Toxicogenomic evaluation of liver responses induced by acrylamide and glycidamide in male mouse liver.

In current studies, histopathologic method, Agilent GeneChip hybridization and Western blot were used to investigate the toxicity of acrylamide (AA) and glycidamide (GA) in male mouse livers. The histopathologic results demonstrated that AA and GA could cause oxidative damage to mouse liver. Middle dose of GA and AA (50 mg/kg b.w./day) could significantly up-regulate the expression of cytochrome P450, as well as genes related to oxidative injury, cancer and inflammation, and significantly down-regulate the expression of genes related to anti-apoptosis, antioncogene and fatty acid synthesis. Middle and high dose (75 mg/kg b.w./day) of GA and AA could both down-regulate the expression of hepatic anti-oncogene Bcl2 and up-regulate the expression of cancer-related gene Rad51 and EGFR protein. The expression of anti-oncogene P21 induced by AA and GA was decreased. Our current study demonstrated that the oxidative damage, immune injury and carcinogenicity of mouse liver samples could be induced by AA and GA at histopathological, entire genome and protein levels.

The Prebiotic Activity of Simulated Gastric and Intestinal Digesta of Polysaccharides from the Hericium erinaceus.

Hericium erinaceus (HE) is a well-known edible and medicinal fungus widely grown in Asian countries. Polysaccharides from the Hericium erinaceus (HEP) are major biological macromolecules. It has been reported that HEP has multiple biological activities, such as antioxidant activity, immunomodulatory effects, anti-inflammatory effect, anti-chronic gastritis activity, and so on. In the current study, we investigated the biological property of HEP during gastrointestinal digestion. The results indicated that both simulated gastric and small intestinal digesta of HEP has better stimulation of probiotics growth than HEP alone, especially for Lactobacillus plantarum BG112. The prebiotic activity was the strongest when HEP was treated by simulated gastric juice for 2 h and by simulated small intestinal juice for 4 h. The molecular weight (Mw) of HEP decreased from 1.68 × 106 Da and 2.32 × 104 Da to 529.3 ± 7.2 Da, as digestion time increased. Meanwhile, the reducing sugar content was significantly increased from 0.610 ± 0.007 to 22.698 ± 0.752 mg/ml, suggesting that the decrease of Mw was likely due to the breakdown of glycosidic bonds. Considerable mannose and galactopyranose were released throughout the gastrointestinal digestion period, indicating that the gastrointestinal digestion resulted in production of free monosaccharides. After fermentation of L. plantarum BG112, the Mw of HEP was decreased and short chain fatty acids (SCFAs) including acetic acid, isovaleric acid, lactic acid, and butyric acid were produced. We speculated that the release of free monosaccharides during gastrointestinal digestion and utilization of HEP, by the probiotics, contributed to the prebiotic activity of HEP's gastric and intestinal digesta. These results unveiled some mechanisms on the close relationship between the structure and bioactivity of polysaccharides, during digestion.

Antibacterial activity and mode of action of totarol against Staphylococcus aureus in carrot juice.

Food contaminated with pathogenic bacteria such as Staphylococcus aureus (S. aureus), represents a serious health risk to human beings. Totarol is an antibacterial novel phenolic diterpenes. In present study, the antibacterial activity of totarol against S. aureus was investigated in a food system. The antibacterial activity of totarol was determined by measuring the zones of inhibition and minimum inhibitory concentrations (MICs). The MICs for S. aureus strains were in the range of 2-4 µg/ml. The probable antibacterial mechanism of totarol was the alteration in cell membranes integrity and permeability, which leading to the leakage of cellular materials. The electric conductivity showed a time- and dose-dependent increasing manner, and we utilized totarol to induce the production of cytoplasmic ß-galactosidase in S. aureus. Scanning electron microscopy and transmission electron microscopy analysis further confirmed that S. aureus cell membranes were damaged by totarol. The time-kill assay and detection of the kinetics of S. aureus deactivation in situ indicated that totarol has good preservative activities in a food model. Totarol successfully inhibited S. aureus development in carrot juice, at room temperature (25 °C) and in refrigerator (4 °C) respectively. Our works provided not only additional evidences in support of totarol being regarded as a natural antibacterial food preservative but also fundamental understanding on the mode of antibacterial action. It is necessary to consider that totarol will become a promising antibacterial additive for food preservative.

