Synthesis and biological evaluation of allylated mono-carbonyl analogues of curcumin (MACs) as anti-cancer agents for cholangiocarcinoma

Article abstract of DOI:10.1016/j.bmcl.2016.10.080

A series of new allylated mono-carbonyl curcumin analogues (MACs) were designed and synthesized. In vitro cytotoxic activities of allylated MACs 6a–h together with previously reported analogues 4a–i and 7a–e, were tested against human cholangiocarcinoma cell lines including HUCCA, QBC-939 and RBE. Of all the compounds tested, 6c exhibited potent in vitro antiproliferative activity against the three tested cancer cell lines with IC₅₀values of 8.7, 9.3 and 8.9 μM, respectively. Cell cycle analysis showed that 6c inhibited cell proliferation due to G2/M arrest. Furthermore, mechanistic studies revealed that 6c dose-dependently increased the level of Bax and inhibited the expression of Bcl-2, to induce cancer cell apoptosis. Taken together, this work provides a novel series of anti-cancer candidates for the treatment of cholangiocarcinoma.

Full text of DOI:10.1016/j.bmcl.2016.10.080

Bioorganic & Medicinal Chemistry Letters xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis and biological evaluation of allylated mono-carbonyl
analogues of curcumin (MACs) as anti-cancer agents for
cholangiocarcinoma
Chenyu Qiu a,1, Yan Hu a,b,1, Ke Wu a, Ke Yang a, Nan Wang a, Yue Ma a, Heping Zhu a, Yi Zhang b,
Yunfang Zhou a,c, Chao Chen a,d, Shanshan Li a, Lili Fu a, Xiuhua Zhang b, , Zhiguo Liu a,
⇑
⇑
a Chemical Biology Research Center at School of Pharmaceutical Sciences, Wenzhou Medical University, 1210 University Town, Wenzhou, Zhejiang 325035, China
b The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
c The Sixth Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
d College of Life Sciences, Huzhou University, Huzhou, Zhejiang 313000, China
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of new allylated mono-carbonyl curcumin analogues (MACs) were designed and synthesized. In
vitro cytotoxic activities of allylated MACs 6a–h together with previously reported analogues 4a–i and
7a–e, were tested against human cholangiocarcinoma cell lines including HUCCA, QBC-939 and RBE.
Of all the compounds tested, 6c exhibited potent in vitro antiproliferative activity against the three tested
Received 15 August 2016
Revised 20 October 2016
Accepted 27 October 2016
Available online xxxx
cancer cell lines with IC50 values of 8.7, 9.3 and 8.9 lM, respectively. Cell cycle analysis showed that 6c
inhibited cell proliferation due to G2/M arrest. Furthermore, mechanistic studies revealed that 6c
dose-dependently increased the level of Bax and inhibited the expression of Bcl-2, to induce cancer cell
apoptosis. Taken together, this work provides a novel series of anti-cancer candidates for the treatment of
cholangiocarcinoma.
Keywords:
Mono-carbonyl curcumin analogues
Cholangiocarcinoma
Chemical stability
Drug design
Ó 2016 Published by Elsevier Ltd.
Cholangiocarcinoma (CCA) is the second most common primary
liver cancer after hepatocellular carcinoma in the world [1,2]. This
aggressive disease accounts for 15% of all primary hepatic malig-
nancies and continues to be a major public health issue worldwide.
During the past decade, we have seen a dramatic increase in the
incidence and mortality of CCA in western countries [3–5]. From
an anatomic point of view, CCA is currently classified as intrahep-
atic (IH-CCA) or extrahepatic (EH-CCA), with the latter being the
most common presentation [6]. Although surgical resection has
been considered the best treatment option for localized cholangio-
carcinoma, local recurrences of this cancer are very common, and
the five-year survival rate after attempted curative resection is
only 20–40% [7,8]. Hence, the development of novel therapeutic
agents has been a focus of researchers investigating treatments
for cholangiocarcinoma.
Curcumin, a natural product present in turmeric (Curcuma
Longa), has been shown to have important anti-inflammatory
[9,10], anti-tumor [11–13], and free radical-scavenging properties
[14]. In recent years, a large number of preclinical and clinical
studies have indicated that curcumin has potential therapeutic
value against various diseases, such as inflammatory bowel disease
[15], arthritis [16], pancreatitis, and chronic anterior uveitis
[17,18], as well as certain types of cancer [19,20]. However, high
metabolic instability, low bioavailability and rapid plasma
clearance significantly limit the clinical application of curcumin.
