N-octadecyl mercaptan (ODM)
A mutagenicity screening of n-octadecyl mercaptan (ODM) using the algorithm described in
the toolbox is explained below step by step.
Step 1: Substance identification
To avoid repetition, see the endocrine disruptor screening report for ODM as this step is the
same.
Step 2: Data needed for the assessment
These are divided into the followings:

In vitro or in vivo data gene mutation

In vitro or in vivo data on Cytogenetic evaluation of chromosomal damage or DNA

In vitro or in vivo data on cell transformation
Step 3: Collecting the available information
Conducting searches in the Mutagenicity sources and databases listed in step 3 of the
algorithm for ODM revealed no citation in this topic. In other word, no data related to ODM
with regards to its mutagenicity.
Step 4: Using (Q)SAR models
In this step the ability of ODM to be a mutagen was predicted. Two computer programs were
used to predict the Ames bacterial mutagenicity endpoint, these were the DEREK expert
system software and Multicase (through the Danish (Q)SAR database). The results from all
the (Q)SAR models were combined to reach a conclusion.
1- Results obtained by using DEREK:
The analysis by the DEREK system is carried out by screening the structure against the
structural alerts for mutagenic effects described in the DEREK knowledge base. The result is
then presented on the screen; toxophores are highlighted sequentially and displayed along
with their associated toxic effect (Figure. 1). The basis for each prediction can be readily
obtained by activation of a REFERENCE button. This provides a summary of the current
active rule together with key literature references used to derive it. Accordingly, ODM was
predicted by DEREK to be Ames-negative. No structural alerts associated with mutagenicity
were identified as shown in Figure 1 below.
Figure 1: DEREK window output for ODM.
2- Results obtained from Danish (Q)SAR database
The Danish (Q)SAR report for N-Octadecyl mercaptan is shown below (Figure 2) with some
comments. This output contains predictions for physical-chemical, environmental and human
health endpoints, however, as we are only interested in mutagenicity endpoints these are
highlighted in blue. In particular the Ames bacterial mutagenicity endpoint is the one
essential for this assessment and this is highlighted in red. The highlighted text indicates the
values predicted using Multicase software. Unfortunately the prediction output of ODM by
multicase cannot be presented in this report for commercial purposes only the final prediction
is shown.
Figure 2: Danish(Q)SAR report for N-Octadecyl mercaptan
After checking that ODM fits the Multicase Ames-model domain (see the red highlight) the
prediction can then be taken into account. ODM was predicted to be Ames-negative
compound (not mutagen).
By comparing the predicted values obtained from DEREK program with the Danish(Q)SAR
database (Multicase), we could conclude that ODM is unlikely to be mutagen. We need to
cross validate this finding with an in vitro test to reach a final conclusion.
Step 5: carrying out in vitro tests
The green screen assay (Gentronix) did not show any genotoxicity. The lowest concentration
tested was 3.91 µg/ml and the maximum 1000 µg/ml.
Step 6: Is the information I have sufficient to identify the hazard?
Identifying the hazard of ODM being potential mutagen is based on the genotoxicity data in
particular gene mutation and induction of DNA-repair activity. Two models for Ames
mutagenicity were used to predict the gene mutation endpoint for ODM, DEREK and
Mutlicase respectively. Both models estimated that ODM is unlikely to be a mutagen.
Additional support for the prediction was obtained by assessing the genotoxicity of ODM
using GreenScreen assay (Gentronix). In agreement with the predicted data, this study did not
show any genotoxicity of ODM.
As a conclusion, based on the prediction and measured data, ODM is not considered to be
potential mutagen.
Summary
This report presents the results from a (Q)SAR and in vitro tests to identify the hazard of
ODM being potential Mutagen. The (Q)SAR quick screening was only for an Ames bacterial
mutagenicity endpoint using expert system DEREK and multicase software while the in vitro
test was for the induction of DNA-repair activity using Green Screen assay.