Journal of Nuclear and Radiochemical Sciences, Vol. 8, No. 2, pp. 93-98, 2007

Studies on the Usefulness of Radioisotopes in Pharmaceutical Sciences
H. Sakurai*
Department of Analytical and Bioinorganic Chemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho,Misasagi, Yamashina-ku, Kyoto 607-8414, Japan
Received: October 23, 2006; In Final Form: October 23, 2006
The use of radioisotopes and radiation is essential in the research field of life science. This article describes thestudies on the usefulness of radioisotopes in pharmaceutical sciences, especially focusing on the results of ourresearch group as follows. (i) Mixed disulfide formation catalyzed by Cu(II) in relation to the radioprotective ability of a radioprotector, cysteamine (2-mercaptoethylamine). (ii) Suppression of reactive oxygen species (ROS) in
the skin of live animals given oral administrations of Zn(II) and its complexes in relation to the skin damage underultra-violet (UV) light. (iii) Improvement of diabetes mellitus by insulin-mimetic vanadyl(IV) (VO(II)) complexes.

1. Introduction
The use of radioisotopes and radiation is indispensable in
the research of life science, especially in pharmaceutical sciences. Research topics in pharmaceutical sciences are mainlyclassified into three research fields as follows.
(1) Trace elements in living systems and environment, where
many kinds of tracers and neutron activation analysis areused.
(2) Radioisotopes in the development of new pharmaceutics,
where a wide variety of radioisotopes are needed for radioimmunoassay, radioreceptor assay, pharmacokinetics,
imaging by autoradiography, radioprobes, drug delivery
systems, and gene technology.
(3) Radiopharmaceutics in nuclear medicine, where not onlyin vitro and in vivo diagnostic radiopharmaceutics but also
in vivo therapeutic radiopharmaceutics have extensively
been developed.
Since 1971, we have used many tracers, and performed neutron activation analysis (NAA) method (Table 1) to know thechemical action mechanism of radioprotective agents, uptakeof trace elements and glucose into the cells and organs, state ofessential trace elements in organs of animals, and metal incor-

porations in subcellular particles and organs in experimental
animals that were treated with metallo-pharmaceutics as wellas metal complexes as candidates for future metallo-pharmaceutics.
This review article describes progress in our investigation on
the research of pharmaceutical sciences, focusing on the following three topics.
(i) Mixed disulfide formation catalyzed by Cu(II) in relation
to the radioprotective ability of a radioprotector, cysteamine (2-mercaptoethylamine).
(ii) Suppression of reactive oxygen species (ROS) in the skinof live animals given oral administrations of Zn(II) and its
complexes in relation to the skin damage under ultra-violet(UV) light.
(iii) Improvement of diabetes mellitus by insulin-mimetic
vanadyl(IV) (VO(II)) complexes.
2. Mixed Disulfide Formation Catalyzed by Cu(II) in
Relation to the Radioprotective Ability of Cysteamine(2-mercaptoethylamine)
The concept of chemical protection against radiation damage in mammal was established in 1949−1955.1,2 A wide variet-

TABLE 1: Tracers and radio-nuclides used in our research group
Tracers
35

35

S-cysteamine, S-cysteine
H-glucose54Mn
2-deoxy-D-[1-3H]glucose
48
V(AVF cyclotron)
65
Zn(AVF cyclotron)
3(1971)(1990)(1990)(1999)(2003)(2005)

Multi-tracers (RIKEN ring cyclotron)
7

22

Be, Na, 47Ca, 46Sc, 48V, 51Cr, 52Mn, 59Fe, 58Co, 65Zn, 67Ga,
As, 75Se, 84Rb, 85Sr, 87Y, 88Zr, 89Zr, 99mTc, 96Tc, 97Ru, 103Ru,
and 101mRh(2001)
74

Neutron activation analyses
Mn(n, γ) Mn
846.6 keV
51
V(n, γ)52V
1434.1 keV
198
Pt(n, γ β−)199Au
158 keV76
Se(n, γ)77mSe
162 keV
197
Au(n, γ)198Au
411.8 keV
127
I(n, γ)128I
443.7 keV
65
Cu(n, γ) 66Cu
1039.2 keV
58
Fe(n, γ)59Fe
192.3 keV
64
Zn(n, γ) 65Zn
1115.5 keV
27
Al(n, γ)28Al
1778.9 keV
39
40
K(n, γ) K
1460.8 keV
133
Cs(n, γ)134Cs
795.8 keV
31
P(n, α)28Al
1778.9 keV
55

56*Corresponding author. E-mail: sakurai@mb.kyoto-phu.ac.jp. Fax:
+81-75-595-4753.

