Synthesis and biological activities of topoisomerase I inhibitors, 6-arylmethylamino analogues of edotecarin

Article abstract of DOI:10.1021/jm801641t

The replacement of 1,3-dihydroxy-2-propylamino moiety at the N6-position of edotecarin (1) by arylmethylamino groups yielded a number of more potent topoisomerase I inhibitors with better cytotoxic (CTX) activities in vitro than edotecarin. Among them, th

Full text of DOI:10.1021/jm801641t

J. Med. Chem. 2009, 52, 3225–3237
3225
Synthesis and Biological Activities of Topoisomerase I Inhibitors, 6-Arylmethylamino Analogues
of Edotecarin
Satoshi Sunami,* Teruyuki Nishimura, Ikuko Nishimura, Satoru Ito, Hiroharu Arakawa, and Mitsuru Ohkubo
Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd, Okubo-3, Tsukuba 300-2611, Ibaraki, Japan
ReceiVed December 24, 2008
The replacement of 1,3-dihydroxy-2-propylamino moiety at the N6-position of edotecarin (1) by
arylmethylamino groups yielded a number of more potent topoisomerase I inhibitors with better cytotoxic
(CTX) activities in vitro than edotecarin. Among them, the three most potent pyridylmethyl analogues,
compounds 22g, 22m, and 23c, showed better antitumor activities against MKN-45 human stomach cancer
or MX-1 human breast cancer xenografted mice than those of edotecarin. Furthermore, compounds 22m
and 23c exhibited complete response against MX-1 cells implanted in mice.
Introduction
NSC-725776, the most advanced analogue of this series, has
been selected for clinical development.
Topoisomerase I inhibitors have a wide range of antitumor
activities and are among the most widely used anticancer drugs
clinically.1-4 Camptothecin was the first specific topoisomerase
I inhibitor to be used in clinical applications.4-8 Camptothecin
analogues such as irinotecan,1-4,9-17 topotecan,1-4,16-20 and
9-aminocamptothecin (9-ACa),9,17,21-23 which have superior
antitumor activities with acceptable toxicities, have shown
significant clinical activity. Their success has stimulated inten-
sive efforts in the improvement of the limitation of these
camptothecines, including chemical modifications to stabilize
the chemically unstable E-ring lactone moieties at phyiological
condition and/or to provide persistent accumulation in target
cells. The homocamptothecines,24-36 which were obtained by
expanding the E-ring from a six-membered R-hydroxylactone
ring to a seven-membered ꢀ-hydroxylactone ring, showed
enhanced plasma stability with increased topoisomerase I
inhibitory activity compared to camptothecines. Diflomotecan28-32
is the most advanced analogue of this series and now in phase
II clinical trial. On the other hand, introduction of lipophilic
substituents to the 7-position of camptothecine achieved the
rapid uptake, enhanced intracellular accumulation and prolonga-
tion/stabilization of the topoisomerase I-DNA-drug ternary
complex (cleavable complex) compared with conventional
camptothecines.37-41 Gimatecan,2-4,37-41 an orally active 7-sub-
stituted camptothecin analogue with promising antitumor effect
in vivo, has undergone phase II clinical study in advanced
epithelial ovarian, fallopian tube, and peritoneal cancers,
advanced breast cancer, malignant glioma,and metastatic col-
orectal cancer.2-4
Edotecarin (1) is a potent and specific indolocarbazole
topoisomerase I inhibitor2-4,42,50-52 developed by the chemical
derivatization53,54 of NB-506 (2).55-57 Like other topoisomerase
I inhibitors, the primary mechanism of action of edotecarin is
to bind to the topoisomerase I-DNA complex,58 resulting in
prevention of religation of single-strand breaks, which ultimately
leads to apoptosis and cell death. The cleavable complex formed
by edotecarin is more stable than that formed by camptothecin.58
As a result, edotecarin showed 8-fold more potent inhibition of
topoisomerase I mediated DNA cleavage than camptothecin.59
In preclinical studies, edotecarin exhibited a different and
improved therapeutic index against various human cancer cell
lines in vitro compared with camptothecin, adriamycin, etopo-
side, and cisplatin.58 Several in vivo studies demonstrated that
edotecarin is a potential new antineoplastic agent. Edotecarin,
when used as a single agent, produced significant antitumor
activities in xenografted nude mice of several different human
tumors such as LX-1 lung, PC-3 prostate, and central nervous
system tumors.60 In addition to monotherapy, recent in vivo
studies suggested that edotecarin may be useful in combination
with established treatment regimens for treating SK-BR-3 human
breast61 and HCT-116 human colon62 cancers. A phase I study,
which was designed to assess the maximum tolerated dose
(MTD) and pharmacokinetic (PK) profile, showed a recom-
mended dose of edotecarin for phase II trials with an attractive
PK profile.63,64 The toxicities in this phase I study were similar
to those typical of cytotoxic chemotherapy but less severe than
those associated with other topoisomerase I inhibitors. In
addition, in the first phase I study in the U.S., a confirmed partial
response was noted in one patient with bladder cancer refractory
to both paclitaxel/gemcitabine and second-line MVAC (meth-
otrexate, vinblastine, doxolubicin, and cisplatin) therapy and 12
other patients showed stabilization of the disease.63 In a second
phase I study in Japan, unconfirmed partial responses were also
observed in two patients, one with metastatic gastric carcinoma
and one with esophageal cancer.64 These studies demonstrated
that edotecarin is an attractive new anticancer drug. Edotecarin
has undergone phase II studies in irinotecan-refractory colorectal
cancer and breast cancer and phase III study in glioblastoma
multiforne.
Because of the recognition of topoisomerase I inhibitors as a
valuable target for the efficient antitumor agents, extensive effort
for the development of structurally diverse topoisomerase I
inhbitors has also been made. Among them, indenoisoquino-
lines42-49 are chemically stable and form much more stable
cleavable complexes than those formed by camptothecines.
* To whom correspondence should be addressed. Phone: +81-29-877-
2000. Fax: +81-29-877-2029. E-mail: satoshi_sunami@merck.com.
a Abbreviations: CTX, cytotoxicity; 9-AC, 9-aminocamptothecin; MTD,
maximum tolerated dose; PK, pharmacokinetic; MVAC, methotrexate,
vinblastine, doxolubicin, and cisplatin; TBDMS, tert-butyldimethylsilyl;
LAH, lithium aluminum hydride; TFA, trifluoroacetic acid; BocNHNH2,
tert-butyl carbazate; DIBAL, diisobutyl aluminum hydride; Boc, tert-
butoxycarbonyl; GID75, 75% growth inhibition dose; LD10, 10% lethal dose.
Recently, we found that 6-arylmethylamino analogues of
edotecarin showed superior in vitro CTX activities against
10.1021/jm801641t CCC: $40.75
2009 American Chemical Society
Published on Web 04/27/2009

3226 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 10
Sunami et al.
Figure 1
Scheme 1a
Scheme 2 illustrates the synthesis of the final compounds from
6-amino intermediate 19 and arylaldehydes. Arylaldehydes
(20a-k, 6, 10, 14, and 18) were reacted with compound 19 in
the presence of acetic acid in refluxing MeOH to provide
arylmethylhydrazones 21a-r. Three types of reaction conditions
were used to reduce the double bond of the hydrazone moieties
in 21a-r (conditions ii-iv), depending on the stability of the
products (22a-r) under each reaction condition. In most cases,
reduction with NaBH3CN in the presence of HCl (condition ii)
gave the final compounds in the best yields. However, in some
cases, because the newly formed benzyl C-N bond was cleaved
by the strong acidic media under condition ii, some (un)sub-
stituted pyridylmethyl and quinolylmethyl derivatives were
prepared by reduction with NaBH3CN-ZnCl2 (condition iii) or
catalytic hydrogenation (condition iv).
Compounds 26a-e were readily prepared from 6-amino
intermediates 19 or 24 by N-alkylation with arylmethylbromides
25a-e in DMF as shown in Scheme 3.
a Reagents and conditions: (i) (MeO)3CH, MeOH, reflux; (ii) LAH, THF,
rt; (iii) TFA, 70 °C; (iv) TBDMSCl, imidazole, DMF, rt; (v) NaBH4, CaCl2,
EtOH, 0 °C; (vi) MnO2, CH2Cl2, rt; (vii) Dess-Martin periodinate, CH2Cl2,
rt.
