LLC, USA 25% curcuminoids, a proprietary mixture of polyglycerol esters of fatty
acids, medium-chain triglycerides, hydroxypropyl methylcellulose,
sodium alginate, and microcrystalline cellulose
[25]
Micronized curcumin Raps GmbH & Co., KG, Germany Micronized powder (58.3% triacetin, 16.7% panodan, and 25% curcumin
powder)
[26]
NovaSol
Ò
Frutarom, Israel Liquid micelles (93% Tween 80, and 7% curcumin powder) [26]
CurcuWin
Ò
OmniActive Health Technologies, India 63%–75% polyvinyl pyrrolidine, 10%–40% cellulosic derivatives, 1%–3%
natural antioxidants, and 20%–28% turmeric extract
[27]
Biocurcumax
TM
(BCM-95
Ò
) Arjuna Natural Extracts Ltd. India
(Dolcas Biotech)
Curcuminoid, essential oil of turmeric (45% ar-turmerone), and
curcuminoids
[28]
Curcumin C3 Complex
Ò
+ Bioperine Sabinsa, USA Bioperine, and curcuminoids [29]
Cavacurmin
Ò
Wacker Chemie AG, Germany
c
-Cyclodextrin, and 15% (w/w) total curcuminoids [30]
Theracurmin
TM
Theravalues Corp., Japan Colloidal-nanoparticles (12% curcuminoids, 46% glycerin, 4% gum
ghatti, 38% water, and 10% curcumin)
[31]
R. Jamwal/ Journal of Integrative Medicine 16 (2018) 367–374 369
of drug particles which improves the rate of dissolution by increas-
ing the surface area to drug ratio [34]. Subsequently, slow diffusion
of drug particle protects it from degradation and improves the
absorption.
3.1.6. NovaSol
Ò
(micellar curcumin)
Micellization is a common technique to improve the solubility
of hydrophilic drugs. NovaSol
Ò
curcumin micelles were formulated
of 7% curcumin powder (6% curcumin) and 93% Tween-80 [26].Ina
single-blind crossover study in healthy adult men and women, the
bioavailability of curcumin from NovaSol
Ò
was 185 folds higher
than that of the same dose of unformulated curcumin [26].
Curcumin incorporated with a nonionic surfactant Tween 80
(polysorbate 80) leads to the formation of liquid micelles which
improves dissolution and absorption.
3.1.7. CurcuWin
Ò
CurcuWin
Ò
is a novel water-soluble curcumin formulation con-
taining 20%–28% turmeric powder, 63%–75% polyvinyl pyrrolidine
(a hydrophilic carrier), 10%–40% cellulosic derivatives and 1%–3%
natural antioxidants [27]. In a randomized, double-blind, crossover
study, the RB of CurcuWin
Ò
was 136 times compared to unformu-
lated curcumin [27]. The increase in oral absorption of the cur-
cumin was attributed to increased solubility similar to other
formulations included in the study. Additionally, tocopherol and
ascorbyl palmitate were suggested to prevent degradation of cur-
cumin [27].
3.1.8. Biocurcumax
TM
Biocurcumax
TM
(BCM-95
Ò
) is a formulation of turmeric powder
and essential oils of turmeric (45% ar-turmerone) [28]. The relative
human bioavailability of the complex in a crossover study was
about 6.9-fold compared to unformulated curcumin [28]. The
improved absorption of curcumin from the formulation was indi-
cated to noncurcuminoid components of turmeric.
3.1.9. Curcumin C3 Complex
Ò
+ Bioperine
Bioperine is one of the first bioavailability enhancers used to
improve the oral absorption of curcumin in humans. Piperine, the
main active constituent of bioperine, is a P-glycoprotein inhibitor
and hence improves the absorption by decreasing the efflux of
absorbed curcumin in the intestine [35]. Bioperine also inhibits
uridine diphosphate-glucuronosyltransferase (UGT) and hence
improves the freely available curcumin in the systemic circulation.
When curcumin was given with piperine (20 mg/kg body weight),
the RB of curcumin was 20-fold compared to curcumin alone [29].
