Proteomics: Unraveling the Cross Talk Between Innate Immunity and Disease Pathophysiology, Diagnostics, and Treatment Options.

Inflammation is crucial in diseases, and proteins play a key role in the interplay between innate immunity and pathology. This review explores how proteomics helps understanding this relationship, focusing on diagnosis and treatment. We explore the dynamic innate response and the significance of proteomic techniques in deciphering the complex network of proteins involved in prevalent diseases, including infections, cancer, autoimmune and neurodegenerative disorders. Proteomics identifies key proteins in host-pathogen interactions, shedding light on infection mechanisms and inflammation. These discoveries hold promise for diagnostic tools, therapies, and vaccines. In cancer research, proteomics reveals innate signatures associated with tumor development, immune evasion, and therapeutic response. Additionally, proteomic analysis has unveiled autoantigens and dysregulation of the innate immune system in autoimmunity, offering opportunities for early diagnosis, disease monitoring, and new therapeutic targets. Moreover, proteomic analysis has identified altered protein expression patterns in neurodegenerative diseases like Alzheimer's and Parkinson's, providing insights into potential therapeutic strategies. Proteomics of the innate immune system provides a comprehensive understanding of disease mechanisms, identifies biomarkers, and enables effective interventions in various diseases. Despite still in its early stages, this approach holds great promise to revolutionize innate immunity research and significantly improve patient outcomes across a wide range of diseases.

Purification and Biological Properties of Raniseptins-3 and -6, Two Antimicrobial Peptides from Boana raniceps (Cope, 1862) Skin Secretion.

The number of multidrug-resistant pathogenic microorganisms has been growing in recent years, most of which is due to the inappropriate use of the commercial antibiotics that are currently available. The dissemination of antimicrobial resistance represents a serious global public health problem. Thus, it is necessary to search for and develop new drugs that can act as antimicrobial agents. Antimicrobial peptides are a promising alternative for the development of new therapeutic drugs. Anurans' skin glands are a rich source of broad-spectrum antimicrobial compounds and hylids, a large and diverse family of tree frogs, are known as an important source of antimicrobial peptides. In the present study, two novel antimicrobial peptides, named Raniseptins-3 and -6, were isolated from Boana raniceps skin secretion and their structural and biological properties were evaluated. Raniseptins-3 and -6 are cationic, rich in hydrophobic residues, and adopt an α-helix conformation in the presence of SDS (35 mM). Both peptides are active against Gram-negative bacteria and Gram-positive pathogens, with low hemolytic activity at therapeutic concentrations. No activity was observed for yeasts, but the peptides are highly cytotoxic against B16F10 murine melanoma cells and NIH3T3 mouse fibroblast cells. None of the tested compounds showed improvement trends in the MTT and LDH parameters of MHV-3 infected cells at the concentrations tested.

Mastoparans: A Group of Multifunctional α-Helical Peptides With Promising Therapeutic Properties.

Biologically active peptides have been attracting increasing attention, whether to improve the understanding of their mechanisms of action or in the search for new therapeutic drugs. Wasp venoms have been explored as a remarkable source for these molecules. In this review, the main findings on the group of wasp linear cationic α-helical peptides called mastoparans were discussed. These compounds have a wide variety of biological effects, including mast cell degranulation, activation of protein G, phospholipase A2, C, and D activation, serotonin and insulin release, and antimicrobial, hemolytic, and anticancer activities, which could lead to the development of new therapeutic agents.

Figainin 1, a Novel Amphibian Skin Peptide with Antimicrobial and Antiproliferative Properties.

