RESUMEN

Peptides that form transmembrane barrel-stave pores are potential alternative therapeutics for bacterial infections and cancer. However, their optimization for clinical translation is hampered by a lack of sequence-function understanding. Recently, we have de novo designed the first synthetic barrel-stave pore-forming antimicrobial peptide with an identified function of all residues. Here, we systematically mutate the peptide to improve pore-forming ability in anticipation of enhanced activity. Using computer simulations, supported by liposome leakage and atomic force microscopy experiments, we find that pore-forming ability, while critical, is not the limiting factor for improving activity in the submicromolar range. Affinity for bacterial and cancer cell membranes needs to be optimized simultaneously. Optimized peptides more effectively killed antibiotic-resistant ESKAPEE bacteria at submicromolar concentrations, showing low cytotoxicity to human cells and skin model. Peptides showed systemic anti-infective activity in a preclinical mouse model of Acinetobacter baumannii infection. We also demonstrate peptide optimization for pH-dependent antimicrobial and anticancer activity.

Asunto(s)

Antineoplásicos , Diseño de Fármacos , Humanos , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/síntesis química , Animales , Ratones , Pruebas de Sensibilidad Microbiana , Acinetobacter baumannii/efectos de los fármacos , Antibacterianos/farmacología , Antibacterianos/química , Antibacterianos/síntesis química , Línea Celular Tumoral , Péptidos Catiónicos Antimicrobianos/farmacología , Péptidos Catiónicos Antimicrobianos/química , Péptidos Catiónicos Antimicrobianos/síntesis química , Péptidos Antimicrobianos/química , Péptidos Antimicrobianos/farmacología , Péptidos Antimicrobianos/síntesis química

RESUMEN

The number of antibiotic-resistant microbial infections is dramatically increasing, while the discovery of new antibiotics is significantly declining. Furthermore, the activity of antibiotics is negatively influenced by the ability of bacteria to form sessile communities, called biofilms, and by the microenvironment of the infection, characterized by an acidic pH, especially in the lungs of patients suffering from cystic fibrosis (CF). Antimicrobial peptides represent interesting alternatives to conventional antibiotics, and with expanding properties. Here, we explored the effects of an acidic pH on the antimicrobial and antibiofilm activities of the AMP Esc(1-21) and we found that it slightly lost activity (from 2- to 4-fold) against the planktonic form of a panel of Gram-negative bacteria, with respect to a ≥ 32-fold of traditional antibiotics. Furthermore, it retained its activity against the sessile form of these bacteria grown in media with a neutral pH, and showed similar or higher effectiveness against the biofilm form of bacteria grown in acidic media, simulating a CF-like acidic microenvironment, compared to physiological conditions.

RESUMEN

Staphylococcus aureus, a bacterium resistant to multiple drugs, is a significant cause of illness and death worldwide. Antimicrobial peptides (AMPs) provide an excellent potential strategy to cope with this threat. Recently, we characterized a derivative of the frog-skin AMP esculentin-1a, Esc(1-21) (1) that is endowed with potent activity against Gram-negative bacteria but poor efficacy against Gram-positive strains. In this study, three analogues of peptide 1 were designed by replacing Gly8 with α-aminoisobutyric acid (Aib), Pro, and dPro (2-4, respectively). The single substitution Gly8 → Aib8 in peptide 2 makes it active against the planktonic form of Gram-positive bacterial strains, especially Staphylococcus aureus, including multidrug-resistant clinical isolates, with an improved biostability without resulting in cytotoxicity to mammalian cells. Moreover, peptide 2 showed a higher antibiofilm activity than peptide 1 against both reference and clinical isolates of S. aureus. Peptide 2 was also able to induce rapid bacterial killing, suggesting a membrane-perturbing mechanism of action. Structural analysis of the most active peptide 2 evidenced that the improved biological activity of peptide 2 is the consequence of a combination of higher biostability, higher α helical content, and ability to reduce membrane fluidity and to adopt a distorted helix, bent in correspondence of Aib8. Overall, this study has shown how a strategic single amino acid substitution is sufficient to enlarge the spectrum of activity of the original peptide 1, and improve its biological properties for therapeutic purposes, thus paving the way to optimize AMPs for the development of new broad-spectrum anti-infective agents.

