Synthesis of (-)-arctigenin derivatives and their anticancer activity

Article abstract of DOI:10.1080/14786419.2010.541874

The natural dibenzylbutyrolactone type lignanolide (-)-arctigenin, which was prepared from fructus arctii, showed obvious anticancer activity. The synthesis of four new (-)-arctigenin derivatives and their anticancer bioactivities were examined. The structures of the four new synthetic derivatives were elucidated.

Full text of DOI:10.1080/14786419.2010.541874

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Synthesis of (–)-arctigenin derivatives
and their anticancer activity
Chen Gui-Rong a , Cai Li-Ping b , Dou De-Qiang a , Kang Ting-Guo a
, Li Hong-Fu a , Li Fu-Rui a & Jiang Ning a
a College of pharmacy, Liaoning University of Traditional Chinese
Medicine, 77 Life one Road, DD port, Dalian 116600, China
b College of basic medical science, Liaoning University of
Traditional Chinese Medicine, 79 Chongshan East Road, Shenyang
110032, China
Published online: 26 Aug 2011.
To cite this article: Chen Gui-Rong , Cai Li-Ping , Dou De-Qiang , Kang Ting-Guo , Li Hong-
Fu , Li Fu-Rui & Jiang Ning (2012) Synthesis of (–)-arctigenin derivatives and their anticancer
activity, Natural Product Research: Formerly Natural Product Letters, 26:2, 177-181, DOI:
10.1080/14786419.2010.541874
To link to this article: http://dx.doi.org/10.1080/14786419.2010.541874
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Natural Product Research
Vol. 26, No. 2, January 2012, 177–181
SHORT COMMUNICATION
Synthesis of (–)-arctigenin derivatives and their anticancer activity
a
b
a
a
*
Chen Gui-Rong , Cai Li-Ping , Dou De-Qiang , Kang Ting-Guo ,
Li Hong-Fua, Li Fu-Ruia and Jiang Ninga
aCollege of pharmacy, Liaoning University of Traditional Chinese Medicine, 77 Life one
Road, DD port, Dalian 116600, China; bCollege of basic medical science, Liaoning University
of Traditional Chinese Medicine, 79 Chongshan East Road, Shenyang 110032, China
(Received 23 June 2010; final version received 5 November 2010)
The natural dibenzylbutyrolactone type lignanolide (–)-arctigenin, which
was prepared from fructus arctii, showed obvious anticancer activity. The
synthesis of four new (–)-arctigenin derivatives and their anticancer
bioactivities were examined. The structures of the four new synthetic
derivatives were elucidated.
Keywords: (–)-arctigenin; synthesis; synthetic derivatives; anticancer
bioactivity
1. Introduction
The natural dibenzylbutyrolactone type lignanolide (–)-arctigenin exhibited stronger
anticancer activity (Suresh, Jie, Surya, Yukiko, Yasuhiro, Shigetoshi, & Hiroyasu,
2006; Takasi, Konoshtma, Bardeesy, Sharpless, & Depinho, 2000) and could be used
as a lead precursor for further structure modification. The observation led us to
research the importance of lactone in anticancer activity and change the bioavail-
ability of (–)-arctigenin to find more safe and effective molecules. Herein,
(–)-arctigenin was used as a lead compound for further modification, we first
synthesised four new derivatives of (–)-arctigenin with methylamine, ethylamine,
butylamine and 2-chloro-ethylsulfonate sodium, and the reaction equations are
shown in Figures 1 and 2. Second, we elucidated the structures of the four new
derivatives and examined their anticancer bioactivity.
2. Results and discussion
Three new synthetic ammonoylsis derivatives of 1–3, were prepared by (–)-arctigenin
and three N-substituted primary amines stirred at room temperature (Figure 1).
The reactions were completed within 2–3 h for the three ammonoylsis derivatives
(Eckart et al., 1996). The new synthetic compounds were characterised by 1H-NMR,
13C-NMR and 2D-NMR spectra (Figure 3).
*Corresponding author. Email: doudeqiang2003@yahoo.com.cn
ISSN 1478–6419 print/ISSN 1478–6427 online
ß 2012 Taylor & Francis
http://dx.doi.org/10.1080/14786419.2010.541874
http://www.tandfonline.com

