Síntese de novos derivados tetrapirrólicos

Mestrado em Química de Produtos NaturaisA presente dissertação contempla a síntese de díades porfirina-ftalocianina e descreve os resultados obtidos em estudos de funcionalização de 5,10,15,20- tetra-arilporfirinas, via grupos amino e nitro. Este trabalho encontra-se dividido em quatro partes. Na primeira parte descrevem-se as características gerais de porfirinas e ftalocianinas, bem como algumas metodologias sintéticas utilizadas na sua preparação e potenciais aplicações. A segunda parte desta dissertação descreve a síntese de díades porfirinaftalocianina recorrendo à condensação cruzada entre a 5,10,15,20- tetrafenilporfirina substituída na posição beta-pirrólica por um grupo ftalonitrilo e a unidade de ftalonitrilo e ftalonitrilos substituídos. Pela primeira vez, os dois crómoforos estão directamente ligados, sem qualquer espaçador, através da posição beta-pirrólica da 5,10,15,20-tetrafenilporfirina. A porfirina-ftalonitrilo necessária para a síntese das díades foi preparada através da reacção de adição de fumaronitrilo à 5,10,15,20-tetrafenilporfirina funcionalizada com o grupo 1,3-butadienilo, seguida de oxidação do aducto resultante. Os estudos fotofísicos das díades acima referidas permitiram verificar a ocorrência eficiente de transferência de energia da unidade porfirínica para a ftalocianina, capacidade essa que permitirá a estes sistemas serem usados para modelar a função antena do processo fotossintético. Na terceira parte deste trabalho descreve-se a funcionalização de 5,10,15,20- tetra-arilporfirinas com aminas aromáticas usando duas rotas sintéticas diferentes. A reacção de 2-nitro-5,10,15,20-tetra-arilporfirinas com aminas aromáticas originou novos derivados do tipo 2-arilaminoporfirinas. Verificou-se que esta metodologia é apenas aplicável à anilina e anilinas substituídas com grupos dadores de electrões. Nesta rota sintética também se obtiveram derivados porfirínicos de anéis fundidos. A reacção entre o 2-amino-5,10,15,20-tetrafenilporfirinato Ni(II) e brometos de arilo na presença de paládio, reacção de arilação de Buchwald-Hartwig, permitiu, após reacção de descomplexação, a obtenção de novos derivados do tipo 2-arilaminoporfirinas com grupos substituintes dadores e aceitadores de electrões. Na última parte descrevem-se, pormenorizadamente, todas as experiências efectuadas e as caracterizações espectroscópicas, nomeadamente de espectroscopia de ressonância magnética nuclear (RMN), espectrometria de massa em FAB+ e espectroscopia de UV-vis, dos compostos sintetizados. Nalguns casos recorreu-se ainda a técnicas de RMN bidimensionais como COSY, HSQC, HMBC e NOESY. ABSTRACT: The work presented in this dissertation describes the synthesis of porphyrinphthalocyanine dyads and functionalization, via nitro and amino groups, of 5,10,15,20-tetraarylporphyrins with aromatic amines. In the first part the general properties of porphyrins and phthalocyanines are described and also some synthetic methodologies used in their preparation and some potential applications. The second part of this dissertation describes, after a brief reference to biomimetic models for natural photosynthesis processes, the synthesis of porphyrin-phthalocyanine dyads by crossover condensation of a porphyrinphthalonitrile derivative with different non-porphyrinic phthalonitriles. For the first time, these two chromophoric units are directly linked, without any spacer, through the beta-pyrrolic position of 5,10,15,20-tetraphenylporphyrin. The porphyrin-phthalonitrile was obtained by Diels-Alder reaction between the 1,3- butadienyl porphyrin (obtained by the thermal extrusion of SO2 from a sulfolene derivate) with fumaronitrile, followed by the oxidation of the resulting adduct. The porphyrin-phthalocyanine dyads photophysical studies demonstrated an efficient energy transfer between chromophores, which indicates that these compounds may be used as antennae on biomimetic model systems of natural photosynthesis. In the third part of this work it is described the functionalization of 5,10,15,20- tetraarylporphyrins with aromatic amines using two different synthetic routes. The reaction of 2-nitro-5,10,15,20-tetraarylporphyrins with aromatic amines provides new 2-arylaminoporphyrins. This synthetic methodology is only applied to aniline and anilines substituted with electron donating groups. This reaction also provides the formation of new porphyrin derivatives bearing fused rings. The reaction of Ni(II) complex of 2-amino-5,10,15,20-tetraphenylporphyrin with aryl bromides, in the presence of palladium, Buchwald-Hartwig amination, leads, after demetallation, to 2-arylaminoporphyrins bearing electron donating and electron withdrawing groups. In the last part there is a description of all experimental methodologies used on this work. All of the synthesized compounds were characterized by nuclear magnetic resonance, mass spectrometry and UV-vis spectroscopy. In some cases, several 2D-NMR techniques were used, namely, COSY, HSQC, HMBC and NOESY