Available evidence suggests that the active methylene group and
b-diketone moiety in the structure of curcumin contributes to its
instability, fast metabolism and poor bioavailability [21–23].
In our previous study, a series of allylated mono-carbonyl
analogues of curcumin (MACs) was designed and synthesized by
displacing a b-diketone moiety with a single carbonyl group, and
by introducing an ally group at the B ring. These analogues
(Compounds 4a–i and 7a–e) were evaluated for anti-inflammatory
⇑
activity, and some exhibitd enhanced stability under
a
Corresponding authors at: Department of Pharmacy, The First Affiliated
Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
physiological condition and promising therapeutic efficacy for
acute lung injury (ALI) [24,25]. Accumulating evidence indicates
that curcumin has potential antiproliferative and proapoptotic
effects against many types of cancers, but the inhibitory effects
(X. Zhang).
E-mail addresses: wzzhangxiuhua@126.com (X. Zhang), lzgcnu@163.com
(Z. Liu).
1
These authors contribute equally to this work.
http://dx.doi.org/10.1016/j.bmcl.2016.10.080
0960-894X/Ó 2016 Published by Elsevier Ltd.
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2
C. Qiu et al. / Bioorganic & Medicinal Chemistry Letters xxx (2016) xxx–xxx
β-diketone
O
O
H3CO
HO
OCH3
OH
Curcumin
Structural
O
modification
A
R2
B
X
OH
R1
O
New allylated MACs (4a-i, 6a-h and 7a-e)
R'
n
OH
Allylated mono-carbonyl analogues
of curcumin (MACs)
Figure 1. Chemical structures of curcumin and structural design of allylated mono-carbonyl curcumin analogues (MACs) 4a–l, 6a–h and 7a–e.
of allylated MACs against cholangiocarcinoma cells remains to be
determined (Fig. 1).
6c exhibited the most potential anti-tumor activity with IC50 val-
ues of 8.7 against HUCCA, 9.3 against QBC-939 and
8.9 M against REB. These results suggest that allylated MACs
may have tremendous potential for the discovery of novel anti-
tumor agents.
In our previous reports, we identified symmetrical and asym-
metrical monocarbonyl analogues of curcumin (MACs) 4a–i and
7a–e [25]. In the present study, a novel series of allylated MACs
l
M
lM
As a part of our ongoing research in the development of new
anti-cancer drugs, we presented herein the next stage in the devel-
opment of allylated MACs as a novel molecular-targeted therapy
against cholangiocarcinoma. The majority of synthesized mole-
cules exhibited potential antiproliferative activity against a RBE
human cholangiocarcinoma cell line, and of all the compounds,
l
Table 1
Chemical structures of all allylated MACs
O
6
A
3
6'
B
β
β'
1'
R2
1
2
X
OH
R1
2'
Comp.
X
R1
R2
Comp.
X
R1
R2
4a
4b
4c
4d
4e
4f
4g
4h
4i
-N-
-N-
-N-
-N-
-N-
-N-
-N-
-N-
-H
-Me
-Et
3-allyl, 4-OH
3-allyl, 4-OH
3-allyl, 4-OH
3,4,6-OMe
3-allyl, 4-OH
3-allyl, 4-OH
3-allyl, 4-OH
3-allyl, 4-OH
6b
6c
6d
6e
6f
6g
6h
7a
7b
-O-
-S-
3-allyl, 4-OH
3-allyl, 4-OH
2,4,5-OMe
3,4-OMe
2,4,6-OMe
2,4-OMe
O-t-Bu
40-Methylpiperazine
40-Morpholine
-N-
-N-
-N-
-N-
-N-
-N-
-N-
-c-Pr
-c-Pr
-c-Pr
-c-Pr
-c-Pr
-c-Pr
-c-Pr
-Pr
-i-Pr
-c-Pr
-SO2-Pr
-Bz
O
HO
-CH-
OH
6a
-H-
3-allyl, 4-OH
7c
-N-
-c-Pr
40-Pyrrole
O
OTHP
OH
OH
allyl bromide
3,4-dihydro-2H-pyran
N,N-diethylaniline
200 oC, 5 h, 40.7%
acetone,K2CO3
PPTS, 8h, CH2Cl2
40 oC, 85.0%;
65 oC, 10 h, 86.2%
CHO
CHO
CHO
CHO
4
1
2
3
O
i) various benzaldehyde
EtOH, 20%NaOH,
O
O
X
rt, overnight,25-30%,
R1
R2
pyrrolidine,CH2Cl2
40 oC, 4 h, 40%;
X
OTHP
X
OH
ii) dilute HCl, EtOH
rt, 5h, 100%.
