Behavioral Effects of Extracts and Compounds Isolated from Erythrina Velutina (Mulungu) in Rats

In many countries and also Brazil, the extracts or infusions of fresh plants are used to treat common infections or diseases, mainly in the countryside and among the indigenous people. The popular knowledge of the medicinal plants contributes a lot to the benefit of the human health, and directly could help for new discoveries of medicines. The antinociceptive effect is an important target for new active compounds to be searched, in part due to the increase in human life expectation, on the other hand for new cheaper compounds to the low income population, and finally, with new properties or less side effects. In the current work, extracts obtained from Erythrina velutina seeds, commonly used against snake bites, were tested for the capacity to neutralize the nociceptive effects induced by the hot plate test and anxiety behavior with combination of the open field and the elevated plus maze. Tested animals (rats) with different extracts of seed demonstrated analgesic effect with the animal on hot plate. The animals also increased wandering in the open field and even the numbers of entries and the time spent in the open arms of the elevated plus maze. That demonstrated that lesser anxiety levels allow longer and more frequent exploration periods of the open arms, suggesting that Erythrina velutina has strong anxiolytic properties compared to the control anxiolytic diazepam, it could serve as a new approach for the treatment anxiety.

Characterization of two vasoactive peptides isolated from the plasma of the snake Crotalus durissus terrificus.

Incubation of plasma from the snake Crotalus durissus terrificus (CDTP) with trypsin generated two hypotensive peptides. The primary structure of the peptides was established for two sequences as: (Ser-Ile-Pro-Gln-Ala-Pro-Thr-Ser-Asn-Leu-Ile-Glu-Ala-Thr-Lys) and (Lys-Pro-Asp-Ala-Asn-Gln-Val-Leu-Ile-Gln-Val-Ile-Gly-Val). These peptides display homology with fragments of albumin from Trimeresurus flavoviridis. Bolus intra-arterial injection of the purified or the synthetic peptide produced a strong and sustained vasopressor response in the anaesthetized snake (CDT) and rats (Wistar); this hypotensive effect was also potentiated by captopril-an angiotensin-converting (0.1 mg/kg) enzyme inhibitor.

Actions of the Kunitz-type serine protease inhibitor Amblyomin-X on VEGF-A-induced angiogenesis.

Amblyomin-X is a Kunitz-type serine protease inhibitor (Kunitz-type SPI) designed from the cDNA library of the Amblyomma cajennense tick, which displays in vivo anti-tumor activities. Here, the mechanisms of actions of Amblyomin-X in vascular endothelial growth factor A (VEGF-A)-induced angiogenesis were characterized. Topical application of Amblyomin-X (10 or 100 ng/10 µl; each 48 h) inhibited VEGF-A-induced (10 ng/10 µl; each 48 h) angiogenesis in the dorsal subcutaneous tissue in male Swiss mice. Moreover, similar effect was observed in the VEGF-A-induced angiogenesis in the chicken chorioallantoic membrane (CAM). Additional in vitro assays in t-End cells showed that Amblyomin-X treatment delayed the cell cycle, by maintaining them in G0/G1 phase, and inhibited cell proliferation and adhesion, tube formation and membrane expression of the adhesion molecule platelet-endothelial cell adhesion molecule-1 (PECAM-1), regardless of mRNA synthesis. Together, results herein reveal the role of Kunitz-type SPI on in vivo VEGF-A-induced angiogenesis, by exerting modulatory actions on endothelial cell proliferation and adhesion, especially on membrane expression of PECAM-1. These data provide further mechanisms of actions of Kunitz-type SPI, corroborating their relevance as scientific tools in the design of therapeutic molecules.

Effects of three vasoactive peptides isolated from the plasma of the snake Bothrops jararaca.

Incubation of plasma from the snake Bothrops jararaca (BJP) with trypsin generated two hypotensive peptides. The primary structure of the peptides was established for three sequences as: Asn-Pro-Phe-Val-Asp-Ala (fraction 13), Ser-Lys-Pro-Asn-Met-Ser-Asp-Glu-Ser-Leu-Ala-Val-Ala-Ile (fraction 14), Asn-Pro-Phe- Val-Asp-Ala (fraction 15). These peptides display homology with fragments of albumin from Trimeresurus flavoviridis. A bolus intra-arterial injection of the purified or the synthetic peptide produced a strong and sustained vasopressor response in the anaesthetized snake B. jararaca and Wistar rats; this hypotensive effect was also potentiated by captopril, an angiotensin-converting enzyme inhibitor (0.1 mg/kg). The natural concentrations of these peptides in plasma need to be determined and could play a physiological role in snake blood pressure regulation.

Neurotransmitter evaluation in the hippocampus of rats after intracerebral injection of TsTX scorpion toxin

TsTX is an á-type sodium channel toxin that stimulates the discharge of neurotransmitters from neurons. In the present study we investigated which neurotransmitters are released in the hippocampus after TsTX injection and if they are responsible for electrographic or histopathological effects. Microdialysis revealed that the toxin increased glutamate extracellular levels in the hippocampus; however, levels of gamma-aminobutyric acid (GABA), glycine, 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were not significantly altered. Neurodegeneration in pyramidal cells of hippocampus and electroencephalographic alterations caused by the toxin were blocked by pretreatment with riluzole, a glutamate release inhibitor. The present results suggest a specific activity of TsTX in the hippocampus which affects only glutamate release.