Raman, IR, UV–vis and EPR characterization of two copper dioxolene complexes derived from L-dopa and dopamine

Barreto, Wagner José; Barreto, Sônia Regina Giancoli; Ando, Rômulo Augusto; Santos, Paulo S.; DiMauro, Eduardo; Jorge, Thiago Perez

doi:10.1016/j.saa.2008.04.014

Cited by 46 publications

(23 citation statements)

References 20 publications

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“…Complex 1 crystallizes in the monoclinic space group C2/c, and the asymmetric unit, which has one Co ion coordinated with one dbbq and one pyrimidine (that is, half of the bpym ligand) group, is the same at two temperatures, which leads to averaged bond lengths. [15][16][17] The C-O stretching modes, such as the intense absorption bands at ca. The C-O bond lengths are 1.286(6) and 1.284(6) Å.…”

Section: Resultsmentioning

confidence: 99%

A Switchable Complex Ligand Exhibiting Photoinduced Valence Tautomerism

Dai

Kanegawa

et al. 2013

Eur J Inorg Chem

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The crystal of a valence tautomeric cobalt complex, [Co(dbbq) 2 (bpym)](1) (dbbq = 3,6-di-tert-butyl-1,2-benzoquinone and bpym = 2,2Ј-bipyrimidine), have been obtained by reaction between Co 2 (CO) 8 and dbbq in the presence of the ligand bpym in a mixed solvent under an N 2 atmosphere. The magnetic behavior of complex 1 clearly indicates that electron transfer from the catecholate ligand to the Co III cen-

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Section: Resultsmentioning

confidence: 99%

A Switchable Complex Ligand Exhibiting Photoinduced Valence Tautomerism

Dai

Kanegawa

et al. 2013

Eur J Inorg Chem

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“…Taken together, our data suggested that iron acted as a metal-to-ligand-charge-transfer (MLCT), allowing the electrons of the negatively charged hydroxyl groups to be delocalized over both ligands (Barreto et al 2008;Alberding et al 2011). Thus, the enlarged electronic system caused black colour formation and UV absorbance at 570 nm.…”

Section: Ferric Iron In Complexmentioning

confidence: 71%

Potential of insect proteins for food and feed : Effect of endogenous enzymes and iron-phenolic complexation

Janssen¹

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Insects have been identified as excellent alternative source of proteins due to their high protein content. The acceptance of insects increases when used as ingredient in an invisible manner and hence grinding is necessary. Off-colour formation occurs upon grinding larvae, which can hamper their potential use as ingredient for food and feed. The aim of this thesis was to investigate potential of insect larvae as protein source, the mechanisms responsible for the browning or blackening of larvae during grinding, and its impact on protein functionality. This was investigated for the larvae of three species: Tenebrio molitor, Alphitobius diaperinus and Hermetia illucens. The specific Kp factor of 4.76±0.09 was determined for the three species to determine protein content based on nitrogen, and 5.60±0.39 after protein extraction and purification. Thus, the general Kp factor of 6.25, used until now, overestimated the protein content in insects. Off-colour formation upon grinding was caused by both enzymatic and non-enzymatic browning. Phenoloxidase was found to be mainly responsible for browning in T. molitor and likely in A. diaperinus, whereas iron-phenolic complexation likely contributed to the black colour in H. illucens. A model system of L-DOPA and iron was used to elucidate the structures of the iron-L-DOPA complexes by mass spectrometry. Enzymatic browning did not influence the solubility of the proteins of all three species. Upon in-vitro hydrolysis by pepsin and trypsin, soluble proteins from H. illucens were more digestible compared to those of T. molitor and A. diaperinus. Phenoloxidase activity during processing negatively affected in-vitro pepsin hydrolysis. Besides phenoloxidase activity, also endogenous proteases remained active at pH 8 in extracts of insect larvae. Summarizing, endogenous enzyme activities and iron complexation should be taken into account for future application, as well as the specific Kp factor to prevent overestimation of the protein content of insects. v 7 CONTENTS Chapter 1 General introduction Chapter 2 Nitrogen-to-protein conversion factors for three edible insects: Tenebrio molitor, Alphitobius diaperinus and Hermetia illucens Chapter 3 Involvement of phenoloxidase in browning during grinding of Tenebrio molitor larvae Chapter 4 Iron-polyphenol complexes cause blackening upon grinding Hermetia illucens (black soldier fly) larvae Chapter 5 Effect of endogenous phenoloxidase on protein solubility and digestibility after processing of Tenebrio molitor, Alphitobius diaperinus and Hermetia illucens

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“…Moreover, these techniques have helped elucidate Tyr oxidation in beta-amyloid peptide [212], the formation of oxidation products that have distinctive bands such as quinones, and metal ion complexes with these species [209,213].…”

Section: Spectroscopic Methods Of Quantifying Tyr Oxidation Productsmentioning

confidence: 99%

Exploring oxidative modifications of tyrosine: An update on mechanisms of formation, advances in analysis and biological consequences

Houée-Levin⊥

Bobrowski

Horáková

et al. 2015

Free Radical Research

103

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Protein oxidation is increasingly recognised as an important modulator of biochemical pathways controlling both physiological and pathological processes. While much attention has focused on cysteine modifications in reversible redox signalling, there is increasing evidence that other protein residues are oxidised in vivo with impact on cellular homeostasis and redox signalling pathways. A notable example is tyrosine, which can undergo a number of oxidative post-translational modifications to form 3-hydroxy-tyrosine, tyrosine crosslinks, 3-nitrotyrosine and halogenated tyrosine, with different effects on cellular functions. Tyrosine oxidation has been studied extensively in vitro, and this has generated detailed information about the molecular mechanisms that may occur in vivo. An important aspect of studying tyrosine oxidation both in vitro and in biological systems is the ability to monitor the formation of oxidised derivatives, which depends on a variety of analytical techniques. While antibody-dependent techniques such as ELISAs are commonly used, these have limitations, and more specific assays based on spectroscopic or spectrometric techniques are required to provide information on the exact residues modified and the nature of the modification. These approaches have helped understanding of the consequences of tyrosine oxidation in biological systems, especially its effects on cell signalling and cell dysfunction, linking to roles in disease. There is mounting evidence that tyrosine oxidation processes are important in vivo and can contribute to cellular pathology.

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Raman, IR, UV–vis and EPR characterization of two copper dioxolene complexes derived from L-dopa and dopamine

Cited by 46 publications

References 20 publications

A Switchable Complex Ligand Exhibiting Photoinduced Valence Tautomerism

A Switchable Complex Ligand Exhibiting Photoinduced Valence Tautomerism

Potential of insect proteins for food and feed : Effect of endogenous enzymes and iron-phenolic complexation

Exploring oxidative modifications of tyrosine: An update on mechanisms of formation, advances in analysis and biological consequences

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