R1
R1
5a-h
6a-h
Scheme 1. General synthetic routes for 6a–h.
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C. Qiu et al. / Bioorganic & Medicinal Chemistry Letters xxx (2016) xxx–xxx
3
6a–h were also designed and synthesized, and their structures are
shown in Table 1. Our overall synthetic strategy is outlined in
Scheme 1. Allylation of 4-hydroxy benzaldehyde (1) provided
4-(allyloxy)benzaldehyde (2), which was subjected to the key
Claisen rearrangement to furnish 3-allyl-4-hydroxybenzaldehyde
(3). Protection of 3 with 3,4-dihydro-2H-pyran in the presence
of pyridinium p-toluenesulfonate gave 4-tetrahydropyranyloxy-
benzaldehyde (4) in quantitative yield. With 4 in hand, it was
treated with different cyclic ketones to provide ,b-unsaturated
a
ketones 5a–h under a basic condition. Aldol condensation of
ketones 5a–h and various benzaldehydes were given to corre-
sponding THP-protected intermediates, and those intermediates
were subjected to the acid hydrolysis to yield the desired ally-
lated MACs 6a–g, respectively.
Figure 2. MTT cell viability assay. (A and B) The effects of synthetic compounds and curcumin on the proliferation of human RBE cells and normal cells. Cell viability was
determined by MTT assay and the IC50 values of four active compounds 4f, 4i, 6b and 6c were calculated. (C and D) The effects of 6C on the proliferation of human
cholangiocarcinoma cell lines and normal cell lines. RBE, QBC-939, HUCCA, HL-7702 or HIBEC cells were incubated with increasing doses of 6C (0.625–20 lM) for 24 h,
respectively.
Figure 3. Ultraviolet–visible absorption spectra of curcumin (A), 4i (B), 6a (C), and 6c (D) in phosphate buffer (pH 7.4) containing 5% dimethyl sulfoxide.
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C. Qiu et al. / Bioorganic & Medicinal Chemistry Letters xxx (2016) xxx–xxx
In order to evaluate the biological effect of allylated MACs on
(6b), and dihydrothiopyran-4-one (6c) were more active than their
cyclopentanone (4i) counterpart. Again, exploring the N-substitu-
tion on the piperidin-4-one quickly revealed that a benzyl group
(4h) was favored for anti-cholangiocarcinoma potency. Further
SAR exploration at this position showed n-propyl (4d), isopropyl
(4e), and cyclopropyl (4f) were less potent on the induction of
apoptosis, and methyl (4b), ethyl (4c) and benzenesulfonic (4g)
substituents were not well tolerated. Additionally, a variety of
structural changes were explored, such as the structural symmetry
(7a–c), and ring substitution (6a–g), without improving upon the
anti-cancer activity.
Based on the MTT assays, compound 6c emerged as the most
effective compounds. We further investigated its cytotoxic effect
in cultured human cholangiocarcinoma and normal cells. As shown
in Fig. 2C, treatment of 6c for 24 h significantly induced cholangio-
carcinoma cell death in HUCCA, QBC939 and RBE with IC50 values
cancer cells, all the targeted compounds 4a–i, 6a–g and 7a–c
(Table 1) were screened for their anti-proliferative activity on
REB cholangiocarcinoma cell lines using MTT assay [26]. Com-
pounds that exhibited significant cytotoxicity were further evalu-
ated at different concentrations to obtain their IC50 values. Which
are shown in Fig. 2A. The majority of synthetic MACs were effective
in inhibiting the growth of RBE cells at a concentration of 20 lM.
