The mechanism of action of antimicrobial peptides : lipid vesicles vs. bacteria

Copyright © 2012 Melo and Castanho. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.The authors acknowledge the European FP7-PEOPLE-2009-IEF-254559 grant to Manuel N. Melo and the Fundação para a Ciência e a Tecnologia (Portugal) project PTDC/QUI-BIQ/112929/2009

Pharmaceutical innovations: the grand challenges ahead

Copyright © 2020 Aroeira and Castanho. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.Lifestyles are evolving rapidly due to swiftly evolving technologies rapid exchange of information across the globe, and facilitated mobility of people across long distances. In addition, climate changes accelerate the geographical dynamics of disease. The result is that both communicable and non-communicable diseases pose challenges never faced before and the perception of the way pharmaceutical sciences are dealing with such changes is under unprecedented scrutiny. The discredit in science-based solutions has a tremendous societal impact and is detrimental to evidence-based pharmacology at large. Pharmaceutical innovation that target the needs of healthy living and meet the expectation of society are urgently needed and are a worthy effect of both industrial and academic researchers. A reflection on the grand challenges ahead in thus timely and appropriate.This work was supported by La Caixa Foundation (grant reference: IMM/BPD/107-2018 to RA).info:eu-repo/semantics/publishedVersio

Anticancer peptides : prospective innovation in cancer therapy

© Springer International Publishing Switzerland 2016Current cancer treatments require improvements in selectivity and efficacy. Surgery, radiation, and chemotherapy approaches result in patient’s suffering over time due to the development of severe side-effects that simultaneously condition adherence to therapy. Biologically active peptides, in particular antimicrobial peptides (AMPs), are versatile molecules in terms of biological activities. The cytotoxic activities of several AMPs turn this group of molecules into an amazing pool of new templates for anticancer drug development. However, several unmet challenges limit application of peptides in cancer therapy. The mechanism(s) of action of the peptides need better description and understanding, and innovative targets have to be discovered and explored, facilitating drug design and development. In this chapter, we explore the natural occurring AMPs as potential new anticancer peptides (ACPs) for cancer prevention and treatment. Their modes of action, selectivity to tumor compared to normal cells, preferential targets, and applications, but also their weaknesses, are described and discussed.info:eu-repo/semantics/publishedVersio

The use of antibody-antibiotic conjugates to fight bacterial infections

Copyright © 2022 Cavaco, Castanho and Neves. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.The emergence of antimicrobial resistance (AMR) is rapidly increasing and it is one of the significant twenty-first century’s healthcare challenges. Unfortunately, the development of effective antimicrobial agents is a much slower and complex process compared to the spread of AMR. Consequently, the current options in the treatment of AMR are limited. One of the main alternatives to conventional antibiotics is the use of antibodyantibiotic conjugates (AACs). These innovative bioengineered agents take advantage of the selectivity, favorable pharmacokinetic (PK), and safety of antibodies, allowing the administration of more potent antibiotics with less off-target effects. Although AACs’ development is challenging due to the complexity of the three components, namely, the antibody, the antibiotic, and the linker, some successful examples are currently under clinical studies.The project leading to these results has received funding from “la Caixa” Foundation (ID 100010434), under the agreement LCF/PR/HR17/52150011 and from Portuguese Funding Agency, Fundação para a Ciência e Tecnologia (FCT IP, grants PD/BD/128281/2017 and DL 7/2016/CP1451/CT0023).info:eu-repo/semantics/publishedVersio

Resazurin reduction-based assays revisited: guidelines for accurate reporting of relative differences on metabolic status

© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Cell viability and metabolic activity are ubiquitous parameters used in biochemistry, molecular biology, and biotechnological studies. Virtually all toxicology and pharmacological projects include at some point the evaluation of cell viability and/or metabolic activity. Among the methods used to address cell metabolic activity, resazurin reduction is probably the most common. At variance with resazurin, resorufin is intrinsically fluorescent, which simplifies its detection. Resazurin conversion to resorufin in the presence of cells is used as a reporter of metabolic activity of cells and can be detected by a simple fluorometric assay. UV–Vis absorbance is an alternative technique but is not as sensitive. In contrast to its wide empirical “black box” use, the chemical and cell biology fundamentals of the resazurin assay are underexplored. Resorufin is further converted to other species, which jeopardizes the linearity of the assays, and the interference of extracellular processes has to be accounted for when quantitative bioassays are aimed at. In this work, we revisit the fundamentals of metabolic activity assays based on the reduction of resazurin. Deviation to linearity both in calibration and kinetics, as well as the existence of competing reactions for resazurin and resorufin and their impact on the outcome of the assay, are addressed. In brief, fluorometric ratio assays using low resazurin concentrations obtained from data collected at short time intervals are proposed to ensure reliable conclusions.The project leading to these results has received funding from “la Caixa” Foundation and FCT, I.P. under the project code [LCF/PR/HR21/00605], BREAST-BRAIN-N-BBB.info:eu-repo/semantics/publishedVersio

