Design and synthesis of 2-(3-alkylaminophenyl)-6-(pyrrolidin-1-yl)quinolin- 4-ones as potent antitumor agents

Article abstract of DOI:10.1016/j.bmcl.2012.11.105

2-(3-Alkylaminophenyl)-6-(pyrrolidin-1-yl)quinolin-4-ones 1-3 were synthesized and screened for anti-proliferative activity against three human cancer cell lines, as well as the normal cell line Detroit 551. All of the synthesized target compounds 1-3 dem

Full text of DOI:10.1016/j.bmcl.2012.11.105

Bioorganic & Medicinal Chemistry Letters 23 (2013) 699–701
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Bioorganic & Medicinal Chemistry Letters
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Design and synthesis of 2-(3-alkylaminophenyl)-6-(pyrrolidin-1-yl)quinolin-4-
ones as potent antitumor agents
Shih-Ming Huang a, Yung-Yi Cheng a, Ming-Hua Chen a, Chi-Hung Huang b,c, Li-Jiau Huang a, Mei-Hua Hsu a,
d,e,
Sheng-Chu Kuo a,d, , Kuo-Hsiung Lee
⇑
⇑
a Graduate Institute of Pharmaceutical Chemistry, China Medical University, Taichung 404, Taiwan
b Graduate School of Biotechnology, Hung Kuang University, Taichung 433, Taiwan
c Taiwan Advance Biopharm, Inc., 12F, No. 25, Lane 169, Kangning Street, Xizhi City, Taipei 221, Taiwan
d Chinese Medicine Research and Development Center, China Medical University Hospital, Taichung 404, Taiwan
e Natural Products Research Laboratories, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
2-(3-Alkylaminophenyl)-6-(pyrrolidin-1-yl)quinolin-4-ones 1–3 were synthesized and screened for anti-
proliferative activity against three human cancer cell lines, as well as the normal cell line Detroit 551. All
of the synthesized target compounds 1–3 demonstrated potent cytotoxic activity against the cancer cell
lines, but weak inhibitory activity toward the normal cell line. 2-(3-Methyl aminophenyl)-6-(pyrrolidin-
1-yl)quinolin-4-one (1), one of the potent compounds in vitro, was also tested in an in vivo Hep3B xeno-
graft nude mice model, and its significant anticancer activity was reconfirmed. Therefore, compound 1
merits further investigation as an antitumor clinical trial candidate and potential anticancer agent.
Ó 2012 Elsevier Ltd. All rights reserved.
Received 28 September 2012
Revised 21 November 2012
Accepted 26 November 2012
Available online 5 December 2012
Keywords:
2-(3-Alkylaminophenyl)-6-(pyrrolidin-1-
yl)quinolin-4-ones
Anticancer activity
In our continuing effort to develop novel anticancer agents dur-
ing the last decade, we have synthesized various derivatives of 2-
phenylquinolin-4-ones (PQs),1–4 tetrahydro-2-phenylquinolin-4-
ones (THPQs)5 and 2-phenylquinazolin-4-ones (QZs),6,7, as sum-
marized in Chart 1. These compounds were evaluated for in vitro
anticancer activity, and structure–activity relationship (SAR) corre-
lations were established. Based on this work, we have identified a
subset of compounds with potential for further development. From
the SAR, we found that the incorporation of a 6-pyrrolidinyl group
on certain PQ, THPQ and QZ compounds, for example, 2-(3-
methoxyphenyl)-6-(pyrrolidin-1-yl)quinolin-4-one (PQ1),3 2-(3-
methoxyphenyl)-6-(pyrrolidin-1-yl)tetrahydroquinolin-4-one
(THPQ1)5 and 2-(3-methoxyphenyl)-6-(pyrrolidin-1-yl)qunazolin-
4-one (OZ1)7 (shown in Chart 1), resulted in enhanced anti-prolif-
erative potency compared with than their corresponding analogs,
namely, PQ2–5, THPQ2 and QZ2–6. Among these 6-pyrrolidinyl
derivatives, the most potent compound, PQ1, was evaluated
against the USNCI-60 human cell line panel, where it exhibited
GI50 values in the nanomolar or sub-nanomolar level with an aver-
age logGI50 value of À8.72.
PQ, THPQ and QZ compounds. Undoubtedly, further investigation
of the anticancer activity of these pyrrolidinyl derivatives is war-
ranted. More recently, the mechanism of action of compound 1 to-
ward HL-60 leukemia cell line has been proposed in our separate
report.8 In this Letter, we focused on its anticancer activity against
hepatocellular carcinoma cell lines (HCC) instead. Hence, a series of
new derivatives of compound 1 were synthesized, and evaluated
for in vitro and in vivo anticancer activity in order to identify
new anticancer drug candidates with potential for further
development.
The target compounds 1–3 were synthesized according to our
previously reported method for PQs (Scheme 1). Initially, com-
pound 4 underwent a condensation reaction with 5 to afford the
amide intermediate 6, which was subjected to catalytic hydrogena-
tion to give the amide intermediate 7, which was N-alkylated sep-
arately with methyl iodide or ethyl iodide to yield the
corresponding mono-alkylamino derivatives 8, 10 or di-alkylamino
derivatives 9. Compounds 8–10 were further cyclized in 1,4-diox-
ane, in the presence of NaOH, to give the corresponding target
compounds 1–3.
Based on the above findings, we believe that the 6-pyrrolidinyl
group plays a critical role in potentiating the anticancer activity of
The above synthesized target compounds 1–3 were evaluated
for anti-proliferative activity against HL-60, Hep3B and H460 can-
cer lines, as well as the Detroit 551 normal human cell line. From
the results in Table 1, all of the tested target compounds 1–3 exhib-
ited significant anti-proliferative activity against HL-60, Hep3B and
H460 cells, but weak inhibitory activity toward the normal cell line
Detroit 551.
⇑
Corresponding authors. Tel: +886 4 2203 0760; fax: +886 4 2208 3362 (S.-C.
Kuo), Tel.: +1 919 962 0066; fax: +1 919 966 3893 (K.-H. Lee).
E-mail addresses: sckuo@mail.cmu.edu.tw (S.-C. Kuo), khlee@unc.edu (K.-H.
Lee).
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.11.105

