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- Phenolic compounds: a novel approach to reduce egg allergenicity?Publication . Vapor, Alcides; Tomaz, Cândida T.; Mendonça, AntónioHen's egg allergy has been climbing in all countries due to eggs ubiquity in foodstuffs. This allergy is an IgE mediated reaction that affects mainly infants and young children. So far, the processes used to decrease the allergenicity of egg proteins, such as cooking, thermal processing, storage and enzymatic digestion have not been totally effective. Previous studies demonstrated that proteins form complexes with phenolic compounds, so the aim of this work was to analyze the effect of these compounds in ovalbumin (OVA) conformation and its possible application to reduce eggs allergenicity. OVA was incubated at different temperatures with phenolic compounds (caffeic, chlorogenic, ferulic, gallic and tannic acids; resveratrol and quercetin) and was analyzed by circular dichroism (CD), Attenuated Total Reflection–Fourier Transform Infra-Red (ATRFTIR) spectroscopy and fluorescence. Changes in the secondary structure of OVA were evidenced by CD and ATR-FTIR. Also, protein fluorescence decreased with increasing concentrations of phenolic compounds. The thermodynamic analysis suggested that electrostatic interactions are important in the binding process, and the quenching mechanism occur by contact. This was confirmed by docking where the phenolic compounds bind specifically to some regions of the protein, including those with the allergenic epitopes.
- Interactions of Phenolic Compounds with OvalbuminPublication . Vapor, Alcides; Tomaz, Cândida T.; Mendonça, AntónioOvalbumin (OVA) is the major protein in egg white and can cause allergy mainly in infants and young children [1]. Egg allergy is an IgE mediated reaction and is one the most common food allergies. So far, the avoidance of the egg has been the unique way to prevent this allergy [2]. It is well known that phenolic compounds can bind to proteins promoting structural and functional changes. In this work, the interactions between OVA and the phenolic compounds were studied through spectroscopic techniques (fluorescence, circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR)) and docking. OVA solutions were incubated at different temperatures and times, with different phenolic compounds prepared with the same buffer solution (Gallic, Caffeic, Ferulic, Chlorogenic and Tannic Acids, Resveratrol and Quercetin). Results indicate that OVA's structure was affected by the binding of phenolic compounds. CD and FTIR experiments showed changes in the secondary structure of OVA, originated by the conversion of α-helix into β-sheets [1]. Fluorescence spectra demonstrated that phenolics are quenchers of fluorescent aminoacids (Tyrosine, Phenylalanine and Tryptophan) meaning that interactions occur directly or near these aminoacids. Fluorescence results also suggest that these interactions are electrostatic and thermodynamically favorable (∆G<0). Docking studies showed that the tested phenolic compounds can interact directly with OVA epitopes, or with its neighbors, thus avoiding the IgE binding. Therefore, the phenolic compounds can be used as a strategy for reducing egg allergy in foods.
- Ovalbumin Structural Changes by Phenolic Compounds InteractionsPublication . Vapor, Alcides; Tomaz, Cândida T.; Mendonça, AntónioOvalbumin (OVA) is the most prevalent protein in egg white and, represents the major allergen from avian egg white that causes IgE-mediated food allergic reactions particularly in children. It has been shown that phenolic compounds interact with proteins by a single or multipoint mechanism, promoting structural and functional changes. Moreover, the interaction of some allergens with polyphenols, led to permanent modification of the tertiary structure of the allergen, which can result in a reduction in its IgE-binding capacity. This work aimed to analyse the effect of phenolic compounds (Gallic, Caffeic, Ferulic, Chlorogenic and Tannic Acids, Resveratrol and Quercetin) on the native structure of OVA, using Circular Dichroism (CD), fluorescence and Fourier transform infrared spectroscopy (FTIR). The phenolic compounds were incubated with OVA at different times, concentrations and temperatures. Changes in OVA secondary and tertiary structures were increasingly induced with increasing temperatures by the phenolic compound. Also, for a constant temperature, the changes found in OVA structure increased with the phenolic compounds concentration. The results show that the interactions between phenolic compounds and OVA result in complexes (phenolics – OVA) where OVA native structure is changed. This is likely to affect epitopes and hence OVA allergenicity.
- Interactions of phenolic compounds with ovalbumin: a spectroscopic approachPublication . Vapor, Alcides; Tomaz, Cândida T.; Mendonça, AntónioOvalbumin (OVA) is the major protein in egg white and can cause allergy mainly in infants and young children. Egg allergy is an IgE mediated reaction and is one the most common food allergies. So far, the avoidance of the egg has been the unique way to prevent this allergy. It is well known that phenolic compounds can bind to proteins promoting structural and functional changes and, phenolic compounds are been recognized as having a potent antioxidant, anti-inflammatory and antitumoral activity. In this work, the interactions between OVA and the phenolic compounds were studied through spectroscopic techniques (fluorescence, circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR)) and docking. spectroscopy (FTIR)) and docking.
- Processes for reducing egg allergenicity: Advances and different approachesPublication . Vapor, Alcides; Mendonça, A.J.G. De; Tomaz, C.Egg is a versatile ingredient and ubiquitous food. Nevertheless, egg proteins are a common cause of allergy mainly in childhood. Until now, egg eviction has been the best way to prevent this disorder, however, processed food can contribute to mitigate allergies and to guarantee life quality of allergic individuals. This review focuses on discussing and highlighting recent advances in processes to reduce egg allergenicity as well as new approaches to egg allergy management. In recent times, different methods have been developed to reduce egg allergies, by hiding the epitopes or changing the native or conformational structure of the proteins. Despite processing food has not yet been a solution to completely remove the allergenic potential of egg proteins, innovative strategies, such as addition of phenolic compounds, have been developed with promising results.