Synthesis and antimicrobial evaluation of two peptide LyeTx I derivatives modified with the chelating agent HYNIC for radiolabeling with technetium-99m

• Published in: The journal of venomous animals and toxins including tropical diseases 2016-04, Vol.22 (1), p.16-16, Article 16
• Main Authors: Fuscaldi, Leonardo Lima, Dos Santos, Daniel Moreira, Pinheiro, Natália Gabriela Silva, Araújo, Raquel Silva, de Barros, André Luís Branco, Resende, Jarbas Magalhães, Fernandes, Simone Odília Antunes, de Lima, Maria Elena, Cardoso, Valbert Nascimento
• Format: Article
• Language: English
• Subjects: Amino acids; Antimicrobial agents; Antimicrobial peptides; Antimicrobial peptides LyeTx I derivatives; Chelating agents; Chemical synthesis; Chromatography; Differential diagnosis; E coli; Gamma rays; HYNIC EDDA Tricine; Inflammation; Innovations; MALDI-ToF-MS RP-HPLC; Microorganisms; Peptides; Properties; Radioactive tracers; Radioisotopes; Septic and aseptic inflammation; Solvents; Synthetic products; Technetium-99m; TOXICOLOGY; TROPICAL MEDICINE; Variance analysis
• ISSN: 1678-9199; 1678-9199
• DOI: 10.1186/s40409-016-0070-y

Current diagnostic methods and imaging techniques are not able to differentiate septic and aseptic inflammation. Thus, reliable methods are sought to provide this distinction and scintigraphic imaging is an interesting option, since it is based on physiological changes. In this context, radiolabeled antimicrobial peptides have been investigated as they accumulate in infectious sites instead of aseptic inflammation. The peptide LyeTx I, from the venom of Lycosa erythrognatha, has potent antimicrobial activity. Therefore, this study aimed to synthesize LyeTx I derivatives with the chelating compound HYNIC, to evaluate their antimicrobial activity and to radiolabel them with (99m)Tc. Two LyeTx I derivatives, HYNIC-LyeTx I (N-terminal modification) and LyeTx I-K-HYNIC (C-terminal modification), were synthesized by Fmoc strategy and purified by RP-HPLC. The purified products were assessed by RP-HPLC and MALDI-ToF-MS analysis. Microbiological assays were performed against S. aureus (ATCC® 6538) and E. coli (ATCC® 10536) in liquid medium to calculate the MIC. The radiolabeling procedure of LyeTx I-K-HYNIC with (99m)Tc was performed in the presence of co-ligands (tricine and EDDA) and reducing agent (SnCl2 (.) 2H2O), and standardized taking into account the amount of peptide, reducing agent, pH and heating. Radiochemical purity analysis was performed by thin-layer chromatography on silica gel strips and the radiolabeled compound was assessed by RP-HPLC and radioactivity measurement of the collected fractions. Data were analyzed by ANOVA, followed by Tukey test (p-values