Increased stability and intracellular antioxidant activity of chlorogenic acid depend on its molecular interaction with wheat gluten hydrolysate

Study on the interaction and functional properties of Dolichos lablab L. protein-tea polyphenols complexes

Tea polyphenols (TP) and plant proteins are significant materials in the food industry, the interactions between them are beneficial for their stability, functional properties, and biological activity. In this study, the mechanism and interaction between Dolichos lablab L. protein (DLP) obtained from nine treatments and three tea polyphenol monomers (EGCG, ECG, and EGC) were investigated. The results showed that the fluorescence of DLP was noticeably quenched and exhibited static quenching after the addition of polyphenols. DLP exhibited 1-2 binding sites for EGCG and ECG, but weakly binding to EGC (<1). The binding sites of DLP-TP were found to be in close proximity to the tyrosine residues, primarily interacting through hydrophobic interactions, van der Waals forces, and hydrogen bonds. The antioxidant capacity of DLP-TP compound was significantly improved after digestion. ECG showed a strong resistance to intestinal digestion. Compared with ECG (653.456 μg/mL), the content of free tea polyphenols of 20/40 kHz-ECG after digestion was 732.42 μg/mL. DLP-TP complexes significantly improved the storage stability, thermal stability, and bioaccessibility of tea polyphenols. The interaction between TP and DLP, as a protein-polyphenol complex, has great potential for application in preparing emulsion delivery systems due to their antioxidant activity and improved stability.

Molecular Mechanisms and Applications of Polyphenol-Protein Complexes with Antioxidant Properties: A Review

Proteins have been extensively studied for their outstanding functional properties, while polyphenols have been shown to possess biological activities such as antioxidant properties. There is increasing clarity about the enhanced functional properties as well as the potential application prospects for the polyphenol-protein complexes with antioxidant properties. It is both a means of protein modification to provide enhanced antioxidant capacity and a way to deliver or protect polyphenols from degradation. This review shows that polyphenol-protein complexes could be formed via non-covalent or covalent interactions. The methods to assess the complex's antioxidant capacity, including scavenging free radicals and preventing lipid peroxidation, are summarized. The combination mode, the type of protein or polyphenol, and the external conditions will be the factors affecting the antioxidant properties of the complexes. There are several food systems that can benefit from the enhanced antioxidant properties of polyphenol-protein complexes, including emulsions, gels, packaging films, and bioactive substance delivery systems. Further validation of the cellular and in vivo safety of the complexes and further expansion of the types and sources of proteins and polyphenols for forming complexes are urgently needed to be addressed. The review will provide effective information for expanding applications of proteins and polyphenols in the food industry.

Extraction and Identification of Antioxidant Ingredients from Cyclocarya paliurus (Batal.) Iljinsk Using UHPLC-Q-Orbitrap-MS/MS-Based Molecular Networking

Cyclocarya paliurus (Batal.) Iljinskaja (LCP) leaves have been widely employed in food and traditional medicine for treating hyperlipidaemia and its complications, possibly owing to their antioxidant properties. The aim of the present study is to identify the chemical ingredients of antioxidant extracts from LCP by using UHPLC-Q-Orbitrap-MS/MS-based molecular networking, a very recent and useful tool for annotation of chemical constituents in mixtures. The extraction conditions of antioxidant extracts from LCP were optimised by single-factor analysis and response surface methodology (RSM). The optimised conditions were a methanol concentration of 32%, a liquid-to-solid ratio of 0.4 ml/mg, an extraction temperature of 25°C, and an extraction time of 32 min. Under these conditions, the antioxidant yield was 516.20 ± 28.52 μmol TE/ml. The main active ingredients in the antioxidants were identified by UHPLC-Q-Exactive Orbitrap-MS-based molecular networking. In total, 42 compounds were identified, including 20 flavonoids, 16 quinic acid derivatives, 4 caffeoyl derivatives, and 2 coumaroyl derivatives. The findings of the present work suggest that LCP could be a suitable source of natural antioxidant compounds, which might be applicable in the development of potential pharmaceutical drugs targeting diseases related to oxidative stress.

Multispectroscopic and Computational Investigations on the Binding Mechanism of Dicaffeoylquinic Acids with Ovalbumin

