Effects of pyrene on antioxidant systems and lipid peroxidation level in mangrove plants, Bruguiera gymnorrhiza.

The effects of polycyclic aromatic hydrocarbon (PAH) (pyrene) on superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase, peroxidase, malondialdehyde (MDA) and proline were studied in leaves, stems and roots of Bruguiera gymnorrhiza. The results showed that the responses of enzymatic and non-enzymatic antioxidants varied significantly among the three tissues studied. The activities of antioxidant enzymes in PAH-treated stems and roots fluctuated in different stress levels compared to the controls, while the antioxidant enzymes such as SOD, APX in leaves increased when stressed by PAH with a significant positive relation between PAH and leaf SOD or APX activity. Low PAH treatments could also stimulate proline in leaves and stems. MDA content was obviously accumulated in stems and roots under PAH stress while decreased in leaves, indicating that the increased antioxidant enzymes in leaves may partly alleviate lipid peroxidation. For pollution monitoring purpose, SOD and APX in leaves may be potential biomarkers of PAH pollution in intertidal estuaries.