Synthesis of antitumor dendritic imides

Article abstract of DOI:10.1016/S0960-894X(01)00618-7

Dendritic imides were synthesized and evaluated as antitumor compounds. Compounds 8 and 11 showing a promising profile as inhibitors of lck but their antiproliferative activity against HT-29 was not so relevant.

Full text of DOI:10.1016/S0960-894X(01)00618-7

Bioorganic & Medicinal Chemistry Letters 11 (2001) 3027–3029
Synthesis of Antitumor Dendritic Imides
Miguel F. Brana,a,* Gema Domınguez,a Beatriz Saez,a Cynthia Romerdahl,b
Simmon Robinsonb and Teresa Barlozzarib
aDepartment of Organic and Pharmaceutical Chemistry, University San Pablo-CEU, Boadilla del Monte 28668, Madrid, Spain
bBASF Bioresearch Corporation, 100 Research Drive, 01605 Worcester, MA, USA
Received 20 February 2001; revised 4 July 2001; accepted 7 September 2001
Abstract—Dendritic imides were synthesized and evaluated as antitumor compounds. Compounds 8 and 11 showing a promising
profile as inhibitors of lck but their antiproliferative activity against HT-29 was not so relevant. # 2001 Elsevier Science Ltd. All
rights reserved.
Introduction
Chemistry
DNA intercalating agents are among the most common
anticancer drugs used in the clinical therapy of human
tumors. In our laboratory, we have discovered the anti-
tumor potential of a series of mono and bisintercalating
agents bearing naphthalimide chromophores.1 Two
compounds from this class (Fig. 1) amonafide and
elinafide have been selected for phase II clinical trials.2
On the other hand, although dendrimers with chains of
amine ramification have been employed in gene ther-
apy,3 their chemical modification to join intercalating
chromophores as antitumor compounds has never been
described. Thus, the synthesis and pharmacological
profile of such compounds could be of great interest.
Our goal was to improve the therapeutic properties of
these imides by means of increasing the binding affinity
towards the DNA molecule when branching the basic
chain to generating dendrite-like structures4 (Fig. 2).
Thus, the increase of potential hydrogen bonds and
favorable electrostatic interactions between the proto-
nated amino groups of the dendritic chains and the
negatively charged sugar phosphate backbone should
largely increase the affinity for DNA of these polymeric
structures and the potency of the intercalator.5 Although it
is well known that the addition of polyamines to a solution
of DNA–ethidium bromide complex displaces the inter-
calating agent from the double helix, it has been predicted
that a multitude of anionic site charges are available for
binding of additional basic functions beyond those present
in the intercalator framework,6 in a similar way like it
has been proposed in our work.
We have synthesized a series of imide derivatives linked
to a branched basic chain. To carry out the synthesis,
we first built the dendritic chain by a divergent proce-
dure, as described by Vogtle7 and Worner,8 starting
from a bi-directional core. The chosen core was N-tert-
butoxycarbonyl derivative, 1. A repetition of a double
Figure 1.
*Corresponding author. Tel.: +34-91-372-4771; fax: +34-91-372-
4009; e-mail: mfbrana@ceu.es
Figure 2.
0960-894X/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved.
PII: S0960-894X(01)00618-7

