Selective synthesis and biological activity of triazine-porphyrins as potential anti-cancer agents

Article abstract of DOI:10.1142/S1088424610001805

Ten new triazine-porphyrin derivatives were synthesized using a simple one-pot procedure from the reaction of tetraphenylporphyrin bearing a hydroxyl group with 2,4,6-trichloro-1,3,5-triazine, and then with amines or alcohols. The structures of the products were characterized by ¹H NMR, LC/MS, UV-vis and elemental analysis. The cytotoxic activity of the triazine-porphyrin derivatives was evaluated in vitro against MCF-7 cell. All new compounds showed similar activity against MCF-7 cells in the absence of light when compared to 5-fluorouracil and hematoporphyrin.

Full text of DOI:10.1142/S1088424610001805

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2010; 14: 123–127
DOI: 10.1142/S1088424610001805
Published at http://www.worldscinet.com/jpp/
Selective synthesis and biological activity of
triazine-porphyrins as potential anti-cancer agents
Shen-Chu Xiao, Chao-Zhou Liu, Wu-Kun Liu, Wen-Zhong Xie, Wei-Ying Lin,
◊
Guo-Fang Jiang and Can-Cheng Guo*
College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China
Received 7 December 2008
Accepted 20 February 2009
ABSTRACT: Ten new triazine-porphyrin derivatives were synthesized using a simple one-pot procedure
from the reaction of tetraphenylporphyrin bearing a hydroxyl group with 2,4,6-trichloro-1,3,5-triazine,
1
and then with amines or alcohols. The structures of the products were characterized by H NMR, LC/
MS, UV-vis and elemental analysis. The cytotoxic activity of the triazine-porphyrin derivatives was
evaluated in vitro against MCF-7 cell. All new compounds showed similar activity against MCF-7 cells
in the absence of light when compared to 5-fluorouracil and hematoporphyrin.
KEYWORDS: triazine, synthesis, biological evaluation.
activity [8], VLA-4 (integrin very late antigen-4) antago-
INTRODUCTION
nism [9], estrogen receptor modulation [10], and cyto-
In the past few decades, the selective affinity of por-
toxic activity [11]. Some triazine derivatives such as
phyrins for cancer cells, which results in porphyrin and
hexamethylmelamine were developed as an effective
related compounds effectively accumulating within
agent against breast, lung, and ovarian cancers [12]. More
tumor cells and being retained for long periods of time,
studies based on the triazine scaffold toward anti-tumor
has attracted much attention [1]. This property of por-
activity have been carried out [13–15].
phyrins provides the possibility for their use as targeting
Herein, we report the selective synthesis of the substi-
reagents in the design of anti-cancer drugs. Accordingly,
tuted triazine porphyrins using a one-pot procedure from
the design and synthesis of the potential targeting anti-
the reaction of tetraphenylporphyrin bearing the hydroxyl
cancer drugs deriving from porphyrins has currently
group with 2,4,6-trichloro-1,3,5-triazine, and then with
aroused widespread interest [2].
amines or alcohols in high yield. Through this method,
We are interested in the synthesis of linking a drug moi-
we have synthesized ten new triazine porphyrins shown
ety to a porphyrin ring and evaluated their cytotoxic activity
in Fig. 1. The primary anti-cancer activities of these com-
in the absence of light. From previous studies, porphyrin-
pounds toward MCF-7 cancer cells were investigated
bearing drug moieties could make the concentration of
the drugs in tumor tissue higher than in surrounding nor-
in vitro in the absence of light. The results showed that
these triazine porphyrins have anti-cancer activities, and
mal tissue due to the tumor-affinity property of porphy-
point to their use as potential drugs for treatment of can-
rin [3–5]. Thus, it is possible to avoid or mitigate the side
cerous tumors.
effects of drugs at the same dosages of the drugs.
Triazine derivatives have been widely studied due to its
broad range of biological activities, such as anti-microbial
effects [6], Erm (erythromycin-resistance methylase)
methyltransferase inhibition [7], anti-trypanosomal
RESULTS AND DISCUSSION
Synthesis of substituted 1,3,5-triazine porphyrin
derivatives
š
SPP full member in good standing
*
Correspondence to: Can-Cheng Guo, email: ccguo@hnu.edu.cn,
The substituted triazine porphyrin 1–10 were the meso-
tel: +86 731-88821314, fax: +86 731-88821488
substituted AB porphyrins. Until now, the Adler-Longo
3
Copyright © 2010 World Scientific Publishing Company