Recently, studies on the interactions between ovalbumin (OVA) and polyphenols have received a great deal of interest. This study explored the conformational changes and the interaction mechanism of the binding between OVA and chlorogenic acid (CGA) isomers such as 3,4-dicaffeoylquinic acids (3,4-diCQA), 4,5-dicaffeoylquinic acids (4,5-diCQA), and 3,5-dicaffeoylquinic acids (3,5-diCQA) using multispectroscopic and in silico analyses. The emission spectra show that the diCQAs caused strong quenching of OVA fluorescence under different temperatures through a static quenching mechanism with hydrogen bond (H-bond) and van der Waals (vdW) interactions. The values of binding constants (OVA-3,4-diCQA = 6.123 × 10⁵, OVA-3,5-diCQA = 2.485 × 10⁵, OVA-4,5-diCQA = 4.698 × 10⁵ dm³ mol^-1 at 298 K) suggested that diCQAs had a strong binding affinity toward OVA, among which OVA-3,4-diCQA exhibits higher binding constant. The results of UV-vis absorption and synchronous fluorescence indicated that the binding of all three diCQAs to OVA induced conformational and micro-environmental changes in the protein. The findings of molecular modeling further validate the significant role of vdW force and H-bond interactions in ensuring the stable binding of OVA-diCQA complexes. Temperature-dependent molecular dynamics simulation studies allow estimation of the individual components that contribute to the total bound free energy value, which allows evaluation of the nature of the interactions involved. This research can provide information for future investigations on food proteins' physicochemical stability and CGA bioavailability in vitro or in vivo.

The use of ecological analytical tools as an unconventional approach for untargeted metabolomics data analysis: the case of Cecropia obtusifolia and its adaptive responses to nitrate starvation

Plant metabolomics studies haves revealed new bioactive compounds. However, like other omics disciplines, the generated data are not fully exploited, mainly because the commonly performed analyses focus on elucidating the presence/absence of distinctive metabolites (and/or their precursors) and not on providing a holistic view of metabolomic changes and their participation in organismal adaptation to biotic and abiotic stress conditions. Therefore, spectral libraries generated from Cecropia obtusifolia cell suspension cultures in a previous study were considered as a case study and were reanalyzed herein. These libraries were obtained from a time-course experiment under nitrate starvation conditions using both electrospray ionization modes. The applied methodology included the use of ecological analytical tools in a systematic four-step process, including a population analysis of metabolite α diversity, richness, and evenness (i); a chemometrics analysis to identify discriminant groups (ii); differential metabolic marker identification (iii); and enrichment analyses and annotation of active metabolic pathways enriched by differential metabolites (iv). Our species α diversity results referring to the diversity of metabolites represented by mass-to-charge ratio (m/z) values detected at a specific retention time (rt) (an uncommon way to analyze untargeted metabolomic data) suggest that the metabolome is dynamic and is modulated by abiotic stress. A total of 147 and 371 m/z_rt pairs was identified as differential markers responsive to nitrate starvation in ESI^- and ESI⁺ modes, respectively. Subsequent enrichment analysis showed a high degree of completeness of biosynthetic pathways such as those of brassinosteroids, flavonoids, and phenylpropanoids.

Ovalbumin coated Fe3O4 nanoparticles as a nanocarrier for chlorogenic acid to promote the anticancer efficacy on MDA-MB-231 cells

Chlorogenic acid (5-CQA), a phenolic acid abundant in plants and herbs, has various beneficial effects on human health. However, 5-CQA undergoes biotransformation during gastrointestinal digestion, which affects its biological accessibility....

Wheat grain phenolics: a review on composition, bioactivity, and influencing factors

Wheat (Triticum aestivum L.) is a widely cultivated crop and one of the most commonly consumed food grains in the world. It possesses several nutritional elements. Increasing attention to wheat grain phenolics bioactivity is due to the increasing demand for foods with natural antioxidants. To provide a comprehensive understanding of phenolics in wheat grain, this review first summarizes the phenolics' form and distribution and the phenolic components identified in wheat grain. In particular, the biosynthesis path for phenolics is discussed, identifying some candidate genes involved in the biosynthesis of phenolic acids and flavonoids. After discussing the methods for determining antioxidant activity, the effect of genotypes, environmental conditions, and cultivation systems on grain phenolic component content are explored. Finally, the bioavailability of phenolics under different food processing method are reported and discussed. Future research is recommended to increase wheat grain phenolic content by genetic engineering, and to improve its bioavailability through proper food processing. © 2021 Society of Chemical Industry.

Accurate Quantification of Sulfonamide Metabolites in Goat Meat: A New Strategy for Minimizing Interaction between Sheep Serum Albumin and Sulfonamide Metabolites

To date, the determination of sulfonamide metabolites in animal-derived food has universal disadvantages of low throughput and no integrated metabolites involved. In this study, a powerful and reliable strategy for high-throughput screening of sulfonamide metabolites in goat meat was proposed based on an aqueous two-phase separation procedure (ATPS) combined with ultrahigh-performance liquid chromatography quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap). Noncovalent interactions including van der Waals force, hydrogen bonding, and hydrophobic effect were determined to be staple interactions between the sulfonamide metabolites and sheep serum albumin by fluorescence spectroscopy and molecular docking technology, and an 80% acetonitrile-water solution/(NH₄)₂SO₄ was used as ATPS in order to release combined sulfonamide metabolites and minimize the influence of sheep serum albumin. Sulfonamide metabolites in the matrix were screened based on a mechanism of mass natural loss and core structure followed by identification combined with the pharmacokinetic. The developed strategy was validated according to EU standard 2002/657/EC with CCα ranging from 0.07 to 0.98 μg kg^-1, accuracy recovery with 84-107%, and RSDs lower than 8.9%. Eighty seven goat meat samples were used for determination of 26 sulfonamides and 8 potential metabolites. On the basis of the established innovative process, this study has successfully implemented the comprehensive detection of sulfonamide metabolites, including N⁴-acetylated substitution, N⁴-hydroxylation, 4-nitroso, azo dimers, oxidized nitro, N⁴ monoglucose conjugation, β-d-glucuronide, and N-4-aminobenzenesulfonyl metabolites, which were shown to undergo oxidation, hydrogenation, sulfation, glucuronidation, glucosylation, and O-aminomethylation.

