Glycyrrhiza glabra extract and quercetin reverses cisplatin resistance in triple-negative MDA-MB-468 breast cancer cells via inhibition of cytochrome P450 1B1 enzyme

Article abstract of DOI:10.1016/j.bmcl.2017.11.013

The development of multi-drug resistance to existing anticancer drugs is one of the major challenges in cancer treatment. The over-expression of cytochrome P450 1B1 enzyme has been reported to cause resistance to cisplatin. With an objective to discover cisplatin-resistance reversal agents, herein, we report the evaluation of Glycyrrhiza glabra (licorice) extracts and its twelve chemical constituents for inhibition of CYP1B1 (and CYP1A1) enzyme in Sacchrosomes and live human cells. The hydroalcoholic extract showed potent inhibition of CYP1B1 in both Sacchrosomes as well as in live cells with IC₅₀ values of 21 and 16 μg/mL, respectively. Amongst the total of 12 constituents tested, quercetin and glabrol showed inhibition of CYP1B1 in live cell assay with IC₅₀ values of 2.2 and 15 μM, respectively. Both these natural products were found to be selective inhibitors of CYP1B1, and does not inhibit CYP2 and CYP3 family of enzymes (IC₅₀ > 20 μM). The hydroalcoholic extract of G. glabra and quercetin (4) showed complete reversal of cisplatin resistance in CYP1B1 overexpressing triple negative MDA-MB-468 breast cancer cells. The selective inhibition of CYP1B1 by quercetin and glabrol over CYP2 and CYP3 family of enzymes was studied by molecular modeling studies.

Full text of DOI:10.1016/j.bmcl.2017.11.013

Accepted Manuscript
Glycyrrhiza glabra extract and quercetin reverses cisplatin resistance in triple-
negative MDA-MB-468 breast cancer cells via inhibition of cytochrome P450
1B1 enzyme
Rajni Sharma, Linda Gatchie, Ibidapo S. Williams, Shreyans K. Jain, Ram A.
Vishwakarma, Bhabatosh Chaudhuri, Sandip B. Bharate
PII:
S0960-894X(17)31100-9
https://doi.org/10.1016/j.bmcl.2017.11.013
BMCL 25419
DOI:
Reference:
Bioorganic & Medicinal Chemistry Letters
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2 November 2017
6 November 2017
Please cite this article as: Sharma, R., Gatchie, L., Williams, I.S., Jain, S.K., Vishwakarma, R.A., Chaudhuri, B.,
Bharate, S.B., Glycyrrhiza glabra extract and quercetin reverses cisplatin resistance in triple-negative MDA-
MB-468 breast cancer cells via inhibition of cytochrome P450 1B1 enzyme, Bioorganic & Medicinal Chemistry
Letters (2017), doi: https://doi.org/10.1016/j.bmcl.2017.11.013
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Glycyrrhiza glabra extract and quercetin reverses
cisplatin-resistance in triple-negative MDA-MB-
468 breast cancer cells via inhibition of
cytochrome P450 1B1 enzyme
Rajni Sharma, Linda Gatchie, Ibidapo S. Williams, Shreyans K. Jain, Ram A. Vishwakarma, Bhabatosh Chaudhuri and
Sandip B. Bharate*
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Bioorganic & Medicinal Chemistry Letters
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Glycyrrhiza glabra extract and quercetin reverses cisplatin resistance in triple-negative
MDA-MB-468 breast cancer cells via inhibition of cytochrome P450 1B1 enzyme
Rajni Sharma,a,b,# Linda Gatchie,c,# Ibidapo S. Williams,c Shreyans K. Jain,a,b Ram A. Vishwakarma,be Bhabatosh Chaudhuri,c,*
Sandip B. Bharatebe*
aNatural Products Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu-180001, India
bAcademy of Scientific & Innovative Research (AcSIR), CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu-180001, India
cLeicester School of Pharmacy, De Montfort University, Leicester UK
eMedicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu-180001, India
ARTICLE INFO
ABSTRACT
The development of multi-drug resistance to existing anticancer drugs is one of the major
challenges in cancer treatment. The over-expression of cytochrome P450 1B1 enzyme has
been reported to cause resistance to cisplatin. Herein, we report the evaluation of
Glycyrrhiza glabra (licorice) extracts and its twelve chemical constituents for inhibition of
CYP1B1 (and CYP1A1) enzyme in Sacchrosomes and live human cells. The hydroalcoholic
extract showed potent inhibition of CYP1B1 in both Sacchrosomes as well as in live cells
with IC50 values of 21 and 16 µg/mL, respectively. Amongst the total of 12 constituents
tested, quercetin and glabrol showed inhibition of CYP1B1 in live cell assay with IC50 values
of 2.2 and 15 µM, respectively. Both these natural products were found to be selective
inhibitors of CYP1B1, and does not inhibit CYP2 and CYP3 family of enzymes (IC50 > 20
µM). The hydroalcoholic extract of G. glabra and quercetin (4) showed complete reversal of
cisplatin resistance in CYP1B1 overexpressing triple negative MDA-MB-468 breast cancer
cells. The selective inhibition of CYP1B1 by quercetin and glabrol over CYP2 and CYP3
family of enzymes was studied by molecular modeling studies.
