Identification of 45-hydroxy-46,47-dinoryessotoxin, 44-oxo-45,46,47-trinoryessotoxin, and 9-methyl-42,43,44,45,46,47,55-heptanor-38-en-41-oxoyessotoxin, and partial characterization of some minor yessotoxins, from Protoceratium reticulatum

Abstract Preparative HPLC purification of a side-fraction obtained during purification of 44,55-dihydroxyyessotoxin ( 6 ) afforded fractions containing previously unidentified yessotoxin analogues. Careful analysis of these fractions by HPLC-UV, LC–MS 3 , and NMR spectroscopy, revealed the identities of some of these analogues as 45-hydroxy-46,47-dinoryessotoxin ( 1 ), 44-oxo-45,46,47-trinoryessotoxin ( 2 ) and 9-methyl-42,43,44,45,46,47,55-heptanor-38-en-41-oxoyessotoxin ( 5 ). Numerous other analogues were present but could only be characterized by HPLC-UV and LC–MS 3 due to their low abundance. The HPLC-UV and LC–MS 3 data confirm the presence of large numbers of yessotoxin analogues, some of which may be oxidative degradation products, in extracts of Protoceratium reticulatum. Compound- 1 is the first 46,47-dinoryessotoxin to be identified.