<p><b>Part I: Design of a Photolabile Backbone Amide Linker for the Synthesis of C-terminally Modified Peptides</b></p> <p>A new photolabile backbone amide linker has been developed for the on-resin synthesis of cyclic and C-terminally modified peptides. The linker (Hcnb) is stable to strongly acidic conditions and instead releases the completed peptide through photolytic cleavage at 365 nm. Hcnb possesses four degrees of orthogonality and is amenable to the preparation of cyclic peptides, C-terminally modified peptides, and fully protected peptides due to its photolabile backbone amide linkage. The Hcnb precursor can be conveniently synthesized in 4 steps from commercially available 4-methyl-3,5-dinitrobenzoic acid. The C-terminal amino acid residue is loaded via reductive amination of the precursor followed by an O→N transacylation for the addition of the second residue in quantitative yields, even when employing sterically bulky residues. Standard Fmoc- or Boc-based synthesis can then be utilized to complete the desired peptide. Hcnb has been used to demonstrate the linear synthesis and subsequent on-resin cyclization of various cyclic peptides of interest, as well as synthesis of C-terminal thioesters on-resin. </p> <p><b>Part II: Development of II-HMG CoA Reductase Inhibitors for use as Gram-Positive Selective Antimicrobials. </b></p> <p>Bacterial resistance to antibiotic drugs is an issue that humans have faced since the first use of sulfa drugs in the 1930s. In recent years, the rate of production of new antimicrobial drugs has diminished, as they are no longer financially beneficial to pharmaceutical companies due to short term use and rapid resistance development. This places the burden of the development of new antimicrobial drug on the academic research field. In the work presented here, progress has been made toward the development of a novel class of antimicrobial compounds. These small molecule inhibitors target II-HMG CoA Reductase, a key enzyme involved in cell wall synthesis in gram-positive bacteria. Based on analysis of co-crystal structures obtained from first- and second- generation inhibitors, structural alterations were made to design a new generation of compounds. Efforts have also been made toward identification of a potential secondary target of these inhibitors. </p>

A limited number of drug targets can be exploited by conventional drug-like compounds as the vast majority of disease-associated targets are involved in protein-protein interactions (PPI). PPI targets possess binding surfaces that lack a well-defined hydrophobic pocket amenable for binding to small drug-like compounds. A new class of therapeutics that has shown great potential at modulating PPI are macrocyclic peptides, particularly for their ability to bind to large and topologically complex protein surfaces as well as their potential to access intracellular targets. However, the efficiency of macrocyclic peptides at mediating PPIs and permeating cell membranes is conformation dependent. Here, I describe the role of peptide conformation on target recognition using three clinically relevant PPI targets: the Kelch like ECH Associated Protein-1 (KEAP1), (Chapter Two and Chapter Three); the RET receptor tyrosine kinase (Chapter Four); and β-catenin (Chapter Five). Guided by published X-ray crystal structures, peptides derived from PPI epitopes were designed and structurally constrained to mimic the conformation of the natural PPI recognition motif. In Chapter Two, I report the development of a cyclic heptapeptide derived from the transcription factor Nuclear Factor (Erythroid-derived 2)-Like 2 (Nrf2) with similar affinity for KEAP1 as native Nrf2 through conformational optimization of a linear Nrf2-derived heptapeptide. Efforts to improve the potency and physicochemical properties of the cyclic heptapeptide are discussed in Chapter Three. In Chapter Four, I describe the design of dimeric peptides as tool compounds to investigate the mechanism by which the interaction between glial cell-line derived neurotrophic factor family ligands (GFLs) and GPI-linked co-receptors, GFRα, induce RET signaling. These peptides were derived from the β-sheet regions of GFLs, GDNF and ART, that interact with GFRα1 and GFRα3, respectively. Peptide cyclization and the introduction of a β-turn promoting motif yielded GFL mimetic peptides with stronger affinity for GFRα. Lastly, Chapter Five focuses on exploring the scope of i, i+4 carbamate and amino-staples as a novel peptide stapling system to stabilize α-helical peptides. An axin-derived α-helical peptide that disrupts the β-catenin/TCF4 interaction was used as a model to determine the effect of peptide α-helical stabilization on binding affinity for β-catenin. / 2023-07-07T00:00:00Z