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M. F. Bran˜a et al. / Bioorg. Med. Chem. Lett. 11 (2001) 3027–3029
Scheme 1. (a) Acrylonitrile, MeOH; (b) H2, Ni-Raney, 1.4 M NaOH in 95% EtOH; (c) TFA, CH2Cl2/anysol 1:1, 20 min, 80%.
Scheme 2. (a) Aromatic anhydride, absolute EtOH, rt; 4: 18 h, 92%; 5: 18 h, 53%; 6: 48 h, 60%; 7: 2 h, 80%; (b) H2, Ni-Raney, 1.4 M NaOH in 95%
EtOH; 8: 48 h, 52%; 9: 24 h, 60%; 10: 24 h, 49%; 11: 16 h, 77%.
Michael addition of acrylonitrile to primary amines9
followed by hydrogenation with Ni-Raney at room
temperature and at 60 psi in a solution of 1.4 M NaOH
provided finally the octacyano 2, with a good overall
yield. Cleavage of the tert-butoxycarbonyl group with
trifluoroacetic acid provided compound 3, with the free
amine moiety (Scheme 1). Imide derivatives were pre-
pared by nucleophilic addition of the dendritic amine 3
to the appropriate 1,8-naphthalic anhydride-3-sub-
stituted to provide compounds 4–6.10 Also, we synthe-
sized the imide derivative of 3,4-diphenyl maleic
anhydride 7, because this system exhibits relevant cyto-
static activity.11 Finally, reduction of end cyano groups
of compounds 4–7 in described same conditions, led us
to the target molecules 8–1112 (Scheme 2).
available at the laboratory.14 The activity profile against
HT-29 cell lines was not relevant probably due to poor
permeabilities. However, compounds 8 and 11 showed
high activity as inhibitors of lck. It appears that lck
expression is largely confined to Tcells, and its over
expression may contribute to certain T-cell tumors.15
Thus, selective inhibition of the lck function may be of
Table 1. Biological activities against HT-29 and lck
Compd
HT-29
ID50 (mM)
Lck
IC50 (mM)
3
4
5
6
7
8
9
10
>100
>100
>100
>100
57
3.8
>50
33.8
5.02
>50
0.39
44
a
a
—
—
—
Biological Evaluation
a
a
—
0.10
11
Amonafide
Elinafide
100
38
0.014
In vitro cytotoxicity against human colon carcinoma
cell line HT-29 was carried out.13 Also, we tested some
of these compounds against lck because this receptor
has a great interest and this biological system was
a
—
—
a
aNot determined.