Reaction of arylmethylhydrazines (Ar-CH2NHNH2) and acid
anhydride intermediate 51 was also an efficient alternative
method to provide the final compounds As shown in Scheme
4, arylmethylhydrazines (32, 38, 44, and 50) were prepared by
reductive amination using tert-butyl carbazate (BocNHNH2) and
the corresponding aldehydes as a key step. Aldehyde 36 was
prepared from commercially available pyridine 3,5-dicarboxylic
acid 33. The two carboxylic acid groups in compound 33 were
reduced to hydroxymethyl groups with BH3-THF complex to
give compound 34. TBDMS protection of one hydroxymethyl
group of compound 34 using 1 equiv of TBDMSCl followed
by oxidation of the remaining hydroxymethyl group afforded
compound 36. Aldehyde 42 was obtained in a similar manner
as the synthesis of compound 6 in Scheme 1 from compound
39.66 Aldehyde 47 was synthesized by protection with TBDM-
SCl followed by diisobutyl aluminum hydride (DIBAL) reduc-
tion of the ethyl ester group of compound 45.67 Arylaldehydes
(27, 36, 42, and 47) were reacted with BocNHNH2 in EtOH to
give hydrazones (28, 37, 43, and 48). Reduction of the double
bond of the hydrazone moiety in phenyl derivative 28 was
conducted with NaBH3CN in acidic media to give compound
29. Transformation of the cyano group to ahydroxymethyl group
by consecutive treatment with DIBAL and NaBH4, followed
by removal of the tert-butoxycarbonyl (Boc) group with TFA,
gave the required hydrazine 32. Double bonds of the hydrazone
moieties in pyridyl derivatives 37, 43, and 48 were reduced with
BH3-THF complex in THF followed by acid treatment to
generate compounds 38, 44, and 49. The Boc group of
compound 49 was removed by TFA treatment to yield com-
pound 50.
various cell lines and antitumor activities against several human
cancer cells implanted in mice. In this paper, we wish to report
the synthesis and biological activities of 6-arylmethylamino
analogues A of edotecarin and discuss the in vivo anticancer
effects of several potent analogues (Figure 1).
Chemistry
Three types of methods to synthesize a series of 6-aryl-
methylamino analogues A of edotecarin were employed as
described in Schemes 2, 3, and 5, depending on the available
starting materials: (i) reaction of 6-amino intermediate 19 with
arylaldehydes, followed by reduction of the resultant hydrazones
(Scheme 2), (ii) reaction of 6-amino intermediates 19 or 24 with
arylmethylbromide (Scheme 3), (iii) Reaction of acid anhydride
intermediate 51 with arylmethylhydrazines (Scheme 5).
Pyridine carboaldehydes having tert-butyldimethylsilyl (TB-
DMS) protected (10, 14, and 18) or unprotected (6) hydroxy-
methyl groups, which were well-designed starting materials used
in Scheme 2, were prepared as summarized in Scheme 1.
Compound 6 was synthesized starting from ethyl 2-formylpy-
ridine-4-carboxylate 3.65 Acetalization with trimethyl-orthofor-
mate followed by reduction with lithium aluminum hydride
(LAH) gave acetal 5, which was converted to compound 6 by
hydrolysis with trifluoroacetic acid (TFA). Compounds 10, 14,
and 18 were prepared in a similar manner from compounds 7,
11, and 15, respectively. After protection of the hydroxymethyl
group in compounds 7, 11, and 15 with TBDMS groups,
reduction of the isopropyl ester group was conducted with
NaBH4-CaCl2 to give compounds 9, 13, and 17. Oxidation of
the newly formed hydroxymethyl group with MnO2 or
Dess-Martin periodinate led to compounds 10, 14, and 18.
Arylmethylhydrazines (32, 38, 44, 50, and 52a-b) were
reacted with acid anhydride intermediate 51 in the presence of

Topoisomerase I Inhibitors, Analogues of Edotecarin
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 10 3227
Scheme 2a
a Reagents and conditions: (i) AcOH, MeOH, reflux; (ii) NaBH3CN, 10% HCl/MeOH, rt; (iii) NaBH3CN, ZnCl2, THF, rt; (iv) H2/5% Pd-C, MeOH/THF,
rt; (v) TBAF, THF, rt.
Scheme 3a
a Reagents and conditions: (i) DMF, rt.
saturated aqueous NaHCO3 solution in DMF to provide final
compounds (53-58) as shown in Scheme 5.
Inhibitory activities of topoisomerase I in P388/S cells of
compounds 22a-22k (K+/SDS assays in P388/S cells) were
almost correlated with the CTX activities against P388/S cells
and comparable to that of edotecarin, suggesting that the CTX
activities of these analogues were observed mainly due to the
topoisomerase I inhibition. However, some data (compounds
22d and 22f) were deviated from the correlation. It may be due
to solid deposition of the compounds in the assay conditions
and enough concentration of the compounds to show activities
against the K+/SDS assay were not achieved within the short
incubation time (1 h). On the other hand, long incubation time
(72 h) for CTX assay enables the precipitation to dissolve in
the assay medium to exhibit strong CTX activities.
Once we identified the potent aromatic rings, we then focused
on the substituents on the rings. In this study, for quick
exploration, the phenyl ring was chosen because of its synthetic
feasibility. The results are shown in Table 2. It was clear that
substituents containing hydroxyl groups played an important
role in enhancing activities not only for topoisomerase I but
also CTXs. As demonstrated by compounds 22l, 53-55, and
26e, introduction of a hydroxyl group or a hydroxymethyl group
on any position of the phenyl ring resulted in not only
maintenace of the significant CTX activity of unsubstituted
derivative 22a against P388/S and MKN-45 cells but also great
improvement of those against DLD-1 and HeLa cells, which
Results and Discussion
At first, some unsubstituted aromatic rings were explored to
find potent aromatic moieties for the N6-position. The results
are shown in Table 1. Introduction of a phenyl group (22a)
slightly increased the topoisomerase I inhibition both in enzyme
and cells compared to edotecarin (1). Compound 22a also
showed comparable CTXs in P388, MKN-45, DLD-1, and HeLa
cells to those of edotecarin. Encouraged by this result, some
heteroaryl rings were investigated (compounds 22b-k). Most
of the heteroaryl rings showed better in vitro potencies than
edotecarin. Five-membered heteroaryl groups such as 2-furanyl
(22b), 3-furanyl (22c), and 2-pyrrolyl (22d) rings conferred 2-
to 5-fold stronger topoisomerase I inhibitory activities with
almost equipotent CTX activities compared to edotecarin. On
the other hand, introduction of nitrogen-containing six-
membered ring such as pyridine and pyrazine rings resulted in
substantial expansion of CTX windows compared to edotecarin.
In particular, pyridyl derivatives 22e-g dramatically improved
CTX in DLD-1 and HeLa cells, which were resistant to
edotecarin. Topoisomerase I inhibitory activity and CTX activity
of fused heteroaryl derivatives 22i-k were similar to those of
edotecarin.

3228 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 10
Sunami et al.
Scheme 4a
a Reagents and conditions: (i) BocNHNH2, EtOH, 60 °C; (ii) NaBH3CN, 4 N HCl/MeOH, rt; (iii) DIBAL; (iv) NaBH4, MeOH, rt; (v) TFA, CH2Cl2, rt;
(vi) BH3-THF complex, THF, 0 °C then 6 N HCl, rt; (vii) TBDMSCl, imidazole, DMF, rt; (viii) MnO2, CHCl3, rt; (ix) (MeO)3CH, MeOH, reflux; (x) LAH,
THF, rt; (xi) TFA, rt.
Scheme 5a
bazole. The structural model suggested that one of two carbonyl
oxygens of maleimide ring, hydroxyl group of ꢀ-glucose, and
phenol group on the glycosylated indole ring, interacted with
enzyme (Figure 2a). The pyridine ring on N6-position might
occupy space that was created by topoisomerase I and DNA.
The hydroxymethyl moiety might interact with Asp533 (Figure
2b). These newly formed interactions would greatly contribute
a Reagents and conditions: (i) sat. NaHCO3, DMF, 80 °C.
to the significant topoisomerase I inhibitory activity of com-
pound 23c.
were resistant to compound 22a. Conversely, other substituents
such as methyl (26a), nitro (26b), bromo (26c), and cyano (26d)
groups on the 4-position of the phenyl ring caused significant
reduction of not only topoisomerase I inhibitory activity but
Table 4 shows the results of the in vivo anticancer effects of
also CTX activity.
Because potent aromatic rings (Table 1) and substituents on
the ring (Table 2) were identified individually, we then
synthesized and evaluated (hydroxymethyl)pyridyl derivatives,
Some analogues that showed potent inhibition of topo-
isomerase I and CTX activities in vitro were tested for anticancer
effects in mice.
these three compounds. Compound 22m exhibited an anticancer
effect (GID75) comparable to edotecarin (1) against MKN-45
xenografted mice when administered by the same schedule as
that of edotecarin (5 times/week). On the other hand, compounds
22g and 23c showed better antitumor effects than edotecarin,
although the administration number was reduced to twice/week.
All three compounds also showed much stronger antitumor
activity against MX-1 xenografted mice than edotecarin in spite
of the smaller administration number than edotecarin. Although
these compounds showed higher toxicity than edotecarin in some
cases, their safety margins were comparable to that of edotecarin
due to their potent antitumor activities, except for the case of
compound 22m against MKN-45 xenografted mice (safety
margin: >1.2-fold). In addition, these three compounds showed
good selectivities over protein kinase C (PKC) and EGF receptor
kinase (EGFRK) comparable to edotecarin.