Their inhibitory abilities were comparable to or more pronounced
than that of the control, curcumin. Among these tested com-
pounds, 4a, 4d–g, 4h, 6a–c and 6h were found to have a higher
inhibitory ability (less than 50% survival rate) upon 24 h of treat-
ment. In particular, the four compounds 4f, 4i, 6b and 6c showed
the strongest inhibitory potency against the growth of RBE cells
at 24 h, with IC50 of 14.4, 10.7, 15.0 and 8.1
respectively.
lM (Fig. 2B),
A close observation of the data showed that MACs containing
of 8.7, 9.3 and 8.9
lM, respectively. These IC50 values were signif-
piperidin-4-one (4a), cyclohexanone (6a), dihydropyran-4-one
icantly less than those of 5-Fluorouracil (5-FU), which is used in
Figure 4. 6c induces cycle arrest of human cholangiocarcinoma cells. (A and B) RBE, QBC-939 or HUCCA cells were incubated with curcumin (20
lM) or 6C at the indicated
concentrations for 24 h. The number of cells in G2/M phase was determined via flow cytometry. (C) Expression of G2/M cell cycle relative proteins P-53 and Cdc2 were
determined by western blot after treatment with 6C or curcumin (20 lM) for 24 h in three cell lines. GAPDH was used as internal control. The statistic data were presented as
mean S.E from three independent experiments. *p < 0.05, **p < 0.01; all versus DMSO group.
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C. Qiu et al. / Bioorganic & Medicinal Chemistry Letters xxx (2016) xxx–xxx
5
the treatment of cholangiocarcinoma in clinic (Fig. 2D). Mean-
while, it is clear from the IC50 values that compound 6c exhibited
a relatively low cytotoxicity toward the normal cell lines HL-
7702 (IC50 = 9.7 lM) and HIBEC (IC50 = 9.5 lM) (Fig. 2E), compared
to their anticancer potential against cholangiocarcinoma cell lines,
25 min at the maximum absorbance of 425 nm, this is consistent
with its instability and poor metabolic property. However,
allylated MACs 4i, 6b and 6c demonstrated almost complete
stability under the same condition (Fig. 3B–D). This result
indicated that these modified MACs are much more stable than
curcumin in vitro.
which justifies the role of 6c as an anti-cancer agents.
Curcumin has demonstrated potent anti-cancer and cancer pre-
vention activity in a variety of cancers. However, the clinical trans-
lation of curcumin has been significantly hampered due to its
instability and poor bioavailability. In our early publication, we
reported MACs 4f as one of the most stable compounds in a phos-
phate buffer (pH 7.4) [25]. Herein, we examined the stability of
active compounds 4i, 6b and 6c under the same experimental con-
ditions. As shown in Fig. 3A, 50% of the curcumin degraded within
To investigate the effect of 6c could be ascribed to a diverse
impact on cell cycle, we monitored cell cycle distribution by flow
cytometric analysis. Three cholangiocarcinoma cell lines (HUCCA,
QBC939 and RBE) were treated with 6c and curcumin for 24 h,
followed by cell cycle determination. The results in Fig. 4A and B
showed that compound 6c dose-dependently induced G2/M cell
cycle arrest in the three cancer cell lines, while no significant
G2/M arrest could be observed in the curcumin-treated group.
Figure 5. 6c induces apoptosis in human cholangiocarcinoma cells. (A) Induction of apoptosis in human cholangiocarcinoma cells was determined by flow cytometry after
treatment with 6c (5, 7.5 or 10 M) or curcumin (20 M) for 24 h. Similar results were obtained in three independent experiments. (B) The percentage of apoptotic cells in the
treatment groups was calculated (*p < 0.05, **p < 0.01). (C) Western blot analysis for expression of apoptosis-associated proteins in cells treated with or without 6C or
l
l
curcumin. Cells were treated with 6C at different concentrations as indicated or curcumin (20 lM) for 24 h, the cell lysates were processed for western blot analysis for
protein expression of Bcl-2, Bax, cleaved-PARP, and GAPDH used as a loading control.