3.1.10. Cavacurmin
Ò
Cavacurmin
Ò
is a
c
-cyclodextrin-based formulation of cur-
cumin developed by Wacker Chemie AG, Germany [30]. Cyclodex-
trins consist of nonreducing chiral glucose-building blocks
arranged in a ring structure with hydrophilic glucose-building
blocks facing outwards which results in a lipophilic cavity on the
inside [36]. Curcumin fits in this lipophilic cavity by weak van
der Waals forces, resulting in an inclusion complex with cyclodex-
trin. The resulting inclusion complexes improve curcumin’s aque-
ous solubility, and hence the absorption. Cavacurmin
Ò
showed an
85-fold increase in bioavailability in comparison to unformulated
curcumin administered in a crossover study in human [30].It
was suggested that Cavacurmin
Ò
is transported unchanged
through the stomach into the upper intestinal tract where cur-
cumin is absorbed while cyclodextrin molecules are hydrolyzed
by human amylases [30].
3.1.11. Theracurmin
TM
Theracurmin
TM
is a colloidal nanoparticle-based formulation of
curcumin. The formulation consists of 10% (w/w) curcumin, 2%
other curcuminoids such as demethoxycurcumin and bis-
demethoxycurcumin, 46% glycerin, 4% gum ghatti, and 38% water
[31]. The colloidal nanoparticle dispersion of curcumin improves
the solubility and its oral bioavailability as found in a human phar-
macokinetic study [31]. The RB of curcumin from Theracurmin
TM
in
healthy volunteers was almost 16 time as compared to unformu-
lated curcumin. The authors reported that gum ghatti was respon-
sible for improving the solubility and stability of curcumin
formulation. Subsequently, wet-grinding of this mixture yields
nanoparticles which are 100 times smaller than the unformulated
curcumin powder. The combination of improved solubility and
reduced particle size enhances the clinical bioavailability of Ther-
acurmin
TM
[31].
3.2. Comparison of different study parameters
3.2.1. Clinical study design
Most studies were conducted with a blinded, randomized cross-
over design (see Table 2 for complete details). Participants in ran-
domized, double-blind studies are randomly assigned to the
treatment group, and neither researchers nor volunteers are aware
of the treatment. It removes bias in the study and is therefore con-
sidered ‘‘gold standard” of clinical trials [37]. A crossover design is
a within-subject design where each participant serves as his/her
control and receives all treatments, where each is separated by
‘‘washout” period in which no treatment is given [38].
Five formulations included in this review were studied in the
Asians and six in Caucasians. Most of the studies had poor gender
balance except for Theracurmin
TM
, NovaSol
Ò
and micronized cur-
cumin. No information on the gender was available for BCM-95
Ò
(Biocurcumax
TM
) study. Three studies (LongVida
Ò
, CurQfen
TM
and
Curcumin C3 Complex
Ò
+ Bioperine) recruited only males whereas
other studies included volunteers from both sexes. The maximum
number of volunteers in a study was 23 (micronized curcumin and
NovaSol
Ò
) and a minimum of six volunteers were recruited for
Table 2
Clinical study design parameters of the different curcumin-based formulations.
Formulation Clinical study design Number of subjects Subject ethnicity References
Meriva
Ò
Randomized, double-blind, crossover 9 (8 males, 1 female) Caucasian [22]
LongVida
Ò
Randomized, crossover, double-blind 6 (all males) Asian (Indian) [23]
CurQfen
TM
Crossover 8 (all males) Asian (Indian) [24]
MicroActive curcumin Crossover 12 (11 males, 1 female) 11 Caucasian, 1 African-American [25]
Micronized curcumin Randomized, double-blind, crossover 23 (10 males, 13 females) Caucasian [26]
NovaSol
Ò
Randomized, double-blind, crossover 23 (10 males, 13 females) Caucasian [26]
CurcuWin
Ò
Randomized, double-blind, crossover 12 (11 males, 1 female) 11 Caucasian, 1 African-American [27]
Biocurcumax
TM
(BCM-95
Ò
) Crossover 11 (gender not reported) Asian (Indian) [28]
Curcumin C3 Complex
Ò
+ Bioperine Randomized, crossover 10 (all males) Asian (Indian) [29]
Cavacurmin
Ò
Randomized, double-blind, crossover 12 (11 males, 1 female) 11 Caucasian, 1 African-American [30]
Theracurmin
TM
Randomized, crossover 14 (8 males, 6 females) Asian (Japan) [31]
370 R. Jamwal / Journal of Integrative Medicine 16 (2018) 367–374
LongVida
Ò
pharmacokinetic study. Schiborr et al. [26] found that
systemic concentration of curcumin was higher in women than
men dosed with Novasol
Ò
and micronized curcumin. The details
on the ethnicity, gender, and the number of subjects for these stud-
ies are given in Table 2.
