Possibility and challenge of plant-derived ferritin cages encapsulated polyphenols in the precise nutrition field.

Polyphenols have attracted extensive attention due to their rich functional activities, such as antioxidant, anti-inflammatory and anti-tumor. However, the low solubility and poor stability limit their bioavailability and functional activities. Plant-derived ferritin cages have a unique hollow cage structure that can embed polyphenols to improve their unfavorable properties. Therefore, it is essential to adequately elaborate and summarize plant-derived ferritin cages to maximize their potential benefits in nutritional interventions. This review focuses on the fundamental properties of plant-derived ferritin cages, including the preparation process, purification technology, identification methods, and structural and functional properties. The relevant research on ferritin cages in polyphenol delivery has been summarized, including the delivery of water/lipid soluble polyphenols, modification of ferritin cages, and the interaction between polyphenols and ferritin cages. The research progress, shortcomings and prospects of plant-derived ferritin cages in precise nutrition are introduced. In addition, the relevant research on ferritin in immune response and protein engineering is also discussed to provide the theoretical basis for applying plant-derived ferritin cages in many frontier fields.

Toxicity and oxidative stress of HepG2 and HL-7702 cells induced by PAH4 using oil as a carrier.

Polycyclic aromatic hydrocarbons (PAHs), a widespread class of food pollutants, are commonly exposed to humans along with edible oil. The dietary exposure pattern of PAH4 was simulated to study the toxicity and oxidative stress of oil-based PAH4 on hepatocytes. The findings demonstrated that oil-based PAH4 induced cell viability and mitochondrial membrane potential decreased and promoted apoptosis and oxidative stress in a concentration-dependent manner. Benzo[a]pyrene had the strongest toxicity and HL-7702 cells were more sensitive to toxicity than HepG2 cells, due to differences in induced CYP1A enzyme activity. Oil-based PAH4 had greater cytotoxicity than PAH4, attributed to the synergistic effect of oil and PAH4. Furthermore, oil-based PAH4 induced oxidative stress in HepG2 and HL-7702 cells through the same AHR-Nrf2-KEAP1 pathway, which was elucidated by detecting genes and proteins expression. This study lays the foundation for elucidating the harm of dietary exposure to PAHs and reminds us that food composition may increase the harm of PAHs.

Combined toxicity of oil-based PAH4 mixtures on HL-7702 cells.

Polycyclic aromatic hydrocarbons (PAHs) as a group of prevalent persistent organic pollutants in the environment are always found as mixtures. The combined toxicity of oil-based PAH4 seems seldom to be mentioned. To evaluate the combined toxicity of oil-based PAH4 mixtures on HL-7702 cells, the effects of single, binary, ternary, and quaternary mixtures on cell viability were examined, and the concentration addition model and combination index (CI)-isobologram model were selected to predict the toxicological interactions of the mixtures. The results showed that the PAH4 mixtures had a concentration-dependent effect on cell viability. The CI model was more suitable for elucidating the toxicity interactions of mixtures. In addition, the combined toxicity of BaA + BaP and BaA + Chr + BbF + BaP was antagonistic, BaA + Chr, BaA + BbF, Chr + BbF, and BaA + Chr + BbF was synergistic, and the remaining mixtures shifted from antagonistic to synergistic. Antagonistic effects were observed in all mixtures containing BaP, indicating that oil-based PAH4 mixtures containing BaP had a mitigating effect on cytotoxicity. Furthermore, BbF was identified as playing a key role in the synergistic effects in binary and ternary mixtures. This study provided a new acknowledgment to assess the interactions of PAH4 mixtures which is helpful for further study of the toxicity risks in the environment.

Walnut Protein: A Rising Source of High-Quality Protein and Its Updated Comprehensive Review.