Amphibian skin secretions are abundant in bioactive compounds, especially antimicrobial peptides. These molecules are generally cationic and rich in hydrophobic amino acids, have an amphipathic structure and adopt an α-helical conformation when in contact with microorganisms membranes. In this work, we purified and characterized Figainin 1, a novel antimicrobial and antiproliferative peptide from the cutaneous secretion of the frog Boana raniceps. Figainin 1 is a cationic peptide with eighteen amino acid residues-rich in leucine and isoleucine, with an amidated C-terminus-and adopts an α-helical conformation in the presence of trifluoroethanol (TFE). It displayed activity against Gram-negative and especially Gram-positive bacteria, with MIC values ranging from 2 to 16 µM, and showed an IC50 value of 15.9 µM against epimastigote forms of T. cruzi; however, Figanin 1 did not show activity against Candida species. This peptide also showed cytolytic effects against human erythrocytes with an HC50 of 10 µM, in addition to antiproliferative activity against cancer cells and murine fibroblasts, with IC50 values ranging from 10.5 to 13.7 µM. Despite its adverse effects on noncancerous cells, Figainin 1 exhibits interesting properties for the development of new anticancer agents and anti-infective drugs against pathogenic microorganisms.

Scorpion Toxins and Ion Channels: Potential Applications in Cancer Therapy.

Apoptosis, a genetically directed process of cell death, has been studied for many years, and the biochemical mechanisms that surround it are well known and described. There are at least three pathways by which apoptosis occurs, and each pathway depends on extra or intracellular processes for activation. Apoptosis is a vital process, but disturbances in proliferation and cell death rates can lead to the development of diseases like cancer. Several compounds, isolated from scorpion venoms, exhibit inhibitory effects on different cancer cells. Indeed, some of these compounds can differentiate between healthy and cancer cells within the same tissue. During the carcinogenic process, morphological, biochemical, and biological changes occur that enable these compounds to modulate cancer but not healthy cells. This review highlights cancer cell features that enable modulation by scorpion neurotoxins. The properties of the isolated scorpion neurotoxins in cancer cells and the potential uses of these compounds as alternative treatments for cancer are discussed.

Biological Properties of a Novel Multifunctional Host Defense Peptide from the Skin Secretion of the Chaco Tree Frog, Boana raniceps.

In recent years, the number of new antimicrobial drugs launched on the market has decreased considerably even though there has been an increase in the number of resistant microbial strains. Thus, antimicrobial resistance has become a serious public health problem. Amphibian skin secretions are a rich source of host defense peptides, which generally are cationic and hydrophobic molecules, with a broad-spectrum of activity. In this study, one novel multifunctional defense peptide was isolated from the skin secretion of the Chaco tree frog, Boana raniceps. Figainin 2 (1FLGAILKIGHALAKTVLPMVTNAFKPKQ28) is cationic and hydrophobic, adopts an α-helical structure in 50% (v/v) trifluoroethanol (TFE), and is thermally stable. This peptide exhibited activity against Gram-negative and Gram-positive pathogenic bacteria arboviruses, T. cruzi epimastigotes; however, it did not show activity against yeasts. Figainin 2 also showed antiproliferative activity on cancer cells, is moderately active on human erythrocytes, and activates the oxidative burst in human neutrophils.

The vertical radiation dose profile and decision-making in a simulated urban event.

A radiological dispersal device (RDD) is built using an explosive device laced with radioactive materials. The RDD appears as a speculative radiological weapon with the aim of spreading radioactive material across an inhabited area. This study seeks to evaluate how the official decision-making process is influenced by the radiation vertical profile dose, using the hypothetical scenario of a simulated RDD detonation in a densely populated urban area. A simulated plume of strong radiation was generated from the explosion site, contaminating the surrounding area. Several atmospheric conditions impact on the contamination. However, this study focusses on the following main variables considered by HotSpot for a conservative simulation: (a) the atmospheric stability conditions (Pasquill-Gifford - PG classes); (b) the explosive power, and (c) the source-term. Gaussian modeling was used for its speed, and for its capacity to estimate the time-integrated atmospheric concentration of an aerosol at any point in 3D space. The simulation provided information about four main outcomes: (a) contamination plume area; (b) radiological risk dependency on PG classes; (c) total effective dose equivalent (TEDE) with a possible dependence on receptor height; and (d) potentially affected population's size. The findings suggest that a protocolled response from authorities should be implemented in order to effectively follow possible changes in the PG class. Which, in turn, may negatively impact the decision-making process.

