Ultrasound-assisted complexation of Millettia speciosa by-product protein with polyphenols: improved structural properties, antioxidant and hypoglycemic activities, and gut microbiota modulation.
Aug 2026· Food Chemistry· Vol 526, pp.
150839
· 0 citations· 63 references
Medicine
TL;DR
This study utilized ultrasound-assisted technology to form non-covalent complexes of polyphenols with Millettia speciosa by-product protein, offering a sustainable strategy for its use in functional foods and biomaterials.
Abstract
This study utilized ultrasound-assisted technology to form non-covalent complexes of polyphenols with Millettia speciosa by-product protein (MSCP). Ultrasound disrupted protein aggregates into a porous network, increasing surface area. Polyphenol binding shifted protein structure from α-helix to β-sheet and enhanced hydrogen bonding. The complexes showed strong antioxidant and hypoglycemic activities, with the tannic acid (TA) complex comparable to vitamin C in radical scavenging and to acarbose in enzyme inhibition under the tested conditions. Fermentation experiments revealed the modified proteins enriched beneficial bacteria (e.g., Bacteroidetes, Phascolarctobacterium), increased microbial diversity, and showed predicted enrichment of metabolic pathways. The quercetin (QR) complex behaved similarly to inulin, while the TA complex promoted beneficial bacteria and suppressed pathogens. This approach improves MSCP's functionality, offering a sustainable strategy for its use in functional foods and biomaterials.
Polysaccharides are complex biopolymers of monosaccharide units linked through glycosidic bonds that serve roles in energy storage and diverse biological functions in living organisms. Agricultural by-products, including fruit peels, pomace, seeds, cereal brans, and plant residues, are abundant, renewable sources of bioactive polysaccharides with applications in the food, nutraceutical, and pharmaceutical sectors. These residual materials contain functional polysaccharides with antioxidant, immunomodulatory, prebiotic, and hypoglycemic properties. Conventional extraction methods have limitations, including prolonged processing times, excessive energy and solvent consumption, thermal degradation of heat-labile compounds, and scalability challenges. To address these constraints, ultrasound-assisted enzymatic extraction (UAEE) has emerged as a green extraction technology combining ultrasonic cavitation-induced mechanical disruption of plant cell walls with enzymatic hydrolysis for selective polysaccharide liberation. This review explains how enzyme-assisted extraction improves release by hydrolyzing cell-wall barriers (cellulase, hemicellulase, pectinase, and protease), often requiring optimized multi-enzyme cocktails and multivariate mixture designs to avoid antagonism. UAEE enhances extraction efficiency, reduces processing time, and operates under mild conditions that preserve structural integrity and bioactivity. Extraction performance is governed by the interplay of enzyme loading, pH, temperature, ultrasonic power, treatment time, and solid–liquid ratio, each of which displays a substrate-dependent optimum beyond which yield or structural integrity declines. Because the reported optima differ markedly with the botanical source and the target polysaccharide, they are best regarded as matrix-specific windows that require re-optimization for each feedstock rather than as universal set points. It evaluates UAEE applications, analyzes effectiveness across agricultural substrates, examines optimization methodologies, and discusses extracted polysaccharides, providing an overall sustainable framework.
This study elucidates the non-covalent interaction mechanism between hemp seed globulin (GLB), a plant protein rich in arginine, and tannic acid (TA) via combined multispectral analysis and molecular simulations. TA adopts an amphipathic binding mode within a defined GLB pocket, driven mainly by hydrophobic forces and supplemented by hydrogen bonds and arginine-mediated cation-π interactions, which collectively drive an entropy-favorable spontaneous binding process (ΔH > 0, ΔS > 0). TA binding drives localized secondary structural adjustments and enhances conformational compactness of GLB. The resulting GLB-TA complex exhibits significantly improved antioxidant activity and emulsifying properties, alongside reduced in vitro digestibility. This work elucidates a specific interaction paradigm between high-arginine plant globulins and hydrolysable polyphenols, providing a mechanistic basis for clean-label plant protein modification and supporting sustainable functional food development, aligned with UN SDGs 3 (Good Health and Well-being) and 12 (Responsible Consumption and Production).
Y. Zhang, Xiao-Dong Tian, Zuoxing Di et al.· Food Chemistry· 0 citations
Teff (Eragrostis tef) is a gluten-free cereal and a valuable source for functional food. This study evaluated the physicochemical characteristics of teff flours and optimized ultrasound-assisted extraction of bioactive compounds. Ultrasonic-assisted extraction (UAE) was optimized using a Box–Behnken design (BBD), and the best extraction conditions were 50% ethanol, 60 °C, and 45 min, yielding 49.6 ± 0.028 mg gallic acid equivalents (GAE)/100 g dry weight (DW). High-performance liquid chromatography (HPLC) analysis revealed an abundant phenolic profile with compounds including epigallocatechin (2960.30 µg/g), epicatechin (113.55 µg/g), hesperidin (163.64 µg/g), and ferulic acid (41.79 µg/g). Prebiotic potential testing with Lactobacillus plantarum MIUG BL21 at 4 °C over 21 days indicated a concentration-dependent decrease in viability: at 5 mg/mL, mean counts decreased from 4.721 ± 0.049 to 2.349 ± 0.048 log colony-forming units (CFU)/mL; at 2.5 mg/mL, from 3.396 ± 0.095 to 0.500 ± 0.198 log CFU/mL; and at 1 mg/mL, counts became undetectable. Phytic acid degradation in teff extracts followed first-order kinetics, with half-lives of 1504.55, 752.30, and 300.91 min at 50, 70, and 90 °C, respectively. The activation energy of 39.07 kJ/mol confirmed the temperature dependence of the process and indicated an effective reduction in phytic acid. In conclusion, teff extracts may represent promising functional ingredients with antioxidant potential, support for probiotic viability, and reduced antinutritional factors.
