Synthesis of symmetrical 1,5-bis-thio-substituted anthraquinones for cytotoxicity in cultured tumor cells and lipid peroxidation

Article abstract of DOI:10.1248/cpb.50.1491

The synthesis of a series of anthraquinone moieties bearing symmetrical sulfur-linked substituents in the 1 and 5 positions is described. These compounds were evaluated for their ability to inhibit the growth of suspended rat glioma C6 cells and human hepatoma G2 cells, respectively. In addition, the redox property of the compounds was determined based on the inhibition of lipid peroxidation in model membranes. Compounds 2a and 2h in this series compared favorably and exhibited the most potent cytotoxicity (0.02, 0.05 μM) against C6 cells in the XTT colorimetric assay. As far as redox properties are concerned, all bis-thio-anthraquinones show potential lipid peroxidation in model membranes very close to that of mitoxantrone (MX), and 2a, 2d, 2e, 2i, 2j, and 2k have more potential than that of MX. The lack of cytotoxicity of compound 2i cannot be related to lipid peroxidation, but the steric and electronic properties of the side-chain substituent maybe impair effective recognition of the cleavable complex. In contrast to MX, 2a and 2h are cytotoxic in rat glioma C6 cells and do not enhance lipid peroxidation in model membranes.

Full text of DOI:10.1248/cpb.50.1491

November 2002
Notes
Chem. Pharm. Bull. 50(11) 1491—1494 (2002)
1491
Synthesis of Symmetrical 1,5-bis-thio-Substituted Anthraquinones for
Cytotoxicity in Cultured Tumor Cells and Lipid Peroxidation
Hsu-Shan HUANG, ,a Jeng-Fong CHIOU,b Hui-Fen CHIU,c Jing-Min HWANG,d Pen-Yuan LIN,e
*
a
Chi-Wei TAO,f Pen-Fong YEH,f and Wei-Ren JENG
a School of Pharmacy, National Defense Medical Center; d Department of Radiation Oncology, National Defense Medical
Center; Neihu 114, Taipei, Taiwan, R.O.C: b Department of Radiotherapy and Oncology, Taipei Medical University;
c
e School of Pharmacy, Taipei Medical University; Taipei: Department of Pharmacology, Kaohsiung Medical University;
f
Kaohsiung: and Cheng-Hsin Medical Center; Taipei, Taiwan, R.O.C. Received May 8, 2002; accepted July 30, 2002
The synthesis of a series of anthraquinone moieties bearing symmetrical sulfur-linked substituents in the 1
and 5 positions is described. These compounds were evaluated for their ability to inhibit the growth of suspended
rat glioma C6 cells and human hepatoma G2 cells, respectively. In addition, the redox property of the com-
pounds was determined based on the inhibition of lipid peroxidation in model membranes. Compounds 2a and
2h in this series compared favorably and exhibited the most potent cytotoxicity (0.02, 0.05 mM) against C6 cells in
the XTT colorimetric assay. As far as redox properties are concerned, all bis-thio-anthraquinones show potential
lipid peroxidation in model membranes very close to that of mitoxantrone (MX), and 2a, 2d, 2e, 2i, 2j, and 2k
have more potential than that of MX. The lack of cytotoxicity of compound 2i cannot be related to lipid peroxi-
dation, but the steric and electronic properties of the side-chain substituent maybe impair effective recognition of
the cleavable complex. In contrast to MX, 2a and 2h are cytotoxic in rat glioma C6 cells and do not enhance lipid
peroxidation in model membranes.
Key words anthraquinone; cytotoxicity; lipid peroxidation; rat glioma C6 cell; human hepatoma G2 cell
The anthraquinone mitoxantrone (MX) has been shown to tivity.