Thesis advisor: Jianmin Gao / Covalent drugs present a unique situation in the clinical world. Formation of a covalent bond between a drug molecule and its target protein can lead to significant increases in a number of desirable traits such as residence time, potency, and efficacy of a drug. From a kinetic perspective, the formation of a covalent bond between a drug and its target functionally eliminates the dissociation rate (koff) of the compound, ensuring that the compound will stay engaged with its target. However, development of covalent drugs has been met with caution and concern, as an irreversible covalent bond forming on the wrong target can have disastrous results, so specificity is of the utmost importance. One option for increasing specificity is by linking a covalent binding electrophile, or warhead, to a peptide. Peptide-based therapeutics have already been shown to serve as effective protein-targeting modalities with high specificity, a specificity that would greatly benefit covalent drugs. Phage display is a powerful technique for the discovery of selective peptides which utilizes the screening of vast libraries of randomized peptides to identify strong binders. This technology has been used to discover a large number of protein-targeting peptides, but also a smaller number of cyclic, covalent binding peptides that function as enzymatic inhibitors. Herein, this study aimed to explore the idea of adding covalent-binding functionality to phage libraries in novel ways and expand upon the scope of proteins that can be targeted with phage libraries containing covalent libraries. We sought to develop a mechanistic and chemical understanding of the interactions between bacteriophage and chemical warheads to best understand both the limits and the potential of this technology. In order to best understand the relationship between chemical warhead and phage particle, a model system was developed based on the M13KE pIII protein. It was found that the extracellular N-terminal domains of this protein could be expressed and purified in low yields in bacterial cells and that these domains would behave similarly in solution as in the membrane of the M13KE bacteriophage. With this protein in hand, experiments previously performed using small, cysteine containing peptides, could be performed on a full protein to mimic the phage labeling environment. This protein was used to identify efficient cysteine crosslinkers, most notably dichloroacetone (DCA) and bis-chlorooxime (BCO). The pIII protein system was then used to study the viability of bifunctional warhead molecules containing a covalent warhead and a cysteine crosslinker. Based on preliminary analyses with the pIII protein, aryl sulfonyl fluoride was chosen as a novel warhead candidate that warranted further pursuit. Kinetic NMR studies verified that aryl sulfonyl fluoride was capable of forming covalent bonds with phenols under phage labeling conditions. Labeling experiments analyzed with LC/MS seemed to indicate a degradation of the warhead. However, as the source of the degradation was not able to be determined, it was decided that various affinity assays would be used to identify if phage could be labeled with an aryl sulfonyl fluoride-DCA conjugate. Both streptavidin-bead pulldown assays and ELISA assays were used, however both assays yielded results that could not conclusively verify the integrity of the warhead. During phage labeling experiments, a phenomenon was noted that phage titers after modification showed a 2-3 order of magnitude drop in phage count. Covalent modification of phage beyond what is intended could have troubling consequences for all covalent phage libraries, and so a more in-depth approach was taken to identify and better understand phage toxicity as it relates to covalent warheads. As a model, a well-studied diazaborine-mediated warhead with a slow dissociation rate was selected and used in a range of phage toxicity screenings. Despite statistical fluctuations between trials, toxicity screenings using this warhead served to highlight a unique concern for bifunctional covalent warheads. A concentration-dependent toxicity can be seen in phage incubated with bifunctional small molecules that is not present when incubated with the monofunctional equivalents. The presence of this toxicity even towards a phage with no free thiols highlights a unique challenge of off-target labeling within phage particles that, if solved, could provide the next significant step towards developing novel covalent phage libraries. / Thesis (MS) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

O uso de peptídeos na terapêutica apresenta inúmeras limitações, desde características físico-químicas até perfil farmacocinético inadequado para absorção oral. Entretanto, novas estratégias sintéticas para redução de custos e aumento da estabilidade química e metabólica de peptídeos, associada a vias alternativas de administração foram desenvolvidas e permitiram o acesso a essas moléculas no mercado farmacêutico. Diante disso, peptídeos naturais bioativos, subexplorados do ponto de vista químico medicinal, são considerados bons protótipos para o desenvolvimento de biblioteca de análogos não-naturais, gerando informações relevantes para a compreensão da relação entre a estrutura química e a atividade biológica destes compostos. No presente estudo, os peptídeos cíclicos rufomicina B (tuberculostático), chaiyaphumine A (anti-malárico), ciclozantoxilano A e desotamide B (antibiótico) foram estudados do ponto de vista sintético sob diferentes metodologias. Para tal, os aminoácidos Fmoc-N-Metil-L-Leucina e Fmoc-L-crotil-glicina foram sintetizados com rendimentos satisfatórios para síntese do antibiótico rufomicina B. O aminoácido Fenil-acetil-L-treonina foi obtido em bons rendimentos e a síntese de chaiyaphumine A e derivado foi testada em fase sólida, em solução e empregando combinação dos dois métodos. O peptídeo desotamide B e ciclozantoxilano A foram sintetizados, mesmo que em baixo rendimentos, em fase sólida com ciclização solução. Ainda, a síntese de desotamide B também foi possível através da metodologia \"safety-catch\". Por fim, realizamos análise sistemática das propriedades físico-químicas e estruturais dos peptídeos no mercado e em fase clínica e comparamos os resultados obtidos com os alvos desse estudo / The use of peptides in therapy presents several limitations, from physicochemical characteristics to inadequate pharmacokinetic profile for oral absorption. However, new synthetic strategies for cost reduction and increase of the chemical and metabolic stability of peptides associated with alternative routes of administration were developed and allowed access to these molecules in the pharmaceutical market. Therefore, natural bioactive peptides, is an underexploited class from the medicinal chemist\'s point of view, are considered good prototypes for the development of similar series, generating information relevant to understanding the relationship between chemical structure and biological activity of these compounds. In the present study, cyclic peptides rufomycin B (antituberculosis activity), chaiyaphumine A (anti-malarial), cyclozanthoxylane A and desotamide were studied from the synthetic point of view, through different metodologies. In this sense, the amino acids Fmoc-N-Methyl-L-Leu and Fmoc-L-crotyl-Gly were synthetized in good yields for the total synthesis of rufomycin B. The amino acid Phenyl-acetyl-L-threonine was obtained in high yield and the synthetic studies on the chaiyaphumine A and analogue has been performed in solution and solid phase peptide synthesis and also through the combination of the 2 methods. The peptides desotamide B and cyclozanthoxylane A were synthetized, in low yields, in solid phase and in solution cyclization. Desotamide B could also be synthetized through safety-catch solid phase method. At end, we performed a systematic review of the physical chemical properties of all market and on clinical trial peptide drugs and we compared the results with the target molecules in this study.