178
C. Gui-Rong et al.
O
O
O
H3CO
HO
H3CO
HO
NHR
OH
Room temperature
RNH2
aqueous solution
OCH3
OCH3
OCH3
OCH3
R=CH3
(-)-arctigenin
1- 3
R=C2H5
R=CH2CH2CH2CH3
O
O
O
1
7„
2„
5„
1„„„
2„
5„
7„
1„„„
7„
2„„„
NHCH2CH3
2„
5„
1„„„
NHCH2CH2CH2CH3
1
4„„„
2
H3CO
HO
H3CO
HO
H3CO
HO
NHCH3
1
2
2
3
CH2OH
4
CH2OH
4
3
CH2OH
7„„
3
7„„
7„„
4
2„„
2„„
2„„
5„„
5„„
OCH3
OCH3
5''
OCH3
OCH3
OCH3
OCH3
2
1
3
Figure 1. Synthetic route for ammonoylsis derivatives of 1–3.
O
O
OCH3
H3CO
HO
O
O
OCH2CH2SO3Na
NaOH
refluxed
ClCH2CH2SO3Na
H3CO
OCH3
OCH3
(-)-arctigenin
OCH3
4
Figure 2. Synthetic route for alkylation derivative of 4.
The new synthetic alkylation derivative of 4, was synthesised with the treatment
of (–)-arctigenin and 2-chloro-ethylsulfonate sodium (Figure 2). The reaction was
completed in 2 h for the alkylation derivative 4. Compound 4 was elucidated by
1H-NMR, 13C-NMR and 2D-NMR spectra (Figure 3).
All the synthetic derivatives were screened for anticancer activity by the five
different human cancer cells, HCT116 (human colon), MGC-803 (human gaster),
NCI-H460 (human lung), U251 (human astrocytes) and PANC-1 (human pancreas).
2.1. The structure elucidation of the four new synthetic derivatives
Compound 1 was obtained as white powder. The molecular formula of compound 1
was determined as C22H29NO6 by the spectroscopic data. Compared with the
molecular weight of (–)-arctigenin, the structure of 1 possesses an additional –
NHCH3 group. In the NMR spectra of 1, three methoxyls were observed by the