Asunto(s)

Sustitución de Aminoácidos , Antibacterianos , Biopelículas , Pruebas de Sensibilidad Microbiana , Staphylococcus aureus , Biopelículas/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Antibacterianos/farmacología , Antibacterianos/química , Péptidos Antimicrobianos/farmacología , Péptidos Antimicrobianos/química , Humanos , Proteínas Anfibias/farmacología , Proteínas Anfibias/química , Proteínas Anfibias/genética , Péptidos Catiónicos Antimicrobianos/farmacología , Péptidos Catiónicos Antimicrobianos/química , Animales , Farmacorresistencia Bacteriana

RESUMEN

Antimicrobial resistance is a silent pandemic harming human health, and Pseudomonas aeruginosa is the most common bacterium responsible for chronic pulmonary and eye infections. Antimicrobial peptides (AMPs) represent promising alternatives to conventional antibiotics. In this review, the in vitro/in vivo activities of the frog skin-derived AMP Esc(1-21) are shown. Esc(1-21) rapidly kills both the planktonic and sessile forms of P. aeruginosa and stimulates migration of epithelial cells, likely favoring repair of damaged tissue. However, to undertake preclinical studies, some drawbacks of AMPs (cytotoxicity, poor biostability, and limited delivery to the target site) must be overcome. For this purpose, the stereochemistry of two amino acids of Esc(1-21) was changed to obtain the diastereomer Esc(1-21)-1c, which is more stable, less cytotoxic, and more efficient in treating P. aeruginosa-induced lung and cornea infections in mouse models. Incorporation of these peptides (Esc peptides) into nanoparticles or immobilization to a medical device (contact lens) was revealed to be an effective strategy to ameliorate and/or to prolong the peptides' antimicrobial efficacy. Overall, these data make Esc peptides encouraging candidates for novel multifunctional drugs to treat lung pathology especially in patients with cystic fibrosis and eye dysfunctions, characterized by both tissue injury and bacterial infection.

Asunto(s)

Infecciones por Pseudomonas , Pseudomonas aeruginosa , Animales , Pseudomonas aeruginosa/efectos de los fármacos , Infecciones por Pseudomonas/tratamiento farmacológico , Infecciones por Pseudomonas/microbiología , Humanos , Anuros , Piel/microbiología , Piel/efectos de los fármacos , Péptidos Antimicrobianos/farmacología , Péptidos Antimicrobianos/química , Péptidos Catiónicos Antimicrobianos/farmacología , Péptidos Catiónicos Antimicrobianos/uso terapéutico , Péptidos Catiónicos Antimicrobianos/química , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Antibacterianos/química

RESUMEN

Multidrug-resistant (MDR) pathogens are severely impacting our ability to successfully treat common infections. Here we report the synthesis of a panel of adarotene-related retinoids showing potent antimicrobial activity on Staphylococcus aureus strains (including multidrug-resistant ones). Fluorescence and molecular dynamic studies confirmed that the adarotene analogues were able to induce conformational changes and disfunctions to the cell membrane, perturbing the permeability of the phospholipid bilayer. Since the major obstacle for developing retinoids is their potential cytotoxicity, a selected candidate was further investigated to evaluate its activity on a panel of human cell lines. The compound was found to be well tolerated, with IC50 5-15-fold higher than the MIC on S. aureus strains. Furthermore, the adarotene analogue had a good pharmacokinetic profile, reaching a plasma concentration of about 6 µM after 0.5 h after administration (150 mg/kg), at least twice the MIC observed against various bacterial strains. Moreover, it was demonstrated that the compound potentiated the growth-inhibitory effect of the poorly bioavailable rifaximin, when used in combination. Overall, the collected data pave the way for the development of synthetic retinoids as potential therapeutics for hard-to-treat infectious diseases caused by antibiotic-resistant Gram-positive pathogens.