have outstanding antitumor activities but a much narrower
spectrum of activity in comparison with those of the anthra- Chemistry
cyclines.1) Its planarity allows an intercalation between base
We report here a convenient synthetic pathway that leads
pairs of DNA in the conformation, while its redox properties to symmetrically substituted 1,5-bis-thio-anthraquinone de-
are linked to the production of radical species in biological rivatives. Moreover, the preliminary ESR studies revealed
systems.2) The chemical and biological activity exhibited by that the reduction power of anthracenones substituted with an
anthraquinone compounds is greatly affected by the different electron-withdrawing group in the C-10 position is impeded,
substituents of the planar ring system.3—6) It appears that the whereas that of 10-thio derivatives is increased.16,17) The re-
relative location of the planar and side-chain groups plays a action undergoes a nucleophilic substitution at the 1 and 5
major role in affecting enzyme function and sequence speci- positions with the appropriate thiols in the presence of
ficity.7—9) In MX and active congeners, the substituents are sodium methoxide and THF at room temperature or after re-
linked to the anthraquinone structure via a C–S linkage.
flux for 1 to 2 h to generate this structural class of an-
We have recently started to explore the changes in the thraquinones. The mechanism for the reaction may be ratio-
physicochemical and biological properties of unsymmetrical nalized assuming that thiols are ionized by sodium methox-
substituted anthracenes and symmetrical substituted an- ide as nucleophiles undergo nucleophilic substitution.
thraquinones, which exhibit unsymmetrical and symmetrical
The synthesis of 1,5-bis-thio-anthraquinone derivatives
bis-substituted C–O–C and C–S–C linkage between the pla- shown in Chart 1 was accomplished using procedures some-
nar ring system and the side-chain substituents.10—15) Struc- what modified from those described elsewhere.10—12) The
ture–activity relationship studies led to the discovery of sym- structural assignments for the symmetrical products as 2a—k
1
metrical thio-substituted anthraquinones, which showed po- are based on H- and 13C-NMR data. Compound 2a has ab-
tent cytotoxicity with in terms of mean IC50 value in cultured sorption for the H-4,8 protons at d 8.11 (t, 2H), H-3,7 pro-
tumor cells and lipid peroxidation, respectively. Since some tons at d 7.66 (t, 2H), and H-2,6 protons at d 7.60 (d, 2H),
of the compounds retained remarkable biological activity, respectively. Furthermore, the 13C-NMR spectra of these
this class appears to be worthy of further examination.
compounds exhibited carbonyl resonance of an anthra-
Compounds 2a and 2h showed potent cytotoxicity against
rat glioma C6 cells, with IC50 values of 0.02 and 0.05 mM, re-
spectively, comparable to that of MX (IC50 value of 0.07 mM).
The goal of the present study was an evaluation of the impor-
tance of the symmetrical bis-thio-substituted side-arm pat-
terns at the 1 and 5 positions of the anthraquinone ring sys-
tem. Not only would the nature of the side arms influence the
binding of the anthraquinone-DNA intercalant, but they also
might be intimately involved in lipid peroxidation. This has
enabled us to address the issue of how, and to what extent,
the position of side-chain substituents affects biological ac-
Chart 1
∗ To whom correspondence should be addressed. e-mail: huanghs@ndmctsgh.edu.tw
© 2002 Pharmaceutical Society of Japan

1492
Vol. 50, No. 11
Table 1. Cytotoxicity against the Growth of Suspended Murine and
Human Tumor Cell Lines and Inhibitory Effect of Anthraquinone Deriva-
tives on Iron-Induced Lipid Peroxidation in Rat Brain Homogenates
quinone chemical shift in the d 183.3—182.4 region for C-
9,10. In addition, 1H- and 13C-NMR correlations of these and
other data allowed for assignments and are included in the
experimental protocols.
