Environmental and Molecular Mutagenesis - Legacy Tobacco ...

72 1989 EMS Abstracts 203
Notes GENETIC TOXICITY TESTING OF CHLORPYRIFOS AND ITS MAJOR METABOLITE
B . B . Gollapudi, J . A . Zempel, A . L . Mendrala, V . A . Linscombe, M . L . McClintock,
and A . K . Sinha, The Dow Chemical Company, Health and Environmental Sciences,
Freeport, TX 77541, and Mammalian and Environmental Toxicology Research Laboratory,
Midland, MI 48674 .
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
The genotoxic potential of the organophosphate insecticide chlorpyrifos [Q,Qdiethyl-Q-(3,5,6-trichloro-2-
pyridyl)phosphorothioate, C .A .S . ! 2921-88-2j and its
major metabolite, 3,5,6-trichloro-2-pyridinol (C .A .S . I 6515-38-4) were evaluated in
a battery of short-term assays consistiny of Ames, UDS, CHO/HGPRT, and the mouse
bone marrow micronucleus tests . In the Anes test, the chemicals did not elicit a
positive response in the Salmonella typhimurium tester strains TA98, TA100, TA1535,
TA1537, and TA1538 either in the presence or absence of an externally supplied
metabolic activation system (Aroclor 1254-induced rat liver S9) . Hepatocytes
collected from male Fischer 344 rats (11-15 weeks old) were treated in vitro with
the test chemicals in the presence of H-thymidine and the extent of UDS was
quantitated by autoradiography . Neither chemical induced a positive UDS response .
No significant increases in the frequency of TGr colonies were observed in the
CHO/HGPRT assay after treatment of CHO-K' -8H4 cells with the test chemicals either
in the presence or absence of S9 . Administration of the test chemicals by oral
gavage to CD-I mice did not increase the frequency of micronucleated bone marrow
polychromatic erythrocytes . These results suggest lack of genotoxic potential for
the test chemicals .
204
MOLECULAR ORBITAL AND GEOMETRICAL STRUCTURE DESCRIPTORS IN GSAR STUDIES : MUTAGENICITY
OF SOME AMINO- AND NITRO-BENZENES
V .K . Gombar, K . Enalein
Health Designs, Inc ., 183 East. Main Street, Rochester, NY 14604
Topology-based structure quantifiers are commonly employed In QSAR studies for the
ease and speed of their computation . They, however, by definition, do not encode
structural information pertaining to the spatial arrangement of atoms . A study has been
conducted to investigate the importance of descriptors derived from three-dimensional
atomic coordinates in QSAR models . A set of 43 amino- and nitro-benzenes (X- 0-NYZ)
tested for mutagenic response of Salmonella tester strain TA100 (rat liver S-9, Aroclor
1254 induced) has been selected for the study . Twenty-aix of these were labeled +ve and
17 -vP . The geometry-based parameters investigated Include shape parameters viz .
molecular surface area and volume, principal moments of inertia, etc . and electronic
parameters such as Atomic charges, dipole moment, orbital energies, etc . Topological
shape descriptors K (kappa) give a poor correlation (n = 40 ; m- 5 ; r z 0 .486) . A
marginal improvement is observed with group surface area and volume (n : 40 ; m c 5 ;
r = 0 .583) . However, the two types combined yield a significant improvement (n a 40 ;
m = 8 ; r = 0 .738) . Similar comparison of QSAR equations obtained using other electronic
and geometrical descriptors will also be presented .
205
DEVE)APMRNT OF' AN IMMUNOASSAY TO MONITOR EXPOSURK TO REN7.O(n)PYRENH BY MHASUREMF.NT OF
URINARY METABOLITES M . Gomes, T . Vo--Dinh and R . M . Santclla, Oak Ridge National
Laborat.ories, Oak Ridge, TN (USA) and Columbia University, New York, NY (USA)
The aim oi' this study was to develop an i.munoassay to monitor human exposure to
benzo(a)pyrene (Bt') by meaaure.ment of BP and its metabolites in urine . A monoclonal
antibody was produced from the spleen cells of Balb/c mice immunized with 6-amino-BP
covalently coupled to bovine serum albumin . The most sensitive antibody, 4U5, was
characterized in terms of sensitivity and specificity by competitive enzyme-linked
immunosorbentt assay (ELISA) . The antibody recognizes BP (50% inhibition at 4 pmolo) as
well as a number of BP metabolites . With BP phenols including 1-OH, 3-OH, 4-OH and 5-
OH, 50% inhib .ition occurs at. 20 . 90, 60, and Hpmol, respectively . With BP-1,8--diol
and 9,10-diol and 7,6,9,10-tetraol, 50% Lnhibition is at 1 .4, 4 .5 and 1 .0 paolo,
respectively . Crossreactivity was also seen with several other polycyclic aromatic
hydrocarbons (PAHs) including pyrene (60% inhibition at 1 .6pmol), 1-aminopyrene (60%
inhibition at 0 .49pmo1) and 7,12-dimethylbenz(n)anthrecene (50% inhibition at 67pmol) .
These results indicate that this assay will detect multiple PAH metabolites .
Validation of the assay was carried outt on ∎ice treated with [3H) RP . Urine was
treated with beta--glucuronidase and arylsulfatase and BP and its metabolites isolated
by affinity chromatography on ScpPek cartridges . Samples were counted and analyzed by
competitive ELISA using BP in the standard curve . These studies indicated that the
imaunoassay detected about 54% of the adducte measured by radioactivity . This assay
will be used to analyze urines from populations with high exposure to PAHs including
BP . Because of the broad specificity of the antibody, absolute quantitation of PAH
metabolites may not be possible . This work was supported by a grant from NIOSH-02622 .
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