In vitro antioxidant activities of the novel pentapeptides Ser-His-Glu-Cys-Asn and Leu-Pro-Phe-Ala-Met and the relationship between activity and peptide secondary structure.

BACKGROUND: Using high-performance liquid chromatography/tandem mass spectrometry, two novel antioxidant pentapeptides [Ser-His-Glu-Cys-Asn (SHECN) and Leu-Pro-Phe-Ala-Met (LPFAM)] were identified from 1-3-kDa soybean protein hydrolysates (SPH). The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay was used to evaluate cytotoxicity in HepG2 cells. Antioxidant activity was measured using in vitro assays, including the cellular antioxidant activity assay (CAA), 2,2-diphenyl-1-picrylhydrazyl or 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) inhibition, and oxygen radical absorbance capacity (ORAC) assays. Finally, the secondary structure was determined using circular dichroism (CD). RESULTS: The results revealed that two novel peptides were nontoxic and possessed antioxidant activity. SHECN had significantly higher antioxidant activity than LPFAM (P < 0.05). The CAA value of SHECN was 776.22 µmol QE 100 g-1 . SHECN also showed significant DPPH inhibition (70.18 ± 4.06%) and ABTS inhibition (88.16 ± 0.76%). It had normalized ORAC values of 0.3000 ± 0.0070 µmol GE mg-1 and 0.0900 ± 0.0020 µmol TE mg-1 , respectively. The results of the CD analysis demonstrated that, compared to LPFAM, which had much lower antioxidant activity, SHECN had a high ß-sheet content and reduced α-helix content. CONCLUSION: The results indicated that SHECN possessed high antioxidant activity. A higher ß-sheet content and lower content levels of α-helix appear to be correlated with antioxidant activity. © 2016 Society of Chemical Industry.

Marrow mesenchymal stromal cells reduce methicillin-resistant Staphylococcus aureus infection in rat models.

BACKGROUND AIMS: Staphylococci account for a large proportion of hospital-acquired infections, especially among patients with indwelling devices. These infections are often caused by biofilm-producing strains, which are difficult to eradicate and may eventually cause bacteremia and metastatic infections. Recent evidence suggests that mesenchymal stem cells can enhance bacterial clearance in vivo. METHODS: In this study, a rat model with carboxymethyl cellulose pouch infection was used to analyze the efficacy of bone marrow-derived mesenchymal stromal cells (BMSCs) against the methicillin-resistant Staphylococcus aureus. RESULTS: The results showed that the administration of BMSCs effectively reduced the number of bacterial colonies and the expression of many cytokines and chemokines (such as interleukin [IL]-6, IL-1ß, IL-10 and CCL5). Unlike the fibroblast control groups, the pouch tissues from the BMSC-treated rats showed the formation of granulations, suggesting that the healing of the wound was in progress. CONCLUSIONS: The results indicate that the treatment of BMSCs can reduce methicillin-resistant S aureus infection in vivo, thereby reducing the inflammatory response.

Preparation of sanguinarine/glabridin loaded antifungal double-layer nanoemulsion edible coating using arabic gum/WPI for forest frog's oviduct oil preservation.

Forest frog's oviduct oil (FFOO) is highly susceptible to microbial spoilage during storage, which causes serious safety concerns and economic losses. However, little information is available regarding the preservation of it up to now. The aim of this research is to understand the dominant microbial community of FFOO spoilage, and based on this, develop a kind of edible nanoemulsion coating for preserving FFOO. Microbial metagenomic analysis indicated that the Aspergillus genus increased significantly during storage. In the present study, gum arabic and whey protein isolate were chosen as the coating matrix, the natural compounds sanguinarine and glabridin were selected as antimicrobial agents to prepare double-layer nanoemulsion edible coating. When the ratio of sanguinarine and glabridin in the nanoemulsion was 1:3, it exhibited strongest storage stability and antifungal activity. The mycelial inhibition rate of 1:3 nanoemulsion against dominant microbial community (Aspergillus niger and Aspergillus glaucus) reached 88.89 ± 1.37 % and 89.68 ± 1.37 %, respectively. The experimental results indicated that the edible nanoemulsion coating not only had outstanding antifungal activity, but also had excellent fresh-keeping effect on FFOO. This nanoemulsion coating could be a promising and potential candidate for food preservation.