© 2007 The Japan Society of Nuclear and Radiochemical Sciences
Published on Web 10/19/2007(1985)(1987)(1988)(1988)(1988)(1990)(1992)(1992)(1992)(1996)(1997)(1997)(2004)

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SakuraiJ. Nucl. Radiochem. Sci., Vol. 8, No. 2, 2007
Cu(I)

RSH

R

R'SH

S

Cu(I)
R

S

R

S

Cu(II)Cu(II)

R

S

S

R'

S

R'

R

S

Cu(II)Cu(I)Mi xed valenc ec om pl ex

Cu(I)
S

R'

S

R'

Cu(II)

Cu(I)

R

S
Cu(I)

Mi xed val enc e-mi x ed
lig and c om p le x

Intermediate

RS

SR'

RS

SR

R'S

SR'

Mixed disultide
and symmetric
disulfides

Figure 1. Possible mechanism for mixed disulfide formation through mixed valence-mixed ligand complex catalyzed by Cu(II).
O

O

CH3

N

N

N
H
H

O

O

· O21O
2

*O

CH3

N

N-

N
H

H+
- CO2

N

O

CH3

NH

N
H

N

CH3

NH

N
H

+ hυ (380 nm)
CLA

Dioxetane

Excited state

ground state

Figure 2. CLA (2-methyl-6-phenyl-3,7-dihydroimidazo-[1,2-a]pyrazin-3-one) and its reaction with superoxide anion (·O2−) or singlet oxygen(1O2).

ies of radioprotectors involving cysteamine were proposed bymany researches. Together with the development of radioprotectors, the action mechanism for the chemical protection has
intensively been studied. The main hypotheses for the chemical protection are summarized as follows.3
1) Reactions of radioprotectors with free radical species thatare formed during the reactions of radiation and water assolvent in cells or organs and biomolecules such as proteins, lipids and nucleic acids.
2) Energy transfer of radiation through biomolecules to radioprotectors.
3) De-oxygenation effect by reductive radioprotectors.
4) Mixed disulfide formation between sulfur-containing
radioprotectors such as cysteine or cysteamine (2-mercaptoethylamine) and thiol groups of proteins or enzymes, bywhich such proteins and enzymes are protected against
radiation damage.
5) Chelate theory, which proposes the chelate formation ofradioprotectors with metal ions such as Cu and Fe that inturn catalyze the oxidative damage in cells or organs under
exposure of radiation.
Among these hypotheses, we have been interested in themixed disulfide formations consisting of different types of thiol
compounds, to which trace amount of metal ions may contribute. In order to know the contribution of complex formation ofa radioprotector, cysteamine (Cyst), which is a well-known
agent, we examined the effects of Cu(II) on the formation of
the mixed disulfide in the system of Cyst and cysteine, glutathione, or bovine serum albumin by using 35S-Cyst or 14C-cycteine at pH 7.4. Separation of the mixed disulfides wereachieved by electrophoresis, and the amounts of the mixed
disulfides were estimated by measuring the radioactivity.
Remarkable catalytic effects were observed, in which the orderof the formation yield (%) of mixed disulfides were as follows:
70% for Cyst-cysteine system, >53% for Cyst-glutathione system, and >36% for Cyst-albumin system.4
For these reactions, we speculated the mechanism following
the visible absorption spectrometry (Figure 1). When Cyst ismixed with Cu(II), a mixed valance complex, which contains

