ATIVIDADE FOTODINÂMICA E CONCEITOS: UM EXPERIMENTO DEMONSTRATIVO

A simple and low cost experiment is proposed to chemistry students associating the Photodynamic Activity involving Chemical and Biochemical concepts. The inclusion of this experiment in undergraduate courses in Chemistry promotes interdisciplinarity and contextualization, combining current and relevant topics to the teaching of program content. The experiment used the Methylene Blue and Erythrosine B as dyes to demonstrate the photodynamic action of these photosensitizers in the inhibition of microbial growth. Both dyes presented satisfactory results against environmental microorganisms. The growth inhibition was caused exclusively by the photochemical processes undergone by the dye/light/oxygen, with LED light exposure

Multivariate analysis of protolytic and tautomeric equilibria of Erythrosine B and its ester derivatives in ionic and non-ionic micelles

Erythrosine B (ERY) is a xanthene dye that has been widely used in recent years as a photoactive drug for Photodynamic Therapy. However, application of ERY and its derivatives as photosensitizer drugs depend not only on their singlet oxygen quantum yield, but also on their hydrophobicity, and photoactive protolytic and tautomeric species. In this work, the objective was to evaluate the acid-base equilibria of ERY and its derivatives: erythrosine methyl ester (ERYMET); erythrosine butyl ester (ERYBUT) and erythrosine decyl ester (ERYDEC), in biomimetic media (micelles of SDS and CTAB) as well as in some drug delivery systems of triblock copolymer Poloxamer (P-123 and F-127). All protolytic chemical equilibria were studied by employing chemometric multivariate analysis based on the Imbrie's Q-Mode Factor Analysis and k-Matrix methods. Tautomeric equilibria were evaluated taking into account of possible chemical structures and electronic spectroscopic approximations. Results from ester derivatives presenting only one protolytic equilibrium (at the phenolate group) and two possible tautomers, allow us to determine that protolytic equilibria follow the sequence pKaCOOH < pKaOH in SDS media for ERY by structure comparison. On the other hand, CTAB and polaxamers inverted the acidity of ERY protolytic groups (pKaOH < pKaCOOH) due to changes in the tautomeric equilibrium due to a lactone formation for the dyes neutral protolytic species inside the micelles. Chemometric approaches provided detailed analyses of protolytic/tautomeric equilibria of ERY. Through this, we achieved a deeper understanding of how ERY and its derivatives are affected by microenvironments in biomimetic and drug delivery systems.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP: 2019/01604-

Chemical equilibria of Eosin Y and its synthetic ester derivatives in non-ionic and ionic micellar environments

Eosin (EOS) and its synthetic ester derivatives have adequate properties to be employed as histological markers for and as drugs for photodynamic therapy. However, they present a very complex protolytic and tautomeric equilibrium that reflects on their photophysical properties. Hence their biomedical applications are strongly affected by the medium's pH, charge and hydrophobicity. In this study, we evaluated the effects of two neutral (Pluronic® F-127 and P-123) and two ionic (anionic SDS and cationic CTAB) surfactant micelles as a simple membrane model on the protolytic/tautomeric equilibrium of EOS and its ester derivative dyes. Multivariate analysis based on Q-Imbrie's factor and the K-matrix method on the electronic absorption spectroscopy data in different pH conditions allowed for the understanding of the complex protolytic/tautomeric equilibrium, and the influence of medium microenvironment on the EOS dyes at each pH. Our results demonstrated that, when close to physiological pH (~7.4), and electrostatic attraction towards cationic surfaces favor dyes locating close to the micelle's (biomembrane model) interface, where their biomedical applications are favored. Therefore, the analysis in different environments shows that the interactions of EOS and its derivatives with biomembranes can be modulated based on the hydrophobicity of the xanthene derivative and the cell membrane charge.Não recebi financiament

PHOTODYNAMIC ACTIVITY AND CONCEPTS: A DEMONSTRATIVE EXPERIMENT

<p></p><p>A simple and low cost experiment is proposed to chemistry students associating the Photodynamic Activity involving Chemical and Biochemical concepts. The inclusion of this experiment in undergraduate courses in Chemistry promotes interdisciplinarity and contextualization, combining current and relevant topics to the teaching of program content. The experiment used the Methylene Blue and Erythrosine B as dyes to demonstrate the photodynamic action of these photosensitizers in the inhibition of microbial growth. Both dyes presented satisfactory results against environmental microorganisms. The growth inhibition was caused exclusively by the photochemical processes undergone by the dye/light/oxygen, with LED light exposure.</p><p></p

A quimiometria nos cursos de graduação em química: proposta do uso da análise multivariada na determinação de pk&#170;

An experiment was proposed applying the Chemometric approach of Multivariate Analysis for inclusion in undergraduate Chemistry courses to promote and expand the use of this analytical-statistical tool. The experiment entails the determination of the acid dissociation constant of dyes via UV-Vis electronic spectrophotometry. The dyes used show from simple equilibrium to very complex systems involving up to four protolytic species with high spectral overlap. The Chemometric methodology was more efficient than univariate methods. For use in classes, it is up to the teacher to decide which systems should be utilized given the time constraints and laboratory conditions

Clinical utility of polymerase chain reaction-based detection of Leishmania in the diagnosis of American cutaneous leishmaniasis.

