Simultaneous Ultrasound and Heat Enhance Functional Properties of Glycosylated Lactoferrin

Effect of electron beam irradiation on glycosylation reaction and structural characterization of whey isolate protein

BACKGROUND

Whey protein isolate (WPI) is a high-quality animal protein resource. The modification of WPI through physical, chemical and biological methods can substantially improve the functional properties of proteins. This study investigated the effect of electron beam irradiation (EBI) on the modification of WPI-xylose glycosylation.

RESULTS

The degree of grafting and browning revealed that EBI promoted WPI glycosylation. The maximum emission wavelength of intrinsic fluorescence was red-shifted and the fluorescence intensity was reduced, suggesting that irradiation induced the unfolding of the WPI structure, thereby promoting glycosylation. Fourier-transformed infrared spectroscopy revealed that the covalent binding of the conjugates occurred on the introduction of the hydrophilic groups, resulting in decreased surface hydrophobicity. When compared with conventional wet-heat glycosylation, irradiation-assisted glycosylation improved the emulsifying activity of WPI from 179.76 ± 0.83 to 277.83 ± 1.44 m2 g-1, and the emulsifying and rheological properties improved.

CONCLUSION

These results confirmed that EBI can increase the degree of WPI glycosylation and improve the functional properties of proteins, thereby laying a theoretical foundation for the further application of WPI. © 2024 Society of Chemical Industry.

Precision nutrition to reset virus-induced human metabolic reprogramming and dysregulation (HMRD) in long-COVID

SARS-CoV-2, the etiological agent of COVID-19, is devoid of any metabolic capacity; therefore, it is critical for the viral pathogen to hijack host cellular metabolic machinery for its replication and propagation. This single-stranded RNA virus with a 29.9 kb genome encodes 14 open reading frames (ORFs) and initiates a plethora of virus-host protein-protein interactions in the human body. These extensive viral protein interactions with host-specific cellular targets could trigger severe human metabolic reprogramming/dysregulation (HMRD), a rewiring of sugar-, amino acid-, lipid-, and nucleotide-metabolism(s), as well as altered or impaired bioenergetics, immune dysfunction, and redox imbalance in the body. In the infectious process, the viral pathogen hijacks two major human receptors, angiotensin-converting enzyme (ACE)-2 and/or neuropilin (NRP)-1, for initial adhesion to cell surface; then utilizes two major host proteases, TMPRSS2 and/or furin, to gain cellular entry; and finally employs an endosomal enzyme, cathepsin L (CTSL) for fusogenic release of its viral genome. The virus-induced HMRD results in 5 possible infectious outcomes: asymptomatic, mild, moderate, severe to fatal episodes; while the symptomatic acute COVID-19 condition could manifest into 3 clinical phases: (i) hypoxia and hypoxemia (Warburg effect), (ii) hyperferritinemia ('cytokine storm'), and (iii) thrombocytosis (coagulopathy). The mean incubation period for COVID-19 onset was estimated to be 5.1 days, and most cases develop symptoms after 14 days. The mean viral clearance times were 24, 30, and 39 days for acute, severe, and ICU-admitted COVID-19 patients, respectively. However, about 25-70% of virus-free COVID-19 survivors continue to sustain virus-induced HMRD and exhibit a wide range of symptoms that are persistent, exacerbated, or new 'onset' clinical incidents, collectively termed as post-acute sequelae of COVID-19 (PASC) or long COVID. PASC patients experience several debilitating clinical condition(s) with >200 different and overlapping symptoms that may last for weeks to months. Chronic PASC is a cumulative outcome of at least 10 different HMRD-related pathophysiological mechanisms involving both virus-derived virulence factors and a multitude of innate host responses. Based on HMRD and virus-free clinical impairments of different human organs/systems, PASC patients can be categorized into 4 different clusters or sub-phenotypes: sub-phenotype-1 (33.8%) with cardiac and renal manifestations; sub-phenotype-2 (32.8%) with respiratory, sleep and anxiety disorders; sub-phenotype-3 (23.4%) with skeleto-muscular and nervous disorders; and sub-phenotype-4 (10.1%) with digestive and pulmonary dysfunctions. This narrative review elucidates the effects of viral hijack on host cellular machinery during SARS-CoV-2 infection, ensuing detrimental effect(s) of virus-induced HMRD on human metabolism, consequential symptomatic clinical implications, and damage to multiple organ systems; as well as chronic pathophysiological sequelae in virus-free PASC patients. We have also provided a few evidence-based, human randomized controlled trial (RCT)-tested, precision nutrients to reset HMRD for health recovery of PASC patients.

