Famous Brazilian educational and social theorist Paulo Freire presents his ideas on the importance of community solidarity in moving toward social justice in schools and society. In a set of talks ...and interviews shortly before his death, Freire addresses issues not often highlighted in his work, such as globalization, post-modern fatalism, and the qualities of educators for the 21st century. His illuminating comments are supplemented with commentaries by other well-known scholars, such as Ana Maria Araujo Freire, Walter de Oliveira, Norman Denzin, Henry Giroux, and Donaldo Macedo.
Natural phenolic compounds are abundant in the vegetable kingdom, occurring mainly as secondary metabolites in a wide variety of chemical structures. Around 10,000 different plant phenolic ...derivatives have been isolated and identified. This review provides an exhaustive overview concerning the electron transfer reactions in natural polyphenols, from the point of view of their in vitro antioxidant and/or pro‐oxidant mode of action, as well as their identification in highly complex matrixes, for example, fruits, vegetables, wine, food supplements, relevant for food quality control, nutrition, and health research. The accurate assessment of polyphenols’ redox behavior is essential, and the application of the electrochemical methods in routine quality control of natural products and foods, where the polyphenols antioxidant activity needs to be quantified in vitro, is of the utmost importance. The phenol moiety oxidation pathways and the effect of substituents and experimental conditions on their electrochemical behavior will be reviewed. The fundamental principles concerning the redox behavior of natural polyphenols, specifically flavonoids and other benzopyran derivatives, phenolic acids and ester derivatives, quinones, lignins, tannins, lignans, essential oils, stilbenes, curcuminoids, and chalcones, will be described. The final sections will focus on the electroanalysis of phenolic antioxidants in natural products and the electroanalytical evaluation of in vitro total antioxidant capacity.
Applications of a DNA-electrochemical biosensor Diculescu, Victor Constantin; Chiorcea-Paquim, Ana-Maria; Oliveira-Brett, Ana Maria
TrAC, Trends in analytical chemistry (Regular ed.),
20/May , Letnik:
79
Journal Article
Recenzirano
•Design of DNA-electrochemical biosensors that use DNA direct electrochemistry.•AFM and voltammetric characterization of new immobilisation procedures described.•Self-assembled nanostructures of DNA, ...G-quadruplex, and i-motif presented.•Application for label-free detection of DNA interactions and damage.•Interaction with proteins, drugs, metals, pollutants, radicals, and radiation, revised.
As carrier of genetic information, DNA is one of the most important intracellular targets that undergo modification and damage upon interaction with endogenous and exogenous factors. DNA is an excellent biomaterial for the construction of new devices, in nanotechnology and biosensor technology, for evaluation of DNA interaction with a broad range of chemical compounds and biomolecules, essential from a biological and a medical point of view.
This review discusses recent advances on the design and applications of DNA-electrochemical biosensors that use DNA direct electrochemistry as a detection platform. AFM and voltammetric characterization of new bottom up immobilisation procedures of self-assembled nanostructures based on DNA single- and double-stranded, G-quadruplex, and i-motif configurations are presented, relevant for the development of new DNA-electrochemical biosensor devices. The applications of DNA-electrochemical biosensors, for the label-free detection of interactions with proteins, pharmaceutical compounds, metal ions and metal complexes, pollutants, free radicals, and electromagnetic radiation, were revisited.
Deoxyribonucleic acid (DNA) electrochemical biosensors are devices that incorporate immobilized DNA as a molecular recognition element on the electrode surface, and enable probing in situ the ...oxidative DNA damage. A wide range of DNA electrochemical biosensor analytical and biotechnological applications in pharmacology are foreseen, due to their ability to determine in situ and in real-time the DNA interaction mechanisms with pharmaceutical drugs, as well as with their degradation products, redox reaction products, and metabolites, and due to their capacity to achieve quantitative electroanalytical evaluation of the drugs, with high sensitivity, short time of analysis, and low cost. This review presents the design and applications of label-free DNA electrochemical biosensors that use DNA direct electrochemical oxidation to detect oxidative DNA damage. The DNA electrochemical biosensor development, from the viewpoint of electrochemical and atomic force microscopy (AFM) characterization, and the bottom-up immobilization of DNA nanostructures at the electrode surface, are described. Applications of DNA electrochemical biosensors that enable the label-free detection of DNA interactions with pharmaceutical compounds, such as acridine derivatives, alkaloids, alkylating agents, alkylphosphocholines, antibiotics, antimetabolites, kinase inhibitors, immunomodulatory agents, metal complexes, nucleoside analogs, and phenolic compounds, which can be used in drug analysis and drug discovery, and may lead to future screening systems, are reviewed.