Analysis of the Effect of Intestinal Ischemia and Reperfusion on the Rat Neutrophils Proteome.

Intestinal ischemia and reperfusion injury is a model system of possible consequences of severe trauma and surgery, which might result into tissue dysfunction and organ failure. Neutrophils contribute to the injuries preceded by ischemia and reperfusion. However, the mechanisms by which intestinal ischemia and reperfusion stimulate and activate circulating neutrophils is still not clear. In this work, we used proteomics approach to explore the underlying regulated mechanisms in Wistar rat neutrophils after ischemia and reperfusion. We isolated neutrophils from three different biological groups; control, sham laparotomy, and intestinal ischemia/reperfusion. In the workflow, we included iTRAQ-labeling quantification and peptide fractionation using HILIC prior to LC-MS/MS analysis. From proteomic analysis, we identified 2,045 proteins in total that were grouped into five different clusters based on their regulation trend between the experimental groups. A total of 417 proteins were found as significantly regulated in at least one of the analyzed conditions. Interestingly, the enzyme prediction analysis revealed that ischemia/reperfusion significantly reduced the relative abundance of most of the antioxidant and pro-survival molecules to cause more tissue damage and ROS production whereas some of the significantly up regulated enzymes were involved in cytoskeletal rearrangement, adhesion and migration. Clusters based KEGG pathways analysis revealed high motility, phagocytosis, directional migration, and activation of the cytoskeletal machinery in neutrophils after ischemia and reperfusion. Increased ROS production and decreased phagocytosis were experimentally validated by microscopy assays. Taken together, our findings provide a characterization of the rat neutrophil response to intestinal ischemia and reperfusion and the possible mechanisms involved in the tissue injury by neutrophils after intestinal ischemia and reperfusion.

Hikikomori: revisão sobre um grave fenômeno de isolamento social / Hikikomori: review on a severe phenomenon of social withdrawal

RESUMO Objetivos Expandir os conhecimentos sobre o fenômeno de isolamento social prolongado, voluntário e grave denominado hikikomori e facilitar a identificação e o acompanhamento terapêutico desses indivíduos. Métodos Foi realizada uma revisão da literatura de 2000 a 2017, sendo utilizadas várias bases de dados como instrumentos de busca usando as palavras-chave: "hikikomori", "youth social withdrawal" e "isolamento social prolongado". Resultados O hikikomori foi descrito inicialmente no Japão, sendo considerado uma síndrome ligada à cultura nipônica. Porém, nos últimos anos foi descrito em diversos países, inclusive no ocidente. Afeta principalmente adolescentes e adultos jovens do sexo masculino, os quais vivem espontaneamente reclusos em seus quartos por pelo menos seis meses. São pessoas solitárias, tímidas, com um suporte social deficiente e que, frequentemente, tiveram alguma experiência traumática na infância. A maioria dos indivíduos apresenta algum transtorno psiquiátrico associado. O fenômeno acarreta terríveis prejuízos para o indivíduo, familiares e para a sociedade como um todo. Conclusão O hikikomori é subdiagnosticado e subtratado fora do Japão, pelo desconhecimento dos profissionais da saúde e pela recusa dos portadores em buscar ajuda. O fenômeno ainda não foi incluído numa categoria de diagnóstico psiquiátrico, o que dificulta a padronização e a realização de pesquisas ao redor do mundo.