Asunto(s)

Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Humanos , Staphylococcus aureus , Antibacterianos , Retinoides/farmacología , Infecciones Estafilocócicas/tratamiento farmacológico , Pruebas de Sensibilidad Microbiana

RESUMEN

Introduction: The increase in bacterial strains resistant to conventional antibiotics is an alarming problem for human health and could lead to pandemics in the future. Among bacterial pathogens responsible for a large variety of severe infections there is Pseudomonas aeruginosa. Therefore, there is an urgent need for new molecules with antimicrobial activity or that can act as adjuvants of antibiotics already in use. In this scenario, antimicrobial peptides (AMPs) hold great promise. Recently, we characterized a frog-skin AMP derived from esculentin-1a, namely Esc(1-21)-1c, endowed with antipseudomonal activity without being cytotoxic to human cells. Methods: The combinatorial effect of the peptide and antibiotics was investigated through the checkerboard assay, differential proteomic and transcriptional analysis. Results: Here, we found that Esc(1-21)-1c can synergistically inhibit the growth of P. aeruginosa cells with three different antibiotics, including tetracycline. We therefore investigated the underlying mechanism implemented by the peptide using a differential proteomic approach. The data revealed a significant decrease in the production of three proteins belonging to the MexAB-OprM efflux pump upon treatment with sub-inhibitory concentration of Esc(1-21)-1c. Down-regulation of these proteins was confirmed by transcriptional analysis and direct measurement of their relative levels in bacterial cells by tandem mass spectrometry analysis in multiple reaction monitoring scan mode. Conclusion: These evidences suggest that treatment with Esc(1-21)-1c in combination with antibiotics would increase the intracellular drug content making bacteria more susceptible to the antibiotic. Overall, these results highlight the importance of characterizing new molecules able to synergize with conventional antibiotics, paving the way for the development of alternative therapeutic strategies based on AMP/antibiotic formulations to counteract the emergence of resistant bacterial strains and increase the use of "old" antibiotics in medical practice.

RESUMEN

The corneal epithelium is a layer in the anterior part of eye that contributes to light refraction onto the retina and to the ocular immune defense. Although an intact corneal epithelium is an excellent barrier against microbial pathogens and injuries, corneal abrasions can lead to devastating eye infections. Among them, Pseudomonas aeruginosa-associated keratitis often results in severe deterioration of the corneal tissue and even blindness. Hence, the discovery of new drugs able not only to eradicate ocular infections, which are often resistant to antibiotics, but also to elicit corneal wound repair is highly demanded. Recently, we demonstrated the potent antipseudomonal activity of two peptides, Esc(1-21) and its diastereomer Esc(1-21)-1c. In this study, by means of a mouse model of P. aeruginosa keratitis and an in vivo corneal debridement wound, we discovered the efficacy of these peptides, particularly Esc(1-21)-1c, to cure keratitis and to promote corneal wound healing. This latter property was also supported by in vitro cell scratch and ELISA assays. Overall, the current study highlights Esc peptides as novel ophthalmic agents for treating corneal infection and injury, being able to display a dual function, antimicrobial and wound healing, rarely identified in a single peptide at the same micromolar concentration range.

Asunto(s)

Lesiones de la Cornea , Queratitis , Infecciones por Pseudomonas , Animales , Ratones , Pseudomonas aeruginosa , Infecciones por Pseudomonas/tratamiento farmacológico , Infecciones por Pseudomonas/microbiología , Queratitis/tratamiento farmacológico , Queratitis/microbiología , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Antibacterianos/química , Lesiones de la Cornea/tratamiento farmacológico , Péptidos/uso terapéutico , Cicatrización de Heridas

RESUMEN

The plight of antimicrobial resistance continues to limit the availability of antibiotic treatment effective in combating resistant bacterial infections. Despite efforts made to rectify this issue and minimise its effects on both patients and the wider community, progress in this area remains minimal. Here, we de-novo designed a peptide named KDEON WK-11, building on previous work establishing effective residues and structures active in distinguished antimicrobial peptides such as lactoferrin. We assessed its antimicrobial activity against an array of bacterial strains and identified its most potent effect, against Pseudomonas aeruginosa with an MIC value of 3.12 µM, lower than its counterparts developed with similar residues and chain lengths. We then determined its anti-biofilm properties, potential mechanism of action and in vitro cytotoxicity. We identified that KDEON WK-11 had a broad range of antimicrobial activity and specific capabilities to fight Pseudomonas aeruginosa with low in vitro cytotoxicity and promising potential to express anti-lipopolysaccharide qualities, which could be exploited to expand its properties into an anti-sepsis agent.