Translocating the blood-brain barrier using electrostatics

Copyright © 2012 Ribeiro,Domingues, Freire,Santos and Castanho. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in other forums, provided the original authors and source are credited and subject to any copyright notices concerning any third-party graphics etc.Mammalian cell membranes regulate homeostasis, protein activity, and cell signaling. The charge at the membrane surface has been correlated with these key events. Although mammalian cells are known to be slightly anionic, quantitative information on the membrane charge and the importance of electrostatic interactions in pharmacokinetics and pharmacodynamics remain elusive. Recently, we reported for the first time that brain endothelial cells (EC) are more negatively charged than human umbilical cord cells, using zeta-potential measurements by dynamic light scattering. Here, we hypothesize that anionicity is a key feature of the blood-brain barrier (BBB) and contributes to select which compounds cross into the brain. For the sake of comparison, we also studied the membrane surface charge of blood components—red blood cells (RBC), platelets, and peripheral blood mononuclear cells (PBMC).To further quantitatively correlate the negative zeta-potential values with membrane charge density, model membranes with different percentages of anionic lipids were also evaluated. From all the cells tested, brain cell membranes are the most anionic and those having their lipids mostly exposed, which explains why lipophilic cationic compounds are more prone to cross the blood-brain barrier.Fundação para a Ciência e Tecnologia — Ministério da Educação e Ciência (FCT-MEC, Portugal) is acknowledged for funding (including fellowships SFRH/BD/42158/2007 to Marta M.B. Ribeiro, SFRH/BD/41750/2007 to Marco M. Domingues and SFRH/BD/70423/2010 to João M. Freire) and project PTDC/QUI-BIQ/119509/2010. Marie Curie Industry-Academia Partnerships and Pathways (European Commission) is also acknowledged for funding (FP7-PEOPLE-2007-3-1-IAPP, Project 230654)

From antimicrobial to anticancer peptides : a review

Antimicrobial peptides (AMPs) are part of the innate immune defense mechanism of many organisms. Although AMPs have been essentially studied and developed as potential alternatives for fighting infectious diseases, their use as anticancer peptides (ACPs) in cancer therapy either alone or in combination with other conventional drugs has been regarded as a therapeutic strategy to explore. As human cancer remains a cause of high morbidity and mortality worldwide, an urgent need of new, selective, and more efficient drugs is evident. Even though ACPs are expected to be selective toward tumor cells without impairing the normal body physiological functions, the development of a selective ACP has been a challenge. It is not yet possible to predict antitumor activity based on ACPs structures. ACPs are unique molecules when compared to the actual chemotherapeutic arsenal available for cancer treatment and display a variety of modes of action which in some types of cancer seem to co-exist. Regardless the debate surrounding the definition of structure-activity relationships for ACPs, great effort has been invested in ACP design and the challenge of improving effective killing of tumor cells remains. As detailed studies on ACPs mechanisms of action are crucial for optimizing drug development, in this review we provide an overview of the literature concerning peptides' structure, modes of action, selectivity, and efficacy and also summarize some of the many ACPs studied and/or developed for targeting different solid and hematologic malignancies with special emphasis on the first group. Strategies described for drug development and for increasing peptide selectivity toward specific cells while reducing toxicity are also discussed.The authors thank Fundação para a Ciência e a Tecnologia (FCT- MEC, Portugal) for funding—PTDC/QUI-BIO/112929/2009. Diana Gaspar also acknowledges FCT for fellowship SFRH/BPD/ 73500/2010 and A. Salome Veiga for funding within the FCT Investigator Programme (IF/00803/2012

Pharmacological potential of the endogenous dipeptide kyotorphin and selected derivatives