Parts a and b of Figure 3 show the tumor growth and
inhibition of compounds 22g, 22m, and 23c against MKN-45
and MX-1 xenografted nude mice, respectively. As summarized
in Figure 3a, tumor regression was observed by administration
of compounds 22g, 22m, and 23c against MKN-45 xenografted
nude mice. Furthermore, Figure 3b shows that treatments of
MX-1 xenografted nude mice by compounds 22m and 23c
which were compounds that combined the best results in Tables
1 and 2. The results are summarized in Table 3 As expected,
most compounds showed potent activities for both topo-
isomerase I and CTX and also the reasonable topoisomerase I
inhibitions in cells except for compound 23b. In particular,
compound 23c, a 4-(2-hydroxymethyl)pyridyl derivative, dem-
onstrated the most potent CTX activity in all four cancer cell
lines. When compared to edotecarin, compound 23c exhibited
not only 10-fold stronger CTX activities in P388 and MKN-45
cells but also 77-fold and 210-fold higher activities in DLD-1
and HeLa cells, respectively.
Docking study of compound 23c with human topoisomerase
I-DNA covalent complex was performed68 to provide the
rational molecular basis for enhancement of the topoisomerase
I inhibitory activity achieved by introduction of (hydroxyl-
methyl)pyridyl moiety on N6-position. Among the all possible
binding mode generated by the docking study, the most similar
one to the experimentally observed binding mode, which was
shown by Stacker et al.,69 was selected. Because of the N6-
substituent, a translational movement of molecule was needed
compared to the binding mode of N6-unsubstituted indolocar-

Topoisomerase I Inhibitors, Analogues of Edotecarin
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 10 3229
Table 1. In Vitro Activities of Unsubstituted Aryl Derivatives
Topo Ia
cleavege EC50
(nM)
K+/SDSb
(P388/S) EC200
(nM)
CTXc
P388/S IC50
(nM)
CTXd
MKN-45 IC50
(nM)
CTXe
DLD-1 IC50
(nM)
CTXf
HeLa IC50
(nM)
Ar
22a
phenyl
25
80
1.8
3.4
100
1300
22b
22c
22d
2-furanyl
3-furanyl
2-pyrrolyl
38
30
30
180
470
6500
1.5
1.3
0.77
5.0
2.8
20
130
130
67
3200
1400
1100
22e
22f
22g
22h
2-pyridyl
3-pyridyl
4-pyridyl
pyrazinyl
30
23
22
35
800
>10000
420
0.59
0.48
0.48
0.60
1.4
18
140
57
24
0.95
0.71
2.8
9.3
3.3
36
210
300
22i
22j
22k
2-quinolyl
3-quinolyl
4-quinolyl
17
30
20
1800
>10000
10000
4.8
5.7
1.8
14
23
1.4
60
290
83
110
77
120
1 (edotecarin)
51
100
1.5
4.8
70
840
a Topoisomerase-mediated DNA cleavage assays were carried out using supercoiled pBR322 plasmid DNA.56 b Effects on the formation of protein-DNA
complex in P388 cells were investigated by the K+/SDS method.56 c CTX against murine leukemia cells (P388) was measured by the colormetric
tetrazolium-formazan method.56 d CTX against human stomach cancer cells (MKN-45) was measured by the colormetric tetrazolium-formazan method
and the sulforhodamine B dye-staining method.56 e CTX against human colon cancer cells (DLD-1). f CTX against human uterine-cervix cells (HeLa).
Table 2. In Vitro Activities of Substituents on Phenyl Ring
Topo I
cleavegeEC50
(nM)
K+/SDS
(P388/S) EC200
(nM)
CTX
P388/S IC50
(nM)
CTX
MKN-45 IC50
(nM)
CTX
DLD-1 IC50
(nM)
CTX
HeLa IC50
(nM)
Ra
H (2,10)
4-Me (1,11)
4-NO2 (1,11)
4-Br (1,11)
22a
26a
26b
26c
26d
22L
53
25
80
1.8
58
21
190
14
1.1
3.4
390
210
1800
85
100
2300
2100
13000
940
18
1300
4200
2700
>50000
650
21
800
>3000
NTb
300
12
>10000
6000
10000
1700
120
4-CN (1,11)
4-OH (2,10)
3.0
4-CH2OH (2,10)
3-OH (2,10)
3-CH2OH (2,10)
2-CH2OH (2,10)
34
20
22
16
600
23
220
24
0.55
0.90
1.2
2.7
4.5
11
0.86
21
21
36
2.6
21
46
21
40
54
55
26e
1.3
a The positions of the two phenol groups are shown in parentheses. b NT: not tested.
resulted in complete responses at doses of 15 and 3 mg/m3,
respectively.
CTX activities in vitro than edotecarin. Among them, the three
most potent pyridylmethyl analogues, compounds 22g, 22m,
and 23c, showed better antitumor activities against MKN-45
human stomach cancer or MX-1 human breast cancer xe-
nografted mice than edotecarin. Furthermore, compounds 22m
and 23c exhibited complete responses against MX-1 cells
Conclusion
A number of 6-arylmethylamino derivatives of edotecarin (1)
were identified as potent topoisomerase I inhibitors, with better

3230 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 10
Table 3. In Vitro Activities of (Hydroxymethyl)pyridyl Derivatives
Sunami et al.
possess a purity of at least 95%. Especially, the purities of
compounds 22g, 22m, and 23c, which were tested in vivo antitumor
effect, were >99%.
implanted in mice. The strategy to introduce arylmethyl groups
at the 6-position successfully achieved both more potent in vitro
activity and in vivo efficacy than edotecarin, and these
compounds may be important for future cancer therapy.
Representative Procedure for the Reduction of Hydrazone.
Procedure 1. 6-(Benzylamino)-2,10-dihydroxy-13-(ꢀ-D-glucopyra-
nosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-
dione (22a). First, 10% HCl/MeOH (3 mL) was added dropwise to
the mixture of compound 21a (25 mg, 0.04 mmol) and sodium
cyanoborohydride (7.6 mg, 0.12 mmol) in MeOH/THF (1:2, 4.5
mL), and after addition, the mixture was stirred at room temperature
for 1 h. The resulting reaction mixture was concentrated under
reduced pressure, and the residue was purified by LH-20 eluting
with MeOH to give compound 22a (18.4 mg, 74%). 1H NMR (300
MHz, DMSO-d6) δ 11.18 (1H, s), 9.76 (1H, s), 9.72 (1H, s), 8.86
(1H, d, J ) 8.4 Hz), 8.78 (1H, d, J ) 8.4 Hz), 7.49 (2H, d, J ) 7.2
Hz), 7.30 (2H, t, J ) 6.9 Hz), 7.23 (1H, td, J ) 5.1, 2.1 Hz), 7.17
(1H, d, J ) 2.1 Hz), 6.97 (1H, d, J ) 2.4 Hz), 6.82 (2H, td, J )
8.4, 2.4 Hz), 6.07 (1H, t, J ) 4.8 Hz), 5.96 (1H, d, J ) 8.1 Hz),
5.84 (1H, t, J ) 3.3 Hz), 5.30 (1H, d, J ) 5.1 Hz), 5.09 (1H, d, J
Experimental Section
1H NMR spectra were recorded on Varian VXR-300 or Varian
MERCURY 400 spectrometers with tetramethylsilane (TMS) as
an internal standard. Specific rotation was measured with a Jasco
DIP-370 polarimeter. Mass spectra (MS) were measured on a JEOL
JMS-SX102A (FAB) or Waters ZQ2000 (ESI) with binary HPLC
pump Waters 1525, or micromass Quattoro II with HP 1100 series
HPLC system. HRMS were measured on a LC (Waters CapLC)-MS
(micromass Q-Tof-2) system (ESI). Analytical HPLC of the
products was recorded on the Waters LC-MS 2690 separations
module system (MS; micromass ZMD (ESI)) using a Waters
ACQUITY UPLC HSS T3 (S-1.8 µm) 2.1 mm × 100 mm column
(gradient as follows: 9-95% acetonitrile (0.1% formic acid)/water
(0.1% formic acid), 0.4 mL/min for 20 min). All tested compounds

Topoisomerase I Inhibitors, Analogues of Edotecarin
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 10 3231
2.4 Hz), 7.33 (1H, dd, J ) 8.1, 5.1 Hz), 7.15 (1H, d, J ) 1.5 Hz),
6.96 (1H, d, J ) 1.5 Hz), 6.80 (2H, td, J ) 8.6, 1.5 Hz), 6.26 (1H,
t, J ) 4.2 Hz), 5.95 (1H, d, J ) 8.1 Hz), 5.88 (1H, brs), 5.38 (1H,
brs), 5.16 (1H, brs), 4.92 (1H, brs), 4.29 (1H, d, J ) 4.5 Hz), 4.02
(1H, d, J ) 10.8 Hz), 3.97-3.85 (2H, m), 3.76 (1H, d, J ) 10.8
Hz), 3.52-3.44 (2H, m).
