Promising antibiofilm activity of peptidomimetics

Pathogenic biofilms are a global health care concern, as they can cause extensive antibiotic resistance, morbidity, mortality, and thereby substantial economic loss. Scientific efforts have been made over the past few decades, but so far there is no effective treatment targeting the bacteria in biofilms. Antimicrobial peptidomimetics have been proposed as promising potential anti-biofilm agents. Indeed, these structurally enhanced molecules can mimic the action of peptides but are not susceptible to proteolysis or immunogenicity, the characteristic limitations of natural peptides. Here, we provide insights into antibiofilm peptidomimetic strategies and molecular targets, and discuss the design of two major peptidomimetics classes: AApeptides (N-acylated-N-aminoethyl-substituted peptides) and peptoids (N-substituted glycine units). In particular, we present details of their structural diversity and discuss the possible improvements that can be implemented in order to develop antibiofilm drug alternatives

Simple method for simultaneous quantification of two new derivatives of betulinic and ursolic acids with antimalarial activity by RP-HPLC-UV-CAD

Endemic in more than 90 countries and territories, malaria is the most widely, populational, and geographically, parasitic disease in the world. Plasmodium sp. resistance to available drugs is one of the biggest problems for malaria eradication. In this study, we develop a method for the simultaneous determination of two new derivatives of betulinic and ursolic acids with antimalarial activity designated 3-O-butanoylbetulinic and 3-O-butanoylursolic acids. An analytical method was developed by high-performance liquid chromatography coupled, in series, to ultraviolet (UV) and charged aerosol (CAD) detectors. The chromatographic system, operated isocratically by reversed-phase, consisted in a mobile phase composed of acetonitrile: water pH 3.0 adjusted with formic acid (85:15, v/v), flow rate of 1.2 mL/min and a PhenoSphere Next octadecylsilane column (250 mm x 4.6 mm, 5 μm particle size). Chromatograms were recorded simultaneously in UV and CAD, at a concentration of 50 µg mL-1, an injection volume of 20 μL at a controlled temperature of 50 °C. The method was found to be selective, linear (r > 0.99), precise (RSD < 2.0%), accurate, and robust for both analytes, and considered statistically validated, and can be applied to the identification and quantification of these new drug candidates

Promising Antibiofilm Activity of Peptidomimetics

Pathogenic biofilms are a global health care concern, as they can cause extensive antibiotic resistance, morbidity, mortality, and thereby substantial economic loss. Scientific efforts have been made over the past few decades, but so far there is no effective treatment targeting the bacteria in biofilms. Antimicrobial peptidomimetics have been proposed as promising potential anti-biofilm agents. Indeed, these structurally enhanced molecules can mimic the action of peptides but are not susceptible to proteolysis or immunogenicity, the characteristic limitations of natural peptides. Here, we provide insights into antibiofilm peptidomimetic strategies and molecular targets, and discuss the design of two major peptidomimetics classes: AApeptides (N-acylated-N-aminoethyl-substituted peptides) and peptoids (N-substituted glycine units). In particular, we present details of their structural diversity and discuss the possible improvements that can be implemented in order to develop antibiofilm drug alternatives

Betulinic acid-brosimine B hybrid compound has a synergistic effect with imatinib in chronic myeloid leukemia cell line, modulating apoptosis and autophagy

Chronic myeloid leukemia (CML) is a myeloproliferative disease characterized by the formation of the BCR-ABL (breakpoint cluster region-Abelson) oncoprotein. As many patients display therapeutic resistance, the development of new drugs based on semisynthetic products represents a new potential therapeutic approach for treating the disease. In this study, we investigated the cytotoxic activity, possible mechanism of action of a hybrid compound of betulinic acid (BA) and brosimine B in CML cell lines that are sensitive (K-562) and resistant (K-562R) to imatinib, in addition to evaluating lower doses of imatinib in combination with the hybrid compound. The effects of the compound, and its combination with imatinib, on apoptosis, cell cycle, autophagy and oxidative stress were determined. The compound was cytotoxic in K-562 (23.57 2.87 M) and K-562R (25.80 3.21 M) cells, and a synergistic effect was observed when it was associated with imatinib. Apoptosis was mediated by the caspase 3 and 9 intrinsic pathway, and cell cycle evaluation showed arrest at G0/G1. In addition, the hybrid compound increased the production of reactive oxygen species and induced autophagy by increasing LC3II and Beclin-1 mRNA levels. Results suggest that this hybrid compound causes the death of both imatinib-sensitive and -resistant cell lines and may hold potential as a new anticancer treatment against CML