3.2.2. Curcumin administration
Conventional (unformulated) or formulated curcumin was
administered orally in all the studies. The composition and content
of food given to volunteers after administration of curcumin dose
differed significantly. Except for Theracurmin
TM
, volunteers were
fasted overnight before getting the drug, and the curcumin-free
food was provided after drug administration. No information on
fasting status and meals provided to subjects was reported by
authors in the Theracurmin
TM
study [31]. CurcuWin
Ò
and Cavacur-
min
Ò
were given to overnight fasted individuals who were fed first
meal 4 h after administration of curcumin [27,30]. In contrast,
Cuomo et al. [22] gave a high-fat meal immediately after curcumin
(Meriva
Ò
) administration. MicroActive curcumin and NovaSol
Ò
were administered after subjects were given breakfast (30% fat)
[26]. It is worth reiterating here that high-fat meal diet is known
to increase the mean transit time in the intestine and may thereby
enhance the exposure of the drug for absorption [39].
3.2.3. Analysis method and quantification of curcumin
A significant variation in the analysis of curcumin in human
plasma was seen in the trials (Table 3). While some studies used
high-performance liquid chromatography for quantification, others
utilized liquid chromatography–mass spectrometer (LC–MS).
Separation of curcumin was achieved by reverse-phase liquid chro-
matography in all the studies. Plasma was used for quantification
of curcumin in all the studies except the one with piperine where
serum was utilized [29]. Despite the fact that curcumin is
extensively conjugated by UGT after absorption [40], studies with
CurQfen
TM
, LongVida
Ò
, Curcumin C3 Complex
Ò
+ Bioperine and
Biocurcumax
TM
measured free curcumin in the plasma. It is inter-
esting to note here that quantification of free curcumin in these
studies is mainly at odd with the previous pharmacokinetic studies
in rat and human. It appears that in those formulations where free
curcumin was measured, the formulation per se hindered the
direct access of curcumin (to UGT) and protected from conjugation.
Conversely, in all other studies, plasma was hydrolyzed before
quantification of curcumin. The hydrolysis of conjugated curcumin
in plasma was achieved using b-glucuronidase/sulfatase from Helix
pomatia which has been historically used for quantification of
glucuronide-bound compounds [41]. Glucuronidase liberates the
hydrophilic aglycone moiety attached to curcumin by UGT and
allows for quantification of curcumin. None of the studies which
hydrolyzed the plasma samples quantified the free curcumin in
plasma without hydrolysis. Initial aglycone curcumin should have
been subtracted from deconjugated curcumin as that would have
allowed more meaningful data to the researchers.
Liquid–liquid extraction of curcumin from plasma was adopted
by all the studies in the review. Methanol, chloroform, ethyl acet-
ate and a mixture of ethyl acetate with methanol were among the
solvents used for extraction of curcumin. The choice of solvent for
extraction of curcumin and its conjugates is debatable. As cur-
cumin is a lipophilic compound, use of ethyl acetate is an ideal sol-
vent for the extraction of free curcumin from plasma. However, the
conjugation of glucuronic acid to curcumin by UGT makes it hydro-
philic and would lead to suboptimal extraction with ethyl acetate.
Alternatively, a 1:1 (v/v) mixture of ethyl acetate/diethyl ether can
be used for extraction of free and conjugated curcumin from
plasma [41]. Acetonitrile and methanol also extract a significant
number of phospholipids from plasma. Methyl tert-butyl ether
and n-butyl chloride remove the negligible amount of plasma
Table 3
Analytical methods and related parameters of the different curcumin-based formulations.