Recently, plant protein as a necessary nutrient source for human beings, a common ingredient of traditional processed food, and an important element of new functional food has gained prominence due to the increasing demand for healthy food. Walnut protein (WP) is obtained from walnut kernels and walnut oil-pressing waste and has better nutritional, functional, and essential amino acids in comparison with other vegetable and grain proteins. WP can be conveniently obtained by various extraction techniques, including alkali-soluble acid precipitation, salting-out, and ultrasonic-assisted extraction, among others. The functional properties of WP can be modified for desired purposes by using some novel methods, including free radical oxidation, enzymatic modification, high hydrostatic pressure, etc. Moreover, walnut peptides play an important biological role both in vitro and in vivo. The main activities of the walnut peptides are antihypertensive, antioxidant, learning improvement, and anticancer, among others. Furthermore, WP could be applied in the development of functional foods or dietary supplements, such as delivery systems and food additives, among others. This review summarizes recent knowledge on the nutritional, functional, and bioactive peptide aspects of WP and possible future products, providing a theoretical reference for the utilization and development of oil crop waste.

Formation, migration, derivation, and generation mechanism of polycyclic aromatic hydrocarbons during frying.

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and lipophilic, which can be found in frying system. This review summarized the formation, migration and derivation for PAHs, hypothesized the possible mechanism for PAHs generation during frying and presented the research prospects. Some factors like high oil consumption, high temperature, long time and oil rich in unsaturated fatty acids promoted the formation of PAHs and the presence of antioxidants inhibited the PAHs formation. The effect of proteins and carbohydrates in foods on the formation of PAHs is inconclusive. The formed PAHs were migrated into food and air. Moreover, some PAHs transformed into more toxic PAHs-derivatives during frying. The generation of PAHs may be related to low-barrier free radical-mediated reaction and the unsaturated hydrocarbons may be precursors of PAHs during frying. In future, the isotope tracer technology and on-line detection may be applied to discover intermediates and provide clues for studying PAHs generation mechanisms.

Subcritical Water Enhanced with Deep Eutectic Solvent for Extracting Polysaccharides from Lentinus edodes and Their Antioxidant Activities.

In the present study, subcritical water extraction (SWE) assisted with deep eutectic solvent (DES) is used to extract Lentinus edodes polysaccharides (LEP). In addition, the antioxidant activity of the polysaccharide samples was also investigated. Based on a single factor test and response surface test, the optimal extraction factors were a liquid-solid solvent of 40:1 mL/g, extraction temperature of 147.23 °C, water content of 39.76% and extraction time of 17.58 min. Under these extraction conditions, the yield of LEP was 6.26 ± 0.08%. Compared with the SWE and hot water extraction (HWE), it improved by 19.24% and 17.01%, respectively. In addition, the results of monosaccharide composition, molecular weight, FT-IR, UV and SEM confirmed that the extracts had the features of polysaccharides. Interestingly, the polysaccharides obtained with the SWE assisted with the DES procedure showed a higher DPPH scavenging activity, hydroxyl radical scavenging activity and hydrogen peroxide scavenging activity, which indicated that the polysaccharides with this method had a stronger antioxidant activity. These findings demonstrated that the SWE-assisted DES is a strong method to obtain polysaccharides from Lentinus edodes for food, biopharmaceutical and other industrial production.

Migration and Distribution of PAH4 in Oil to French Fries Traced Using a Stable Isotope during Frying.

Isotope-labeled four polycyclic aromatic hydrocarbons (PAH4-d12) were applied to study the migration and distribution of PAH4 in oil to French fries during frying. The results showed that the mobilities of PAH4-d12 showed a downtrend within 0-6 h and then an uptrend, and PAH4-d12 were mainly distributed in the crust of the French fries, especially five-ring PAHs-d12. The correlation analysis showed that PAH4-d12 migration was mainly caused by oil absorption of French fries. The low fluidity of the oil slowed down the PAH4-d12 migration, which was accelerated as the total polar component increased (higher than 15-20%). Additionally, higher frying temperature enhanced the crust ratio and porous structure of French fries, which explained the abundant five-ring PAHs-d12 distributed in the crust. This study provided references for optimizing the frying parameters: the exposure of PAH4 in French fries to humans can be reduced by controlling the oil quality and weakening the crust of the French fries.

