ABSTRACT
The air pollution effects on the activity of antioxidant enzymes were investigated on Nerium oleander and Robinia pseudo acacia in Tehran. Considering the information obtained from the Department of the Environment of Iran, Sorkh Hesar Park as well as South Azadi were selected as two sampling sites representing the unpolluted and polluted area respectively. A number of plant leave samples were collected from both sampling sites simultaneously. The activity of plant enzymes including peroxidase, catalase and ascorbate peroxidase was investigated using spectrophotometric methods. A higher level of peroxidase and catalase enzymes were measured in both plant samples collected from polluted area. However, this higher level was only statistically significant for the activity of peroxidase enzyme in Robinia pseudo acacia plants compare of to the control group [p<0.05]. The lower level of ascorbate peroxidase was observed in Nerium oleander plant leaves collected from the contaminated sampling site [p<0.05], but though, the activity of this enzyme in Robinia pseudo acacia did not change significantly. The overall plant injury symptoms found in this study demonstrated that both Nerium oleander and Robinia pseudo acacia have a potential to be considered as effective bioindicators to reflect the environmental air quality in polluted areas