Synthesis of trans-caffeate analogues and their bioactivities against HIV-1 integrase and cancer cell lines

Article abstract of DOI:10.1016/j.bmcl.2008.10.046

Forty caffeate analogues were synthesized via a convenient method starting from vanillin with moderate to good yields. The testing of biological activity of these compounds against HIV-1 integrase indicates that four compounds: bornyl caffeate, bornyl 2-nitrocaffeate, 5-nitrocaffeic acid and 5-nitrocaffeic acid phenethyl ester (5-nitroCAPE) possess a good HIV integrase inhibitory activity, IC₅₀ 19.9, 26.8, 25.0 and 13.5 μM, respectively. Twelve caffeate analogues were tested by MTT assay on growth of human hepatocellular carcinoma BEL-7404, human breast MCF-7 adenocarcinoma, human lung A549 adenocarcinoma and human gastric cancer BCG823 cell lines, respectively. And the best result is IC₅₀ 5.5 μM for CAPE against BEL-7404.

Full text of DOI:10.1016/j.bmcl.2008.10.046

Bioorganic & Medicinal Chemistry Letters 18 (2008) 6553–6557
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis of trans-caffeate analogues and their bioactivities against HIV-1
integrase and cancer cell lines
Chun-nian Xia a, Hai-bo Li b, Feng liu a, Wei-xiao Hu a,
*
a College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310032, PR China
b Nantong Center for Disease Control and Prevention, Jiangsu 226001, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Forty caffeate analogues were synthesized via a convenient method starting from vanillin with moderate
to good yields. The testing of biological activity of these compounds against HIV-1 integrase indicates
that four compounds: bornyl caffeate, bornyl 2-nitrocaffeate, 5-nitrocaffeic acid and 5-nitrocaffeic acid
phenethyl ester (5-nitroCAPE) possess a good HIV integrase inhibitory activity, IC50 19.9, 26.8, 25.0 and
Received 21 May 2008
Revised 22 September 2008
Accepted 10 October 2008
Available online 15 October 2008
13.5
lM, respectively. Twelve caffeate analogues were tested by MTT assay on growth of human hepato-
cellular carcinoma BEL-7404, human breast MCF-7 adenocarcinoma, human lung A549 adenocarcinoma
Keywords:
and human gastric cancer BCG823 cell lines, respectively. And the best result is IC50 5.5
against BEL-7404.
lM for CAPE
Caffeate analogues
HIV-1 integrase
Antitumor
Ó 2008 Elsevier Ltd. All rights reserved.
Some naturally occurring caffeates are widely distributed in
III-26 and III-40 possess a good HIV-1 integrase inhibitory activity.
In part of esterifiable site, aryl ring or multi-ring compound seemed
to be required because of all alkyl esters being inactive; replacement
of 3-hydroxyl groups with methyl ether, such as III-25 to III-22, III-
26 to III-23, and III-40 to III-37, resulted completely loss of potency
whether adding a third group to the mother phenyl ring or not. So
the presence of a catechol entity seems to be of importance.6a
Adding a third strong election-withdrawing group NO2 on 3, 4-
dihydroxyl pattern resulted in potential activity, such as com-
pound III-25, III-26 and III-40. These evidences would reveal that
