OXIDATIVE CHANGES OF LIPIDS, PROTEINS AND ANTIOXIDANTS IN YOGURT DURING THE SHELF LIFE

Background: Oxidation processes in milk and yogurt during the shelf life can result in an alteration of protein and lipid constituents. Therefore, the antioxidant properties of yogurt in standard conditions of preservation were evaluated. Results: Total phenols, free radical scavenger activity, degree of lipid peroxidation and protein oxidation were determined in plain and skim yogurts with or without fruit puree. After production, plain, skim, plain berries and skim berries yogurts were compared during the shelf life up to 9 weeks. All types of yogurts revealed a basal antioxidant activity that was higher when a fruit puree was present but gradually decreased during the shelf life. However, after five-eight weeks, antioxidant activity increased again. Both in plain and berries yogurts lipid peroxidation increased until the seventh week of shelf life and after decreased, while protein oxidation of all yogurts was similar either in the absence or presence of berries and increased during shelf life. Conclusion: During the shelf life, a different behavior between lipid and protein oxidation takes place and the presence of berries determines a protection only against lipid peroxidation

Mitochondrial Thioredoxin System as a Modulator of Cyclophilin D Redox State

The mitochondrial thioredoxin system (NADPH, thioredoxin reductase, thioredoxin) is a major redox regulator. Here we have investigated the redox correlation between this system and the mitochondrial enzyme cyclophilin D. The peptidyl prolyl cis-trans isomerase activity of cyclophilin D was stimulated by the thioredoxin system, while it was decreased by cyclosporin A and the thioredoxin reductase inhibitor auranofin. The redox state of cyclophilin D, thioredoxin 1 and 2 and peroxiredoxin 3 was measured in isolated rat heart mitochondria and in tumor cell lines (CEM-R and HeLa) by redox Western blot analysis upon inhibition of thioredoxin reductase with auranofin, arsenic trioxide, 1-chloro-2,4-dinitrobenzene or after treatment with hydrogen peroxide. A concomitant oxidation of thioredoxin, peroxiredoxin and cyclophilin D was observed, suggesting a redox communication between the thioredoxin system and cyclophilin. This correlation was further confirmed by i) co-immunoprecipitation assay of cyclophilin D with thioredoxin 2 and peroxiredoxin 3, ii) molecular modeling and iii) depleting thioredoxin reductase by siRNA. We conclude that the mitochondrial thioredoxin system controls the redox state of cyclophilin D which, in turn, may act as a regulator of several processes including ROS production and pro-apoptotic factors release

Produção científica da linha epistemologia ambiental do Programa de Pós-Graduação em Meio Ambiente e Desenvolvimento - UFPR