Properties of selenium nanoparticles stabilized by Lycium barbarum polysaccharide-protein conjugates obtained with subcritical water.

Selenium nanoparticles (SeNPs) in an aqueous solution have poor stability and tend to aggregate when stored for a long time. In the present study, SeNPs were stabilized by using Lycium barbarum polysaccharide (LBP) and Lycium barbarum protein (LBPr) conjugates (LBPP) as a stabilizer and dispersing agent. Particularly, the LBPP1 was obtained with subcritical water treatment. In addition, the physical stability, re-dispersity and antitumor activity of LBPP1-SeNPs were investigated. The results showed the particle size of LBPP1-SeNPs was maintained at 111.5-117 nm, which was stable at PH 6, 4 °C and darkness for at least 40 days. Besides, the result of TEM showed that the dispersion of LBPP1-SeNPs had more clear layers and smoother surfaces. Moreover, LBPP1-SeNPs had excellent re-dispersibility and exhibited a significant inhibitory effect on HepG-2 cells and Caco-2 cells, respectively (p < 0.05). Therefore, LBPP1-SeNPs can be used as potential selenium nutritional supplements for food and medical applications.

Current Progress in the Extraction, Functional Properties, Interaction with Polyphenols, and Application of Legume Protein.

Legume protein can replace animal-derived protein because of its high protein content, low price, lack of cholesterol, complete amino acids, and requirements of vegetarianism. Legume protein has not only superior functional properties but also high biological activities. Therefore, it is widely used in the food industry. However, there are few studies on the comprehensive overview of legume protein. In this review, the extraction, functional properties, interaction with polyphenols, application of legume protein, and activities of their peptides were comprehensively reviewed. Legume proteins are mainly composed of globulin and albumin. The methods of protein extraction from legumes mainly include wet separation (alkali solution and acid precipitation, salt extraction, enzyme extraction, and ultrasonic-assisted extraction) and dry separation (electrostatic separation). Besides, various factors (heat, pH, and concentration) could significantly affect the functional properties of legume protein. Some potential modification technologies could further improve the functionality and quality of these proteins. Moreover, the application of legume protein and the effects of polyphenols on structural properties of legume-derived protein were concluded. Furthermore, the bioactivities of peptides from legume proteins were discussed. To improve the bioactivity, bioavailability, and commercial availability of legume-derived protein and peptides, future studies need to further explore new preparation methods and potential new activities of legume-derived proteins and active peptides. This review provides a real-time reference for further research on the application of legume protein in the food industry. In addition, this review provides a new reference for the development of legume-derived protein functional foods and potential therapeutic agents.

Study on the structure-activity relationship of watermelon seed antioxidant peptides by using molecular simulations.

Our previous studies had shown that watermelon seed antioxidant peptides (WSAPs: P1-P5) possessed good activities. However, the structure-activity relationship of P1 is still unclear. Quantum chemistry and molecular docking were used to investigate the antioxidant mechanism of P1. The active site of P1 is located at C6H14 on Arg. P1 can bind to DPPH/ABTS through hydrogen bond and hydrophobic interaction. Compared with P2-P4, P1 has the strongest antioxidant capacity. The molecular simulation showed that P1 could enhance the stability of Keap1 by interacting with Asn382, Arg380 and Tyr 334 in the active sites. Compared with the model group, the expression of Keap1 was down-regulated (p < 0.05), while the expression of Nrf2 and HO-1 was up-regulated (p < 0.05) after P1 treatment. P1 has the potential ability to activate the signaling pathway Keap1-Nrf2 and improve the antioxidant defense system. This study provides a new perspective for the rational design and mechanism of antioxidant peptides.

Purification, characterization, antioxidant and immunological activity of polysaccharide from Sagittaria sagittifolia L.