Síntese de derivados oligoméricos de porfirinas e ftalocianinas

Doutoramento em QuímicaA presente dissertação contempla estudos de funcionalização de 5,10,15,20- tetrafenilporfirina via grupos nitro e amino e a preparação de sistemas porfirina-ftalocianina. Este trabalho encontra-se dividido em quatro partes. Na primeira parte descrevem-se as características gerais de porfirinas e ftalocianinas bem como algumas metodologias de síntese utilizadas na sua preparação e suas potenciais aplicações. Na segunda parte desta dissertação descreve-se a funcionalização de 5,10,15,20-tetrafenilporfirina com arilaminas recorrendo a duas rotas sintéticas diferentes. A reacção de 2-nitro-5,10,15,20-tetrafenilporfirina com anilina ou aminas aromáticas substituídas com grupos dadores de electrões permitiu, através do ataque do nucleófilo ao carbono beta-pirrólico onde está ligado o grupo nitro, ataque ipso, a obtenção de derivados do tipo 2-arilaminoporfirinas e derivados porfirínicos de anéis fundidos, sendo estes últimos resultantes da ciclização oxidativa de 2-arilaminoporfirinas. A reacção entre (2-amino- 5,10,15,20-tetrafenilporfirinato)níquel(II) e brometos de arilo na presença de paládio, reacção de aminação de Buchwald-Hartwig, permitiu, após descomplexação, a preparação de novos derivados do tipo 2- arilaminoporfirinas com grupos substituintes dadores e aceitadores de electrões. Um dos derivados porfirínicos de anéis fundidos foi submetido a reacção de complexação com diferentes iões metálicos e foram estudadas as respectivas propriedades fotoquímicas e electroquímicas. Esses estudos revelaram que estes compostos são bons geradores de oxigénio singuleto e que sofrem processos de oxidação-redução electroquimicamente reversíveis. Esta metodologia foi estendida ainda a brometos de hetarilo (derivados de piridina e tiofeno). Recorrendo ao acoplamento, em condições de Buchwald-Hartwig, de complexos metálicos da 5,10,15,20-tetrafenilporfirina, funcionalizados com grupos amino e bromo, preparam-se dímeros porfirina-amino-porfirina, cujos espectros electrónicos revelam a existência de uma boa “comunicação electrónica” entre as duas subunidades. A terceira parte descreve a síntese de sistemas porfirina-ftalocianina. Recorrendo à condensação estatística entre a 5,10,15,20-tetrafenilporfirina substituída com um grupo ftalonitrilo na posição beta-pirrólica com ftalonitrilo ou ftalonitrilo substituído foram obtidas díades porfirina-ftalocianina onde as duas subunidades se encontram directamente ligadas ou fundidas. Os porfirinilftalonitrilos necessários para a síntese das diferentes díades foram preparados através da reacção de adição do fumaronitrilo à 5,10,15,20- tetrafenilporfirina funcionalizada com o grupo 1,3-butadienilo ou vinilo, seguida de oxidação do aducto resultante. O acoplamento catalisado por paládio entre (2-bromo-5,10,15,20- tetrafenilporfirinato)zinco(II) e [9(10),16(17),23(24)-tri-terc-butil-2- etinilftalocianinato]zinco(II) permitiu a síntese de uma díade porfirinaftalocianina com as duas unidades ligadas por um grupo etinilo. Uma pentíade porfirina-ftalocianina foi obtida através da ciclotetramerização de um dos porfirinilftalonitrilos. A comparação dos espectros electrónicos das diferentes classes de sistemas revela que as correspondentes propriedades electrónicas são altamente afectadas pela distância entre as subunidades e também pelo número de cromóforos presentes no sistema. Os estudos fotofísicos de alguns dos novos compostos acima referidos permitiram verificar a ocorrência eficiente de transferência de energia da subunidade porfirínica para a da ftalocianina, capacidade essa que permitirá a estes sistemas serem usados para modelar o processo fotossintético. Na última parte descrevem-se, pormenorizadamente, todas