**8. Neurotoxic compounds**

### **8.1 Antillatoxin**

*Lyngbya majuscula* served as the source for the extraction of the crude extract of Curacao, found to be highly ichthyotoxic and molluscicidal. This extract was then fractionation and subsequent purification led to the finding of the potent lipopeptide ichthyotoxin, antillatoxin. Antillatoxin is one of the most ichthyotoxic metabolites isolated from a marine cyanobacterium with an LD50 value of 0.05 g/ mL. Pharmacological studies showed that the antillatoxin was neurotoxic and rapidly morphologically changes in rat cerebellar granule neurons (CGC's), also includes bebling of neurite membranes. Toxic effects of Antillatoxin was remarkably reduced, when the cells were treated with NMDA receptor antagonists like dextrophan [65]. Thus, its toxic effects were mediating by NMDA receptor dependent mechanism. Antillatoxin shown to be a powerful activator of voltage gated sodium channels and resembled brevetoxin. Unique biological activity of antillatoxin was mainly combined with its structure [66].

### **8.2 Antillatoxin**

A lipopeptide isolated from *Lyngbya majuscula*, which is closely related to the antillatoxin with a larger B-methyl homophenylalanine instead of N-methyl valine residues was termed as Antillatoxin B. It is collectively found to be similar to ichthyotoxic (LC 50 = 1.0 M) and a potent activator of voltage gated sodium channels in mouse neuroblastoma cells [67].