700
S.-M. Huang et al. / Bioorg. Med. Chem. Lett. 23 (2013) 699–701
Table 1
O
O
O
R
R
R
IC50
(l
M) values from in vitro cytotoxicity testing of 1–3
NH
R'
R'
R'
N
H
N
N
H
O
N
R1
N
PQ
THPQ
QZ
R2
N
H
1 - 3
Compounds
PQ1 R6
=
N
O
R6
R6
R6
R6
=
=
PQ2
PQ3
PQ4
N(CH3)2
OCH3
R1
R2
IC50 (lM)
a
N
H
Compd
N
N
O
HL-60b
Hep3Bb
H460b
Detroit 551b
PQ1 ~ PQ5
=
=
N CH3
1
2
3
H
H
CH3
CH3
CH2CH3
CH3
0.006
0.005
0.005
0.021
0.020
0.015
0.035
0.020
0.013
>10
>10
>1
PQ5 R6
-OCH3
a
Data are presented as IC50 (lM) for each cell line; the concentration of com-
O
pound that caused a 50% proliferation–inhibitory effect after 2 days incubation.
R6
b
Cell lines include human promyelocytic leukemia (HL-60), human hepatoma
(Hep3B), human lung cancer (H460), and embryonic skin fibroblast cell line (Detroit
551).
R6
R6
=
=
N
THPQ1
THPQ2
OCH3
N
H
H
THPQ1 ~ THPQ2
In fact, compounds 1–3, with methylamino, ethylamino, and
dimethylamino groups in the 3-position, demonstrated the equiv-
alent potency against the Hep3B HCC cell line. 2-(3-Methylamin-
ophenyl)-6-(pyrrolidin-1-yl)quinolin-4-one (1), one of the these
potent compounds, was selected for evaluation of in vivo antitu-
mor activity. Compound 1 was evaluated against a Hep3B xeno-
graft nude mice model, and the results were summarized in
Figures 1. As indicated in Figure 1A, at dosages of 5, 10 and
20 mg/kg/day (ip), compound 1 demonstrated dose- and time-
dependent inhibition of Hep3B tumor growth. For instance, at
the 20 mg/kg/day dosage, the inhibition rate for tumor growth
QZ1 R6
=
N
R6
R6
=
=
O
QZ2
QZ3
QZ4
QZ5
QZ6
N(CH3)2
N
R6
NH
N
OCH3
R6
R6
=
=
N
N
CH3
QZ1 ~ QZ6
O
R6
=
-OCH3
was about 70% (calculated as 1-DT/DC). Meanwhile, as shown in
Figure 1C, no significant variation of mean body weight of Hep3B
Chart 1. .
O
O2N
Cl
O
O
O
N
N
N
H2, Pd/C
5
NH
NH
CH2Cl2
NH2
Et3N/THF
NO2
NH2
4
O
O
6
7
CH3I
CH3CH2I
DMF
O
O
N
N
NaOH
1,4-Dioxane
NH
R
N
H
R
O
1, 2, 3
8-10
1: R= NHCH3
8
: R= NHCH3
2
: R= NHCH2CH3
9: R= NHCH2CH3
3: R= N(CH3)2
10
: R= N(CH3)2
Scheme 1. Synthesis of 2-(3-alkylaminophenyl)-6-(pyrrolidin-1-yl)quinolin-4-ones (1–3).