6-[(2-Furylmethyl)amino]-2,10-dihydroxy-13-(ꢀ-D-glucopyrano-
syl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-
dione (22b). Reduction of compound 21b using procedure 1 gave
compound 22b (53%). 1H NMR (300 MHz, DMSO-d6) δ11.10 (1H,
brs), 10.50-9.20 (2H, brs), 8.82 (1H, d, J ) 8.5 Hz), 8.73 (1H, d,
J ) 8.5 Hz), 7.55 (1H, s), 7.13 (1H, s), 6.95 (1H, d, J ) 2.0 Hz),
6.78-6.74 (3H, m), 6.35-6.31 (2H, m), 6.05 (1H, t, J ) 5.1 Hz),
5.94 (1H, d, J ) 8.3 Hz), 5.82 (1H, brs), 5.50-4.83 (3H, brs),
4.00 (2H, d, J ) 10.0 Hz), 3.95-3.85 (2H, m), 3.76 (1H, d, J )
10.0 Hz), 3.50 (2H, d, J ) 9.2 Hz).
6-[(3-Furylmethyl)amino]-2,10-dihydroxy-13-(ꢀ-D-glucopyrano-
syl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-
dione (22c). Reduction of compound 21c using procedure 1 gave
1
compound 22c (77%). H NMR (300 MHz, DMSO-d6) δ 11.18
(1H, s), 10.89 (2H, brs), 8.85 (1H, d, J ) 8.5 Hz), 8.77 (1H, d, J
) 8.5 Hz), 7.62 (1H, s), 7.56 (1H, t, J ) 1.0 Hz), 7.16 (1H, s),
6.97 (1H, d, J ) 1.9 Hz), 6.80 (2H, td, J ) 8.9, 1.9 Hz), 6.57 (1H,
s), 5.99-5.94 (2H, m), 5.86 (1H, brs), 5.34 (1H, brs), 5.12 (1H,
brs), 4.91 (1H, brs), 4.11 (2H, d, J ) 4.6 Hz), 4.01 (1H, d, J )
10.2 Hz), 3.95-3.87 (2H, m), 3.78 (1H, d, J ) 10.2 Hz), 3.50
(2H, brs).
2,10-Dihydroxy-6-[(1H-pyrrol-2-ylmethyl)amino]-13-(ꢀ-D-glu-
copyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carba-
zole-5,7(6H)-dione (22d). Reduction of compound 21d using
procedure 1 gave compound 22d (43%). 1H NMR (300 MHz,
DMSO-d6) δ 11.17 (1H, s), 10.73 (1H, s), 9.79 (2H, brs), 8.85
(1H, d, J ) 8.5 Hz), 8.77 (1H, d, J ) 8.5 Hz), 7.16 (1H, s), 6.97
(1H, d, J ) 1.9 Hz), 6.80 (2H, td, J ) 8.9, 1.9 Hz), 6.64 (1H, s),
5.97-5.80 (4H, m), 5.38 (1H, brs), 5.15 (1H, brs), 4.91 (1H, brs),
4.17 (2H, d, J ) 5.1 Hz), 4.12-3.75 (5H, m), 3.52-3.49 (2H, m).
2,10-Dihydroxy-6-[(pyridin-4-ylmethyl)amino]-13-(ꢀ-D-glucopy-
ranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-
5,7(6H)-dione (22g). Reduction of compound 21g using procedure
Figure 2. (a) Predicted binding mode of compound 23c (blue) in the
topoisomerase I-DNA covalent complex. Side chains of amino acids
which could interact with compound are diagrammed, and important
hydrogen bonds are indicated with green lines. (b) Surface of topoi-
somerase I (green)-DNA (gold) covalent complex, showing pyridine
ring on N6-position of compound 23c occupied the space created by
topoisomerase I and DNA.
) 3.3 Hz), 4.90 (1H, d, J ) 3.3 Hz), 4.26 (2H, d, J ) 4.8 Hz),
4.02 (1H, dd, J ) 11.7, 4.2 Hz), 3.96-3.86 (2H, m), 3.78 (1H, dd,
J ) 8.1, 4.2 Hz), 3.53-3.46 (2H, m).
1
3 gave compound 22g (14%). H NMR (300 MHz, DMSO-d6) δ
11.16 (1H, s), 9.85 (2H, brs), 8.83 (1H, d, J ) 8.5 Hz), 8.75 (1H,
d, J ) 8.5 Hz), 8.626 (1H, d, J ) 2.4 Hz),8.41 (1H, dd, J ) 5.1,
1.8 Hz), 7.92 (1H, td, J ) 8.1, 2.4 Hz), 7.33 (1H, dd, J ) 8.1, 5.1
Hz), 7.15 (1H, d, J ) 1.5 Hz), 6.96 (1H, d, J ) 1.5 Hz), 6.80 (2H,
td, J ) 8.6, 1.5 Hz), 6.26 (1H, t, J ) 4.2 Hz), 5.95 (1H, d, J ) 8.1
Hz), 5.88 (1H, brs), 5.38 (1H, brs), 5.16 (1H, brs), 4.92 (1H, brs),
4.29 (2H, d, J ) 4.5 Hz), 4.02 (1H, d, J ) 10.8 Hz), 3.97-3.85
Representative Procedure for the Reduction of Hydrazone.
Procedure 2. 2,10-Dihydroxy-6-[(pyridin-2-ylmethyl)amino]-13-
(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-
c]carbazole-5,7(6H)-dione (22e). The mixture of compound 21e (20
mg, 0.032 mmol), sodium cyanoborohydride (80 mg, 1.3 mmol),
and zinc chloride (1.0 M in diethyl ether, 0.64 mL) in THF (5 mL)
was stirred at room temperature for 18 h. The resulting reaction
mixture was concentrated under reduced pressure, and the residue
was purified by LH-20 eluting with MeOH to give compound 22e
(10.5 mg, 53%). 1H NMR (300 MHz, DMSO-d6) δ 11.19 (1H, s),
9.78 (2H, brs), 8.85 (1H, d, J ) 8.5 Hz), 8.76 (1H, d, J ) 8.5 Hz),
8.41 (1H, d, J ) 4.4 Hz), 7.82-7.75 (2H, m), 7.26-7.20 (2H, m),
7.17 (1H, d, J ) 2.1 Hz), 6.98 (1H, d, J ) 2.1 Hz), 6.80 (2H, td,
J ) 8.6, 2.1 Hz), 6.25 (1H, t, J ) 4.5 Hz), 5.96 (1H, d, J ) 8.1
Hz), 5.86 (1H, s), 5.38 (1H, brs), 5.15 (1H, brs), 4.91 (1H, brs),
4.36 (2H, d, J ) 4.8 Hz), 4.00 (1H, d, J ) 10.5 Hz), 3.95-3.84
(2H, m), 3.78 (1H, d, J ) 10.5 Hz), 3.55-3.46 (2H, m).
Representative Procedure for the Reduction of Hydrazone.
Procedure 3. 2,10-Dihydroxy-6-[(pyridin-3-ylmethyl)amino]-13-
(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-
c]carbazole-5,7(6H)-dione (22f). The mixture of compound 21f (25
mg, 0.040 mmol) and 5% palladium on carbon (10 mg) in MeOH/
THF (1:1, 5 mL) was equipped with a balloon of hydrogen gas
and stirred at room temperature. After the reaction was over, the
mixture was filtered through a pack of celite. The filtrate was
concentrated under reduced pressure, and the residue was purified
by LH-20 eluting with MeOH to give compound 22f (3.5 mg, 14%).
1H NMR (300 MHz, DMSO-d6) δ 11.16 (1H, s), 9.85 (2H, brs),
8.83 (1H, d, J ) 8.5 Hz), 8.75 (1H, d, J ) 8.5 Hz), 8.62 (1H, d,
J ) 2.4 Hz), 8.41 (1H, dd, J ) 5.1, 1.8 Hz), 7.92 (1H, td, J ) 8.1,
(2H, m), 3.76 (1H, d, J ) 10.8 Hz), 3.52-3.44 (2H, m); [R]26
D
163.9 (c 1.02, DMSO). Anal. (C32H27N5O9 ·H2O) C, H, N.
2,10-Dihydroxy-6-[(pyrazin-2-ylmethyl)amino]-13-(ꢀ-D-glucopy-
ranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-
5,7(6H)-dione (22h). Reduction of compound 21h using procedure
1
3 gave compound 22h (35%). H NMR (300 MHz, DMSO-d6) δ
11.16 (1H, s), 9.85 (2H, brs), 8.83 (1H, d, J ) 8.5 Hz), 8.75 (1H,
d, J ) 8.5 Hz), 8.62-8.58 (2H, m), 8.41 (1H, d, J ) 5.1 Hz), 7.15
(1H, d, J ) 1.5 Hz), 6.96 (1H, d, J ) 1.5 Hz), 6.80 (2H, td, J )
8.6, 1.5 Hz), 6.26 (1H, t, J ) 4.2 Hz), 5.95 (1H, d, J ) 8.1 Hz),
5.88 (1H, brs), 5.38 (1H, brs), 5.16 (1H, brs), 4.92 (1H, brs), 4.29
(2H, d, J ) 4.5 Hz), 4.02 (1H, d, J ) 10.8 Hz), 3.97-3.85 (2H,
m), 3.76 (1H, d, J ) 10.8 Hz), 3.52-3.44 (2H, m).
