Antialgal Effect And Mechanism Of The Root Of Eichhornia Crassipes To HABs Algae

Object: The removal effects of the extracts from Eichhornia crassipes roots on HABs algae, Alexandrium tamarense and Prorocentrum donghaiense Lu, were observed to screen newly and efficient algaecides in controlling HABs. The chemical basis and mechanism of the antialgal effect were discussed.Method: The effects of dry powder and extracts from acetone or ethyl acetate of Eichhornia crassipes roots in different concentrations on the growth of A. tamarens or P. donghaiense Lu were observed. The components in acetone extract from Eichhornia crassipes were analysed by GC-MS and HPLC. The inhibitory activities of chemicals in the acetone extract from Eichhornia crassipes were determinated. On the basis of comparison in removal efficiency and toxicity of the chemicals assayed, the effect of N-phenyl-2-naphthylamine, the best candidate to control HABs, onprotein, MDA and SOD of A. tamarense was studied.Result: When the concentration of E. crassipes roots dry powder was lower than 1.0g/L, the growth of A. tamarense and P. donghaiense Lu was stimulated, whereas the growth was inhibited completely when the concentration were higher than 1.5g/L. The growth of A. tamarense and P. donghaiense Lu was above 50% inhibited by 0.038g/L and 0.019g/L extract of acetone E.crassipes roots, respectively. For extract of ethyl acetate, at the actual concentrations of 0.022g/L and 0.015g/L, inhibitory rate of A. tamarense and P. donghaiense Lu was up to 50%. 5mg/L of N-phenyl-2-naphthylamine was showed to have 50% inhibitory rate to A. tamarense after 3 days, and 1mg/L was above 60% inhibition to P. donghaiense Lu after 6 days. 70 μL/L of linoleic acid apperared 40% inhibition to A. tamarense while 50 μL/L had 82% inhibition to P. donghaiense Lu. 70μL/L of Pelargonic acid had highest inhibition rate at the 3rd day with some increase in cell density. GC-MS and HPLC showed that in addition to N-phenyl-2-naphthylamine and linoleic acid, long chain fatty acids such as hexadecanoic acid, 9-hexadecenoic acid existed in the extract in relatively high content. N-phenyl-2-naphthylamine not only affected the protein,MDA and SOD of A. tamarense, but also damaged cell structure.Conclusion: E. crassipes root could inhibit remarkably HABs alage. N-phenyl-2-naphthylamine and linoleic acid might play an important role in the inhibition. The allelochemicals in E. crassipes might damage the algae cell structure through free radical reaction. The allelochemicals from E.crassipes roots such as N-phenyl-2-naphthylamine might be a potential candidate in HABs control.