A novel d-glucose derivative radiolabeled with technetium-99m: Synthesis, biodistribution studies and scintigraphic images in an experimental model of Ehrlich tumor

Article abstract of DOI:10.1016/j.bmcl.2010.03.003

A d-glucose-MAG₃ derivative was successfully synthesized and radiolabeled in high labeling yield. Biodistribution studies and scintigraphic images in Ehrlich tumor-bearing mice were performed. This compound showed high accumulation in tumor tis

Full text of DOI:10.1016/j.bmcl.2010.03.003

Bioorganic & Medicinal Chemistry Letters 20 (2010) 2478–2480
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Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
A novel D-glucose derivative radiolabeled with technetium-99m: Synthesis,
biodistribution studies and scintigraphic images in an experimental model
of Ehrlich tumor
André Luís Branco de Barros, Valbert Nascimento Cardoso, Luciene das Graças Mota, Elaine Amaral Leite,
*
Mônica Cristina de Oliveira, Ricardo José Alves
Faculdade de Farmácia, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31279-901, Belo Horizonte, Minas Gerais, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
A
D
-glucose-MAG3 derivative was successfully synthesized and radiolabeled in high labeling yield.
Received 27 January 2010
Revised 26 February 2010
Accepted 1 March 2010
Available online 3 March 2010
Biodistribution studies and scintigraphic images in Ehrlich tumor-bearing mice were performed. This
compound showed high accumulation in tumor tissue with high tumor-to-muscle ratio. Thus,
cose-MAG3 could be considered as agent for tumor diagnosis.
D-glu-
Ó 2010 Elsevier Ltd. All rights reserved.
Keywords:
D-glucose
Technetium-99m
MAG3
Tumor
Diagnosis agents
Cancer is one of the most common causes of death. Tradition-
ally, the diagnosis was based on anatomical details of the organs
under study. But, with the advent of nuclear medicine, it has be-
come possible to identify biochemical changes in the disease even
before the presence of anatomical changes can be observed. ‘In
vivo’ functional imaging may aid in the diagnosis and therapy of
patients so as to increase their survival rate.1,2
properties such as a physical half-life of 6.01 h and low energy
gamma emission (140 keV), in addition to a relatively low cost
when compared with [18F] fluoride.1,11–14
An experimental model that can be used to search for tumor is
based on the implantation of Ehrlich tumor cells in the hind thigh
of mice. The tumor is of the rapidly developing Ehrlich cells from
easily transplantable mammary adenocarcinoma from female
mice. Such cells have been employed as a model in the study of
various products used to treatment and diagnoses.15,16
Positron emission tomography (PET) with the [18F] 2-fluoro-2-
deoxy-
D
-glucose, ([18F] FDG) is widely used in the diagnosis and
monitoring of cancer.3 The [18F] FDG is an analogue of
D-glucose,
Carbohydrates such as D-glucose are generally weak ligands for
and its uptake is based on the higher glycolytic enzyme activity
complexation with 99mTc. Thus, the functionalization of the sugar
with an external chelating group is crucial for obtaining a com-
pound that effectively binds the metal.17
of malignant cells compared to normal tissue.2,4–6
Although the metabolic imaging of tumors with [18F] FDG has
been studied for over two decades, its clinical use is still limited be-
cause of some factors such as difficult access, limited availability
and high cost. The development of diagnostic agents based on
gamma radiation-emitting isotopes for the production of images
in conventional scintillation cameras would be of great value.1,7
Some studies have been conducted in an attempt to develop
The mercaptoacetylglycylglycylglycine is a complexing agent of
proven effectiveness for 99mTc, and it is used as a renal tubular
radiotracer.18,19 It has a carboxylic acid group that can couple with
compounds containing amino groups.
The purpose of this study was performed the biodistribution
studies and scintigraphic images of 99mTc-MAG3 and the new com-
plex 99mTc-MAG3-glucose for evaluating the feasibility of the
99mTc-labeled glucose derivative as candidate for tumor diagnosis
agent.
new radiopharmaceuticals involving technetium-99m
(
99mTc)
complexes with analogues of D-glucose for the diagnosis of can-
cer.1,4,8–10 The 99mTc is the most widely used radionuclide in nucle-
ar medicine because it presents appropriate physical and chemical
The
the procedure outlined in Scheme 1.
The 4-nitrophenyl b- -glucopyranoside 1 was reduced to 4-
aminophenyl b- -glucopyranosíde 2 using catalytic hydrogenation.
D-glucose-MAG3 derivative 6 was synthesized according to
D
* Corresponding author. Tel./fax: +55 31 3409 6955.
E-mail address: ricardodylan@farmacia.ufmg.br (R.J. Alves).
D
0960-894X/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2010.03.003

