GLUCOSE ISOMERASE
(isolated from Streptomyces violaceoniger)
Systematic name: D-Glucose-ketolisomerase (E.C. 5-3-1-18)
Explanation
Streptomyces violaceoniger - glucose isomerase is an enzyme
obtained through an industrial cultivation of a strain of
Streptomyces Violaceoniger (strain number CES 409-73). This enzyme
catalyses the transformation of D-glucose to D-fructose.
BIOLOGICAL DATA
TOXICOLOGICAL STUDIES
Special study on reproduction
Isomerized glucose (42-43% fructose 53-56% glucose) was
administered in drinking water to three successive generations of
rats. The results have been compared to those obtained on animals
receiving inverted saccharose under the same conditions.
The test substance was administered in the drinking water as an
aqueous solution at 10% to two groups. Each group consisted of 10
males and 20 females (F0 generation) which after 10 weeks were mated
twice in order to obtain F1a and F1b generations. At weaning of F1a,
10 males and 20 females per group were retained and mated, when adult,
to produce, the F2a and then the F2b generations. F3a and F3b were
produced from the F2a generation, for which, at weaning, 10 males and
20 females were selected. F3b was observed until 8 weeks of age and
sacrificed. The growth of the F3b generation during the 8 weeks of
treatment after weaning was normal in the two groups. Main organs of
10 males and 10 females per group were examined histologically.
Results obtained with inverted saccharose (group I) and with
isomerized glucose (groupe II) were comparable. The occasional
differences observed between groups I (inverted saccharose) and II
(isomerized glucose) during the production of 6 litters (2 in each of
the three generations) were incidental. The average number of pups per
litter was 10.12 (group I), and 10.97 (group II) with a mean weight at
birth of 6.79 and 6.73 g. Neo-natal and post-natal mortality and
growth rate were comparable in both groups. No behavioural change has
been observed during the three generations study.
The production of two successive litters of the F0, F1 and F2a
generations showed no abnormalities in the reproductive process.
No adverse effect of the coadministration of either carbo-hydrate
was observed on fertility, reproductive performance, birth weight
(growth in utero).
In conclusion, in this experiment no effect on reproduction was
observed when isomerized glucose is administered at the dose level of
20 g/kg/day/rat (IFREB, 1978).
Acute toxicity
From a tube of agar sown with Streptomyces violaceoniger
(strain CBS 409 - 73) 200 ml of culture in broth (dextrose 5%) was
prepared. Half this broth was filtered and the filtrate injected
intravenously in 10 mice at 0.2 ml per mouse (10 other control mice
received the same volume (0.2 ml) of non used broth) without
streptomyces.
The rest of culture suspension was injected intraperitoneally
into 10 mice (SPF - Strain OF1) at 0.5 ml/mouse (here too 10 control
mice received the same 0.5 ml of non used broth intraperitoneally).
The 40 animals were kept under observation for two weeks. No
mortality resulted, and behaviour was normal. After two weeks the mean
weight gain was 0.8 to 1.4 g per animal.
It can be concluded that neither pathological effects, nor the
presence of exotoxins were shown in the mouse by this treatment.
Subchronic studies
Groups of rats composed of 10 males and 10 females were submitted
to diets containing isomerized glucose (42-43% fructose 53-56%
glucosel) and/or Streptomyces (lysed and atomised) in an active or
inactive form.
The isomerized glucose was administered in the drinking water at
a concentration of 10% dry weight, and the atomised Streptomyces in
the food at 5%.
A group of rats I was fed with a control diet and the other
groups received: II control diet but drinking water containing 10% of
invert sugar, i.e. 13.5% of syrup; III control diet containint 5% used
Streptomyces and drinking water containing 13.5% enriched, unrefined
isomerized glucose syrup; IV enriched unrefined isomerized glucose,
13.5% in drinking water (to give 10% of sugar); V a diet containing 5%
powder of active non utilised Streptomyces; VI a diet containing 5%
powder of utilised Streptomyces.
After four weeks of treatment were conducted the following
observations; haematology, biochemical and urine analyses, post-mortem
and histological examinations of the principal organs.