Capsicumicine, a new bioinspired peptide from red peppers prevents staphylococcal biofilm in vitro and in vivo via a matrix anti-assembly mechanism of action

Staphylococci are pathogenic biofilm-forming bacteria and a source of multidrug resistance and/or tolerance causing a broad spectrum of infections. These bacteria are enclosed in a matrix that allows them to colonize medical devices, such as catheters and tissues, and that protects against antibiotics and immune systems. Advances in antibiofilm strategies for targeting this matrix are therefore extremely relevant. Here, we describe the development of the Capsicum pepper bioinspired peptide “capsicumicine.” By using microbiological, microscopic, and nuclear magnetic resonance (NMR) approaches, we demonstrate that capsicumicine strongly prevents methicillin-resistant Staphylococcus epidermidis biofilm via an extracellular “matrix anti-assembly” mechanism of action. The results were confirmed in vivo in a translational preclinical model that mimics medical device-related infection. Since capsicumicine is not cytotoxic, it is a promising candidate for complementary treatment of infectious diseases

Red pepper peptide coatings control Staphylococcus epidermidis adhesion and biofilm formation

Medical devices (indwelling) have greatly improved healthcare. Nevertheless, infections related to the use of these apparatuses continue to be a major clinical concern. Biofilms form on surfaces after bacterial adhesion, and they function as bacterial reservoirs and as resistance and tolerance factors against antibiotics and the host immune response. Technological strategies to control biofilms and bacterial adhesion, such as the use of surface coatings, are being explored more frequently, and natural peptides may promote their development. In this study, we purified and identified antibiofilm peptides from Capsicum baccatum (red pepper) using chromatography- tandem mass spectrometry, MALDI-MS, MS/MS and bioinformatics. These peptides strongly controlled biofilm formation by Staphylococcus epidermidis, the most prevalent pathogen in device-related infections, without any antibiotic activity. Furthermore, natural peptide-coated surfaces dislayed effective antiadhesive proprieties and showed no cytotoxic effects against different representative human cell lines. Finally, we determined the lead peptide predicted by Mascot and identified CSP37, which may be useful as a prime structure for the design of new antibiofilm agents. Together, these results shed light on natural Capsicum peptides as a possible antiadhesive coat to prevent medical device colonization

Reações de cicloadição : uma abordagem teórica e aplicações em síntese orgânica

Este artigo aborda os principais aspectos teóricos das reações de cicloadição, considerando a teoria de orbitais moleculares e a teoria de perturbações. Além disso, as reações de Diels-Alder e as reações 1,3-dipolares (cicloadições térmicas [4+2]) são detalhadas e exemplos de aplicações dessas reações são apresentados.This review reports the theoretical approach of the main aspects of cycloaddition reactions, considering the molecular orbital and perturbation theories. Moreover, Diels-Alder and 1,3-dipolar reactions (thermal [4+2] cycloadditions) are detailed and some examples of their application are described

Conception et synthèse de nouveaux dérivés de génines triterpéniques d’Ilex à visée antipaludique

A Malária é uma doença endêmica que representa um grave problema de saúde pública na África, Ásia, Oceania e América Latina. Na América latina as principais áreas endêmicas estão na Bacia Amazônica e, infelizmente, são registrados cem mil novos casos clínicos no Brasil anualmente. Atualmente, mesmo nos Estados Unidos e no Oeste da Europa, o número de casos de malária tem aumentado a cada ano devido aos viajantes que vêm de áreas de risco. Este trabalho apresenta a síntese de compostos visando aumentar a atividade antimalárica de triterpenos através de farmacomodulação, especialmente em C-3 e em C-28 dos ácidos ursólico e oleanólico. Sete produtos naturais foram obtidos a partir das espécies sul-americanas Ilex paraguariensis e Ilex dumosa: os triterpenos ácido ursólico e ácido oleanólico e as matessaponinas 1 e 3, bem como, os derivados peracetilados das matessaponinas 1, 2 e 3. Três séries de derivados triterpênicos foram sintetizadas: derivados dos ácidos ursólico e oleanólico com modificações no ciclo A, derivados ferrocênicos e derivados piperazínicos do ácido ursólico. Estes compostos foram testados in vitro frente a cepas de Plasmodium falciparum. Os derivados piperazínicos do ácido ursólico foram os mais ativos. Sete novos análogos apresentaram atividade em concentrações na ordem de nanomolar (IC50 78 a 964 nM), enquanto que a cloroquina apresentou IC50 de 130 nM. Baixos índices de resistência cruzada com a cloroquina foram observados. Este estudo também contribuiu para o melhor entendimento da relação estrutura-atividade (REA) para a classe de derivados piperazínicos do ácido ursólico. Desta forma, foi demonstrada a importância do esqueleto triterpênico e do grupamento acetila em C-3 para a atividade antimalárica. O grupamento piperazina foi identificado como farmacóforo nesta série de compostos. Foi caracterizada a importância de substituintes hidrofílicos no nitrogênio terminal da cadeia lateral bis-(3-aminopropil)piperazina através de um estudo de relação estrutura-atividade quantitativa (QSAR). O possível mecanismo de ação destes compostos foi sugerido via inibição da formação de β-hematina a partir de testes in vitro e de modelagem molecular.Le paludisme est une maladie endémique sérieuse qui représente une menace importante de santé publique en Afrique, en Asie, Océanie, et en Amérique latine. En Amérique latine, les régions touchées sont principalement centrées autour de l'Amazonie brésilienne. En effet, le Brésil enregistre, chaque année, 100 000 nouveaux cas de paludisme. Aujourd’hui, même les Etats-Unis et l’Europe de l'ouest, qui ne sont pourtant pas des secteurs endémiques, enregistrent un nombre important et croissant de nouveaux cas, essentiellement dus à des voyageurs. Il y a également une recrudescence de la résistance du parasite, à l’origine du paludisme, aux molécules actuellement commercialisés. Par conséquent, la recherche de nouvelles molécules antipaludiques est un enjeu primordial. Nous avons observé que l’acide ursolique, extrait d’espèces sud americainnes Ilex paraguariensis et Ilex dumosa, possédait une activité antipaludique intéressante. Ce travail de thèse a pour but l’extraction, l’hémisynthèse d’analogues de l’acide ursolique et enfin l’évaluation de l’activité antipaludique des composés ainsi obtenus. Le but de ce travail est d'augmenter l'activité antipaludique de l’acide ursolique, initialement décrite, par pharmacomodulation du noyau triterpénique en position 3 et 28. Sept produits naturels ont été extraits et purifiés à partir d’espèces sud americainnes Ilex paraguariensis et Ilex dumosa. Il s’agit des triterpénes de l’acide ursolique et de l’acide oléanolique et les saponosides matésaponines peracetylées ou non. L’optimisation de l’activité antipaludique, par la synthèse de nouveaux analogues triterpéniques, a été basée sur l’hypothèse que l’activité antipaludique initialement observée était due à un mécanisme d’inhibition de la formation de la β-hémozoïne par l’acide ursolique. Ces analogues peuvent être classés selon trois séries : acides ursolique et oléanolique avec des modifications au niveau du cycle A, dérivés ferrocéniques de l'acide ursolique et dérivés pipéraziniques de l'acide ursolique. Les meilleures activités ont été observées pour les derivés pipéraziniques de l’acide ursolique. En effet, sept nouveaux analogues ont démontré des activités intéressantes de l'ordre de nanomolaire (IC50 78 to 964 nM). Les activités obtenues représentent ainsi un gain d’activité au moins d’un facteur 100 par rapport à celle de l’acide ursolique. Une étude de structure-activité a été réalisée sur ces dérivés pipéraziniques de l'acide ursolique. Ainsi, nous avons démontré l’importance du noyau triterpénique et du groupement acétyle en C-3 pour l’activité antipaludique. De même, l’importance des substitutions au niveau de l’azote terminal de la chaine bis-(3-aminopropyl)pipérazine, notamment de groupements hydrophiles, a aussi été réalisée par une étude de relation structure acivité quantitative (QSAR). Enfin, l’hypothèse que ces composés agissent sur l’inhibition de la formation de β-hémazoïne a été confirmée par des études in vitro (inhibition de la formation de la β-hématine) et de modélisation moléculaire