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6
C. Qiu et al. / Bioorganic & Medicinal Chemistry Letters xxx (2016) xxx–xxx
The expression of tumor protein p53 and cell division cycle 2
Acknowledgments
(Cdc2) protein is crucial to cell cycle control [27], to further delin-
eate the underlying mechanism of 6c silencing on modulation of
the cell cycle, the expression of p53 and Cdc2 was analyzed with
western blot analysis. The results from Fig. 4C revealed that 5,
7.5 and 10 lM of compound 6c, induced a significant increase in
the expression of p53 and a decrease in expression of Cdc2 in a
This work was financially supported by the National Natural
Science Funding of China (21472142, 81402783), Natural Science
Funding of Zhejiang Province (LY17B020008, LY17H160050), Pub-
lic Welfare Science and Technology Project of Wenzhou
(Y20140736, Y20140738), the New-shoot Talents Program of Zhe-
jiang Province (2015R413075), the Science Funding for Student in
Wenzhou Medical University (wyx2016101001, wyx2016101026)
and Zhejiang Open Foundation of the Most Important Subjects.
concentration dependent manner. Consistent with the flow cytom-
etry outcomes, curcumin at 20 lM only showed slight effects on
the expression of these proteins. These results suggested that the
inhibition of cell proliferation by 6c was associated with the induc-
tion of the arrest of the G2/M phase.
Next, we measured the effects of compound 6c and curcumin
on the induction of cancer cell apoptosis in cholangiocarcinoma
cells. Three cholangiocarcinoma cell lines HUCCA, QBC939 and
A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2016.10.080.
REB were treated with 6c (5, 7.5, and 10
lM), curcumin (20 lM),
or DMSO (3 L) for 24 h, respectively. The cell apoptosis was deter-
l
References
mined by flow cytometry using Annexin V/propidium iodide (PI)
staining assay. As shown in Fig. 5A and B, active compound 6c
dose-dependently induced cell apoptosis in HUCCA, QBC939 and
[1] M.A. Ortner, Photodiagn. Photodyn. Ther. 1 (2004) 85.
[2] S. Rizvi, G.J. Gores, Gastroenterology 145 (2013) 1215.
[3] A.E. Sirica, Z. Zhang, G.H. Lai, T. Asano, X.N. Shen, D.J. Ward, A. Mahatme, J.L.
Dewitt, Hepatology 47 (2008) 1178.
[4] J. Choi, H.M. Ghoz, T. Peeraphatdit, E. Baichoo, B.D. Addissie, W.S. Harmsen, T.
M. Therneau, J.E. Olson, R. Chaiteerakij, L.R. Roberts, Hepatology 46 (2016)
1002.
RBE cells after 24 h of treatment. Notably, 6c at a dose of 10
induced a significantly higher apoptosis rate than that of curcumin
at a 20 M concentration.
lM
l
To further confirm the apoptotic effect of compound 6c and
study the mechanism of anti-cancer action, we measured the
expression of different pro-apoptotic and anti-apoptotic protein
markers in HUCCA, QBC939 and RBE cells after exposure to these
agents. As shown in Fig. 5C, treatment with compound 6c for
24 h dose-dependently increased the level of Bax and inhibited
the expression of Bcl-2 in three cholangiocarcinoma cells. Espe-
cially, the level of PARP cleavage, an apoptosis indicator, was
reduced significantly in a dose-dependent manner after treatment
of HUCCA cells. Therefore, the mechanistic studies suggested that
compound 6c induces apoptosis in HUCCA, QBC939 and RBE
cholangiocarcinoma cells through the mitochondrial pathway.
In summary, we previously reported the synthesis and anti-
inflammatory evaluation of a new class of allylated mono-carbonyl
curcumin analogues (MACs). In continuation of our research work,
in order to find a broad spectrum of biological MACs, we chose
twelve previously reported and eight newly synthesized MACs to
estimate their anti-cancer property by using MTT assay. Among
tested compounds, analogue 6c was found to display significant
[5] S. Zou, J. Li, H. Zhou, C. Frech, X. Jiang, J.S. Chu, X. Zhao, Y. Li, Q. Li, H. Wang, J.
Hu, G. Kong, M. Wu, C. Ding, N. Chen, H. Hu, Nat. Commun. 5 (2014) 5696.
[6] V. Cardinale, M.C. Bragazzi, G. Carpino, A. Torrice, A. Fraveto, R. Gentile, V.
Pasqualino, F. Melandro, C. Aliberti, C. Bastianelli, R. Brunelli, P.B. Berloco, E.
