Table 2.
Principal groups of cyanobacterial toxins, their acute toxicities, structures and known producers.
| Toxins (LD50-acute toxicityA) | Structure (number of variants) | Activity | Toxigenic genera |
|---|---|---|---|
| Hepatotoxins | |||
| Microcystins (25 to ~ 1000) | Cyclic heptapeptides (71) | Hepatotoxic, protein phosphatase inhibition, membrane integrity and conductance disruption, tumour promoters | MicrocystisBCD, AnabaenaBCD, NostocBC, PlanktothrixBCD, AnabaenopsisB, HapalosiphonBC |
| Nodularins (30 to 50) | Cyclic pentapeptides (9) | Hepatotoxic, protein phosphatase inhibition, membrane integrity and conductance disruption, tumour promoters, carcinogenic | NodulariaBCD |
| Cylindrospermopsins (200 to 2100) | Guanidine alkaloids (3) | Necrotic injury to liver (also to kidneys, spleen, lungs, intestine), protein synthesis inhibitor, genotoxic | CylindrospermopsisBC, AphanizomenonBC, AnabaenaC, RaphidiopsisBC, UmezakiaB |
| Neurotoxins | |||
| Anatoxin-a (250) | Tropane-related alkaloids (5) | Postsynaptic, depolarising neuromuscular blockers | AphanizomenonB, AnabaenaBCD, RaphidiopsisBC, OscillatoriaBC, PlanktothrixBC, CylindrospermumB |
| Anatoxin-a(S) (40) | Guanidine methyl phosphate ester (1) | Acetylcholinesterase inhibitor | AnabaenaBC |
| Saxitoxins (10 to 30) | Carbamate alkaloids (20) | Sodium channel blockers | AphanizomenonBC, AnabaenaBC, PlanktothrixBC, CylindrospermopsisBC, LyngbyaBC |
| Dermatotoxins (irritants) and cytotoxins | |||
| Lyngbyatoxin-a | Alkaloid (1) | Inflammatory agent, protein kinase C aktivator | LyngbyaB, SchizotrixB, OscillatoriaB |
| Aplysiatoxin | Alkaloids (2) | Inflammatory agents, protein kinase C aktivators | LyngbyaB, SchizotrixB, OscillatoriaB |
| Endotoxins (irritants) | |||
| Lipopolysaccharides | Lipopoly-saccharides | Inflammatory agents, gastrointestinal irritants | All cyanobacteria? |
A
acute toxicity in mouse bioassay (i.p. exposure, LD50-µg/kg body weight);
B
toxin identified in natural population with dominant genera;
C
toxin identified in non-axenic monocyanobacterial culture (not bacteria free);
D
toxin identified in axenic monocyanobacterial culture (cyanobacteria free).