Zearalenone removal using inactivated yeast embedded in porous modified yam starch aerogels and its application in corn silk tea.

Zearalenone contaminates food and poses a threat to human health. It is vital to develop cost-effective and environmentally-friendly adsorbents for its removal. By screening Sporobolomyces pararoseus (SZ4) and modified yam starch (adsorption capacity (qe) of 1.33 and 0.94 mg/g, respectively), this study prepared a novel composite aerogel adsorbent (P-YSA@SZ410). The compressive strength of P-YSA@SZ410 was 1.35-fold higher than unloaded yeast. It contained several functional groups and three-dimensional interconnected channels, achieving a 0° contact angle within 0.18 s, thereby demonstrating excellent water-absorbent properties. With a qe of 2.96 mg/g at 308 K, the adsorption process of P-YSA@SZ410 was spontaneous, endothermic, and matched pseudo-second-order and Langmuir models. The composite adsorbed zearalenone via electrostatic attraction and hydrogen bonding, maintaining a qe of 2.24 mg/g after five cycles. P-YSA@SZ410 was found to remove zearalenone effectively under various conditions and could be applied to corn silk tea, indicating its great potential as an adsorbent material.

Transformation of mulberry polyphenols by Lactobacillus plantarum SC-5: Increasing phenolic acids and enhancement of anti-aging effect.

Fermentation can transform bioactive compounds in food and improve their biological activity. This study aims to explore the transformation of polyphenols in mulberry juice and the improvement of its anti-aging effect. The results demonstrated that Lactobacillus plantarum SC-5 transformed anthocyanin in mulberry juice into more phenolic acids, especially improved 2-hydroxy-3-(4-hydroxyphenyl) propanoic acid from 4.16 ± 0.06 to 10.07 ± 0.03. In the D-gal-induced mouse model, fermented mulberry juice significantly raised the abundance of Bifidobacteriaceae (303.7 %) and Lactobacillaceae (237.2 %) and Short-chain fatty acids (SCFAs) in intestine, further reducing the level of oxidative stress (12.3 %). Meanwhile, the expression of Sirtuin 1 (SIRT1) and Brain-derived neurotrophic factor (BDNF) increased, which protected the integrity of hippocampal tissue. Morris water maze results approved that fermented mulberry juice improved cognitive ability in aging mice (30.3 %). This study provides theoretical support for the view that fermentation is an effective means of developing functional foods.

Dietary regulation of peroxisome proliferator-activated receptors in metabolic syndrome.

BACKGROUND: Peroxisome proliferator-activated receptors (PPARs) are a class of ligand-activated nuclear transcription factors, members of the type nuclear receptor superfamily, with three subtypes, namely PPARα, PPARß/δ, and PPARγ, which play a key role in the metabolic syndrome. In the past decades, a large number of studies have shown that natural products can act by regulating metabolic pathways mediated by PPARs. PURPOSE: This work summarizes the physiological importance and clinical significance of PPARs and reviews the experimental evidence that natural products mediate metabolic syndrome via PPARs. METHODS: This study reviews relevant literature on clinical trials, epidemiology, animals, and cell cultures published in NCBI PubMed, Scopus, Web of Science, Google Scholar, and other databases from 2001 to October 2022. Search keywords were "natural product" OR "botanical" OR "phytochemical" AND "PPAR" as well as free text words. RESULTS: The modulatory involvement of PPARs in the metabolic syndrome has been supported by prior research. It has been observed that many natural products can treat metabolic syndrome by altering PPARs. The majority of currently described natural compounds are mild PPAR-selective agonists with therapeutic effects that are equivalent to synthetic medicines but less harmful adverse effects. CONCLUSION: PPAR agonists can be combined with natural products to treat and prevent metabolic syndrome. Further human investigations are required because it is unknown how natural products cause harm and how they might have negative impacts.