RESUMEN

In recent years, we have discovered Esc(1-21) and its diastereomer (Esc peptides) as valuable candidates for the treatment of Pseudomonas lung infection, especially in patients with cystic fibrosis (CF). Furthermore, engineered poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) were revealed to be a promising pulmonary delivery system of antimicrobial peptides. However, the "ad hoc" development of novel therapeutics requires consideration of their stability, tolerability, and safety. Hence, by means of electrophysiology experiments and preclinical studies on healthy mice, we demonstrated that neither Esc peptides or Esc-peptide-loaded PLGA NPs significantly affect the integrity of the lung epithelium, nor change the global gene expression profile of lungs of treated animals compared to those of vehicle-treated animals. Noteworthy, the Esc diastereomer endowed with the highest antimicrobial activity did not provoke any pulmonary pro-inflammatory response, even at a concentration 15-fold higher than the efficacy dosage 24 h after administration in the free or encapsulated form. The therapeutic index was ≥70, and the peptide was found to remain available in the bronchoalveolar lavage of mice, after two days of incubation. Overall, these studies should open an avenue for a new up-and-coming pharmacological approach, likely based on inhalable peptide-loaded NPs, to address CF lung disease.

RESUMEN

Temporin family is one of the largest among antimicrobial peptides (AMPs), which act mainly by penetrating and disrupting the bacterial membranes. To further understand the relationship between the physical-chemical properties and their antimicrobial activity and selectivity, an analogue of Temporin L, [Nle1, dLeu9, dLys10]TL (Nle-Phe-Val-Pro-Trp-Phe-Lys-Phe-dLeu-dLys-Arg-Ile-Leu-CONH2) has been developed in the present work. The design strategy consisted of the addition of a norleucine residue at the N-terminus of the lead peptide sequence, [dLeu9, dLys10]TL, previously developed by our group. This modification promoted an increase of peptide hydrophobicity and, interestingly, more efficient activity against both Gram-positive and Gram-negative strains, without affecting human keratinocytes and red blood cells survival compared to the lead peptide. Thus, this novel compound was subjected to biophysical studies, which showed that the peptide [Nle1, dLeu9, dLys10]TL is unstructured in water, while it adopts ß-type conformation in liposomes mimicking bacterial membranes, in contrast to its lead peptide forming α-helical aggregates. After its aggregation in the bacterial membrane, [Nle1, dLeu9, dLys10]TL induced membrane destabilization and deformation. In addition, the increase of peptide hydrophobicity did not cause a loss of anti-inflammatory activity of the peptide [Nle1, dLeu9, dLys10]TL in comparison with its lead peptide. In this study, our results demonstrated that positive net charge, optimum hydrophobic-hydrophilic balance, and chain length remain the most important parameters to be addressed while designing small cationic AMPs.

RESUMEN

In today's post-antibiotic era, the search for new antimicrobial compounds is of major importance and nature represents one of the primary sources of bioactive molecules. In this work, through a cheminformatics approach, we clustered an in-house library of natural products and their derivatives based on a combination of fingerprints and substructure search. We identified the prenylated emodine-type anthranoid ferruginin A as a novel antimicrobial compound. We tested its ability to inhibit and kill a panel of Gram-positive and Gram-negative bacteria, and compared its activity with that of two analogues, vismione B and ferruanthrone. Furthermore, the capability of these three anthranoids to disrupt staphylococcal biofilm was investigated, as well as their effect on the viability of human keratinocytes. Ferruginin A showed a potent activity against both the planktonic and biofilm forms of Gram-positive bacteria (i.e., Staphylococcus aureus and S. epidermidis) and had the best therapeutic index compared to vismione B and ferruanthrone. In conclusion, ferruginin A represents a promising scaffold for the further development of valuable antimicrobial agents.

