Extraction and purification of the zwitterions cylindrospermopsin and deoxycylindrospermopsin from Cylindrospermopsis raciborskii

The hepatotoxin cylindrospermopsin (CYN) has been isolated from the cyanoba cterium Cylindrospermopsis raciborskii (C. raci.). Efforts to study this to xin have been hampered by the time-consuming requirement to extract it from cultures of the organism. It is usually extracted from lyophilized cells c ollected from a laboratory culture. Our preliminary work suggested far more of the toxin is available in solution in the culture media than in the cel ls collected. We have therefore investigated the use of commercially availa ble solid phase extraction sorbents to extract CYN from culture media in wh ich C. raci. has been grown. A range of reverse phase and ion-exchange sorb ents were tested across a range of pHs for their ability to retain CYN with out success. Subsequently, graphitized carbon cartridges were found to reta in CYN strongly. Elution with 5% formic acid in methanol allowed the CYN to be regained for final purification by HPLC. Deoxy-CYN, an analog of CYN ca n also be extracted using this procedure. (C) 2001 John Wiley & Sons, Inc.