Introduction
Pesticides and heavy metals are of a major environmental concern because of their use in agriculture, industry and public health program (Waliszewski et al., 1996). Glyphosate was shown to induce DNA adducts in mice (Peluso et al., 1998). Paraquat is known chiefly as a pulmonary toxicant and a nurotoxicant in humans (Hughes, 1988). Cadmium toxicities result from its interaction with nucleic acid to form its internal destabilizing complexes (Nordberg et al., 1982). Enzymatic activities could be used as bioindicators for the toxicity of pesticides and heavy metals in vitro (Sekeroglu et al., 1997; El-Demerdash & El-Agamy, 1999). Therefore, the present study was aimed at evaluating the in vitro toxicity induced by paraquat, glyphosate and CdCl2 on serum enzymes as well as monitoring the cahnges in electrophoretic behaviour of serum proteins.
Methods
Glyphosate, paraquat and CdCl2 were used in the present study. Serum pool was obtained from healthy subjects. The activities of serum AST, ALT, AChE, LDH, AlP and AcP were assayed by the methods of Reitman & Frankel (1957), Ellman et al. (1961), Cabaud & Wroblewski (1958), Principato et al (1985) and Moss (1984), respectively. Chemical solutions were added to the serum samples in different concentrations (at 37 °C for an hour). The activity of each enzyme in the samples was measured. Native-polyacylymide gel electrophoresis was carried out using the discontinuous buffer system as described by Laemmli (1970).
Results
The present study showed that ghyphosate was effective on all enzymes except AcP. Its IC50 values were 71.4, 54.2, 270.8, 750 and 714.3 mM for AlP, AST, ALT, LDH, AChE, respectively. The IC50 values of paraquat were 750 and 321.4 mM for ALT and AST, respectively. It had mild effect on LDH and AChE; and no effect on AcP and AlP. The effect of CdCl2 was pronounced with AlP, AcP, AST and AChE, and no effect on ALT and LDH was found. The IC50 values were 33.3, 83.3, 22.2 and 77.7 mM for AlP, AcP, AST and AChE, respectively. Polyacrylamide gel electrophoretic patterns of serum protein showed marked differences with CdCl2 and ghyphasate and not paraquat.
Conclusions
From the results obtained, inhibition of enzymes will enable the development of a sensitive biomarker for the assessment of pesticides and heavy metals toxicity.
References
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Hughes, J. T. 1988. Brain damage due to paraquat poisoning: A fatal case with neuropathological examination of the brain. Neurotoxicology 9,243-248.
Peluso, M., Munnia, A., Bolognesi, C., & Parodi, S. 1998. 32P-postlabeling detection of DNA adducts in mice treated with the herbicide Roundup. Environ. Mol. Mutagen 1,55-59.
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