Cu(I) and Cu(II) states, is formed.5 When another type of thiol
compound is added, this compound binds to the vacant coordination sphere of central Cu(II) and a mixed valence mixed
ligand complex will be formed. This complex is altered to as
an intermediate, in which two sulfur atoms from different thiol
compounds interact each other and a new mixed disulfide will
be formed together with formations of each symmetric disulfide compound.
3. Suppression of Reactive Oxygen Species (ROS) in the
Skin of Live Animals Given Oral Administrations ofZn (II) and Its Complexes in Relation to the Skin
Damage under Ultra-violet (UV) Lights
When the skin is exposed to ultra-violet (UV) light, the reactive oxygen species (ROS) involving superoxide anion radical(·O2−), hydrogen peroxide (H2O2), hydroxyl radical (·OH), singlet oxygen (1O2), and lipidperoxides or their radicals (LOOH
or LOO·) have been proposed to form in the skin, which in turninduce skin aging, phototoxicity, inflammation, and malignant
tumors. Such proposal depended on the results obtained fromthe separated most outer layer of the skin (epidermis) or
homogenated tissues. Therefore, contradictory results were
often reported, probably due to the lack of experimental data inlive animals. Actually, there are a few reports on in vivo detection of ROS generation in the skin.6,7
In 2000, we reported the in vivo real-time detection andtwo-dimensional imaging of the generated ROS in the skin of alive animal after UVA light (320−400 nm) exposure, by meansof a chemiluminescent (CL) probe (CLA) (Figure 2) combinedwith a new ultralow-light imaging apparatus equipped with a
CCD camera (NightOWL). The method was proposed to bevery useful not only in characterizing the ROS generated in the
UV light-exposed skin but also in searching for the protective
or preventive compounds against the UV light-induced skin
injury or disorder.8,9
Because a significant difference was observed between
intrinsic and UVA-induced CL in the skin of live mice, thesorts of ROS were identified by using topical applications ofStudies on the Usefulness of Radioisotopes in Pharmaceutical Sciences

Zn(pa)2
The reason why orally administered Zn(II) or its complex
exhibits antioxidative activity in the skin under UVA exposure
is difficult to explain, where many factors contribute. We
examined the induction of metallothionein (MT), which is proposed to have an antioxidative activity in several organs involving the skin of animals, in HaCaT cells treated with ZnCl2, andfound that MT levels in the cells increased when comparedwith the non-treated cells.
In addition, to know the mechanism for the different featuresof protective ability of ZnCl2 and Zn(pa)2, we used 65Zn, which
was provided from RIKEN (Wako, Japan) in the form of65
ZnCl2. 65Zn(pa)2 was prepared from 65ZnCl2.
The time-dependent distribution of 65Zn in the skin of hairless mice treated with 65ZnCl2 or Zn(pa)2 by single oral administration at a dose of 10 mg Zn per kg of body weight wasobserved (Figure 3). Interestingly, 65Zn levels in the skin ofmice treated with 65 Zn(pa) 2 were significantly higher thanthose of mice treated with 65ZnCl 2 at 12, 24, and 72 h afteradministration, indicating that the actions of Zn on the skin are
more enhanced and prolonged by the supplementation of