124
S.-C. XIAO ET AL.
no corresponding triazine porphyrins
could be generated. All the compounds
obtained were the black polymers due
to the condensation of pyrrole with
triazines. Therefore, the Adler-Longo
and Lindsey methods are not suitable
for the synthesis of substituted triazine
porphyrins.
It is necessary to synthesize the
substituted triazine porphyrins. In
order to obtain substituted triazine
porphyrins 1–10, the synthetic route
in Scheme 1 was proposed.
As shown in Scheme 1, 5-(4-hydro-
xylphenyl)-10,15,20-tri-(4-phenyl)
porphyrin a was prepared according to
procedures described in literature [17].
Compound a was first treated with
cyanuric trichloride in the presence
of NaHCO and CHCl below 35 °C for 5 hours to gener-
Fig. 1. Structures of ten triazine porphyrins
3
3
method and Lindsey methods have been the best for the
ate compound b without isolatation. The mixture com-
pound b was further converted to the target compounds
1–10, respectively, with the corresponding alcohols or
amines in NaOH/CHCl3.
It is well known that three chlorine substituents on
the cyanuric trichloride are relatively active and they
may be substituted by nucleophiles under suitable condi-
tions [18]. When compound a was treated with cyanuric
trichloride at 30–35 °C, compound b was isolated as the
main product with a high yield. However, if the reac-
tion was carried out at > 35 °C, a few side products were
generated. This makes it difficult to isolate and purify
the desired compound b. In addition, the reaction was
synthesis of AB by direct condensation of substituted
3
benzaldehyde with pyrrole [16]. The key to the synthesis
of the triazine porphyrins 1–10 is how to introduce the
substituted triazine to the porphyrin ring. An attempt was
made in our laboratory to synthesize porphyrins 1–10 via
the Adler-Longo method by refluxing triazine-substituted
benzaldehyde and pyrrole in propionic acid, or via Lind-
sey method by the reaction of triazine-substituted benzal-
dehyde with pyrrole in BF ·Et O/CH Cl . Unfortunately,
3
2
2
2
no desired products were obtained. In our synthesis, the
reactions were run for different acids, solvents and the
reaction temperatures, but it was found that at all cases,
Scheme 1. Synthetic route of 1,3,5-triazine porphyrin derivatives
Copyright © 2010 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2010; 14: 124–127

TRIAZINE-PORPHYRINS AS POTENTIAL ANTI-CANCER AGENTS
125
much slower if conducted at < 30 °C. The conversion of
compound a to b was performed under basic conditions.
Bases such as NaHCO, Na CO, K CO, pyridine, and
triethylamine have no distinct effect on the reaction.
An attempt to generate a bi-porphyrin derivative by
treating compound b with compound a was not successful
even under higher temperature, with longer reaction time,
or with a stronger base. However, compound a was able to
react with small nucleophiles such as alcohols or amines to
afford compounds 1–10.
The second and third chlorine sunstituents on the
triazine moiety of compound b could be substituted by
amines to give the corresponding products. For example,
compounds 5–10 were obtained by treating compound b
withmethylamine, domethylamine, ethylamine, 2-chloro-
ethylamine, N,N-di(2-chloroethyl)amine and N-phenyl-
piperazine respectively. However, the nucleophilic
substituion was much slower when lower amounts of
nucleophilic alcohols were employed. For instance, it
took 20–24 h to obtain compounds 1–2 by reacting com-
pound b with methanol or ethanol. Furthermore, when
compound was refluxed with n-propanol or i-propanol
for 48 h, only monosubstituted products 3 and 4 were
obtained.
to 5-fluorouracil and hematoporphyrin. The tetraphe-