A study of the effects of substituents on the electronic
spectrum of anthraquinone showed that the nature and num-
ber of the substituents, as well as their position in the an-
thraquinone nucleus, play a major role. Anthraquinone may
be considered to consist of two isolated benzoyl chromogens
in which little or no interaction would be expected between
substituents located in different benzene rings. In contrast,
electron-donating substitutents can have a significant effect
(bathochromic shift), producing dyes that vary in color from
yellow through red.18)
IC50 (mM)a)
LP (%)
Compound
R
(10 mM)b)
Hep G2c)
C6 cellsd)
2a
2b
2c
2d
2e
2f
2g
2h
2i
CH2CH3
CH2CH2OH
CH2CH2CH3
12.2ꢁ1.1 0.02ꢁ0.01 83ꢁ2.2
36.4ꢁ1.5 21.5ꢁ0.8
75.1ꢁ2.5 29.9ꢁ2.1
16ꢁ2.2
15ꢁ1.5
83ꢁ1.1
54ꢁ1.9
5ꢁ0.5
CH2CH(OH)CH2OH 34.3ꢁ1.8 38.5ꢁ1.5
Results and Discussion
(CH2)6OH
2-NH2C6H4
3-NH2C6H4
4-NH2C6H4
49.3ꢁ2.1 31.7ꢁ1.6
34.0ꢁ1.7 15.1ꢁ1.7
21.5ꢁ1.2 26.3ꢁ2.8
Anthracyclines and anthraquinones form ternary com-
plexes with DNA and the enzyme and stimulate DNA cleav-
age in a sequence-specific manner.19) The cytotoxicity of a
series of symmetrical bis-substituted anthraquinone deriva-
tives were studied against murine and human cultured tumor
cells using the lipid peroxidation assay. Their cytotoxicity
properties were compared with that of MX as documented by
the reactivity of the novel compounds and potent in vitro ac-
tivity against C6 cells and hep G2 cells over a wide range of
structural variants. There did not appear to be any correlation
between these two cell lines. In addition, the redox property
of the compounds for the inhibition of lipid peroxidation in
model membranes was determined. Compounds 2a and 2h
possess potent cytotoxicity with IC50 values of 0.02 and
0.05 mM in the inhibition of rat glioma C6 cell growth in cul-
ture by using the XTT colorimetric assay, while their antipro-
liferative activity is markedly enhanced and comparable to
that of the positive control MX, which had an IC50 value of
0.07 mM.
6ꢁ0.9
17.4ꢁ1.5 0.05ꢁ0.01 20ꢁ1.4
CH2C6H5
41.5ꢁ2.5 38.2ꢁ4.4
28.6ꢁ1.2 25.1ꢁ2.8
36.9ꢁ1.5 32.9ꢁ3.3
ꢂ100
67ꢁ2.9
69ꢁ1.5
2j
2k
CH2C6H4(OCH3)(p)
CH2CH2C6H5
Mitoxantrone
Ascorbic acid
(ꢀ)-a-Tocopherol
Anthrarufin
2.0ꢁ0.5 0.07ꢁ0.01 54ꢁ1.5
ꢂ100
ꢂ100
ꢃ36ꢁ1.9
a) IC50, drug concentration inhibiting 50% of cellular growth following 48 h of drug
exposure. Values are in mM and represent an average of three experiments. The variance
for the IC50 values was less than ꢁ20%. Inhibition of cell growth was significantly dif-
ferent with respect to that of the control; nꢄ3 or more, pꢅ0.01. b) Relative percent-
age of inhibition. Inhibition was compared with that of the control (ascorbic acid, a-to-
copherol and mitoxantrone-HCl), pꢅ0.01, meanꢁS.E., nꢄ4. Values are mean percent
inhibition at the indicated concentration (mM), and standard errors. c) Hep G2,
human hepatoma G2 cells. d) C6 cells, rat glioma C6 cells.
Table 2. Inhibitory Effects of 2i on Iron-Induced Lipid Peroxidation in Rat
Brain Homogenates
The degree of peroxidation is related to the formation of
thiobarbituric acid-reactive compounds and is expressed rela-
tive to that of malondialdehyde (MDA).20) It is also a mea-
sure of hydroxyl radical generation and thus reflects the
prooxidant properties of the anthraquinones. Various data
have emphasized the significance of free radicals and end-
products derived from the lipid peroxidation of compounds
that may help prevent tissue injury. Most of the an-
thraquinones examined, e.g., 2a, 2d, 2e, 2j, and 2k, exhibit
greater lipid peroxidation than that of MX and, except for 2a
and 2h cytotoxic properties, considerably better than that of
MX. The bis-ethyl-thio analogue 2a showed potential cyto-
toxicity against the C6 cell line when compared with MX;
the bis(p-aminophenyl-thio) substitution of 2h also showed
good cytotoxicity. Compound 2i exhibited stronger antioxi-
dant activity than ascorbic acid, (ꢀ)-a-tocopherol, an-
thrarufin, and MX as further evaluated at several concentra-
tions against positive controls with lipid peroxidation (Table
2). At the concentration of 0.01 mM, 2i retained activity of
24%, the activity of ascorbic acid decreased to 10%, and
(ꢀ)-a-tocopherol had no effect at 0.1 mM. In conclusion, this
study confirms the dual-function activity the tested com-
pounds against both suspended rat glioma C6 cells and
human hepatoma G2 cells and lipid peroxidation and sug-
gests that some symmetrical anthraquinone derivatives may
be useful for the treatment of tumors.