analogues with resonance electron-drawing group decrease elec-
tion density to stabilize the corresponding conformers responsible
for the higher activity.
Unfortunately, although the lead compound CAPE (III-19) was
tested twice by the same ELISA method, it showed no activity
against HIV integrase, which was not consistent with the results
of the literature.6a These different results may be somewhat differ-
ent from the Burke’s method, and it need more work to identify.
The antitumor activities in vitro for these compounds were eval-
uated by the MTT method for BEL-7404, MCF-7, A549 and BCG823
cell lines. The results are summarized in Table 2. All compounds ex-
cept for III-23 and III-33 possessed potent activity. III-19 and III-37
possessed stronger BEL-7404 activities than positive control cis-
platin. On the MCF-7 examination, III-17 showed good anti-breast
tumor potency. III-39 showed good anti-lung cancer potency. But
on the BCG832 examination, activities of all twelve compounds
were not better than that of positive control. Comparing with the
anti-HIV-1 integrase activities, replacement of the OH group with
CH3O group, such as III-40 to III-37, the antitumor activities did
not lost. Adding NO2 group as a third group, such as III-19 to III-
plant kingdom.1 Most of them have bioactivities such as antibacte-
3
rial,2 antiviral,
anti-inflammatory,4 antiatherosclerotic,5 anti-
HIV,6 antitumor7 and so on. Epidemiological studies indicate that
a diet, rich in fruits and vegetables reduces cancer risk in humans,
suggesting that certain dietary constituents may be effective in
preventing cancer.8 Especially, caffeic acid phenethyl ester (CAPE)
has been identified as the major biologically active compounds.9
Encouraged by the aforementioned information and as a part of
our new drug discovery efforts, it was valuable to synthesize caff-
eate analogues and study the structure–activity relationship (SAR)
on caffeate analogues.
Caffeate analogues have been synthesized previously by methods
such as: acid-catalyzed esterification, alkylation of caffeic acid with
halohydrocarbons, esterification via acyl chlorides, coupling reaction
with DCC ascoupling agent, transesterificationandWittigreaction.10
Herein, we have developed a more convenient, one-pot method to
prepare the caffeate analogues with moderate to good yields shown
as Scheme 1. The synthesized forty compounds were summarized in
Table 1. In addition, all caffeate analogues are trans (E) configuration
confirmed by the 1H NMR spectra in that the coupling constants of
a-
H and b-H on doublebonds were 15.9–16.4 Hz.11 Furthermore, it was
confirmed caffeate analogues are trans (E) configuration by X-ray
analysis of compound III-26 (Fig. 1). 12
The anti-HIV integrase activities of caffeates were evaluated by
the Biotin-Avidin ELISA method. The results were summarized in Ta-
ble 1. From Table 1, it has been found that compound III-21, III-25,
* Corresponding author. Tel./fax: +86 57188320557.
E-mail address: huyang@mail.hz.zj.cn (W. Hu).
0960-894X/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2008.10.046