Gaudio, D. Alvaro, Hepatobiliary Surg. Nutr. 2 (2013) 272.
[7] J. Meza-Junco, A.J. Montano-Loza, M. Ma, W. Wong, M.B. Sawyer, V.G. Bain,
Can. J. Gastroenterol. 24 (2010) 52.
[8] S. Maximin, D.M. Ganeshan, A.K. Shanbhogue, M.K. Dighe, M.M. Yeh, O.
Kolokythas, P. Bhargava, N. Lalwani, Eur. J. Radiol. Open 1 (2014) 40.
[9] A.M. Katsori, M. Chatzopoulou, K. Dimas, C. Kontogiorgis, A. Patsilinakos, T.
Trangas, D. Hadjipavlou-Litina, Eur. J. Med. Chem. 46 (2011) 2722.
[10] S.C. Gupta, S. Prasad, J.H. Kim, S. Patchva, L.J. Webb, I.K. Priyadarsini, B.B.
Aggarwal, Nat. Prod. Rep. 28 (2011) 1937.
[11] Y. Li, T. Zhang, Cancer Lett. 346 (2014) 197.
[12] A. Kohyama, H. Yamakoshi, S. Hongo, N. Kanoh, H. Shibata, Y. Iwabuchi,
Molecules 20 (2015) 15374.
[13] N. Rainey, L. Motte, B.B. Aggarwal, P.X. Petit, Cell Death Dis. 6 (2015) e2003.
[14] T. Ak, I. Gülçin, Chem. Biol. Interact. 174 (2008) 27.
[15] J.S. Jurenka, Altern, Med. Rev. 14 (2009) 141.
[16] S.C. Gupta, S. Patchva, B.B. Aggarwal, AAPS J. 15 (2013) 195.
[17] N. Dhillon, B.B. Aggarwal, R.A. Newman, R.A. Wolff, A.B. Kunnumakkara, J.L.
Abbruzzese, C.S. Ng, V. Badmaev, R. Kurzrock, Clin. Cancer Res. 14 (2008) 4491.
[18] P. Allegri, A. Mastromarino, P. Neri, Clin. Ophthalmol. 4 (2010) 1201.
[19] B.B. Aggarwal, A. Kumar, A.C. Bharti, Anticancer Res. 23 (2003) 363.
[20] R. Wilken, M.S. Veena, M.B. Wang, E.S. Srivatsan, Mol. Cancer 10 (2011) 1.
[21] P. Anand, A.B. Kunnumakkara, R.A. Newman, B.B. Aggarwal, Mol. Pharm. 4
(2007) 807.
[22] Y.B. Pawar, B. Munjal, S. Arora, M. Karwa, G. Kohli, J.K. Paliwal, A.K. Bansal,
Pharmaceutics 4 (2012) 517.
[23] P. Dulbecco, V. Savarino, World J. Gastroenterol. 19 (2013) 9256.
[24] Z. Liu, L. Tang, P. Zou, Y. Zhang, Z. Wang, Q. Fang, L. Jiang, G. Chen, Z. Xu, H.
Zhang, G. Liang, Eur. J. Med. Chem. 74 (2014) 671.
cytotoxicity (8.7
lM in HUCCA cells, 9.3 lM in QBC939 cells, and
8.9 M in RBE cells) in cholangiocarcinoma cells and low toxicity
l
towards normal cells. Subsequent flow cytometry analysis (FCM)
indicated that exposure of these cholangiocarcinoma cell lines to
6c at different concentrations results in cell cycle arrest at the
G2/M phase. Mechanistic studies demonstrated that compound
6c induces apoptosis in cholangiocarcinoma cells through the
mitochondrial pathway. Therefore, compound 6c can be of thera-
peutic importance for the treatment of cholangiocarcinoma.
[25] H. Zhu, T. Xu, C. Qiu, B. Wu, Y. Zhang, L. Chen, Q. Xia, C. Li, B. Zhou, Z. Liu, G.
Liang, Eur. J. Med. Chem. 121 (2016) 181.
[26] W.H. Talib, A.M. Mahasneh, Sci. Pharm. 78 (2010) 33.
[27] B. Pucci, M. Kasten, A. Giordano, Neoplasia 2 (2000) 291.
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