Insights into the Mechanisms of Reuterin against Staphylococcus aureus Based on Membrane Damage and Untargeted Metabolomics.

Reuterin is a dynamic small-molecule complex produced through glycerol fermentation by Limosilactobacillus reuteri and has potential as a food biopreservative. Despite its broad-spectrum antimicrobial activity, the underlying mechanism of action of reuterin is still elusive. The present paper aimed to explore the antibacterial mechanism of reuterin and its effects on membrane damage and the intracellular metabolome of S. aureus. Our results showed that reuterin has a minimum inhibitory concentration of 18.25 mM against S. aureus, based on the 3-hydroxypropionaldehyde level. Key indicators such as extracellular electrical conductivity, membrane potential and permeability were significantly increased, while intracellular pH, ATP and DNA were markedly decreased, implying that reuterin causes a disruption to the structure of the cell membrane. The morphological damage to the cells was confirmed by scanning electron microscopy. Subsequent metabolomic analysis identified significant alterations in metabolites primarily involved in lipid, amino acid, carbohydrate metabolism and phosphotransferase system, which is crucial for cell membrane regulation and energy supply. Consequently, these findings indicated that the antibacterial mechanism of reuterin initially targets lipid and amino acid metabolism, leading to cell membrane damage, which subsequently results in energy metabolism disorder and, ultimately, cell death. This paper offers innovative perspectives on the antibacterial mechanism of reuterin, contributing to its potential application as a food preservative.

Recent advances in nuclear receptors-mediated health benefits of blueberry.

BACKGROUND: Blueberry is rich in bioactive substances and has anti-oxidant, anti-inflammatory, anti-obesity, anti-cancer, neuroprotective, and other activities. Blueberry has been shown to treat diseases by mediating the transcription of nuclear receptors. However, evidence for nuclear receptor-mediated health benefits of blueberry has not been systematically reviewed. PURPOSE: This review aims to summarize the nuclear receptor-mediated health benefits of blueberry. METHODS: This study reviews all relevant literature published in NCBI PubMed, Scopus, Web of Science, and Google Scholar by January 2022. The relevant literature was extracted from the databases with the following keyword combinations: "biological activities" OR "nuclear receptors" OR "phytochemicals" AND "blueberry" OR "Vaccinium corymbosum" as well as free-text words. RESULTS: In vivo and in vitro experimental results and clinical evidence have demonstrated that blueberry has health-promoting effects. Supplementing blueberry is beneficial to the treatment of cancer, the alleviation of metabolic syndrome, and liver protection. Blueberry can regulate the transcription of PPARs, ERs, AR, GR, MR, LXRs, and FXR and mediate the expressions of Akt, CYP 1Al, p53, and Bcl-2. CONCLUSION: Blueberry can be targeted to treat various diseases by mediating the transcription of nuclear receptors. Nevertheless, further human research is needed.

Water distribution and moisture-absorption in egg-white derived peptides: Effects on their physicochemical, conformational, thermostable, and self-assembled properties.

Three egg-white derived peptides (DHTKE, MPDAHL, and FFGFN) were characterized with hydrophilia and water distributions. The effect of moisture exposure on their properties at 75% relative humidity for 30 h were further investigated. LF-NMR tests revealed that strong bound-water (relaxation time < 10 ms) accounted for more than 80% of total water in peptides after moisture-absorption. The absorbed water led to the pH of three peptides increase, antioxidant activities in vitro decrease, and diverse changes in their functional group vibrations, molecular hydrophobicity, and phase transformation properties. Compared to dried samples, the hydrated-DHTKE was pyrolyzed and hydrated-MPDAHL was oxidized over 160 °C, while the glass transition, melting, and crosslink temperatures of FFGFN all decreased after moisture-absorption. Moreover, the results indicated that moisture-absorption in FFGFN powder enhanced the surface-hydrophobicity of FFGFN-hydrogel and accelerated its self-organizations. This study provides a comprehensive understanding of moisture-absorption effects on peptides, with these changes potentially impacting storage recommendations and scientific interpretations.