nylporphyrin was significantly less active against tested
cancer cell lines in the absence of light. This result is in
agreement with previous studies [3, 4] and show that
tetraphenylporphyrin has low dark cytotoxicity.
In summary, a series of 1,3,5-triazine porphyrin deriva-
tives were synthesized and evaluated for their in vitro cyto-
toxicity against MCF-7 cells in the absence of light. The
results showed these hybrid porphyrins possess good anti-
cancer activities. Further biological evaluation and mecha-
nistic studies on this novel class of anti-cancer compounds
are currently in progress and will be reported in due course.
2
2
EXPERIMENTAL
Instruments and reagents
1
H NMR spectra were recorded on an INOVA-400
spectrometer, and the chemical shifts were reported on the
scale relative to TMS. Elemental analyses were obtained
on a PerkinElmer 2400 elementary analyzer. Mass spec-
tra were obtained on a Shimadzu QP-5000 mass spec-
trometer with ESI ionization mode and analyzer. UV-vis
absorption spectra were obtained with a PerkinElmer
L-17 UV-vis spectrophotometer.
The structures of these compounds were confirmed by
1
UV-vis, MS, H NMR spectra and elementary analysis.
The triazine-porphyrins 1–10 have the same wavelength
λmax of the Soret and Q bands. However, they have differ-
ent molar absorptivity ε.
Cell survival assay
The cytotoxic effects of the compounds on the MCF-7
cancer cells were determined by using the MTT assay
[20]. Cells were planted in 100 µL of medium at a con-
centration of 1 × 10 cells per well in 96-well microtiter
plates which had been incubated for 24 h at 37 °C under an
Anti-cancer activity
3
In order to study whether these synthetic triazine-
porphyrins have anti-cancer activity, compounds 1–10
and the reference compounds tetraphenylporphyrin,
hematoporphyrin and 5-fluorouracil, were evaluated for
their cell cytotoxicity using the MTT cytotoxicity assay
atmosphere of air containing 5% CO . Medium (100 µL)
containing the test drugs, which were dissolved in the
2
mixed solvent of H O and THF (8:1), was added to qua-
2
druplicate wells and incubated for additional 72 h. The
medium was then removed from the wells and 200 µL
[
19] in the absence of light. The IC values of the MCF-7
50
cells to these compounds are listed in Table 1.
The test results showed that all compounds have
similar activity against MCF-7 cells when compared
-1
MTT (1 µg.mL in complete medium) was added to each
well, and then incubated for another 3 h. The formazan
crystals were dissolved in 100 µL dimethylsulfoxide
buffered with 25 µL glycine-NaCl solution (0.1 M
glycine, 0.1 M NaCl, pH 10.5). The absorbance was
measured in an enzyme-linked immunoabsorbent
Table 1. Cytotoxicity of the target compounds against MCF-7 cells
a,b
in vitro
Compound
IC , µM
Compound
IC , µM
50
5
0
assay plate reader (Bio-Rad) at a wavelength of 570
nm. The concentration required for 50% inhibition
of cell viability (IC ) was calculated using the soft-
1
2
3
4
5
17
19
6
14
7
8
18.3
12
50
ware “Dose-Effect Analysis with Microcomputers”.
1
1
1
4.8
4.5
5
9
8.5
12.5
22.8
Typical synthesis procedure of 1,3,5-triazine
porphyrin 1–10
10
2
45
4
Hematoporphyrin
Tetraphenylporphyrin
A solution of cyanuric trichloride (73.5 mg,
.7
5
-fluorouracil
4
00 µmol) in 5 mL chloroform was added
a
to a chloroform (20 mL) solution of 5-(4-
hydroxylphenyl)-10,15,20-tri-(4-phenyl)porphyrin
(100 mg, 160 µmol) and sodium bicarbonate
The IC50 values represent the concentration which results in a 50%
b
decrease in cell growth after 72 h incubation. Values are means of
three experiments.
Copyright © 2010 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2010; 14: 125–127