M. F. Bran˜a et al. / Bioorg. Med. Chem. Lett. 11 (2001) 3027–3029
3029
interest for the treatment of several types of lymphomas
such as non-Hodgkin16 which express lck function. These
results open up a new area of future research (Table 1). In
conclusion, in this work we have synthesized new imide
derivatives linked to a dendritic chain. Biological assays
show no relevance for the activity of these compounds
against HT-29 cell lines and values range around
10ꢀ5 mM. However, results obtained for the inhibition of
lck seem promising and an excellent starting point for
further development of this type of approximation in
the search for new antitumor compounds.
10. Typical procedure for synthesis of imide derivatives: To a
solution of 3 (0.89 g, 1.08 mmol) in 50 mL of absolute ethanol
was added 0.21 g, (1.08 mmol) of 1,8-naphthalic anhydride and
the mixture was stirred for 18 h at room temperature. The
solvent was removed under reduced pressure to obtain 0.89 g
(92%) of 4 as a light brown oil. 1H NMR (CDCl3): d 1.64 (m,
12H, 6CH2, CH2CH2CH2), 2.50 (t, 24H, 12CH2, CH2CH2N,
J=6.6 Hz), 2.59 (t, 16H, 8CH2, NCH2CH2CN, J=7.1 Hz),
2.75 (t, 2H, CH2, NCH2CH2NCO, J=7.1 Hz), 2.86 (t, 16H,
8CH2, CH2CN, J=87.1 Hz), 4.26 (t, 2H, NCH2CH2NCO,
J=7.1 Hz), 7.78 (t, 2H, Har, J=7.7 Hz), 8.24 (d, 2H, Har,
J=8.2 Hz), 8.5 (d, 2H, Har, J=7.1 Hz). 13C NMR (CDCl3): d
163.8, 133.8, 131.3, 130.8, 127.7, 126.7, 122.1, 118.7, 52.3, 51.5,
51.2, 50.9, 49.1, 44.1, 37.6, 24.3, 23.9, 16.5. IR (neat): 2240,
1700, 1610 cmꢀ1
.
Acknowledgements
11. Brana, M. F.; Fernandez, A.; Garrido, M.; Rodriguez,
M. L.; Morcillo, M. J.; Sanz, A. M. Chem. Pharm. Bull. 1989,
37, 2710.
We are grateful to DGICYT(MEC-Spain, Grant
SAF96-0045) and Knoll-BASF for financial support. B.
Saez acknowledges Universidad San Pablo-CEU for a
predoctoral fellowship.
12. Typical procedure for synthesis of primary amines via
reduction: To 25 mL of a 1.4 M solution NaOH in 95% etha-
nol, 1.13 g (1.12 mmol) of 4, were added. The mixture was
treated with 1.8 g of Ni-Raney and it was hydrogenated at 60
psi for 48 h at room temperature. The catalyst was filtered
through Celite and washed with 95% ethanol. After diluting
the filtrate with H2O, ethanol was evaporated and the residue
extracted several times with CH2Cl2. Thereby, the NaOH
concentration in the aqueous phase was increased in every
extraction step. The organic layers were dried with Na2SO4
and the solvent evaporated under vacuo to give 0.58 g (50%)
of 8 as a light brown oil. 1H NMR (D2O): d 1.40–1.56 (m,
28H, 14CH2, CH2CH2CH2), 2.32–2.43 (m, 42H, 21CH2,
CH2N), 2.70 (m, 16H, 8CH2, CH2NH2), 3.97 (bs, 2H, CH2,
CH2NCO), 7.59 (bs, 2H, Har), 8.19 (bs, 4H, Har). 13C NMR
(D2O): d 163.3, 128.9, 127.6, 127.5, 127.4, 57.1, 50.3, 50.1,
48.0, 38.3, 27.6, 27.0, 24.8, 20.9. IR (neat): 3500, 1700,
References and Notes
1. Romerdahl, C. A.; Brana, M. F. In Cancer Therapeutics
and Clinical Agents; Teicher, B. Ed; Humana: Totowa, NJ,
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4. This work was presented at the 90th Annual Meeting of
American Association of Cancer Research, Philadelphia, PA,
April 10–14, 1999. Domınguez, G., Brana, M. F., de Pascual-
Teresa, Saez, B. Proceedings of 90th Annual Meeting of AACR,
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1610 cmꢀ1
.
13. The cytotoxicity of these compounds against HT-29 was
measured using a standard MTT assay.17 Human colon carci-
noma cell line HT-29 was obtained from American Type Cul-
ture Collection.
14. Human recombinant lck catalytic domain was produced
in a baculovirus expression system. Purified protein was used
and IC50 values were determined by an enzyme linked
immunosorbent (ELISA) phosphorylation assay using the
universal tyrosine kinase substrate Poly(Glu,Tyr) 4:1 at 5 mM
ATP.18
5. This approach was further supported by molecular model-
ing studies in which has been determinated that these com-
pounds are likely to bind a DNA octamer of a model
d[GCACGTCG]2 sequence through the central 50-CpG-30 step
via either the mayor or the minor groove.4
6. Atwell, G. J.; Cain, B. F.; Denny, W. A. J. Med. Chem.
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88, 3977.
9. Typical procedure for synthesis of oligonitriles via cya-
noethylation: To a cold solution of the polyamine (1.0 g,
1.9 mmol) in methanol (18 mL) were added dropwise 19 mL
(288 mmol) of acrylonitrile. After stirring 1 h at 10 ꢁC and 4
days at 60 ꢁC, the quantitative biscyanoethylation was
obtained. The solvent was evaporated under vacuo to obtain
an oil which was purified by low pressure distillation.
16. Marth, J. D.; Disteche, C.; Pravtcheva, D.; Ruddle, F.;
Krebs, E. G.; Perlmutter, R. M. Proc. Natl. Acad. Sci. U.S.A.
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B. B. Anal. Biochem. 1992, 203, 151.