Lanthanum (La) improves growth, yield formation and 2-acetyl-1-pyrroline biosynthesis in aromatic rice (Oryza sativa L.)

BACKGROUND

Lanthanum (La) is a rare earth element that can influence plant growth and development. However, the effect of La on growth, yield formation and 2-acetyl-1-pyrroline (2-AP, a key compound responsible for the aroma of rice) biosynthesis in aromatic rice (Oryza sativa L. subsp. japonica Kato) has not been reported. Therefore, the present study investigated the effects of La on growth, photosynthesis, yield formation and 2-AP biosynthesis in aromatic rice through three experiments.

RESULTS

Two pot experiments and a two-year field trial were conducted with different rates of La application (20-120 LaCl3 mg kg-1 and 12 kg ha-1 LaCl3), and treatments without La application were used as controls. The results showed that the application of LaCl3 at 80 and 100 mg kg-1 and at 12 kg ha-1 greatly increased the 2-AP content (by 6.45-43.03%) in aromatic rice seedlings and mature grains compared with the control. The La treatments also increased the chlorophyll content, net photosynthetic rate and total aboveground biomass of rice seedlings. Higher antioxidant enzyme (superoxide, peroxidase, and catalase) activity was detected in the La treatments than in the control. The La treatments also increased the grain yield, grain number per panicle and seed-setting rate of aromatic rice relative to the control. Moreover, the grain proline and γ-aminobutyric acid contents and the activity of betaine aldehyde dehydrogenase significantly decreased under the La treatment. The application of La to soil enhanced the activity of proline dehydrogenase by 20.62-56.95%.

CONCLUSIONS

La improved the growth, yield formation and 2-AP content of aromatic rice and enhanced 2-AP biosynthesis by increasing the conversion of proline to 2-AP and decreasing the conversion of GABald to GABA.

Antioxidant activities of chlorogenic acid derivatives with different acyl donor chain lengths and their stabilities during in vitro simulated gastrointestinal digestion

In this study, chlorogenic acid (CA) was acylated with vinyl esters of different carbon chain lengths under the action of the lipase Lipozyme RM. Five CA derivatives (C2-CA, C4-CA, C6-CA, C8-CA, and C12-CA) with different lipophilicities were obtained, and their digestive stabilities and antioxidant activities were evaluated. The lipophilicities were positively correlated with the digestive stabilities of CA derivatives. The antioxidant activities of CA derivatives did not change with the reduction of phenolic hydroxyl groups, and their capacity to scavenge 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+•) and 1,1-diphenyl-2-picrylhydrazyl (DPPH•) were similar to those of CA. In cellular antioxidant activity (CAA) tests, it was found that the capacity of these derivates to cross cell membranes were enhanced upon enhancing lipophilicity, and their antioxidant activities were improved. C12-CA showed the best antioxidant activity with a median effective dose (EC50) of 9.40 μg/mL, which was significantly lower than that of CA (i.e., 29.08 μg/mL).

Investigation into the site-specific binding interactions between chlorogenic acid and ovalbumin using multi-spectroscopic and in silico simulation studies

The binding interactions of bioactive compounds with proteins are of great importance in the food, biochemistry and pharmaceutical fields. Herein, the binding mechanisms between 5-O-caffeoylquinic acid (5-CQA) and ovalbumin (OVA) were investigated by multi-spectroscopic studies combined with docking and molecular dynamics (MD) simulations. The emission intensity of OVA was quenched by 5-CQA and Stern-Volmer analysis indicated the existence of a static suppression by OVA-5-CQA complex formation. Thermodynamic parameters revealed that the formation of complex was spontaneously driven by electrostatic and hydrogen-bonding interactions. Circle dichroism analyses showed that 5-CQA decreased the α-helix content of OVA structure from 58.05% to 54.32% upon increased OVA:5-CQA ratio to 1:3. Molecular docking results suggested 5-CQA forms hydrogen bond interactions with N88, T91, K92, N94, S98, F99, S100 and L101 residues of OVA. The experimental values were in good agreement with the calculated binding free energy values obtained by MD simulation (R² = 0.89).Communicated by Ramaswamy H. Sarma.