Effect of ultrasonic assisted grafting on the structural and functional properties of mung bean protein isolate conjugated with maltodextrin through maillard reaction

Four different methods of maillard reaction including ultrasound (150 W, 10 min) assisted, classical wet heating (80 °C, 60min), moderate water bath heating (60°C, 12 to 30 h) and dry state method (60 °C, 79 % relative humidity and 48 h) were used to Mung bean protein isolate - Maltodexrtin conjugates (MPI-MD) preparation. The samples prepared under ultrasound and wet heating were chosen for further analysis according to degree of graft and UV-absorbance at 420 nm. Higher glycosylation at short time and lower browning were obtained under ultrasound treatment. Covalent attachment in conjugates confirmed by SDS-polyacrylamide gel electrophoresis. The structural analysis revealed prominent unfolding effect of ultrasound waves on the protein's molecules. The decrease of α-helix content was related to the exposure of buried amino group residues during reaction. Glycation of MPI under ultrasound caused changes in tertiary structure of protein and leads to decrease in the fluorescence intensity compared with native and wet heating treatments. FTIR spectra confirmed the conjugation of the MPI and MD and suggested that protein structure was changed and ultrasound promoted the graft reaction more than wet heating treatment. Conjugated MPI showed higher emulsification and solubility index than MPI, moreover the effect of ultrasonic waves on ameliorated functional properties was impressive than those for wet heating treatment. Overall, this study showed use of ultrasonication in maillard reaction was a suitable method for producing MPI- MD conjugates and improved the efficiency of graft reaction and functional properties of grafts.

Research Advances of Lactoferrin in Electrostatic Spinning, Nano Self-Assembly, and Immune and Gut Microbiota Regulation

Lactoferrin (LF) is a naturally present iron-binding globulin with the structural properties of an N-lobe strongly positively charged terminus and a cage-like structure of nano self-assembly encapsulation. These unique structural properties give it potential for development in the fields of electrostatic spinning, targeted delivery systems, and the gut-brain axis. This review will provide an overview of LF's unique structure, encapsulation, and targeted transport capabilities, as well as its applications in immunity and gut microbiota regulation. First, the microstructure of LF is summarized and compared with its homologous ferritin, revealing both structural and functional similarities and differences between them. Second, the electrostatic interactions of LF and its application in electrostatic spinning are summarized. Its positive charge properties can be applied to functional environmental protection packaging materials and to improving drug stability and antiviral effects, while electrostatic spinning can promote bone regeneration and anti-inflammatory effects. Then the nano self-assembly behavior of LF is exploited as a cage-like protein to encapsulate bioactive substances to construct functional targeted delivery systems for applications such as contrast agents, antibacterial dressings, anti-cancer therapy, and gene delivery. In addition, some covalent and noncovalent interactions of LF in the Maillard reaction and protein interactions and other topics are briefly discussed. Finally, LF may affect immunological function via controlling the gut microbiota. In conclusion, this paper reviews the research advances of LF in electrostatic spinning, nano self-assembly, and immune and gut microbiota regulation, aiming to provide a reference for its application in the food and pharmaceutical fields.

rocF affects the production of tetramethylpyrazine in fermented soybeans with Bacillus subtilis BJ3-2

BACKGROUND

Tetramethylpyrazine (TTMP) is a flavoring additive that significantly contributes to the formation of flavor compounds in soybean-based fermented foods. Over recent years, the application of TTMP in the food industry and medicine has been widely investigated. In addition, several methods for the industrial-scale production of TTMP, including chemical and biological synthesis, have been proposed. However, there have been few reports on the synthesis of TTMP through amino acid metabolic flux. In this study, we investigated genetic alterations of arginine metabolic flux in solid-state fermentation (SSF) of soybeans with Bacillus subtilis (B.subtilis) BJ3-2 to enhance the TTMP yield.

RESULTS

SSF of soybeans with BJ3-2 exhibited a strong Chi-flavour (a special flavour of ammonia-containing smelly distinct from natto) at 37 °C and a prominent soy sauce-like aroma at 45 °C. Transcriptome sequencing and RT-qPCR verification showed that the rocF gene was highly expressed at 45 °C but not at 37 °C. Moreover, the fermented soybeans with BJ3-2ΔrocF (a rocF knockout strain in B. subtilis BJ3-2 were obtained by homologous recombination) at 45 °C for 72 h displayed a lighter color and a slightly decreased pH, while exhibiting a higher arginine content (increased by 14%) than that of BJ3-2. However, the ammonia content of fermented soybeans with BJ3-2ΔrocF was 43% lower than that of BJ3-2. Inversely, the NH4+ content in fermented soybeans with BJ3-2ΔrocF was increased by 28% (0.410 mg/kg). Notably, the TTMP content in fermented soybeans with BJ3-2ΔrocF and BJ3-2ΔrocF + Arg (treated with 0.05% arginine) were significantly increased by 8.6% (0.4617 mg/g) and 18.58% (0.504 mg/g) respectively than that of the BJ3-2.