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C. Xia et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6553–6557
Table 1
Anti HIV-1 integrase activities of caffeate analogues (III)
Entry
ROH (I)
R1
X
Y
Inhibition of HIV-1 integrase IC50 (lM)
III-1
III-2
H
H
H
H
H
H
H
>100
>100
III-3
III-4
H
H
H
H
H
H
>100
>100
III-5
III-6
H
H
H
>100
H
H
H
H
H
H
H
H
H
>100
>100
>100
III-7
III-8
H
H
H
>100
III-9
III-10
H
H
H
H
H
H
H
H
H
>100
>100
>100
III-11
III-12
H
H
H
H
H
H
H
H
H
>100
>100
>100
III-13
III-14
III-15
III-16
III-17
H
H
H
H
H
H
>100
>100
H
H
H
>100
III-18
H
H
H
H
H
H
>100
>100
III-19
III-20
H
H
H
19.9
III-21
III-22
H
CH3
CH3
NO2
NO2
H
H
>100
>100
III-23
CH3
NO2
H
>100
III-24
III-25
III-26
H
H
H
NO2
NO2
H
H
26.8
25.0
H
NO2
H
H
H
>100
>100
III-27
III-28
H
CH3

C. Xia et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6553–6557
6555
Table 1 (continued)
Entry
ROH (I)
R1
X
Y
Inhibition of HIV-1 integrase IC50
>100
(lM)
III-29
H
CH3
Cl
H
CH3
Cl
H
>100
III-30
CH3
CH3
CH3
Cl
Br
Br
H
H
H
>100
>100
>100
III-31
III-32
H
III-33
CH3
Br
H
>100
III-34
III-35
III-36
H
CH3
CH3
H
H
NO2
NO2
>100
>100
III-37
CH3
H
NO2
>100
III-38
III-39
H
H
H
H
H
NO2
NO2
>100
>100
III-40
H
H
NO2
13.5
Scheme 1. The synthesis route of trans-caffeate analogues. (See above-mentioned references for further information).
26 and III-39, III-21 to III-40, the antitumor activities did not in-
crease much. 5-Br (III-23) or 5-NO2 (III-33) phenethyl ferulate
was completely inactive. Comparing with all anti-cancer data, the
indicate that in our case there is no evidence for direct correlation
between HIV-1 integrase and antitumor inhibition.
In summary, 40 caffeate analogues synthesized by the simple one-
pot method with moderate to good yields, were tested by Biotin-Avi-
best result is IC50 5.5 lM for CAPE against BEL-7404. These results

6556
C. Xia et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6553–6557
activity;inthe mother phenyl part, the catecholentity wasimportant,
andthereplacement of 3-OHbyCH3O groupwill lostactivity; the NO2
group was assign to the mother phenyl ring could increase the activ-
ity. Some of compounds were tested by MTT method for antitutor
activities. Most of them possessed antitumor activities. The best re-
sult is IC50 5.5 lM for CAPE against BEL-740. Considering the struc-
ture–activity relationship, the ring substitutions and ester groups in
the structure are probably important determinants for some potent
biological activities which are worth to research further.
Figure 1. The crystal structure of 5-NO2CAPE.
Acknowledgments
The authors are thankful for the National Centre for Drug
Screening, Shanghai, PR China, and Nantong Center for Disease
Control and Prevention, Jiangsu, PR China, to evaluate the HIV-1
dinELISAmethodfortheactivitiesagainstHIV-1integrase. It hasbeen
found there are four compounds possessing good activities. In part of
esterifiable site, aryl or multi-ring group seems important for the
Table 2
Antitumor activities of some caffeate analogues (III)
Entry
Compound
IC50 (lM)
BEL-7404
15.5
MCF-7
30.3
A549
89.3
BCG832
97.6
III-12
III-17
III-18
III-19
III-20
III-21
III-23
III-26
III-33
III-37
III-39
44.3
17.4
5.5
5.9
75.9
27.3
83.6
50.0
19.5
>300
11.4
>300
21.1
8.7
56.56
48.1
44.6
59.8
100.6
>300
22.9
>300
32.1
27.8
14.1
26.7
12.8
>300
>300
12.3
>300
62.3
28.8
58.1
28.2
>300
59.7
>300
6.6
10.2
III-40
28.7
23.8
40.7
29.5
52.9
32.3
116.6
6.4
Control
Cisplatin