Article history:
Received
Received in revised form
Accepted
Available online
Keywords:
Cisplatin-resistance,
CYP1B1,
Glycyrrhiza glabra,
quercetin,
glabrol,
MDA-MB-468 cells
2017 Elsevier Ltd. All rights reserved.
Chemotherapy is one of the key approaches for treatment of cancers.
Chemotherapeutic drugs are used to reduce the size / progression of
tumor growth; however, with most of these drugs, their eventual
ability to reduce tumor growth decreases because of various
resistance mechanisms. Cisplatin is an anticancer drug commonly
employed in the treatment of many advanced cancers including
breast cancer. Nevertheless, it develops resistance over a period of
time, resulting in treatment failure.1-3 The overexpression of human
cytochrome P450 CYP1B1 has been identified as one of the
important factors responsible for development of cisplatin-
resistance.4-5 Studies have demonstrated that the use of CYP1B1
inhibitors in combination with cisplatin, has resulted in reversal of
this resistance.6
constituents against CYP2B6, CYP2C8, CYP2C9, CYP2C19 and
CYP3A4 in order to understand their potential role in drug-drug
interactions. However, the potential of licorice and its chemical
constituents to overcome cisplatin-resistance has never been
reported. Herein, we report the CYP1B1/ CYP1A1 inhibitory
activity of hydroalcoholic extract of G. glabra and its 12 chemical
constituents which is followed by studies on their ability to
overcome cisplatin-resistance in breast cancer cells, and protection
against toxicity mediated by a procarcinogen.
The roots of G. glabra were extracted with ethanol and ethanol-water
to obtain an EtOH extract (GG-A003) and a hydroalcoholic extract
(GG-A002). Both prepared extracts were tested for CYP1A1 and
CYP1B1 inhibition in Sacchrosomes (yeast microsomes) followed
by screening in live human cells. Results are shown in Table 1. It
was observed that both extracts showed similar level of activity with
respect to inhibition of CYP1B1 enzyme. As routine practice, the
microsomes were used to study the effect of compounds on
cytochrome P450 enzymes; however, results obtained from these
studies may lead sometimes to false-negative inferences. Therefore,
to gain a realistic picture of cytochrome P450 inhibition, we have
established a live cell based assay system in human HEK293 cells
which were transfected with plasmids bearing the human CYP1B1
and CYP1A1 genes. Both extracts GG-A002 and GG-A003 displayed
CYP1B1 as well as CYP1A1 inhibitory activity in live cells. The
EC50 values were found to be in the range of 16-20 µg/mL (Table 1).
The licorice (Glycyrrhiza glabra) has been reported to possess many
medicinal properties.7-16 It is traditionally used for a number of
aliments and is present in a wide range of herbal medicines,
nutraceuticals and food supplements.17 It has been reported that G.
glabra display cancer chemopreventive activity via induction of
nuclear factor (erythroid-derived 2)-like factor
2
(Nrf2).18-19
Furthermore, the glycyrrhizic acid (2), a constituent of G. glabra is
reported to provide protection against cisplatin-induced genotoxicity
and nephrotoxicity.20 Another constituent, isoliquiritigenin possesses
chemopreventive activity through induction of a phase II enzyme,
quinone reductase-1, in murine hepatoma cells.21 Licorice extracts
are also reported to prevent the Helicobacter pylori-initiated, salt
diet-promoted gastric tumorigenesis.22 Recently, van Breemen's
group23 have investigated the inhibitory effects of licorice and its 14
# contributed equally to this work
*Corresponding author. E-mail: sbharate@iiim.ac.in (SBB), bchaudhuri@dmu.ac.in (BC)

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Bioorganic & Medicinal Chemistry Letters
Further, the CYP inhibitory activity was evaluated in live human
cells. Compound 4 (quercetin) was found to be the most potent
CYP1B1 inhibitor with IC50 value of 2.2 µM. Glabrol (6) was found
to be a moderate inhibitor of CYP1B1 showing IC50 value of 15 µM.