Natural Product Research
179
1
signal at ꢀ 3.80 (9H, s) in the H-NMR spectrum and their corresponding carbon
signals at ꢀ 56.4, 56.5, 56.6, respectively in the 13C-NMR spectrum according to the
1
HSQC spectrum of 1. Six aromatic protons emerged in the H-NMR spectrum at
ꢀ 6.67 (1H, d, J ¼ 1.9 Hz), 6.66 (1H, d, J ¼ 8.2 Hz), 6.58 (1H, dd, J ¼ 1.9, 8.2 Hz), 6.80
(1H, d, J ¼ 1.8 Hz), 6.86 (1H, d, J ¼ 8.2 Hz) and 6.77 (1H, dd, J ¼ 1.8, 8.2 Hz),
suggesting two ABX coupling systems in two phenyl groups. They coupled with the
13C-NMR signals of 1 at low field, the structure of 1 was deduced to contain two
1,2,4-trisubstituted phenyl fragments. The carbon signal at ꢀ 177.9 belonged to
carboxyl group. With the aid of HSQC, the proton signals at ꢀ 3.52 (1H, dd, J ¼ 11.3,
4.5 Hz), 3.58 (1H, dd, J ¼ 11.3, 5.0 Hz) correlated with the 13C-NMR signal at ꢀ 61.9,
revealed the presence of one –CH2OH group. The carbon signals at ꢀ 35.5, 37.2, 52.0
and 45.6 in the 13C-NMR spectrum and the proton signals at ꢀ 2.75 (1H, dd, J ¼ 6.2,
13.8 Hz), 2.70 (1H, dd, J ¼ 8.2, 13.8 Hz), 2.86 (1H, dd, J ¼ 6.0, 13.6 Hz), 2.82 (1H, dd,
1
J ¼ 9.8, 13.6 Hz), 2.56 (1H, m) and 1.98 (1H, m) in the H-NMR belonged to two
–CH2– and two –CH– fragments. Furthermore, the signal at ꢀ 2.59 (3H, s) due to
methyl in –NHCH3 showed long-range correlation with ꢀ 177.9 due to the
characteristic carbonyl carbon signal of C-1, suggesting that the –NHCH3 linked
to C-1. With the help of HMBC and HSQC spectra, the carbon and proton signals
were attributable as shown in Supplementary Table S1 (online only). Thus, the
structure was determined to be 2-(40-hydroxyl-30-methoxybenzyl)-3-(300,400-dimethoxy
benzyl)-4-hydroxy-N-methylbutanamide, and the NMR spectral data are shown in
Supplementary Table S1 (online only).
Compound 2 was afforded as white crystal. HR-ESI-MS gave its quasi molecular
ion peak at m/z 418.2252 [M þ H]þ (calcd 418.2230), indicating that the molecular
formula of 2 was confirmed as C23H31NO6. Compared with the molecular weight of
(–)-arctigenin, the structure of 2 contains an additional –NHCH2CH3 group. The
proton signals at ꢀ 3.06 (1H, qd, J ¼ 7.3, 16.7 Hz), 3.09 (1H, qd, J ¼ 7.3, 16.7 Hz) in
the 1H-NMR spectrum due to methylene in –NHCH2CH3 showed long-range
correlation with ꢀ 178.0 due to the characteristic carbonyl carbon signal of C-1,
indicating the –NHCH2CH3 linked to C-1. By comparing the spectral data with
1
those of 1, the complete molecule of 2 was established by H-NMR, 13C-NMR,
HSQC and HMBC experiments, whose structure was almost identical to that of 1.
Therefore, the structure of 2 was determined to be 2-(40-Hydroxyl-30-methoxy
benzyl)-3-(300, 400-dimethoxy benzyl)-4-hydroxy-N-ethylbutanamide, and the NMR
spectroscopic data are shown in Supplementary Table S1 (online only).
Compound 3 was afforded as white power. HR-ESI-MS gave its quasi molecular
ion peak at m/z 446.2547 [M þ H]þ, (calcd 446.2564), indicating that the molecular
formula of 3 was confirmed as C25H35NO6. The structure of 3 contains an additional
–NHCH2CH2CH2CH3 group compared with the molecular weight of (–)-arctigenin,
1
The proton signals at ꢀ 2.98 (1H, m), 3.10 (1H, m) in the H-NMR spectrum due to
methylene in –NHCH2CH2CH2CH3 showed long-range correlation with
ꢀ
177.1 due to the characteristic carbonyl carbon signal of C-1, indicating that the
–NHCH2CH2CH2CH3 linked to C-1. By comparing the spectroscopic data with that
1
of 1 and 2, the complete molecule of 3 was established by H-NMR, 13C-NMR,
HSQC and HMBC experiments, whose structure was almost identical to those of 1
and 2. Therefore, the structure of 3 was determined to be 2-(40-Hydroxyl-30-
methoxybenzyl)-3-(300, 400-dimethoxy benzyl)-4-hydroxy-N-butylbutanamide, and the
NMR spectroscopic data are shown in Supplementary Table S1 (online only).

