A comparison of toxins isolated from the cyanobacteria Oscillatoria agardhii and Microcystis aeruginosa.

1. A toxin isolated from a strain of Oscillatoria agardhii var. was compared to a peptide toxin isolated from Microcystis aeruginosa. 2. The Oscillatoria toxin possessed similar hepatotoxic properties on mice as the Microcystis toxin but had a higher LD50 than the latter; 320 micrograms/kg compared to 43 micrograms/kg (i.p. mouse), respectively. 3. Ultra-violet and infra-red spectra showed that the Oscillatoria toxin is a peptide which is not identical to the Microcystis toxin. 4. The spectra also indicated some structural similarities in these toxins.