Esta tese foi realizada objetivando comparar 4 programas alimentares, em dietas à base de milho e farelo de soja, formuladas com ou sem restrição de proteína bruta (PB), suplementadas ou não com L-Val e L-Ile, e usando diferentes níveis de lisina digestível (dig.). Os programas alimentares (PRG) foram: PRG 1, PB limitada a um mínimo (22,4, 21,1, 19,8, 18,4% para as fases pré-inicial, inicial, crescimento e final, respectivamente, com relações de AA:Lis definidos apenas para Met+Cis (0,72) e Tre (0,65); PRG 2, a PB não foi restrita e as relações estendidas para Val (0,77) e Ile (0,67); PRG 3, mesmas restrições do PRG 2 e suplementadas com L-Val; PRG 4, mesmas restrições do PRG 3, e suplementadas com L-Ile. Dois experimentos foram realizados, um com 1.800 e outro com 4.800 pintos machos Cobb x Cobb 500 de 1 dia de idade. No primeiro experimento, as rações foram formuladas usando os 4 PRG e níveis de Lis dig. de 1,324%, 1,217%, 1,095% e 1,006% ou 5% maiores, para cada fase, totalizando 8 tratamentos e 9 repetições cada. Para o segundo experimento, os 4 PRG foram utilizados até 1-21 d, totalizando 4 tratamentos com 48 repetições. E de 22 a 42 dias, cada PRG foi subdividido nos 4 PRG, passando cada PRG da fase anterior a receber todos os 4 PRG para as fases de crescimento e final, totalizando 16 tratamentos com 12 repetições cada. Não houve interação entre os tratamentos em ambos os experimentos, com exceção para o ganho de peso (GP) e conversão alimentar (CA) de 36 a 43d, no primeiro experimento, onde aves alimentadas com PRG 2 demonstraram melhorias no GP e CA quando alimentadas com um aumento de 5% no nível de Lis. Também, o GP e a CA acumulados aos 35 e 43d foram melhores quando as aves foram alimentadas com o PRG 2, sem diferença estatística para o PRG 3 e 4. Um aumento em 5% no nível de Lis dig. resultou na melhoria da CA acumulativa aos 43d. A gordura abdominal, como porcentagem da carcaça eviscerada aos 43d, foi maior para as aves alimentadas com a PRG 1. No segundo experimento, as aves alimentadas com PRG 2 tiveram melhor CA de 22 a 42d e de 1 a 42d, mas sem diferença estatística para os PRG 3 e 4. As aves alimentadas com PGR 1 de 1 a 42d apresentou o menor GP e o pior CA sem diferenças entre os PGR 2 e 3, e os PGR 3 e 4, respectivamente. Os dados do presente estudo demonstram que a suplementação de dietas para frangos de corte com fontes sintéticas dos cinco primeiros AA limitantes permitiram resultados de desempenho semelhantes a uma dieta com PB restrita a um valor mínimo. / This thesis was carried out to compare four corn-soy feeding programs formulated with or without crude protein (CP) restrictions supplemented with or without L-Val and L-Ile, and using different digestible (dig.) Lys levels. Feeding programs (PRG) were: PRG 1, CP was restricted to a minimum (22.4, 21.1, 19.8, 18.4% for pre starter, starter, grower and finisher phases, respectively) with AA to Lys ratios set only for TSAA (0.72) and Thr (0.65); PRG 2, CP was not restricted while minimum ratios were also extended to Val (0.77) and Ile (0.67); PRG 3, restrictions were as in PRG 2 but with L-Val added; PRG 4, restrictions were as in PRG 3, but with L-Ile added. For this two experiments were conducted, one using 1,800 and the other using 4,800 oneday- old Cobb 500 male broiler chicks. For the first experiment, feeds had formulated using the 4 PRG and dig. Lys as 1.324%, 1.217%, 1.095% and 1.006% or 5% higher, for each phase, totaling 8 treatments with 9 replicates each. For the second experiment, the 4 PRG were used from 1 to 21 d, totaling 4 treatments with 48 replicates. From 22 to 42d, each PRG was subdivided in 4 PRG having the same rational as it was done to 21d, where each of the 4 PRG began receiving all 4 PRG for grower and finisher phases, totaling 16 treatments with 12 replicates each. No interaction was found between treatments in both experiments, with one exception for body weight gain (BWG) and feed conversion ratio (FCR) from 36 to 43d, in the first experiment, with birds fed PRG 2 demonstrating improvements in BWG and FCR when fed the 5% increasing in dig. Lys. And also, cumulative BWG and FCR at 35 and 43d and in each individual feeding phases showed broilers from PRG 2 having the best BWG and FCR; however, mean separations using Tukey showed no difference from birds fed PRG 3 and 4. Feeding a dietary program with 5% increase in dig. Lys resulted in improvement in cumulative FCR at 43d. Abdominal fat, as a percentage of the eviscerated carcass at 43d, was highest for birds fed the PRG 1. For the second experiment, birds fed with PRG 2 led to the best FCR from 22 to 42d and from 1 to 42d, but without statistical difference from PRG 3 and 4. Birds fed PGR 1 from 1 to 42d showed the lowest BWG and the highest FCR without statistical differences from PGR 2 and 3 and PGR 3 and 4, respectively. Data from the current study demonstrate that the supplementation of broiler diets with crystalline sources of the first five limiting AA allowed performance results similar to those produced when CP is restricted to a minimum.