Table 1. CYP1A1 and CYP1B1 inhibition by G. glabra extracts in
Sacchrosomes and in live cellsa
Sacchrosomes
IC50 (µg/mL)
HEK-293 cells
overexpressing CYP1A1/1B1
IC50 (µg/mL)
Extract
CYP2 and CYP3 family of enzymes are primarily involved in drug-
drug interactions; therefore, the effect of these two compounds on
CYP2D6 and CYP3A4 was also assessed. Results are shown in
Table 3. Both compounds do not show any effect on these two
enzymes, indicating their selectivity towards CYP1 family of
enzymes and thus would be expected to be free from potential drug-
drug interactions.
CYP1A1
CYP1B1
CYP1A1
16 1.2
20 1.6
CYP1B1
18 1.5
16 1.6
GG-A003
GG-A002
31
34
3
3
19 1.5
21 1.8
aAll values, presented in µg/mL concentrations, represent the mean and
standard deviations of three independent experiments.
The phytochemical investigation of extracts by routine silica column
chromatography using hexane to ethyl acetate to methanol gradient
resulted in isolation of 12 compounds. Partially purified compounds
obtained from repeated silica column chromatography were further
purified by Sephadex LH20 using methanol as mobile phase (except
glycyrrhizin and glycyrrhetic acid). For isolation of glycyrrhizin, the
concentrated hydroalcoholic extract of G. glabra roots was
sequentially washed with DCM and cold acetone to remove low
molecular weight phenolics. By repeating this procedure, 80% pure
glycyrrhizin was obtained, which was crystallized in ethanol-water
(8:2) solvent. 18β-glycyrrhetic acid (2) was obtained from hydrolysis
of glycyrrhizin (1) by 5% hydrochloric acid. Glycyrrhizin (1),
glycyrrhetic acid (GA) (2), 4'-O-Me glabridin (3), quercetin (4), 3-
hydroxyglabrol (5), glabrol (6), glabridin (7), formononetin (8),
isoliquiritigenin (9), liquiritigenin (10), isoliquiritin apioside (11) and
medicarpin (12) were isolated (Figure 1). All isolated compounds
were characterized by comparison of 1H NMR and melting point
with reported values. Wherever required, 13C NMR and 2D NMR
data were also recorded.
Table 2. In-vitro CYP1A1/CYP1B1 inhibition by isolated compounds 1-12 in
SacchrosomesTM
Entry
% inhibition ( SD)a
in Sacchrosomes at 10 µM
CYP1A1
CYP1B1
1
2
3
39 1.5
11.4 0.4
29.6 1.1
31.5 1.2
31.4 1.1
67.2 2.5
36.8 1.4
10.8 0.3
22.3 0.8
19.2 0.5
11.4 0.3
27.5 0.9
97 1.1
10.5 0.3
-2.1 0.2
12.0 0.3
67.2 2.6
7.5 0.3
4
5
6
7
17.7 0.6
26.6 0.8
-1.3 0.2
3.1 0.2
38.2 1.4
-9.5 0.3
31.7 1.1
98 1.0
8
9
10
11
12
ANF
aAll % inhibition values represent the mean and standard deviations of three
independent experiments.
The screening results led to the identification of G. glabra extracts,
quercetin (4) and glabrol (6) as inhibitors of CYP1 family of
enzymes. To demonstrate their potential utility in therapeutics, the
effect of extracts and compounds was assessed in two assays: (a)
reversal of cisplatin resistance in breast cancer cells; and (b)
protection of human cells from benzopyrene B[a]P (a procarcinogen)
medicated toxicity.