Formulation Analysis technique Internal standard Sample hydrolysis Extraction solvent Analyte measured References
Meriva
Ò
HPLC–MS/MS Not used Hydrolysis, b-glucuronidase/sulfatase Ethyl acetate Free curcumin after hydrolysis [22]
LongVida
Ò
HPLC-PDA Not used No hydrolysis Methanol Free curcumin [23]
CurQfen
TM
HPLC-UV Not used No hydrolysis Ethyl acetate Free curcumin [24]
MicroActive curcumin HPLC-UV Not used Hydrolysis, b-glucuronidase/sulfatase 95% Ethyl acetate + 5% methanol Free curcumin after hydrolysis [25]
Micronized curcumin HPLC-fluorescence Not used Hydrolysis, b-glucuronidase/sulfatase 95% Ethyl acetate + 5% methanol Free curcumin after hydrolysis [26]
NovaSol
Ò
HPLC-fluorescence Not used Hydrolysis, b-glucuronidase/sulfatase 95% Ethyl acetate + 5% methanol Free curcumin after hydrolysis [26]
CurcuWin
Ò
HPLC–MS/MS Salbutamol Hydrolysis, b-glucuronidase/sulfatase Ethyl acetate Free curcumin after hydrolysis [27]
Biocurcumax
TM
(BCM-95
Ò
) HPLC-UV Not used No hydrolysis Ethyl acetate Free curcumin [28]
Curcumin C3 Complex
Ò
+ Bioperine HPLC-UV Not used No hydrolysis Methanol
*
Free curcumin [29]
Cavacurmin
Ò
HPLC–MS/MS Salbutamol Hydrolysis, b-glucuronidase/sulfatase Ethyl acetate Free curcumin after hydrolysis [30]
Theracurmin
TM
HPLC–MS/MS Mepronil Hydrolysis, b-glucuronidase/sulfatase Chloroform Free curcumin after hydrolysis [31]
*
Used the serum for quantification of curcumin. HPLC: high-performance liquid chromatography; MS: mass spectrometer; PDA: photodiode array; UV: ultraviolet.
R. Jamwal/ Journal of Integrative Medicine 16 (2018) 367–374 371
phospholipids and should be considered by researchers in future
studies [42]. We and others have previously described in detail
the methodology to study matrix effects including common phos-
pholipid transitions to be monitored [42,43]. Elution of curcumin
at the same retention time of phospholipids should be avoided,
and chromatographic conditions should be modified accordingly
to separate the compound of interest and co-eluting phospholipids.
Nowadays, hydrolysis can be avoided altogether, and free cur-
cumin and conjugated curcumin can be simultaneously quantified
on selective and sensitive LC–MS/MS instruments. Pure standards
of curcumin’s conjugates are commercially available. This offers a
quick and simple sample preparation without the need of hydrol-
ysis step which can introduce variability due to incomplete hydrol-
ysis of the curcumin conjugates among samples. Also, curcumin
conjugates are bound significantly to plasma proteins and can
add to the variability in hydrolysis efficiency.
It is worth mentioning that most studies did not use an internal
standard during the analysis of the plasma or serum samples from
the bioavailability studies. This is a significant shortcoming in
these studies as an internal standard improves the accuracy, preci-
sion, and robustness of the quantitative assay [44]. Interestingly,
salbutamol was used as internal standard in CurcuWin
Ò
and
Cavacurmin
Ò
clinical studies, and mepronil was used in Theracur-
min
TM
study [27,31].
3.2.4. Pharmacokinetic parameters
Absorption, distribution, metabolism, and excretion determine
the fate of a drug after administration. The oral bioavailability of
a drug is the fraction of administered drug that reaches systemic
circulation escaping the first-pass metabolism in the intestine
and liver. Besides hepatic and intestinal metabolism, oral bioavail-
ability is also dependent on several other factors. Such important
factors include physicochemical properties of the drug, degrada-
tion in the lumen, lipophilicity of the drug, gastric emptying time
and dose. The information on pharmacokinetic parameters of dif-
ferent formulations is tabulated in Table 4.
The maximum observed systemic concentration of a drug is ter-
med as C
max
(maximum drug concentration) whereas the time to
reach this level is called T
max
, time to reach maximum drug con-
centration; C
max
represents the rate at which a compound is
absorbed; the area under the drug concentration–time curve
(AUC) denotes the extent of absorption of the drug. AUC is often
used to compare the RB of a new formulation with a reference
product. A direct comparison of AUC, T
max
, and C
max
among the for-
mulations is not possible due to variability in the dose of curcumin
administered. However, it is evident from the Table 4 that all the
curcumin formulations significantly increased the AUC and C
max
when compared to unformulated curcumin. As AUC is dependent
on the rate of elimination and administered dose of a drug, it is evi-
dent that formulating curcumin prolongs the systemic exposure. It
is important to note that while some formulations increased the
T
max
, others had an opposite effect. The T
max
for unformulated
curcumin (control) among the different studies ranged from 0.5
to 12 h showing almost a 15-fold difference. In contrast, for
bioavailable formulations, T
max
ranged from 0.69 to 8.8 h among
formulations with an approximately 12-fold range.