95

0.3

% of dose / g of wetorgan weighttypical and specific ROS scavengers. Applications of superoxide dismutase (SOD) or β -carotene were found to greatly
reduce UVA-induced CL in the skin. Furthermore, SOD also
highly reduced intrinsic skin CL, while β -carotene hardly
reduced it. The facts that SOD is a potent 1O 2 quencher(quenching rate constant = 2.6 × 109 M−1s−1) as well as an ·O2−
scavenger (second order rate constant = 2.0 × 109 M−1s−1) and
β -carotene is a typical 1O2 quencher (quenching rate constant =3−30 × 109 M−1s−1) suggest that the intrinsic CL was due mostly
to ·O2− and that the UVA-induced CL was due predominantly
to 1O2 in the mouse skin. We thus demonstrated the direct invivo evidence for the intrinsic occurrence of ·O2− and the UVAinduced formation of 1O2 intrinsically generated in the skin oflive mice.
In searching for the protective compounds against UVA
light, we use both organic and inorganic compounds or complexes. Among many inorganic elements, Zn has been used as
an anti-inflammatory agent for many years. Then we haveused Zn of both ionic and complex forms. When ZnCl 2 was
topically applied to the live hairless mice, the CL intensity due
to ROS was significantly suppressed. Based on the finding of
this new physiological role of Zn, ZnCl2 was intraperitoneallyinjected to the hairless mice, and examined whether administered Zn(II) protects the skin again UVA light-induced damage
or not. Zn affect was observed after three days of daily ZnCl2
administration for 3 consecutive days, however, the effect disappeared after seven days. The study was further intended to
examine whether orally administered ZnCl 2 protects against
UVA-light induced skin damage in term of suppression of ROS
generation or not.
Orally administered ZnCl 2 suppressed ROS generation in
the skin of mice under UVA exposure even at three days after
the last Zn administration.
Encou raged wit h t he results, a Zn complex,bis(picolinato)Zn(II) [Zn(pa) 2], with the partition coefficientof 0.018 in n-octanol-saline system at 37 °C was orally administered in hairless mice. Zn(pa) 2 exhibited a long-term protective effect again UVA-induced ROS generation rather than theeffect of ZnCl2.10,11

J. Nucl. Radiochem. Sci., Vol. 8, No. 2, 2007

*
*

0.2

**

0.1

0
0

24

48

72

Time after administration / hFigure 3. Time-dependent distribution of 65Zn in the skin of hairlessmice after single oral administration of 65Zn-labeled ZnCl2 (open circles) or Zn(pa) 2 (closed circles). Significance levels: * p < 0.05 and** p < 0.01 of Zn(pa) 2 group vs. ZnCl2 group at the same samplingtime.

Zn(pa)2 than those of ZnCl2.
4. Improvement of Diabetes Mellitus by Insulin-mimetic
Vanadyl(IV) (VO(II)) Complexes
Among several lifestyle-related diseases involving hypertension, hyperlipemia, obesity, diabetes mellitus, myocardial
infarction, and cerebral embolism, the diabetes mellitus (DM)is one of the most important diseases, since the patients suffering from DM in the 21st century increase more than in the 20th
century and they develop many secondary complications suchas atherosclerosis, microangiopathy, renal disfunction and failure, cardiac abnormality, diabetic retinopathy, and ocular disorders. In general, DM is classified into type 1 DM caused bydestruction of pancreatic B cells, and type 2 DM caused byaging, obesity, spiritual stress or other environmental factors,
that are treated by daily injections of insulin and several typesof synthetic therapeutic compounds, respectively, for survival.
Unfortunately, the injections of insulin several times in a day
are painful and give the patient stress, especially in baby andyoung people less than 25 years old, and synthetic compounds
often exhibit some severe side effects containing hypoglycemia, anemia, hepatic disorder, and agranulocytosis. To overcome these defects, the creation of new classes of thetherapeutic compounds based on new concepts is urgently
anticipated.
As one of the new concepts, we examined the possibility touse metal ions and their complexes on oral administrations inplace of insulin injection, in the first stage of our study, andfound the usefulness of biometals such vanadyl (VO(II)) andzinc (Zn(II)) as insulin-mimetic metal ions, in which the inhibition of the release of free fatty acids (FFA) from the isolated
rat adipocytes (adipose cells prepared from the eqididymal fat
tissue) by metal ions was evaluated.
In fact, when streptozocin-induced type 1-like DM rats
(STZ-rats) were given daily ip injections of VOSO 4 , theirserum glucose levels dropped from hyperglycemic to normal
levels within 2 days and serum free fatty acids (FFA) levels
also dropped to normal. However, the plasma insulin levels
remained low, suggesting that the VO(II) action is peripheral.
Total V was found to be incorporated into most organs as wellas adipose tissues, as determined by neutron activation analysis(NAA). V was incorporated into the organs in the following
order (µg V g−1 wet weight): kidney > liver > bone > pancreas;

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SakuraiJ. Nucl. Radiochem. Sci., Vol. 8, No. 2, 2007