Glycated modification of the protein from Rana chensinensis eggs by Millard reaction and its stability analysis in curcumin encapsulated emulsion system.

Forest frog (Rana chensinensis) eggs contain high-quality protein but have not been well utilized. In this study, the total protein of forest frog eggs was extracted and 4491 protein/peptides were identified by HPLC-MS/MS. The egg protein was glycated using monosaccharides (lactose, fructose, xylose and glucose). The xylose modified egg protein showed excellent emulsifying ability, high viscosity and uniform structure under the laser confocal microscope in a concentration dependent way (1-3%, w/v). We next used xylose glycated egg protein to encapsulate curcumin to determine the stability of its emulsion system. This emulsion system showed low particle size (< 400 nm) and high Zeta-potential (> 30 mV with absolute value) at pH > 6. The system was stable under 4 °C, 25℃ and 37 °C after seven weeks' storage, especially for the emulsions at 3% and 5% concentrations. Therefore, the glycated frog egg protein can be used to encapsulate hydrophobic nutrients.

Probiotic Properties of a Spaceflight-induced Mutant Lactobacillus Plant- arum SS18-50 in Mice.

BACKGROUND: Probiotics are a group of bacteria that play a critical role in intestinal microbiota homeostasis and may help adjunctively treat certain diseases like metabolic and immune disorders. OBJECTIVE: We recently generated a space-flight mutated Lactobacillus plantarum SS18-50 with good in vitro probiotic characteristics. In the current research, we designed two in vivo experiments to evaluate whether L. plantarum SS18-50 had the ability to increase beneficial gut bacteria, regulate oxidative status and ameliorate inflammation in mice. METHODS: Experiments I: the ICR mice were gavaged with L. plantarum SS18-50 or its wild type L. plantarum GS18 at 107 or 109 CFU/kg BW daily for one month, during which the body weight was recorded weekly. The feces were collected to determine the abundance of two main beneficial bacterial groups including Lactobacillus and Bifidobacterium by selective culturing, while the total triglycerides and cholesterols in sera were determined using commercial kits. Experiment II: the mice were gavaged with loperamide hydrochloride (Lop) to develop oxidative stress and inflammation phenotypes. At the same time, the experimental mice were gavaged with L. plantarum SS18-50 or wild type L. plantarum GS18 at 107 or 109 CFU/kg BW daily for one month. At the end of the experiment, oxidative indicators (SOD and MDA) and inflammatory cytokines (IL-17A and IL-10) were measured by commercial kits. RESULTS: Results showed that L. plantarum SS18-50 increased the abundance of Lactobacillus and Bifidobacterium in mice after one month's administration. L. plantarum SS18-50 also showed the anti-oxidant activity by increasing SOD and decreasing MDA and exerted the anti-inflammatory effect by increasing IL-10 and decreasing IL-17A in Lop treated mice. Both the wild type stain and the space mutant had such biomedical effects, but L. plantarum SS18-50 was better in increasing gut beneficial bacteria and oxidative regulation than the wild type (P<0.05). CONCLUSION: We conclude that L. plantarum SS18-50 has a great potential to serve as a dietary functional probiotic supplement and/or adjunctive treatment strategy.

Lack of toxicological effect through mutagenicity test of polyphenol extracts from peanut shells.

The toxicological effect of polyphenols extracted from peanut shells was investigated in animal models. The safety data were needed to proceed with further clinical trials. The oral LD50 of peanut shells polyphenols was determined to be higher than 15,000mg/kg body weight. We also carried out a sperm abnormality test, a chromosomal aberration test and a micronucleus test in rats. The peanut shell polyphenols did not cause any abnormalities in the system. Furthermore, the administration of peanut shell polyphenols did not significantly alter changes in body weight or clinical signs. These results strongly indicated that peanut shell polyphenols did not induce mutagenicity. The results of this study suggested a lack of toxicological effect and supported the further use of polyphenol-rich extracts from peanut shells as a potential natural antioxidant.