No toxicity was demonstrated by the observations and examinations
carried out. There was no detectable abnormality in behaviour.
Isomerized glucose obtained and the microorganism used for its
preparation produced no toxic effect in rats (IFREB).
Short-term studies
Four groups of rats (10 M and 10 F) received for 90 days in
drinking water at 10% invert sugar commercial isomerized glucose
(42-43% fructose 53-56% glucose) raw isomerized glucose and the last
group received at the same condition row isomerized glucose and
Strpetomyces violaceoniger at 2.5% in the diet. Haematological,
biochemical and urine analyses and histopathology were performed at
the end of the treatment. The results were comparable in the four
groups. There was no detectable abnormality in behaviour and in the
weight gain. So isomerized glucose obtained from glucose and the
micro-organism used for its preparation produced no toxic effects in
rats (IFREB).
Long-term studies
Two groups of rats received for two years a syrup containing
isomerized glucose (42-43% fructose 53-56% glucose). One group was
given raw isomerized glucose and the other one commercial isomerized
glucose, both at 10% in drinking water. A third group (control group)
received a chemically comparable product: invert saccharose at the
same conditions. Each of the three groups consisted of 50 male and
female OFA, Sprague-Dawley originated rats. Haematology, clinical
chemistry and urine analyses were performed during the course and at
the end of the experiment. All moribund animals were sacrificed and
necropsied; all survivors were sacrificed after 23 months of treatment
on account of the survival rats at this stage.
The sugared fluid being administered ad libitum, a high fluid
consumption was observed. The general over-consumption of energetic
material has possibly induced the slightly earlier mortality than
usually observed and which was comparable in the three groups.
No significant differences were observed in blood and urinary
parameters examined during the trial between the control and the two
treated groups. No significant difference has been noted between group
I and groups II and III as far as histological examination is
concerned.
In conclusion, in this experiment no toxic effect was observed
when isomerized glucose is administered at the dose level of about
15 g/kg/day (IFREB, 1978).
Comments
A three generation rat reproduction study carried out with
isomerized glucose (42-43% fructose 53-56% glucose) obtained from
glucose through the Streptomyces violaceoniger glucose isomerase
showed that indices of fertility gestation, live birth litter size at
weaning as well as the appearance behaviour, physical examination data
and gross necroscopy were comparable to control group (invert sugar).
No effect on reproduction was observed when isomerized glucose
was administered in drinking water at the dose level of 20 g/kg/day.
When commercial isomerized glucose (10%), raw isomerized glucose (10%)
and raw isomerized glucose (10%) added with 2.5% Streptomyces
violaceoniger were administered in drinking water to rats for three
months, no significant differences were found from the control group
(invert sugar 10%).
Long-term study on rats using isomerized glucose (10%) obtained
with the Streptomyces violaceoniger enzyme preparation showed no
toxic effect at the dose level of about 15 g/kg/day.
EVALUATION
Estimate of an acceptable daily intake for man
Not specified.
REFERENCES
IFREB (undated) 1 month inocuity trial in the rat of the product and
intermediate substrates. Unpublished report from Institut français de
Recherche et Essais biologiques. Submitted to the World Health
Organization by Roquette Frères.
IFREB (undated) Pathogenecity study on Streptomyces violaceoniger.
Unpublished report from Institut français de Recherche et Essais
biologiques. Submitted to the World Health Organization by Roquette
Frères.
IFREB (1975) Three months oral toxicity study. Unpublished report from
Institut français de Recherche et Essais biologiques. Submitted to the
World Health Organization by Roquette Frères.
IFREB (1978) Three generation study in rats with isomerized glucose.
Unpublished report from Institut français de Recherche et Essais
biologiques. Submitted to the World Health Organization by Roquette
Frères.
IFREB (1978) Two years oral carcinogenicity study in rats with
isomerized glucose prepared with the glucose isomerase lysase G1.
Unpublished report from Institut français de Recherche et Essais
biologiques. Submitted to the World Health Organization by Roquette
Frères.
See Also:
Toxicological Abbreviations