Esta tese foi realizada objetivando comparar 4 programas alimentares, em dietas à base de milho e farelo de soja, formuladas com ou sem restrição de proteína bruta (PB), suplementadas ou não com L-Val e L-Ile, e usando diferentes níveis de lisina digestível (dig.). Os programas alimentares (PRG) foram: PRG 1, PB limitada a um mínimo (22,4, 21,1, 19,8, 18,4% para as fases pré-inicial, inicial, crescimento e final, respectivamente, com relações de AA:Lis definidos apenas para Met+Cis (0,72) e Tre (0,65); PRG 2, a PB não foi restrita e as relações estendidas para Val (0,77) e Ile (0,67); PRG 3, mesmas restrições do PRG 2 e suplementadas com L-Val; PRG 4, mesmas restrições do PRG 3, e suplementadas com L-Ile. Dois experimentos foram realizados, um com 1.800 e outro com 4.800 pintos machos Cobb x Cobb 500 de 1 dia de idade. No primeiro experimento, as rações foram formuladas usando os 4 PRG e níveis de Lis dig. de 1,324%, 1,217%, 1,095% e 1,006% ou 5% maiores, para cada fase, totalizando 8 tratamentos e 9 repetições cada. Para o segundo experimento, os 4 PRG foram utilizados até 1-21 d, totalizando 4 tratamentos com 48 repetições. E de 22 a 42 dias, cada PRG foi subdividido nos 4 PRG, passando cada PRG da fase anterior a receber todos os 4 PRG para as fases de crescimento e final, totalizando 16 tratamentos com 12 repetições cada. Não houve interação entre os tratamentos em ambos os experimentos, com exceção para o ganho de peso (GP) e conversão alimentar (CA) de 36 a 43d, no primeiro experimento, onde aves alimentadas com PRG 2 demonstraram melhorias no GP e CA quando alimentadas com um aumento de 5% no nível de Lis. Também, o GP e a CA acumulados aos 35 e 43d foram melhores quando as aves foram alimentadas com o PRG 2, sem diferença estatística para o PRG 3 e 4. Um aumento em 5% no nível de Lis dig. resultou na melhoria da CA acumulativa aos 43d. A gordura abdominal, como porcentagem da carcaça eviscerada aos 43d, foi maior para as aves alimentadas com a PRG 1. No segundo experimento, as aves alimentadas com PRG 2 tiveram melhor CA de 22 a 42d e de 1 a 42d, mas sem diferença estatística para os PRG 3 e 4. As aves alimentadas com PGR 1 de 1 a 42d apresentou o menor GP e o pior CA sem diferenças entre os PGR 2 e 3, e os PGR 3 e 4, respectivamente. Os dados do presente estudo demonstram que a suplementação de dietas para frangos de corte com fontes sintéticas dos cinco primeiros AA limitantes permitiram resultados de desempenho semelhantes a uma dieta com PB restrita a um valor mínimo. / This thesis was carried out to compare four corn-soy feeding programs formulated with or without crude protein (CP) restrictions supplemented with or without L-Val and L-Ile, and using different digestible (dig.) Lys levels. Feeding programs (PRG) were: PRG 1, CP was restricted to a minimum (22.4, 21.1, 19.8, 18.4% for pre starter, starter, grower and finisher phases, respectively) with AA to Lys ratios set only for TSAA (0.72) and Thr (0.65); PRG 2, CP was not restricted while minimum ratios were also extended to Val (0.77) and Ile (0.67); PRG 3, restrictions were as in PRG 2 but with L-Val added; PRG 4, restrictions were as in PRG 3, but with L-Ile added. For this two experiments were conducted, one using 1,800 and the other using 4,800 oneday- old Cobb 500 male broiler chicks. For the first experiment, feeds had formulated using the 4 PRG and dig. Lys as 1.324%, 1.217%, 1.095% and 1.006% or 5% higher, for each phase, totaling 8 treatments with 9 replicates each. For the second experiment, the 4 PRG were used from 1 to 21 d, totaling 4 treatments with 48 replicates. From 22 to 42d, each PRG was subdivided in 4 PRG having the same rational as it was done to 21d, where each of the 4 PRG began receiving all 4 PRG for grower and finisher phases, totaling 16 treatments with 12 replicates each. No interaction was found between treatments in both experiments, with one exception for body weight gain (BWG) and feed conversion ratio (FCR) from 36 to 43d, in the first experiment, with birds fed PRG 2 demonstrating improvements in BWG and FCR when fed the 5% increasing in dig. Lys. And also, cumulative BWG and FCR at 35 and 43d and in each individual feeding phases showed broilers from PRG 2 having the best BWG and FCR; however, mean separations using Tukey showed no difference from birds fed PRG 3 and 4. Feeding a dietary program with 5% increase in dig. Lys resulted in improvement in cumulative FCR at 43d. Abdominal fat, as a percentage of the eviscerated carcass at 43d, was highest for birds fed the PRG 1. For the second experiment, birds fed with PRG 2 led to the best FCR from 22 to 42d and from 1 to 42d, but without statistical difference from PRG 3 and 4. Birds fed PGR 1 from 1 to 42d showed the lowest BWG and the highest FCR without statistical differences from PGR 2 and 3 and PGR 3 and 4, respectively. Data from the current study demonstrate that the supplementation of broiler diets with crystalline sources of the first five limiting AA allowed performance results similar to those produced when CP is restricted to a minimum.

Angiotensin II (AII) immunoreactivity in the mesopontine area of the rat brain is distributed through several areas where co-localization of AII receptors has not been established. The current in vitro receptor autoradiography study re-examined the distribution of AII binding using 125I-Sar1, Ile8-AII ([125I]SIAII). When incubations were conducted without sulfhydryl reducing agents, [125I]SIAII binding was observed in the locus coeruleus, inferior colliculus, superior colliculus and the central gray in agreement with previous reports. Novel [125I]SIAII binding sites were detected in the parabrachial nucleus, pedunculopontine tegmental nucleus and the caudal linear raphe nucleus, corresponding with previously reported localization of AII immunoreactivity in these nuclei. [125I]SIAII binding was also found in the paragenual nucleus where the peptide has not been detected. Thus, the observation of novel AII receptors which are sensitive to sulfhydryl reducing agents, resolves several AII-AII receptor mismatches.

Doctor of Philosophy / Department of Human Nutrition / Tonatiuh Melgarejo / Background and Objective: Crohn’s disease (CD) patients express low levels of host defense peptides (HDPs) especially β-defensins, which may compromise intestinal barrier function. Antibiotic treatment for bacterial infections in CD is limited and rarely curative, making it necessary to find alternative therapeutic approaches. We therefore investigated to what extent an essential amino acid; L-isoleucine (L-ILE) might induce the expression of human β-defensins (HBDs) in colonic epithelial cells as an alternative approach to help patients with CD. Antimicrobial activity of HBD2 was also assessed against four bacterial isolates which can cause secondary infections in CD. Methods: HTB-37 Caco-2 cells were stimulated with L-ILE at a concentration of 0 - 500µg/ml for 6 hours. Total RNA was extracted using RNeasy Micro Kit (QIAGEN). Reverse transcription was carried out with Superscript ®III First-Strand Synthesis System. The cDNA was amplified using specific primers for HBD1-3. Antimicrobial activity of HBD2 was determined using the broth dilution assay. Results: HBD1 was constitutively expressed under all conditions. HBD2 was expressed in HTB-37 cells after stimulation with L-ILE. Below 25µg/ml L- ILE stimulation, no expression of HBD2 was observed. HBD2 exhibited antimicrobial activity against bacterial isolates tested, with a MIC of 32, 64 and 128 µg/ml for both strains of E. coli, S. aureus and P. aeruginosa respectively. Conclusions: Our results indicate that L-ILE stimulation of HTB-37 Caco-2 cells can induce HBD2 expression. Data collected from our in vitro studies might have major implications for modifying the intestinal microbiota towards a healthier state in CD patients. Promoting the expression of HBD2 by colonic cells may lead to a lower rate of infection in these patients. Future in vivo studies are warranted to determine the potential clinical use of intra colonic administration of L-ILE in CD patients. The observed antimicrobial activity of HBD2 against bacterial isolates provides evidence that it is a crucial component of mucosal epithelial defense against infections which can complicate disease symptoms in CD.