as experiências efectuadas e as caracterizações espectroscópicas, nomeadamente de espectroscopia de ressonância magnética nuclear (RMN), espectrometria de massa e espectrofotometria de UV-vis, dos compostos sintetizados. Nalguns casos recorreu-se ainda a técnicas de RMN bidimensionais como COSY, HSQC, HMBC, NOESY e ROESY.In this dissertation are described the functionalization of 5,10,15,20- tetraphenylporphyrin via nitro and amino groups and the preparation of novel porphyrin-phthalocyanine derivatives. In the first part, are discussed the general properties of porphyrins and phthalocyanines, synthetic methodologies used for their preparation, and some important potential applications. In the second part, the functionalization of 5,10,15,20-tetraphenylporphyrin with arylamines using two different routes is described. The reaction of 2-nitro- 5,10,15,20-tetraphenylporphyrin with aniline and anilines substituted with electron donating groups allows, via ipso attack, the obtention of new 2- arylaminoporphyrins and porphyrin derivatives bearing fused rings. These last compounds resulted from the oxidative cyclization of 2-arylaminoporphyrins. The reaction of (2-amino-5,10,15,20-tetraphenylporphyrinato)nickel(II) and aryl bromides in presence of palladium complexes under Buchwald conditions led, after demetalation, to 2-arylaminoporphyrins bearing electron donating and withdrawing groups. From one of these new fused derivatives several metal complexes were prepared and their photochemistry and electrochemistry investigated. The studies revealed that these molecules were good singlet oxygen generators and gave well-defined one-electron reversible oxidation steps as well as well-defined one-electron reversible reduction steps. This methodology was extended to hetaryl bromides, such as 3- bromothiophene and 3-bromopyridine, and porphyrin-porphyrin dimers containing different metals. These dimers exhibited electronic spectra showing features that suggested a good electronic communication between the two subunits. In the third part are described the syntheses of porphyrin-phthalocyanine systems. The statistical crossover condensation of porphyrinylphthalonitrile with phthalonitrile or substituted phthalonitriles allowed the preparation of porphyrinphthalocyanine dyads in which the two subunits are directly linked or fused. The porphyrinylphthalonitrile precursors were obtained by Diels-Alder reaction between fumaronitrile and porphyrins containing a 1,3-butadienyl or a vinyl group, followed by the oxidation of the resulting adduct. The palladium-catalyzed coupling of (2-bromo-5,10,15,20- tetraphenylporphyrinato)zinc(II) with [9(10),16(17),23(24)-tri-tert-butyl-2- ethynylphthalocyaninato]zinc(II) gave a porphyrin-phthalocyanine dyad having the two components connected through an ethynyl group. A porphyrin-phthalocyanine pentad was obtained via cyclotetramerization of a porphyrinylphthalonitrile. The different classes of compounds revealed that the corresponding electronic properties were highly affected by the distance and orientation between the subunits and also by the chromophore number. The photophysical studies of some systems demonstrated an efficient energy transfer from the porphyrin unit to the phthalocyanine, and this indicated that these compounds might be used to mimic the photosynthetic process. In the last part are described the experimental procedures used to obtain all new compounds. All new molecules were characterized by nuclear magnetic resonance, mass spectrometry and UV-vis spectrophotometry. In some cases, several 2D-NMR techniques were used, namely, COSY, HSQC, HMBC, NOESY and ROESY

Complete blood count parameters as biomarkers of retinopathy of prematurity: a Portuguese multicenter study