Inhibiting therapeutically important protein-protein interactions has been a tremendous challenge for medicinal chemists. The folded 3D structures of peptides and proteins, mainly comprise secondary structural elements i.e α-helices and β-sheet have created an opportunity to design small molecules and peptidomimetic inhibitors of protein-protein interaction (PPI). Hence, information about the formation and stabilization of these secondary structures is vital for designing future drugs. In this dissertation, several cyclic beta-hairpin peptidomimetics that mimic the recognition surface have been designed and synthesized as inhibitors for different targets such as integrin mediated extracellular matrix -cell adhesion in multiple myeloma, p53-MDM2 PPI, amyloid beta fibrillogenesis inhibitor. Cyclization of linear peptides to restrict the number of conformations available to the linear peptide can increase its affinity for the target as well as increase its proteolytic resistance. In this study, different beta turn promoters that increase the propensity of cyclic peptides to adopt beta-sheet structures have been designed and synthesized. Chapter two discusses the design and synthesis of several cyclic III (Integrin Interaction Inhibitor) peptides that block adhesion of integrins to extracellular matrix components in Multiple Myeloma tumor cells. These cyclic peptides, as assayed by TOPRO 3 assay were more potent than the parent linear peptide with a bio-activity of 1.08 μM. We have also studied structure activity relationships (SAR) of these cyclic III peptide analogs to increase the potency and bioavailability of these peptides. Chapter three describes the application of cyclic beta-hairpin peptidomimetics to inhibit abeta fibrillogenesis that is responsible for Alzheimer’s disease. We have successfully designed and synthesized cyclic peptides that target the hydrophobic region (17-21) of abeta fibril which is believed to cause self aggregation and plaque formation. We have also successfully explored these cyclic beta-hairpin peptides to disrupt p53-MDM2 interactions. Chapter five discusses the design and synthesis of novel cysteine based Peptide Nucleic Acid (PNA) monomers that are aimed to increase cellular uptake by introducing positively charged species attached to the cysteine side chain. We have successfully synthesized CPNA monomers and made efforts to make PNA oligomers.

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Submitted by ANTONIO FERNANDEZ BOBEY null (antoniofernandezbobey86@yahoo.es) on 2016-04-12T19:44:51Z No. of bitstreams: 1 Dissertação_Versão Final_ Repositorio Unesp.pdf: 2495633 bytes, checksum: f7ff8d9ec49134a24d9a1082b09926dc (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-04-15T17:37:25Z (GMT) No. of bitstreams: 1 fernandezbobey_a_me_araiq_par.pdf: 909965 bytes, checksum: 12ae7f0b3b5f6a97678bcbd7f2a70506 (MD5) / Made available in DSpace on 2016-04-15T17:37:25Z (GMT). No. of bitstreams: 1 fernandezbobey_a_me_araiq_par.pdf: 909965 bytes, checksum: 12ae7f0b3b5f6a97678bcbd7f2a70506 (MD5) Previous issue date: 2016-02-24 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Os ciclotídeos são produtos naturais de estrutura polipeptídica, contendo de 28 a 37 resíduos de aminoácidos, sendo seis deles resíduos de cisteína, altamente conservados e formados por ligações dissulfeto as quais exibem ciclização tipo "cabeça-cauda". Esse arranjo estrutural característico confere aos ciclotídeos uma estabilidade excepcional e resistência à proteólise. Devido a estas peculiaridades moleculares os ciclotídeos são substâncias com importantes funções biológicas, entre elas, destacam-se as de defesa e adaptação dos organismos que as acumulam. São de grande interesse para agricultura, agindo como inseticidas e, no uso medicinal por apresentarem atividades anti-HIV, anti-helmíntica, antimicrobiana e efeitos uterotônicos. A presente dissertação trata do estudo de ciclotídeos isolados da planta Noisettia orchidiflora (Rudge) Gingins, pertencente à família Violaceae, um táxon de ocorrência frequente na Mata Atlântica. Já existem dados na literatura sobre o estudo de ciclotídeos das raízes e o presente estudo é importante na medida que registra a ocorrência desta classe de substâncias e a sua caracterização nas folhas e galhos desta espécie, levando a informações mais completas sobre a ocorrência de ciclotídeos em