Characterization of Benzoyl Saxitoxin Analogs from the Toxigenic Marine Dinoflagellate Gymnodinium catenatum by Hydrophilic Interaction Liquid Ion-Chromatography-Tandem Mass Spectrometry

Abstract

The chain-forming marine dinoflagellate Gymnodinium catenatum Graham has a remarkable capacity to produce a wide array of neurotoxic alkaloids associated with Paralytic Shellfish Poisoning (PSP). More than a decade ago, a completely new group of benzoyl saxitoxin analogs produced exclusively by this species was discovered, but the exact structural assignments and diversity among global population has remained elusive and unconfirmed in most cases. In the current study, fifteen among eighteen hypothetical benzoyl analogs were partially purified and identified from cultured isolates of G. catenatum from the Pacific coast of Mexico. Combined serial application of flash chromatography, preparative liquid chromatography and tandem mass spectrometry (LC-MS/MS) in multiple steps yielded a richness of benzoyl analogs that has not been reported nor confirmed before. Two sub-fractions were analyzed by 1 H-NMR; results from one fraction showed a probable AMX pattern for three protons, consistent with the presence of a 3,4-dihydroxylated benzoyl ring. These findings could be interpreted to correct the 2,4-dihydroxylated structure previously proposed for the GCa benzoyl analog series. The revised and enhanced structural information on proposed benzoyl derivatives is necessary to provide further insights into biogeographical diversity of these potentially potent toxins produced by marine dinoflagellates and their role in seafood safety.

Accumulation and Elimination Dynamics of the Hydroxybenzoate Saxitoxin Analogues in Mussels Mytilus galloprovincialis Exposed to the Toxic Marine Dinoflagellate Gymnodinium catenatum

“…In addition to classic PST, hydroxybenzoyl derivatives were detected, representing a significant part of the toxin profile of G. catenatum. GC1 to GC6 were here identified as previously found [ 6 ] in a different G. catenatum strain, isolated from the Portuguese coast, but none of the di-hydroxybenzoyl or sulfobenzoyl GC analogues indicated [ 4 , 7 ] were observed.…”

“…Indeed, Gymnodinium catenatum has been shown to produce a wide array of PST. In subsequent years, several other hydroxybenzoate analogues have been reported and designated as p -hydroxybenzoyl, di-hydroxybenzoyl, and sulfo-benzoyl derivatives [ 4 , 5 , 6 , 7 ]. The toxicity of GC toxins is still poorly known.…”

Computational Model of Adsorption for Hydroxybenzoate Saxitoxin Derivatives (GCs) on Graphene Surface

“…Qualitative analysis of the kinetics of GTX1&4 and NEO hydrolysis signals shows that dcGTX1&4 and dcNEO are labile to conventional hydrolysis conditions, and are therefore transient intermediates, although final degradation products were not detected by the MS/MS used in this study of Laboratorio CIFGA. Among the more than 50 known analogues, the group with an aromatic substituent at position R4 is called GC analogues, which comprises three sub-groups according to aromatic substituent [4]:…”

“…p-hydroxybenzoate: GC1 to GC6 (Figure 3) -o,m-dihydroxybenzoate: GC1a to GC6a -p-sulfobenzoate: GC1b to GC1b Among the more than 50 known analogues, the group with an aromatic substituent at position R4 is called GC analogues, which comprises three sub-groups according to aromatic substituent [4]:…”