Environmental and Molecular Mutagenesis - Legacy Tobacco ...

289
CHARACTERISTIC PEROXIDASE-MEDIATED DNA-ADDUCTS OF BENZO(a)PYRENE AND OF DIESEL
EXHAUST PARTICULATE EXTRACT .
R . Kind, D . Wild, D. Henschler, Institute of Toxicology, University of WOrzburg,
Wurzburg, Fed . Rep . of Germany
It is our aim to elucidate the potential of peroxidases for the metabolic
activation of Diesel motor exhaust components . While the monooxygenase (MO)dependent
activation of PAHs and Diesel emissions and the resulting genotoxic
effects have been investigated frequently, little is known about the peroxidasedependent
activation . We have used benzo(a)pyrene (HaP) and Diesel particulate
extract (DPF~)2and 2 techniques to assay peroxidase-mediated reactive metabolites
: 1 . P-postlabeling assays for DNA binding metabolites and 2 . Salmonella/peroxidase
assays for mutagenic metabolites . Horse radish peroxidase and
bovine lactoperoxidase were used. For the adduct studies, calf-thymua DNA was
exposed to BaP or DPE, peroxidase and H202. The DNA was analyzed for adducts by
postlabeling, 2-dimensional TLC on PEI-cellulose and autoradiography . For comparison,
analogous experiments were performed using MOs (PCB-induced rat liver
S9 and NADPH) . Peroxidase-dependent BaP adduct spots were clearly demonstrated .
Similarly, DPE was activated by peroxidases and produced prominent adducts and a
diffuse adduct zone . A different adduct-pattern was seen following activation by
MO . On the other hand, peroxidase-mediated mutagenic effects were not found . We
conclude that peroxidases produce characteristic DNA-binding metabolites which
are probably short-lived and cannot reach the Salmonella DNA target . These
metabolites may however be relevant for cells with endogenous peroxidase activity.
* Supported by BMFT and FAT *
290
DIPSffiNTLBZDANTOIM IS NEGATIVE IN A bATTER2 OF SHORT SBM ClTOGBN6IIC ASSAYS .
D . Kindig, J . Beyers*, J . Erunny, J . Parton, and M . Garriott, Lilly Research
Laboratories, Eli Lilly and Company, Greenfield, IN 46140
5,5-Diphenylhydantoin (DPH) is an antiepileptic drug associated vith an
increase in malformations in offspring of vomen vho took DPH during pregnancy . When
DPH has been tested in genetic toxicology studies, the•results have been varied .
Positive and negative results have been reported for in vivo and in vitro chromosome
aberration (CAB) assays, in vivo and in vitro sister cTiromatid exc7isngi TSCE)
assays, and in vivo micronucieus tests (W. This report presents results obtained
from a battery oF Lests performed in a single cytogenetics laboratory . DPA vas
tested in the in vitro CAB assay using Chinese hamster ovary cells at doses of 200,
250, and 300 ug7mwfih and vithout an S-9 activation system . The percentage of
aberrations ranged from 2 to 4 and from 0 to 1 vith and vithout activation,
respectively, and there vas no significant increase in aberrant cells vhen compared
vith the solvent control . The SCE assay used intraperitoneal doses of 5, 10, 20,
and 40 mg/kg and bone marrovi cells from CD-1 female mice vere harvested 21 hours
after dosing . The incidence of SCEs ranged from 3 .7 to 4 .5 SCEs per metaphase .
There vas no increase in the number of SCEs in DPB-treated animals vhen compared to
solvent controls . For evaluation in the MNT, intraperitoneal doses of 10, 20, and
40 mg/kg vere administered to ule and female CD-1 mice . Bone marrov vas extracted
from the femurs 24 hours after dosing . The frequency of micronucleated
polychromatic erythrocytes ranged from 1 .4 to 2 .6 and did not reflect an inerease
over the solvent controls . The results from this battery of tests indicate that the
knnvn tPintnqen, DPH, is nonmutagenic .
291
INVESTIGATIONS ON THE EXTENT 0! TESTING REQUIRED TO EXCLUDE NON-CL)1STOGEtiB IN ROUTINE
GHROMOSOHAL ABERRATION TESTS . D .J . Kirkland, M . Ishidate Jr, D . Gatehouae and
C . Richardson . Microtest Research Limited, York, UK ; National Institute of Hygienic
Sciences, Tokyo, Japan ; Glaxo Group Research, Ware, Herts, UK and ICI Central Toxicology
Laboratory, Macclesfield, Cheshire, UK .
A number of clastogens seem to require 48 hr treatments - 8-9 in CFRL cells to produce
a positive response . 4 chemicals from Ishidate's Data Book (Elsevier, 1988) which
were negative at the same doses after 24 hr - 8-9, were retested at the same or higher
doses, but also with 6 hr treatment (- and + S-9) followed by 18 hr recovery (6-18),
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
1989 EMS Abstracts 101
Notes