A. L. B. de Barros et al. / Bioorg. Med. Chem. Lett. 20 (2010) 2478–2480
2479
O
H
HO
N
N
H
NH2
O
O
3
b
OH
O
O
H
N
O
HO
HO
O
HO
Cl
N
H
N
H
OH
1
O
O
NO2
4
a
c
OH
O
H
N
O
O
HO
HO
O
S
HO
N
H
N
H
OH
+
O
O
O
NH2
2
5
d
OH
O
HO
HO
O
O
H
O
H
O
OH
N
N
N
H
N
S
O
H
O
6
Scheme 1. Synthesis of Bz-MAG3-G (6). Reagents and conditions: (a) H2, Pd/C, methanol, yield: 100%; (b) chloroacetyl chloride, diethylether and water; (c) thiobenzoic acid,
methanol, yield: 78%; two steps; (d) EDAC, dry DMF, yield: 32%.
Table 1
The intermediate 2 was then reacted with benzoylated MAG3 5,
Biodistribution of 99mTc-MAG3 in Ehrlich tumor-bearing mice (%ID/g)a
previously synthesized from 3, using N-(3-dimethylaminopro-
pyl)-N0-ethylcarbodiimide (EDAC) as coupling agent to obtain 6.
Tissue
5 min
30 min
120 min
240 min
All compounds were characterized by 1H NMR and 13C NMR
Liver
7.62 1.02
20.43 2.15
1.69 0.39
7.53 0.45
19.74 5.06
1.80 0.42
1.47 0.22
2.24 0.19
4.99 1.35
2.08 0.25
1.05 0.14
91.69 5.64
0.68 0.11
0.55 0.05
1.58 0.30
2.64 0.64
0.68 0.12
0.71 0.17
51.96 9.29
0.39 0.09
0.34 0.06
1.39 0.15
2.16 0.44
1.43 0.33
0.74 0.17
73.52 6.55
0.38 0.07
0.35 0.07
spectroscopy.20 The technetium-99m labeled
D-glucose-MAG3
Kidneys
Stomach
Blood
Bladder
Tumor
Muscle
(
99mTc-MAG3-G) and the 99mTc-MAG3 were prepared by ligand-ex-
change reaction with 99mTc-tartarate at pH 6–8. In this condition
the benzoyl protecting groups of 5 and 6 are removed.18
After radiolabeling the products were purified by column
chromatography on Florisil mesh 60–100, using, first, acetone to
a
Injected dose 0.1 ml/370KBq. Data are expressed as percentage of %ID/g of
remove TcO4 and next, 0.9% saline to elute the 99mTc-MAG3-G.
ꢀ
tissue S.D. (n = 5).
The radiolabeling yields were determined by Instant Thin Layer
Chromatograph (ITLC) on two systems: 0.9% saline to determine
TcO2 and acetone to determine TcO4ꢀ, as published elsewhere.21
The radiochemical purities were higher than 90%.
Table 2
Biodistribution of 99mTc-MAG3-G in Ehrlich tumor-bearing mice (%ID/g)a
Biodistribution of these complexes were performed in Ehrlich
tumor-bearing Swiss mice (25–30 g) at 5, 30, 120 and 240 min post
injection. The results are summarized in Tables 1 and 2. Both com-
plexes were excreted rapidly through kidneys. The 99mTc-MAG3-G
had higher tumor-to-muscle (T/M) ratio than 99mTc-MAG3 at all the
times investigated (Table 3). It has been considered in the litera-
ture22 that radiotracers that have a target/non-target ratio greater
than 1.5 (50% greater capture in the target tissue) may be consid-
ered to be potential diagnostic agents. In a recent paper1 a target/
non-target ratio of about 3.0 was described for a derivative similar
Tissue
5 min
30 min
120 min
240 min
Liver
7.03 1.07
14.62 4.50
3.46 0.47
6.09 0.70
44.25 8.87
2.25 0.22
1.11 0.13
3.69 0.86
3.72 0.61
5.71 0.20
1.89 0.37
93.95 12.97
1.37 0.11
0.63 0.10
2.05 0.46
2.15 0.40
4.24 0.57
0.72 0.10
37.14 8.10
0.50 0.04
0.24 0.03
2.23 0.52
2.54 0.33
2.69 0.51
0.49 0.07
55.83 11.85
0.45 0.04
0.21 0.03
Kidneys
Stomach
Blood
Bladder
Tumor
Muscle
a
Injected dose 0.1 ml/370KBq. Data are expressed as percentage of %ID/g of
tissue S.D. (n = 5).

2480
A. L. B. de Barros et al. / Bioorg. Med. Chem. Lett. 20 (2010) 2478–2480
Table 3
Table 4
Target/non-target ratio for 99mTc-MAG3 and 99mTc-MAG3-GA
Target/non-target ratio for 99mTc-MAG3 and 99mTc-MAG3-G obtained by gamma
camera images (%ID/cm2)A
Radiotracer
5 min
30 min
120 min
240 min
Radiotracer
5 min
30 min
120 min
240 min
99mTc-MAG3
1.22a 0.14
2.05b 0.25
1.22a 0.10
2.22b 0.24
1.16a 0.08
2.13b 0.12
1.10a 0.11
2.10b .24
99mTc-MAG3-G
99mTc-MAG3
1.23a 0.02
1.80b 0.10
1.09a 0.07
2.02b 0.09
1.18a 0.12
1.95b 0.12
1.13a 0.13
1.93b 0.06
99mTc-MAG3-G
A
The results are expressed as the mean S.D. (n = 5). The values were evaluated
by the Tukey-Kramer test. Different letters indicate statistically significant
differences.
A
The results are expressed as the mean S.D. (n = 3). The values were evaluated
by the Tukey-Kramer test. Different letters indicate statistically significant
differences.
group. After purification by column chromatography, a radiochemi-
cal purity superior to 90% was observed. The biodistribution studies
and the scintigraphic images in animals showed that 99mTc-MAG3-G
had a higher affinity for the tumor than the 99mTc-MAG3 complex.
These data suggest that the 99mTc-MAG3-G complex could be used
as a possible agent for identification of tumors. Further studies will
be carried out to evaluate the real potential of 6 for tumor diagnosis
and will be reported in due course.
Acknowledgments
We thank CNPq, CAPES and FAPEMIG for grant and fellowships.
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Figure 1. Scintigraphic images with Ehrlich tumor-bearing mice 240 min after
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with technetium-99m after removal of the benzoyl protecting