Cyanotoxin Fact Page

Cyanotoxins can be classified into categories that reflect their biological effects on the systems and organs that they affect most strongly. Each cyanotoxin can be produced by more than one cyanobacterial species; likewise, several toxins can be found within the same species. Toxigenic Cyanobacteria listed below are from marine, brackish and freshwaters. LD₅₀ (Lethal Dose) is the amount of cyanotoxin sufficient to kill 50% of the tested population (here mice); usually within a certain time.

Hepatotoxins

Hepatotoxins disrupt proteins that keep the liver functioning, may act slowly (days or weeks later).

• Microcystins (>80 structural variants)
  • LD₅₀: 25-60 μg kg^-1 of body weight
  • Potent carcinogen (liver, kidneys)
  • Known producers: Microcystis aeruginosa, M. viridis, Anabaena flos-aquae, A. circinalis, Planktothrix agardhii, P. isothrix, Oscillatoria limosa, Anabaenopsis millerii, Nostoc, Aphanocapsa spp.

• Nodularins (9)
  • LD₅₀: 60 μg kg^-1
  • Known producer: Nodularia spumigena

• Cylindrospermopsins (3)
  • LD₅₀: 300 μg kg^-1
  • Known producers: Aphanizomenon ovalisporum, Cylindrospermopsis raciborskii, Umezakia natans

Neurotoxins

Neurotoxins cause rapid paralysis of skeletal and respiratory muscles.

• Anatoxin-a (5)
  • LD₅₀: 200-250 μg kg^-1
  • Known producers: Anabaena flos-aquae, A. planctonica , A. spiroides, A. circinalis, Aphanizomenon, Cylindrospermum, Microcystis, Oscillatoria spp.

• Anatoxin-a(S) (1)
  • LD₅₀: 20 μg kg^-1
  • Known producers: Anabaena flos-aquae, A. lemmermannii

• Saxitoxins (21)
  • LD₅₀: 10 μg kg^-1
  • Potent neurotoxin; Paralytic Shellfish Poisoning (PSP)
  • Known producers: Anabaena flos-aquae, A. lemmermannii, Aphanizomenon flos-aquae, Cylindrospermopsis raciborskii, Lyngbya wollei, Planktothrix agardhii

• β-N-methylamino-L-alanine (BMAA)
  • Neurodegenerative agents, causative of Amyotrophic Lateral Sclerosis (Lou Gehrig’s Disease) and Parkinsonism-Dementia Complex (ALS/PDC)
  • Known producers: Microcystis , Anabaena, Nostoc, Planktothrix spp.

• Microviridin J
  • Toxicological profile partially known
  • Known producer: Microcystis spp.

Dermatotoxins

Dermatotoxins produce rashes and other skin reactions (hours or days). Potent irritants, vesicants and carcinogens.

• Lyngbyatoxin-a (1)
  • Potent irritant and vesicant, aka seaweed dermatitis
  • Known producer: Moorea producta (ex- Lyngbya majuscula)
• Aplysiatoxins (2)
  • Potent tumor promoters
  • Known producer: Lyngbya majuscula, Oscillatoria nigro-viridis

Endotoxins

Endotoxins inflame gastrointestinal epithelium. They are pyrogenic (fever) and induce immune response. At high enough concentrations in blood, endotoxins are lethal (septic shock).

• Lipopolysaccharides (LPS)
  • All Cyanobacteria