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  7. BBB - Saxitoxin Structure
  1. Bad Bug Book (Second Edition)

BBB - Saxitoxin Structure

Bad Bug Book:
Foodborne Pathogenic Microorganisms and Natural Toxins Handbook
Saxitoxin

Bad Bug Book 2nd Edition: Shellfish toxins (PSP, DSP, NSP, ASP, AZP)

Molecular structure of saxitoxin groups: carbamates (most potent), decarbamoyl toxins (intermediate in toxicity; usually present in shellfish but not toxigenic algae), N-sulfocarbamoyl toxins (less potent), and hydroxybenzoate toxins (more recently recognized group of PSP toxins, shown to be specific to the dinoflagellate Gymnodinium catenatum). Toxins in the saxitoxin family may be produced by a range of dinoflagellates, including species in the genera Alexandrium, Gymnodinium, and Pyrodinium. There are also reports of STXs being produced by certain freshwater and brackish cyanobacteria as well as calcareous red macro algae. The traditional route of exposure is accumulation in filter-feeding shellfish.

Chemical Structure of Saxitoxin and derivatives (final, transparent)

R1 R2 R3 Carbamate
Toxins		 Decarbamoyl
Toxins		 N-sulfocarbamoyl
Toxins		 Hydroxybenzoate
Toxins
H H H STX dc-STX B1 GC3
OH H H NEO dc-NEO B2  
OH H OSO3- GTX 1 dc-GTX 1 C3  
H H OSO3- GTX 2 dc-GTX 2 C1 GC1
H OSO3- H GTX 3 dc-GTX 3 C2 GC2
OH OSO3- H GTX 4 dc-GTX 4 C4  
      R4:
Saxitoxin structure: carbamate group (transparent)		 R4:

Saxitoxin structure: OH group (decarbamoyl) (transparent)		 R4:
Saxitoxin structure: group: N-sulfocabamoyl group (transparent)		 R4:
Saxitoxin structure: group: hydroxybenzoate group (transparent)