Evaluation of the serum catalase and myeloperoxidase activities in chronic arsenic-exposed individuals and concomitant cytogenetic damage

Abstract

Chronic arsenic exposure through contaminated drinking water is a major environmental health issue. Chronic arsenic exposure is known to exert its toxic effects by a variety of mechanisms, of which generation of reactive oxygen species (ROS) is one of the most important. A high level of ROS, in turn, leads to DNA damage that might ultimately culminate in cancer. In order to keep the level of ROS in balance, an array of enzymes is present, of which catalase (CAT) and myeloperoxidase (MPO) are important members. Hence, in this study, we determined the activities of these two enzymes in the sera and chromosomal aberrations (CA) in peripheral blood lymphocytes in individuals exposed and unexposed to arsenic in drinking water. Arsenic in drinking water and in urine was used as a measure of exposure. Our results show that individuals chronically exposed to arsenic have significantly higher CAT and MPO activities and higher incidence of CA. We found moderate positive correlations between CAT and MPO activities, induction of CA and arsenic in urine and water. These results indicate that chronic arsenic exposure causes higher CAT and MPO activities in serum that correlates with induction of genetic damage. We conclude that the serum levels of these enzymes might be used as biomarkers of early arsenic exposure induced disease much before the classical dermatological symptoms of arsenicosis begin to appear.

Fig.1

Correlation between arsenic concentration in water and urine and specific activities of the enzymes studied. 1A. Graph showing scatter plot of arsenic concentration in water vs. specific activity of serum catalase. 1B. Graph showing scatter plot of arsenic concentration in urine vs. specific activity of serum catalase. 1C. Graph showing scatter plot of arsenic concentration in water vs. specific activity of serum myeloperoxidase. 1D. Graph showing scatter plot of arsenic concentration in urine vs. specific activity of serum myeloperoxidase. Trendline has been provided in each graph as also the value of the correlation coefficient (r).

Fig.2

Correlation between specific activities of the enzymes studied and induction of DNA damage. 2A. Graph showing scatter plot of specific activity of serum catalase vs. CA/cell. 2B. Graph showing scatter plot of specific activity of serum catalase vs. % of aberrant cells. 2C. Graph showing scatter plot of specific activity of serum myeloperoxidase vs. CA/cell. 2D. Graph showing scatter plot of specific activity of serum myeloperoxidase vs. 5 of aberrant cells. Trendline has been provided in each graph as also the value of the correlation coefficient (r).

Fig.3

Correlation between arsenic concentration in water and urine and induction of DNA damage. 3A. Graph showing scatter plot of arsenic concentration in water vs. CA/cell. 3B. Graph showing scatter plot of arsenic concentration in water vs. % of aberrant cells. 3C. Graph showing scatter plot of arsenic concentration in urine vs. CA/cell. 3D. Graph showing scatter plot of arsenic concentration in urine vs. % of aberrant cells. Trendline has been provided in each graph as also the value of the correlation coefficient (r).