Copyright © 2017 Perazzo, Castanho and Sá Santos. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.The endogenous peptide kyotorphin (KTP) has been extensively studied since it was discovered in 1979. The dipeptide is distributed unevenly over the brain but the majority is concentrated in the cerebral cortex. The putative KTP receptor has not been identified yet. As many other neuropeptides, KTP clearance is mediated by extracellular peptidases and peptide transporters. From the wide spectrum of biological activity of KTP, analgesia was by far the most studied. The mechanism of action is still unclear, but researchers agree that KTP induces Met-enkephalins release. More recently, KTP was proposed as biomarker of Alzheimer disease. Despite all that, KTP limited pharmacological value prompted researchers to develop derivatives more lipophilic and therefore more prone to cross the blood-brain barrier (BBB), and also more resistant to enzymatic degradation. Conjugation of KTP with functional molecules, such as ibuprofen, generated a new class of compounds with additional biological properties. Moreover, the safety profile of these derivatives compared to opioids and their efficacy as neuroprotective agents greatly increases their pharmacological value.Funding was provided by the Portuguese Agency Fundação para a Ciência e a Tecnologia (SFRH/BPD/79542/2011 fellowship to SS and SFRH/BD/52225/2013 fellowship to JP), and by Marie Skłodowska-Curie Research and Innovation Staff Exchange (RISE): call H2020-MSCA-RISE-2014, Grant agreement 644167, 2015-2019.info:eu-repo/semantics/publishedVersio

Produção de biocombustíveis líquidos por pirólise seguida de hidrogenação de óleos alimentares usados

Tese de mestrado integrado, Engenharia da Energia e do Ambiente, Universidade de Lisboa, Faculdade de Ciências, 2014The population growth in recent years and the continuous demand from this population for energy has resulted in increased concerns about the sustainability of the energy production process. On the other hand, the burning of fossil fuels has been causing an alarming increase in emissions of greenhouse gases (GHG) resulting from this energy conversion process, made essential the development of energy production technologies that can replace fossil fuels in a sustainable and economically viable way. Among all developed technologies, one attracted particular interest because it combines the production of "renewable" fuels while eliminating a resultant residue of human activity. This technology is the hydrogenation of oils or fats. In this process, the existing carboxylic chemical bonds present in the triglycerides chain in this raw material are broken down, producing a fuel similar to petroleum, thus, usable in conventional internal combustion engines. This document is based on the study of the yield of production liquid biofuel from a pyrolysis reaction followed by a hydrogenation reaction, analyzing the resulting liquid and gas products. It was tested the effect of temperature, pressure and time in the used frying oil hydrogenation using four different temperatures: 350° C, 380ºC, 400ºC and 430°C; and three pressures: 160 psi, 3 bar and 6 bar, for four different time periods: 15 min, 30 min, 60 min and 90 min. It was found that the highest yield of the liquid fraction was obtained during the hydrogenation at 350°C for 30 minutes, while the gas fraction had a maximum yield at the hydrogenation with 400°C for 90 minutes. Regarding the composition of the products obtained, it was concluded that the compositions of gases collected from different trials are extremely different from the typical natural gas composition, presenting, therefore, a value well below the PCS made by that gas.O crescimento populacional registado nos últimos anos e a contínua demanda desta população por energia resultou num aumento das preocupações relativas à sustentabilidade do processo de produção energético. Por outro lado, a queima de combustíveis fósseis tem vindo a provocar um crescimento alarmante das emissões de gases com efeito de estufa (GEE), resultantes deste processo de conversão de energia, tornando premente o desenvolvimento de tecnologias de produção energética, capazes de substituir os combustíveis fósseis de uma forma sustentada e economicamente viável. De entre todas as tecnologias desenvolvidas, uma tem despertado particular interesse, pois combina a produção de combustíveis “renováveis” enquanto elimina um resíduo resultante da actividade humana. Esta tecnologia é a hidrogenação de óleos ou gorduras. Neste processo, as ligações carboxílicas existentes nas cadeias químicas dos triglicéridos, presentes nesta matéria-prima são quebradas, originando um combustível semelhante ao petróleo, sendo, assim, passível de utilizar nos motores de combustão interna convencionais. O presente documento baseou-se no estudo do rendimento de produção de biocombustíveis líquidos, a partir de uma reacção de pirólise seguida de uma reacção de hidrogenação, sendo analisados os produtos resultantes, líquido e gás. Testou-se o efeito da temperatura, pressão e tempo na hidrogenação do óleo alimentar usado, utilizando quatro temperaturas diferentes: 350ºC, 380ºC, 400ºC e 430ºC, três pressões 160 psi, 3 bar e 6 bar, durante quatro períodos temporais diferentes 15 min, 30 min, 60 min e 90 min. Verificou-se que o maior rendimento de produção da fracção líquida foi obtido no ensaio de hidrogenação a 350ºC durante 30 minutos, enquanto a fracção gasosa teve um rendimento máximo durante a hidrogenação a 400ºC durante 90 minutos. Relativamente à composição dos produtos obtidos, concluiu-se que as composições dos gases recolhidos dos diferentes ensaios são extremamente diferentes da constituição típica do gás natural, apresentando, por isso, um valor de PCS bastante inferior ao apresentado por aquele gás