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EC number: 404-370-8 | CAS number: 126990-35-0 DCPMS; DYNASYLAN 9415; EURENOR 5023; SAN-30; WACKER SILAN CP2-DIMETHOXY; Z-6228
Genetic toxicity: in vitro
Administrative data
- Endpoint:
- in vitro gene mutation study in bacteria
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 4 February to 16 March 1992
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 1 993
- Report date:
- 1993
Materials and methods
Test guidelineopen allclose all
- Qualifier:
- according to guideline
- Guideline:
- JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals
- Deviations:
- no
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 471 (Bacterial Reverse Mutation Assay)
- Deviations:
- yes
- Remarks:
- (only 2 replicate plates/concentration)
- GLP compliance:
- yes
- Type of assay:
- bacterial reverse mutation assay
Test material
- Reference substance name:
- Dicyclopentyldimethoxysilane
- EC Number:
- 404-370-8
- EC Name:
- Dicyclopentyldimethoxysilane
- Cas Number:
- 126990-35-0
- Molecular formula:
- C12H24O2Si
- IUPAC Name:
- dicyclopentyldimethoxysilane
- Test material form:
- liquid
Constituent 1
Method
- Target gene:
- histidine locus (Salmonella typhimurium strains)
tryptophan locus (Escherichia coli WP2 uvrA)
Species / strain
- Species / strain / cell type:
- other: Salmonella typhimurium TA1535, TA1537, TA98, TA100, Escherichia coli WP2 uvrA
- Additional strain / cell type characteristics:
- not applicable
- Metabolic activation:
- with and without
- Metabolic activation system:
- S9 microsomal fraction prepared from phenobarbital- and 5,6-benzoflavone-induced rat liver
- Test concentrations with justification for top dose:
- S. typhimurium strains:
0, 2.4, 4.9, 10, 20, 39 and 78 μg/plate, without S9
0, 2.4, 4.9, 10, 20, 39 and 78 μg/plate, with S9 for TA1535 and TA100
0, 10, 20, 39, 78, 156 and 313 μg/plate, with S9 for TA1537 and TA98
Escherichia coli WP2 uvrA:
0, 313, 625, 1250, 2500 and 5000 μg/plate, with or without S9 - Vehicle / solvent:
- - Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: test material insoluble in water, DMSO is included in the list of recommended solvents
Controlsopen allclose all
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- Remarks:
- DMSO
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- furylfuramide
- Remarks:
- 0.01 μg/plate TA100 and WP2 uvrA; 0.1 μg/plate TA98 (without S9)
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- Remarks:
- DMSO
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- sodium azide
- Remarks:
- 0.5 μg/plate TA1535 (without S9)
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- Remarks:
- DMSO
- True negative controls:
- no
- Positive controls:
- no
- Positive control substance:
- other: 2-methoxy-6-chloro-9-[3-(2-chloroethyl)-aminopropylamino]acridine.2HCl (ICR-191) 1 μg/plate TA1537 (without S9)
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- Remarks:
- DMSO
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- benzo(a)pyrene
- Remarks:
- 5 μg/plate TA100, TA98 and TA1537 (with S9)
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- Remarks:
- DMSO
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- other: 2-aminoanthracene: 2 μg/plate TA1535; 5 μg/plate WP2 uvrA (with S9)
- Details on test system and experimental conditions:
- METHOD OF APPLICATION: preincubation
DURATION
- Preincubation period: 20 min
- Exposure duration: 48 h in plates
SELECTION AGENT (mutation assays): depleted levels of histidine or tryptophan in agar medium to select for mutants
NUMBER OF REPLICATIONS: 2 plates/concentration. 2 independent experiments, but in the second only TA1535, TA1537, TA98 and TA100 were tested without S9 and only TA1535 and TA100 were tested with S9.
DETERMINATION OF CYTOTOXICITY
- Method: relative total growth
OTHER:
- Type and composition of metabolic activation system:
- species and cell type: rat, S9 fraction
- quantity: 0.1 ml S9 fraction per 1 ml S9 mix, 0.5 ml S9 mix per plate
- induced or not induced: incuded
- chemicals used for induction: phenobarbital and 5,6-benzoflavone
- co-factors used: Boehringer Mannheim Yamanouchi KK, lot number 712.713; MgCl2 8.0 μmol; KCl 33 μmol; G6P 5 μmol; NADPH 4 μmol; NADH 4 μmol; Na-phosphate buffer (pH 7.4) 100 μmol. - Evaluation criteria:
- Results considered positive if there was a reproducible increase in the mutant frequency of at least twice that of the solvent control at least one time point, or a concentration-related increase over more than one time point.