As a healthy food and traditional Chinese medicine, sagittaria sagittifolia L. has been used for a long history. Nevertheless, reports on the bioactivity and chemical characterization of S. sagittifolia L. polysaccharides are still very rare. In this paper, ultrasound-assisted method (UAE) was used to extract S. sagittifolia L. polysaccharides, after alcohol precipitation and column chromatography isolation, the structural characteristics, antioxidant and immunological activities of the purified polysaccharide (SPU60-W) were preliminarily investigated. The results indicated SPU60-W (16.62 kDa) was a pyranoid polysaccharide containing α-glycosidic bond composed of mannose, xylose, and glucose with a molar ratio of 2.69: 2.04: 95.27. It consisted of slender wormlike strands, which may involve some degree of aggregation of helices, as well as a small proportion of irregular spherical structures. Furthermore, antioxidant activity analysis showed that SPU60-W possess excellent hydroxyl and ABTS radical scavenging activity comparable to vitamin C (Vc), and moderate DPPH radical scavenging activity. Immunity tests suggested that SPU60-W significantly promoted the proliferation, phagocytosis and NO production of mouse macrophage RAW264.7. According to this study, SPU60-W might be utilized as a potent antioxidant and immunomodulator in food and medicinal industry.

Structure and functional properties of soy protein isolate-lentinan conjugates obtained in Maillard reaction by slit divergent ultrasonic assisted wet heating and the stability of oil-in-water emulsions.

Effects of a novel slit divergent ultrasound (SDU) treatment on soybean protein isolate (SPI)-lentinan conjugates via Maillard reaction was investigated. Besides, the stability of emulsions prepared by SPI and SPI-lentinan conjugates (ultrasound and un-ultrasound) as emulsifiers was compared. The results showed that ultrasonic treatment (40 min) markedly increased the degree of grafting (26.48%) by 1.91 times comparing with traditional heating method (2 h, 13.89%). In addition, structural analysis showed that the conjugates obtained by SDU treatment changed the secondary structure and had higher surface hydrophobicity and fluorescence intensity than those obtained by traditional heating method. Apart from this, SDU treatment could significantly improve the functional properties (solubility, foaming, emulsifying capacity, thermal stability, and viscosity) of conjugates. Furthermore, the emulsions prepared by the SPI-lentinan conjugates (ultrasound) as emulsifiers possessed the highest stability against environmental stresses. Taken together, SDU-assisted heating could be an excellent method to improve the functional properties of conjugates.

Purification and identification of novel antioxidant peptides from watermelon seed protein hydrolysates and their cytoprotective effects on H2O2-induced oxidative stress.

The aim of this study was to purify and identify antioxidant peptides from watermelon seed protein hydrolysates (WSPHs-I: Mw < 1 kDa) and further evaluate their cytoprotective effects against H2O2-induced oxidative stress in HepG2 cells. After purification by Sephadex G-15 and semi-preparative reversed-phase high performance liquid chromatography (RP-HPLC), five peptides, RDPEER (P1), KELEEK (P2), DAAGRLQE (P3), LDDDGRL (P4), and GFAGDDAPRA (P5) were sequenced by LC-MS/MS and synthesized with solid-phase synthesis method. These peptides showed desirable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity (IC50: 0.216 ± 0.01-0.435 ± 0.03), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity (IC50: 0.54 ± 0.02-1.23 ± 0.03), and oxygen radical absorbance capacity (ORAC) (82.36 ± 1.2-130.67 ± 2.2 µM TE/mg). Among them, peptide P1 exhibited the strongest antioxidant capacity. Moreover, the results suggested that peptide P1 may protect HepG2 cells from H2O2-induced oxidative damage by significantly inhibiting reactive oxygen species (ROS), [Ca2+]i, malondialdehyde (MDA) levels and increasing antioxidative enzyme activities.

