Three Novel Hydroxybenzoate Saxitoxin Analogues Isolated from the Dinoflagellate Gymnodinium catenatum

Abstract

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

“…Sub-fractionation in the initial preparative chromatography yielded putative GC3 toxin (m/z 377>257) in sub-fraction F3.3. Refractionation was successful in obtaining this GC3 toxin with higher purity, but given that the GC3 structure has been previously confirmed by 1 H-NMR [16] this component was not subjected to further confirmation in our study. The two low abundant peaks at transition m/z 393>273 are consistent with the molecular masses of GC6 and GC3a.…”

“…Further investigations revealed that these compounds, named GC1-3 toxins, were indeed new analogs. Extracts containing these analogs were purified for the first time by hydrophilic interaction liquid ion-chromatography (HILIC), and their structures were characterized by mass spectrometry (MS) and nuclear magnetic resonance (NMR) [16]. According to these authors, the GC3 analog is the para-hydroxybenzoyl derivative of dcSTX; GC1 and GC2 are C-11 sulfated variants of GC3 that form an enantiomeric pair depending on the stereochemical position of the sulfate group.…”

“…Despite the fact that these approaches are far from conclusive, they present the possibility that these toxins are relatively toxic in situ. [dcGTXs], and N-sulfocarbamoyl B and C toxins, versus so-called "hydrophobic" (e.g., benzoyl or GC) analogs [16,[19][20][21][22] (Figure 1). Identification of benzoyl analogs has been hampered mainly by the lack of analytical standards [20,21,23], but probable structures for some analogs have been proposed based upon mass spectrometric analysis [20].…”

Developmental Biology of Neoplastic Growth

“…The uppermost molecule is saxitoxin itself with the two analogues shown below having had their carbamoyl chain modified. The leftmost analogue is a hydroxybenzoate saxitoxin (Negri et al 2003) while the carbamoyl chain has been completely removed in the right-hand analogue, decarbamoylSTX (Koehn et al 1981). In all cases, the 1,2,3 guanidinium group is pointing upwards and the elements are colored as in Fig.…”

“…The discovery of new STX analogues has accelerated recently partly due to the realization that standard analytical techniques and sample preparation eliminated them from many extracts (Negri et al 2003(Negri et al , 2007. These toxins are potent Na channel binding toxins (Llewellyn et al 2004).…”