Exploring plant polyphenols as anti-allergic functional products to manage the growing incidence of food allergy.

The active substances derived from plants have received increasing attention owing to their wide range of pharmacological applications, including anti-tumor, anti-allergic, anti-viral, and anti-oxidative activities. The allergy epidemic is a growing global public health problem that threatens human health and safety. Polyphenols from plants have significant anti-allergic effects and are an important source of anti-allergic drug research and development. Here, we describe recent advances in the anti-allergic efficacy of plant polyphenols, including their comprehensive effects on cellular or animal models. The current issues and directions for future development in this field are discussed to provide a theoretical basis for the development and utilization of these active substances as anti-allergic products.

A novel antioxidant protein of non-phycobiliprotein family derived from marine red alga Porphyra haitanensis.

BACKGROUND: Oxidation has been reported as the one of the deterioration reactions of proteins in aquatic products. Searching for new bioactive substances from marine algae has been one of the main areas in food science and additives. RESULTS: In this study, a novel protein from the red alga Porphyra haitanensis was determined after ammonium sulfate precipitation and gel filtration chromatography. It closely corresponded to the antioxidant activity and was identified as an uncharacterized protein with a molecular mass of 43 kDa, designated Ph43. Bioinformatic analysis revealed that Ph43 is a novel protein of non-phycobiliprotein family with putative chordin domains and rich in α-helical conformation. Recombinant protein (rPh43) was expressed in Escherichia coli as a Hig-tagged protein using a pET-22b vector system and purified by affinity high-performance liquid chromatography. Spectroscopy analysis revealed that there were no structural differences between rPh43 and natural recovered Ph43. Moreover, rPh43 showed equal/higher antioxidant activity compared with Ph43. rPh43 has the potential for application as a natural antioxidant for food stabilization. CONCLUSION: Our results identified a novel antioxidant protein with molecular mass of 43 kDa derived from Porphyra haitanensis that belongs to the non-phycobiliprotein family. © 2023 Society of Chemical Industry.

Isolation and characterization of antioxidant peptides from oyster (Crassostrea rivularis) protein enzymatic hydrolysates.

Peptides from oysters have several bioactive functions. In this study, we identified antioxidant peptides from oysters (Crassostrea rivularis) and investigated their structure-function relationship. We used an 8 kDa molecular-weight (MW) cut-off membrane and semiprep reversed-phase liquid chromatography to collect five peptides (F1-F5) and identified the highest-abundance ion-peak sequences AWVDY (F1), MSFRFY(F2), EPLRY(F3), RKPPWPP(F4), and YAKRCFR(F5) having MWs of 652, 850, 676, 877, and 943 Da, respectively, using ultra-performance liquid chromatography-quadrupole/time-of-flight tandem mass spectrometry. These peptides exhibited high antioxidant activities, similar to butylated hydroxytoluene, reduced glutathione, and ascorbic acid. F5 demonstrated the highest scavenging activity for DPPH radicals (IC50 = 21.75 µg/ml), hydroxyl radicals (IC50 = 18.75 µg/ml), and superoxide radicals (IC50 = 11.00 µg/ml), while F3 demonstrated the highest reducing power. Furthermore, F5 significantly protected Caco-2 cells from H2O2-induced oxidative damage. These results suggest that the antioxidant peptide F5 is a promising food additive that protects against oxidative damage.

Antioxidant Activity of Gracilaria lemaneiformis Polysaccharide Degradation Based on Nrf-2/Keap-1 Signaling Pathway in HepG2 Cells with Oxidative Stress Induced by H2O2.

The objective of this research was to investigate the antioxidant activity of Gracilarialemaneiformis polysaccharide degradation and its underlying mechanism involved in the Nrf-2/Keap-1 signaling pathway in HepG2 cells with oxidative stress induced by H2O2. The result of the scavenging ability of free radicals showed that GLP-HV (polysaccharide degraded by H2O2-vitamin C (Vc)) performed a better scavenging ability than GLP (G.lemaneiformis polysaccharide). Moreover, the scavenging ability of polysaccharide to these free radicals from strong to weak was as follows: superoxide radical, ferric ion, ABTS+, and DPPH radical, and their IC50 values were 3.56 ± 0.0028, 4.97 ± 0.18, 9.62 ± 0.35, and 23.85 ± 1.78 mg/mL, respectively. Furthermore, GLP-HV obviously relieved oxidative stress in HepG2 cells, which strengthened the activity of T-AOC, CAT, GSH-PX, and SOD, and diminished the intensity of MDA, intracellular ROS, and calcium ion based on the Nrf-2/Keap-1 signaling pathway. The PCR result revealed that polysaccharide upregulated the expression of the genes Nrf-2, HO-1, NQO-1, and ZO-1 and downregulated Keap-1. The correlation between chemical properties and antioxidant mechanism of GLP-HV was evaluated via a heat map. The results illustrated that reducing sugar and active groups presented a positive correlation, and molecular weight and viscosity exhibited a negative relation with antioxidant activity.