Boyiza Samson Abebe, I. Aprodu, D. Istrati et al.· Foods· 0 citations
Bovine lactoferrin (BLF) is a milk-derived glycoprotein with diverse biological activities, including antimicrobial, antioxidant, and immunomodulatory functions, with potential for applications in functional foods and nutraceuticals. However, its practical utilization remains limited by key challenges: low efficiency of traditional extraction methods, poor gastrointestinal stability, and a narrow range of application forms. To address these issues, this study developed an integrated strategy spanning from efficient production to functional application. First, the Pichia pastoris expression system was optimized through signal peptide engineering and chaperone co-expression, achieving high-yield secretory production of recombinant BLF (rBLF) at 232.6 mg/L in shake-flask fermentation. Subsequently, rBLF was complexed with sodium alginate (NaAlg) via electrostatic self-assembly to form nanocomposites for gastrointestinal protection. The rBLF-NaAlg complex exhibited remarkable resistance to simulated gastric digestion, with only a 23.7% reduction in particle size, significantly lower than the 71.1% reduction observed for free rBLF. Furthermore, a three-dimensional hydrogel delivery system was constructed through microbial transglutaminase (MTGase)-catalyzed cross-linking. This system demonstrated encapsulation and sustained release of anthocyanins as a model bioactive compound. The gel structure and performance showed a clear enzyme concentration dependence: moderate cross-linking (<80 U/g) resulted in a uniform and dense network, enhancing encapsulation efficiency and providing controlled release. This work establishes a complete technological pathway from high-yield production and stabilization to functional expansion, demonstrating that rBLF can be transformed from a labile bioactive protein into a dual-functional material with both nutritional and delivery capabilities. This integrated strategy provides a viable solution for developing advanced BLF-based functional foods and nutraceutical delivery systems.
Jun-Qing Wang, Hao Yu, Kening Guo et al.· International Journal of Bio...· 0 citations
Grape stems (GSs), a key by-product of winemaking, are a rich source of bioactive polyphenols and have potential applications in functional foods, antioxidant additives, and cosmetics. In this study, the production of polyphenol-rich extracts from GS using an ultrasound-assisted, acid-catalyzed organosolv process was explored, using isopropanol as solvent. Sulfuric acid served as an effective catalyst for breaking down lignocellulosic material, and the process conditions were optimized using response surface methodology to maximize efficiency. Following an initial single-factor analysis, sulfuric acid and isopropanol concentrations were selected as the main variables. The optimal conditions—54% isopropanol and 1% sulfuric acid—yielded the highest polyphenol content (50.9 ± 4.4 mg caffeic acid equivalents per gram of dry mass). Further analysis using liquid chromatography–mass spectrometry revealed that acid catalysis significantly altered the polyphenolic composition of the extracts. These changes enhanced antioxidant potency, as expressed by the radical scavenging activity but not by the reducing power, while the exact nature of the newly formed compounds was unclear. Overall, the results provide useful insights into modifying the polyphenolic profile of grape stems to obtain extracts with improved antioxidant capacity, supporting more sustainable and value-added uses of winemaking by-products within biorefinery systems.
Romanos Karakalides, S. Grigorakis, S. Kallithraka et al.· Applied Sciences· 0 citations
Phenolic acid-chitosan complexes combine the antioxidant capacity of phenolic acids with the antibacterial activity of chitosan; however, their study has received limited attention due to challenges in synthesis. In this work, a selection of phenolic acids-4-hydroxybenzoic acid (HA), protocatechuic acid (PA), vanillic acid (VA), and ferulic acid (FA)-were complexed with chitosan in aqueous medium under thermal treatment. Elevated temperature markedly improved the solubility of phenolic acids, thereby enhancing complexation efficiency. XPS N 1 s analysis revealed that the balance between Free-NH₂ and ionic -NH₃+ is influenced by phenolic acid structure: phenolic hydroxyl groups promote ionic bonding, whereas methoxy groups hinder effective interaction due to hydrophobicity and steric bulk. This molecular-level programming translates into distinct macroscopic properties. The thermal stability and surface wettability of the complexes correlate with the ionic -NH₃+ content, while emulsifying performance, antioxidant capacity, antibacterial activity, and cytotoxicity are primarily governed by the intrinsic structural features of the phenolic acid ligands-such as the number of hydroxyl groups, the presence of methoxy substituents, and conjugated side chains. At concentrations relevant to antibacterial application (1.25-2.5 mg/mL), all complexes maintained >75% cell viability, indicating acceptable biocompatibility within the intended concentration range. These findings suggest a structure-property relationship in which phenolic acid substituents influence the interaction mode with chitosan and thereby affect the resulting physicochemical and biological properties. The thermal-assisted synthesis offers a simple, catalyst-free route to these multifunctional complexes, positioning them as promising candidates for applications in food preservation and related fields.
Heng Chen, Tingyuan Tan, Zhanpeng Zhang et al.· International Journal of Bio...· 0 citations
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