ERETIC2 (Electronic Reference To access In vivo Concentrations 2) based on PULCON (Pulse Length–based Concentration determination) methodology is a quantitative NMR (qNMR) using an external standard. The performance of the PULCON method was assessed using maleic acid (MA). Quantification of the diarrhetic shellfish toxin and okadaic acid by PULCON was successfully consistent with that obtained by a conventional internal standard method, demonstrating that the PULCON method is useful for the quantification of invaluable marine toxins without any contaminations by an internal standard.

Cyanobacteria have been shown to produce a number of bioactive compounds, including toxins. Some bioactive compounds obtained from a marine cyanobacterium Moorea producens (formerly Lyngbya majuscula) have been recognized as drug leads; one of these compounds is aplysiatoxin. We have isolated various aplysiatoxin derivatives from a M. producens sample obtained from the Okinawan coastal area. The frozen sample was extracted with organic solvents. The ethyl acetate layer was obtained from the crude extracts via liquid–liquid partitioning, then separated by HPLC using a reversed-phase column. Finally, 1.1 mg of the compound was isolated. The chemical structure of the isolated compound was elucidated with spectroscopic methods, using HR-MS and 1D and 2D NMR techniques, and was revealed to be oscillatoxin I, a new member of the aplysiatoxin family. Oscillatoxin I showed cytotoxicity against the L1210 mouse lymphoma cell line and diatom growth-inhibition activity against the marine diatom Nitzschia amabilis.

Japanese scallops, Patinopecten yessoensis, were fed with the toxic dinoflagellate Dinophysis fortii to elucidate the relative magnitude of assimilation, accumulation, and metabolism of diarrhetic shellfish toxins (DSTs) and pectenotoxins (PTXs). Three individual scallops were separately exposed to cultured D. fortii for four days. The average cell number of D. fortii assimilated by each individual scallop was 7.7 × 10⁵. Dinophysistoxin-1 (DTX1), pectenotoxin-2 (PTX2) and their metabolites were analyzed by liquid chromatography tandem mass spectrometry (LC/MS/MS) and the toxin content in individual tissues (digestive gland, adductor muscle, gill, gonad, mantle, and the others), feces and the seawater medium were quantified. Toxins were almost exclusively accumulated in the digestive gland with only low levels being detected in the gills, mantles, gonads, and adductor muscles. DTX1 and PTX2 were the dominant toxins in the D. fortii cells fed to the scallops, whereas the dominant toxins detected in the digestive gland of scallops were PTX6 and esterified acyl-O-DTX1 (DTX3). In other tissues PTX2 was the dominant toxin observed. The ratio of accumulated to assimilated toxins was 21%–39% and 7%–23% for PTXs and DTXs respectively. Approximately 54%–75% of PTX2 and 52%–70% of DTX1 assimilated by the scallops was directly excreted into the seawater mainly without metabolic transformation.

A new aplysiatoxin derivative, neo-aplysiatoxin A (1), along with seven known compounds, neo-debromoaplysiatoxin A (2), dolastatin 3 (3), lyngbic acid (4), malyngamide M (5), hermitamide A (6), (−)-loliolide (7), and (+)-epiloliolide (8), was isolated from the Okinawan cyanobacterium Moorea producens. Their structures were elucidated on the basis of spectroscopic data, including high-resolution mass spectrometry and nuclear magnetic resonance. The compounds were evaluated for cytotoxic and diatom growth inhibition activities.