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EC number: 232-800-2
CAS number: 9025-57-4
was assayed for mutation in four histidine-requiring strains of S.
typhimurium, and one tryptophan-requiring strain of E. coli both in the
absence and presence of metabolic activation by a metabolic activation
system (S-9 mix), in two separate experiments. A modified ‘treat and
plate’ methodology was used for all treatments in this study. All
xylanase treatments in this study were performed using formulations
prepared in water for irrigation (purified water).
1 treatments used a final (nominal) concentration of 16, 50, 160, 500,
1600, and 5000µg
TOS/mL Experiment 2 a narrowed concentration intervals were employed
covering the range 160-5000µg
TOS/mL in order to examine more closely those concentrations approaching
the maximum test concentration. Following all treatments there were not
clear evidence of toxicity.
xylanase treatment of all the test strains in the absence and presence
of S-9, no clear and concentration-related increases in revertant
numbers were observed that were≥2-fold
(in strains TA98, TA100 and WP2 uvrA pKM101) or≥3-fold
(in strains TA1535 and TA1537) the concurrent vehicle control. This
study was therefore considered to have provided no evidence of any
xylanase mutagenic activity in this assay system.
on the results obtained in this study and under the assay conditions
applied, it is concluded that xylanase is not mutagenic in the Ames test.
objective of this assay was to investigate the potential of xylanase to
induce numerical and/or structural changes in the chromosome of
mammalian systems (i.e., Chinese Hamster V79 cells) in both the presence
and absence of metabolic activation (induced rat liver; S-9 mix). This
assay was conducted in accordance with OECD guideline No. 473 and
complied with GLP.
preliminary cytotoxicity test was performed as a dose range finder using
9 concentrations of xylanase and a solvent and a positive control. Doses
selected for the main tests (Experiment I and II) were based on
cytotoxicity, which was characterized by the percentage of mitotic
suppression in comparison to controls. In the preliminary assay, clear
cytotoxicity was noted at the dose ≥2032.5 µg total organic solids
(TOS)/mL without S9 mix and at the dose ≥2710.0 µg total organic solids
(TOS)/mL with S9 mix. Therefore, the following doses were selected for
the evaluation of the cytogenetic damage in two experiments, Experiment
I, 1016.3 – 1355.0 – 2032.5 µg TOS/mL without S9 and 2032.5 – 2710.0 –
3387.5µg TOS/mL with S9, and Experiment II: 1016.3 – 2710.0 – 3387.5 –
4065.0 µg TOS/mL (without S9). The 5000 µg TOS/mL is the highest dose
recommended by the OECD guideline.
Experiment I, the exposure period was 4 hours for assays with and
without S-9 mix. In Experiment II, the exposure period was 18 hours
without S-9 mix. In both experiments, colcemid was added to the cultures
2.5 hours prior to harvesting. Cells were then harvested, collected,
suspended, fixed, and evaluated.
study, in both experiment I and II, cytotoxicity was observed, however
no biologically relevant increase in the number of cells with structural
chromosomal aberrations was observed. No evidence of an increase in
polyploidy metaphases was recorded with the test article. Significant
increases in structural chromosomal aberrations were found with the
positive controls, ethylmethane sulfonate for assays without S-9 mix and
cyclophosphamide for assays with S-9 mix.
is to be classified as “Non-Clastogenic” in this in vitro cytogenetic
test using cultured Chinese Hamster V79 cells both in the presence and
absence of metabolic activation.
Classification: Not classified
Xylanase was tested in an in vitro
micronucleus assay using duplicate human lymphocyte cultures prepared
from the pooled blood of two male donors in a single experiment.
Treatments covering a broad range of concentrations, separated by narrow
intervals, were performed both in the absence and presence of metabolic
activation (S-9) from Aroclor 1254-induced rats. The test article was
formulated in water for irrigation (purified water) and the highest
concentration tested in the Micronucleus Experiment, 5000 μg TOS/mL was
determined following a preliminary cytotoxicity Range-Finder Experiment.
Treatments were conducted 48 hours following mitogen stimulation by
phytohaemagglutinin (PHA). The test article concentrations for
micronucleus analysis were selected by evaluating the effect of Xylanase
on the replication index (RI). Three concentrations, covering an
appropriate range of cytotoxicity, were selected for scoring of
All acceptance criteria were
considered met and the study was therefore accepted as valid.
Treatment of cells with Xylanase in
the absence and presence of S-9 resulted in frequencies of MNBN cells
which were similar to and not significantly higher than those observed
in concurrent vehicle controls for all concentrations analyzed (all
treatments). With the exception of a single replicate culture at the
lowest and intermediate concentrations analyzed post 3+21 hour +S-9
treatment, the MNBN cell frequency of all Xylanase treated cultures (all
concentrations) fell within the normal range. There were no indications
of any test article concentration related effect on MNBN cell frequency
(negative Cochran-Armitage trend).
was concluded that Xylanase did not induce micronuclei in cultured human
peripheral blood lymphocytes following treatment in the absence and
presence of a rat liver metabolic activation system (S-9).
Concentrations were tested up to 5000 μg TOS/mL, a recommended
regulatory maximum concentration for in vitro micronucleus assays.
The present test substances, three different amylases belonging to
the same subclass of glycosidases (IUBMB class 3.2.1.) as the target
material xylanase and further one lipase, belonging to the IUBMB class
220.127.116.11, have been tested in in vitro gene mutation studies in L5178Y
mouse lymphoma cells. All tests have been performed according to current
OECD guidelines, and in compliance with GLP. No evidence for genetic
toxicity was observed. This supports the conclusion that the target
substance xylanase IUBMB 18.104.22.168 is not genotoxic.
is concluded not to be genotoxic.
M. W., and Johnson, E. A. (2001). Evaluating the Safety of Microbial
Enzyme Preparations Used in Food Processing: Update for a New Century.
Regulatory Toxicology and Pharmacology, 33: 173-186.
The present test substance, xylanase IUB 22.214.171.124, has been investigated
in three in vitro test systems, the Ames test, the in vitro chromosome
aberration test and in a cultured human peripheral blood lymphocyte
micronucleus assay. All tests have been performed according to current
OECD guidelines, and in compliance with GLP. No evidence for genetic
toxicity was observed. The production strains of xylanase meet the
criteria for safe strain production micro-organisms.These results are
supported by read-across from four in vitro gene mutation studies in
L5178Y mouse lymphoma cells performed on three different amylases
belonging to the same subclass of glycosidases (IUBMB class 3.2.1.) as
xylanase and further one lipase, belonging to the IUB class 126.96.36.199.
the lack of genetic toxicity xylanase is not classified.
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