The first evidence of paralytic shellfish toxins in the freshwater cyanobacterium Cylindrospermopsis raciborskii, isolated from Brazil

The blooms of toxic cyanobacteria (blue-green algae) are causing problems i n many countries. During a screening of toxic freshwater cyanobacteria in B razil, three strains isolated from the State of Sao Paulo were found toxic by the mouse bioassay. They all were identified as Cylindrospermopsis racib orskii by a close morphological examination. Extracts of cultured cells cau sed acute death to mice when injected intraperitoneally after developing ne urotoxic symptoms which resembled to those caused by paralytic shellfish to xins. The analysis of the sample by HPLC-FLD postcolumn derivatization meth od for paralytic shellfish toxins resulted in the detection of several saxi toxin analogs. To avoid being misled by false peaks, the sample was reanaly zed after purification and also under the different postcolumn derivatizing conditions. Finally, the newly developed LC-MS method for paralytic shellf ish toxins was applied to unambiguously identify the toxins. One isolate pr oduced neosaxitoxin predominantly with saxitoxin as a minor component. The other two showed identical toxin profiles containing saxitoxin and gonyauto xins 2/3 isomers in the ratio of 1.9. This is the first evidence of paralytic shellfish toxins in this species an d also the occurrence of the toxin producing cyanobacterium in South Americ an countries. (C) 1999 Published by Elsevier Science Ltd. All rights reserv ed.