Data/hora: 01/06/2024 14:38:35

Provedor de dados: | 80
País: | Brazil
Título: | Synthesis and antimicrobial evaluation of two peptide LyeTx I derivatives modified with the chelating agent HYNIC for radiolabeling with technetium-99m
Autores: | Fuscaldi,Leonardo Lima; Santos,Daniel Moreira dos; Pinheiro,Natália Gabriela Silva; Araújo,Raquel Silva; Barros,André Luís Branco de; Resende,Jarbas Magalhães; Fernandes,Simone Odília Antunes; Lima,Maria Elena de; Cardoso,Valbert Nascimento.
Data: | 2016-01-01
Ano: | 2016
Palavras-chave: | Septic and aseptic inflammation; Differential diagnosis; Antimicrobial peptides LyeTx I derivatives; MALDI-ToF-MS RP-HPLC; Technetium-99m; HYNIC EDDA Tricine.
Resumo: | Abstract  Background  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 99mTc.  Methods  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 99mTc 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 &lt; 0.05).  Results  Both LyeTx I derivatives were suitably synthesized and purified, as shown by RP-HPLC and MALDI-ToF-MS analysis. The microbiological test showed that HYNIC-LyeTx I (N-terminal modification) did not inhibit bacterial growth, whereas LyeTx I-K-HYNIC (C-terminal modification) showed a MIC of 5.05 μmol.L−1 (S. aureus) and 10.10 μmol.L−1 (E. coli). Thus, only the latter was radiolabeled with 99mTc. The radiochemical purity analysis of LyeTx I-K-HYNIC-99mTc showed that the optimal radiolabeling conditions (10 μg of LyeTx I-K-HYNIC; 250 μg of SnCl2. 2H2O; pH = 7; heating for 15 min) yielded a radiochemical purity of 87 ± 1 % (n= 3). However, RP-HPLC data suggested 99mTc transchelation from LyeTx I-K-HYNIC to the co-ligands (tricine and EDDA).  Conclusions  The binding of HYNIC to the N-terminal portion of LyeTx I seems to affect its activity against bacteria. Nevertheless, the radiolabeling of the C-terminal derivative, LyeTx I-K-HYNIC, must be better investigated to optimize the radiolabeled compound, in order to use it as a specific imaging agent to distinguish septic and aseptic inflammation.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1678-91992016000100312
Editor: | Centro de Estudos de Venenos e Animais Peçonhentos
Relação: | 10.1186/s40409-016-0070-y
Formato: | text/html
Fonte: | Journal of Venomous Animals and Toxins including Tropical Diseases  v.22 2016
Fonte: | info:eu-repo/semantics/openAccess