Introdução: A Doença da Urina do Xarope de Bordo é uma doença hereditária do metabolismo dos aminoácidos de cadeia ramificada, de caráter autossômico recessivo. O diagnóstico precoce é fundamental na prevenção da deterioração neurológica, que se dá pela ausência da implementação do tratamento nutricional adequado. Objetivo: Realizar triagem das mutações em todos os éxons dos três genes envolvidos na Doença da Urina do Xarope de Bordo (BCKDHA, BCKDHB e DBT) através do sequenciamento gênico direto e correlacionar com a heterogeneidade fenotípica. Métodos: Estudo clínico transversal com pacientes chilenos diagnosticados com Doença da Urina do Xarope de Bordo. A genotipagem foi realizada com produtos purificados de reação em cadeia da polimerase (PCR) de DNA.Foi realizada análise in silico das substituições de nucleotídeos através dos softwares MutPred® v1.2, Polyphen-2® - Polymorphism Phenotyping v2 e SIFT®. As características clínicas dos pacientes foram fornecidas pela equipe de nutrição do Instituto de Nutrição e Tecnologia da Universidade de Chile (INTA). Foi realizado um teste exato de Fisher no grupo de pacientes portadores da mutação mais prevalente na amostragem, a I214K com a intenção de avaliar o grau de correlação entre algumas variáveis clínicas e genéticas para verificar a possibilidade de se estabelecer uma relação fenótipo/genótipo. Resultados: Dos 18 pacientes 88% apresentaram mutação no gene BCKDHB, 1 pacientes 5% apresentou mutação no gene BCKDHA e 1 (5%) paciente apresentou mutação no gene DBT. Foram encontradas um total de 8 mutações na amostra e 4 novas mutações (50%). Não se pode afirmar que há correlação de nenhuma das variáveis clínicas com os genótipos encontrados nessa amostragem. Conclusão: Este estudo reportou 4 novas mutações em pacientes portadores de DXB na população chilena, o que pode ajudar em futuros diagnósticos genéticos da doença. Se a DXB fosse diagnosticada de forma mais rápida, na triagem neonatal, talvez fosse possível estabelecer uma relação genótipo-fenótipo de forma mais eficiente / Introduction: Maple Syrup Urine Disease (MSUD) is an autossomal recessive hereditary disease of the branched-chain amino acid metabolism. Early diagnosis is essential in preventing neurological deterioration, which occurs due to inadequate nutritional implametation treatment. Purpose: Screen mutations in all exons from the three genes involved in MSUD (BCKDHA, BCKDHB and DBT) through direct gene sequencing and correlation with phenotypic heterogeneity. Methods: A cross-sectional study with Chilean patients diagnosed with Maple Syrup Urine Disease. Genotyping was performed using purified polymerase chain reaction (PCR) DNA. Nucleotide substitutions In Silico analysis was performed using MutPred® v1.2, Polyphen-2® - Polymorphism Phenotyping v2 and SIFT® softwares. Patients clinical characteristics were provided by the nutrition team from Chile University, Nutriton and Technology Institute (INTA). Results: Of the 18 patients, 88% presented mutation in BCKDHB gene, 1 patient had mutation in BCKDHA gene and 1 patient (5%) presented a mutation in DBT gene. A total of 8 mutations in the sample and 4 new mutations (50%) were found. It can not be affirmed that there is correlation between clinical variables and genotypes in this sample. Conclusion: This study reported 4 new mutations in patients with MSUD in Chilean population, which may help in future genetic diagnosis. If MSUD was diagnosed more rapidly in neonatal screening, it might be possible to establish a genotype-phenotype relationship more efficiently

A doença de Chagas é uma doença negligenciada com aproximadamente 8 milhões de pessoas cronicamente infectadas e mais de 40 milhões sob risco de infecção. Atualmente as poucas drogas disponíveis para o tratamento da doença são limitadas em relação à eficácia e tolerância, o que evidencia a necessidade de novos alvos terapêuticos visando o desenvolvimento de drogas eficazes para o tratamento da doença. Estudos têm descrito a importância dos aminoácidos no ciclo de vida do T. cruzi, que além de atuarem na síntese proteica e no metabolismo energético, estão relacionados a diferentes funções no parasito. Apesar de estudos anteriores indicarem os aminoácidos de cadeia ramificada (BCAA - leucina, isoleucina e valina) como integrantes do metabolismo em T. cruzi é curioso o fato de ainda haver poucos estudos na literatura sobre a identificação de funções relevantes dos BCAA para a biologia do parasita, bem como associados a outros aminoácidos do T. cruzi. Esse projeto teve o propósito de: (1) Avaliar o papel biológico que os BCAA tem ao longo do ciclo de vida do parasita, com especial enfase nos processos de diferenciação, (2) Avaliar o transporte dos BCAA em T. cruzi. (2) Caracterizar cinéticamente se as enzimas transaminases tirosina aminotransferase TAT e aspartato aminotransferase ASAT catalisam a reação de desaminação/aminação dos derivados de BCAA. (3) Avaliar o papel funcional do complexo enzimático desidrogenase de alfa-cetoácidos ramificados BCAKDH. (4) Estudar a localização intracelular do complexo enzimático nas formas do parasita. (5) Avaliar os o potencial terapêutico. (6) Investigar a funcionalidade do mesmo e as proteinas associadas ao complexo enzimático BCAKDH. / Chagas disease is a neglected disease with approximately 8 million people chronically infected and more than 40 million at risk of infection. Currently the few drugs available for the treatment of the disease are limited in relation to efficacy and tolerance, which highlights the need for new therapeutic targets aimed at the development of drugs effective for the treatment of the disease. Studies have described the importance of amino acids in the life cycle of T. cruzi, which in addition to acting on protein synthesis and energetic metabolism, are related to different functions in the parasite. Although previous studies indicate branched chain amino acids (BCAA - leucine, isoleucine and valine) as components of metabolism in T. cruzi, it is curious that there are still few studies in the literature on the identification of relevant BCAA functions for the biology of parasite, as well as associated with other T. cruzi amino acids. The purpose of this project was to: (1) Evaluate the biological role of BCAAs in the life cycle of the parasite, with special emphasis on differentiation processes; (2) Evaluate BCAA transport in T. cruzi. (2) Kinetically characterize whether the enzymes transaminases tyrosine aminotransferase TAT and aspartate aminotransferase ASAT catalyze the deamination / amination reaction of the BCAA derivatives. (3) To evaluate the functional role of the enzymatic complex dehydrogenase of branched alpha-ketoacids BCAKDH. (4) To study the intracellular localization of the enzymatic complex in the forms of the parasite. (5) Evaluate the therapeutic potential. (6) Investigate the functionality of the proteins associated with the enzymatic complex BCAKDH.