C. Xia et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6553–6557
6557
21/c, Z = 4, Dc = 1.400 g/cm3,
l
(Mo-Ka) = 0.11 mmÀ1
,
9258 reflections
integrase and antitumor activities, respectively. We also acknowl-
edge the financial support by the Science and Technology Depart-
ment of Zhejiang Province (Grant No.2005C23022).
measured, 3509 unique (Rint = 0.026) which were used in all calculations.
Fine R1 = 0.043,
x
R(F2) = 0.124 (all data). Full crystallographic details of III-26
have been deposited at the Cambridge Crystallographic Data Center and
allocated the deposition number CCDC 673003.
13. Perea, R. A.; Fernhndez-Alvarez, E.; Nieto, O.; Piedrdita, F. J. J. Med. Chem. 1992,
35, 4584.
Supplementary data
14. Appendino, G.; Daddario, N.; Minassi, A.; Moriello, A. S.; Petrocellis, L. D.;
Marzo, V. D. J. Med. Chem. 2005, 48, 4663.
15. Thi, B. T. L.; Iiyama, K.; Stone, B. A. Phytochemistry 1996, 41, 1507.
16. Vallejos, G.; Fierro, A.; Rezende, M. C.; Sepulveda-Boza, S.; Reyes-Parada, M.
Bioorg. Med. Chem. 2005, 13, 4450.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.bmcl.2008.10.046.
17. General procedure:Preparation of caffeic acid3,4-Dihydroxybenzaldehyde
(9.0 g, 65 mmol), malonic acid (7.3 g, 70 mmol) were added to a mixture of
toluene (15 ml), pyridine (100 mmol) and aniline (0.7 ml). The solution was
stirred at refluxing temperature 2 h. When the mixture was cooled to room
temperature, yellow precipitation was filtrated, then washed with 50 ml 3 M
HCl solution and 50ml water twice, respectively. The crude product was
recrystallized from EtOH to give the light beige powder 5.2 g (44.2%). mp 197–
200 °C; (Lit.211–213 dec.) 18; IR mmax (KBr/cmÀ1): 3433, 3238, 1644, 1619,
References and notes
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12. Xia, C. N.; Hu W. X. Zhou W. Acta Crystallogr., Sect. E. 2007, 63, o4795. Crystal
data of III-26. C17H15NO6, M = 329.30, Monoclinic, a = 8.584 (2), b = 5.373 (1),
c = 33.904 (7) Å , b = 91.757(32)°, U = 1562.8 (3) Å3, T = 296 (2) K, space group P
1280, 1217; 1H NMR (DMSO-d6,
7.461(1H, d, J = 16.4 Hz, b-H), 7.03(1H, s, Ph-H), 7.02(1H, d, J = 7.6 Hz, Ph-H),
6.75(1H, d, J = 7.6 Hz, Ph-H),6.27(1H, d, J = 15.9 Hz, -H).Preparation of Caffeic
r): 12.02(1H, br s, COOH), 9.35(1H, br s, 2OH),
a
acid phenylethyl ester (CAPE)The Meldrum’s acid (3.6 g, 25 mmol) was added
into toluene (50 ml), and then added b-phenethanol (3.05 g, 25 mmol). The
mixture was heated and refluxed for 4 h. When the mixture was cooled to
room temperature, added 3,4-dihydroxybenzaldehyde (1.4 g, 10 mmol),
pyridine (2.5 ml) and piperidine (0.25 ml). The stirring continued at room
temperature 22 h, using TLC to trace the reaction until the reaction completely
finished. The solvents were distilled out in vacuum; the residue was dissolved
in diethyl ether (30 ml), washed with saturated solution of sodium bicarbonate
20 ml twice, then diluted hydrochloride 20 ml and distilled water 20 ml,
respectively. The ether phase was dried by anhydrous MgSO4 overnight. After
removal of the drier, the solvent was distilled out to get yellow crude solid. The
crude solid was recrystallized from a mixture of benzene and diethyl ether
(8:2) to afford pale white needle crystal CAPE 2.56 g (90.1%). mp 126–128 °C
(Lit. 128 °C)6a; IR mmax (KBr/cmÀ1): 3481, 3329, 1683, 1601, 1279, 1181; 1H
NMR (DMSO-d6,
H), 7.22–7.33 (m, 5H, 5Ph-H), 7.04 (d, 1H, J = 2.4Hz, Ph-H), 7.00 (dd,1H, J = 2.4,
8.0 Hz, Ph-H), 6.76 (d, 1H, J = 8.0 Hz, Ph-H), 6.23 (d, 1H, J = 15.9 Hz, -H), 4.32
r): 9.59 (s, 1H, OH), 9.13 (s, 1H, OH), 7.45 (d, 1H, J = 15.9 Hz, b-
a
(t, 2H, J = 14.0 Hz, CH2), 2.95 (t, 2H, J = 14.0 Hz, CH2); IEMS (70 eV): 284 (3%,
M+), 180 (100), 163 (61), 134 (34), 105 (50), 104 (66), 89 (53), 77 (49), 51 (33).
18. Chan, W. S.; Wen, P. C.; Chiang, H. C. Anticancer Res. 1995, 15, 703.