Orientador: Prof. Dr. Roberto Gonçalves BarbosaCoorientador: Profa. Dra. Maria do Rosário KnechtelDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Agrárias, Programa de Pós-Graduação em Meio Ambiente e Desenvolvimento. Defesa : Curitiba, 04/10/2022Inclui referências: p. 173-176Resumo: Esta dissertação tem como tema geral ou objeto de pesquisa, a produção científica da linha de pesquisa Epistemologia Ambiental do Programa de Pós-graduação em Meio Ambiente e Desenvolvimento da Universidade Federal do Paraná. A hipótese que orienta o trabalho é de que, apesar de ser uma área ainda recente, a Epistemologia Ambiental oferece uma produção plurívoca, integrada e consistente, concorrendo para o desenvolvimento do campo da Epistemologia Ambiental e suas categorias. Nesse sentido questiona-se: uma visão de conjunto da produção acadêmica em Epistemologia Ambiental já é capaz de revelar um campo articulado e coerente de conhecimentos? Para a pesquisa, fundamentada na integração da epistemologia clássica e da epistemologia ambiental, foi selecionado o conjunto de Dissertações e Teses produzidas na Linha de Pesquisa Epistemologia Ambiental do Programa de Pós-Graduação em Meio Ambiente e Desenvolvimento da Universidade Federal do Paraná, defendidas de 2012 a 2022, vez que se trata de Linha específica ao tema. Metodologicamente, adotou-se o Estado de Conhecimento, com ênfase em três eixos: referências bibliográficas, categorias epistemológicas e resumos. Os procedimentos derivados, foram: inventário descritivo, sistematização de dados a partir de fonte primária e análise documental quanti-qualitativa. O objetivo geral da pesquisa foi estabelecer características específicas da produção científica, no âmbito da seleção estabelecida. Como objetivos específicos definiram-se: reunir informações e dados sobre as produções científicas da seleção, para fins de construção de uma base de dados; analisar os dados coletados para a definição de tendências temáticas, teórico-epistemológicas e metodológicas contidas na seleção; fornecer uma visão de conjunto da produção em Epistemologia Ambiental, na seleção proposta, como contribuição aos interessados no tema. Os resultados obtidos foram: consolidação de um banco de dados da produção acadêmica - dissertações e teses - do PPGMADE/UFPR; análises quanti-qualitativas sobre o conjunto de referências bibliográficas constantes em cada dissertação e tese; análises quanti-qualitativas sobre as categorias epistemológicas no corpo dos textos da seleção; análises comparativo-qualitativas das categorias da tipologia textual resumo em cada dissertação e tese. Concluiu-se que a seleção pesquisada apresentou uma quantidade rica de autores referidos, com tendência à dispersão, preponderando uma única referência por autor(a); houve escassa referência a pensadores clássicos da epistemologia, salvo raras menções a Descartes, Galileu e Bacon; quanto às categorias epistemológicas, foram identificadas 89, preponderando seis que receberam mais de mil menções no corpo dos textos da seleção; os resumos apresentam lacunas especialmente nas categorias "problema", "hipótese" e "fundamentação epistemológica"; também houve casos de incoerência entre "objetivos" propostos e os "resultados/conclusões" alcançados; algumas produções não referiram nem possibilitaram inferir categorias obrigatórias como é o caso da categoria "conclusão"; quanto à contribuição da Linha para o desenvolvimento da Epistemologia Ambiental, constatou-se apenas uma tese de cunho efetivamente epistemológico, vez que as outras produções caracterizam-se como pesquisa aplicada a outros campos, especialmente Legislação (seis ocorrências) e Educação (duas ocorrências).Abstract: This dissertation has as general theme or object of research, the scientific production of the Environmental Epistemology research line of the Graduate Program in Environment and Development at the Federal University of Paraná. The hypothesis that guides the work is that despite being a recent area, Environmental Epistemology offers a plurivocal, integrated and consistent production, contributing to the development of the field of Environmental Epistemology and its categories. In this sense, the following question arises: is an overall view of academic production in Environmental Epistemology capable of revealing an articulated and coherent field of knowledge? For the research, based on the integration of classical epistemology and environmental epistemology, the set of Dissertations and Theses produced in the Environmental Epistemology Research Line of the Graduate Program in Environment and Development of the Federal University of Paraná, defended in 2012 was selected to 2022, as it is a topic-specific line. Methodologically, the State of Knowledge was adopted, with emphasis on three axes: bibliographical references, epistemological categories and abstracts. Derived procedures were: descriptive inventory, systematization of data from a primary source and quantitative and qualitative document analysis. The general objective of the research was to establish specific characteristics of scientific production, within the scope of the established selection. As specific objectives were defined: to gather information and data on the scientific productions of the selection, for the purpose of building a database; to analyze the collected data for the definition of thematic, theoretical-epistemological and methodological tendencies contained in the selection; provide an overview of production in Environmental Epistemology, in the proposed selection, as a contribution to those interested in the theme. The results obtained were: consolidation of a database of academic production - dissertations and theses - from PPGMADE/UFPR; quantitative and qualitative analyzes on the set of bibliographical references contained in each dissertation and thesis; quantitative and qualitative analyzes of the epistemological categories in the body of selected texts; comparative-qualitative analyzes of the abstract textual typology categories in each dissertation and thesis. It was concluded that the researched selection presented a rich amount of referred authors, with a tendency to dispersion, with a predominance of a single reference per author; there was little reference to classical thinkers of epistemology, except for rare mentions of Descartes, Galileo and Bacon; as for the epistemological categories, 89 were identified, with a predominance of six that received more than a thousand mentions in the body of the texts of the selection; the abstracts show gaps especially in the categories "problem", "hypothesis" and "epistemological foundation"; there were also cases of inconsistency between the proposed "objectives" and the "results/conclusions" reached; some productions did not mention or make it possible to infer mandatory categories, such as the category "conclusion"; As for the Line's contribution to the development of Environmental Epistemology, there was only one thesis of an effectively epistemological nature, since the other productions are characterized as research applied to other fields, especially Legislation (six occurrences) and Education (two occurrences)

Dimers of Glutaredoxin 2 as Mitochondrial Redox Sensors in Selenite-induced Oxidative Stress

Glutaredoxin 2 (Grx2) has been previously shown to link thioredoxin and glutathione systems by receiving reducing equivalents by both thioredoxin reductase and glutathione. Grx2 catalyzes protein glutathionylation/deglutathionylation and can coordinate an iron-sulfur cluster, forming inactive dimers stabilized by two molecules of glutathione. This protein is mainly located in the mitochondrial matrix, though other isoforms have been found in the cytosolic and nuclear cell compartments. In the present study, we have analyzed the monomeric and dimeric states of Grx2 under different redox conditions in HeLa cells, and sodium selenite was utilized as the principal oxidizing agent. After selenite treatment, an increased glutathione oxidation was associated to Grx2 monomerization and activation, specifically in the mitochondrial compartment. Interestingly, in mitochondria, a large decline of thioredoxin reductase activity was also observed concomitantly to Grx2 activity stimulation. In addition, Grx2 monomerization led to an increase free iron ions concentration in the mitochondrial matrix, induction of lipid peroxidation and decrease of the mitochondrial membrane potential, indicating that the disassembly of Grx2 dimer involved the release of the iron-sulfur cluster in the mitochondrial matrix. Moreover, sodium selenite-triggered lipid and protein oxidation was partially prevented by deferiprone, an iron chelator with mitochondriotropic properties, suggesting a role of the iron-sulfur cluster release in the observed impairment of mitochondrial functions. Thus, by sensing the overall cellular redox conditions, mitochondrial Grx2 dimers become active monomers upon oxidative stress induced by sodium selenite with the consequent release of the iron-sulfur cluster, leading to activation of the intrinsic apoptotic pathway