CONCLUSION

The present study provides valuable information for understanding the underlying mechanism during the TTMP formation process through arginine metabolic flux.

Nanoparticle impregnated self-supporting protein gel for enhanced reduction in oxidative stress: A molecular dynamics insight for lactoferrin-polyphenol interaction

In the present work, lactoferrin (Lf) based nanoparticle incorporated self-supporting gel encapsulating a flavonoid, quercetin (Q), was developed. The complex formation between Lf and Q was assessed using molecular docking and dynamics simulation that lactoferrin and quercetin showed strong interaction and binding supporting hydrophobic interaction. The microscopic, spectroscopic, and x-ray techniques were used to characterize the gel extensively. In vitro drug release was studied to understand the release pattern of quercetin from the protein gel. The viscosity of the gel and its rheological characteristics were determined using a Brookfield viscometer. Ex vivo skin permeation studies using vertical diffusion cells were carried out to understand its skin permeation properties. The gel showed strong anti-oxidant activity using the DPPH scavenging assay. The enhanced effect of the Lf-Q complex on antioxidant enzyme activity (superoxide dismutase, catalase, and malondialdehyde), was supported by molecular dynamics, surface hydrophobicity, and in vitro studies. To investigate the effect of the gel on angiogenesis, the chorioallantoic membrane assay was performed and its compatibility with erythrocytes was also assessed. Suitability for topical administration was assessed using skin irritation studies performed on Sprague Dawley rats. The overall results suggest that the developed NiPG is suitable for cutaneous localization of quercetin with enhanced antioxidant activity.

Nanoformulations of Ursolic Acid: A Modern Natural Anticancer Molecule

Background: Ursolic acid (UA) is a natural pentacyclic triterpene derived from fruit, herb, and other plants. UA can act on molecular targets of various signaling pathways, inhibit the growth of cancer cells, promote cycle stagnation, and induce apoptosis, thereby exerting anticancer activity. However, its poor water-solubility, low intestinal mucosal absorption, and low bioavailability restrict its clinical application. In order to overcome these deficiencies, nanotechnology, has been applied to the pharmacological study of UA.

Objective: In this review, we focused on the absorption, distribution, and elimination pharmacokinetics of UA in vivo, as well as on the research progress in various UA nanoformulations, in the hope of providing reference information for the research on the anticancer activity of UA.

Methods: Relevant research articles on Pubmed and Web of Science in recent years were searched selectively by using the keywords and subheadings, and were summarized systematically.

Key finding: The improvement of the antitumor ability of the UA nanoformulations is mainly due to the improvement of the bioavailability and the enhancement of the targeting ability of the UA molecules. UA nanoformulations can even be combined with computational imaging technology for monitoring or diagnosis.

Conclusion: Currently, a variety of UA nanoformulations, such as micelles, liposomes, and nanoparticles, which can increase the solubility and bioactivity of UA, while promoting the accumulation of UA in tumor tissues, have been prepared. Although the research of UA in the nanofield has made great progress, there is still a long way to go before the clinical application of UA nanoformulations.

Enzymatic and Nonenzymatic Conjugates of Lactoferrin and (-)-Epigallocatechin Gallate: Formation, Structure, Functionality, and Allergenicity

The impact of covalent attachment of (-)-epigallocatechin gallate (EGCG) to lactoferrin (LF) on the structure, morphology, functionality, and allergenicity of the protein was studied. These polyphenol-protein conjugates were formed using various enzymatic (laccase- and tyrosinase-catalyzed oxidation) and nonenzymatic (free radical grafting and alkali treatment) methods. The preparation conditions for forming the enzymatic conjugates were optimized by exploring the influence of order-of-addition effects: protein, polyphenols, and enzymes. The total phenol content of the LF-EGCG conjugates was quantified using the Folin-Ciocalteu method. The nature of the conjugates formed was determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared (FTIR) spectroscopy analyses. These studies showed that enzymatic cross-linking was a highly effective means of forming LF-EGCG conjugates. Analysis of these conjugates using various spectroscopic methods showed that conjugation to EGCG changed the molecular structure of LF. Atomic force microscopy showed that the four covalent cross-linking methods affected the size and morphology of these LF-EGCG conjugates formed. The antioxidant activity and emulsifying stability of LF were significantly improved by conjugation to EGCG. Finally, an enzyme-linked immunosorbent assay (ELISA) and a western blot assay indicated that conjugation of EGCG reduced the binding capacity of LF to immunoglobulin E (IgE) and immunoglobulin G (IgG), which is consistent with a decrease in allergenicity. Overall, this study suggests that LF-EGCG conjugates formed using enzymatic or nonenzymatic methods have potential applications as functional ingredients in foods.