Violaceae. A extração de ciclotídeos do material vegetal (galhos e folhas secos e moídos) foi feita mediante maceração hidrometanólica até esgotamento do material vegetal, seguida de partição líquido-líquido com diclorometano. A fase polar foi concentrada e submetida à cromatografia em coluna, empregando octadecilsilano (C18) como fase estacionária, obtendo-se frações ricas em peptídeos. O processo de purificação foi realizado por HPLC preparativo e/ou analítico com eluição gradiente, empregando-se acetonitrila e água como fase móvel, o que permitiu a obtenção das substâncias. A sequência de aminoácidos (estrutura primária) dos ciclotídeos isolados foi estabelecida por Espectrometria de Massas MALDI-TOF/TOF com o auxílio das reações de redução, alquilação e digestão enzimática empregando as enzimas: endoproteinase de ácido glutâmico (endoGlu-C), tripsina e quimiotripsina. Também, foi realizada a análise de aminoácidos das substâncias, permitindo a quantificação de cada aminoácido presente. A presente pesquisa resultou no isolamento de seis compostos de galhos e três oriundos de folhas, totalizando sete diferentes possíveis ciclotídeos, visto que dois deles foram comuns para ambos os tecidos. Até o momento foi possível determinar a estrutura primária de quatro deles: Os ciclotídeos Nor B (substância F20-2), massa molecular 3180,416 Da, Nor C (substância F20-3), massa molecular 3282,472 Da, Nor D (substância F17-1), massa molecular 3249,474 Da e Nor E (substância F21-1), massa molecular 3170,472 Da. Todos eles reportados pela primeira vez no presente estudo. As demais substâncias isoladas se encontram em processo caracterização estrutural. / Cyclotides are polypeptide structures, comprise 28-37 amino acid residues, six of them, are cysteine residues, highly conserved and formed by disulfide bonds, which exhibit "head-tail" cyclization type. This structural feature gives to cyclotides remarkable stability and resistance to proteolysis. Due to these singularities, such compounds have disclosed important biological functions. Among them; the literature has highlighted important ecological properties as defense and adaptation of the organisms, which accumulate these natural products. Accordingly, they are of great interest to agriculture, acting as insecticide, and to medicine, since some compounds have displayed anti-HIV activity, anthelmintic, antimicrobial and uterotonic properties. This research deals with the study of cyclotides isolated Noisettia orchidiflora (Rudge) Gingins, belonging to the taxon Violaceae, which frequently occurs in the Atlantic Forest. There are several studies in the literature on the occurrence of this class of compounds and their characterization in the leaves and branches of Violaceae plant species, leading to more complete information on the occurrence of cyclotides, and their biological significance for these plants. The cyclotides extraction of plant material (dried and ground branches and leaves) was carried out by maceration with methanol/water, followed by a liquid-liquid partition with dichloromethane. The polar phase was concentrated and subjected to chromatographic column using octadecylsilane (C18) as stationary phase, achieving several fractions rich in peptides. The purification process was performed by analytical and/or preparative HPLC, in gradient of acetonitrile and water as mobile phase, which led to the isolation of the cyclotides. The amino acid sequence (primary structure) of the isolated compounds was established by MALDI-TOF/TOF by reduction and alkylation reactions as well as enzymatic digestion using the enzymes: endoproteinase glutamic acid (endoGlu-C), trypsin and chymotrypsin. Also, the quantification of each amino acid present in the cyclotide structures was performed, and this amino acid analysis was fundamental for the characterization of these substances. Therefore, this research resulted in the isolation of the six compounds accumulated in the branches, and 3 of them were also found in the leaves. A complete analysis of all peptides suggested that seven are cyclotides, while two of them were common for both twigs and leaves tissues. Until now it was possible to determine the primary structure of four cyclotides, which is being described in plants for the first time: The cyclotides Nor B (F20-2 substance), molecular weight 3180.416 Da, Nor C (F20-3 substance), molecular weight 3282.472 Da, Nor D (substance F17-1), molecular mass 3249.474 Da Nor E (F21-1 substance), molecular weight 3170.472 Da. All these cyclotides are being reported for the first time in this study, however, 3 of these are currently under further analytical studies aimed at the complete structural characterization. / CNPq: 133418/2014-6