2,10-Dihydroxy-6-[(quinolin-2-ylmethyl)amino]-13-(ꢀ-D-glucopy-
ranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-
5,7(6H)-dione (22i). Reduction of compound 21i using procedure
1
2 gave compound 22i (25%). H NMR (300 MHz, DMSO-d6) δ
11.18 (1H, s), 9.78 (1H, s), 9.75 (1H, s), 8.83 (1H, d, J ) 8.5 Hz),
8.75 (1H, d, J ) 8.5 Hz), 8.39 (1H, d, J ) 8.6 Hz), 7.99 (1H, d,
J ) 8.6 Hz), 7.93 (1H, d, J ) 8.6 Hz), 7.87 (1H, d, J ) 8.6 Hz),
7.65 (1H, t, J ) 8.6 Hz), 7.52 (1H, t, J ) 8.6 Hz), 7.17 (1H, d, J
) 1.5 Hz), 6.96 (1H, d, J ) 1.5 Hz), 6.80 (2H, td, J ) 8.6, 1.5
Hz), 6.41 (1H, t, J ) 4.8 Hz), 5.95 (1H, d, J ) 8.7 Hz), 5.86 (1H,
t, J ) 3.9 Hz), 5.33 (1H, d, J ) 3.9 Hz), 5.10 (1H, d, J ) 3.9 Hz),

3232 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 10
Sunami et al.
Table 4. Biological Profiles of Compounds 22g, 22m, 23c, and Edotecarin
a The Histon II-As was used as a substrate for protein kinase C.56 b Poly(Glu4Tyr1) was used as a substrate for EGF receptor kinase.56 c GID75: approximate
75% growth inhibition dose reflects the anticancer effect on MKN-45 or MX-1 (human breast cancer) cells implanted subcutaneously into a side flank of
nude mice. d LD10: approximate 10% lethal dose at the treatment schedule. e Safety margin: the ratio LD10/GID75. f Compounds were injected iv twice/week
for two consecutive weeks, and treatment was initiated when tumors grew to 0.2 cm3 or larger. These compounds showed wider safety margins by intermitted
administration (twice/week) than by consecutive administration (five times/week). g Compounds were injected iv Five times/week for two consecutive weeks,
and treatment was initiated when tumors grew to 0.2 cm3 or larger.
4.88 (1H, d, J ) 3.9 Hz), 4.56 (2H, d, J ) 4.8 Hz), 4.02-3.98
(1H, m), 3.93-3.85 (2H, m), 3.80-3.72 (1H, m), 3.52-3.45 (2H,
m).
5.10 (1H, d, J ) 4.8 Hz), 4.91 (1H, d, J ) 4.8 Hz), 4.12 (2H, d,
J ) 4.8 Hz), 4.07-3.95 (1H, m), 3.91 (2H, s), 3.82-3.75 (1H, m),
3.55-3.46 (2H, m).
2,10-Dihydroxy-6-[(quinolin-3-ylmethyl)amino]-13-(ꢀ-D-glucopy-
ranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-
5,7(6H)-dione (22j). Reduction of compound 21j using procedure
2,10-Dihydroxy-6-({[6-(hydroxymethyl)pyridin-2-yl]methyl}amino)-
13-(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-
c]carbazole-5,7(6H)-dione (22m). Reduction of compound 21m using
1
1
2 gave compound 22j (33%). H NMR (300 MHz, DMSO-d6) δ
procedure 2 gave compound 22m (40%). H NMR (400 MHz,
11.16 (1H, s), 9.75 (2H, brs), 9.08 (1H, d, J ) 1.9 Hz), 8.82 (1H,
d, J ) 8.6 Hz), 8.74 (1H, d, J ) 8.6 Hz), 8.37 (1H, d, J ) 1.9 Hz),
7.97 (1H, d, J ) 8.7 Hz), 7.91 (1H, d, J ) 8.7 Hz), 7.68 (1H, t, J
) 8.7 Hz), 7.54 (1H, t, J ) 8.7 Hz), 7.15 (1H, d, J ) 2.1 Hz), 6.96
(1H, d, J ) 2.1 Hz), 6.80 (2H, td, J ) 8.6, 2.1 Hz), 6.37 (1H, t, J
) 4.2 Hz), 5.94 (1H, d, J ) 8.1 Hz), 5.86 (1H, brs), 5.34 (1H,
brs), 5.11 (1H, brs), 4.88 (1H, brs), 4.48 (2H, d, J ) 4.2 Hz), 4.01
(1H, d, J ) 10.3 Hz), 3.89 (2H, brs), 3.76 (1H, d, J ) 10.3 Hz),
3.52-3.45 (2H, m).
DMSO-d6) δ: 11.19 (1H, s), 9.80 (2H, brs), 8.85 (1H, d, J ) 8.3
Hz), 8.77 (1H, d, J ) 8.3 Hz), 7.80 (1H, t, J ) 7.6 Hz), 7.64 (1H,
d, J ) 7.6 Hz), 7.31 (1H, d, J ) 7.6 Hz), 7.17 (1H, d, J ) 2.1 Hz),
6.98 (1H, d, J ) 2.1 Hz), 6.82 (2H, td, J ) 8.3, 2.1 Hz), 6.22 (1H,
t, J ) 5.1 Hz), 5.97 (1H, d, J ) 8.3 Hz), 5.88 (1H, brs), 5.35 (1H,
brs), 5.30 (1H, brs), 5.13 (1H, brs), 4.91 (1H, d, J ) 3.4 Hz), 4.43
(2H, s), 4.34 (2H, d, J ) 5.1 Hz), 4.01 (1H, d, J ) 10.2 Hz),
3.94-3.88 (2H, m), 3.78 (1H, d, J ) 10.2 Hz), 3.53-3.45 (2H,
m); [R]26 151.1 (c 0.92, DMSO). Anal. (C33H29N5O10 · 2H2O ·
D
2,10-Dihydroxy-6-[(quinolin-4-ylmethyl)amino]-13-(ꢀ-D-glucopy-
ranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-
5,7(6H)-dione (22k). Reduction of compound 21k using procedure
MeOH) C, H, N.
6-({[5-({[tert-Butyl(dimethyl)silyl]oxy}methyl)pyridin-2-
yl]methyl}amino)-2,10-dihydroxy-13-(ꢀ-D-glucopyranosyl)-12,13-dihy-
dro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (22n). Re-
duction of compound 21n using procedure 2 gave compound 22n,
which was used for the next reaction without further purification.
1H NMR (300 MHz, DMSO-d6) δ: 11.18 (1H, s), 9.78 (2H, brs),
8.82 (1H, d, J ) 8.3 Hz), 8.76 (1H, d, J ) 8.3 Hz), 8.27 (1H, s),
7.75 (1H, t, J ) 5.2 Hz), 7.70 (1H, d, J ) 5.2 Hz), 7.17 (1H, d, J
) 2.1 Hz), 6.98 (1H, d, J ) 2.1 Hz), 6.80 (3H, td, J ) 8.3, 2.1
Hz), 6.21 (1H, t, J ) 4.9 Hz), 5.95 (1H, d, J ) 8.3 Hz), 5.90 (1H,
brs), 5.38 (1H, brs), 5.12 (1H, brs), 4.90 (1H, brs), 4.68 (2H, s),
4.35 (1H, d, J ) 4.9 Hz), 4.08 (1H, brs), 4.01 (1H, d, J ) 10.2
Hz), 3.89 (2H, s), 3.78 (1H, d, J ) 10.2 Hz), 3.49 (2H, brs), 0.82
(9H, s), 0.03 (6H, s). MS (FAB) m/z 766 (M + H)+.
Representative Procedure for the Removal of tert-butyl(di-
methyl)silyl group. Procedure 4. 2,10-Dihydroxy-6-({[5-(hydroxy-
methyl)pyridin-2-yl]methyl}amino)-13-(ꢀ-D-glucopyranosyl)-12,13-
dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (23a).
A mixture of compound 22n (15.3 mg) and tetrabutylammonium
fluoride (1.0 M in THF, 1 mL, 1 mmol) in THF (2 mL) was stirred
1
3 gave compound 22k (35%). H NMR (300 MHz, DMSO-d6) δ
11.13 (1H, brs), 8.86 (1H, d, J ) 4.2 Hz), 8.85 (1H, d, J ) 8.7
Hz), 8.76 (1H, d, J ) 8.7 Hz), 8.50 (1H, d, J ) 8.1 Hz), 8.03 (1H,
d, J ) 8.1 Hz), 7.79 (1H, d, J ) 4.2 Hz), 7.76 (1H, t, J ) 8.1 Hz),
7.69 (1H, t, J ) 8.1 Hz), 7.12 (1H, d, J ) 2.1 Hz), 6.93 (1H, d, J
) 2.1 Hz), 6.78 (2H, td, J ) 8.6, 2.1 Hz), 6.33 (1H, t, J ) 4.2 Hz),
5.92 (1H, d, J ) 8.5 Hz), 5.40-4.95 (3H, brs), 4.76 (2H, d, J )
4.2 Hz), 4.02 (1H, d, J ) 10.3 Hz), 3.95-3.86 (2H, m), 3.77 (1H,
d, J ) 10.3 Hz), 3.52-3.45 (2H, m).
