Scorpion venom is a rich source of biologically active components and various peptides with high-potential therapeutic use that have been characterized for their antimicrobial and antiproliferative activities. Stigmurin is a peptide identified from the Tityus stigmurus venom gland with high antibacterial and antiproliferative activities and low toxicity. Amino acid substitutions in peptides without a disulfide bridge sequence have been made with the aim of reducing their toxicity and increasing their biological activities. The purpose of this study was to evaluate the structural conformation and structural stability, as well as antimicrobial, antiproliferative, and hemolytic activities of two peptide analogs to Stigmurin, denominated StigA6 and StigA16. In silico analysis revealed the α-helix structure for both analog peptides, which was confirmed by circular dichroism. Data showed that the net charge and hydrophobic moment of the analog peptides were higher than those for Stigmurin, which can explain the increase in antimicrobial activity presented by them. Both analog peptides exhibited activity on cancerous cells similar to the native peptide; however, they were less toxic when tested on the normal cell line. These results reveal a potential biotechnological application of the analog peptides StigA6 and StigA16 as prototypes to new therapeutic agents.

Anionic Peptides are molecules rich in aspartic acid (Asp) and/or glutamic acid (Glu) residues in the primary structure. This work presents, for the first time, structural characterization and biological activity assays of an anionic peptide from the venom of the scorpion Tityus stigmurus, named TanP. The three-dimensional structure of TanP was obtained by computational modeling and refined by molecular dynamic (MD) simulations. Furthermore, we have performed circular dichroism (CD) analysis to predict TanP secondary structure, and UV-vis spectroscopy to evaluate its chelating activity. CD indicated predominance of random coil conformation in aqueous medium, as well as changes in structure depending on pH and temperature. TanP has chelating activity on copper ions, which modified the peptide's secondary structure. These results were corroborated by MD data. The molar ratio of binding (TanP:copper) depends on the concentration of peptide: at lower TanP concentration, the molar ratio was 1:5 (TanP:Cu), whereas in concentrated TanP solution, the molar ratio was 1:3 (TanP:Cu). TanP was not cytotoxic to non-neoplastic or cancer cell lines, and showed an ability to inhibit the in vitro release of nitric oxide by LPS-stimulated macrophages. Altogether, the results suggest TanP is a promising peptide for therapeutic application as a chelating agent.

The presence of bioactive peptides in animal venoms has been targeted in scientific research for assessing biological activities, as well as mechanisms of action. A recent study by our group observed hypotensive action of TistH (Tityus stigmurus Hypotensin), a peptide deduced from the transcriptome of T. stigmurus venom gland. The present study aims to analyze TistH structure properties and to evaluate its toxicity on normal and tumor cells, its in vitro antimicrobial activity, as well as its inflammatory effect. Circular dichroism analyses of TistH showed a general predominance of α-helix conformation in TFE (20-70%) and structural stability to pH variations. TistH was not cytotoxic to normal cell lines (3T3, RAW and HEK), and also not to cancer cell lines (HeLa, B16, 786-0, SiHa and HepG2). The peptide did not present inflammatory activity up to 6 h after administered subcutaneously to Swiss mice. It was observed that concentrations of 4-1024 μg/mL of TistH produced no inhibition against the bacteria Staphylococcus aureus, Staphylococcus epidermidis e Pseudomonas aeruginosa. The results of antifungal assays showed a moderate activity of TistH against Candida albicans strain LM-108 and the filamentous fungus Trichophyton rubrum LM-640, with growth inhibition at a concentration of 1024 μg/mL. In contrast, the peptide presented a greater activity (MIC 128 μg/mL) against C. albicans LM-106, Candida tropicalis ATCC 13308 and Aspergillus flavus strains LM-247 and LM-26, fungi that cause oral and vaginal infections, candidiasis and respiratory allergies, respectively. The present data contribute to a better understanding of TistH and its possible use as a bioactive compound. This multifunctional peptide is capable of acting as anti-hypertensive, as well as to inhibit the growth of fungal strains, having low toxicity, which suggests its safety for using as a pharmacological agent.

O farmacêutico é o profissional responsável por orientar a comunidade sobre o uso racional de medicamentos, por meio da atenção farmacêutica. A prática da automedicação está relacionada ao estoque em domicílio de medicamentos, que favorece à problemática de seu descarte incorreto. Quando vencidos ou fora de uso, os medicamentos são descartados, na maioria das vezes, em locais inapropriados, afetando o meio ambiente. O trabalho teve por objetivo elaborar uma estratégia de descarte consciente de medicamentos durante a semana científica em uma faculdade privada, na cidade de Natal, RN, bem como avaliar o perfil dos medicamentos descartados. Trata-se de um estudo quantitativo, observacional e descritivo. A coleta dos medicamentos ocorreu em junho de 2019, durante a semana científica. Posteriormente foi realizada a contagem dos medicamentos recolhidos, separando-os por forma farmacêutica e em seguida verificou-se o quantitativo de medicamentos genéricos. Um total de 303 medicamentos vencidos ou fora de uso foram recolhidos, sendo 220 na forma farmacêutica sólida, 66 líquidos, e 17 semissólidos. Do total recolhido, apenas 51 eram genéricos. O estabelecimento de estratégias que facilitem o descarte racional de medicamentos no âmbito acadêmico possibilita uma alternativa para diminuir o acúmulo de medicamentos vencidos ou fora de uso em domicílio, bem como evita que estes sejam descartados em locais inapropriados.

Anionic peptides of scorpions are molecules rich in aspartic and/or glutamic acid residues and correspond to a class of peptides without disulfide bonds that are still little explored. TanP is a linear anionic peptide (50 amino acid residues and net charge −20) present in the venom gland of the scorpion, Tityus stigmurus, with chelating properties for Cu2+ ion and immunomodulatory properties. The therapeutic application of chelating molecules is related to cases of acute or chronic intoxication by metals, neurodegenerative diseases, hematological diseases, healing of skin wounds, cardiovascular diseases, and cancer. In this approach, the chelating activity of TanP was evaluated in relation to new metal ions (Fe2+ and Zn2+) of biological importance, as well as its antioxidant, hemostatic, immunomodulatory, and healing potential, aiming to expand the biological and biotechnological potential of this peptide. TanP (25 µM) was able to form stable complexes with Fe2+ in a ratio of 1:5 (TanP: Fe2+). Theoretical results suggest that TanP can work as a sensor to identify and quantify Fe2+ ions. The fluorescence intensity of TanP (1.12 µM) decreased significantly after the addition of Fe2+, obtaining the highest ratio 1: 7.4 (TanP: Fe2+) that led to the lowest fluorescence intensity. For Zn2+, no relevant spectral change was noted. TanP (50 µM) showed a maximum of 3% of hemolytic activity, demonstrating biocompatibility, as well as exhibiting a 1,1-diphenyl-2-picrylhydrazyl radical–scavenging activity of above 70% at all the concentrations tested (1–25 μM), and 89.7% iron-chelating activity at 25 μM and 96% hydroxyl radical–scavenging activity at 73.6 μM. In addition, TanP (12.5 and 25 µM) revealed an anticoagulant effect, prolonging the clotting time in prothrombin time and activated partial thromboplastin time assays, with no fibrinogenolytic activity. TanP (12.5 and 25 µM) induced the release of TNF-α by murine macrophages, in the absence of lipopolysaccharides, with a concentration-dependent increase and also stimulated the migration of 3T3 cells in the in vitro healing assay. Thus, TanP revealed a multifunctional potential, being useful as a prototype for the development of new therapeutic and biotechnological agents.