Antillatoxin and kalkitoxin, ichthyotoxins from the tropical cyanobacterium Lyngbya majuscula, induce distinct temporal patterns of NMDA receptor-mediated neurotoxicity.

Curacin-A, antillatoxin and kalkitoxin, natural products from the marine cyanobacterium Lyngbya majuscula, were tested for neurotoxicity in primary cultures of rat cerebellar granule neurons. Curacin-A was non-toxic, whereas antillatoxin and kalkitoxin produced concentration-dependent cytotoxicity with LC50 values of 20.1+/-6.4 and 3.86+/-1.91 nM, respectively. Antillatoxin neurotoxicity was produced acutely, whereas kalkitoxin caused a delayed neurotoxic response. The cytotoxicity produced by both antillatoxin and kalkitoxin was prevented by the non-competitive NMDA receptor antagonists dextrorphan and MK-801.