RESUMEN

Many antibiotics are ineffective in killing Gram-negative bacteria due to the permeability barrier of the outer-membrane LPS. Infections caused by multi-drug-resistant Gram-negative pathogens require new antibiotics, which are often difficult to develop. Antibiotic potentiators disrupt outer-membrane LPS and can assist the entry of large-scaffold antibiotics to the bacterial targets. In this work, we designed a backbone-cyclized ultra-short, six-amino-acid-long (WKRKRY) peptide, termed cWY6 from LPS binding motif of ß-boomerang bactericidal peptides. The cWY6 peptide does not exhibit any antimicrobial activity; however, it is able to permeabilize the LPS outer membrane. Our results demonstrate the antibiotic potentiator activity in the designed cWY6 peptide for several conventional antibiotics (vancomycin, rifampicin, erythromycin, novobiocin and azithromycin). Remarkably, the short cWY6 peptide exhibits wound-healing activity in in vitro assays. NMR, computational docking and biophysical studies describe the atomic-resolution structure of the peptide in complex with LPS and mode of action in disrupting the outer membrane. The dual activities of cWY6 peptide hold high promise for further translation to therapeutics.

Asunto(s)

Antibacterianos , Lipopolisacáridos , Lipopolisacáridos/metabolismo , Antibacterianos/farmacología , Antibacterianos/química , Péptidos Catiónicos Antimicrobianos/química , Azitromicina/farmacología , Rifampin/farmacología , Pruebas de Sensibilidad Microbiana , Bacterias Gramnegativas

RESUMEN

Mutations in the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) protein lead to persistent lung bacterial infections, mainly due to Pseudomonas aeruginosa, causing loss of respiratory function and finally death of people affected by CF. Unfortunately, even in the era of CFTR modulation therapies, management of pulmonary infections in CF remains highly challenging especially for patients with advanced stages of lung disease. Recently, we identified antimicrobial peptides (AMPs), namely Esc peptides, with potent antipseudomonal activity. In this study, by means of electrophysiological techniques and computational studies we discovered their ability to increase the CFTR-controlled ion currents, by direct interaction with the F508del-CFTR mutant. Remarkably, this property was not explored previously with any AMPs or peptides in general. More interestingly, in contrast with clinically used CFTR modulators, Esc peptides would give particular benefit to CF patients by combining their capability to eradicate lung infections and to act as promoters of airway wound repair with their ability to ameliorate the activity of the channel with conductance defects. Overall, our findings not only highlighted Esc peptides as the first characterized AMPs with a novel property, that is the potentiator activity of CFTR, but also paved the avenue to investigate the functions of AMPs and/or other peptide molecules, for a new up-and-coming pharmacological approach to address CF lung disease.

Asunto(s)

Péptidos Antimicrobianos/metabolismo , Péptidos Antimicrobianos/farmacología , Regulador de Conductancia de Transmembrana de Fibrosis Quística/metabolismo , Enfermedades Pulmonares/tratamiento farmacológico , Infecciones por Pseudomonas/tratamiento farmacológico , Animales , Antibacterianos/metabolismo , Antibacterianos/farmacología , Bicarbonatos/metabolismo , Cloruros/metabolismo , Fibrosis Quística/genética , Fibrosis Quística/microbiología , Regulador de Conductancia de Transmembrana de Fibrosis Quística/genética , Humanos , Transporte Iónico/efectos de los fármacos , Enfermedades Pulmonares/microbiología , Enfermedades Pulmonares/patología , Infecciones por Pseudomonas/patología , Pseudomonas aeruginosa/patogenicidad , Ratas , Ratas Endogámicas F344

RESUMEN

The pharmacodynamic and pharmacokinetic properties of bioactive peptides can be modulated by introducing conformational constraints such as intramolecular macrocyclizations, which can involve either the backbone and/or side chains. Herein, we aimed at increasing the α-helicity content of temporin L, an isoform of an intriguing class of linear antimicrobial peptides (AMPs), endowed with a wide antimicrobial spectrum, by the employment of diverse side-chain tethering strategies, including lactam, 1,4-substituted [1,2,3]-triazole, hydrocarbon, and disulfide linkers. Our approach resulted in a library of cyclic temporin L analogues that were biologically assessed for their antimicrobial, cytotoxic, and antibiofilm activities, leading to the development of the first-in-class cyclic peptide related to this AMP family. Our results allowed us to expand the knowledge regarding the relationship between the α-helical character of temporin derivatives and their biological activity, paving the way for the development of improved antibiotic cyclic AMP analogues.

