Arthropods are the most diverse animal group on the planet, and occupy almost all ecological niches. Venomous arthropods are a rich source of bioactive compounds evolved for prey capture and defense against predators and/or microorganisms. These highly potent chemical arsenals represent an available source for new insecticidal compounds as they act selectively on their molecular targets. These toxins affect the invertebrate nervous system and, until the moment, several insecticidal compounds belonging to the class of peptides or polyamine-like compounds have been purified and characterized from the venom of arachnids and hymenopterans. This review focuses on invertebrate-specific peptide neurotoxins that have been isolated from the venom ofspiders, scorpions, centipedes, ants, and wasps, discussing their potential in pest control and as invaluable tools in neuropharmacology.

Neurotoxicity is a major symptom of envenomation caused by Brazilian coral snake Micrurus frontalis. Due to the small amount of material that can be collected, no neurotoxin has been fully sequenced from this venom. In this work we report six new three-finger like toxins isolated from the venom of the coral snake M. frontalis which we named Frontoxin (FTx) I-VI. Toxins were purified using multiple steps of RP-HPLC. Molecular masses were determined by MALDI-TOF and ESI ion-trap mass spectrometry. The complete amino acid sequence of FTx II, III, IV and V were determined by sequencing of overlapping proteolytic fragments by Edman degradation and by de novo sequencing. The amino acid sequences of FTx I, II, III and VI predict 4 conserved disulphide bonds and structural similarity to previously reported short-chain alpha-neurotoxins. FTx IV and V each contained 10 conserved cysteines and share high similarity with long-chain alpha-neurotoxins. At the frog neuromuscular junction FTx II, III and IV reduced miniature endplate potential amplitudes in a time-and concentration-dependent manner suggesting Frontoxins block nicotinic acetylcholine receptors.

Analgesic therapy is based on the sequential treatment of pain, in which opioids are drugs of last resource and known to be highly effective, but are also responsible for undesirable side effects, tolerance and addiction. There is a need for new drugs with alternative targets in order to minimize side effects and improve treatment efficacy. Mastoparans are an abundant class of peptides in wasp venom and have shown great potential as new drugs, as well as being excellent tools for the study of G-protein-coupled receptors. The objective of this study was to investigate the antinociceptive activity of the mastoparan Agelaia-MP I and the mechanisms involved. Agelaia-MP I (MW 1565 Da) showed dose-dependent antinociceptive activity in mice submitted to i.c.v. injection in two different models. The highest dose produced a maximum effect for up to 4 h, and nociception remained low three days after injection. Further experiments showed that Agelaia-MPI induced partial and reversible blockade of the amplitude of action potential, probably interacting with voltage-gated sodium channels. These results revealed the significant potential impact of compounds isolated from wasp venom on the central nervous system (CNS). In addition, the antinociceptive effect described here is a novel activity for mastoparans.

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