S.-M. Huang et al. / Bioorg. Med. Chem. Lett. 23 (2013) 699–701
701
Figure 1A. Mean tumor volume–time profiles in Hep3B xenograft nude mice
(n = 11) following ip dosing of 1 at 5, 10, and 20 mg/kg 5 days per week for 4
consecutive weeks. Dosing was started after the tumor had grown to 100 mm3
(early stage).
Figure 1C. Mean body weight–time profiles in Hep3B xenograft nude mice (n = 11)
following ip dosing of 1 at 5, 10, and 20 mg/kg 5 days per week for 4 consecutive
weeks. Dosing was started after the tumor had grown to 100 mm3 (early stage).
Acknowledgments
The investigation was supported by research Grants from the
National Science Council of the Republic of China awarded to S.-
C.K. (NSC 101-2325-B-039-005). This study also was supported
by Taiwan Department of Health, China Medical University Hospi-
tal Cancer Research Center of Excellence (DOH101-TD-C-111-005).
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2012.
11.105.
References and notes
1. Kuo, S. C.; Lee, H. Z.; Juang, J. P.; Lin, Y. T.; Wu, T. S.; Chang, J. J.; Lednicer, D.;
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Figure 1B. Mean tumor weight–time profiles in Hep3B xenograft nude mice
(n = 11) following ip dosing of 1 at 5, 10, and 20 mg/kg 5 days per week for 4
consecutive weeks. Dosing was started after the tumor had grown to 100 mm3
(early stage).
4. Lai, Y. Y.; Huang, L. J.; Lee, K. H.; Xiao, Z.; Bastow, K. F.; Yamori, T.; Kuo, S. C.
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xenograft nude mice was observed between the control and com-
pound 1-treated group over 4 weeks. In brief, our results suggested
that 1 efficiently inhibited the growth of Hep3B tumor, at 10 and
20 mg/kg/day dosages, without causing significant toxicity.
Compound 1 exhibited potent anti-proliferative activity against
several human cancer cell lines, and significant inhibitory activity
against tumor growth of Hep3B in vivo. Therefore, we recommend
1 for further development as an anticancer drug candidate.