Synthesis and Biological Studies of New Temporin A Analogs Containing Unnatural Amino Acids in Position 7

(1) Background: Antimicrobial resistance is growing at an extreme pace and has proven to be an urgent topic, for research into alternative treatments. Such a prospective possibility is hidden in antimicrobial peptides because of their low to no toxicity, effectiveness at low concentrations, and most importantly their ability to be used for multiple treatments. This work was focused on the study of the effect of the modification in position 7 of Temporin A on its biological activity; (2) Methods: The targeted peptides were synthesized using Fmoc/Ot-Bu SPPS. The antibacterial activity of the analogs was determined using the broth microdilution method and disk-diffusion method. In vitro tests were performed to determine the cytotoxicity, phototoxicity, and antiproliferative activity of the peptide analogs on a panel of tumor and normal cell lines; (3) Results: All analogs except DTCit showed good antibacterial activity, with DTDab having the best activity according to the disk-diffusion method. However, DTCit had an acceptable cytotoxicity, combined with good selectivity against the test MCF-7 cell line; (4) Conclusions: The obtained results revealed the importance of the basicity and length of the side chain at position 7 in the Temporin A sequence for both tested activities

Directaccess to new β-d-galactofuranoconjugates: application to the synthesis of galactofuranosyl-l-cysteine and l-serine

International audienceGalactofuranose post-translational modifications, although quite rare, were detected in some biomolecules produced by parasites. While hexopyranosides were already linked to various peptides and proteins, few hexofuranosides have been artificially conjugated to amino acids. We thus report herein a robust glycosylation methodology to obtain S-alkyl, O-serine and S-cysteine-β-d-galactofuranosides starting from readily available galactofuranose donors. O-Acetyl, thioimidoyl and acetimidoyl donors were compared in terms of yields and selectivity when reacted with mercaptans, l-cysteine and l-serine. Acetimidates turned out to be the best notably for amino acids glycosylation

Antimicrobial activity of (KLAKLAK)–NH2 analogs against pathogenic microbial strains

Many microorganisms pose a threat to human health due to the ever-increasing bacterial resistance to conventional drugs. Nowadays, searching for new alternatives to conventional antibiotics to fight bacterial resistance is a main task. Thus, natural molecules such as amino acids and peptides arise as possible solutions to the problem. The antimicrobial activity of targeted compounds was studied by the agar-diffusion method, using the prepared working solutions of the targeted peptides with the corresponding concentrations. The results of the antimicrobial activity against different test pathogens show specificity, as antimicrobial activity against the used test microorganisms was not found in the investigated short-chain synthetic peptides Si6, Si3 and Si13. Antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, Propionibacterium acnes, Escherichia coli, Pseudomonas aeruginosa, and the yeasts Malassezia furfur and Candida albicans was established for the long-chain synthetic peptides Si1, Si5 and Si16, except Si5 which does not show activity against pathogenic fungal strain C. albicans. The compound Si16 where natural Leu in (KLAKLAK)2-NH2 is replaced by unnatural Nle is the best candidate for medical drug due to the combined antibacterial and antiproliferative effect as well as long hydrolytic stability

Synthèse et caractérisation de nouveaux précurseurs à base de N-alkyl/aryl Acrylamide pour l'élaboration de matériaux hybrides

