Biosci. Biotechnol. Biochem., 74 (7), 1476–1478, 2010
Note
Acute and Sub-Chronic Toxicity of D-Allose in Rats
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1;
Yusuke IGA,1 Kazunori NAKAMICHI,1 Yoko SHIRAI,2 and Tatsuhiro MATSUO
1Faculty of Agriculture, Kagawa University, Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0795, Japan
2National Institute for Materials Science, Namiki, Tsukuba, Ibaraki 305-0044, Japan
Received February 22, 2010; Accepted April 21, 2010; Online Publication, July 7, 2010
We examined the acute and sub-chronic toxicity of
D-allose in rats. In the acute toxicity test, the calculated
LD50 value was 20.5 g/kg. In the sub-chronic toxicity
test, no difference was found among the four groups in
most of the serum chemical and hematological test
results. These results suggest that D-allose is not toxic
to rats.
25 g/kg of body weight using a stainless sonde attached
to a 20-ml syringe. The rats were observed for 48 h
after D-allose administration in order to track their
condition and the number of deaths. LD50 values were
calculated from the number of deaths by the Behrens-
Karber method. The rats fasted 12 h after D-allose
administration and were then given free access to CE-2
and water.
Key words: D-allose; toxicity; rat
One rat receiving 17 g/kg, one rat receiving 19 g/kg,
two rats receiving 21 g/kg, three rats receiving 23 g/kg,
and four rats receiving 25 g/kg died within 48 h after
administration. Three rats receiving 15 g/kg, three rats
receiving 17 g/kg, one rat receiving 21 g/kg, three rats
receiving 23 g/kg, and three rats receiving 25 g/kg
suffered from diarrhea within 48 h after administration.
The calculated LD50 value was 20.5 g/kg body weight
as determined by the Behrens-Karber method. This
value is higher than the LD50 value of sucralose (1,6-
dichloro-1,6-dideoxy-ꢁ-D-fructofuranosyl-4-chloro-4-
deoxy-ꢀ-D-galactopyranoside) at doses of 16 g/kg for
mice and 10 g/kg for rats,9) and D-psicose at doses of
16 g/kg for rats.10) Some rats had diarrhea after D-allose
administration. The cause of diarrhea was probably a
rise in osmotic pressure in the large intestine caused by
the absorption obstacle of D-allose. Debility by diarrhea
may have been one cause of rat death. These results
were seen in rats given high doses of D-psicose.10)
In the sub-chronic feeding test, four groups of eight
rats (Ct, A0.3, A1, and A3) were fed CE-2 containing 0,
0.3, 1.0, and 3.0% D-allose, and were given free access to
water for 6 months. The amount test carbohydrate was
decided by reference to previous studies of sucralose and
D-psicose.9,11) Body weight gain and food intake were
recorded every day. After 6 months, the rats were fasted
overnight from 22:00 h, and then sacrificed by exsan-
guinity under anesthetization with intraperitoneal sodium
pentobarbital. Blood was collected from the abdominal
aorta for clinical hematological analysis and to obtain
serum for chemical analysis. The brain, heart, lungs,
liver, pancreas, kidneys, adrenals, spleen, testicles,
intra-abdominal adipose tissues, and hindlimb skeletal
muscles were quickly removed and weighed. Serum
samples were stored at ꢂ20 ꢁC until analysis.
D-Allose, a C-3 epimer of D-glucose, is one of the rare
sugars obtained from the isomerization of D-psicose.1)
Because of the very small amounts of D-allose in natural
products, few studies of D-allose metabolism in animals
have been conducted.
Recently, we developed a new method of producing
D-allose enzymatically on a large scale.1) D-Allose has
been reported to have potential for use in the pharma-
ceutical industry, e.g., as an inhibitor of cancer cell
proliferation2) and in the production of reactive oxygen
species from neutrophils.3) It has been reported that
D-psicose, a precursor of D-allose, suppressed hepatic
lipogenic enzyme activity, reduced abdominal fat
accumulation,4,5) provided no energy to growing rats,6)
inhibited intestinal ꢀ-glucosidase activity, and sup-
pressed the glycemic response,7,8) but D-allose has not
been studied in a nutritional investigation.
In this study, we examined the effects of acute oral
administration and sub-chronic (6 months) feeding of
several levels of D-allose to rats to gather basic data
regarding the safety of D-allose as a nutritional substrate.
All procedures involving animals were approved by
the Experimental Animal Care Committee of Kagawa
University. The values of test results were expressed as
means ꢀ SD. All data were analyzed by one-way
ANOVA and the Tukey-Kramer test. Differences were
considered statistically significant at p < 0:05.
In the acute administration test, male Wistar rats were
obtained from Japan SLC (Shizuoka, Japan). The
animals were caged individually in an automatically
air-conditioned room (temperature, 22 ꢀ 2 ꢁC; humidity,
about 50%) with light from 08:00 to 20:00 h. The rats
were fed CE-2, a commercial rodent diet (CLEA,
Tokyo) before toxicity tests were done.
Serum glucose (Glu), insulin (IRI), triacylglycerole
(TG), total cholesterol (T-Cho), HDL cholesterol (HDL-
Cho), urea nitrogen (UN), uric acid (UA), creatinine
(Crea), albumin (Alb) and total protein (TP) concen-
trations and glutamate oxaloacetate transaminase (GOT)
and glutamate pyruvate transaminase (GPT) activities
D-Allose was prepared from D-psicose with immobi-
lized L-rhamnose isomerase1) and diluted to a 50% water
solution. Seven groups of four rats (5 week old) were
fasted overnight from 22:00 h and were orally given
D-allose in single doses of 15, 17, 19, 21, 23, and
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To whom correspondence should be addressed. Tel: +81-87-891-3082; Fax: +81-87-891-3021; E-mail: matsuo@ag.kagawa-u.ac.jp
Iga, Yusuke
