| In recent years, water environmental pollution and eutrophication in rivers, lakes andaquaculture ponds lead to the breakdown of harmful algae, and cause a direct threat topeople’s daily lives and fishery production, inducing great social and economic problems. Toexplore effective, economic and no secondary pollution control blooms method become a hotresearch topic. Using plant to inhibit harmful algal growth is economic efficient andenvironmentally friendly. Isolating the effective compounds from plant, studying thestructure-activity relationship and synthesying highly active algal inhibiting chemicals besedon the compounds is a new way of developing cyanobacteria control drugs. Based on theextensive screening study, it’s found that the extraction of Salvia miltiorrhiza has strongerinhibitory activity on Microcystis aeruginosa growth. Therefore, this study used S.miltiorrhiza as the plant materials and M. aeruginosa as the testing algae. Underbioassay-guided multi-column chromatography methods, the effective inhibiting compoundswere isolated from S. miltiorrhiza, and the algal inhibiting specificity and algal inhibitingmechanism of the active compounds were further studied. The following results of this studywere obtained:1. The isolation and identication of the active constitutions inhibiting M. aeruginosafrom S. miltiorrhiza. Using ultrasonic method to extract S. miltiorrhiza with five differentsolvents and then to determine the algal inhibiting effects of different extracts, it’s showedthat the ethyl acetate extract of S. miltiorrhiza with the best inhibitory activity on algal growth.The EC50values at the3day and7day on the M. aeruginosa were85.18and76.07mg/L,respectively, lower than other extracts. Select ethyl acetate as the solvent for the extraction ofS. miltiorrhiza. Using the bioassay-guided method and through multi-column chromatographytechnology, two active compounds were obtained from ethyl acetate extraction of S.miltiorrhiza. By spectroscopy identification, compoundⅠ was identified ascryptotanshinoneand compound Ⅱ was identified as neo-przewaquinone A. Algal inhibiting test showed thatneo-przewaquinone A had the higher algal inhibiting activity, with the EC50values on3dayand7day of7.30and4.68mg/L, and it had the development potential for new algicide.2. Study on the hehavior of algal inhibiting activity of S. miltiorrhiza. The algal inhibiting feature test of neo-przewaquinone A showed that it had a lower EC50value of M.aruginosa than Chlorella and Scenedesmus obliquus. On the3rdday, the EC50values ofneo-przewaquinone A on Chlorella and S. obliquus. were27.29and10.96mg/L. On the7thday, the EC50values of neo-przewaquinone A on Chlorella and S. scenedesmu were14.78and10.37mg/L.3. For the potential inhibition mechanisms, neo-przewaquinone A could cause algal cellultrastructure damage, leading to deformation, depression, and even cell lysis.Neo-przewaquinone A could decrease the content of soluble protein, increase the MDAcontent, and inhibit the total antioxidant capacity (T-AOC) and superoxide dismutase (SOD)activity. Furthermore, neo-przewaquinone A could also depress the expression ofphotosynthesis related genes of rbcL psaB and psbD, and influenced the photosynthesisefficiency of algae cells to a certain extent. These results showed a comprehensive evaluationof the algal inhibiting mechanism of neo-przewaquinone A on M. aeruginosa.In conclusion, neo-przewaquinone A, isolated from S. miltiorrhiza, could effectivelyinhibit M. aeruginosa. Further study of the inhibiting mechanism of the active compound onM. aeruginosa showed neo-przewaquinone A could affect algal cell ultrastructure, reduce thecontent of soluble protein, damage cell antioxidant system, and inhibit the expression of algalphotosynthesis related genes. |
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