The effect of a sublethal concentration of Solanum nigrum on some antioxidants in Biomphalaria arabica.

Schistosomisis is endemic in many rural areas of developing countries. The life cycle of schistosomes is complex with two hosts, an intermediate snail host and a definitive human host. Biomphalaria arabica is the intermediate host for Schistosoma mansoni in Saudi Arabia. One method of controlling the disease is to break the life cycle at the intermediate host snail stage using molluscicides. Snails kill schistosomes by a mechanism involving production of reactive oxygen species. In this study malondialdehyde (MDA), and the antioxidants glutathione (GSH), catalase (CAT) and glutathione peroxidase (GP(x)) were determined in tissue homogenates of B. arabica treated with sublethal concentration (LC25) of the plant molluscicide Solanum nigrum. MDA, GSH and CAT were significantly increased in molluscicide-treated snails compared to controls (p < 0.000). GP(x) was decreased in treated snails. It therefore appears that a sublethal concentration of S. nigrum increases both ability of snail tissue to generate cytotoxic ROS and antioxidants for protection of the tissue against the cytotoxicity. The increase in the level of ROS would decrease snail- schistosome compatibility.