A oviposição é um estágio vulnerável do ciclo de vida de carrapatos. Rhipicephalus microplus, como todos Ixodidae e Argasidae, possui uma glândula especializada, o órgão de Gené, que produz uma cera que é depositada na superfície do ovo durante a oviposição. Além de restringir a perda excessiva de água, a cera atua como uma barreira contra o ataque de organismos invasores. Em R.microplus, como em outros carrapatos, há poucos estudos demonstrando atividade antimicrobiana em ovos. Ainda mais, não há na literatura relato de atividade antibiofilme em ovos de carrapatos e nem mesmo em qualquer outro artrópode. O objetivo do presente trabalho foi avaliar a hipótese da existência de mecanismos de defesa em ovos de R. microplus contra biofilmes bacterianos. O extrato água/metanol da cera dos ovos apresentou atividade contra o biofilme de Pseudomonas aeruginosa sem afetar a sua viabilidade. Esse extrato também demonstrou efeito antibiótico contra Staphylococcus epidermidis. Nós identificamos a molécula com ambas atividades (antibiofilme e antibiótica) como N-(3-sulfooxy-25-cholest-5-en-26-oyl)-L-isoleucina (boophiline). Na busca por possíveis mecanismos responsáveis pelo efeito antibiofilme de boophiline contra P. aeruginosa, 14 genes foram analisados por qRT-PCR. Boophiline inibe a expressão de fliC (flagelo) e cdrA (componente estrutural da matriz), cujos produtos são necessários para a formação do biofilme de P. aeruginosa. Monosfosfato de guanosina dimérico cíclico (c-di-GMP) é um importante segundo mensageiro característico de bactérias Gram-negativas. Altos níveis intracelulares de c-di-GMP promovem o estilo de vida séssil enquanto baixos níveis induzem o comportamento móvel. De acordo com essa afirmação, nós encontramos que boophiline aumenta a motilidade swarming de P. aeruginosa. Desta forma, nos questionamos se o mecanismo de ação de boophiline estaria envolvido com c-di-GMP já que o sistema quorum sensing não foi afetado pela molécula. Interessantemente, quando os níveis de c-di-GMP foram aumentados pela superexpressão de uma diguanilato ciclase, boophiline não inibiu efetivamente a formação de biofilme. Uma explicação para esse resultado é que boophiline interfere em uma via específica regulada por c-di-GMP, o que explicaria não termos obtido um decréscimo no nível total deste segundo mensageiro. Contrariamente, boophiline foi bactericida contra S. epidermidis. Mudanças morfológicas significativas foram observadas em células tratadas com a molécula, as quais foram severamente danificadas. Boophiline levou a formação anormal de septo, rompimento da membrana bacteriana e extravasamento do material intracelular. Adicionalmente avaliamos o potencial antibiofilme e anti-protozoário de filtrados de cultura obtidos de bactérias isoladas de tecidos de R. microplus. Quatorze filtrados de cultura bacteriano apresentaram notável atividade contra o biofilme de P. aeruginosa e S. epidermidis e foram citotóxicos contra Tritrichomonas foetus. Nosso trabalho é pioneiro em demonstrar a existência de proteção contra biofilmes em ovos de carrapatos bem como de bactérias associadas a carrapatos como produtoras de moléculas bioativas. Além disso, nós demonstramos que boophiline é uma nova molécula antibiofilme, sendo a primeira vez relatado na literatura que um composto age inibindo cdrA. Os dados obtidos em nosso estudo poderiam estimular novas abordagens em áreas como fisiologia e controle de artrópodes, genética e fisiologia de microrganismos e controle de biofilmes. / The oviposition is a vulnerable stage of the tick life cycle. Rhipicephalus microplus, as all Ixodidae and Argasidae, has a specialized gland, the Gene’s organ, which produce a wax that is smeared on egg surface during oviposition. In addition to restricting excessive water loss, wax acts as a barrier to attack by invading organisms. In R. microplus, as in other ticks, there are few studies showing antimicrobial activity in eggs. Moreover, there is no report of antibiofilm activity in tick eggs nor in any other arthropod. The objective of our study was to evaluate the hypothesis of the existence of defense mechanisms against bacterial biofilms in R. microplus eggs. The eggs wax water/methanol extract showed activity against Pseudomonas aeruginosa biofilm without affecting its viability. This extract also presented an antibiotic effect against Staphylococcus epidermidis. We have identified the molecule anti-biofilm and antibiotic as N-(3-sulfooxy-25-cholest-5-en-26-oyl)-L-isoleucine (boophiline). In the search for possible mechanisms responsible by antibiofilm effect of boophiline against P. aeruginosa, 14 genes were evaluated by qRT-PCR. We showed that boophiline inhibits the expression of fliC (flagellum) and cdrA (matrix structural component), whose products are necessary for biofilm formation in P. aeruginosa. Bis-(3’–5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) is an important second messenger, characteristic of Gram-negative bacteria. High intracellular levels of c-di-GMP promote a sessile mode of growth, while low levels promote motile behavior. In line with this, we found that boophiline increases swarming motility, which raised the question whether it acts by altering c-di-GMP levels. Interestingly, when c-di-GMP levels were increased by overexpression of a diguanilate cyclase, boophiline no longer inhibited biofilm formation. One explanation for these results is that boophiline interferes with a specific c-di-GMP-regulated pathway, which would explain we have not obtained a decrease in the total level of this second messenger. Conversely, boophiline had a bactericidal effect against S. epidermidis. Significant morphological changes were observed in the boophiline-treated cells, which appeared to be severely damaged. Boophiline was found to cause abnormal septum formation, bacterial membrane disruption, and extravasation of intracellular material. Additionally, our work also aimed to evaluate the potential antibiofilm and anti-protozoa of culture filtrates obtained from bacteria isolated of R. microplus tissues. Fourteen bacterial culture filtrates showed remarkable activity against of P. aeruginosa and S. epidermidis biofilms, and were cytotoxic against Tritrichomonas foetus. Our work is pioneer in demonstrating the existence of protection mechanisms in tick eggs against biofilms, and ticks-associated bacteria as producers of bioactive molecules. Furthermore, we demonstrated that boophiline is a new antibiofilm molecule, and is the first reported in the literature that a molecule inhibits cdrA. The data obtained in our study could stimulate new approaches in areas such as the physiology and control of arthropods, the genetics and physiology of microorganisms, and biofilm control.