N2S2 coordination mode

H3COOC

O

S

CH2

CH2

NH2

V

S

NH2

S4 coordination mode

COOCH3CH2

CH2 CH2CH2

CH2 CH2

S

N C

S

O

S

V

N

C

S

O2S2 coordination mode

CH2

CH2

S

CH2

CH2

N O

V

O N
S

VO(opt)2

VO(pdc) 2VO(cysm)2O

N2O2 coordination mode
O

O
N

O

O

N

V

O

O
N

O

CH3

O
V

H3C

O

N
O

N

O

I

VO(6mpa)2VO(p a) 2

O

I

O
V

N
O

O

VO(5ipa)2

O4 coordination mode
O
O

C
C

O
O

O
V

O
O

VO (ox ) 2

C
C

O

O
H2C

O

O

O
O

O
V

O
O

O

O

CH2
O
O

VO(ma)2

O

O

O
V
O
O
O
O
V
O
O
O

O

O
O

N

O

N

O

O

(VO) 2(tar)2

N4 coordination mode

O

V

SO3H

HO3S

N O N
V
N

V O ( o p d )2

SO3H

N

SO3H

VO(tpps)

Figure 4. Insulin-mimetic vanadyl (VO(II)) complexes with different coordination modes.

it was also incorporated into the supernatant of the kidney andmitochondria of the liver. V was thus assumed to act in part on
the islet of the pancreas, on mineralization of bone, on electrontransport systems or induction of metallothionein (MT) in thekidney, and on the liver.12
It is interesting to note that no significant differences in V
uptake of normal and STZ-rats was observed. Both VO(II)and total V in several organs of STZ-rats treated with VOSO 4
could be determined by electron spin resonance (ESR) spectrometry at 77 K. In almost all organs, approximately 90% of
the V was found to be present in the VO(II) form.
Possible ligands to the VO(II) in organs were also estimatedby ESR spectrometry for freshly isolated organs such as liver,kidney, and serum of STZ-rats treated with VOSO4, in which acharacteristic eight-line signal due to VO(II) was observed. To
know the coordination mode around the detected VO(II) species, ESR parameters (A -value as a hyperfine coupling constant and g -factor as a universal constant, characteristic of theparamagnetic species) were compared with those of several
model VO(II) complexes with various coordination modes
around the VO(II). The relationship between two ESR parameters (A  vs. g ) for VO(II) complexes suggested that the
VO(II) species in tissues was predominantly in an oxovanadium (VO(II)) form with a square pyramidal structure, inwhich VO(II) was coordinated with four oxygen ligands ofeither water or oxyamino acid residues in proteins.12
Because uptake of V in animals given oral VOSO4 is very
low, we tested some VO(II) complexes to enhance the bioavailability of VOSO4 in STZ-rats.
I n 1990, we f i rst found t hat bis (met hylcysteinato)[VO (cysm) 2 ] -, bis (oxalato) [VO (ox) 2 ] -, bis (malonato)[ VO (m a l) 2 ] -, a nd bi s (s a l icyl a ld e hydo) [ VO (s a l) 2 ] oxovanadium(IV) as well as bis((+)-tartarato) [(VO) 2 (tar) 2 ]dioxovanadium(IV) complexes with either the VO(N2 S2 ) orVO(O4) coordination mode show the normoglycemic effects in
STZ-rats when orally administered daily, the order being
VO(mal) 2 > VO(cysm) 2 > (VO) 2 (tar) 2 > VO(sal) 2 > VO(ox) 2
with the action of dose-dependency in the V concentration
range of 1−10 mg kg−1 body weight of rats.13 This finding indicated that the chelation of VO(II) enhances the bioavailabilityof VO(II) and the change of ligand around the VO(II) alters
highly the insulin-mimetic action.
In addition, ESEEM (electron spin echo envelope modulation) spectrometry was applied to reveal a more detailed invivo coordination structure of the VO(II) state in the organs ofrats treated with VOSO 4. The ESEEM spectra of the kidney
and liver measured at 77 K demonstrated the occurrence ofnitrogen(N)-coordination to a certain percentage of VO(II),when they were compared with several model VO(II) complexes and proteins. The ratios of N coordinating VO(II) were
estimated as 70−80% in the liver, and 50−55% in the kidney.
Isotopic portions of the 14N hyperfine coupling were estimated
as |Aiso| = ~5.0 MHz for the liver, and ~5.2 MHz for the kidney,
indicating that the coordinating N was an amino nitrogen.
Thus, in vivo coordination of Lys ε -amino or N-terminal α amine of a protein (or a peptide) to VO(II) was suggested.14
In finding of insulin-mimetic VO(II) complexes in vitro, weevaluate both the enhancing effect of glucose uptake and theinhibitory effect of free fatty acids (FFA) release in the isolated
rat adipocytes treated with epinephrine (adrenaline). FFA andglucose levels in the outer solution of the cells were determined. In view of the importance of finding more active
VO(II) complexes, we prepared a large number of complexes
with different coordination modes and found the therapeuticcandidates as shown in Figure 4.15−18
Among them, bis(picolinato)oxovanadium(IV)[VO(pa) 2 ]complex with the VO(N2O2) coordination mode is particularlyinteresting in having advantage for examining the structure-