Le Poly N-IsoPropylAcrylaMide (pNIPAM) est un polymère organique connu pour ses propriétés de biocompatibilité et de thermoréversibilité. On le retrouve donc dans l'élaboration de matériaux permettant l''encapsulation de biomolécules. Il est même utilisé pour créer des matériaux hybrides organiques-inorganiques réalisés par le procédé sol-gel. Pour essayer de modifier ses propriétés spécifiques des N-dérivés du précurseur monomérique NIPAM ont été synthétisés avec des groupements plus encombrés. Plusieurs méthodes de synthèse menées en phase aqueuse, pour des soucis de biocompatibité, ont été explorées en vue d'améliorer la pureté et le rendement des précurseurs. Des analyses par spectrométrie Infrarouge et RMN (1H et 13C) ont été effectuées pour vérifier la pureté des différents produits. Les monomères ainsi obtenus ont été polymérisés et l'évolution des propriétés mécaniques (élasticité et viscosité) du matériau obtenu ont été déterminés. Cette évolution a été suivie en temps réel par une technique non destructive développée au laboratoire. Cette technique ultrasonore utilise les propriétés classiques de la propagation d'une onde acoustique dans un volume. La comparaison des modules élastiques (G') et visqueux (G") pour ces différents matériaux permet alors de corréler la nature du groupement avec les propriétés et la structure des polymères obtenus. Les propriétés thermiques de ces matériaux ont été déterminés par des analyses calorimétriques (DSC, ATD). Par la suite des précurseurs de matériaux hybrides organiques inorganiques ont été synthétisés en créant une liaison covalente entre un précurseur de polymère organique et un alcoxyde de silicium trifonctionnel du type 2HN(CH2)nSi(OR)3. Ces différents matériaux synthétisés ont permis d'envisager l'élaboration de matériaux hybrides organiques-inorganiques dont le but est d'obtenir de nouvelles matrices pouvant encapsuler des molécules biologiquement actives tout en conservant leur activité biologique. La partie inorganique du matériau renforce les propriétés mécaniques du matériau final par rapport à un matériau purement organique

Development and validation of HPLC-DAD methodology for simultaneous qualitative and quantitative determination of thirteen substances with a steroid structure

AbstractUsing supplements in different sports is a common practice for many athletes. Unfortunately, the growth of this market has entailed some speculations, such as the addition of excessive doses of potentially toxic ingredients. Sometimes the doses listed on the package do not correspond to the real content. Some nutritional supplements on sale may contain undeclared ingredients. Some of those supplements are prohibited substances according to different regulations. Herein, a simple HPLC/DAD procedure that is easy to apply in conventional laboratory practice was developed for the simultaneous determination of 13 substances with steroid structure in nutritional supplements for sport: testosterone, testosterone propionate, testosterone enanthate, methyltestosterone, nandrolone, nandrolone propionate, nandrolone decanoate, methandienone, androstenedione, trenbolone, trenbolone acetate, trenbolone enanthate and boldenone undecylenate. The methodology includes gradient elution with mobile phase A: MeOH:ddH2O (55:45) and mobile phase B: 100% MeOH in a standard HPLC system containing a Halo 90 Å, C18 (150 x 4.6 mm, 2.7 µm) column, flow rate 0.6 mL/min, UV wavelength of 254 nm, temperature of 40 °C and 20 μL injection volume. The developed methodology was validated according to the corresponding official documents. The key parameters used for the selection of the optimal HPLC conditions were the ability of the mobile phase and solvents to be used with both an HPLC/MS and a GC/MS chromatographic system. The obtained total run time, the reproducibility of the retention times, the separation of all peaks and peak characteristics meet all requirements

Interaction of KLAKLAK-NH₂ and Analogs with Biomimetic Membrane Models

Background: Specifically designed peptide mimetics offer higher selectivity regarding their toxicity to mammalian cells. In addition to the α-helix conformation, the specific activity is related to the peptide’s ability to penetrate the cell membrane. The alterations in lipid membrane properties were addressed in the presence of the peptide KLAKLAK-NH2 and analogs containing β-alanine, strengthening the antibacterial activity and/or naphtalimide with proven anticancer properties. Methods: The molecular interactions of the peptide mimetics with POPC bilayers were studied using FTIR-ATR spectroscopy. The thermal shape fluctuation analysis of quasispherical unilamellar vesicles was applied to probe the membrane bending elasticity. The impedance characteristics of bilayer lipid membranes were measured using fast Fourier-transform electrochemical impedance spectroscopy. Results: A lateral peptide association with the membrane is reported for β-alanine-containing peptides. The most pronounced membrane softening is found for the NphtG-KLβAKLβAK-NH2 analog containing both active groups that corroborate with the indications for 1,8-naphthalimide penetration in the lipid hydrophobic area obtained from the FTIR-ATR spectra analysis. The β-alanine substitution induces strong membrane-rigidifying properties even at very low concentrations of both β-alanine-containing peptides. Conclusions: The reported results are expected to advance the progress in tailoring the pharmacokinetic properties of antimicrobial peptides with strengthened stability towards enzymatic degradation. The investigation of the nonspecific interactions of peptides with model lipid membranes is featured as a useful tool to assess the antitumor and antimicrobial potential of new peptide mimetics

