Antioxidant effects of propolis on carp Cyprinus carpio exposed to arsenic: biochemical and histopathologic findings

Propolis, a resinous material produced by worker bees from the leaf buds and exu- dates of plants, is reported to possess various therapeutic properties. The aim of this study was to investigate the effects of propolis on biochemical parameters and histopathologic findings in carp Cyprinus carpio L. exposed to arsenic. A sublethal concentration of arsenic (0.01 mg l �1 ) and/or 10 mg l �1 propolis were administered to fish for 1 wk. Catalase (CAT) activities and malondialde- hyde (MDA) levels were determined in liver, gill and muscle tissues in control, arsenic only, propolis only and arsenic+propolis treatment groups. Results showed that CAT activity decreased in the arsenic group compared to the control and propolis groups. CAT activity in the arsenic+ propolis group was significantly higher compared to the arsenic group. MDA levels in fish exposed to 0.01 mg l �1 arsenic significantly increased compared to the control group. However, MDA levels in the arsenic+propolis group were significantly lower compared to the arsenic group. Histopathological changes in the liver, gill and muscle tissues of carp were examined by light microscopy: various changes were observed in all tissues of fish in the arsenic group. Propolis showed important antioxidant effects against arsenic toxicity in all fish tissues.