All isolated compounds were tested for inhibition of CYP1A1 and
CYP1B1 in Sacchrosomes at 10 µM (Table 2). Results showed that
quercetin (4) is a potent inhibitor of CYP1B1 enzyme (67.2%
inhibition at 10 µM) and glabrol (6) is a promising inhibitor of
CYP1A1 enzyme (67.2% inhibition at 10 µM). Based on the
significant inhibition showed by these two compounds, their IC50
values were determined in Sacchrosomes and are shown in Table 3.
O
O
O
HO
HO
R
O
R
OH
O
O
O
H
O
H
OH
OH
O
O
H
H
HOOC
OH
O
HO
HO
H
H
HO
HO
O
HO
O
O
OH
OH
HOOC
O
OH
HO
HO
OH
1
2
3: R = Me
7: R = H
4
5: R = OH
6: R = H
HO
HO
O
O
OMe
OMe
HO
O
O
O
O
HO
OH
O
H
OH
HO
O
O
OH
HO
OH
HO
O
O
HO
O
OH
OH
8
9
10
11
12
Figure 1. Chemical constituents isolated from G. glabra roots.
Table 3. IC50 values for in-vitro cytochrome P450 enzymes inhibition by selected compounds in SacchrosomesTM and live cells
Entry
IC50 in µM
IC50 in µM
(HEK293 cells overexpressing respective CYP enzyme)
(Sacchrosomes)TM
CYP1A1
>20
17.6 1.4
CYP1B1
1.0 0.3
>20
CYP1A2
>20
>20
CYP3A4 CYP2D6
CYP1A1 CYP 1B1
CYP1A2
>20
>20
CYP3A4
>20
>20
CYP2D6
4
>20
>20
>10
>20
>20
>10
9.9 0.7
>20
2.2 0.3
15 1.4
>10
>20
>20
>10
6
ANF
0.01 0.002 0.05 0.01 0.03 0.01
>10
>10
>10

Table 4. EC50 values of cisplatin after treatment of CYP1B1-overexpressing MDA-MB-468 cells with cisplatin and a CYP1B1 inhibitora
3
Cell line
CYP1B1 substrateb
cisplatin,
EC50 (µM)
0.65 0.28
0.76 0.32
6.70 0.7
1.6 0.3
Extract/
CYP1B1 IC50 of extract/
compound (µM)
compound
–
–
–
–
–
MDA-MB-468:: –
cisplatin
cisplatin
cisplatin
cisplatin
cisplatin
cisplatin
cisplatin
cisplatin
MDA-MB-468::pcDNA3.1
MDA-MB-468::pcDNA3.1/CYP1B1
MDA-MB-468::pcDNA3.1/CYP1B1
MDA-MB-468::pcDNA3.1/CYP1B1
MDA-MB-468::pcDNA3.1/CYP1B1
MDA-MB-468::pcDNA3.1/CYP1B1
–
GG-A003
18 µg/ml
16 µg/ml
2.2 µM
15 µM
GG-A002
1.4 0.3
4
1.1 0.2
6
5.2 0.6
MDA-MB-468::pcDNA3.1/CYP1B1
ANF
>10 µM
5.1 0.6
a
The cells used were: (a) untransfected MDA-MB-468 cells (MDA-MB-468:: –), (b) MDA-MB-468 cells transfected with pcDNA3.1 (i.e. MDA-MB-468::
pcDNA3.1), the basic plasmid which does not contain a gene insert, and (c) MDA-MB-468 cells transfected with pcDNA3.1/hCYP1B1 (i.e. MDA-MB-468::
pcDNA3.1/hCYP1B1), a plasmid encoding the human CYP1B1 gene. b range of concentrations of cisplatin (0.03 µM – 30 µM) were used, in the presence of 3 x
IC50 values of GG-A003 and GG-A002 extracts and compound 4 (as determined in the human cell assay where cells were grown in suspension), whereas 6 and
ANF were used at 20 µM concentrations. Thus, the test concentrations of GG-A003, GG-A002, compound 4, 6, and ANF were 54 µg/mL, 48 µg/mL, 6.6 µM,
20 µM and 20 µM, respectively. Adherent MDA-MB-468 cells, maintained in RPMI-1640 medium without phenol red with 10% fetal calf serum and 2 mM
glutamine, were transfected with pcDNA3.1/hCYP1B1 (plasmid encoding the human CYP1B1 gene). All values, presented in µM concentrations, represent the
mean and standard deviations of three independent experiments.