Inhibition (%)a)
Compound
10 mM
1 mM
0.1 mM
0.01 mM
2i
ꢂ100
100
100
95
60ꢁ2.0
32ꢁ1.2
0
24ꢁ0.8
10ꢁ0.6
0
Ascorbic acid
(ꢀ)-a-Tocopherol
Mitoxantrone-HCl
75ꢁ1.5
55ꢁ1.7
54ꢁ2.1
100
22ꢁ3.5
5ꢁ0.3
a) Relative percentage of inhibition. Inhibition was compared to that of the control
(ascorbic acid, (ꢀ)-a-tocopherol and mitoxantrone-HCl), pꢅ0.01, meanꢁS.E., nꢄ4.
Values are mean percent inhibition at the indicated concentration (mM) with standard
errors.
Experimental
Melting points were determined with a Büchi B-545 melting point appa-
ratus and are uncorrected. All reactions were monitored by TLC (silica gel
60 F254), flash-column chromatography: silica gel (E. Merck, 70—230 mesh)
with CH2Cl2 as the eluent. 1H-NMR: Varian GEMINI-300 (300 MHz) and
Brucker AM-500 (500 MHz); d values are in ppm relative to TMS as an in-
ternal standard. Fourier-transform IR spectra (KBr): Perkin-Elmer 983G
spectrometer. The UV spectra were recorded on a Shimadzu UV-160A.
Mass spectra (EI, 70 eV, unless otherwise stated): Finnigan MAT TSQ-46
and Finnigan MAT TSQ-700 (Universität Regensburg, Germany). Typical

November 2002
1493
experiments illustrating the general procedures for the preparation of the an-
thraquinones are described below.
General Procedure for the Preparation of 1,5-bis-thio-Anthra- d, Jꢄ7.4 Hz), 7.45 (4H, d, Jꢄ7.4 Hz), 7.62 (2H, d, Jꢄ8.0 Hz), 7.66 (2H, t,
1,5-bis-Benzylthio-anthraquinone (2i): 78% yield. mp 281—282 °C
(THF). 1H-NMR (CDCl3) d: 4.23 (4H, s), 7.27 (2H, t, Jꢄ7.3 Hz), 7.33 (4H,
quinones To a solution of 1,5-dichloroanthraquinone (1.0 g, 3.6 mmol) in
dry THF (100 ml) a solution of an appropriate thiols (28.8 mmol) in sodium
methoxide (1.56 g, 28.8 mmol) and dry methanol (30 ml) under N2 was
Jꢄ7.4 Hz), 8.10 (2H, d, Jꢄ7.1 Hz). 13C-NMR (CDCl3) d: 37.35, 123.76,
127.58, 127.91, 128.78, 129.10, 129.59, 133.32, 135.41, 135.86, 144.92,
183.31. IR (KBr) cmꢃ1: 1653, 1261. UV lmax (CHCl3) nm (log e): 476
added dropwise. The reaction mixture was refluxed for 1 h. Water (250 ml) (1.50). MS m/z: 452 (Mꢀ), 361, 270, 91. Anal. Calcd for C28H20O2S2: C,
was added, and then the mixture was extracted with dichloromethane. The 74.30; H, 4.55. Found: C, 74.55; H, 4.78.
combined organic extracts were washed with water, dried (MgSO4), and
1,5-bis(p-Methoxybenzylthio)-anthraquinone (2j): 62% yield. mp 297—
concentrated. The resulting precipitate was collected by filtration, washed 299 °C (THF). HR-FAB-MS m/z: 512.6472 (Calcd for C30H24O4S2:
with water and further purified by chromatography and crystallization.
