314
FINDLAY E. RUSSELL
in the poisoning, and the reader should consult his work for a more
thorough review. Banner et al. (1960) have presented some interesting
data on the possible role of algae of the genus Lyngbya as agents in
the poisoning.
More recently, Banner et d. (1963b) have studied the stomach
contents of toxic L. bohur and have found the principal constituent
to be reef fishes, particularly acanthurids. As many of the Acanthuridae on which L. bohar feeds are toxic it was suggested that this
family of fishes may be the chief dietary source of the toxin. Acanthurids, in turn, appear to feed on many kinds of algae. One of the
blue-green algae, Plectonema terebrans (Borinet and Flahautt), was
found growing epiphytically on most of the algae eaten by the common
acanthurids in Christmas Island; this alga has been suspected of
being associated with fish poisoning in the Gilbert Islands. Helfrich
and Banner (1963) have shown that several non-toxic fish fed on a diet
of toxic L. bohar may become toxic.
(a) Chemistry. Regrettably, most of the investigations on the
chemistry and toxicology of ciguatera toxin prior to 1955 contributed
very little to our present knowledge on this poison. Indeed, these studies
sometimes led investigators into rather unfruitful areas. Among other
problems there was considerable confusion about the solubility of the
toxin, and it was not until the works of Hashimoto (1956), Banner and
Boroughs (1958) and McFarren and Bartsch (1959) that it became
apparent that the more lethal portions of the poison could not initially
be extracted with water. This finding helped to clarify some of the
discrepancies previously reported. By the end of 1959, ciguatera
poison was described as being heat stable, stable to drying, soluble
in ether, petroleum ether, chloroform, acetone, methanol and 90%
ethanol, and insoluble in water and dilute acids. It was thought to
be a lipid. It was also described as being dialyzable.
In 1960, Banner et al. reported that a partially purified extract
of the toxin from L. bohar could be obtained by extraction of the
dried tissues of the fish with 95% ethanol, followed by concentration,
dilution with distilled water to an alcoholic solution of approximately
25%, extraction with diethyl ether and evaporation of the ethereal
extract to dryness. In a peanut oil vehicle the extract was found to be
lethal at 200 mg/kg body weight when injected intraperitoneally into
mice. Further tests indicated that Soxhlet extraction with alcohol
was a superior method for separating the toxin. A more lethal fraction
was subsequently obtained by column chromatography using sol vents
of varying polarity.
FINDLAY E. RUSSELL
in the poisoning, and the reader should consult his work for a more
thorough review. Banner et al. (1960) have presented some interesting
data on the possible role of algae of the genus Lyngbya as agents in
the poisoning.
More recently, Banner et d. (1963b) have studied the stomach
contents of toxic L. bohur and have found the principal constituent
to be reef fishes, particularly acanthurids. As many of the Acanthuridae on which L. bohar feeds are toxic it was suggested that this
family of fishes may be the chief dietary source of the toxin. Acanthurids, in turn, appear to feed on many kinds of algae. One of the
blue-green algae, Plectonema terebrans (Borinet and Flahautt), was
found growing epiphytically on most of the algae eaten by the common
acanthurids in Christmas Island; this alga has been suspected of
being associated with fish poisoning in the Gilbert Islands. Helfrich
and Banner (1963) have shown that several non-toxic fish fed on a diet
of toxic L. bohar may become toxic.
(a) Chemistry. Regrettably, most of the investigations on the
chemistry and toxicology of ciguatera toxin prior to 1955 contributed
very little to our present knowledge on this poison. Indeed, these studies
sometimes led investigators into rather unfruitful areas. Among other
problems there was considerable confusion about the solubility of the
toxin, and it was not until the works of Hashimoto (1956), Banner and
Boroughs (1958) and McFarren and Bartsch (1959) that it became
apparent that the more lethal portions of the poison could not initially
be extracted with water. This finding helped to clarify some of the
discrepancies previously reported. By the end of 1959, ciguatera
poison was described as being heat stable, stable to drying, soluble
in ether, petroleum ether, chloroform, acetone, methanol and 90%
ethanol, and insoluble in water and dilute acids. It was thought to
be a lipid. It was also described as being dialyzable.
In 1960, Banner et al. reported that a partially purified extract
of the toxin from L. bohar could be obtained by extraction of the
dried tissues of the fish with 95% ethanol, followed by concentration,
dilution with distilled water to an alcoholic solution of approximately
25%, extraction with diethyl ether and evaporation of the ethereal
extract to dryness. In a peanut oil vehicle the extract was found to be
lethal at 200 mg/kg body weight when injected intraperitoneally into
mice. Further tests indicated that Soxhlet extraction with alcohol
was a superior method for separating the toxin. A more lethal fraction
was subsequently obtained by column chromatography using sol vents
of varying polarity.