- Statistics:
- No data
Results and discussion
Test results
- Species / strain:
- other: S. typhimurium TA1535, TA1537, TA98, TA100, E. coli WP2 uvrA
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- 39 μg/plate in TA100, TA1535, TA1537 without S9; 78 μg/plate in TA98 without S9 and TA100, TA1535 with S9; 313 μg/plate in TA98, TA1537 with S9
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Additional information on results:
- TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: no data
- Effects of osmolality: no data
- Evaporation from medium: no data
- Water solubility: no data
- Precipitation: no data
- Other confounding effects: no data
RANGE-FINDING/SCREENING STUDIES: a range-finding study was conducted with 0, 1.2, 4.9, 20, 78, 313, 1250 and 5000 μg/plate. No growth inhibition was observed with WP2 uvrA. Growth inhibition was noted at 78 μg/plate and above without S9 for all Salmonella strains and with S9 for TA1535 and TA100. Growth inhibition was seen at 313 μg/plate and above with S9 for TA1537 and TA100.
COMPARISON WITH HISTORICAL CONTROL DATA: no data
ADDITIONAL INFORMATION ON CYTOTOXICITY: without S9, cytotoxicity occurred at 78 μg/plate for TA1535, TA98 and TA100 and at 39 μg/plate for TA1537. With S9, cytotoxicity was seen at 78 μg/plate for TA1535 and TA100 and at 156 μg/plate and above for TA1537 and TA98. No toxicity was observed with WP2 uvrA at up to 5000 μg/plate, with or without S9. - Remarks on result:
- other: all strains/cell types tested
Any other information on results incl. tables
A doubling of revertants was seen in the first experiment at 4.9 μg/plate in TA1535 without S9, but this was not observed in the second experiment and, as no increase in mutant frequency was seen at any other concentration level, it was concluded that this was not related to the test material.
Table 1:Number of revertants per plate (mean of 2 plates) – Experiment 1
Bacterial strain |
TA100 |
TA1535 |
TA98 |
||||||
Concentration of test material, |
- MA |
+ MA |
Cytotoxic |
- MA |
+ MA |
Cytotoxic |
- MA |
+ MA |
Cytotoxic |
0* |
104 107 (106) |
104 130 (117) |
no |
11 11 (11) |
16 16 (16) |
no |
26 23 (25) |
31 33 (32) |
no |
2.4 |
122 137 (130) |
141 123 (132) |
no |
16 13 (15) |
13 18 (16) |
no |
18 23 (20) |
no |
|
4.9 |
100 127 (114) |
139 118 (129) |
no |
22 21 (22) |
16 16 (16) |
no |
22 24 (23) |
no |
|
10 |
135 120 (128) |
106 122 (114) |
no |
19 12 (16) |
22 8 (15) |
no |
22 20 (21) |
37 26 (32) |
no |
20 |
105 105 (105) |
102 100 (101) |
no |
15 8 (11) |
14 18 (16) |
no |
20 20 (20) |
30 29 (30) |
no |
39 |
83 84 (84) |
138 128 (133) |
no |
17 10 (14) |
10 13 (12) |
no |
21 23 (22) |
28 23 (26) |
no |
78 |
89 81 (85) |
93 92 (93) |
yes |
13 10 (12) |
17 17 (17) |
yes |
28 20 (24) |
31 24 (28) |
yes –MA no +MA |
156 |
30 29 (30) |
yes |
|||||||
313 |
35 29 (32) |
yes |
|||||||
Positive control |
AF-2 0.01 µg/plate |
B[a]P 5.0 µg/plate |
NaN3 0.5 µg/plate |
2AA 2.0 µg/plate |
AF-2 0.1 µg/plate |
B[a]P 5.0 µg/plate |
|||
800 762 (781) |
896 985 (941) |
417 355 (386) |
213 208 (211) |
401 422 (412) |
181 204 (193) |
||||
Table 1. (cont’d)
TA1537 |
WP2uvrA |
|||||
- MA |
+ MA |
Cytotoxic |
- MA |
+ MA |
Cytotoxic |
|
0* |
13 18 (16) |
19 24 (22) |
no |
24 22 (23) |
29 37 (33) |
no |
2.4 |
21 25 (23) |
|||||
4.9 |
17 19 (18) |
|||||
10 |
17 25 (21) |
26 20 (23) |
no |
|||
20 |
18 9 (14) |
25 21 (23) |
no |
|||
39 |
8 12 (10) |
27 19 (23) |
yes -MA no +MA |
|||
78 |
10 10 (10) |
22 18 (20) |
yes –MA no +MA |
|||
156 |
15 8 (12) |
yes |
||||
313 |
14 19 (17) |
yes |
16 29 (23) |
38 19 (29) |
no |
|
625 |
17 20 (19) |
31 26 (29) |
no |
|||
1250 |
14 33 (24) |
21 15 (18) |
no |
|||
2500 |
20 24 (22) |
23 37 (30) |
no |
|||
5000 |
27 21 (24) |
25 28 (27) |
no |
|||
Positive control |
ICR-191 1.0 µg/plate |
B[a]P 5.0 µg/plate |
AF-2 0.01 µg/plate |
2AA 10.0 µg/plate |
||
1330 1256 (1293) |
84 104 (94) |
138174(156) | 740692(716) | |||
*solvent control (DMSO)