The EC50 was restored to 1.6 and 1.4 µg/mL from 6.7 µM, which is
>90% reversal of resistance. Similar to the extracts, pure natural
product quercetin (4) also restored the cisplatin activity (EC50 = 1.1
µM). However, glabrol (6) could only marginally reverse this
resistance (Table 4).
Reversal of cisplatin-resistance in MDA-MB-468 cells. The
overexpression of CYP1B1 enzyme causes resistance to anticancer
drug cisplatin. MDA-MB-468 (ATCC, HTB-132) is a triple negative
breast cancer cell line. Triple-negative breast cancer (TNBC) is an
invasive carcinoma of the breast that lacks expression of (a) the
estrogen receptor (ER), (b) progesterone receptor (PR) and (c)
human epidermal growth factor receptor 2 (HER2). Drug resistance
is a fundamental problem in TNBC management, and is responsible
for most cases of treatment failure in patients with metastatic cancer.
Cisplatin resistant ovarian cancer A2780 cells have been reported to
overproduce CYP1B1.6 In analogy to this observation, it is likely
that cisplatin-resistant TNBC cells would also overexpress CYP1B1.
Hence, a plasmid bearing the human CYP1B1 gene was transfected
in MDA-MB-468 cells to mimic the situation that is likely to exist in
cisplatin-resistant TNBC cells. Cisplatin manifests its toxicity in
MDA-MB-468 cells that is transfected with an empty plasmid (that
contains no CYP1B1 gene), whereas the same cells transfected with a
plasmid encoding CYP1B1 gene is resistant (Table 4). The EC50 of
cisplatin was increased from 0.65 to 6.70 µM (10-fold decrease in
cisplatin’s activity) in CYP1B1-transfected MDA-MB-468 cells.
Then, we studied the ability of extracts and compounds possessing
CYP1B1 inhibitory activity, to overcome cisplatin resistance in
CYP1B1 overexpressing triple negative MDA-MB-468 cells. Both
extracts GG-A002 and GG-A003 were found to restore the cisplatin-
potency, as evidenced by the EC50 of cisplatin in extract treated cells.
Protection of human cells from B[a]P medicated toxicity. Aryl
hydrocarbon hydroxylase (CYP1A1) is involved in the metabolic
activation of aromatic hydrocarbons, e.g. CYP1A1 catalyses the
oxidation of B[a]P to form B[a]P-7,8-epoxide which further oxidizes
to B[a]P-7,8-dihydrodiol. With the help of epoxide hydrolase, B[a]P-
7,8-dihydrodiol gets converted to B[a]P-7,8-dihydrodiol 9-10,
epoxide which is a carcinogen. In this study, we took recombinant
HEK293 cells that contain a plasmid that encodes the human
CYP1A1 gene and cells without the CYP1A1 gene (i.e. untransfected
HEK293 cells). The B[a]P EC50 values for cell viability were 1.2
0.3 and 14 1.2 µM, respectively, in these two types of cells (Table
5). Both extracts of G. glabra completely rescued human cells from
B[a]P toxicity at 3 x IC50 concentration (Table 5). Compound 4 was
also able to overcome CYP1A1-mediated B[a]P toxicity in CYP1A1
over-expressing HEK293 cells, as the EC50 of B[a]P was decreased
from 1.2 to 8.8 µM (Table 5).
