Ζ). Complex Polycyclic Compounds
145
irregularly for no apparent reason and generally last for a few weeks. Early
human symptoms that may appear within thirty minutes after eating toxic
shellfish consist of numbness of lips and fingertips ; this is followed by paralysis
and death, generally within 1-12 hours depending on the dose. It is estimated
that the lethal dose in man is about 0.3 mg of toxin.
It was only in 1937 that a group of researchers in California (Sommer and
Meyer, 1937; Sommer et al, 1937) connected the presence of a dinoflagellate
Gonyaulax catenella in California waters to the outbreak of mussel poisoning.
It was established that a G. catenella count of 100 to 200 cells per milliliter
of water rendered the mussels too toxic for human consumption. However, a
visible "red tide" is achieved only when the organism reaches or surpasses
a count of 20,000 cells per milliliter. The threshold count of about 200 cells
per milliliter is detectable only by microscopic examination. Obviously then,
paralytic shellfish poisoning continues to be a public health threat and the
popularly held danger signal of the "red tide" misses being an alarm beacon
by two orders of magnitude !
Although there existed considerable evidence that the toxin that was
elaborated by the dinoflagellate G. catenella was the same as the toxin that is
accumulated in the dark gland or hepatopancreas of the mussel Mytilus
californianus, identity was only conclusively demonstrated in 1966. Schantz
and co-workers (1966) isolated the toxin from an axenic culture of G. catanella and from the dark gland of M. californianus and proved their identity.
Schantz et al (1966) further showed that the poison is also identical with
saxitoxin, the toxin accumulated and stored in the siphon of the Alaska
butter clam Saxidomus giganteus, and which had been characterized and
named by Schuett and Rapoport (1962). In contrast to the mussel, which
becomes safe for human consumption after a few weeks, the Alaska butter
clam retains the toxin in its siphon for many months. Furthermore no direct
link has been established between the toxicity of S. giganteus and another toxic
organism. Schantz and Magnusson (1964) did locate Gonyaulax in Alaskan
waters, but only rarely and in small numbers.
No fully conclusive proof of the identity of saxitoxin with the paralytic
shellfish poison produced by the Bay of Fundy scallop Pecten grandis has
yet been published (Schantz, 1960), but it has been shown that toxicity of
Bay of Fundy shellfish is associated with plankton blooms, particularly of
G. tamarensis (Needier, 1949).
Only a few papers have been published on the chemistry of saxitoxin,
which with an intravenous lethal dose of 3-4/xg/kg (Murtha, 1960) is one
of the most toxic nonprotein substances known. Isolation and purification
were described by Schantz et al (1957) and Mold et al (1957), who established
the molecular formula of saxitoxin dihydrochloride as C 1 0 H 1 7 N 7 O 4 -2 HCl
and demonstrated its homogeneity although neither saxitoxin nor its salt
145
irregularly for no apparent reason and generally last for a few weeks. Early
human symptoms that may appear within thirty minutes after eating toxic
shellfish consist of numbness of lips and fingertips ; this is followed by paralysis
and death, generally within 1-12 hours depending on the dose. It is estimated
that the lethal dose in man is about 0.3 mg of toxin.
It was only in 1937 that a group of researchers in California (Sommer and
Meyer, 1937; Sommer et al, 1937) connected the presence of a dinoflagellate
Gonyaulax catenella in California waters to the outbreak of mussel poisoning.
It was established that a G. catenella count of 100 to 200 cells per milliliter
of water rendered the mussels too toxic for human consumption. However, a
visible "red tide" is achieved only when the organism reaches or surpasses
a count of 20,000 cells per milliliter. The threshold count of about 200 cells
per milliliter is detectable only by microscopic examination. Obviously then,
paralytic shellfish poisoning continues to be a public health threat and the
popularly held danger signal of the "red tide" misses being an alarm beacon
by two orders of magnitude !
Although there existed considerable evidence that the toxin that was
elaborated by the dinoflagellate G. catenella was the same as the toxin that is
accumulated in the dark gland or hepatopancreas of the mussel Mytilus
californianus, identity was only conclusively demonstrated in 1966. Schantz
and co-workers (1966) isolated the toxin from an axenic culture of G. catanella and from the dark gland of M. californianus and proved their identity.
Schantz et al (1966) further showed that the poison is also identical with
saxitoxin, the toxin accumulated and stored in the siphon of the Alaska
butter clam Saxidomus giganteus, and which had been characterized and
named by Schuett and Rapoport (1962). In contrast to the mussel, which
becomes safe for human consumption after a few weeks, the Alaska butter
clam retains the toxin in its siphon for many months. Furthermore no direct
link has been established between the toxicity of S. giganteus and another toxic
organism. Schantz and Magnusson (1964) did locate Gonyaulax in Alaskan
waters, but only rarely and in small numbers.
No fully conclusive proof of the identity of saxitoxin with the paralytic
shellfish poison produced by the Bay of Fundy scallop Pecten grandis has
yet been published (Schantz, 1960), but it has been shown that toxicity of
Bay of Fundy shellfish is associated with plankton blooms, particularly of
G. tamarensis (Needier, 1949).
Only a few papers have been published on the chemistry of saxitoxin,
which with an intravenous lethal dose of 3-4/xg/kg (Murtha, 1960) is one
of the most toxic nonprotein substances known. Isolation and purification
were described by Schantz et al (1957) and Mold et al (1957), who established
the molecular formula of saxitoxin dihydrochloride as C 1 0 H 1 7 N 7 O 4 -2 HCl
and demonstrated its homogeneity although neither saxitoxin nor its salt