3.2.5. RB
AUC presents a more reliable measure of bioavailability com-
pared to C
max
as it takes into account the systemic exposure of drug
Table 4
Pharmacokinetic parameters of curcumin from the different curcumin-based formulations and reference (unformulated curcumin).
Formulation Intervention Dose C
max
(ng/mL) T
max
(h) AUC
0–t
(ng h/mL) t
1/2
(h) RB
curcumin
References
Meriva
Ò
Formulation
a
297 mg curcumin 50.3 ± 12.7 3.8 ± 0.6 538.0 ± 130.7
1
NR 48 [22]
Control
a
1295 mg curcumin 9.0 ± 2.8 6.9 ± 2.2 122.5 ± 29.3
1
NR
LongVida
Ò
Formulation
a
650 mg curcuminoids 22.4 ± 1.9 2.4 ± 0.4 95.3 ± 4.6
1
7.5 ± 2.4 100 [23]
Control
a
650 mg curcuminoids < 1 ND ND ND
CurQfen
TM
Formulation
b
600 mg curcumin 0.4 ± 0.2 (mg/g) 1 8100 ± 287
2
(mgh/g) NR 15.8 [24]
Control
b
1000 mg curcumin 0.02 ± 0.01 (mg/g) 0.5 510 ± 123
2
(mgh/g) NR
MicroActive
curcumin
Formulation
c
500 mg curcumin NR 4
d
887.5 ± 549.9
3
NR 9.7 [25]
Control
c
500 mg curcumin NR NR 91.8 ± 50.0
3
NR
Micronized
curcumin
Formulation
b
410 mg curcumin 15.3 ± 8.9 8.8 ± 6.4 214.6 ± 106.4
3
NR 9 [26]
Control
b
410 mg curcumin 2.6 ± 4.9 7.5 ± 8.2 24.1 ± 42.6
3
NR
NovaSol
Ò
Formulation
b
410 mg curcumin 1189.1 ± 518.7 1.1 ± 0.4 4474.7 ± 1675.2
3
NR 185 [26]
Control
b
410 mg curcumin 2.6 ± 4.9 7.5 ± 8.2 24.1 ± 42.6
3
NR
CurcuWin
Ò
Formulation
a
376 mg curcuminoids 27.3 ± 6.4 1.4 ± 0.5 307.6 ± 44.6
3
NR 136.3 [27]
Control
a
1800 mg total curcuminoids 2.3 ± 0.3 7.4 ± 1.0 10.8 ± 1.7
3
NR
Biocurcumax
TM
(BCM-95
Ò
)
Formulation
c
2000 mg curcuminoids 456.9
d
(mg/g) 3.44
d
3201.3
d4
(mgh/g) 4.96
d
27 [28]
Control
c
2000 mg curcuminoids 149.8
d
(mg/g) 2
d
461.9
d4
(mgh/g) 2.63
d
Curcumin C3
Complex
Ò
+
Bioperine
Formulation
a
2000 mg curcumin with
bioperine
180 ± 30 0.69 ± 0.07 80 ± 10
5
0.11 ± 0.02 20 [29]
Control
a
2000 mg curcumin 6 ± 5 1
d
4
d5
NR
Cavacurmin
Ò
Formulation
a
376 mg curcuminoids 73.2 ± 17.5 1
d
327.7 ± 58.1
3
NR 85 [30]
Control
a
1800 mg total curcuminoids ND 12
d
3.9 ± 0.5
3
NR
Theracurmin
TM
Formulation
b
30 mg curcumin 29.5 ± 12.9 1
d
113 ± 61
2
NR 15.9 [31]
Control
b
30 mg curcumin 1.8 ± 2.0 6
d
4.1 ± 7.0
2
NR
Control: unformulated curcumin.
NR: not reported; ND: not detected; AUC: area under the drug concentration–time curve; C
max
: maximum drug concentration; RB: relative bioavailability; T
max
: time at
maximum drug concentration.
a
Mean ± standard error of mean.
b
Mean ± standard deviation.
c
Mean.
d
No reported standard deviation or error.
1
AUC
0–t
.
2
AUC
0–24
.
3
AUC
0–12
.
4
AUC
0–inf
.