ABSTRACT Objectives To expand the current knowledge on the phenomenon of severe, voluntary and prolonged social withdrawal called hikikomori, and to facilitate the identification and treatment of these individuals. Methods A comprehensive review of the literature from 2000 to 2017 has been conducted, using several data bases as search instruments using the keywords "hikikomori", "youth social withdrawal" and "prolonged social isolation". Results Hikikomori was firstly described in Japan and was considered a culture-bound syndrome. However, in the last years, it has been described in several other countries, including western countries. It affects mainly male adolescents and young adults, who spontaneously live recluse in their rooms, for at least six months. They are lonely and shy people, with insufficient social support, who frequently had some traumatic experience in childhood. Most of them present some associated psychiatric disorder. The phenomenon leads to terrible losses to the individuals, their families and to society. Conclusion Hikikomori is an underdiagnosed and undertreated condition outside Japan, due to the lack of knowledge of health professionals, and for the sufferers' refusal to seek help. The phenomenon was not yet included as a psychiatric disorder in the classifications, what difficults the standardization and conduction of research around the world.

A Timely Shift from Shotgun to Targeted Proteomics and How It Can Be Groundbreaking for Cancer Research.

The fact that cancer is a leading cause of death all around the world has naturally sparked major efforts in the pursuit of novel and more efficient biomarkers that could better serve as diagnostic tools, prognostic predictors, or therapeutical targets in the battle against this type of disease. Mass spectrometry-based proteomics has proven itself as a robust and logical alternative to the immuno-based methods that once dominated the field. Nevertheless, intrinsic limitations of classic proteomic approaches such as the natural gap between shotgun discovery-based methods and clinically applicable results have called for the implementation of more direct, hypothesis-based studies such as those made available through targeted approaches, that might be able to streamline biomarker discovery and validation as a means to increase survivability of affected patients. In fact, the paradigm shifting potential of modern targeted proteomics applied to cancer research can be demonstrated by the large number of advancements and increasing examples of new and more useful biomarkers found during the course of this review in different aspects of cancer research. Out of the many studies dedicated to cancer biomarker discovery, we were able to devise some clear trends, such as the fact that breast cancer is the most common type of tumor studied and that most of the research for any given type of cancer is focused on the discovery diagnostic biomarkers, with the exception of those that rely on samples other than plasma and serum, which are generally aimed toward prognostic markers. Interestingly, the most common type of targeted approach is based on stable isotope dilution-selected reaction monitoring protocols for quantification of the target molecules. Overall, this reinforces that notion that targeted proteomics has already started to fulfill its role as a groundbreaking strategy that may enable researchers to catapult the number of viable, effective, and validated biomarkers in cancer clinical practice.

High performance mass spectrometry based proteomics reveals enzyme and signaling pathway regulation in neutrophils during the early stage of surgical trauma.

PURPOSE: In clinical conditions trauma is associated with high mortality and morbidity. Neutrophils play a key role in the development of multiple organ failure after trauma EXPERIMENTAL DESIGN: To have a detailed understanding of the neutrophil activation at primary stages after trauma, neutrophils are isolated from control and surgical trauma rats in this study. Extracted proteins are analyzed using nano liquid chromatography coupled with tandem mass spectrometry. RESULTS: A total of 2924 rat neutrophil proteins are identified in our analysis, of which 393 are found differentially regulated between control and trauma groups. By using functional pathways analysis of the 190 proteins up-regulated in surgical trauma, we found proteins related to transcription initiation and protein biosynthesis. On the other hand, among the 203 proteins down-regulated in surgical trauma we found enrichment for proteins of the immune response, proteasome degradation and actin cytoskeleton. Overall, enzyme prediction analysis revealed that regulated enzymes are directly involved in neutrophil apoptosis, directional migration and chemotaxis. Our observations are then confirmed by in silico protein-protein interaction analysis. CONCLUSIONS AND CLINICAL RELEVANCE: Collectively, our results reveal that neutrophils drastically regulate their biochemical pathways after the early stages of surgical trauma, showing lower activity. This implies higher susceptibility of the trauma patients to infection and bystander tissues damage.

Marine Depsipeptides as Promising Pharmacotherapeutic Agents.

Depsipeptides are a group of biologically active peptides that have at least one of the amide bonds replaced by an ester bond. These peptides sometimes present additional chemical modifications, including unusual amino acid residues in their structures. Depsipeptides are known to exhibit a large array of bioactivities, such as anticancer, antiproliferative, antimicrobial, antiviral and antiplasmodial properties. They are commonly found in marine organisms: bacteria, tunicates, mollusks, sponges, and others. Herein, we summarize the latest insights about marine depsipeptides, their mechanisms of action and potential as therapeutic agents.