Slit divergent ultrasound pretreatment assisted watermelon seed protein enzymolysis and the antioxidant activity of its hydrolysates in vitro and in vivo.

Watermelon seed, a watermelon processing industry by-product, is a good protein source for the preparation of antioxidant peptides due to its high protein content, low cost, special amino acid composition. Antioxidant hydrolysates obtained from watermelon seed protein (WSP) after slit divergent ultrasound (SDU) treatment were studied. The stepwise multiple linear regression model verified that the reducing power of watermelon seed protein hydrolysates (WSPHs) is positively related with -SH and ß-turn content of WSP (R2 = 0.931, p < 0.01). Using the degree of hydrolysis (DH) and reducing power as indicators, the WSPHs was prepared under the optimal conditions (ultrasound frequency: 20/28 kHz, time: 60 min, power density: 100 W/L) and divided into three components by ultrafiltration membrane (1 and 5 kDa). Compared with WSPHs and other fractions, WSPHs-I (Mw < 1 kDa) not only significantly protected HepG2 cells from H2O2-induced damage, but also greatly alleviated the liver injury caused by d-galactose in male SD rats.

Antioxidant activity of arrowhead protein hydrolysates produced by a novel multi-frequency S-type ultrasound-assisted enzymolysis.

Effects of multi-frequency S-type ultrasound (MFSU) assisted arrowhead protein (AP) hydrolysis on the antioxidant activity of its hydrolysates were studied. The results showed the DPPH• and ABTS•+ scavenging activity of hydrolysates obtained with dual frequency ultrasound (20/40 kHz) was 63.61% and 65.11%, respectively, and was higher than that noted for hydrolysates acquired with assistance of other mode (single and triple frequency ultrasound). Compared with hydrolysates without ultrasonic treatment, products of AP hydrolysis assisted by dual frequency ultrasound (20/40 kHz) could significantly alleviate oxidative stress induced by H2O2 in RAW 264.7 cells, mainly embodied in improving the survival rate and increasing the activity of antioxidant enzymes (CAT and SOD). Taken together, these results showed that MFSU-assisted enzymatic treatment can significantly improve the antioxidant activity of AP hydrolysates. Thus, the development of the novel MFSU could lay a foundation for assisting the protein enzymolysis in food and pharmaceutical industries.

Review of isolation, structural properties, chain conformation, and bioactivities of psyllium polysaccharides.

Polysaccharides isolated from natural products, have raised an increasing interest due to their variety of beneficial health effects. Plantago spp., a valuable Chinese herbal plant, has a long history of cultivation and is widely accepted as traditional herbal medicines and functional foods in Asian counties. Polysaccharide is a very important biological active ingredient in the Plantago spp., which has a variety of biological effects, including immunomodulatory, antioxidant, antitumor, and hypoglycemic activities, among others. A large number of articles have been reported the structural identification and activity evaluation of psyllium polysaccharides. However, the structure-activity relationship of psyllium polysaccharides has not been well established. Therefore, this review focused on the extraction, purification, structural characterization, chain conformation, and biological activities of psyllium polysaccharides, which can provide useful research underpinnings and updated information for the development and application of related polysaccharides in functional foods and medicinal field.

Antioxidant Peptide Fractions Isolated from Wheat Germ Protein with Subcritical Water Extraction and Its Transport Across Caco-2 Cells.

Wheat germ protein (WGP) was extracted with subcritical water and then hydrolyzed with Alcalase 2.4 L to obtain antioxidant hydrolysates. Wheat germ peptides (WG-P, Mw < 1 kDa) were purified by using Sephadex G-15 column chromatography. The results showed that WG-P-4 possessed the strongest DPPH radical scavenging activity in comparison with other peptides fractions. In addition, free amino acids and LC-MS/MS analysis showed that Gly-Pro-Phe, Gly-Pro-Glu, and Phe-Gly-Glu were the major peptides of WG-P-4. Interestingly, the WG-P-4 fractions had good absorption characteristic. Moreover, the ratio of Papp both sides of apical compartment (AP) and basolateral compartment (BL) were between 0.5 and 1.0 on Caco-2 cell model, which indicated that transmembrane transportation was mainly passive transport. Therefore, WG-P could exert an effective antioxidant action by across the intestinal epithelium.