Effect of microorganisms on the fingerprint of the volatile compounds in pine nut (Pinus koraiensis) peptide powder during storage.

Pine nut (Pinus koraiensis) peptide (PNP) powder possesses promising bioactivities. However, the powder may have the quality problem of becoming sticky and smelly. Therefore, the volatile compounds' fingerprint of PNP powder was established by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). The essential spoilage microorganisms were confirmed by 16S rDNA amplicon sequencing. The antioxidant activity, which presents PNP powder's quality, decreased during storage with the highest value of (1.88 ± 0.18) × 1014 at day 30. Fifty-nine significantly changed signals were detected; eight compounds were considered as volatile marker compounds. Besides, Firmicutes and Cyanobacteria were the essential spoilage microorganisms in PNP powder at the phylum level. Significantly, unidentified_Chloroplast, which belongs to Cyanobacteria, had a positive correlation with volatile marker compounds. The results proved that microorganisms indeed affect volatile compounds of PNP powder and induced off-flavor, including hexanal, which can be used as the detection indicator for the quality control of PNP powder. PRACTICAL APPLICATIONS: In the present study, we controlled the influence of moisture migration on PNP powder and investigated microorganisms' effects on volatile compounds of PNP powder. HS-GC-IMS could be used to establish fingerprints of volatile compounds in PNP powder. 16S rDNA amplicon sequencing method could be used to screen the dominant spoilage bacteria in PNP powder and established essential spoilage microorganisms of PNP powder. This work provides a reference for category identification of PNP powder, which was infected by spoilage bacteria or not, and stored at day 0 or 30 days. Hexanal can be considered as the volatile marker compound generated from microorganisms. It helps to realize the controllability of PNP powder storage and prolongs the shelf life of PNP powder.

A review on pharmacological activities and synergistic effect of quercetin with small molecule agents.

BACKGROUND: Quercetin is a natural flavonoid, which widely exists in nature, such as tea, coffee, apples, and onions. Numerous studies have showed that quercetin has multiple biological activities such as anti-oxidation, anti-inflammatory, and anti-aging. Hence, quercetin has a significant therapeutic effect on cancers, obesity, diabetes, and other diseases. In the past decades, a large number of studies have shown that quercetin combined with other agents can significantly improve the overall therapeutic effect, compared to single use. PURPOSE: This work reviews the pharmacological activities of quercetin and its derivatives. In addition, this work also summarizes both in vivo and in vitro experimental evidence for the synergistic effect of quercetin against cancers and metabolic diseases. METHODS: An extensive systematic search for pharmacological activities and synergistic effect of quercetin was performed considering all the relevant literatures published until August 2021 through the databases including NCBI PubMed, Scopus, Web of Science, and Google Scholar. The relevant literatures were extracted from the databases with following keyword combinations: "pharmacological activities" OR "biological activities" OR "synergistic effect" OR "combined" OR "combination" AND "quercetin" as well as free-text words. RESULTS: Quercetin and its derivatives possess multiple pharmacological activities including anti-cancer, anti-oxidant, anti-inflammatory, anti-cardiovascular, anti-aging, and neuroprotective activities. In addition, the synergistic effect of quercetin with small molecule agents against cancers and metabolic diseases has also been confirmed. CONCLUSION: Quercetin cooperates with agents to improve the therapeutic effect by regulating signal molecules and blocking cell cycle. Synergistic therapy can reduce the dose of agents and avoid the possible toxic and side effects in the treatment process. Although quercetin treatment has some potential side effects, it is safe under the expected use conditions. Hence, quercetin has application value and potential strength as a clinical drug. Furthermore, quercetin, as the main effective therapeutic ingredient in traditional Chinese medicine, may effectively treat and prevent coronavirus disease 2019 (COVID-19).

Lactoferrin-thymol complex for the disinfection of gram-positive Staphylococcus aureus and Gram-negative Escherichia coli.