The Amazing World of Peptide Engineering: the Example of Antimicrobial Peptides from Frogs and Their Analogues.

This review discusses the importance and properties of antimicrobial peptides from frogs and their synthetic analogues as potential therapeutic alternatives in fighting not only bacterial infections, but also protozoans involved with the major neglected diseases, which afflict human populations (e.g., Chagas disease, African sleeping sickness, Leishmaniasis and malaria). Here, we emphasize their multifunctional properties such as promising broad-spectrum drugs that target protozoan parasites too.

Cytotoxic Activity and Antiproliferative Effects of Crude Skin Secretion from Physalaemus nattereri (Anura: Leptodactylidae) on in vitro Melanoma Cells.

Anuran secretions are rich sources of bioactive molecules, including antimicrobial and antitumoral compounds. The aims of this study were to investigate the therapeutic potential of Physalaemus nattereri skin secretion against skin cancer cells, and to assess its cytotoxic action mechanisms on the murine melanoma cell line B16F10. Our results demonstrated that the crude secretion reduced the viability of B16F10 cells, causing changes in cell morphology (e.g., round shape and structure shrinkage), reduction in mitochondrial membrane potential, increase in phosphatidylserine exposure, and cell cycle arrest in S-phase. Together, these changes suggest that tumor cells die by apoptosis. This skin secretion was also subjected to chromatographic fractioning using RP-HPLC, and eluted fractions were assayed for antiproliferative and antibacterial activities. Three active fractions showed molecular mass components in a range compatible with peptides. Although the specific mechanisms causing the reduced cell viability and cytotoxicity after the treatment with crude secretion are still unknown, it may be considered that molecules, such as the peptides found in the secretion, are effective against B16F10 tumor cells. Considering the growing need for new anticancer drugs, data presented in this study strongly reinforce the validity of P. nattereri crude secretion as a rich source of new anticancer molecules.

Evaluation of the effects of ischemic preconditioning on the hematological parameters of rats subjected to intestinal ischemia and reperfusion

OBJECTIVES: Intestinal ischemia/reperfusion often leads to acute lung injury and multiple organ failure. Ischemic preconditioning is protective in nature and reduces tissue injuries in animal and human models. Although hematimetric parameters are widely used as diagnostic tools, there is no report of the influence of intestinal ischemia/reperfusion and ischemic preconditioning on such parameters. We evaluated the hematological changes during ischemia/reperfusion and preconditioning in rats. METHODS: Forty healthy rats were divided into four groups: control, laparotomy, intestinal ischemia/reperfusion and ischemic preconditioning. The intestinal ischemia/reperfusion group received 45 min of superior mesenteric artery occlusion, while the ischemic preconditioning group received 10 min of short ischemia and reperfusion before 45 min of prolonged occlusion. A cell counter was used to analyze blood obtained from rats before and after the surgical procedures and the hematological results were compared among the groups. RESULTS: The results showed significant differences in hematimetric parameters among the groups. The parameters that showed significant differences included lymphocyte, white blood cells and granulocyte counts; hematocrit; mean corpuscular hemoglobin concentration; red cell deviation width; platelet count; mean platelet volume; plateletcrit and platelet distribution width. CONCLUSION: The most remarkable parameters were those related to leukocytes and platelets. Some of the data, including the lymphocyte and granulocytes counts, suggest that ischemic preconditioning attenuates the effect of intestinal ischemia/reperfusion on circulating blood cells. Our work contributes to a better understanding of the hematological responses after intestinal ischemia/reperfusion and IPC, and the present findings may also be used as predictive values. .

