Biological effects of tolytoxin (6-hydroxy-7-O-methyl-scytophycin b), a potent bioactive metabolite from cyanobacteria.

Tolytoxin, a macrocyclic lactone, is a potent antifungal antibiotic, exhibiting MICs in the range of 0.25 to 8 nanomolar. Tolytoxin also inhibits the growth of a variety of mammalian cells at similar doses, without specific inhibition of macromolecular synthesis. The effects in mammalian cells are primarily cytostatic, with cell death being time- and dose-dependent. Tolytoxin is highly toxic to mice, exhibiting an LD50 (ip) of 1.5 mg/kg. No antibacterial, antiviral, or hemolytic activities were observed.