Studies on the Usefulness of Radioisotopes in Pharmaceutical Sciences

activity relationship by adding suitable substituents on the picolinate as a leading ligand.19
On the basis of the results, it was concluded that in vitro
insulin-mimetic activity, real-time metallokinetic character andin vivo antidiabetic action of VO(pa) 2 complexes are closely
related to their chemical structures; the position of a substituent
changes the sensitivity of the complex in animals.20 The longterm activity of orally administered VO(6mpa) 2 in STZ-rats
was observed, which might be related to the accumulation of V
in organs of animals.
Organ distribution of total V in STZ-rats receiving daily ip
treatments of VO(6mpa)2 (59 µmol V kg−1 body weight for the
first day and 39 for 2 days, and then 20 for 11 days, and then notreatment for 7 days) was then examined by NAA method. The
order of V concentration (µg g−1 wet weight) was as follows:bone > kidney > spleen > liver > adipose > pancreas > lung >heart > brain, suggesting that accumulation of V in the boneaccounts the long-term acting of VO(6mpa) 2.19 In addition, theformation of ternary complexes consisting of 6-methylpicolinate-VO(II)-protein or amino acids was revealed by ESEEM,
indicating also the long-term acting of VO(6mpa)2.21
To find another types of insulin-mimetic complexes, we
focused on bis(3-hydroxy-4-pyronato)oxovanadium(IV)compl
ex with VO(O4) coordination mode, since this complex has also
an advantage to examine the structure-activity relationship.
During the study, we found an excellent VO(II) complex withallixin, which was isolated from dried garlic (Allium SativumL.) as a new non-sulfur phytoalexin.

J. Nucl. Radiochem. Sci., Vol. 8, No. 2, 200797

VO(alx) 2 (Table 2). Interestingly, VO(alx) 2 showed a higher
distribution of V in the muscle than VO(ma) 2 . These results
suggested that VO(alx) 2 has a potent hypoglycemic effect due
to the higher distribution of V to the muscle, which is an important target tissue for insulin, than that of VO(ma)2.22
Based on the results, we further examined whether or notVO(alx) 2 treats type 2 DM with low insulin sensitivity. Oral
treatment of obsesity-linked type 2 diabetic KK-Ay mice withVO(alx)2 for 4 weeks normalized hyperglycemia, glucose intolerance, hyperinsulinemia, hyperleptinemia, hypercholesterolem ia, and hyper tension, however, it has no effect on
hypoadiponectinemia. From these results, VO(alx) 2 was proposed to enhance not only insulin sensitivity but also leptin
sensitivity, which in turn improve diabetes, obsesity, and hypertention in the animals.23
V concentration in the tissues of KK-Ay mice treated withVO(alx) 2 was determined by NAA method (Table 2). V wasdetectable in almost all organs; the order of distribution was asfollows: bone > kidney in liver > spleen > adipose > pancreas >muscle.23 Previously, we hypothesized that V accumulated in
the bones may be due to the long-term acting characteristic of
V compounds. Although V compounds were suggested to be
toxic to the bone marrow and cause anaemia, no impairment
was observed in the hepatic and renal systems of VO(alx) 2 treated KK-Ay mice. From these results, VO(alx) 2 was proposed to treat not only type 1 diabetic animals but also
obesity-linked type 2 diabetes.
Acknowledgments. I am grateful to Mr. Y. Adachi, Mr. T.
Takino, Mrs. A. Tamura, Mr. H. Nishimura, Dr. J. Fugono, Dr.
Y. Yoshikawa, Dr. H. Yasui (Kyoto Pharmaceutical University),Prof. A. Katoh (Seikei University), Dr. Y. Kodera (Wakunaga
Pharmaceutical Company), Dr. J. Takeda, late Prof. M. Koyama(Kyoto University), Prof. S. Hirai (Musashi Institute ofTechnology), Dr. S. Enomoto, and Dr. H. Haba (RIKEN) for
their great contribution to the research. The last part of thestudy was supported in part by grants from the Ministry of
Education, Culture, Sports, Science and Technology (MEXT)
of the Japanese Government (Grants-in-Aids for Scientific
Research (B), Scientific Research of Priority Area, andSpecially Promoted Research).