126
S.-C. XIAO ET AL.
(
84 mg, 1 mmol), the reaction mixture was stirred for
(28.99), 551 (15.70), 639 (13.87). MS (ESI): m/z 796
(calcd. for [M + 1] 796).
+
another 5 hours with the temperature at 35 °C, after
which reaction was complete as witnessed by TLC
analysis (silica gel, petroleum ether/ethyl acetate =
5-[4-(4,6-diethylamino-[1,3,5]triazin-2-yl)phenyl]-
10,15,20-tri-(4-phenyl)porphyrin (7). Yield: 56.2%.
Anal. calcd. for C H N O: C, 76.96; H, 5.19; N, 15.84.
3
:1 (V/V)), showing the disappearance of porphyrin a
5
1
41
9
(
R = 0.21) and the formation of derivative b (R = 0.87).
Found: C, 77.24; H, 6.01; N, 15.89. UV-vis (CH Cl ):
f
f
2 2
-3
-1
-1
Product b was not isolated but was reacted further with
an excess of 3–5 mL corresponding alcohol or amine
and sodium hydroxide (40 mg, 1 mmol) and stirred at
λmax, nm (ε × 10 M .cm ) 419 (215.8), 516 (16.1),
550 (15.87), 637 (13.50). MS (ESI): m/z 796 (calcd. for
+
[M + 1] 796).
4
5 °C for 1 h and then for another 10 hours at reflux
5-[4-(4,6-bis(2-chloroethyl)amino-[1,3,5]triazin-
2-yl)phenyl]-10,15,20-tri-(4-phenyl)porphyrin (8). Yield:
51.9%. Anal. calcd. for C H Cl N O: C, 70.83; H, 4.55;
temperature. After removal of the solvent, the residue
was partitioned between CHCl (15 mL) and water
3
51 39
2
9
(
20 mL × 4). The organic phase was dried on MgSO4
N, 14.58. Found: C, 71.05; H, 4.49; N, 14.63. UV-vis
-3
-1
-1
and evaporated, and the crude product was purified by
column chromatography (silica gel, petroleum ether/
chloroform) to afford corresponding compound with
good yields (50–62%).
(CH Cl ): λ , nm (ε × 10 M .cm ) 420 (215.5), 516
2 2 max
(26.35), 568 (16.41), 642 (13.67). MS (ESI): m/z 863
+
(calcd. for [M + 1] 863).
5-[4-(4,6-bis-(bis-(2-chloroethyl))amino-[1,3,5]
triazin-2-yl)phenyl]-10,15,20-tri-(4-phenyl)porphy-
rin (9). Yield: 50.8%. Anal. calcd. for C H Cl N O: C,
5
-[4-(4,6-dimethoxy-[1,3,5]triazin-2-yl)phenyl]-10,
5,20-tri-(4-phenyl)porphyrin (1). Yield: 53.2%. Anal.
calcd. for C H N O : C, 76.45; H, 4.58; N, 12.74. Found:
1
5
5
45
4
9
66.89; H, 4.57; N, 12.67. Found: C, 66.89; H, 4.52; N,
4
9
35
7
3
-3
-1
-1
C, 76.23; H, 4.56; N, 12.62. UV-vis (CH Cl ): λmax, nm
(
6
7
12.87. UV-vis (CH Cl ): λ , nm (ε × 10 M .cm ) 421
2
2
2 2 max
-
3
-1
-1
ε × 10 M .cm ) 419 (213.3), 512 (21.8), 549 (12.56),
30 (11.4). MS (ESI): m/z 770 (calcd. for [M + 1]
(216.5), 517 (25.32), 568 (16.87), 647 (12.8). MS (ESI):
+
+
m/z 988 (calcd. for [M + 1] 988).
70).
5-[4-(4,6-di(4-phenylpiperazine)-[1,3,5]triazin-2-yl)
phenyl]-10,15,20-tri-(4-phenyl)porphyrin (10). Yield:
52.5%. Anal. calcd. for C H N O: C, 78.11; H, 5.38;
5
-[4-(4,6-diethoxy-[1,3,5]triazin-2-yl)phenyl]-10,
1
5,20-tri-(4-phenyl)porphyrin (2). Yield: 52.8%. Anal.
6
7
55 11
calcd. for C H N O : C, 76.77; H, 4.93; N, 12.99. Found:
N, 14.96. Found: C, 78.23; H, 5.35; N, 14.82. UV-vis
5
1
39
7
3
-3
-1
-1
C, 76.58; H, 5.01; N, 13.20. UV-vis (CH Cl ): λmax, nm
(CH Cl ): λ , nm (ε × 10 M .cm ) 422 (218.5), 520
2
2
2 2 max
-
3
-1
-1
(
6
7
ε × 10 M .cm ) 419 (212.6), 513 (27.1), 550 (13.42),
31 (10.46). MS (ESI): m/z 798 (calcd. for [M + 1]
(27.97), 570 (16.52), 649 (12.8). MS (ESI): m/z 1030
+
+
(calcd. for [M + 1] 1030).
98).
5
-[4-(4-chloro-6-propoxy-[1,3,5]triazin-2-yl)
Acknowledgements
phenyl]-10,15,20-tri-(4-phenyl)porphyrin (3). Yield:
The authors gratefully thank the financial support
of the National Natural Science Foundation of China
5
4
0.3%. Anal. calcd. for C H ClN O : C, 74.85; H,
50 36 7 2
.52; N, 12.22. Found: C, 75.01; H, 4.61; N, 12.06. UV-
(Grants CN J0830415 and 20502005).
-
3
-1
-1
vis (CH Cl ): λ , nm (ε × 10 M .cm ) 418 (218.5),
2
2
max
5
10 (27.5), 543 (15.28), 628 (12.1). MS (ESI): m/z 802
Supporting information
+
(
calcd. for [M + 1] 802).
-[4-(4-chloro-6-isopropoxy-[1,3,5]triazin-2-yl)
phenyl]-10,15,20-tri-(4-phenyl)porphyrin (4). Yield:
1
5
The H NMR spectra of all the triazine-porphyrins
are given in the supplementary material. This material is
available free of charge via the Internet at http://www.
worldscinet.com/jpp/jpp.shtml.
5
4
0.6%. Anal. calcd. for C H ClN O : C, 74.85; H,
50 36 7 2
.52; N, 12.22. Found: C, 74.98; H, 4.59; N, 12.17. UV-
-
3
-1
-1
vis (CH Cl ): λ , nm (ε × 10 M .cm ) 418 (217.5),
2
2
max
5
10 (25.7), 543 (14.28), 628 (11.1). MS (ESI): m/z 802
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+
(
calcd. for [M + 1] 802).
-[4-(4,6-dimethylamino-[1,3,5]triazin-2-yl)
phenyl]-10,15,20-tri-(4-phenyl)porphyrin (5). Yield:
0.6%. Anal. calcd. for C H N O: C, 76.64; H, 4.86;
5
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Copyright © 2010 World Scientific Publishing Company
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TRIAZINE-PORPHYRINS AS POTENTIAL ANTI-CANCER AGENTS
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