<div>Cyclic peptides are important sources of medicines. </div><div>They are advantageous compared to linear peptides because they possess lower flexibility, which allows for high-affinity target binding and enhanced proteolytic stability. Unfortunately, achieving head-to-tail cyclization of peptides is quite challenging, as it is hard to control efficiency and regiospecificity of peptide macrocyclization. Many have attempted to improve peptide cyclization, including the use of different synthetic reagents as well as synthetic techniques to allow amide-bond formation and promote cyclization. While these strategies have offered great potential solutions, the aim of this study is to explore an alternative strategy that utilizes biocatalysis as a method of achieving successful peptide cyclization. Biocatalysis is the use of enzymes as natural process catalysts under artificial in vitro conditions. Biocatalysis is often more environmentally friendly and safer compared to traditional organic synthesis methods. Non-ribosomal peptide synthetases (NRPSs) are one of the major sources of cyclic peptides in nature. These are systems of large multifunctional proteins are organized into functional domains that act as an assembly line to generate peptide natural products. Normally, the thioesterase domain is responsible for hydrolysis and cyclization of the peptide. Recently, a novel cyclase (SurE) that is physically discrete from the NRPS was discovered. Based on this unique quality, we hypothesized that SurE would be easier to express compared to thioesterase domains and, for this reason, SurE could be a fantastic biocatalyst for the cyclization of peptides. To test this, we designed and generated an expression vector for SurE. We then expressed and purified the SurE protein. We also synthesized three linear peptides of varying lengths. To test for SurE activity, we attempted to add N-acetylcysteamine (SNAC) to mimic its native substrate. Unfortunately, we were unable to successfully attach the SNAC to our linear peptide. To combat this issue, a new synthesis strategy is currently being developed. This work is currently ongoing in the Parkinson lab, with the aim being to test the SurE protein, as well as other PBP-like cyclases, on other modified linear peptides and demonstrate whether the protein has the ability to cyclase a wide scope of peptides.</div><div><br></div>

miRNA sind kurze 21 – 23 nukleotidlange nicht kodierende RNAs endogenen Ursprungs und regulieren auf post-transkriptionaler Ebene die Genexpression. Da aberrante Expressionsmuster der miRNAs im Zusammenhang mit verschiedenen Krankheiten stehen, ist das Interesse groß, Kontrolle über die miRNA-vermittelte Genexpression zu erhalten. Bei Krankheitsbildern, die eine Überexpression der miRNA aufweisen, kann die Inhibition der miRNA Reifung als Therapieansatz dienen. Inhibition kann z. B. durch peptidische Strukturen und durch small molecules, wie Aminoglykoside erfolgen. Ziel dieser Arbeit war die nahezu vollständig festphasenbasierte Synthese von zyklischen Peptiden und Peptid-Aminoglykosid-Konjugaten als potentielle Inhibitoren der miRNA Reifung. Ferner sollte die Guanidinylierung an fester Phase mit verschiedenen Testsubstraten gezeigt werden. In der vorliegenden Arbeit wurden im ersten Teilprojekt zehn zyklische Peptide mit Hilfe eines bisfunktionalen Linkermoleküls in den Seitenketten zweier im Peptid enthaltener Cysteine synthetisiert und isoliert. Basierend darauf wurden neun weitere zyklische Peptide an fester Phase synthetisiert, mit ausgewählten Aminoglykosiden in einer CuAAC gebunden und erfolgreich isoliert. Im zweiten Teilprojekt dieser Arbeit wurde die Guanidinylierung an fester Phase mittels des Goodman’s Reagent gezeigt. In ersten Studien wurden vier Testpeptide an fester Phase guanidinyliert. Im Anschluss wurde die Limitierung dieser Methode geprüft. Dazu wurden Aminoglykoside mittels CuAAC an verschiedene Peptid- und Peptid PNA-Rückgrate geknüpft und guanidinyliert. Nicht für alle Substrate konnte die vollständige