A oviposição é um estágio vulnerável do ciclo de vida de carrapatos. Rhipicephalus microplus, como todos Ixodidae e Argasidae, possui uma glândula especializada, o órgão de Gené, que produz uma cera que é depositada na superfície do ovo durante a oviposição. Além de restringir a perda excessiva de água, a cera atua como uma barreira contra o ataque de organismos invasores. Em R.microplus, como em outros carrapatos, há poucos estudos demonstrando atividade antimicrobiana em ovos. Ainda mais, não há na literatura relato de atividade antibiofilme em ovos de carrapatos e nem mesmo em qualquer outro artrópode. O objetivo do presente trabalho foi avaliar a hipótese da existência de mecanismos de defesa em ovos de R. microplus contra biofilmes bacterianos. O extrato água/metanol da cera dos ovos apresentou atividade contra o biofilme de Pseudomonas aeruginosa sem afetar a sua viabilidade. Esse extrato também demonstrou efeito antibiótico contra Staphylococcus epidermidis. Nós identificamos a molécula com ambas atividades (antibiofilme e antibiótica) como N-(3-sulfooxy-25-cholest-5-en-26-oyl)-L-isoleucina (boophiline). Na busca por possíveis mecanismos responsáveis pelo efeito antibiofilme de boophiline contra P. aeruginosa, 14 genes foram analisados por qRT-PCR. Boophiline inibe a expressão de fliC (flagelo) e cdrA (componente estrutural da matriz), cujos produtos são necessários para a formação do biofilme de P. aeruginosa. Monosfosfato de guanosina dimérico cíclico (c-di-GMP) é um importante segundo mensageiro característico de bactérias Gram-negativas. Altos níveis intracelulares de c-di-GMP promovem o estilo de vida séssil enquanto baixos níveis induzem o comportamento móvel. De acordo com essa afirmação, nós encontramos que boophiline aumenta a motilidade swarming de P. aeruginosa. Desta forma, nos questionamos se o mecanismo de ação de boophiline estaria envolvido com c-di-GMP já que o sistema quorum sensing não foi afetado pela molécula. Interessantemente, quando os níveis de c-di-GMP foram aumentados pela superexpressão de uma diguanilato ciclase, boophiline não inibiu efetivamente a formação de biofilme. Uma explicação para esse resultado é que boophiline interfere em uma via específica regulada por c-di-GMP, o que explicaria não termos obtido um decréscimo no nível total deste segundo mensageiro. Contrariamente, boophiline foi bactericida contra S. epidermidis. Mudanças morfológicas significativas foram observadas em células tratadas com a molécula, as quais foram severamente danificadas. Boophiline levou a formação anormal de septo, rompimento da membrana bacteriana e extravasamento do material intracelular. Adicionalmente avaliamos o potencial antibiofilme e anti-protozoário de filtrados de cultura obtidos de bactérias isoladas de tecidos de R. microplus. Quatorze filtrados de cultura bacteriano apresentaram notável atividade contra o biofilme de P. aeruginosa e S. epidermidis e foram citotóxicos contra Tritrichomonas foetus. Nosso trabalho é pioneiro em demonstrar a existência de proteção contra biofilmes em ovos de carrapatos bem como de bactérias associadas a carrapatos como produtoras de moléculas bioativas. Além disso, nós demonstramos que boophiline é uma nova molécula antibiofilme, sendo a primeira vez relatado na literatura que um composto age inibindo cdrA. Os dados obtidos em nosso estudo poderiam estimular novas abordagens em áreas como fisiologia e controle de artrópodes, genética e fisiologia de microrganismos e controle de biofilmes. / The oviposition is a vulnerable stage of the tick life cycle. Rhipicephalus microplus, as all Ixodidae and Argasidae, has a specialized gland, the Gene’s organ, which produce a wax that is smeared on egg surface during oviposition. In addition to restricting excessive water loss, wax acts as a barrier to attack by invading organisms. In R. microplus, as in other ticks, there are few studies showing antimicrobial activity in eggs. Moreover, there is no report of antibiofilm activity in tick eggs nor in any other arthropod. The objective of our study was to evaluate the hypothesis of the existence of defense mechanisms against bacterial biofilms in R. microplus eggs. The eggs wax water/methanol extract showed activity against Pseudomonas aeruginosa biofilm without affecting its viability. This extract also presented an antibiotic effect against Staphylococcus epidermidis. We have identified the molecule anti-biofilm and antibiotic as N-(3-sulfooxy-25-cholest-5-en-26-oyl)-L-isoleucine (boophiline). In the search for possible mechanisms responsible by antibiofilm effect of boophiline against P. aeruginosa, 14 genes were evaluated by qRT-PCR. We showed that boophiline inhibits the expression of fliC (flagellum) and cdrA (matrix structural component), whose products are necessary for biofilm formation in P. aeruginosa. Bis-(3’–5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) is an important second messenger, characteristic of Gram-negative bacteria. High intracellular levels of c-di-GMP promote a sessile mode of growth, while low levels promote motile behavior. In line with this, we found that boophiline increases swarming motility, which raised the question whether it acts by altering c-di-GMP levels. Interestingly, when c-di-GMP levels were increased by overexpression of a diguanilate cyclase, boophiline no longer inhibited biofilm formation. One explanation for these results is that boophiline interferes with a specific c-di-GMP-regulated pathway, which would explain we have not obtained a decrease in the total level of this second messenger. Conversely, boophiline had a bactericidal effect against S. epidermidis. Significant morphological changes were observed in the boophiline-treated cells, which appeared to be severely damaged. Boophiline was found to cause abnormal septum formation, bacterial membrane disruption, and extravasation of intracellular material. Additionally, our work also aimed to evaluate the potential antibiofilm and anti-protozoa of culture filtrates obtained from bacteria isolated of R. microplus tissues. Fourteen bacterial culture filtrates showed remarkable activity against of P. aeruginosa and S. epidermidis biofilms, and were cytotoxic against Tritrichomonas foetus. Our work is pioneer in demonstrating the existence of protection mechanisms in tick eggs against biofilms, and ticks-associated bacteria as producers of bioactive molecules. Furthermore, we demonstrated that boophiline is a new antibiofilm molecule, and is the first reported in the literature that a molecule inhibits cdrA. The data obtained in our study could stimulate new approaches in areas such as the physiology and control of arthropods, the genetics and physiology of microorganisms, and biofilm control.

