Stability studies on the cyanobacterial nicotinic alkaloid anatoxin-A.
Anatoxin-a (ANTX-a) is a potent nicotinic cholinergic bicyclic secondary amine produced by some toxigenic strains of Anabaena spp. cyanobacteria (LD50 = 0.20-0.25 mg/kg i.p., mouse). Studies were undertaken to examine the effects of sunlight, pH, oxygen, and copper and iron, known catalysts of nitrogen oxidation, on the stability of ANTX-a. Photolysis of this extremely potent toxin was demonstrated under conditions resembling those which occur naturally. First-order decay kinetics of ANTX-a in sunlight was both pH and light intensity dependent. In the solutions examined, which represented expected biological conditions, the half-life of ANTX-a was on the order of 1-2 hr. This compares to half-lives on the order of several days in the absence of sunlight, even in the presence of metal ions. Mouse bioassays indicate that the breakdown products of ANTX-a, by both mechanisms, are inactive. Sunlight photolysis is concluded to be a possible important detoxification route of ANTX-a.
Stevens
D K
DK
Pharmacology/Toxicology Program, College of Pharmacy, Washington State University, Pullman 99164.
Krieger
R I
RI
D000818:Animals; D001427:Bacterial Toxins; D001681:Biological Assay; D003300:Copper / Q000494:pharmacology; D000458:Cyanobacteria; D000087522:Cyanobacteria Toxins; D004355:Drug Stability; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008387:Marine Toxins / Q000378:metabolism* / Q000528:radiation effects / Q000633:toxicity; D051379:Mice; D052998:Microcystins; D015394:Molecular Structure; D010100:Oxygen / Q000494:pharmacology; D010782:Photolysis; D013056:Spectrophotometry, Ultraviolet; D013472:Sunlight; D014326:Tropanes
D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D008387:Marine Toxins; D052998:Microcystins; D014326:Tropanes; D003300:Copper; C509783:anatoxin a; D007501:Iron; D010100:Oxygen