ABSTRACT
Azaspiracids (AZAs) and yessotoxins (YTXs) are natural compounds with different chemical structures, origins, toxicological relevance in humans, and as yet undetermined molecular mechanism of action. The structure of AZAs is characterized by the presence of an acidic function, a cyclic amino group, and a spiro ring sytem (Rossini and Hess 2010). The origin of these compounds has remained uncertain for several years, and it is now recognized that AZAs are produced by microalgae of the genus Azadinium (Krock et al. 2009, 2012). The toxicological relevance of AZAs is at the basis of their discovery, as cases of human poisoning in the Netherlands in 1995 (McMahon and Silke 1996, Satake et al. 1998), due to eating of mussels harvested in Killary Harbour (Ireland), attracted the attention of chemists and toxicologists onto agents originally defi ned as “Killary Harbour Toxin fraction 3, KT-3” (Yasumoto and Satake 1998). YTXs consist of polyether lipophilic compounds, possessing a negatively charged head, due to the presence of two sulfate groups, and a hydrophobic tail (for a review, see Suzuki 2013). They are produced by microalgae of the genera Protoceratium, Lyngulodinium and Gonyaulax (Rhodes and Wood 2014), and were originally
Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Via G. Campi 287, I-41125 Modena, Italy. aEmail: gianpaolo.rossini@unimore.it bEmail: gianluca.sala@unimore.it *Corresponding author
isolated from contaminated scallops (Patinopecten yessoensis), providing the name of this group of compounds (Murata et al. 1987). Animal studies have shown that YTXs are toxic when administered by i.p. injection in the mouse, with LD50 in the 80-830 µg/kg b.w. range (EFSA 2008b). Based on existing studies, however, administration of YTXs by gavage does not appear to be accompanied by severe acute effects in mice (EFSA 2008b). AZAs, in turn, are very toxic by both i.p. injection and oral route (EFSA 2008a). The toxicity of AZAs and YTXs by the oral route in animal models, therefore, are quite different (Table 1), and the reasons for this remain unclear.