Preparation, purification, and identification of novel antioxidant peptides derived from Gracilariopsis lemaneiformis protein hydrolysates.

Gracilariopsis lemaneiformis (G. lemaneiformis) protein was hydrolyzed with alkaline protease to obtain antioxidant peptides. The enzymatic hydrolysis conditions were optimized through single-factor and orthogonal experiments. The results showed that the optimal process parameters were using 2% of alkaline protease, and substrate concentration of 1 g/100 mL and hydrolyzed 2 h at pH 8.0. Gel filtration chromatography and RP-HPLC were adopted for isolating and purifying the antioxidant peptides from the G. lemaneiformis protein hydrolysate (GLPH). Three novel antioxidant peptides were identified as LSPGEL (614.68 Da), VYFDR (698.76 Da), and PGPTY (533.57 Da) by nano-HPLC-MS/MS. The results of ABTS free radical scavenging rate demonstrated PGPTY exhibited the best antioxidant activity (IC50 = 0.24 mg/mL). Moreover, LSPGEL, VYFDR, and PGPTY were docked with Keap1, respectively. The molecular docking results suggested PGPTY had smaller docking energy and inhibition constants than the other two peptides. Finally, the cell viability assay evidenced the protective effect exerted by the antioxidant peptide on H2O2-induced oxidative damage. Above findings showed the potential of using antioxidant peptides from GLPH as antioxidants.

Insights on preparation, structure and activities of Gracilaria lemaneiformis polysaccharide.

Gracilaria lemaneiformis is a kind of edible economic red algae, which is rich in polysaccharide, phycobiliprotein, pigments, minerals and other nutrients and functional components. Polysaccharide is one of the main active components of Gracilaria lemaneiformis, which has been reported to present various physiological bioactivities, including regulation of glycolipid metabolism, immune, anti-tumor, anti-inflammatory and other biological activities. This paper aims to provide a brief summary of extraction, purification, structural characteristics, and physiological activities of Gracilaria lemaneiformis polysaccharide (GLP). This article is able to provide theoretical basis for the future research and exploitation of GLP, and improve its potential development to promote the healthy and sustainable processing and high value utilization industry of Gracilaria lemaneiformis.

Purification and identification of antioxidant peptides from round scad (Decapterus maruadsi) hydrolysates by consecutive chromatography and electrospray ionization-mass spectrometry.

Round scad (Decapterus maruadsi) was hydrolyzed with a double-enzyme (a mixture of neutrase and trypsin) to obtain antioxidant peptides. The round scad hydrolysates obtained by 5-h hydrolysis (RSH) displayed the strongest antioxidant activities, which could scavenge the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, the hydroxyl radical, and exhibit reducing power. RSH was further separated into four fractions by using an ultrafiltration membrane system, and low-molecular-weight fraction RSH-IV (<5 kDa) showed the highest antioxidant activities. Fraction RSH-IV was then purified with gel filtration chromatography followed by reverse high-performance liquid chromatography (RP-HPLC). The sequence of the purified antioxidant peptide was identified as Lys-Gly-Phe-Arg (506 Da) by liquid chromatography/electrospray ionization tandem mass spectrometry (LC-MS/MS). Additionally, the purified peptide could scavenge DPPH radical at IC50 value of 0.13 mg/mL, and it showed a 49.08-fold higher DPPH radical scavenging activity compared with that of the crude RSH. The results suggest that antioxidant peptides obtained from round scad (Decapterus maruadsi) could be a good source of natural antioxidant.

Purification and Identification of Antioxidant Peptides from Schizochytrium Limacinum Hydrolysates by Consecutive Chromatography and Electrospray Ionization-Mass Spectrometry.