1,5-bis-Ethylthio-anthraquinone (2a): 66% yield. mp 235—236 °C (THF).
1H-NMR (CDCl3) d: 1.45 (6H, t, Jꢄ7.4 Hz), 3.01 (4H, q, Jꢄ7.4 Hz), 7.60
(2H, d, Jꢄ8.0 Hz), 7.66 (2H, t, Jꢄ7.8 Hz), 8.11 (2H, t, Jꢄ7.6, 0.9 Hz). 13C-
512.6492).
1,5-bis-Phenylethylthio-anthraquinone (2k): 69% yield. mp 209—210 °C
(THF). 1H-NMR (CDCl3) d: 3.08 (4H, t, Jꢄ8.0 Hz), 3.25 (4H, t, Jꢄ8.1 Hz),
7.28 (2H, t, Jꢄ7.0 Hz), 7.30 (2H, t, Jꢄ8.3 Hz), 7.32 (2H, d, Jꢄ7.4 Hz), 7.62
NMR (CDCl3) d: 12.77, 25.96, 123.47, 127.89, 129.26, 133.14, 136.09, (2H, d, Jꢄ7.4 Hz), 7.66 (2H, t, Jꢄ7.7 Hz), 8.12 (2H, d, Jꢄ6.2 Hz). 13C-
145.03, 183.33. IR (KBr) cmꢃ1: 1651, 1202. UV lmax (CHCl3) nm (log e):
NMR (CDCl3) d: 33.64, 34.28, 123.65, 126.68, 128.02, 128.43, 128.69,
503 (2.41). MS m/z: 328 (Mꢀ), 299, 267, 239, 139. Anal. Calcd for 129.31, 133.22, 136.07, 140.04, 144.64, 183.29. IR (KBr) cmꢃ1: 1653,
C18H16O2S2: C, 65.82; H, 4.91. Found: C, 65.65; H, 4.88.
1204. UV lmax (CHCl3) nm (log e): 512 (0.60). MS m/z: 480 (Mꢀ), 285.
Anal. Calcd for C30H24O2S2: C, 74.96; H, 5.03. Found: C, 74.75; H, 4.91.
Cytotoxic Evaluations (XTT Colorimetric Assay) Tumor cell lines
1,5-bis-Hydroxyethylthio-anthraquinone (2b): 45% yield. mp 261—
1
262 °C (DMSO). H-NMR (CDCl3) d: 3.12 (4H, t, Jꢄ6.5 Hz), 3.70 (4H, q,
Jꢄ6.2 Hz), 5.04 (2H, t, Jꢄ5.5 Hz), 7.78 (2H, d, Jꢄ7.6 Hz), 7.82—7.80 (2H, used were rat glioma C6 cells and human hepatoma G2 cells. The cells
m), 7.94 (2H, dd, Jꢄ6.8, 1.5 Hz). 13C-NMR (CDCl3) d: 34.04, 59.06,
122.84, 127.42, 129.88, 133.57, 135.55, 144.07, 182.35. IR (KBr) cmꢃ1
1638, 1204. UV lmax (CHCl3) nm (log e): 513 (2.48). MS m/z: 360 (Mꢀ),
(2.5ꢆ104 cells/ml) were placed into 96-well plates and preincubated for 24
to 72 h in complete medium. The drug concentration inhibiting 50% of cel-
lular growth (IC50, mg/ml) was determined using the XTT assay following
:
324. Anal. Calcd for C18H16O4S2: C, 59.98; H, 4.47. Found: C, 59.81; H, 72 h of drug exposure.21) The results are the means of at least three indepen-
4.38.
dent experiments unless otherwise indicated.