VO(alx)2
Bis(allixinato)oxovanadium(IV) [VO(alx) 2 ] exhibited not
only a high in vitro insulin-mimetic activity in terms of FFA
release inhibitory and glucose-uptake enhancing activities inisolated rat adipocytes but also a high hypoglycemic effect in
STZ-mice by both ip injections and oral administrations.22
V, which was determined by NAA method, was detectablein almost all tissues of STZ-mice given VO(alx) 2, particularly,
bone, spleen, liver, pancreas, and skeletal muscle, in this order,
similarly to those given bis(maltolato) oxovanadium(IV)[VO(ma) 2 ], which has the same coordination structure toReferences(1) H. M. Patt, E. B. Tyree, H. L. Straube, and D. E. Smith,
Science 110, 213 (1949).
(2) D. G. Doherty and W. T. Burnett, Jr., Proc. Soc. Exptl.
Biol. Med. 89, 312 (1955).
(3) Z. M. Bacq, Chemical Protection against Ionization
Radiation, Charles C Thomas Publish, New York (1965).
(4) H. Sakurai, A. Yokoyama, and H. Tanaka, Chem. Pharm.
Bull. 19, 1416 (1971).

TABLE 2: Organ distribution of vanadium in mice treated with VO(alx) 2 and VO(ma) 2
AnimalMice (ddY)
STZ-mice

KK-Ay mice
KK-Ay mice

Administeredcomplex

Plasma

Bone
n.d.
4.6
4.0

Vanadium content / µg g–1 of wet tissue)
Liver
KidneySpleen Pancreas
n.d.
n.d.
n.d.
n.d.
1.1
0.76
1.2
0.91
1.0
0.87
1.1
0.56

n.d.

n.d.

n.d.

n.d.

n.d.

1.7

31

5.3

5.2

4.0

VO(ma)2 *VO(alx)2 *VO(alx)2**

Muscle
n.d.
0.10
0.16

Adipose

n.d.

n.d.

n.d.

1.1

0.8

1.1

* Administration doses of ip injections: 5 mg (98 µmol) V /kg/day at the first day and then it was decreased to 0.1 mg (2 µmol) V/kg/day for 13 days.
** Administration doses of oral administrations: 3–7 mg (59–137 µmol) V /kg/day for 4 weeks.

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J. Nucl. Radiochem. Sci., Vol. 8, No. 2, 2007

(5) H. Sakurai, A. Yokoyama, and H. Tanaka, Chem. Pharm.
Bull. 18, 2373 (1970).
(6) P. Evelson, C. P. Ordonez, S. Llesuy, and A. J. Boveris,
Photochem. Photobiol. B38, 215 (1997).
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57 (2002).
(8) H. Yasui and H. Sakurai, Biochem. Biophys. Res.
Commun. 269, 131 (2000).
(9) H. Sakurai, H. Yasui, Y. Yamada, H. Nishimura, and M.
Shigemoto, Photochem. Photobiol. Sci. 4, 715 (2005).
(10) H. Sakurai, H. Yasui, K. Mishina, and H. Nishimura,
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