A oviposição é um estágio vulnerável do ciclo de vida de carrapatos. Rhipicephalus microplus, como todos Ixodidae e Argasidae, possui uma glândula especializada, o órgão de Gené, que produz uma cera que é depositada na superfície do ovo durante a oviposição. Além de restringir a perda excessiva de água, a cera atua como uma barreira contra o ataque de organismos invasores. Em R.microplus, como em outros carrapatos, há poucos estudos demonstrando atividade antimicrobiana em ovos. Ainda mais, não há na literatura relato de atividade antibiofilme em ovos de carrapatos e nem mesmo em qualquer outro artrópode. O objetivo do presente trabalho foi avaliar a hipótese da existência de mecanismos de defesa em ovos de R. microplus contra biofilmes bacterianos. O extrato água/metanol da cera dos ovos apresentou atividade contra o biofilme de Pseudomonas aeruginosa sem afetar a sua viabilidade. Esse extrato também demonstrou efeito antibiótico contra Staphylococcus epidermidis. Nós identificamos a molécula com ambas atividades (antibiofilme e antibiótica) como N-(3-sulfooxy-25-cholest-5-en-26-oyl)-L-isoleucina (boophiline). Na busca por possíveis mecanismos responsáveis pelo efeito antibiofilme de boophiline contra P. aeruginosa, 14 genes foram analisados por qRT-PCR. Boophiline inibe a expressão de fliC (flagelo) e cdrA (componente estrutural da matriz), cujos produtos são necessários para a formação do biofilme de P. aeruginosa. Monosfosfato de guanosina dimérico cíclico (c-di-GMP) é um importante segundo mensageiro característico de bactérias Gram-negativas. Altos níveis intracelulares de c-di-GMP promovem o estilo de vida séssil enquanto baixos níveis induzem o comportamento móvel. De acordo com essa afirmação, nós encontramos que boophiline aumenta a motilidade swarming de P. aeruginosa. Desta forma, nos questionamos se o mecanismo de ação de boophiline estaria envolvido com c-di-GMP já que o sistema quorum sensing não foi afetado pela molécula. Interessantemente, quando os níveis de c-di-GMP foram aumentados pela superexpressão de uma diguanilato ciclase, boophiline não inibiu efetivamente a formação de biofilme. Uma explicação para esse resultado é que boophiline interfere em uma via específica regulada por c-di-GMP, o que explicaria não termos obtido um decréscimo no nível total deste segundo mensageiro. Contrariamente, boophiline foi bactericida contra S. epidermidis. Mudanças morfológicas significativas foram observadas em células tratadas com a molécula, as quais foram severamente danificadas. Boophiline levou a formação anormal de septo, rompimento da membrana bacteriana e extravasamento do material intracelular. Adicionalmente avaliamos o potencial antibiofilme e anti-protozoário de filtrados de cultura obtidos de bactérias isoladas de tecidos de R. microplus. Quatorze filtrados de cultura bacteriano apresentaram notável atividade contra o biofilme de P. aeruginosa e S. epidermidis e foram citotóxicos contra Tritrichomonas foetus. Nosso trabalho é pioneiro em demonstrar a existência de proteção contra biofilmes em ovos de carrapatos bem como de bactérias associadas a carrapatos como produtoras de moléculas bioativas. Além disso, nós demonstramos que boophiline é uma nova molécula antibiofilme, sendo a primeira vez relatado na literatura que um composto age inibindo cdrA. Os dados obtidos em nosso estudo poderiam estimular novas abordagens em áreas como fisiologia e controle de artrópodes, genética e fisiologia de microrganismos e controle de biofilmes. / The oviposition is a vulnerable stage of the tick life cycle. Rhipicephalus microplus, as all Ixodidae and Argasidae, has a specialized gland, the Gene’s organ, which produce a wax that is smeared on egg surface during oviposition. In addition to restricting excessive water loss, wax acts as a barrier to attack by invading organisms. In R. microplus, as in other ticks, there are few studies showing antimicrobial activity in eggs. Moreover, there is no report of antibiofilm activity in tick eggs nor in any other arthropod. The objective of our study was to evaluate the hypothesis of the existence of defense mechanisms against bacterial biofilms in R. microplus eggs. The eggs wax water/methanol extract showed activity against Pseudomonas aeruginosa biofilm without affecting its viability. This extract also presented an antibiotic effect against Staphylococcus epidermidis. We have identified the molecule anti-biofilm and antibiotic as N-(3-sulfooxy-25-cholest-5-en-26-oyl)-L-isoleucine (boophiline). In the search for possible mechanisms responsible by antibiofilm effect of boophiline against P. aeruginosa, 14 genes were evaluated by qRT-PCR. We showed that boophiline inhibits the expression of fliC (flagellum) and cdrA (matrix structural component), whose products are necessary for biofilm formation in P. aeruginosa. Bis-(3’–5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) is an important second messenger, characteristic of Gram-negative bacteria. High intracellular levels of c-di-GMP promote a sessile mode of growth, while low levels promote motile behavior. In line with this, we found that boophiline increases swarming motility, which raised the question whether it acts by altering c-di-GMP levels. Interestingly, when c-di-GMP levels were increased by overexpression of a diguanilate cyclase, boophiline no longer inhibited biofilm formation. One explanation for these results is that boophiline interferes with a specific c-di-GMP-regulated pathway, which would explain we have not obtained a decrease in the total level of this second messenger. Conversely, boophiline had a bactericidal effect against S. epidermidis. Significant morphological changes were observed in the boophiline-treated cells, which appeared to be severely damaged. Boophiline was found to cause abnormal septum formation, bacterial membrane disruption, and extravasation of intracellular material. Additionally, our work also aimed to evaluate the potential antibiofilm and anti-protozoa of culture filtrates obtained from bacteria isolated of R. microplus tissues. Fourteen bacterial culture filtrates showed remarkable activity against of P. aeruginosa and S. epidermidis biofilms, and were cytotoxic against Tritrichomonas foetus. Our work is pioneer in demonstrating the existence of protection mechanisms in tick eggs against biofilms, and ticks-associated bacteria as producers of bioactive molecules. Furthermore, we demonstrated that boophiline is a new antibiofilm molecule, and is the first reported in the literature that a molecule inhibits cdrA. The data obtained in our study could stimulate new approaches in areas such as the physiology and control of arthropods, the genetics and physiology of microorganisms, and biofilm control.