1,5-bis-Propylthio-anthraquinone (2c): 69% yield. mp 232—233 °C
Assay of Lipid Peroxidation Rat brain homogenate was prepared from
(THF). 1H-NMR (CDCl3) d 1.13 (6H, t, Jꢄ7.4 Hz), 1.83 (4H, m), 2.96 (4H, the brains of freshly killed Wistar rats, and its peroxidation in the presence
t, Jꢄ7.4 Hz), 7.60 (2H, d, Jꢄ7.9 Hz), 7.65 (2H, t, Jꢄ7.8 Hz), 8.11 (2H, d, of iron ions was measured using the thiobarbituric acid method as previously
Jꢄ6.9 Hz). 13C-NMR (CDCl3) d: 13.96, 21.33, 34.04, 123.46, 127.99,
described.10—13,22) The extent of lipid peroxidation was estimated in terms of
129.32, 133.12, 136.14, 145.20, 183.35. IR (KBr) cmꢃ1: 1649, 1199. UV thiobarbituric acid-reactive substances and was read at 532 nm on a spec-
l
max (CHCl3) nm (log e): 485 (2.25). MS m/z: 356 (Mꢀ), 313, 271, 239, 139. trophotometer (Shimadzu UV-160). The results of this assay are shown in
Anal. Calcd for C20H20O2S2: C, 67.38; H, 5.65. Found: C, 67.55; H, 5.78.
1,5-bis-Dihydroxypropylthio-anthraquinone (2d): 45% yield. mp 238—
239 °C (DMSO). 1H-NMR (CDCl3) d: 2.93 (2H, t, Jꢄ10.1 Hz), 3.20 (2H,
Tables 1 and 2.
Acknowledgments This research was partially supported by grants
dd, Jꢄ12.7, 4.2 Hz), 3.41—3.50 (4H, m), 3.73 (2H, m), 4.79 (2H, t), 5.12 from the National Defense Medical Center. The authors are indebted to Dr.
(2H, d, Jꢄ5.3 Hz), 7.79 (2H, t, Jꢄ7.7 Hz), 7.82 (2H, d, Jꢄ7.4 Hz), 7.94 (2H, Klaus K. Mayer (Universität Regensburg, Germany) for the mass spectrome-
t, Jꢄ7.3, 0.8 Hz). 13C-NMR (CDCl3) d: 35.53, 65.05, 69.91, 122.75, 127.39, try analytical determinations.
130.02, 133.56, 135.55, 144.71, 182.41. IR (KBr) cmꢃ1: 1647, 1202. UV
lmax (CHCl3) nm (log e): 507 (2.48). MS m/z: 420 (Mꢀ), 348. Anal. Calcd References
for C20H20O6S2: C, 57.12; H, 4.79. Found: C, 57.35; H, 4.98.
1) Krapcho A. P., Petry M. E., Hacker M. P., J. Med. Chem., 33, 2651—
2655 (1990).
2) Gatto B., Zagotto G., Sissi C., Cera C., Uriarte E., J. Med. Chem., 39,
3114—3122 (1996).
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(1978).
4) Zee-Cheng R. K. Y., Podrebarac E. G., Menon C. S., Cheng C. C., J.
Med. Chem., 22, 501—505 (1979).
1,5-bis-Hydroxyhexylthio-anthraquinone (2e): 79% yield. mp 195—
1
196 °C (DMSO). H-NMR (CDCl3) d: 1.37 (4H, q, Jꢄ6.9 Hz), 1.46 (4H, q,
Jꢄ6.9 Hz), 1.49 (4H, q, Jꢄ7.5 Hz), 1.70 (4H, q, Jꢄ7.3 Hz), 3.00 (4H, t,
Jꢄ7.2 Hz), 3.41 (4H, q, Jꢄ5.9 Hz), 4.10 (2H, t, Jꢄ5.1 Hz), 7.77—7.80 (4H,
m), 7.95 (2H, d, Jꢄ6.5 Hz). 13C-NMR (CDCl3) d: 24.79, 27.31, 28.10,
30.77, 32.04, 60.41, 122.41, 127.18, 129.64, 133.13, 135.34, 144.10, 181.98.
IR (KBr) cmꢃ1: 1643, 1259. UV lmax (DMSO) nm (log e): 564 (0.32). MS
m/z: 472 (Mꢀ), 474. Anal. Calcd for C26H32O4S2: C, 66.06; H, 6.82. Found:
C, 66.35; H, 6.98.
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Med. Chem., 22, 1024—1030 (1979).