Seeking all-nature derived antibacterial agents with effective disinfection function, high human safety as well as environment-friendly characteristics are highly required in the food industry. Herein, we report the lactoferrin-thymol (LF-Thy) complex as an effective killing agent against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). The multi-spectroscopy results clearly demonstrate the combination of LF and Thy to form the LF-Thy complex, accompanied with LF conformation variations including the increase in the hydrophobicity of amino acid residues and changes in the types of secondary conformation distribution in LF. Molecular docking results show that LF exhibits three possible binding sites and five predicted stable binding modes for Thy with the help of hydrogen bonding and hydrophobic interactions. Moreover, LF-Thy demonstrated a significantly higher antibacterial ability compared to LF and displays effective disinfection function against E. coli and S. aureus. The minimum inhibitory concentration (MIC) of LF toward E. coli and S. aureus is >40 mg mL-1 and 40 mg mL-1, which decreases to 10 mg mL-1 and 5 mg mL-1 after combination with Thy, respectively. This work demonstrates the promising antibacterial activities of the LF-Thy complex and provides an alternative agent for combating bacterial infection in the food industry, which holds great potential for promoting the development of the all-natural healthcare food complex.

Effect of ultrasound pretreatment on structural, physicochemical, rheological and gelation properties of transglutaminase cross-linked whey protein soluble aggregates.

A solution (10%, w/v) of whey protein soluble aggregates (WPISA) was pretreated with high-intensity ultrasound (HUS, 20 kHz) for different durations (10-40 min) before incubation with transglutaminase (TGase) to investigate the effect of HUS on the structural, physicochemical, rheological, and gelation properties of TGase cross-linked WPISA. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results showed that HUS increased the amounts of high-molecular-weight polymers/aggregates in WPISA after incubation with TGase. HUS significantly increased (P < 0.05) the degree of TGase-mediated cross-linking in WPISA, as demonstrated by a reduction in free amino group contents. HUS significantly increased (P < 0.05) the particle size, intrinsic fluorescence intensity, and surface hydrophobicity of TGase cross-linked WPISA, but had no significant impact (P > 0.05) on the zeta-potential or total free sulfhydryl group content of TGase cross-linked WPISA. The apparent viscosity and the consistency index of TGase cross-linked WPISA were significantly increased by HUS (P < 0.05), which indicated that HUS facilitated the formation of more high-molecular-weight polymers. HUS significantly increased (P < 0.05) the water holding capacity and gel strength of glucono-δ-lactone (GDL)-induced TGase cross-linked WPISA gels. The results indicated that HUS could be an efficient tool for modifying WPISA to improve its degree of TGase-mediated cross-linking, which would lead to improved rheological and gelation properties.

Spectroscopic and in silico investigation of the interaction between GH1 ß-glucosidase and ginsenoside Rb1.

The function and application of ß-glucosidase attract attention nowadays. ß-glucosidase was confirmed of transforming ginsenoside Rb1 to rare ginsenoside, but the interaction mechanism remains not clear. In this work, ß-glucosidase from GH1 family of Paenibacillus polymyxa was selected, and its gene sequence bglB was synthesized by codon. Then, recombinant plasmid was transferred into Escherichia coli BL21 (DE3) and expressed. The UV-visible spectrum showed that ginsenoside Rb1 decreased the polarity of the corresponding structure of hydrophobic aromatic amino acids (Trp) in ß-glucosidase and increased new π-π* transition. The fluorescence quenching spectrum showed that ginsenoside Rb1 inhibited intrinsic fluorescence, formed static quenching, reduced the surface hydrophobicity of ß-glucosidase, and KSV was 8.37 × 103 L/M (298K). Circular dichroism (CD) showed that secondary structure of ß-glucosidase was changed by the binding action. Localized surface plasmon resonance (LSPR) showed that ß-glucosidase and Rb1 had strong binding power which KD value was 5.24 × 10-4 (±2.35 × 10-5) M. Molecular docking simulation evaluated the binding site, hydrophobic force, hydrogen bond, and key amino acids of ß-glucosidase with ginsenoside Rb1 in the process. Thus, this work could provide basic mechanisms of the binding and interaction between ß-glucosidase and ginsenoside Rb1.