5
AUC
0–6
.
372 R. Jamwal / Journal of Integrative Medicine 16 (2018) 367–374
over time. In contrast, C
max
measures only one-time point and is
less robust to gauge the extent of total absorption. Therefore, RB
of formulated curcumin compared to unformulated curcumin
was used to determine the improvement in the absorption. The
RB was calculated using the equation given below:
RB ¼ðAUC
0t
FCÞðDose UCÞ
ðAUC
0t
UCÞðDose FCÞ
where Dose UC is the dose of unformulated curcumin, Dose FC rep-
resents dose of formulated curcumin and AUC
0-t
represents the area
under the curve over time (0–t) for formulated curcumin (FC) and
unformulated curcumin (UC), respectively.
RB ranged from 9 to 185 among the eleven bioavailable cur-
cumin formulations (Fig. 2). NovaSol
Ò
(185-fold) was reported
with highest RB compared to unformulated curcumin, and Micro-
nized curcumin (9-fold) with the least (Table 4). Micelle-based cur-
cumin formulation NovaSol
Ò
was reported to escape phase
separation in gastrointestinal tract, delivering most of the cur-
cumin to the intestinal wall for absorption. CurcuWin
Ò
and Long-
Vida
Ò
were also reported to have 100-fold bioavailability
relative to conventional unformulated curcumin, suggesting that
approaches which increase the total surface area significantly,
improve the bioavailability.
3.3. Limitations
Interestingly, a substantial difference in the pharmacokinetic
parameters of curcumin from different formulations could be
attributed to dissimilarities in dose, formulation, clinical design,
analysis methods and populations in which the formulations were
studied. Significant differences in the sampling time after oral
administration in these studies may impact the AUC, C
max
and
T
max
. The different gastric emptying time contributes significantly
to the interindividual and interpopulation variability in drug
absorption from the intestine. Therefore, the choice of food and
time after which the meal was provided to volunteer may also
impact the bioavailability and is another constraint when compar-
ing these studies. An accurate comparison of different formulations
can only be achieved by a large crossover study, comparing differ-
ent formulations, using the same analytical method (free or conju-
gated curcumin) and a same method of administration (fasted or
nonfasted, ethnicity). Such studies have been attempted in the past
but only a handful of formulations were studied, and results were
often different than the one reported by original articles due to the
reasons listed above [27,30].
4. Conclusion
Curcumin’s health benefits are limited due to poor solubility
and pharmacokinetics. Efforts are currently made by different
research groups to improve the bioavailability of curcumin to har-
ness the proven in vitro efficacy and therapeutic promise. The
recent decade has seen a rise in curcumin-based formulations
addressing its solubility and stability. However, extensive variabil-
ity in the studies makes it difficult to directly compare and con-
clude which formulation is better than the other. The absolute
values of these studies are difficult to compare due to variances
in study design, population, analytical methods, and administra-
tion of the product. Harmonized large clinical studies in human
are needed to investigate how these curcumin formulations com-
pare to each other but remain a constraint due to monetary and
commercial reasons.
Conflict of interest
The review provides author’s perspective of these curcumin for-
mulations and has no conflict of interest to declare.
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... First, interspecies differences notwithstanding, the administered dose, type of solvent/vehicle, experimental design, and analytical method may differentially affect PK parameters. 74 This is illustrated by the rather wide relative concentration range per time point as presented in Figure 2. Some of the solvents/solubilizers that were used are micelleforming surfactants (such as Kolliphore and Tween) that may prolong the systemic presence of curcumin. The consequences of curcumin solubilization by these excipients before or after intravenous administration on PK are further elaborated in section S3.1. ...
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Curcumin is a natural anti-inflammatory agent that has been used for treating medical conditions for many years. Several experimental and pharmacologic trials have demonstrated its efficacy in the role as an anti-inflammatory agent. Curcumin has been shown to be effective in treating chronic conditions like rheumatoid arthritis, inflammatory bowel disease, Alzheimer's and common malignancies like colon, stomach, lung, breast, and skin cancers. As treatments in medicine become more and more complex, the answer may be something simpler. This is a review article written with the objective to systematically analyze the wealth of information regarding the medical use of curcumin, the “curry spice”, and to understand the existent gaps which have prevented its widespread application in the medical community.