1,5-bis(o-Aminophenylthio)-anthraquinone (2f): 55% yield. mp 283—
284 °C (DMSO). H-NMR (CDCl3) d: 5.37 (4H, s), 6.66 (2H, t, Jꢄ7.5 Hz),
6) Krapcho A. P., Getahun Z., Avery K. L., Jr., Vargas K. J., Hacker M. P.,
J. Med. Chem., 34, 2373—2380 (1991).
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25004—25009 (1994).
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Pharmacol., 45, 908—915 (1994).
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1
6.85 (2H, d, Jꢄ8.1 Hz), 7.01 (2H, d, Jꢄ8.2 Hz), 7.25 (2H, t, Jꢄ7.6, 0.9 Hz),
7.34 (2H, d, Jꢄ7.5 Hz), 7.66 (2H, t, Jꢄ7.9 Hz), 8.00 (2H, d, Jꢄ7.4 Hz). 13C-
NMR (CDCl3) d: 111.35, 115.06, 117.03, 123.67, 127.77, 130.43, 131.77,
133.41, 135.51, 137.08, 143.20, 150.66, 182.65. IR (KBr) cmꢃ1: 1651,
1256. UV lmax (DMSO) nm (log e): 508 (2.36). MS m/z: 454 (Mꢀ), 361.
Anal. Calcd for C26H18N2O2S2: C, 68.69; H, 3.99. Found: C, 68.55; H, 3.78.
1,5-bis(m-Aminophenylthio)-anthraquinone (2g): 65% yield. mp 292—
293 °C (DMSO). 1H-NMR (CDCl3) d: 5.40 (4H, s), 6.71—6.73 (4H, m),
6.80 (2H, s), 7.16 (2H, d, Jꢄ8.3 Hz), 7.19 (2H, t, Jꢄ7.8 Hz), 7.67 (2H, t,
Jꢄ7.9 Hz), 7.97 (2H, d, Jꢄ7.5 Hz). 13C-NMR (CDCl3) d: 115.41, 120.04,
122.24, 123.57, 126.59, 130.74, 130.94, 131.01, 133.49, 135.10, 145.53,
150.44, 182.42. IR (KBr) cmꢃ1: 1653, 1202. UV lmax (DMSO) nm (log e):
535 (2.48). MS m/z: 454 (Mꢀ), 125. Anal. Calcd for C26H18N2O2S2: C,
68.69; H, 3.99. Found: C, 68.49; H, 3.69.
13) Huang H. S., Hwang J. M., Jen Y. M., Tao C. W., Lee K. Y., Chin.
Pharm. J., 53, 71—83 (2001).
1,5-bis(p-Aminophenylthio)-anthraquinone (2h): 66% yield. mp 364—
14) Huang H. S., Chiu J. F., Chiu H. F., Chen R. F., Lai Y. L., Arch. Pharm.
Pharm. Med. Chem., 335, 33—38 (2002).
15) Halliwell B., Gutteridge J. M., Arch. Biochem. Biophys., 246, 501—
514 (1986).
16) Müller K., Huang H. S., Wiegrebe W., J. Med. Chem., 39, 3132—3138
(1996).
1
365 °C (DMSO). H-NMR (CDCl3) d: 5.64 (4H, s), 6.70 (4H, t, Jꢄ8.3 Hz),
7.07 (2H, d, Jꢄ8.3 Hz), 7.20 (4H, d, Jꢄ8.3 Hz), 7.63 (2H, t, Jꢄ7.9 Hz), 7.94
(2H, d, Jꢄ7.5 Hz). 13C-NMR (CDCl3) d: 114.01, 115.19, 123.28, 126.46,
130.57, 133.29, 135.19, 137.02, 147.69, 150.64, 182.41. IR (KBr) cmꢃ1
:
1649, 1283. UV lmax (DMSO) nm (log e): 557 (2.48). MS m/z: 454 (Mꢀ),
124. Anal. Calcd for C26H18N2O2S2: C, 68.69; H, 3.99. Found: C, 68.49; H, 17) Pecˇar S., Schara M., Müller K., Wiegrebe W., Free Radic. Biol. Med.,
3.68. 18, 459—465 (1995).

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