Synthesis, Antiproliferative Effect and In Silico LogP Prediction of BIM-23052 Analogs Containing Tyr Instead of Phe

(1) Background: Hydrophobicity (or lipophilicity) is a limiting factor in the ability of molecules to pass through cell membranes and to perform their function. The ability to efficiently access cytosol is especially important when a synthetic compound has the potential to become a drug substance. D-Phe-Phe-Phe-D-Trp-Lys-Thr-Phe-Thr-NH2 (BIM-23052) is a linear analog of somatostatin with established in vitro GH-inhibitory activity in nanomolar (nm) concentrations and high affinity to different somatostatin receptors. (2) Methods: Series of analogs of BIM-23052 were synthesized where Phe residue(s) in the BIM-23052 molecule were replaced with Tyr using standard SPPS, Fmoc/t-Bu strategy. Analyses of target compounds were performed using HPLC/MS technique. Toxicity and antiproliferative activity were studied using in vitro NRU and MTT assays. The values of logP (partition coefficient in octanol/water) for BIM-23052 and its analogs were calculated. (3) Results: The obtained data show the best antiproliferative effect against studied cancer cells for compound D-Phe-Phe-Phe-D-Trp-Lys-Thr-Tyr7-Thr-NH2 (DD8), the most lipophilic compound according to the predicted logP values. (4) Conclusions: Multiple analyses of the obtained data reveal that compound D-Phe-Phe-Phe-D-Trp-Lys-Thr-Tyr7-Thr-NH2 (DD8) where one Phe is replaced by Tyr has the best combination of cytotoxicity, antiproliferative effect and hydrolytic stability

Synthesis, In Silico Log<i>p</i> Study, and In Vitro Analgesic Activity of Analogs of Tetrapeptide FELL

Background: The inflammatory process represents a specific response of the organism’s immune system. More often, it is related to the rising pain in the affected area. Independently of its origin, pain represents a complex and multidimensional acute or chronic subjective unpleasant perception. Currently, medical doctors prescribe various analgesics for pain treatment, but unfortunately, many of them have adverse effects or are not strong enough to suppress the pain. Thus, the search for new pain-relieving medical drugs continues. Methods: New tetrapeptide analogs of FELL with a generaanalgesic-Glu-X3-X4-Z, where X = Nle, Ile, or Val and Z = NH2 or COOH, containing different hydrophobic amino acids at positions 3 and 4, were synthesized by means of standard solid-phase peptide synthesis using the Fmoc/OtBu strategy in order to study the influence of structure and hydrophobicity on the analgesic activity. The purity of all compounds was monitored by HPLC, and their structures were proven by ESI-MS. Logp values (partition coefficient in octanol/water) for FELL analogs were calculated. Analgesic activity was examined by the Paw-pressure test (Randall-Selitto test). Results: The obtained results reveal that Leu is the best choice as a hydrophobic amino acid in the FELL structure. Conclusions: The best analgesic activity is found in the parent compound FELL and its C-terminal amide analog

Titan Based Hybrid Organic-Inorganic Gels Comprising Carbohydrate Moiety

International audienceA series of titanium based gels comprising carbohydrate moieties was synthesized. The sugars used include a specific hydrazide group as complex forming agent. Additionally, this group forms stable hydrates which allow further slow water release. As a result, the compounds used in this study form transparent and stable gels with titanium alkoxide without addition of external water. Interpretation of the IR-spectra reveals that some compounds form monodentate ligands and other bidentate ligands. Further Tian-Calvet calorimetric measurements confirmed our IR-based conclusions. This strategy of synthesis gives a new opportunity to obtain hybrid materials by addition of natural chelating ligands to slow down the hydrolysis/condensation reactions that occur during the sol-gel process. Therefore, carbohydrate moieties have been incorporated in the gels obtained and different type of Ti coordination was proposed based on the IR spectroscopy studies. SEM investigations show the influence of the ligand on the morphology of the xerogel. GRAPHICAL ABSTRAC