Submitted by Ana Maria Fiscina Sampaio ([email protected]) on 2014-07-09T13:53:09Z No. of bitstreams: 1 Oliveira CI Clinical utility....pdf: 108313 bytes, checksum: a0806eadf613e91fe4ca5607f9f9f6c3 (MD5)Made available in DSpace on 2014-07-09T13:53:09Z (GMT). No. of bitstreams: 1 Oliveira CI Clinical utility....pdf: 108313 bytes, checksum: a0806eadf613e91fe4ca5607f9f9f6c3 (MD5) Previous issue date: 2003Fundação Oswaldo Cruz. Centro de Pesquisa Gonçalo Moniz. Salvador, BA, BrasilFundação Oswaldo Cruz. Centro de Pesquisa Gonçalo Moniz. Salvador, BA, BrasilFundação Oswaldo Cruz. Centro de Pesquisa Gonçalo Moniz. Salvador, BA, Brasil / Universidade Federal da Bahia. Faculdade de Medicina da Bahia. Salvador, BA, BrasilFundação Oswaldo Cruz. Centro de Pesquisa Gonçalo Moniz. Salvador, BA, Brasil / Universidade Federal da Bahia. Faculdade de Medicina da Bahia. Salvador, BA, BrasilFundação Oswaldo Cruz. Centro de Pesquisa Gonçalo Moniz. Salvador, BA, BrasilFundação Oswaldo Cruz. Centro de Pesquisa Gonçalo Moniz. Salvador, BA, Brasil / Universidade Federal da Bahia. Faculdade de Medicina da Bahia. Salvador, BA, BrasilCentro de Referência para Doenças Endêmicas Pirajá da Silva. Jequié, BA, BrasilFundação Oswaldo Cruz. Centro de Pesquisa Gonçalo Moniz. Salvador, BA, BrasilFundação Oswaldo Cruz. Centro de Pesquisa Gonçalo Moniz. Salvador, BA, Brasil / Universidade Federal da Bahia. Faculdade de Medicina da Bahia. Salvador, BA, BrasilWe evaluated the use of polymerase chain reaction (PCR) for diagnosis of American cutaneous leishmaniasis (ACL) in an area in Bahia, Brazil, where Leishmania braziliensis is endemic. Leishmania DNA was detected in 50 cases, yielding a positivity rate of 100%, which was higher than the rates for all of the other diagnostic methods studied--namely, the Montenegro skin test, anti-Leishmania serological testing, and microscopic examination of lesion biopsy specimens. These findings have led us to propose guidelines for the diagnosis of ACL that use PCR as the principal means of parasitological confirmation of case

Clinical and cytogenetic features of a Brazilian sample of patients with phenotype of oculo-auriculo-vertebral spectrum: a cross-sectional study

CONTEXT AND OBJECTIVE: Oculo-auriculo-vertebral spectrum (OAVS) is considered to be a defect of embryogenesis involving structures originating from the first branchial arches. Our objective was to describe the clinical and cytogenetic findings from a sample of patients with the phenotype of OAVS.DESIGN AND SETTING: Cross-sectional study in a referral hospital in southern Brazil.METHODS: The sample consisted of 23 patients who presented clinical findings in at least two of these four areas: orocraniofacial, ocular, auricular and vertebral. The patients underwent a clinical protocol and cytogenetic evaluation through high-resolution karyotyping, fluorescence in situ hybridization for 5p and 22q11 microdeletions and investigation of chromosomal instability for Fanconi anemia.RESULTS: Cytogenetic abnormalities were observed in three cases (13%) and consisted of: 47,XX,+mar; mos 47,XX,+mar/46,XX; and 46,XX,t(6;10)(q13; q24). We observed cases of OAVS with histories of gestational exposition to fluoxetine, retinoic acid and crack. One of our patients was a discordant monozygotic twin who had shown asymmetrical growth restriction during pregnancy. Our patients with OAVS were characterized by a broad clinical spectrum and some presented atypical findings such as lower-limb reduction defect and a tumor in the right arm, suggestive of hemangioma/lymphangioma.CONCLUSIONS: We found a wide range of clinical characteristics among the patients with OAVS. Different chromosomal abnormalities and gestational expositions were also observed. Thus, our findings highlight the heterogeneity of the etiology of OAVS and the importance of these factors in the clinical and cytogenetic evaluation of these patients