Molecular modeling of quercetin (4) and glabrol (6) with
CYP1B1. Flavonoids 4 and 6 showed inhibition of CYP1B1 and this
inhibition was selective over 3A4 and 2D6. To justify the observed
trend in potency and selectivity, molecular modeling studies were
Table 5. EC50 values of B[a]P after treatment of CYP1A1-overexpressing adherent HEK293 cells with B[a]P and a CYP1A1 inhibitor a
Cell line
CYP1A1 IC50 of extract /
compound (µM)
Extract/ compound
CYP1A1 substrateb
EC50 (µM) of B[a]P
HEK293:: –
–
–
B[a]P
B[a]P
B[a]P
B[a]P
B[a]P
B[a]P
B[a]P
B[a]P
14 1.2
HEK293::pcDNA3.1
–
–
13.2 0.9
1.2 0.3
8.65 0.8
10.25 1.0
8.8 0.6
2.3 0.7
3.2 0.4
HEK293::pcDNA3.1/CYP1A1
HEK293::pcDNA3.1/CYP1A1
HEK293::pcDNA3.1/CYP1A1
HEK293::pcDNA3.1/CYP1A1
HEK293::pcDNA3.1/CYP1A1
HEK293::pcDNA3.1/CYP1A1
–
–
GG-A003
16 µg/ml
20 µg/ml
9.9 µM
>20 µM
>10 µM
GG-A002
4
6
ANF
a
The cells used were: (a) untransfected HEK293 cells (HEK293:: –), (b) HEK293 cells transfected with pcDNA3.1 (i.e. HEK293:: pcDNA3.1), the basic
plasmid which does not contain a gene insert and (c) HEK293 cells transfected with pcDNA3.1/hCYP1A1 (i.e. HEK293:: pcDNA3.1/hCYP1A1), a plasmid
which encodes the human CYP1A1 gene. bA range of concentrations of B[a]P (0.05 µM – 100 µM) were used, in the presence of 3 x IC50 values of GG-A003
and GG-A002 extracts (as determined in the human cell assay where cells had been grown in suspension), whereas compounds 4, 6 and ANF (α-naphthoflavone)
were used at 20 µM concentrations. Adherent HEK293 cells were used for all plasmid transfection. All values, presented in µM concentrations, represent the
mean and standard deviations of three independent experiments.

4
Bioorganic & Medicinal Chemistry Letters
performed. Quercetin (4) was found to display overlapping
interactions exactly like alpha-napthoflavone. Quercetin showed π-π
interactions with Phe 134 and Phe 231. Further, it displayed H-
binding interactions with Asp 326 and Asn 265 residues of the
CYP1B1 binding pocket (Figure 2A). The overlay image of
quercetin with ANF in the binding cavity of CYP1B1 is shown in
supporting information (section S3). In case of glabrol, its terminal
hydroxyl group forms polar H-bond with the Asn 228 residue of F
helix and both phenyl ring forms hydrophobic π-π interactions with
C helix Phe134 and F helix Phe231 residue. The diprenylated rings
showed favorable van der Waals interactions with receptor.
However, despite of common interactions pattern, quercetin (4) and
glabrol (6) displayed difference in inhibition potency towards
CYP3A4 and CYP2D6 which is due to the difference in structural
architecture of these enzymes (i.e. shape and amino acid residues
that form edges of the cavity). In case of CYP2D6, they displayed
only π-π hydrophobic interactions with the Phe483 residue. While in
case of CYP3A4, glabrol interacts with Phe215 residue rather than
corresponding Phe231 residue of CYP1A1 in F helix due to the open
nature of the binding cavity.
Supporting information available. Experimental procedures and
spectral data scans. This material is available free of charge via the
internet at http://sciencedirect.com.
ACKNOWLEDGEMENTS
The work was supported by CSIR 12th FYP grant # BSC-0205 (SBB)
and HEIF funding (BC).
References
1
Smith, L.; Welham, K. J.; Watson, M. B.; Drew, P. J.; Lind, M.
J.; Cawkwell, L. Oncol Res 2007, 16, 497.
2
3
Tian, J.; Lin, Y.; Yu, J. Biomed Pharmacother 2017, 92, 919.
Xie, Q.; Wang, S.; Zhao, Y.; Zhang, Z.; Qin, C.; Yang, X.
Oncotarget 2017, 8, 22003.
4
5
McFadyen, M. C.; McLeod, H. L.; Jackson, F. C.; Melvin, W. T.;
Doehmer, J.; Murray, G. I. Biochem Pharmacol 2001, 62, 207.
Xie, S.; Tu, Z.; Xiong, J.; Kang, G.; Zhao, L.; Hu, W.; Tan, H.;
Tembo, K. M.; Ding, Q.; Deng, X.; Huang, J.; Zhang, Q. Oncol
Rep 2017, 37, 921.
6
Horley, N. J.; Beresford, K. J.; Chawla, T.; McCann, G. J.;
Ruparelia, K. C.; Gatchie, L.; Sonawane, V. R.; Williams, I. S.;
Tan, H. L.; Joshi, P.; Bharate, S. S.; Kumar, V.; Bharate, S. B.;
Chaudhuri, B. Eur J Med Chem 2017, 129, 159.
7
8
Vaya, J.; Belinky, P. A.; Aviram, M. Free Rad. Biol. Med. 1997,
23, 302.
