Two new skeletal analogues of saxitoxin found in the scallop, Patinopecten yessoensis, as possible metabolites of paralytic shellfish toxins

The scallop, Patinopecten yessoensis, was screened for new saxitoxin analogues to study the metabolism of paralytic shellfish toxins (PSTs), and this resulted in discovery two analogues: M5-hemiaminal (HA) M6-HA. M5-HA isolated its structure determined by using NMR spectroscopy. It contains hydrogen at C-4 with opposite stereochemistry that saxitoxin, a hemiaminal formed between 9-NH2 hydrated ketone C-12 ?-orientation. This is first reported structural feature natural analogue, whereas same ring system has previously been synthetic FD-saxitoxin. Acid hydrolysis carbamoyl N-sulfate produced M6-HA which also identified P. yessoensis LC-MSMS. not synthetically from M1 (11-hydroxy gonyautoxin-5) M3 (11,11-dihydroxy through incubation aqueous buffers. Furthermore, PSTs hepatopancreas cultured bay located northeastern Japan, were chronologically analyzed 2018. highest concentrations M1/M3/M5-HA observed weeks after C-toxins had reached their concentrations, provides evidence are metabolites C-toxins. voltage-gated sodium channel blockage activity detected concentration 140 nM Neuro-2A veratridine/ouabain assay.