Guanidinylierung an fester Phase gezeigt werden. Ein weiteres Teilprojekt zeigte die Funktionalisierung von kommerziell erhältlichen Polymeren für die SPPS in Hinsicht auf fluorophorbasierte „Hochdurchsatz Screening-Methoden“. Dazu wurde ein peptidischer Spacer entworfen, der eine Knüpfungsstelle für Fluorophore mittels CuAAC enthielt. / miRNA are short long non-coding RNAs endogenous origin with a length of 21 – 23 nucleotides. MicroRNAs regulate the gene expression on post-transcriptionally level. Starting in the nucleus, primary transcripts are processed into precursor-miRNAs. Accordingly, the miRNA matures after export into cytosol. Since aberrant expression patterns are related to different diseases, it’s from interest to gain control about miRNA mediated gene expression. Some diseases are related to over expression of miRNA. For that reason, the inhibition of the miRNA maturing is object of research. The inhibition can be resulted from peptide structures or with small molecules like aminoglycosides. Aim of this work was the solid phase synthesis of cyclic peptides derivatives and peptide aminoglycoside conjugates as potential inhibitors of the miRNA maturing. In addition, the guanidinylation on solid phase should be evidenced with different substrates. In the first part of the project ten cyclic peptides were synthesized on solid phase. The cyclization was carried out with a bifunctional linking molecule in the side chains of two cysteines. Based on that nine cyclic peptides were synthesized and elected aminoglycosides were bound with help of CuAAC. The second part of this work showed the guanidinylation on solid phase by using Goodman’s reagent under mild conditions. Four peptides were used for initial studies. Due to the success of this method the limit was evaluated. Therefore, aminoglycosides were bound via CuAAC to different peptide and peptide-PNA backbones. By mischance, not all the chosen substrates were fully guanidinylated on solid phase. A further short project showed the functionalization of commercially available resins for solid phase peptide synthesis in relation to fluorophore based high throughput screening methods. For this purpose, a peptide spacer was devised with a binding site for fluorophores via CuAAC.

Diante da ausência de tratamentos eficazes para a esclerose múltipla (EM) e sabendo que compostos animais têm sido usados como protótipos para o desenvolvimento de novas drogas, avaliamos o efeito do Tnp, um peptídeo cíclico inédito e com potencial antiinflamatório derivado do veneno de Thalassophryne nattereri, na encefalomielite autoimune experimental (EAE), um modelo representativo da EM. Demonstramos que o Tnp em distintos esquemas de tratamento por mecanismos também dependentes de IL-10 consegue diminuir a intensidade dos sintomas clínicos e adiar o pico de aparecimento dos sintomas graves na EAE por suprimir DC convencionais e propiciar DC plasmocitóides; por bloquear a infiltração de leucócitos e a reativação de clones Th1, Th17, microglia e macrófagos no SNC; por favorecer o aumento de células reguladoras e ainda por ultrapassar a BHE e alcançar o órgão alvo. O Tnp atenua a neuroinflamação e previne a desmielinização, refletindo assim na melhoria dos sinais clínicos na EAE, tornando-se um importante candidato para o tratamento da EM. / Given the lack of effective treatments for multiple sclerosis (MS) and knowing that venomous have been used as prototype for the development of new drugs here we evaluated the effect of the Tnp, a described antiinflammatory cyclic peptide identified in the venom of Thalassophryne nattereri, on experimental autoimmune encephalomyelitis (EAE), a representative model of MS. We found that distinct treatments of Tnp by mechanisms also dependent on IL-10 significantly reduced the clinical severity of EAE. Tnp was related with: suppression of the activation state of conventional DC and the emergence of plasmacytoid DC; blocking the leukocyte infiltration and the reactivation of Th1, Th17, microglia cells and macrophages in the CNS; increasing of regulatory cells and also Tnp can overcome the BBB and reach the target organ. Tnp can reduce the severity of symptoms and delay the peak of onset of severe symptoms. These results shed light on the role of Tnp a small molecule in the regulation of inflammation and provides a new therapeutic opportunity for the treatment of MS.