Asunto(s)

Antibacterianos/farmacología , Péptidos Catiónicos Antimicrobianos/farmacología , Antineoplásicos/farmacología , Bacterias/efectos de los fármacos , Diseño de Fármacos , Animales , Antibacterianos/síntesis química , Antibacterianos/química , Péptidos Catiónicos Antimicrobianos/síntesis química , Péptidos Catiónicos Antimicrobianos/química , Antineoplásicos/síntesis química , Antineoplásicos/química , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Rana temporaria , Relación Estructura-Actividad

RESUMEN

Persistent infections, such as those provoked by the Gram-negative bacterium Pseudomonas aeruginosa in the lungs of cystic fibrosis (CF) patients, can induce inflammation with lung tissue damage and progressive alteration of respiratory function. Therefore, compounds having both antimicrobial and immunomodulatory activities are certainly of great advantage in fighting infectious diseases and chronic inflammation. We recently demonstrated the potent antipseudomonal efficacy of the antimicrobial peptide (AMP) Esc(1-21) and its diastereomer Esc(1-21)-1c, namely Esc peptides. Here, we confirmed this antimicrobial activity by reporting on the peptides' ability to kill P. aeruginosa once internalized into alveolar epithelial cells. Furthermore, by means of enzyme-linked immunosorbent assay and Western blot analyses, we investigated the peptides' ability to detoxify the bacterial lipopolysaccharide (LPS) by studying their effects on the secretion of the pro-inflammatory cytokine IL-6 as well as on the expression of cyclooxygenase-2 from macrophages activated by P. aeruginosa LPS. In addition, by a modified scratch assay we showed that both AMPs are able to stimulate the closure of a gap produced in alveolar epithelial cells when cell migration is inhibited by concentrations of Pseudomonas LPS that mimic lung infection conditions, suggesting a peptide-induced airway wound repair. Overall, these results have highlighted the two Esc peptides as valuable candidates for the development of new multifunctional therapeutics for treatment of chronic infectious disease and inflammation, as found in CF patients.

Asunto(s)

Enfermedades Transmisibles/tratamiento farmacológico , Fibrosis Quística/tratamiento farmacológico , Inflamación/tratamiento farmacológico , Proteínas Citotóxicas Formadoras de Poros/farmacología , Línea Celular , Enfermedad Crónica/prevención & control , Enfermedades Transmisibles/microbiología , Enfermedades Transmisibles/patología , Ciclooxigenasa 2/genética , Fibrosis Quística/microbiología , Fibrosis Quística/patología , Defensinas/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Factores Inmunológicos/farmacología , Inflamación/microbiología , Inflamación/patología , Interleucina-6/genética , Lipopolisacáridos/antagonistas & inhibidores , Lipopolisacáridos/química , Pulmón/efectos de los fármacos , Pulmón/microbiología , Proteínas Citotóxicas Formadoras de Poros/química , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/patogenicidad , Estereoisomerismo , Cicatrización de Heridas/efectos de los fármacos , Cicatrización de Heridas/genética

RESUMEN

Bacterial biofilms are a serious threat for human health, and the Gram-positive bacterium Staphylococcus aureus is one of the microorganisms that can easily switch from a planktonic to a sessile lifestyle, providing protection from a large variety of adverse environmental conditions. Dormant non-dividing cells with low metabolic activity, named persisters, are tolerant to antibiotic treatment and are the principal cause of recalcitrant and resistant infections, including skin infections. Antimicrobial peptides (AMPs) hold promise as new anti-infective agents to treat such infections. Here for the first time, we investigated the activity of the frog-skin AMP temporin G (TG) against preformed S. aureus biofilm including persisters, as well as its efficacy in combination with tobramycin, in inhibiting S. aureus growth. TG was found to provoke ~50 to 100% reduction of biofilm viability in the concentration range from 12.5 to 100 µM vs ATCC and clinical isolates and to be active against persister cells (about 70-80% killing at 50-100 µM). Notably, sub-inhibitory concentrations of TG in combination with tobramycin were able to significantly reduce S. aureus growth, potentiating the antibiotic power. No critical cytotoxicity was detected when TG was tested in vitro up to 100 µM against human keratinocytes, confirming its safety profile for the development of a new potential anti-infective drug, especially for treatment of bacterial skin infections.

