Inhibitory effects and oxidative damages in Cladophora sp. (Cladophoraceae) exposed to berberine

Cladophora members are present in seawater and freshwater ecosystems worldwide. Their growth poses a serious threat to water environment, fisheries, production and living. In order to explore safe and ecological treatment methods, the inhibitory effects and oxidative damages (48 and 96 h) in Cladophora sp. (Cladophoraceae) exposed to 0-0.30 g L-1 berberine were investigated. Results showed that the LC 50 of berberine to Cladophora was 0.147 g L-1 and 0.063 g L-1 at 48 h and 96 h, respectively. Malondialdehyde and total protein contents first increased and then decreased sharply with increasing exposure concentrations of berberine. The Cladophora cells accelerated protein synthesis when their cell membranes were subjected to oxidative damage. Superoxide dis-mutase activity was down-regulated slightly after exposure to low berberine concentration (0.05 g L-1) and strongly when the Cladophora cells suffered from great oxidative damage. Total antioxidant capacity (T-AOC) first decreased sharply and then increased with increasing exposure concentrations of berberine. The decrease in T-AOC indicated the enzymatic antioxidants were continuously inhibited with increasing exposure concentra-tions of berberine. The increase in T-AOC indicated the secretion of non-enzymatic antioxidants was continu-ously strengthened with increasing exposure concentrations of berberine. Cladophora DNA also underwent oxidative damage due to berberine. Low concentrations of berberine activated its repair mechanisms, but high concentrations could cause irreparable damage. Therefore, these results suggested that berberine could inhibit the growth of Cladophora by oxidative damage, and Cladophora responded physiologically to this stress accordingly.