2AA, 2-aminoanthracene; AF-2, furylfuramide; B[a]P,benzo(a)pyrene; MA, metabolic activation; NaN3, sodium azide
Table 2:Number of revertants per plate (mean of 2 plates) – Experiment 2
Bacterial strain |
TA100 |
TA1535 |
TA98 |
||||||
Concentration of test material, |
- MA |
+ MA |
Cytotoxic |
- MA |
+ MA |
Cytotoxic |
- MA |
+ MA |
Cytotoxic |
0* |
99 137 (118) |
101 120 (111) |
no |
17 9 (13) |
24 19 (22) |
no |
16 21 (19) |
no |
|
2.4 |
103 130 (117) |
107 122 (115) |
no |
12 18 (15) |
21 16 (19) |
no |
28 22 (25) |
no |
|
4.9 |
106 111 (109) |
121 99 (110) |
no |
20 17 (19) |
24 18 (21) |
no |
24 16 (20) |
no |
|
10 |
107 118 (113) |
117 132 (125) |
no |
13 18 (16) |
13 19 (16) |
no |
18 21 (20) |
no |
|
20 |
100 112 (106) |
132 96 (114) |
no |
11 14 (13) |
21 20 (21) |
no |
17 22 (20) |
no |
|
39 |
88 125 (107) |
102 119 (111) |
yes –MA no +MA |
8 13 (11) |
17 20 (19) |
yes –MA no +MA |
17 18 (18) |
no |
|
78 |
75 99 (87) |
99 93 (96) |
yes |
17 9 (13) |
17 9 (13) |
yes |
20 22 (21) |
yes |
|
Positive control |
AF-2 0.01 µg/plate |
B[a]P 5.0 µg/plate |
NaN3 0.5 µg/plate |
2AA 2.0 µg/plate |
AF-2 0.1 µg/plate |
||||
768 784 (776) |
821 819 (820) |
397 395 (396) |
226 214 (220) |
417 412 (415) |
|||||
Table 2. (cont’d)
TA1537 |
|||
- MA |
+ MA |
Cytotoxic |
|
0* |
11 9 (10) |
no |
|
2.4 |
18 16 (17) |
no |
|
4.9 |
13 11 (12) |
no |
|
10 |
9 10 (10) |
no |
|
20 |
8 11 (9) |
no |
|
39 |
8 9 (9) |
yes |
|
78 |
7 4 (6) |
yes |
|
Positive control |
ICR-191 1.0 µg/plate |
||
1208 1110 (1159) |
|||
*solvent control (DMSO)
2AA, 2-aminoanthracene; AF-2,furylfuramide; B[a]P,benzo(a)pyrene; MA, metabolic activation; NaN3, sodium azide
Applicant's summary and conclusion
- Conclusions:
- In a reliable and valid gene mutation study in bacteria, conducted according to Japanese guidelines with a protocol similar to the OECD Test Guideline 471 and in compliance with GLP, dicyclopentyl(dimethoxy)silane did not induce mutagenic activity in Salmonella strains (Salmonella typhimurium TA1535, TA1537, TA98, TA100) at up to 313 μg/plate (limited by cytotoxicity) and in Escherichia coli (WP2 uvrA) at up to 5000 μg/plate, with and without S9.
- Executive summary:
In a GLP study conducted according to Japanese guidelines, DCPMS was evaluated for its ability to induce mutation in a bacterial reverse mutagenicity (Ames) assay in four strains of Salmonella typhimurium and Escherichia coli WP2 uvrA, with and without a rat metabolic activation fraction (S9).
After a range-finding study, the S. typhimurium strains were exposed in a preincubation assay to the test material at up to 78 μg/plate without S9 (all four strains) and with S9 for TA1535 and TA100; at up to 313 μg/plate for TA1537 and TA98; E.coli WP2 uvrA was tested at up to 5000 μg/plate both with and without S9. The solvent, DMSO, was used as the vehicle control and appropriate known mutagens provided the positive controls. Plates were prepared in duplicate and incubated for 48 hours before counting the revertant colonies. Inhibition of the background lawn was noted as an indication of cytotoxicity. A second independent experiment was conducted, at up to 78 μg/plate using the four Salmonella strains without S9 and TA1535 and TA100 with S9.
No reproducible, concentration-related increase in mutant frequency was observed with any bacterial strain at any concentration of the test material, when compared to the solvent control. The positive controls induced the expected increases in mutant frequencies, confirming the validity of the assay. A thinning of the background lawn at the higher concentrations with the Salmonella strains indicated that the test material was cytotoxic to these strains but not to WP2 uvrA.
Under the conditions of this study, DCPMS showed no mutagenic potential in a bacterial reverse mutagenicity (Ames) assay with four strains of S. typhimurium and E. coli WP2 uvrA
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