Schizochytrium limacinum residue was hydrolyzed with various proteases (papain, trypsin, Flavourzyme, Protamex, and Alcalase 2.4L) to obtain antioxidative peptides. The results showed that the S. limacinum hydrolysates (SLHs) prepared with compound proteases (Protamex and Alcalase 2.4L) had the highest antioxidant activity, which was measured using methods such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability (IC50 = 1.28 mg/mL), hydroxyl radical scavenging ability (IC50 = 1.66 mg/mL), and reducing power (1.42 at 5.0 mg/mL). The hydrolysates were isolated and purified by ultrafiltration, gel filtration chromatography, and reverse-phase high-performance liquid chromatography (RP-HPLC). Through analysis of electrospray ionization-mass spectrometer (ESI-MS/MS), the purified antioxidant peptide was identified as Pro-Tyr-Lys (406 Da). Finally, the identified peptide was synthesized for evaluating its antioxidant activity. The •OH scavenging ability and reducing power of Pro-Tyr-Lys were comparable to those of reduced L-glutathione (GSH). These results demonstrated that the antioxidant peptides from SLHs could potentially be used as effective antioxidants.

Acid stress induces cross-protection for cadmium tolerance of multi-stress-tolerant Pichia kudriavzevii by regulating cadmium transport and antioxidant defense system.

The toxicity of cadmium (Cd) is the major limitation to its removal using microorganisms. The Cd tolerance of Pichia kudriavzevii was obviously enhanced by acid stress based on multi-stress cross-protection. RNA-Seq showed that most differentially expressed genes (DEGs) in the Pentose phosphate pathway, Citrate cycle (TCA cycle), Glycolysis/Gluconeogenesis, Peroxisome and Glutathione metabolism were up-regulated by acid stress. The up-regulated expression of genes related to ATP synthesis (GOR1, ALD5, ADH4, ADH6, MDH2, IDH1, IDH2, and ATP19) and Cd transport (GSTY2, GTO2, GLO2, and YOR1), and the improvement of intracellular GSH level and GST activity, reduced the Cd toxicity towards P. kudriavzevii. Cd efflux by YOR1 played a key role in the decline of intracellular Cd level. Acid stress obviously improved the gene expression levels and activities of antioxidant enzymes (SOD, POD, and CAT), which inhibited the Cd-induced ROS outburst and oxidative damage of proteins and membrane lipids. In addition, the enhanced expression of HSP12 protected P. kudriavzevii from the damage of Cd stress. These results provide some important clues to reconstruct robust strains using for Cd removal in aquatic environments.

Molecular modification, expression and purification of new subtype antioxidant peptide from Pinctada fucata by recombinant Escherichia coli to improve antioxidant-activity.

The aim of this study was to establish a system for the efficient expression and purification of new subtype of antioxidant peptide from Pinctada fucata meat (NPFMAP), which is designed by molecular modification technology based on the sequence of purified and identified antioxidant peptide from Pinctada fucata meat (PFMAP, Gly-Ala-Gly-Leu-Pro-Gly-Lys-Arg-Glu-Arg), and to better understand the relationship between structure and antioxidant activity. Meanwhile, gene codon usage was optimized and the glutathione S-transferase (GST) tag of pGEX-6P-1 was added to facilitate expression and purification NPFMAP in Escherichia coli. The results of antioxidant activity assay in vitro showed a higher antioxidant activity in NPFMAP than that in enzymatic hydrolysis digested or chemically synthesized PFMAP. In particular, the DPPH scavenging radical activity increased by about 4.7 times after molecular modification. Structural bioanalysis indicated that new subtype antioxidant peptide had spatial conformation and good hydrophilic after modification, which was confirmed by antioxidant activity assays. Thus, the proposed method could be used to obtain NPFMAP with high antioxidant activity.

Cadmium detoxification induced by salt stress improves cadmium tolerance of multi-stress-tolerant Pichia kudriavzevii.