Rackova, L.; Jancinova, V.; Petrikova, M.; Drabikova, K.; Nosal,
R.; Stefek, M.; Kostalova, D.; Pronayova, N.; Kovacova, M. Nat.
Prod. Res. 2007, 21, 1234.
Phe134
9
Wang, Z. Y.; Nixon, D. W. Nutrition and Cancer 2001, 39, 1.
Phe231
10 Sabahi, M.; Mansouri, S. H.; Ramezanian, M.; Gholam-
Hoseinian, A. Int. J. Crude. Drug. Res. 1987, 25, 72.
11 Christensen, S. B.; Ming, C.; Andersen, L.; Hjorne, U.; Olsen, C.
E.; Cornett, C.; Theander, T. G.; Kharazmi, A. Planta Med.
1994, 60, 121.
Heme
Asp326
Asn265
12 Amirghofran, Z. Iran. J. Immunol. 2010, 7, 65.
13 Kelly-Pieper, K.; Patil, P. S.; Busse, P.; Yang, N.; Sampson, H.;
Li, X.-M.; Wisnivesky, P. J.; Kattan, M. J. Altern. Complement.
Med. 2009, 15 735.
(A)
14 Dirican, E.; Turkez, H. Cytotechnology 2014, 66, 9.
15 Jo, E. H.; Hong, H. D.; Ahn, N. C.; Jung, J. W.; Yang, S. R.;
Park, J. S.; Kim, S. H.; Lee, Y. S.; Kang, K. S. J. Agric. Food.
Chem. 2004, 52, 1715.
Phe134
16 Jo, E.-H.; Kim, S.-H.; Ra, J.-C.; Kim, S.-R.; Cho, S.-D.; Jung, J.-
W.; Yang, S.-R.; Park, J.-S.; Hwang, J.-W.; Aruoma, O. I.; Kim,
T.-Y.; Lee, Y.-S.; Kang, K.-S. Cancer Lett. 2005, 230, 239.
17 Fiore, C.; Eisenhut, M.; Ragazzi, E.; Zanchin, G.; Armanini, D.
J. Ethnopharmacol. 2005, 99, 317.
Phe231
18 Basar, N.; Nahar, L.; Oridupa, O. A.; Ritchie, K. J.; Talukdar, A.
D.; Stafford, A.; Kushiev, H.; Kan, A.; Sarker, S. D. Phytochem
Anal 2016, 27, 233.
19 Gong, H.; Zhang, B. K.; Yan, M.; Fang, P. F.; Li, H. D.; Hu, C.
P.; Yang, Y.; Cao, P.; Jiang, P.; Fan, X. R. J. Ethnopharmacol
2015, 162, 134.
Heme
Asp326
Asn265
(B)
Figure 2. (A-B) Docked complex of compound 4 and 6 with CYP1B1,
respectively. Yellow dotted lines indicate H-bonding, blue dotted lines
indicates π-π interactions and orange dotted lines indicates van der Waals
interactions between ligand and receptor.
20 Arjumand, W.; Sultana, S. Life Sci 2011, 89, 422.
21 Cuendet, M.; Guo, J.; Luo, Y.; Chen, S.; Oteham, C. P.; Moon,
R. C.; van Breemen, R. B.; Marler, L. E.; Pezzuto, J. M. Cancer
Prev Res (Phila) 2010, 3, 221.
22 Park, J. M.; Park, S. H.; Hong, K. S.; Han, Y. M.; Jang, S. H.;
Kim, E. H.; Hahm, K. B. Helicobacter 2014, 19, 221.
23 Li, G.; Simmler, C.; Chen, L.; Nikolic, D.; Chen, S. N.; Pauli, G.
F.; van Breemen, R. B. Eur J Pharm Sci 2017, 109, 182.
In summary, we have identified that G. glabra possesses potent
ability to inhibit CYP1B1 and CYP1A1 enzymes, and it protects
cells from procarcinogens and overcomes cisplatin-resistance in
CYP1B1 over-expressing triple negative breast cancer cells MDA-
MB-468. Quercetin, a flavonoid isolated from this plant is also a
potent inhibitor of CYP1B1 and it effectively reverses the cisplatin
resistance in breast cancer cells. These results warrant further
exploration of G. glabra and quercetin as resistance reversal agents
in animal models.