Natural dietary agents have attracted considerable attention due to their role in promoting health and reducing the risk of diseases including cancer. Ginger, one of the most ancient known spices, ...contains bioactive compounds with several health benefits. 6‐Gingerol constitutes the most pharmacologically active among such compounds. The aim of the present work was to review the literature pertaining to the use of ginger extract and 6‐gingerol against tumorigenic and oxidative and inflammatory processes associated with cancer, along with the underlying mechanisms of action involved in signaling pathways. This will shed some light on the protective or therapeutic role of ginger derivatives in oxidative and inflammatory regulations during metabolic disturbance and on the antiproliferative and anticancer properties. Data collected from experimental (in vitro or in vivo) and clinical studies discussed in this review indicate that ginger extract and 6‐gingerol exert their action through important mediators and pathways of cell signaling, including Bax/Bcl2, p38/MAPK, Nrf2, p65/NF‐κB, TNF‐α, ERK1/2, SAPK/JNK, ROS/NF‐κB/COX‐2, caspases‐3, ‐9, and p53. This suggests that ginger derivatives, in the form of an extract or isolated compounds, exhibit relevant antiproliferative, antitumor, invasive, and anti‐inflammatory activities.
Oxidative DNA damage plays an important role in the pathogenesis of various diseases. Among oxidative DNA lesions, 8-oxoguanine (8-oxoG) and its corresponding nucleotide 8-oxo-2′-deoxyguanosine ...(8-oxodG), the guanine and deoxyguanosine oxidation products, have gained much attention, being considered biomarkers for oxidative DNA damage. Both 8-oxoG and 8-oxodG are used to predict overall body oxidative stress levels, to estimate the risk, to detect, and to make prognosis related to treatment of cancer, degenerative, and other age-related diseases. The need for rapid, easy, and low-cost detection and quantification of 8-oxoG and 8-oxodG biomarkers of oxidative DNA damage in complex samples, urine, blood, and tissue, caused an increasing interest on electrochemical sensors based on modified electrodes, due to their high sensitivity and selectivity, low-cost, and easy miniaturization and automation. This review aims to provide a comprehensive and exhaustive overview of the fundamental principles concerning the electrochemical determination of the biomarkers 8-oxoG and 8-oxodG using nanostructured materials (NsM), such as carbon nanotubes, carbon nanofibers, graphene-related materials, gold nanomaterials, metal nanoparticles, polymers, nanocomposites, dendrimers, antibodies and aptamers, and modified electrochemical sensors.
Graphical abstract
Alkylating agents were among the first anticancer drugs to be discovered and continue to be the most commonly used in chemotherapy. They are electrophiles that react with the ring nitrogen and ...extracyclic oxygen atoms of DNA bases, forming covalent adducts that further lead to cross-linking of DNA strands, abnormal base pairing or DNA strand breaks. The investigation and quantitative analysis of alkylating agents in biological samples are essential for monitoring the therapy progression and efficiency, understanding their pharmacokinetics and develop new more effective and specific chemotherapeutical drugs. Among biotechnological methods, electrochemical techniques are particularly important in pharmaceutical medicine, owing to their rapid detection, great sensitivity, robustness, exceptional detection limits, ability to be used with small analyte volumes in turbid biofluids, and easy adaptability to miniaturization and point-of-care (POC) testing. This article provides first an exhaustive review concerning the electrochemical methods of characterization and quantification of different classes of chemotherapeutic alkylating agents (triazenes and hydrazines, nitrosoureas, nitrogen mustards, oxazaphosphorines, alkyl alkane sulfonates and ethylene imines) in standard samples, pharmaceutical formulations and biological matrixes. The second part of the article focuses on the recent electrochemical methodologies and DNA-electrochemical biosensors developed to study the interaction of alkylating agents with DNA. These studies are relevant for obtaining real-time details about the alkylating agents’ mechanism of action and for assessing the oxidative DNA damage they cause, important for the development of improved antineoplastic drugs.
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•Alkylating agents were among the first anticancer drugs used in chemotherapy.•They react with DNA bases, forming covalent adducts.•Electrochemical methods to study chemotherapeutic alkylating agents.•DNA-electrochemical biosensors developed to study DNA-alkylating agents’ interaction.