Effects of divergent ultrasound pretreatment on the structure of watermelon seed protein and the antioxidant activity of its hydrolysates.

In the present study, the antioxidant hydrolysates obtained from watermelon seed protein (WSP) after divergent ultrasound and ultrafiltration treatment were studied. The results showed that the slit divergent ultrasound (SDU, 20/28 KHz) pretreatment had considerable influence on the structure and enzymatic efficiency of WSP. Besides, compared with hydrolysates without ultrasonic and ultrafiltration treatment, watermelon protein hydrolysates with molecular weight <1 kDa (WSPHs-I) showed the highest antioxidant activities and could protect RAW 264.7 cells from H2O2-induced oxidative stress damage via activating the Nrf2/HO-1 pathway. Interestingly, WSPHs-I had good stability against oxidation at temperature under 100 °C or in the acidic or neutral condition and still exhibited strong antioxidant activity after simulated gastrointestinal digestion. Taken together, SDU pretreatment could significantly increase the antioxidant activities and stability of WSPHs by improving the structure and facilitating enzymolysis of the WSP.

Advance in Cordyceps militaris (Linn) Link polysaccharides: Isolation, structure, and bioactivities: A review.

Cordyceps militaris is a unique and precious medical fungus in Chinese Cordyceps, which has been widely used as the traditional medicines or as biocontrol agents against pests in China for centuries. Polysaccharides are one of bioactive constituents in Cordyceps militaris with a variety of biological activities, including immunomodulation, antioxidant, anti-tumor, and anti-aging activities, among others. However, natural Cordyceps militaris are very rare and expensive, most of literatures indicated that the polysaccharides were mostly extracted from artificially cultivated fungal fruiting bodies (intracellular polysaccharides) or mycelia fermentation broths (extracellular polysaccharides). Moreover, separation and purification of polysaccharides was a very complicated and cumbersome process. Nevertheless, a large number of polysaccharides were purified and its characterization was elucidated by structure and biological activities. However, the relationship between structure and activity of polysaccharides has not been well established. Therefore, this review detailed the recent advance in several aspects (i.e., extraction, isolation, structure, and bioactivities) of the polysaccharides from fruiting body of Cordyceps militaris. This information could provide theoretical basis for the research on related polysaccharides, and also have important reference value in the field of functional foods and medicine in the future.

Structural characterization and immunostimulatory activity of a novel polysaccharide isolated with subcritical water from Sagittaria sagittifolia L.

In the present study, we obtained polysaccharides from Sagittaria sagittifolia L. (SSP) with subcritical water extraction (SWE). Two water-soluble polysaccharides (SSP-W1 and SSP-S1) from the acquired SSP were isolated with DEAE-52 and Sephadex G-100. Besides, the structural characteristics and immunostimulatory activity were also investigated. The results showed that both SSP-W1 and SSP-S1 were homogeneous polysaccharides and the molecular weight was 62.03 KDa and 15.2 KDa, respectively. In addition, both SSP-W1 and SSP-S1 are heteropolysaccharides. Moreover, FT-IR analysis showed that SSP-W1 was α-pyranose polysaccharide, while SSP-S1 was a typical ß-pyranose polysaccharide. Congo red staining showed that there was no triple helix structure in both SSP-W1 and SSP-S1. Furthermore, both SSP-W1 and SSP-S1 could promote the proliferation, production of NO, and secretion of TNF-α and IL-10 of macrophages RAW 264.7, significantly. Therefore, the polysaccharides extracted from Sagittaria sagittifolia L. with SWE have the potential to be used as immunoreactive agent in medicine and functional foods.