Asunto(s)

Antibacterianos/farmacología , Péptidos Catiónicos Antimicrobianos/farmacología , Biopelículas/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Sinergismo Farmacológico , Tobramicina/farmacología

RESUMEN

The rapid development of antimicrobial resistance is pushing the search in the discovering of novel antimicrobial molecules to prevent and treat bacterial infections. Self-assembling antimicrobial peptides, as the lipidated peptides, are a novel and promising class of molecules capable of meeting this need. Based on previous work on Temporin L analogs, several new molecules lipidated at the N- or and the C-terminus were synthesised. Our goal is to improve membrane interactions through finely tuning self-assembly to reduce oligomerisation in aqueous solution and enhance self-assembly in bacterial membranes while reducing toxicity against human cells. The results here reported show that the length of the aliphatic moiety is a key factor to control target cell specificity and the oligomeric state of peptides either in aqueous solution or in a membrane-mimicking environment. The results of this study pave the way for the design of novel molecules with enhanced activities.

Asunto(s)

Antibacterianos/farmacología , Péptidos Catiónicos Antimicrobianos/farmacología , Klebsiella pneumoniae/efectos de los fármacos , Pseudomonas aeruginosa/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Animales , Antibacterianos/síntesis química , Antibacterianos/química , Péptidos Catiónicos Antimicrobianos/síntesis química , Péptidos Catiónicos Antimicrobianos/química , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Relación Dosis-Respuesta a Droga , Humanos , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Proteolisis/efectos de los fármacos , Ovinos , Relación Estructura-Actividad

RESUMEN

Colistin is a last-resort antibiotic for the treatment of multidrug resistant Gram-negative bacterial infections. Recently, a natural ent-beyerene diterpene was identified as a promising inhibitor of the enzyme responsible for colistin resistance mediated by lipid A aminoarabinosylation in Gram-negative bacteria, namely, ArnT (undecaprenyl phosphate-alpha-4-amino-4-deoxy-l-arabinose arabinosyl transferase). Here, semisynthetic analogues of hit were designed, synthetized, and tested against colistin-resistant Pseudomonas aeruginosa strains including clinical isolates to exploit the versatility of the diterpene scaffold. Microbiological assays coupled with molecular modeling indicated that for a more efficient colistin adjuvant activity, likely resulting from inhibition of the ArnT activity by the selected compounds and therefore from their interaction with the catalytic site of ArnT, an ent-beyerane scaffold is required along with an oxalate-like group at C-18/C-19 or a sugar residue at C-19 to resemble L-Ara4N. The ent-beyerane skeleton is identified for the first time as a privileged scaffold for further cost-effective development of valuable colistin resistance inhibitors.

Asunto(s)

Colistina , Diterpenos , Antibacterianos/farmacología , Proteínas Bacterianas , Diterpenos/farmacología , Farmacorresistencia Bacteriana , Pruebas de Sensibilidad Microbiana , Pseudomonas aeruginosa

RESUMEN

Antibiotic resistance is now considered a worldwide problem that puts public health at risk. The onset of bacterial strains resistant to conventional antibiotics and the scarcity of new drugs have prompted scientific research to re-evaluate natural products as molecules with high biological and chemical potential. A class of natural compounds of significant importance is represented by alkaloids derived from higher plants. In this review, we have collected data obtained from various research groups on the antimicrobial activities of these alkaloids against conventional antibiotic-resistant strains. In addition, the structure-function relationship was described and commented on, highlighting the high potential of alkaloids as antimicrobials.

Asunto(s)

Alcaloides/farmacología , Antibacterianos/farmacología , Productos Biológicos/farmacología , Farmacorresistencia Microbiana/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Extractos Vegetales/farmacología , Infecciones Estafilocócicas/tratamiento farmacológico , Humanos , Infecciones Estafilocócicas/microbiología