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Curcumin, a pigment from turmeric, is one of the very few promising natural products that has been extensively investigated by researchers from both the biological and chemical point of view. While there are several reviews on the biological and pharmacological effects of curcumin, chemistry reviews are comparatively scarcer. In this article, an overview of different aspects of the unique chemistry research on curcumin will be discussed. These include methods for the extraction from turmeric, laboratory synthesis methods, chemical and photochemical degradation and the chemistry behind its metabolism. Additionally other chemical reactions that have biological relevance like nucleophilic addition reactions, and metal chelation will be discussed. Recent advances in the preparation of new curcumin nanoconjugates with metal and metal oxide nanoparticles will also be mentioned. Directions for future investigations to be undertaken in the chemistry of curcumin have also been suggested.
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The potential health benefits of curcumin are limited by its poor solubility, low absorption from the gut, rapid metabolism and rapid systemic elimination. The purpose of this study was the comparative measurement of the increases in levels of curcuminoids (curcumin, demethoxycurcumin, bisdemethoxycurcumin) and the metabolite tetrahydrocurcumin after oral administration of three different curcumin formulations in comparison to unformulated standard. The relative absorption of a curcumin phytosome formulation (CP), a formulation with volatile oils of turmeric rhizome (CTR) and a formulation of curcumin with a combination of hydrophilic carrier, cellulosic derivatives and natural antioxidants (CHC) in comparison to a standardized curcumin mixture (CS) was investigated in a randomized, double-blind, crossover human study in healthy volunteers. Samples were analyzed by HPLC-MS/MS. Total curcuminoids appearance in the blood was 1.3-fold higher for CTR and 7.9-fold higher for CP in comparison to unformulated CS. CHC showed a 45.9-fold higher absorption over CS and significantly improved absorption over CP (5.8-fold) and CTR (34.9-fold, all p < 0.001). A formulation of curcumin with a combination of hydrophilic carrier, cellulosic derivatives and natural antioxidants significantly increases curcuminoid appearance in the blood in comparison to unformulated standard curcumin CS, CTR and CP.
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Chapter
Internal standards (ISs) are commonly used in liquid chromatography-mass spectrometry (LC-MS) bioanalysis. The main purpose of utilizing ISs is to improve the accuracy and precision of quantitation as well as the robustness of bioanalytical methods. The accuracy and precision of reported concentrations and the reliability of bioanalytical methods can be significantly improved through the proper use of a good IS. Then, what is a good IS? How should its concentration be determined? When and how should it be added? Why are stable isotope labeled ISs preferred yet one should still be cautious in their usage? Should IS responses be monitored during incurred sample analysis? What are the root causes of IS response variations? What are their potential impacts on the integrity of reported concentrations? These questions are addressed in this chapter with a focus on small molecules (molecular weights typically less than 1000 Da).
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The essential oil composition and total phenolic content (TPC) of curcuminoids were studied in rhizomes of nine Curcuma longa L. accessions. Curcuminoids, present in commercially available turmeric rhizomes, play vital roles in various pharmacological activities. A simple, rapid, and sensitive high performance liquid chromatography photodiode array (HPLC-PDA) method was optimized for simultaneous determination of curcuminoids, namely, a mixture of curcumin, demethoxy curcumin (DMC), and bisdemethoxy curcumin (BDMC) in rhizomes of C. longa. Chromatographic separation was performed on an RP C18 column within 13 minutes (11.4 to 12.95 minutes). Elution was accomplished by the application of acetonitrile and 1.5% acetic acid in water in a gradient system with flow rate of 2.0 mL min−1. PDA was employed for qualitative and quantitative analysis. The calibration curves were found linear (0.99) for all cucuminoids; the limit of detection and quantification ranged between 1.01 µ g mL−1 to 1.16 µ g mL−1 and 2.30 µ g mL−1 to 3.05 µ g mL−1, respectively, while recovery values ranged between 97.97% to 98.32%. The amount of curcumin varied from 0.46% to 2.17%, DMC from 0.13% to 0.92% and BDMC from 0.06% to 0.52%. The validated method was successively used to determine the above compounds in C. longa rhizomes. The TPC in rhizomes ranged from 14.12 mg g−1 to 27.72 mg g−1. The chemical composition of rhizome essential oil, analyzed by gas chromatography mass spectrometry (GCMS,) showed large variations in major compounds like ar-tumerone (7.31–38.66%), β-curcumene (1.58–24.53%), and curlone (1.55–15.97%).