ABSTRACT
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 alpha-helix conformation in TFE (20-70%) and structural stability to pH variations. TistH was not cytotoxic to normal cell lines (3T3, RAW and HER), 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 mu g/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 mu g/mL. In contrast, the peptide presented a greater activity (MIC 128 mu g/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. (C) 2016 Elsevier Ltd. All rights reserved.
Subject(s)
Allergy and Immunology , Toxicology , PharmacologyABSTRACT
Microbial resistance to conventional antibiotics is a public health problem worldwide, motivating the search for new therapeutic alternatives in varied natural sources. Cationic peptides without disulfide bridges from scorpions have been targeted in this context, mainly due to their multifunctional action and the limited ability of microorganisms to develop resistance against them. The present study was focused on Stigmurin and TsAP-2, cationic peptides found in the transcriptome of the venom gland from the scorpion Tityus stigmurus. The aims were: to assess the secondary structure of TsAP-2 and the structural stability of both peptides by circular dichroism; to evaluate their antiproliferative effect, and antimicrobial activities in vitro, ex vivo and in vivo; and to investigate their therapeutic potential in a murine model of polymicrobial sepsis. Stigmurin and TsAP-2 secondary structures responded similarly to environment polarity changes, and were stable to temperature and pH variation. Both peptides showed antiproliferative effect on tumor cells. TsAP-2 showed lower cytotoxicity to normal cells, and had a mitogenic activity on murine macrophages. Stigmurin demonstrated bactericidal and bacteriostatic activity, depending on the microorganism, whereas TsAP-2 had bactericidal action upon different bacterial strains analyzed. Both peptides were able to reduce leukocyte migration, TNF-alpha levels and microorganism load in the peritoneal cavity after induction of experimental sepsis, decreasing inflammation in the lung and cecum of septic animals. TsAP-2 also reduced the release of nitric oxide in the peritoneal cavity. Taken together, these data suggest that Stigmurin and TsAP-2 are structurally stable molecules and are efficient in the control of the infectious focus in polymicrobial sepsis, with potential use as a prototype for the rational design of novel therapeutic agents. (C) 2016 Elsevier Ltd. All rights reserved.