180
C. Gui-Rong et al.
Table 1. The IC50 of compound 1, 2, 3, 4 and (–)-arctigenin.
Compounds
Unit
HCT116
MGC-802
NCI-H460
U251
PANC-1
(–)-arctigenin
Compound 1
Compound 2
Compound 3
Compound 4
mmol L–1
mmol L–1
mmol L–1
mmol L–1
mmol L–1
4.99
4200
100
4200
39.1
4200
4200
200
130.05
4200
4200
4200
4200
4200
168.15
4200
4200
4200
4200
4200
19.51
4200
4200
66.67
60.24
Figure 3. HMBC correlations of compounds 1–4.
Compound 4 was afforded as yellow powder. ESI-MS gave its quasi molecular
ion peak at m/z þ Na 547.1 [m/z þ Na]þ, showing that the molecular weight is 502.1
(calcd 502.1). The molecular formula of compound 4 was determined as
C23H27NaO9S by the quasi molecular ion peak at m/z þ Na 547.1 [m/z þ Na]þ in
the ESI-MS, as well as from its NMR spectroscopic data. The structure of 4
possesses an additional –CH2CH2SO3Na group compared to the molecular weight of
(–)-arctigenin. With the aid of HSQC, the proton signals at ꢀ 4.37 (2H, t, J ¼ 7.3 Hz),
1
3.31 (2H, t, J ¼ 7.3 Hz) in the H-NMR spectrum and the carbon signals at ꢀ 66.3,
51.9 in the 13C-NMR spectrum showed that the molecule of 4 contained
–OCH2CH2– group. With the help of HMBC, the proton signals at ꢀ 4.37
1
(2H, t, J ¼ 7.3 Hz) in the H-NMR spectrum due to the methylene in –OCH2CH2–
showed long-range correlation with ꢀ 148.1 due to the characteristic aromatic carbon
signal of C-40, indicating the –OCH2CH2– linked to C-40. The complete molecule of 4
was established by 1H-NMR, 13C-NMR, HSQC and HMBC experiments. Therefore,
the structure of 4 was determined to be (300, 400-dimethoxybenzyl)-3-(40-ethyl
sulfonate sodium-30-methoxybenzyl)-dihydrofuran-2(3H)-one, and the NMR spec-
tral data are shown in Supplementary Table S1 (online only).
2.1.1. The screen for anticancer bioactivity of (–)-arctigenin and new synthetic
derivatives
The anticancer bioactivities of 1–4 and (–)-arctigenin were determined (Qiu et al.,
2009). Anticancer assay was performed by five different human cancer cells, HCT116
(human colon), MGC-803 (human gaster), NCI-H460 (human lung), U251 (human
astrocytes) and PANC-1 (human pancreas). The IC50 of 1–4 and (–)-arctigenin
(200 mmol L–1) for the five cell lines were described as Table 1. From the Table 1,
results indicated that 1 and 2 showed weak cytotoxicity, 3 and 4 displayed moderate
cytotoxicity.

Natural Product Research
181
3. Conclusion
As (–)-arctigenin showed strong anticancer activity, (–)-arctigenin was used to be a
lead compound for further modification to find better anticancer bioactivity
molecules. The synthetic derivatives of 1–4 were obtained with the treatment of
amines and 2-chloro-ethylsulfonate sodium separately. 1–3 were ammonoylsis
derivatives and 4 was alkylation derivative. With the aid of spectroscopic data, the
structures of 1–4 were elucidated. The anticancer bioactivity of 1–4 and
(–)-arctigenin were tested by five different human cancer cells. The results indicated
that the anticancer bioactivity of 1–4 was weaker than that of (–)-arctigenin. It can
come to the conclusion that the lactone ring and the phenolic hydroxyl affected the
anticancer bioactivity.
Supplementary material
Experimental details relating to this paper are available online, alongside Table S1.
Acknowledgements
Thanks are due for the funding of the National Eleventh-five-year Plan in R&D of Important
New Medicine (Grant No. 2009ZX09103-423) and Supporting Plan Project for Excellent
Talents of Liaoning Provincial Education Department (Grant No. 2008RC34).
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