Herz-Kreislauf-Erkrankungen sind nach wie vor die häufigste Todesursache. Vor allem Bluthochdruck ist in diesem Zusammenhang ein wichtiger Risikofaktor für die Entstehung von koronaren Herzerkrankungen, Myokardinfarkten, Herzinsuffizienz und Schlaganfall. Zur Behandlung der Hypertonie werden unterschiedliche Pharmaka eingesetzt, hauptsächlich Substanzen, die das Renin-Angiotensin-Aldosteron-System (RAAS) hemmen. Dazu gehören synthetische Inhibitoren des angiotensin-converting enzyme (ACE). Für präventive Zwecke können diese ACE-Inhibitoren auf Grund mehrerer Nebenwirkungen nicht eingesetzt werden. Interessant für eine präventive Anwendung sind natürliche ACE-hemmende Peptide, welche in der Sequenz unterschiedlicher Lebensmittelproteine vorliegen und durch enzymatische Hydrolyse freigesetzt werden. Ein besonders potenter ACE-Hemmer ist das Dipeptid Isoleucin-Tryptophan (IW) und damit ein interessanter Kandidat für den Einsatz in einem funktionellen Lebensmittel. Um dies jedoch realisieren zu können, muss IW in einer ausreichenden Menge produziert werden. Durch die enzymatische Hydrolyse ist dies aktuell nicht möglich, da die Peptidsequenz IW sehr selten in Proteinen vorhanden ist. Aus diesem Grund war es Ziel der vorliegenden Arbeit eine innovative biotechnologische Methode zu etablieren, um das ACE-hemmende Dipeptid IW in höheren Mengen und vor allem lebensmittelkonform zu produzieren. Die Produktion des ACE-hemmenden Peptids wurde biotechnologisch mittels rekombinanter DNA-Technologie realisiert. Hierfür wurde eine repetitive IW-Sequenz entworfen (264 bp), welche für ein 10 kDa großes Protein codierte. Dieses IW-Konstrukt enthielt in der Sequenz 16-mal IW. Mit Hilfe von Escherichia coli (E. coli) wurde ein 52 kDa großes Fusionsprotein überexprimiert. Als Fusionstag diente das Maltose Binding Protein (MBP). Dieses rekombinante Fusionsprotein (MBP-IW) lag nach einer Kombination von zwei verschiedenen chromatographischen Verfahren gereinigt vor. Mit dieser Methode war es möglich, 0,52 mg lösliches MBP-IW pro 1 g E. coli Feuchtmasse zu produzieren. MBP-IW wurde enzymatisch mit dem Enzym α-Chymotrypsin hydrolisiert und das Dipeptid IW anschließend chromatographisch isoliert. Nach der Hydrolyse und Isolation lag die Ausbeute des rekombinant produzierten IW (rIW) mit einer Reinheit von ≥ 96 % bei 14 µg. Somit konnten 28 % des möglichen Anteils an rIW vom sauberen MBP-IW gewonnen werden. Die Identifikation von IW erfolgte mit drei unterschiedlichen Methoden, der reversed phase-high performance liquid chromatography-UV-Detektion, der liquid chromatography-electrospray ionisation-tandem mass spectrometry und durch eine N-terminale Derivatisierung des Peptids. Mit diesen Methoden wurde bestätigt, dass es sich bei dem produzierten Peptid um IW handelte. Das rIW wurde im Vergleich zum chemisch produzierten kommerziell erwerblichen L-IW (cIW) und chemisch produzierten kommerziell erwerblichen D-IW (cDIW) auf sein ACE-hemmendes Potential getestet. Um der komplexen und heterogenen Verteilung der ACE-Aktivität im menschlichen Organismus gerecht zu werden, wurde das ACE-hemmende Potential der Dipeptide an verschiedenen ACE-Quellen untersucht. Neben dem nicht-humanen ACE-System (ACE aus der Kaninchenlunge) wurde auch humanes lösliches ACE (aus humanem Plasma) sowie humanes membrangebundenes ACE (aus Human umbilical vein endothelial cells, HUVECs) verwendet. Bei allen getesteten ACE-Systemen zeigte sich kein ACE-hemmendes Potential durch cDIW. Beim Vergleich von rIW mit cIW in Bezug auf deren ACE-hemmendes Potential wurden IC50-Werte von 1,72 ± 0,12 bis 23,30 ± 3,68 µM, abhängig vom getesteten ACE-System, bestimmt. Für alle verwendeten ACE-Quellen konnte gezeigt werden, dass beide unterschiedlich produzierten Dipeptide gleich effektiv waren. Ein weiteres Ziel der Arbeit bestand darin neben einem Peptidmix aus Molkenprotein mit hohem Anteil an IW, noch zwei weitere Peptidmixe pflanzlichen Proteinursprungs hinsichtlich des ACE-hemmenden Potentials zu untersuchen. Auf Grundlage der identifizierten tryptophan- und tyrosinhaltigen Dipeptide in den Hydrolysaten des Molken-, Soja- und Reisproteins wurden drei Peptidmixe hergestellt. Auch hier wurde wieder die Wirkung auf mehrere ACE-Quellen ermittelt. Neben den oben genannten, wurde hier zusätzlich der Einfluss auf membrangebundenes ACE der Rattenaorta untersucht. In allen getesteten ACE-Systemen zeigte der Peptidmix Molke ein signifikant höheres ACE-hemmendes Potential als die Peptidmixe von Soja und Reis. Der Peptidmix Soja war von den getesteten hydrolisierten Pflanzenproteinen der potenteste ACE-Inhibitor. Die IC50-Werte der Peptidmixe lagen, je nach getestetem ACE-System, zwischen 16,60 ± 2,59 und 282,04 ± 18,51 mg/l. Der starke ACE-hemmende Effekt vom Peptidmix Molke wurde mit der hohen Konzentration an IW assoziiert (bis zu 10-fach höher verglichen mit den anderen beiden Peptidmixen). Dies legt nahe, dass das Dipeptid IW hauptverantwortlich für das ACE-hemmende Potential in den getesteten Peptidmixen ist, was nochmals das große Potential des Dipeptids verdeutlicht. Im Rahmen dieser Arbeit konnte gezeigt werden, dass IW aus Molkenprotein im Vergleich mit den bioaktiven Peptidquellen der Proteine aus Soja und Reis, die stärkste ACE-Hemmung aufweist. Des Weiteren ist es erstmals gelungen, das ACE-hemmende Dipeptid IW in hoher Reinheit biotechnologisch mit Hilfe von rekombinanten Proteinen herzustellen. Um den Einsatz als funktionelles Lebensmittel realisieren zu können, müsste im Weiteren die biotechnologische Herstellung von IW optimiert werden, um eine höhere Ausbeute zu generieren. Nach dieser Optimierung könnte in einem Scale-up Verfahren so viel an IW gewonnen werden, dass es industriell einsetzbar wäre. Die ACE-hemmende Wirkung des biotechnologisch