Summary Background Zika virus is an arthropod-borne virus that is a member of the family Flaviviridae transmitted mainly by mosquitoes of the genus Aedes . Although usually asymptomatic, infection ...can result in a mild and self-limiting illness characterised by fever, rash, arthralgia, and conjunctivitis. An increase in the number of children born with microcephaly was noted in 2015 in regions of Brazil with high transmission of Zika virus. More recently, evidence has been accumulating supporting a link between Zika virus and microcephaly. Here, we describe findings from three fatal cases and two spontaneous abortions associated with Zika virus infection. Methods In this case series, formalin-fixed paraffin-embedded tissue samples from five cases, including two newborn babies with microcephaly and severe arthrogryposis who died shortly after birth, one 2-month-old baby, and two placentas from spontaneous abortions, from Brazil were submitted to the Infectious Diseases Pathology Branch at the US Centers for Disease Control and Prevention (Atlanta, GA, USA) between December, 2015, and March, 2016. Specimens were assessed by histopathological examination, immunohistochemical assays using a mouse anti-Zika virus antibody, and RT-PCR assays targeting the NS5 and envelope genes. Amplicons of RT-PCR positive cases were sequenced for characterisation of strains. Findings Viral antigens were localised to glial cells and neurons and associated with microcalcifications in all three fatal cases with microcephaly. Antigens were also seen in chorionic villi of one of the first trimester placentas. Tissues from all five cases were positive for Zika virus RNA by RT-PCR, and sequence analyses showed highest identities with Zika virus strains isolated from Brazil during 2015. Interpretation These findings provide strong evidence of a link between Zika virus infection and different congenital central nervous system malformations, including microcephaly as well as arthrogryposis and spontaneous abortions. Funding None.
Bioaromas – Perspectives for sustainable development Felipe, Lorena de Oliveira; Oliveira, Ana Maria de; Bicas, Juliano Lemos
Trends in Food Science & Technology,
April 2017, 2017-04-00, 20170401, Letnik:
62
Journal Article
Recenzirano
Aroma compounds can be produced using three main methods: chemical synthesis, extraction from nature, and biotechnological process (bioaromas). In the latter method, when compared with chemical ...synthesis and direct extraction from nature, the (bio)aroma compounds obtained present numerous advantages, in such a way that this approach meets two important demands of modern society: the first one refers to products obtained by biotechnological processes, which can be considered as natural, and the second one is related to the concept of sustainable development, since such production processes are aligned with the best practices in environmental preservation.
In this review we demonstrate that the technological development of the production of aroma compounds using microorganisms is effectively promising as a process that allows the inextricably approach of the three pillars of sustainability: environment, economics, and social aspects.
This review shows that bioaroma production consists of renewable processes that employ mild conditions of operation, do not generate toxic waste, uses biodiversity rationally, and may also avail agro-industrial residues or by-products in a special way. Moreover, biological (e.g., antioxidant, anticancer, anti-inflammatory) activities attributed to some terpene biotransformation products are increasingly being reported, indicating that their applications may transcend food industry.
•Bioaromas are natural aroma compounds biotechnologically produced.•Bioaroma production is aligned with the three pillars of sustainability.•Microbial aroma production is an environmentally friendly approach.•There is an increasing market for natural aromas and bioaroma has competitive prices.•Increasing reports show bioactivities of terpene biotransformation products.
► Electrochemical behaviour of phenol, catechol, hydroquinone, resorcinol, dopamine. ► Electrochemical behaviour of
para-substituted phenolic compounds, 4-ethylphenol, tyrosine, and tyramine. ► ...Electrochemical mechanistic behaviour of
para-substituted phenols.
The electrochemical behaviour of phenol, catechol, hydroquinone, resorcinol, dopamine, and
para-substituted phenolic compounds, 4-ethylphenol, tyrosine, and tyramine, was studied over a wide pH range using a glassy carbon electrode. The oxidation of phenol is pH dependent and irreversible, occurring in one step, and followed by hydrolyse in
ortho- and
para-positions, leading to two oxidation products, catechol and hydroquinone. The oxidation of phenol oxidation products,
ortho-phenol and
para-phenol, is reversible and pH dependent. The oxidation potential of
para-substituted phenols varies slightly due to their substituent group in position C4, and occurs in one oxidation step corresponding to the oxidation of phenol. The oxidation products of this group of
para-substituted phenols are reversibly oxidised and adsorb on the electrode surface.
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