Snake venoms are a mixture of complex proteins, which have many physical and pharmacological properties. Photochemical detoxification has been suggested to generate photooxidized Echis carinatus venom product (POECVP). Antigenically-active photooxidized species of Echis carinatus venom could be obtained by exposing the venom to ultraviolet radiation (UVR) in the presence of methylene blue. The aim of the present study was to evaluate the effects of POECVP on learning, memory and stress in rats. Detoxification of the photooxidized venom was evident since the POECVP-treated group had longer survival time than the group of mice treated with Echis carinatus venom product (ECVP) following intraperitoneal and intracerebral injections. Photooxidized Echis carinatus venom product showed antidepressant activity by prolonging sleep onset and shortening the duration of pentobarbitone-induced hypnosis in mice. In single and chronic dose studies with rats, we observed that POECVP significantly decreased the time needed to reach food in T-maze, shortened transfer latency in elevated plus-maze, and decreased immobility time in forced swim test. We concluded that although there is a possibility of employing POECVP in the treatment of depressive and chronic degenerative illnesses as a nonherbal and nonsynthetic alternative for patients not responding to the available therapy, further investigation is still needed.

Buthus C56 toxin from venom of the Indian red scorpion Mesobuthus tamulus was studied for its effects on spontaneous miniature excitatory junctional potentials (MEJP) on Drosophila larval neuromuscular junctions. C56 toxin was isolated on CM-Cellulose with linear gradient of ammonium acetate buffer, pH 6.0. Toxin purity was determined on SDS slab gel electrophoresis. Effective concentration of C56 toxin was based on contraction paralysis units (CPU) in Drosophila 3rd instar larvae by microinjection (0.1 CPU/ml = 2 x 10-6 g/ml). The toxin-induced excitatory junctional potentials were studied for calcium dependency (0.2 mM to 1.2 mM Ca2+) in Drosophila Ringer. Excitatory junctional potential amplitude was increased with increasing calcium concentration; maximum increase in the frequency at 0.4 mM Ca2+/4 mM Mg2+ Drosophila Ringer. It was suggested that while amplitude of excitatory junctional potentials was increased with concentration, maximum frequency increase at 0.4 mMCa2+/4 mM Mg2+ Drosophila Ringer may be due to augmented Ca2+ influx in 0.4 mM Ca2+, when NMDA receptors were maximally activated in C56 toxin-treated Drosophila larval neuromuscular junction.

The photodynamic action of UV sensitized methylene blue (MB) was studied on the venom of Thailand cobra Naja siamensis. The reaction mixture comprising phosphate buffer (B), methylene blue (S), and venom protein (P) was exposed to UVR (ultra violet radiation) for 2 hours at 37°C. Stable excited species (S’) were generated by photodynamic action. These in B environment produced reduced substates SH2 and photooxidised products PO in the presence of atmospheric oxygen. Increased absorbance (OD) of the reaction mixture after UVR with a corresponding loss of protein was suggested to be due to the formation of photooxidised venom products. The detoxification profile of venom protein using visible radiation in the presence of MB and oxygen appeared similar to the profile using UVR.