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The chemical nature of the toxic secretions of the boxfish (Ostracion lentiginosus Schneider)

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Title:The chemical nature of the toxic secretions of the boxfish (Ostracion lentiginosus Schneider)
Authors:Boylan, David Bradley
Ostracion lentiginosus
Date Issued:1966
Abstract:An interesting metabolite may have come to light when it was noted that the secretions collected from a disturbed Hawaiian boxfish. (Ostracion lentiginosus Schneider) were extremely toxic to other reef fish. The toxin has been named pahutoxin since pahu is the Hawaiian name for the boxfish. A simple bioassay developed by Thomson using brackish water mo11ies as test fish proved useful in devising an efficient isolation scheme. Initial extraction of the crude toxic secretions with butanol was followed by chromatography of the butanol residue on silicic acid and picric acid-coated anion exchange resin. The resulting product crystallized from acetone and exhibited an optical rotation [α] 200D + 3.08° (methanol) and a melting point of 750°. Nuclear magnetic resonance and infrared spectra demonstrated the presence of a trimethyl quaternary nitrogen, a large aliphatic portion, and the presence of one or more ester functions. Hydrolytic degradation studies provided several key products that allowed the total structure of pahutoxin to be postulated as choline 3-acetoxypalmitate (I). Proof of the structure rested in the synthesis of racemic pahutoxin by a modified Reformatsky reaction. The product, 3-hydroxypalmitic acid, was acetylated with acetyl chloride and esterified with choline to give a compound which was spectrally identical with natural pahutoxin. By the same synthetic procedure the 3-acetoxy esters of pelargonic (C9), lauric (C12), myristic (C14), and palmitic (C16) acids were synthesized and their. biological activities were compared with the activities of natural pahutoxin. Decrease in aliphatic chain length, with all other structural features unchanged, was accompanied by a marked decrease in toxicity and hemolytic ability. The parallelism of these two activities suggested that either hemolysis is the cause of toxicity to fish or it is closely related to it. Intravenous injection of pahutoxin into rats caused symptoms paralleling those exhibited by the mushroom poison muscarine. Pahutoxin is the only choline ester of a fatty acid which has been detected in fish secretions. Evidence of an exotoxin, similar to pahutoxin, has been detected in the cowfish Lactoria fornasini (Linnaeus), but not in the closely related puffer fish Sphaeroides rubripes (Temminick and Schlegel).
Thesis (Ph. D.)--University of Hawaii, 1966.
Bibliography: leaves [77]-79.
ix, 79 l illus., tables
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Appears in Collections: Ph.D. - Chemistry

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