Tamoxifen-like metallocifens target thioredoxin system determining mitochondrial impairment leading to apoptosis in Jurkat cells

Tamoxifen-like metallocifens (TLMs) of the group-8 metals (Fe, Ru, and Os) show strong anti-proliferative activity on cancer cell lines resistant to apoptosis, owing to their unique redox properties. In contrast, the thioredoxin system, which is involved in cellular redox balance, is often overexpressed in cancer cells, especially in tumour types resistant to standard chemotherapies. Therefore, we investigated the effect of these three TLMs on the thioredoxin system and evaluated the input of the metallocene unit in comparison with structurally related organic tamoxifens. In vitro, all three TLMs became strong inhibitors of the cytosolic (TrxR1) and mitochondrial (TrxR2) isoforms of thioredoxin reductase after enzymatic oxidation with HRP/H2O2 while none of the organic analogues was effective. In Jurkat cells, TLMs inhibited mainly TrxR2, resulting in the accumulation of oxidized thioredoxin 2 and cell redox imbalance. Overproduction of ROS resulted in a strong decrease in the mitochondrial membrane potential, translocation of cytochrome c to the cytosol and activation of caspase 3, thus leading to apoptosis. None of these events occurred with organic tamoxifens. The mitochondrial fraction of cells exposed to TLMs contained a high amount of the corresponding metal, as quantified by ICP-OES. The lipophilic and cationic character associated with the singular redox properties of the TLMs could explain why they alter the mitochondrial function. These results provide new insights into the mechanism of action of tamoxifen-like metallocifens, underlying their prodrug behaviour and the pivotal role played by the metallocenic entity in their cytotoxic activity associated with the induction of apoptosis

Milk-derived bioactive peptides exhibit antioxidant activity through the Keap1-Nrf2 signaling pathway

Bioactive peptides are relevant nutritional factors that exhibit many functions including antioxidant, anti-hypertensive, anticancer and antimicrobial properties. In this paper, four synthetic peptides ARHPHPHLSFM (A-11-M), AVPYPQR (A-7-R), NPYVPR (N-6-R) and KVLPVPEK (K-8-K) with sequences present in milk proteinswere examined for their antioxidant properties. The compounds show moderate free radical scavenging activityin the ABTS and crocin assays (A-7-R and N-6-R) and lipid peroxidation inhibition in Caco-2 cells (N-6-R and K-8-K). All peptides, in particular K-8-K, activate the Keap1-Nrf2 system by allowing the translocation of the tran-scription factor Nrf2 from the cytosol to nucleus. This activation triggers the overexpression of the antioxidantenzymes Trx1, TrxR1, GR, NQO1 and SOD1. Furthermore, molecular modeling shows that K-8-K is able to hinderthe interaction of Nrf2 with Keap1. The reported results show that the antioxidant action in cells of thesebioactive peptides is mostly due to the activation of Keap1-Nrf2 signaling pathwa

Milk-derived bioactive peptides exhibit antioxidant activity through the Keap1-Nrf2 signaling pathway

Abstract Bioactive peptides are relevant nutritional factors that exhibit many functions including antioxidant, antihypertensive, anticancer and antimicrobial properties. In this paper, four synthetic peptides ARHPHPHLSFM (A-11-M), AVPYPQR (A-7-R), NPYVPR (N-6-R) and KVLPVPEK (K-8-K) with sequences present in milk proteins were examined for their antioxidant properties. The compounds show moderate free radical scavenging activity in the ABTS and crocin assays (A-7-R and N-6-R) and lipid peroxidation inhibition in Caco-2 cells (N-6-R and K-8-K). All peptides, in particular K-8-K, activate the Keap1-Nrf2 system by allowing the translocation of the transcription factor Nrf2 from the cytosol to nucleus. This activation triggers the overexpression of the antioxidant enzymes Trx1, TrxR1, GR, NQO1 and SOD1. Furthermore, molecular modeling shows that K-8-K is able to hinder the interaction of Nrf2 with Keap1. The reported results show that the antioxidant action in cells of these bioactive peptides is mostly due to the activation of Keap1-Nrf2 signaling pathway