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Bouchet A.M.,Biomimetic Systems | Iannucci N.B.,University of Buenos Aires | Iannucci N.B.,Therapeutic Peptides | Pastrian M.B.,University of Buenos Aires | And 6 more authors.
Colloids and Surfaces B: Biointerfaces | Year: 2014

Substitution of Ala 108 and Ala 111 in the 107-115 human lysozyme (hLz) fragment results in a 20-fold increased anti-staphylococcal activity while its hemolytic activity becomes significant (30%) at very high concentrations. This analog displays an additional positive charge near the N-terminus (108) and an extra Trp residue at the center of the molecule (111), indicating that this particular amino acid sequence improves its interaction with the bacterial plasma membrane. In order to understand the role of this arrangement in the membrane interaction, studies with model lipid membranes were carried out.The interactions of peptides, 107-115 hLz and the novel analog ([K108W111]107-115 hLz) with liposomes and lipid monolayers were evaluated by monitoring the changes in the fluorescence of the Trp residues and the variation of the monolayers surface pressure, respectively. Results obtained with both techniques revealed a significant affinity increase of [K108W111]107-115 hLz for lipids, especially when the membranes containing negatively charged lipids, such as phosphatidylglycerol. However, there is also a significant interaction with zwitterionic lipids, suggesting that other forces in addition to electrostatic interactions are involved in the binding. The analysis of adsorption isotherms and the insertion kinetics suggest that relaxation processes of the membrane structure are involved in the insertion process of novel peptide [K108W111]107-115 hLz but not in 107-115 hLz, probably by imposing a reorganization of water at the interphases.In this regard, the enhanced activity of peptide [K108W111]107-115 hLz may be explained by a synergistic effect between the increased electrostatic forces as well as the increased hydrophobic interactions. © 2013 Elsevier B.V.


PubMed | University of Louisville, Therapeutic Peptides, Auburn University and Alabama State University
Type: Journal Article | Journal: Journal of nanobiotechnology | Year: 2016

Due to increasing antibiotic resistance, the use of silver coated single walled carbon nanotubes (SWCNTs-Ag) and antimicrobial peptides (APs) is becoming popular due to their antimicrobial properties against a wide range of pathogens. However, stability against various conditions and toxicity in human cells are some of the major drawbacks of APs and SWCNTs-Ag, respectively. Therefore, we hypothesized that APs-functionalized SWCNTs-Ag could act synergistically. Various covalent functionalization protocols described previously involve harsh treatment of carbon nanotubes for carboxylation (first step in covalent functionalization) and the non-covalently functionalized SWCNTs are not satisfactory.The present study is the first report wherein SWCNTs-Ag were first carboxylated using Tri sodium citrate (TSC) at 37C and then subsequently functionalized covalently with an effective antimicrobial peptide from Therapeutic Inc., TP359 (FSWCNTs-Ag). SWCNTs-Ag were also non covalently functionalized with TP359 by simple mixing (SWCNTs-Ag-M) and both, the FSWCNTs-Ag (covalent) and SWCNTs-Ag-M (non-covalent), were characterized by Fourier transform infrared spectroscopy (FT-IR), Ultraviolet visualization (UV-VIS) and transmission electron microscopy (TEM). Further the antibacterial activity of both and TP359 were investigated against two gram positive (Staphylococcus aureus and Streptococcus pyogenes) and two gram negative (Salmonella enterica serovar Typhimurium and Escherichia coli) pathogens and the cellular toxicity of TP359 and FSWCNTs-Ag was compared with plain SWCNTs-Ag using murine macrophages and lung carcinoma cells.FT-IR analysis revealed that treatment with TSC successfully resulted in carboxylation of SWCNTs-Ag and the peptide was indeed attached to the SWCNTs-Ag evidenced by TEM images. More importantly, the present study results further showed that the minimum inhibitory concentration (MIC) of FSWCNTs-Ag were much lower (~7.8-3.9g/ml with IC50: ~4-5g/ml) compared to SWCNTs-Ag-M and plain SWCNTs-Ag (both 62.6g/ml, IC50: ~31-35g/ml), suggesting that the covalent conjugation of TP359 with SWCNTs-Ag was very effective on their counterparts. Additionally, FSWCNTs-Ag are non-toxic to the eukaryotic cells at their MIC concentrations (5-2.5g/ml) compared to SWCNTs-Ag (62.5g/ml).In conclusion, we demonstrated that covalent functionalization of SWCNTs-Ag and TP359 exhibited an additive antibacterial activity. This study described a novel approach to prepare SWCNT-Ag bio-conjugates without loss of antimicrobial activity and reduced toxicity, and this strategy will aid in the development of novel and biologically important nanomaterials.


Iannucci N.B.,University of Buenos Aires | Iannucci N.B.,Therapeutic Peptides | Ripoll G.V.,National University of Quilmes | Garona J.,National University of Quilmes | And 4 more authors.
Future Medicinal Chemistry | Year: 2011

Background: Desmopressin (dDAVP), a synthetic nonapeptide derivative of arginine vasopressin, is a safe antidiuretic and hemostatic compound that acts as a selective agonist for the vasopressin V2 membrane receptor (V2R). It is known that dDAVP can inhibit progression of residual metastatic cells in preclinical models. Among other mechanisms, the compound induces an agonist effect on V2R present in tumor cells. Results/discussion: Looking for novel analogs with improved anti-tumor activity, positions 4 and 5, at the conformational peptide loop, were substituted. The analog [V 4Q 5]dDAVP ([4-valine 5-glutamine] desmopressin) exhibited a significantly higher antiproliferative effect than dDAVP in cultures of MCF-7, a V2R-expressing human breast carcinoma cell line. The chiral isomer of this analog and tetrapeptide fragments corresponding to the loop region were also assessed. Conclusion: Preclinical evaluation of the anti-tumor activity of [V 4Q 5]dDAVP in animal models is warranted. © 2011 Future Science Ltd.


Trademark
Therapeutic Peptides | Date: 2010-04-13

Lipopeptides used in the manufacture of cosmetics.


Trademark
Therapeutic Peptides | Date: 2010-04-13

Lipopeptides used in the manufacture of cosmetics.


Trademark
Therapeutic Peptides | Date: 2010-04-13

Lipopeptides used in the manufacture of cosmetics.


Trademark
Therapeutic Peptides | Date: 2010-04-13

Lipopeptides used in the manufacture of cosmetics.


Trademark
Therapeutic Peptides | Date: 2010-04-13

Lipopeptides used in the manufacture of cosmetics.


Trademark
Therapeutic Peptides | Date: 2010-04-13

Lipopeptides used in the manufacture of cosmetics.


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