Three minor microcystins have been isolated from a Planktothrix rubescens strain.Their structures have been elucidated by one-and two-dimensional NMR spectroscopy and high-resolution tandem mass spectrometry as the co...Three minor microcystins have been isolated from a Planktothrix rubescens strain.Their structures have been elucidated by one-and two-dimensional NMR spectroscopy and high-resolution tandem mass spectrometry as the compounds[Asp^(3),(E)-Dhb^(7)]MC-LY(1),[Asp^(3),(E)-Dhb^(7)]MC-HtyW(2),and[Asp^(3),(E)-Dhb^(7)]MC-LW(3).The amino acids found at the variable positions 2 and 4 of the microcystin core structure are in accordance with the predicted amino acid substrate activation selectivities of the non-ribosomal peptide synthetases McyA and McyB described earlier for this strain.All structural microcystin variants produced by this strain were shown to inhibit protein phosphatase 1 in the nanomolar range.展开更多
Microcystins （MCs） produced by cyanobacteria are strong hepatotoxins and classified as possible carcinogens. MCs pose a considerable threat to human health through tainted drinking and surface waters. Herein filtrat...Microcystins （MCs） produced by cyanobacteria are strong hepatotoxins and classified as possible carcinogens. MCs pose a considerable threat to human health through tainted drinking and surface waters. Herein filtrated water from a waterworks in Harbin, China, was spiked with microcysfin-LR （MC-LR） extracted from a toxic scum of microcystis aeruginosa, and the spiked sample waters were treated using UV irradiation with consequent ozonation process （UV/O3）, compared with ozonation at a dose range commonly applied in water treatment plants, UV irradiation at 254 nm and UV irradiation combined with ozonation （UV＋O3）, respectively. The remaining of toxins were analyzed using high-performance liquid chromatography and also determined using a protein phosphatase type 2A inhibition assay, which was utilized to evaluate the reduction in toxicity. Results indicated that in comparison to other three processes （O3, UV, and UV＋O3）, UV/O3 process could effectively decrease both the concentration and toxicity of MC-LR at 100 μg/L level after 5 min UV irradiation with consequent 5 min ozonation at 0.2 mg/L （below 1 μg/L ）, while 0.5 mg/L ozone dose was required for the level below 0.1 μg/L. The addition of an UV treatment step to the existing treatment train may induce significant transformation of micropollutants and breaks down the natural organic matters into moieties unfavorable for ozone decomposition, stabilizing the ozone residual. These findings suggested that sequential use of UV and ozone may be a suitable method for the removal of these potentially hazardous microcystins from drinking water.展开更多
基金supported by the German Federal Ministry of Economics and Technology(KF2766301SB0)the Leibniz-Institut fur Molekulare Phamakologie(FMP),the Austrian Science Fund(P24070)the Austrian Climate Research Program(ACRP)project RADICAL(Risk Analysis of Direct and Indirect Climate effects on deep Austrian Lake Ecosystems).
文摘Three minor microcystins have been isolated from a Planktothrix rubescens strain.Their structures have been elucidated by one-and two-dimensional NMR spectroscopy and high-resolution tandem mass spectrometry as the compounds[Asp^(3),(E)-Dhb^(7)]MC-LY(1),[Asp^(3),(E)-Dhb^(7)]MC-HtyW(2),and[Asp^(3),(E)-Dhb^(7)]MC-LW(3).The amino acids found at the variable positions 2 and 4 of the microcystin core structure are in accordance with the predicted amino acid substrate activation selectivities of the non-ribosomal peptide synthetases McyA and McyB described earlier for this strain.All structural microcystin variants produced by this strain were shown to inhibit protein phosphatase 1 in the nanomolar range.
基金supported by the National High Technology Research and Development Program(863) of China(No. 2007AA06Z339)the 11th Five-year Plan of National Science and Technology Infrastructure Program of China(No. 2006BAJ08B02)
文摘Microcystins （MCs） produced by cyanobacteria are strong hepatotoxins and classified as possible carcinogens. MCs pose a considerable threat to human health through tainted drinking and surface waters. Herein filtrated water from a waterworks in Harbin, China, was spiked with microcysfin-LR （MC-LR） extracted from a toxic scum of microcystis aeruginosa, and the spiked sample waters were treated using UV irradiation with consequent ozonation process （UV/O3）, compared with ozonation at a dose range commonly applied in water treatment plants, UV irradiation at 254 nm and UV irradiation combined with ozonation （UV＋O3）, respectively. The remaining of toxins were analyzed using high-performance liquid chromatography and also determined using a protein phosphatase type 2A inhibition assay, which was utilized to evaluate the reduction in toxicity. Results indicated that in comparison to other three processes （O3, UV, and UV＋O3）, UV/O3 process could effectively decrease both the concentration and toxicity of MC-LR at 100 μg/L level after 5 min UV irradiation with consequent 5 min ozonation at 0.2 mg/L （below 1 μg/L ）, while 0.5 mg/L ozone dose was required for the level below 0.1 μg/L. The addition of an UV treatment step to the existing treatment train may induce significant transformation of micropollutants and breaks down the natural organic matters into moieties unfavorable for ozone decomposition, stabilizing the ozone residual. These findings suggested that sequential use of UV and ozone may be a suitable method for the removal of these potentially hazardous microcystins from drinking water.