© The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Purpose: To evaluate complete blood count (CBC) parameters in the first week of life as predictive biomarkers for the development of retinopathy of prematurity (ROP). Methods: Multicenter, prospective, observational study of a cohort of preterm infants born with gestational age (GA) < 32 weeks or birth weight < 1500 g in eight Portuguese neonatal intensive care units. All demographic, clinical, and laboratory data from the first week of life were collected. Univariate logistic regression was used to assess risk factors for ROP and then multivariate regression was performed. Results: A total of 455 infants were included in the study. The median GA was 29.6 weeks, and the median birth weight was 1295 g. One hundred and seventy-two infants (37.8%) developed ROP. Median values of erythrocytes (p < 0.001), hemoglobin (p < 0.001), hematocrit (p < 0.001), mean corpuscular hemoglobin concentration (p < 0.001), lymphocytes (p = 0.035), and platelets (p = 0.003) of the group of infants diagnosed with ROP any stage were lower than those without ROP. Mean corpuscular volume (MCV) (p = 0.044), red blood cell distribution width (RDW) (p < 0.001), erythroblasts (p < 0.001), neutrophils (p = 0.030), neutrophils-lymphocytes ratio (p = 0.028), and basophils (p = 0.003) were higher in the ROP group. Higher values of MCV, erythroblasts, and basophils remained significantly associated with ROP after multivariate regression. Conclusion: In our cohort, the increase in erythroblasts, MCV, and basophils in the first week of life was significantly and independently associated with the development of ROP. These CBC parameters may be early predictive biomarkers for ROP.Open access funding provided by FCT|FCCN (b-on). This work was supported by the Laboratório de Genética and the Instituto de Saúde Ambiental (ISAMB) of the Faculdade de Medicina of Universidade de Lisboa and the Instituto de Investigação Científica Bento da Rocha Cabral. The writing of the manuscript was also supported by funds from Fundação para a Ciência e a Tecnologia to ISAMB (ref. UIDB/04295/2020 and UIDP/04295/2020). This work was also part of a doctoral project funding by the company CUF with a PhD grant in Medicine awarded in 2021 and by the Portuguese Society of Ophthalmology with a PhD grant awarded in 2019.info:eu-repo/semantics/publishedVersio

A small TAT-TrkB peptide prevents BDNF receptor cleavage and restores synaptic physiology in Alzheimer's disease

Publisher Copyright: Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.In Alzheimer's disease (AD), amyloid β (Aβ)-triggered cleavage of TrkB-FL impairs brain-derived neurotrophic factor (BDNF) signaling, thereby compromising neuronal survival, differentiation, and synaptic transmission and plasticity. Using cerebrospinal fluid and postmortem human brain samples, we show that TrkB-FL cleavage occurs from the early stages of the disease and increases as a function of pathology severity. To explore the therapeutic potential of this disease mechanism, we designed small TAT-fused peptides and screened their ability to prevent TrkB-FL receptor cleavage. Among these, a TAT-TrkB peptide with a lysine-lysine linker prevented TrkB-FL cleavage both in vitro and in vivo and rescued synaptic deficits induced by oligomeric Aβ in hippocampal slices. Furthermore, this TAT-TrkB peptide improved the cognitive performance, ameliorated synaptic plasticity deficits and prevented Tau pathology progression in vivo in the 5XFAD mouse model of AD. No evidence of liver or kidney toxicity was found. We provide proof-of-concept evidence for the efficacy and safety of this therapeutic strategy and anticipate that this TAT-TrkB peptide has the potential to be a disease-modifying drug that can prevent and/or reverse cognitive deficits in patients with AD.publishersversionpublishe

Syntheses and Electrochemical and EPR Studies of Porphyrins Functionalized with Bulky Aromatic Amine Donors

A series of nickel(II) porphyrins bearing one or two bulky nitrogen donors at the meso positions were prepared by using Ullmann methodology or more classical Buchwald–Hartwig amination reactions to create the new C-N bonds. For several new compounds, single crystals were obtained, and the X-ray structures were solved. The electrochemical data of these compounds are reported. For a few representative examples, spectroelectrochemical measurements were used to clarify the electron exchange process. In addition, a detailed electron paramagnetic resonance (EPR) study was performed to estimate the extent of delocalization of the generated radical cations. In particular, electron nuclear double resonance spectroscopy (ENDOR) was used to determine the coupling constants. DFT calculations were conducted to corroborate the EPR spectroscopic data

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved