Food Antioxidants and Their Interaction with Human Proteins

BeStSel: analysis site for protein CD spectra-2025 update

Circular dichroism (CD) spectroscopy is a widely used technique to characterize the secondary structure composition of proteins. We have developed the Beta Structure Selection (BeStSel) method (PNAS, 112, E3095), which solves the main problem of protein CD spectroscopy-namely, the spectral variability of β-structures. The BeStSel web server utilizes this method to provide tools to the community for CD spectrum analysis. BeStSel uniquely provides information on eight secondary structure components, including parallel β-structure and antiparallel β-sheets with three different twist groups. It outperforms all available methods in accuracy and information content, and is also able to predict protein folds down to the topology/homology level of the CATH classification. The algorithm has been further developed, and the accuracy of the estimation of the secondary structure elements is improved by 0.7% as an average on the reference dataset. A new module of the web server calculates protein stability from the thermal denaturation profile followed by CD. Secondary structure calculations of uploaded PDB and mmcif files support the experimental verification of MD simulations and AlphaFold models by CD spectroscopy. Well-proven modules for disorder-order classification and extinction coefficient calculation continue to work. The BeStSel server is freely accessible at https://bestsel.elte.hu.

Recent developments in the design of functional derivatives of edaravone and exploration of their antioxidant activities

Edaravone, a pyrazalone derivative, is an antioxidant and free radical scavenger used to treat oxidative stress-related diseases. It is a proven drug to mitigate conditions prevailing to oxidative stress by inhibiting lipid peroxidation, reducing inflammation, and thereby preventing endothelial cell death. In recent years, considerable interest has been given by researchers in the derivatization of edaravone by adding varieties of substituents of versatile steric and functional properties to improve its antioxidant and pharmacological activity. This review accounts all the important methods developed for the derivatization of edaravone and the impacts of the structural modifications on the antioxidant activity of the motif.

Effect of wet media milling on starch-quercetin complex: Enhancement of Pickering emulsifying ability and oxidative resistance

This research explored the effect of media milling on complexation of corn starch (CS) and quercetin (QC), interaction mechanism and Pickering emulsifying ability of corn-quercetin (CS-QC) complex. CS-QC with QC/CS ratio of 1:24 had the highest encapsulation efficiency of 76.00 ± 1.30 %. Average volume-mean diameter, average whole molecular size (Rh) and debranchedamylopectinchain length of CS-QC were significantly decreased after milling. Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) spectra confirmed the complexation between CS and QC. Emulsifying capacity and emulsion stability of Pickering emulsion stabilized by 5 % CS-QC complex particles after 120 min milling reached 100.00 % and 100.00. Pickering emulsions stabilized by these complex particles demonstrated superior oxidative stability. These results demonstrated that media milling could be an efficient physical approach to obtain starch-polyphenol complex by enhancing non-covalent interactions, which could not only be used as food-grade Pickering emulsifiers, but also retard lipid oxidation.

Phycocyanobilin is a new binding partner of human alpha-2-macroglobulin that protects the protein against oxidative stress

Under simulated physiological conditions, this study investigates the interaction between nutraceutical phycocyanobilin (PCB) and the universal anti-protease protein human alpha-2-macroglobulin (α2M). Extensive molecular docking analyses on multiple α2M conformations, spectroscopic techniques, and α2M activity assays were utilized to examine the complex formation. The results revealed that for every protein conformation, two high energy binding sites exist: the first, conformationally independent, at the interface region between two monomer chains and the second, conformationally dependent, in the pocket composed of amino acids from four distinct domains (TED, RBD, CUB, and MG2) of the single protein chain. Spectrofluorimetric measurements indicated a moderate affinity between α2M and PCB with a moderately high binding constant of 6.3 × 105 M-1 at 25 °C. The binding of PCB to α2M resulted in minor changes in the secondary structure content of α2M. Furthermore, PCB protected α2M from oxidation and preserved its anti-protease activity in the oxidative environment. These findings suggest that PCB binding could indirectly impact the body's response to oxidative stress by influencing α2M's role in controlling enzyme activity during the inflammatory process.Communicated by Ramaswamy H. Sarma.

Direct and Sensitive Electrochemical Determination of Total Antioxidant Capacity in Foods Using Nanochannel-Based Enrichment of Redox Probes

Simple and sensitive determination of total antioxidant capacity (TAC) in food samples is highly desirable. In this work, an electrochemical platform was established based on a silica nanochannel film (SNF)-modified electrode, facilitating fast and highly sensitive analysis of TAC in colored food samples. SNF was grown on low-cost and readily available tin indium oxide (ITO) electrode. Fe3+-phenanthroline complex-Fe(III)(phen)3 was applied as the probe, and underwent chemical reduction to form Fe2+-phenanthroline complex-Fe(II)(phen)3 in the presence of antioxidants. Utilizing an oxidative voltage of +1 V, chronoamperometry was employed to measure the current generated by the electrochemical oxidation of Fe(II)(phen)3, allowing for the assessment of antioxidants. As the negatively charged SNF displayed remarkable enrichment towards positively charged Fe(II)(phen)3, the sensitivity of detection can be significantly improved. When Trolox was employed as the standard antioxidant, the electrochemical sensor demonstrated a linear detection range from 0.01 μM to 1 μM and from 1 μM to 1000 μM, with a limit of detection (LOD) of 3.9 nM. The detection performance is better that that of the conventional colorimetric method with a linear de range from 1 μM to 40 μM. Owing to the anti-interfering ability of nanochannels, direct determination of TAC in colored samples including coffee, tea, and edible oils was realized.

Design of triple-layer films with blackseed protein as dispersion or emulsion

The aim of study was to produce the blackseed protein for applications as a protein dispersion alone or an emulsifier to design of multi-layer film based on furcellaran and chitosan. The protein extraction of blackseed by-product resulted in a blackseed by-product protein isolate (BBPI) with a yield of 73% protein. The obtained BBPI resulted in a high polyphenols content (1543 mg/ml), antioxidant property (DPPH, 67%) and emulsification properties (encapsulation up to 96%), leading to a stable emulsions at pH 10 and 12. For the first time, innovative, active triple-layer films have been developed in the 1st furcellaran layer with BBPI stabilised emulsion or BBPI aqueous extract alone, followed by a 2nd layer of furcellaran and citric acid matrix, and a 3rd layer of chitosan and gelatin matrix. Compared to the control, the tested films showed improved the water behaviour, UV-Vis barrier and increased antioxidant activity for the DPPH parameter (>70%).

Human Hemoglobin and Antipsychotics Clozapine, Ziprasidone and Sertindole: Friends or Foes?

Packed with hemoglobin, an essential protein for oxygen transport, human erythrocytes are a suitable model system for testing the pleiotropic effects of lipophilic drugs. Our study investigated the interaction between antipsychotic drugs clozapine, ziprasidone, sertindole, and human hemoglobin under simulated physiological conditions. Analysis of protein fluorescence quenching at different temperatures and data obtained from the van't Hoff diagram and molecular docking indicate that the interactions are static and that the tetrameric human hemoglobin has one binding site for all drugs in the central cavity near αβ interfaces and is dominantly mediated through hydrophobic forces. The association constants were lower-moderate strength (~10⁴ M^-1), the highest observed for clozapine (2.2 × 10⁴ M^-1 at 25 °C). The clozapine binding showed "friendly" effects: increased α-helical content, a higher melting point, and protein protection from free radical-mediated oxidation. On the other hand, bound ziprasidone and sertindole had a slightly pro-oxidative effect, increasing ferrihemoglobin content, a possible "foe". Since the interaction of proteins with drugs plays a vital role in their pharmacokinetic and pharmacodynamic properties, the physiological significance of the obtained findings is briefly discussed.