2,10-Dihydroxy-6-[(4-hydroxybenzyl)amino]-13-(ꢀ-D-glucopyra-
nosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-
dione (22l). Reduction of compound 21l using procedure 1 gave
compound 22l (86%). 1H NMR (300 MHz, DMSO-d6) δ 11.17 (1H,
s), 9.77 (1H, s), 9.74 (1H, s), 9.24 (1H, s), 8.86 (1H, d, J ) 8.4
Hz), 8.78 (1H, d, J ) 8.4 Hz), 7.25 (2H, d, J ) 8.7 Hz), 7.17 (2H,
d, J ) 1.8 Hz), 6.97 (1H, d, J ) 1.8 Hz), 6.83(1H, td, J ) 8.7, 1.8
Hz), 6.67 (2H, d, J ) 8.7 Hz), 5.96 (1H, d, J ) 8.1 Hz), 5.87 (1H,
t, J ) 4.8 Hz), 5.85 (1H, t, J ) 3.9 Hz), 5.32 (1H, d, J ) 4.5 Hz),

Topoisomerase I Inhibitors, Analogues of Edotecarin
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 10 3233
Figure 3. (a) Tumor growth and inhibition of compounds 22g, 22m, and 23c against MKN-45 xenografted nude mice. (b) Tumor growth and
inhibition of compounds 22g, 22m, and 23c against MX-1 xenografted nude mice.
at room temperature for 1.0 h. The mixture was concentrated under
reduced pressure, and the residue was purified by LC-20 eluting
with MeOH to give compound 23a (31%). H NMR (300 MHz,
DMSO-d6) δ 11.18 (1H, s), 9.77 (2H, brs), 8.82 (1H, d, J ) 9.0
Hz), 8.74 (1H, d, J ) 9.0 Hz), 8.27 (1H, dd, J ) 5.1, 1.8 Hz), 7.83
(1H, d, J ) 8.1 Hz), 7.28 (1H, dd, J ) 8.1, 5.1 Hz), 7.17 (1H, d,
J ) 1.8 Hz), 6.98 (1H, d, J ) 1.8 Hz), 6.81 (2H, td, J ) 8.5, 1.8
Hz), 6.15 (1H, t, J ) 5.1 Hz), 5.97 (1H, d, J ) 8.1 Hz), 5.86 (1H,
t, J ) 4.2 Hz), 5.33 (1H, d, J ) 5.4 Hz), 5.31 (1H, d, J ) 5.4 Hz),
5.12 (1H, d, J ) 4.8 Hz), 4.93(1H, d, J ) 4.2 Hz), 4.87 (2H, d, J
) 5.1 Hz), 4.33 (2H, d, J ) 4.2 Hz), 4.05-3.96 (1H, m), 3.91
(2H, s), 3.82-3.75 (1H, m), 3.58-3.46 (2H, m).
6-({[4-({[tert-Butyl(dimethyl)silyl]oxy}methyl)pyridin-3-
yl]methyl}amino)-2,10-dihydroxy-13-(ꢀ-D-glucopyranosyl)-12,13-dihy-
dro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (22q). Re-
duction of compound 21q using procedure 3 gave compound 22q,
which was used for the next reaction without further purification.
This product was characterized by MS analysis. MS (FAB) m/z
766 (M + H)+.
1
DMSO-d6) δ: 11.18 (1H, s), 9.77 (2H, brs), 8.84 (1H, d, J ) 8.5
Hz), 8.76 (1H, d, J ) 8.5 Hz), 8.35 (1H, d, J ) 1.7 Hz), 7.72 (2H,
s), 7.17 (1H, d, J ) 1.7 Hz), 6.98 (1H, d, J ) 1.7 Hz), 6.80 (3H,
td, J ) 8.3, 1.7 Hz), 6.22 (1H, t, J ) 4.6 Hz), 5.96 (1H, d, J ) 8.9
Hz), 5.87 (1H, brs), 5.35 (1H, brs), 5.22 (1H, t, J ) 4.6 Hz),
5.11(1H, brs), 4.91 (1H, s), 4.46 (2H, d, J ) 4.6 Hz), 4.35 (1H, d,
J ) 4.6 Hz), 4.01 (1H, d, J ) 10.2 Hz), 3.91 (2H, s), 3.78 (1H, d,
J ) 10.2 Hz), 3.49 (2H, brs).
2,10-Dihydroxy-6-({[4-(hydroxymethyl)pyridin-2-yl]methyl}amino)-
13-(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-
c]carbazole-5,7(6H)-dione (22o). Reduction of compound 21o using
procedure 2 gave compound 22o (51%). 1H NMR (300 MHz,
DMSO-d6) δ 11.19 (1H, s), 9.78 (1H, s), 9.75 (1H, s), 8.85 (1H, d,
J ) 8.5 Hz), 8.77 (1H, d, J ) 8.5 Hz), 8.36 (1H, d, J ) 5.0 Hz),
7.67 (1H, s), 7.19 (1H, d, J ) 5.0 Hz), 7.18 (1H, s), 6.98 (1H,s),
6.81 (2H, t, J ) 8.5 Hz), 6.18 (1H, t, J ) 4.8 Hz), 5.97 (1H, d, J
) 8.1 Hz), 5.87 (1H, t, J ) 4.0 Hz), 5.44 (1H, t, J ) 5.6 Hz), 5.34
(1H, d, J ) 3.5 Hz), 5.12 (1H, d, J ) 4.3 Hz), 4.92 (1H, d, J ) 4.3
Hz), 4.56 (2H, d, J ) 5.6 Hz), 4.33 (2H, d, J ) 4.8 Hz), 4.06-3.71
(4H, m), 3.58-3.46 (2H, m).
2,10-Dihydroxy-6-({[4-(hydroxymethyl)pyridin-3-yl]methyl}amino)-
13-(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-
c]carbazole-5,7(6H)-dione (23b). Removal of TBDMS group of
1
compound 22q using procedure 4 gave compound 23b (25%). H
NMR (300 MHz, DMSO-d6) δ 11.18 (1H, s), 9.75 (1H, s), 9.73
(1H, s), 8.84 (1H, d, J ) 8.4 Hz), 8.77 (1H, d, J ) 8.4 Hz), 8.42
(1H, d, J ) 4.9 Hz), 8.39 (1H, s), 8.48 (1H, d, J ) 4.9 Hz), 7.17
(1H, d, J ) 1.7 Hz), 6.97 (1H, d, J ) 1.8 Hz), 6.81 (2H, td, J )
8.5, 1.7 Hz), 6.09 (1H, t, J ) 4.7 Hz), 5.97 (1H, d, J ) 8.1 Hz),
5.84 (1H, t, J ) 3.8 Hz), 5.39 (1H, t, J ) 5.8 Hz), 5.30 (1H, d, J
) 4.8 Hz), 5.09 (1H, d, J ) 4.2 Hz), 4.95 (2H, d, J ) 5.8 Hz),
2,10-Dihydroxy-6-({[3-(hydroxymethyl)pyridin-2-yl]methyl}amino)-
13-(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-
c]carbazole-5,7(6H)-dione (22p). Reduction of compound 21p using
procedure 1 gave compound 22p (68%). 1H NMR (300 MHz,

3234 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 10
Sunami et al.
4.90 (1H, d, J ) 3.3 Hz), 4.27 (2H, d, J ) 4.7 Hz), 4.03-3.75
(4H, m), 3.52-3.47 (2H, m).
2,10-Dihydroxy-6-[(4-cyanobenzyl)amino]-13-(ꢀ-D-glucopyrano-
syl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-
dione (26d). Compound 26d was prepared in a similar manner to
the synthesis of compound 26a by substituting 4-cyanobenzylbro-
6-({[3-({[tert-Butyl(dimethyl)silyl]oxy}methyl)pyridin-4-
yl]methyl}amino)-2,10-dihydroxy-13-(ꢀ-D-glucopyranosyl)-12,13-
dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (22r).
Reduction of compound 21r using procedure 3 gave compound
22r, which was used for the next reaction without further purifica-
1
mide 25d with compound 25a in 30% yield. H NMR (300 MHz,
DMSO-d6) δ 10.89 (1H, s), 10.35 (1H, s), 9.95 (1H, s), 8.68 (1H,
d, J ) 8.0 Hz), 8.50 (1H, d, J ) 8.0 Hz), 7.81-7.74 (4H, m), 7.16
(2H, t, J ) 8.0 Hz), 7.18-6.98 (2H, m), 6.36 (1H, t, J ) 3.5 Hz),
5.40 (1H, d, J ) 5.6 Hz), 5.32 (1H, t, J ) 5.4 Hz), 5.19 (1H, d, J
) 5.3 Hz), 4.85 (1H, d, J ) 5.4 Hz), 4.39 (2H, s), 4.10-3.90 (2H,
m), 3.77-3.51 (3H, m), 3.41 -3.2 5 (2H, m).
2,10-Dihydroxy-6-{[2-(hydroxymethyl)benzyl]amino}-13-(ꢀ-D-
glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]car-
bazole-5,7(6H)-dione (26e). Compound 26e was prepared in a
similar manner to the synthesis of compound 26a by substituting
2-(hydroxymethyl)benzylbromide 25e and compound 19 with
compounds 25a and 24 in 12% yield. 1H NMR (300 MHz, DMSO-
d6) δ: 11.19 (1H, s), 9.78 (1H, s), 9.75 (1H, s), 8.85 (1H, d, J )
8.6 Hz), 8.78 (1H, d, J ) 8.6 Hz), 7.44 (1H, d, J ) 7.2 Hz), 7.37
(1H, d, J ) 7.2 Hz), 7.23 (1H, t, J ) 7.2 Hz), 7.18 (2H, s), 6.98
(1H, s), 6.81 (2H, d, J ) 8.8 Hz), 6.05-5.95 (2H, m), 5.85 (1H,
brs), 5.33 (1H, d, J ) 3.2 Hz), 5.17-5.10 (2H, m), 4.92 (1H, d, J
) 4.0 Hz), 4.82 (2H, d, J ) 5.2 Hz), 4.28 (2H, d, J ) 5.2 Hz),
4.10-3.72 (4H, m), 3.55-3.45 (2H, m).
1
tion. H NMR (300 MHz, CD3OD) δ: 8.93 (1H, d, J ) 8.3 Hz),
8.79 (1H, d, J ) 8.3 Hz), 8.52 (1H, s), 8.37 (1H, t, J ) 5.1 Hz),
7.62 (1H, d, J ) 5.1 Hz), 7.09 (1H, d, J ) 2.1 Hz), 6.98 (1H, d,
J ) 2.1 Hz), 6.78 (3H, td, J ) 8.3, 2.1 Hz), 5.94 (1H, d, J ) 8.3
Hz), 5.10 (2H, s), 4.40 (2H, s), 4.25-4.17 (2H, m), 4.01-3.90
(2H, m), 3.85-3.67 (2H, m), 0.93 (9H, s), 0.18 (6H, s); MS (FAB)
m/z 766 (M + H)+.
2,10-Dihydroxy-6-({[3-(hydroxymethyl)pyridin-4-yl]methyl}amino)-
13-(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-
c]carbazole-5,7(6H)-dione (23c). Removal of TBDMS group of
1
compound 22r using procedure 4 gave compound 23c (49%). H
NMR (300 MHz, DMSO-d6) δ: 11.19 (1H, s), 9.78 (1H, s), 9.75
(1H, s), 8.85 (1H, d, J ) 9.1 Hz), 8.77 (1H, d, J ) 9.1 Hz), 8.51
(1H, s), 8.11 (1H, d, J ) 5.1 Hz), 7.59 (1H, d, J ) 5.1 Hz), 7.17
(1H, d, J ) 2.1 Hz), 6.97 (1H, d, J ) 2.1 Hz), 6.81 (2H, td, J )
8.8, 2.1 Hz), 6.25 (1H, t, J ) 4.9 Hz), 5.98 (1H, d, J ) 8.6 Hz),
5.86 (1H, t, J ) 4.0 Hz), 5.32 (1H, d, J ) 4.4 Hz), 5.23 (1H, t, J
) 5.6 Hz), 5.11 (1H, d, J ) 4.4 Hz), 4.91 (1H, d, J ) 4.4 Hz),
4.74 (2H, d, J ) 5.6 Hz), 4.35 (2H, d, J ) 4.9 Hz), 4.01(1H, d, J
) 10.6 Hz), 3.96 -3.85 (2H, m), 3.77 (1H, d, J ) 10.6 Hz),
Representative Procedure for the Reaction of Compound 51
with Arylmethylhydrazines. 2,10-Dihydroxy-6-{[4-(hydroxymeth-
yl)benzyl]amino}-13-(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indo-
lo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (53). A mixture of
compound 51 (100 mg, 0.19 mmol), [4-(hydrazinomethyl)phenyl-
]methanol hydrochloride 52a (100 mg, 0.53 mmol) in DMF (5 mL),
and sat. aqueous NaHCO3 solution (1 mL) was stirred at 80 °C for
0.5 h. The resulting reaction mixture was partitioned between methyl
ethyl ketone and water. The organic layer was washed with brine,
dried over Na2SO4, and concentrated under reduced pressure. The
residue was purified by LH-20 eluting with MeOH to give
3.54-3.46 (2H, m); [R]26 141.5 (c 0.86, DMSO). Anal.
D
(C33H29N5O10 ·2H2O·MeOH) C, H, N.
Representative Procedure for the Reaction of Compounds 19
or 24 with Arylmethylbromides. 2,10-Dihydroxy-6-[(4-methylben-
zyl)amino]-13-(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-
a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (26a). A mixture of com-
pound 24 (50 mg, 0.094 mmol) and 4-methylbenzylbromide (200
mg, 1.09 mmol) in DMF (1 mL) was stirred at room temperature
for 3 h. The resulting reaction mixture was partitioned between
ethyl acetate and water. The organic layer was washed with brine,
dried over Na2SO4, and concentrated under reduced pressure. The
residue was purified by LH-20 eluting with MeOH to give
1
compound 53 (33 mg, 27%). H NMR (300 MHz, DMSO-d6) δ:
11.10 (1H, brs), 8.83 (1H, d, J ) 8.4 Hz), 8.73 (1H, d, J ) 8.4
Hz), 7.44 (2H, d, J ) 8.4 Hz), 7.23 (2H, d, J ) 8.4 Hz), 7.11 (1H,
s), 6.94 (1H, s), 6.78 (2H, td, J ) 9.0, 2.1 Hz), 6.02 (1H, t, J ) 4.8
Hz), 5.92 (1H, d, J ) 8.1 Hz), 5.23-4.80 (2H, m), 4.43 (2H, s),
4.24 (2H, s), 3.71-4.06 (4H, m), 3.54-3.45 (2H, m), 3.42 -3.25
(3H, m).
1
compound 26a (14 mg, 23%). H NMR (300 MHz, DMSO-d6) δ
10.90 (1H, s), 10.36 (1H, s), 9.96 (1H, s), 8.70 (1H, d, J ) 7.8
Hz), 8.53 (1H, d, J ) 7.8 Hz), 7.40 (2H, d, J ) 8.1 Hz), 7.20 (2H,
td, J ) 7.8, 1.5 Hz), 7.15 (2H, d, J ) 9.6 Hz), 7.19-6.98 (1H,m),
7.03 (2H, td, J ) 7.8, 1.5 Hz), 6.08 (1H, brs), 5.51-5.36 (2H, m),
4.88 (1H, brs), 4.24 (2H, s), 4.10-3.96 (2H, m), 3.80-3.57 (3H,
m), 3.50-3.40 (2H, m), 2.25 (3H, s).
2,10-Dihydroxy-6-[(4-nitrolbenzyl)amino]-13-(ꢀ-D-glucopyrano-
syl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-
dione (26b). Compound 26b was prepared in a similar manner to
the synthesis of compound 26a by substituting 4-nitrobenzylbromide
25b with compound 25a in 30% yield. 1H NMR (300 MHz, DMSO-
d6) δ 10.89 (1H, s), 10.34 (1H, s), 9.95 (1H, s), 8.68 (1H, d, J )
7.8 Hz), 8.50 (1H, d, J ) 7.8 Hz), 8.18 (2H, d, J ) 9.0 Hz), 7.84
(2H, d, J ) 9.0 Hz), 7.18 (2H, t, J ) 8.1 Hz), 7.00 (2H, t, J ) 8.1
Hz), 6.42 (1H, brs), 5.45 -5.33 (2H, m), 5.23 (1H, brs), 4.87 (1H,
d, J ) 5.4 Hz), 4.45 (2H, s), 4.10-3.96 (2H, m), 3.80-3.56 (3H,
m), 3.50-3.40 (2H, m).
2,10-Dihydroxy-6-[(3-hydroxybenzyl)amino]-13-(ꢀ-D-glucopyra-
nosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-
dione (54). Compound 54 was prepared in a similar manner to the
synthesis of compound 53 by substituting 3-(hydrazinomethyl)phe-
nol hydrochloride 52b with compound 52a in 37% yield. 1H NMR
(300 MHz, DMSO-d6) δ: 11.18 (1H, s), 9.76 (1H, s), 9.73 (1H, s),
9.28 (1H, s), 8.87 (1H, d, J ) 8.5 Hz), 8.79 (1H, d, J ) 8.5 Hz),
7.17 (1H, s), 7.08 (1H, dd, J ) 8.0, 7.5 Hz), 6.97 (1H, d, J ) 2.3
Hz), 6.93-6.78 (4H, m), 6.60 (1H, dd, J ) 8.0, 1.5 Hz), 5.98-5.95
(2H, m), 5.87-5.81 (1H, m), 5.30 (1H, d, J ) 4.2 Hz), 5.09 (1H,
d, J ) 4.9 Hz), 4.90 (1H, d, J ) 5.1 Hz), 4.15 (2H, s), 4.05-3.72
(4H, m), 3.51-3.47 (2H, m).
2,10-Dihydroxy-6-{[3-(hydroxymethyl)benzyl]amino}-13-(ꢀ-D-
glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]car-
bazole-5,7(6H)-dione (55). Compound 55 was prepared in a similar
manner to the synthesis of compound 53 by substituting [3-(hydrazi-
nomethyl)phenyl]methanol hydrochloride 32 with compound 52a in
1
37% yield. H NMR (300 MHz, DMSO-d6) δ: 11.18 (1H, s), 8.86
2,10-Dihydroxy-6-[(4-bromobenzyl)amino]-13-(ꢀ-D-glucopyra-
nosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-
dione (26c). Compound 26c was prepared in a similar manner to
the synthesis of compound 26a by substituting 4-bromobenzylbro-
(1H, d, J ) 8.4 Hz), 8.78 (1H, d, J ) 8.4 Hz), 7.42 (1H, s), 7.40 (1H,
d, J ) 7.5 Hz), 7.27 (1H, t, J ) 7.5 Hz), 7.18 (1H, d, J ) 7.5 Hz),
7.20-7.15 (1H, m), 6.98 (1H, d, J ) 1.8 Hz), 6.81 (2H, td, J ) 8.1,
1.8 Hz), 6.00 (1H, t, J ) 4.8 Hz), 5.95 (1H, d, J ) 8.7 Hz), 5.43 (1H,
brs), 5.16 (2H, brs), 4.93 (1H, brs), 4.47 (2H, s), 4.25 (2H, d, J ) 4.8
Hz), 4.10 (1H, brs), 4.02 (1H, d, J ) 10.8 Hz), 4.00-3.85 (2H, m),
3.85-3.70 (1H, m), 3.50-3.40 (2H, m).
1
mide 25c with compound 25a in 18% yield. H NMR (300 MHz,
DMSO-d6) δ 10.89 (1H, s), 10.34 (1H, s), 9.95 (1H, s), 8.68 (1H,
d, J ) 7.8 Hz), 8.50 (1H, d, J ) 7.8 Hz), 7.49 (4H, s), 7.18 (2H,
t, J ) 7.8 Hz), 7.00 (2H, t, J ) 7.8 Hz), 6.22 (1H, t, J ) 3.5 Hz),
5.39 (1H, d, J ) 6.0 Hz), 5.32 (1H, t, J ) 5.4 Hz), 5.18 (1H, d, J
) 4.8 Hz), 4.85 (1H, d, J ) 5.7 Hz), 4.25 (2H, s), 4.10-3.90 (2H,
m), 3.78-3.52 (3H, m), 3.68 -3.55 (2H, m).
2,10-Dihydroxy-6-({[5-(hydroxymethyl)pyridin-3-yl]methyl}amino)-
13-(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-
c]carbazole-5,7(6H)-dione (56). Compound 56 was prepared in a
similar manner to the synthesis of compound 53 by substituting 38

Topoisomerase I Inhibitors, Analogues of Edotecarin
Journal of Medicinal Chemistry, 2009, Vol. 52, No. 10 3235
1
colorectal cancer: a multicentre randomised trial. Lancet 2000, 355,
1041–1047.
with compound 52a in 15% yield. H NMR (300 MHz, DMSO-
d6) δ: 11.18 (1H, brs), 9.82 (2H, brs), 8.84 (1H, d, J ) 8.5 Hz),
8.76 (1H, d, J ) 8.5 Hz), 8.55 (1H, s), 8.37 (1H, s), 7.84 (1H, s),
7.16 (1H, s), 7.00 (1H, s), 6.79 (2H, t, J ) 8.1 Hz), 6.21 (1H, t, J
) 4.7 Hz), 5.95 (1H, d, J ) 7.8 Hz), 5.93 (1H, brs), 5.40 (1H,
brs), 5.30 (1H, brs), 5.19 (1H, brs), 4.93 (1H, brs), 4.50 (2H, s),
4.56 (2H, d, J ) 4.7 Hz), 4.02 (1H, d, J ) 10.8 Hz), 4.00-3.85
(2H, m), 3.77 (1H, d, J ) 10.8 Hz), 3.54-3.40 (2H, m).
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2,10-Dihydroxy-6-({[6-(hydroxymethyl)pyridin-3-yl]methyl}amino)-
13-(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-
c]carbazole-5,7(6H)-dione (57). Compound 57 was prepared in a
similar manner to the synthesis of compound 53 by substituting 44
1
with compound 52a in 19% yield. H NMR (300 MHz, DMSO-
d6) δ: 11.12 (1H, brs), 9.82 (2H, brs), 8.81 (1H, d, J ) 8.7 Hz),
8.73 (1H, d, J ) 8.7 Hz), 8.51 (1H, s), 7.90 (1H, d, J ) 7.9 Hz),
7.39 (1H, d, J ) 7.9 Hz), 7.11 (1H, s), 6.93 (1H, s), 6.77 (2H, t, J
) 8.7 Hz), 6.21 (1H, t, J ) 3.8 Hz), 5.92 (1H, d, J ) 7.9 Hz),
5.50-4.85 (5H, m), 4.48 (2H, s), 4.27 (2H, d, J ) 3.8 Hz), 4.01
(1H, d, J ) 10.8 Hz), 3.97-3.85 (2H, m), 3.77 (1H, d, J ) 10.8
Hz), 3.54-3.40 (2H, m).
(15) Vallbohmer, D.; Iqbal, S.; Yang, D. Y.; Rhodes, K. E.; Zhang, W.;
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2,10-Dihydroxy-6-({[2-(hydroxymethyl)pyridin-4-yl]methyl}amino)-
13-(ꢀ-D-glucopyranosyl)-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-
c]carbazole-5,7(6H)-dione (58). Compound 58 was prepared in a
similar manner to the synthesis of compound 53 by substituting 50
1
with compound 52a in 20% yield. H NMR (300 MHz, DMSO-
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d6) δ: 11.17 (1H, brs), 9.82 (2H, brs), 8.85 (1H, d, J ) 8.4 Hz),
8.77 (1H, d, J ) 8.4 Hz), 8.41 (1H, d, J ) 5.1 Hz), 7.56 (1H, s),
7.47 (1H, d, J ) 5.1 Hz), 7.15 (1H, s), 6.96 (1H, s), 6.81 (2H, t, J
) 8.7 Hz), 6.26 (1H, t, J ) 4.9 Hz), 5.94 (1H, d, J ) 8.6 Hz), 5.92
(1H, brs), 5.36 (2H, brs), 5.18 (1H, brs), 4.91 (1H, brs), 4.51 (2H,
d, J ) 1.8 Hz), 4.32 (2H, d, J ) 4.9 Hz), 4.03 (1H, d, J ) 10.5
Hz), 3.97-3.86 (2H, m), 3.77 (1H, d, J ) 10.5 Hz), 3.52-3.45
(2H, m).
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Y.; Hirota, Y.; Sato, K.; Terasawa, H. Synthesis and antitumor activity
of ring A- and F-modified hexacyclic camptothecin analogues. J. Med.
Chem. 1998, 41, 2308–2318.
Acknowledgment. We are grateful to Kazuhiro Fukasawa
(in vitro assay), Tsutomu Kodera (in vivo assay), and Hirokazu
Ohsawa (HRMS measurement) for their collaboration.
(22) Saltz, L. B.; Kemeny, N. E.; Tong, W.; Harrison, J.; Berkery, R.;
Kelsen, D. P. 9-Aminocamptothecin by 72 h continuous intravenous
infusion is inactive in the treatment of patients with 5-fluorouracil-
refractory colorectal carcinoma. Cancer 1997, 80, 1727–1732.
(23) Kindler, H. L.; Avadhani, A.; Wade-Oliver, K.; Karrison, T.; Mani,
S.; Vokes, E. E. 9-Aminocamptothecin (9-AC) given as a 120 h
continuous infusion in patients with advanced adenocarcinomas of the
stomach and gastroesophageal junction: a phase II trial of the
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Supporting Information Available: Additional experimental
procedures and characterizarion for compounds 4-18, 21a-r,
28-50; HPLC and HRMS analyses data of all tested compounds;
Combustion analysis data of in vivo tested compounds 22g, 22m,
23c; Topoisomerase I-mediated DNA cleavages induced by com-
pounds. This material is available free of charge via the Internet at
http://pubs.acs.org.
(24) Bailly, C.; Lanciaux, A.; Dassonneville, L.; Demarquay, D.; Coulomb,
H.; Huchet, M.; Lavergne, O.; Bigg, D. C. H. Homocamptothecin, an
E-ring-modified camptothecin analogue, generates new topoisomerase
I-mediated DNA breaks. Biochemistry 1999, 38, 15556–15563.
(25) Lesueur-Ginot, L.; Demarquay, D.; Kiss, R.; Kasprzyk, P. G.;
Dassonneville, L.; Bailly, C.; Camara, J.; Lavergne, O.; Bigg, D. C. H.
Homocamptothecin, an E-ring-modified camptothecin with enhanced
lactone stability, retains topoisomerase I-targeted activity and antitumor
properties. Cancer Res. 1999, 59, 2939–2943.
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tothecin, 12-Cl-hCPT, showing antiproliferative and topoisomerase I
inhibitory activities superior to SN-38. Anti-Cancer Drug Des. 2001,
16, 27–36.
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Topoisomerase I Inhibitors, Analogues of Edotecarin
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JM801641T