Heavy metal tolerance of microorganisms is the basis of heavy metal removal by growing cells. In this study, a cross-protection effect generated by salt stress significantly enhanced the cadmium tolerance of multi-stress-tolerant Pichia kudriavzevii. Comparative transcriptome analysis using RNA-Seq linked with physiological and biochemical observation was used to elucidate the underlying mechanisms of the improved cadmium tolerance. The expression of cadmium transport related genes (GSTY2, GLR1, GLO2, YCF1 and YOR1), GSH content and GST activity were elevated by salt stress, suggesting enhanced cadmium conjugation and detoxification in yeast cells. The inhibited cadmium uptake by ZRT1 and enhanced cadmium efflux by YOR1 contributed to the decrease in the intracellular cadmium concentration. The improved expression of antioxidant enzyme genes (SOD1, SOD2, SOD6, CAT1 and PRXIID), along with the enhanced activities of antioxidant enzymes (SOD, CAT and POD) resulted in a decrease in cadmium-induced ROS production, protein carbonylation, lipid peroxidation and cell death. The abundant expression of heat shock protein genes (HSP12, HSP10 and SSC1) and genes related to trehalose synthesis (TPS1 and TSL1) induced by salt stress protected yeast cells against complex stress conditions, contributing to the improved cadmium tolerance. These findings will be useful to develop cadmium-tolerant yeasts for cadmium removal by growing cells.

The effects of different extraction methods on composition and storage stability of sturgeon oil.

The objective of this study was to assess the effect of different extraction methods on oil yield, colour attributes, oxidative stability, fatty acids composition and production of volatile compounds in sturgeon oil during storage. The supercritical fluid extraction (SFE) method with carbon dioxide resulted in higher oil yields, better colour attributes, and higher oxidative stability compared to other traditional extraction methods such as enzymatic extraction, amino, and wet reduction. After storage at 4 °C for 33 days, the aldehyde content in oil extracted by the enzymatic extraction and wet reduction methods was twice as high as that obtained by the other methods. There was a significant reduction in the content of total acids in oils extracted by the enzymatic extraction and wet reduction methods (p<0.05), whereas amine compounds were mainly detected in oil extracted by the amino method. The oil extracted by SFE exhibited higher UFA and lower SFA. Significant diffidence among PUFA with C above 20 was observed in oil extracted with SFE.

Influence of emulsion composition and spray-drying conditions on microencapsulation of tilapia oil.

The influence of processing conditions on the microencapsulation of tilapia oil by spray drying was studied. Trehalose, gelatin, sucrose and xanthan were used as emulsion composition. The experimental parameters of spray drying such as inlet air temperature, solid content, drying air flow rate and atomizing pressure were optimized using a central composite design. Encapsulation efficiency and lipid oxidation were determined. Bulk density, powder morphology and particle size were also analyzed. Trehalose improved the glass transition temperature of wall material significantly and prevented the oxidation of the fish oil. Encapsulation efficiency reached a maximum of 90 % under optimum conditions with an inlet air temperature of 121 °C, a drying air flow rate of 0.65 m(3)/min and a spray pressure of 100 kPa.

Detection of white matter lesions in the acute stage of diffuse axonal injury predicts long-term cognitive impairments: a clinical diffusion tensor imaging study.

BACKGROUND: White matter disruption is known to contribute to neurocognitive deficits after diffuse axonal injury (DAI). This study evaluated the relationship between white matter integrity using diffusion tensor imaging in the early stage and cognitions in the chronic stage. METHODS: Diffusion tensor imaging was performed in 15 patients with DAI within 7 days of injury and in 15 patients in the control group. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were calculated within regions of interest, including the posterior limb of the internal capsule, uncinate fasciculus (UF), anterior corona radiate (ACR), superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus (ILF), genu of the corpus callosum, body of the corpus callosum, and splenium of the corpus callosum and cingulum bundle (CB). The patients with DAI and the patients in the control group also underwent neuropsychological testing during the chronic stage after DAI. RESULTS: The region-of-interest analysis showed significantly reduced FA and AD values in all nine regions within 7 days of injury as well as increased MD values in the corpus callosum among patients in the DAI group. The patients demonstrated significantly poorer performance on the working memory tests and attention test. In patients, working memory function was positively correlated with the AD value in the UF and with the FA value in the CB, UF, SLF, and ILF. Working memory function was inversely correlated with the RD value in the CB, SLF, and ILF and with the MD value in the SLF and ILF. In addition, the attention function demonstrated a positive correlation with the RD value in the ACR, SLF, and ILF and with the MD value in the ACR, SLF, and ILF. In addition, attention was inversely correlated with the FA values for the posterior limb of the internal capsule, ACR, SLF, and ILF. CONCLUSION: The results indicated that the presence of white matter changes during the early stage of DAI may be helpful for predicting cognitive dysfunction over the long term. LEVEL OF EVIDENCE: Prognostic study, level III.