Propostas de intervenção fonoaudiológica no autismo infantil: revisão sistemática da literatura / Proposals for speech therapy for autist children: a systematic review of literature / Propuestas de acción fonoaudiológica para el autismo infantil: una revisión sistemática de la literatura

Introdução: As alterações de linguagem no transtorno autístico geralmente são caracterizadas por atrasos significativos ou ausência total de desenvolvimento desta habilidade. Tais alterações lingüísticas confirmam a importância da atuação fonoaudiológica no trato dos pacientes com esse diagnóstico. A partir disso, é nítida a importância de conhecer as propostas de intervenções terapêuticas a serem utilizados. Objetivo geral: Revisar artigos atuais sobre propostas de intervenção fonoaudiológica no autismo infantil, por meio de literatura especializada. Método: Foi realizada pesquisa bibliográfica utilizando os bancos de dados eletrônicos Medline, Lilacs e SciELO (2006?2010). As palavras-chaves utilizadas em inglês foram: ?autistic disorder? e ?speech therapy? nas bases de dados Medline e Lilacs e em português:?autismo? e ?fonoaudiologia? na base de dados SciELO. Resultados: O total de artigos encontrados utilizando as palavras-chaves propostas foi de 117 e ao selecionarmos os artigos referentes aos anos entre 2006 e 2010, obtivemos 48 artigos. Conclusão: Foram encontradas 25 propostas de intervenção. Dessas, seis mostraram etapas progressivas de aplicação/desenvolvimento do método; sete são compostas por uma única etapa; nove são estratégias relacionadas a participantes, materiais e locais e três não foram detalhados em seus respectivos artigos...

The changes in language in autistic disorder are usually characterized by significant delays or total absence of development of this skill. These reports show the major changes in language in autism and thus confirm the importance of speech therapy in the treatment of patients with this diagnoses. It is clear the importance to meet the proposals of therapeutic interventions to be used. Objective: To review current articles on proposals of speech therapy for autistic children through literature. Method: Bibliographic search was performed using electronic data banks Medline, Lilacs and SciELO (2006 - 2010). The key words used in English were: ?Autistic disorder? and ?speech therapy? in the databases Medline and Lilacs and in Portuguese: ?Autism? and ?Speech? in the SciELO database. Results: There were 117 articles found with the key words, and selecting items for the years 2006 to 2010, we obtained 48 articles. Conclusion: There were 25 proposals of intervention, of these, six showed progressive steps of application / method development, seven were composed of a single step, nine are strategies related to the participants, materials and places and three were not detailed in their articles...

Introducción: Los cambios del lenguaje en el trastorno autístico por lo general son caracterizados por retrasos significativos o ausencia total en el desarrollo de esta habilidad. Tales cambios confirman la importancia de la actuación fonoaudiológica en el tratamiento de pacientes con este diagnóstico. De esto se desprende la importancia de conocer las propuestas de intervención terapéuticas a utilizar. Objetivo general: Revisar artículos actuales sobre propuestas de acción fonoaudiológica para el autismo infantil. Método: Se realizó búsqueda bibliográfica utilizando los bancos de datos electrónicos Medline, Lilacs y SciELO (2006 - 2010). Las palabras clave utilizadas en Inglés fueron: ?autistic disorder? y ?speech therapy? en las bases de datos Medline y Lilacs, y en portugués: ?autismo? y ?fonoaudiologia? en la base de datos SciELO. Resultados: El total de artículos encontrados con las palabra clave propuestas fue de 117 y en la selección de artículos para los años entre 2006 y 2010, se obtuvieron 48 artículos. Conclusión: Fueron encontradas 25 propuestas de intervención. De estas, seis mostraron pasos progresivos de aplicación / desarrollo del método; siete están compuestas de un solo paso; nueve son estrategias relacionadas a los participantes, los materiales y locales; y tres no están detalladas en sus respectivos artículos...

Anti-proliferative and cytotoxic activity of pentadactylin isolated from Leptodactylus labyrinthicus on melanoma cells.