hergestellten IWs wurde in dieser Arbeit bestätigt, sodass es in einem innovativen funktionellen Lebensmittel für die tägliche Ernährung eingesetzt werden könnte. Perspektivisch eröffnet sich damit die Möglichkeit IW präventiv zu nutzen, um die Entwicklung von Bluthochdruck und deren Folgeschädigungen zu verzögern oder zu minimieren. / Cardiovascular diseases are still the leading cause of death. Especially hypertension is an important risk factor for the development of coronary heart disease, myocardial infarction, heart failure and stroke. To treat hypertension different drugs are clinically used. This are mainly substances, which inhibit the renin-angiotensin-aldosterone-system (RAAS), such as synthetic inhibitors of angiotensin-converting enzyme (ACE). However these ACE-inhibitors cannot be used for preventive purposes because of several side effects. Therefore natural ACE-inhibitory peptides, which are mostly encrypted in food proteins and released by enzymatic hydrolysis, are of main interest for preventive applications. The dipeptide isoleucine-tryptophan (IW) is a potent ACE-inhibitor and thus an interesting ingredient in functional foods. However, to realize this, IW must be produced in sufficient amounts. This is not possible with the current enzymatic hydrolysis, because the peptide sequence of IW is very rarely present in proteins. For that reason, the aim of the present thesis was to establish an innovative biotechnological method to produce the ACE-inhibitory dipeptide IW in an enlarged amount and especially considering the food-safety. The production of the ACE-inhibitory peptide was realized biotechnologically via recombinant DNA technology. For this, a repetitive IW-sequence (264 bp) was designed, which encoded a 10 kDa protein. In this IW-construct IW was sequenced 16 times. Using Escherichia coli (E. coli) a fusion protein with a size of 52 kDa was overexpressed. The maltose binding protein (MBP) served as fusion tag. This recombinant fusion protein (MBP-IW) was purified by a combination of two different chromatographic methods. It has become possible to produce 0.52 mg of soluble MBP-IW per 1 g wet weight of E. coli. MBP-IW was enzymatically hydrolysed with the enzyme α-chymotrypsin and the dipeptide IW was subsequently isolated by chromatography. After hydrolysis and isolation, the yield of the recombinant produced IW (rIW) with a purity of ≥ 96 % was 14 μg. Thus, 28 % from the possible content of rIW was obtained from the clean MBP-IW. IW was identified by three different methods: reversed phase-high performance liquid chromatography with UV-detection, liquid chromatography-electrospray ionisation-tandem mass spectrometry and N-terminal derivatization of the peptide. These methods confirmed the produced peptide as IW. The ACE-inhibitory potential of rIW was analysed and compared to that of the chemically produced commercially available L-IW (cIW) and of the chemically produced commercially available D-IW (cDIW). To address the complex and heterogeneous distribution of ACE-activity in the human organism, the ACE-inhibitory potential of the dipeptides was investigated in different ACE-sources. Additionally to non-human ACE (from rabbit lung) also human soluble ACE (from human plasma) and human membrane-bound ACE (from human umbilical vein endothelial cells, HUVECs) were used. In all tested ACE-systems cDIW did not show any ACE-inhibitory effect. IC50 values of rIW and cIW ranged from 1.72 ± 0.12 to 23.30 ± 3.68 μM, depending on the investigated ACE-system. In all sources of ACE an equal inhibitory potency of both differently produced dipeptides were determined. The second aim of the thesis was to investigate the ACE-inhibitory effect of two peptide mixes of plant proteins beside the peptide mix of whey protein, containing a high concentration of IW. Based on the identified tryptophan- and tyrosine-containing dipeptides in the hydrolysates of the whey-, soy- and rice-protein, three peptide mixes were prepared. Also here the effect on different ACE-sources was determined. Additionally to the named above, membrane-bound ACE from rat aorta was investigated. In all analysed ACE-systems, the peptide mix of whey showed a significantly higher ACE-inhibitory potential than the peptide mixes of soy and rice. The peptide mix soy was the most potent ACE-inhibitor tested among the hydrolysed plant proteins. The IC50-values of the peptide mixes were between 16.60 ± 2.59 and 282.04 ± 18.51 mg/l, depending on the used ACE-system. The strong ACE-inhibitory effect of the whey peptide mix was associated with the high concentration of IW (10 times higher compared to the other peptide mixes). This indicates that the dipeptide IW is mainly responsible for the ACE-inhibitory potential in the investigated peptide mixes, which demonstrate again the great potential of this dipeptide. It was shown in the present study that IW from whey protein had the strongest ACE-inhibition compared to the bioactive peptides of proteins from soy and rice. Furthermore, for the first time it was possible to produce the ACE-inhibitory dipeptide IW in high purity biotechnologically using recombinant proteins. To use IW as an ingredient in functional foods, the biotechnological production of IW needs to be optimized to receive higher yields. After this optimization, it would be conceivable to increase the production of IW in a scale-up process for industrial application. The ACE-inhibitory effect of the biotechnologically produced IW was confirmed in the present study, thus it could be used in an innovative functional food for daily nutrition. Prospectively, this increases the possibility of using IW preventively in order to delay or minimize the development of hypertension and the consequentially diseases.