Nowadays, the emergence of resistance to the current available chemotherapeutic drugs by cancer cells makes the development of new agents imperative. The skin secretion of amphibians is a natural rich source of antimicrobial peptides (AMP), and researchers have shown that some of these wide spectrum molecules are also toxic to cancer cells. The aim of this study was to verify a putative anticancer activity of the AMP pentadactylin isolated for the first time from the skin secretion of the frog Leptodactylus labyrinthicus and also to study its cytotoxic mechanism to the murine melanoma cell line B16F10. The results have shown that pentadactylin reduces the cell viability of B16F10 cells in a dose-dependent manner. It was also cytotoxic to normal human fibroblast cells; nevertheless, pentadactylin was more potent in the first case. The studies of action mechanism revealed that pentadactylin causes cell morphology alterations (e.g., round shape and shrinkage morphology), membrane disruption, DNA fragmentation, cell cycle arrest at the S phase, and alteration of mitochondrial membrane potential, suggesting that B16F10 cells die by apoptosis. The exact mechanism that causes reduction of cell viability and cytotoxicity after treatment with pentadactylin is still unknown. In conclusion, as cancer cells become resilient to death, it is worthwhile the discovery of new drugs such as pentadactylin that induces apoptosis.

Influence of N-terminus modifications on the biological activity, membrane interaction, and secondary structure of the antimicrobial peptide hylin-a1.

Recently the peptide Hy-a1 (IFGAILPLALGALKNLIK), with antimicrobial activity, was isolated from the skin secretion of the frog Hypsiboas albopunctatus. The aim of the present work was to evaluate four analogues with introduction of acetyl group, Asp or Lys at the N-terminus of antimicrobial peptide Hy-al to supply information about the relationship of structure-biological activity. The antimicrobial activities were assayed by measuring growth inhibition of four species of bacteria and four species of fungus. The hemolytic activity was also tested. The peptide containing Trp instead of Leu in position 6 (for fluorescence studies) presented MIC values comparable to wild type sequence: 32 µmol L(-1) , 32 µmol L(-1) , 8 µmol L(-1) , and 2 µmol L(-1) for E. coli, P. aeruginosa, S. aureus, and B. subtilis, respectively. Two peptides with this modification and containing one acetyl group or Asp residue at the N-terminal region showed activities only against Gram-positive bacteria. Different results were observed when the residue added was Lys. In this case, the activity against the microorganisms was sustained or increased. Conformational properties were investigated by CD techniques in water, TFE, and in zwitterionic micelles (LPC). The CD experiments demonstrated that, in water, the peptides had a random structure, but in TFE and LPC solutions they acquired an ordered structure, composed mainly by α-helix. However, these data have no relationship with activity against Gram-positive bacteria. These results showed that the N-terminal region of the peptide Hy-a1 has key roles in its antibacterial action toward different types of bacteria.

Hylin a1, the first cytolytic peptide isolated from the arboreal South American frog Hypsiboas albopunctatus ("spotted treefrog").

RP-HPLC fractionation of the electrically stimulated skin secretion of the arboreal South American frog Hypsiboas albopunctatus ("spotted treefrog") led to the isolation of a cytolytic C-terminally amidated peptide. This novel peptide, named hylin a1 (Hy-a1), consists of 18 amino acid residues (IFGAILPLALGALKNLIK-NH(2)). The alpha-helical structure of the synthetic hylin a1 peptide was confirmed by CD spectroscopy in the presence of 60% (v/v) TFE. The synthetic peptide displayed broad-spectrum antimicrobial activity against Gram-negative and Gram-positive bacteria including Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis and Pseudomonas aeruginosa and also against fungi (Candida albicans, C. krusei, C. parapsilosis and Cryptococcus neoformans). Hylin a1 was also able to disrupt human erytrocytes (HC(50)=18 microM). Similarity analysis using PSI-BLAST revealed 50-44% of identity to maximins Hv, H16, H15 and H10 from Bombina maxima and also to hylins b1 and b2 (Hy-b1 and Hy-b2) from Hypsiboas lundii (synonym: Hyla biobeba).