Enhancing functionality and bioactivity of walnut protein through limited enzyme digestion.

BACKGROUND: Walnut protein (WP) is recognized as a valuable plant protein. However, the poor solubility and functional properties limit its application in the food industry. It is a great requirement to improve the physicochemical properties of WP. RESULTS: Following a 90 min restricted enzymatic hydrolysis period, the solubility of WP significantly increased from 3.24% to 54.54%, with the majority of WP hydrolysates (WPHs) possessing a molecular weight exceeding 50 kDa. Circular dichroism spectra showed that post-hydrolysis, the structure of the protein became more flexible, while the hydrolysis time did not significantly alter the protein's secondary structure. After hydrolysis, WP's surface hydrophobicity significantly increased from 2279 to 6100. Furthermore, WPHs exhibited a strong capacity for icariin loading and micelle formation with critical micelle concentration values of 0.71, 0.99 and 1.09 mg mL-1, respectively. Moreover, similar immuno-enhancement activities were observed in WPHs. After exposure to WPHs, the pinocytosis of RAW264.7 macrophages was significantly improved. WPH treatment also increased the production of nitric oxide, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in macrophages. Up-regulation of mRNA expressions of IL-6, inducible nitric oxide synthase (iNOS) and TNF-α was observed in a dose-dependent manner. CONCLUSION: The enhancement of functionality and bioactivity in WP can be achieved through the application of limited enzyme digestion with trypsin. This process effectively augments the nutritional value and utility of the protein, making it a valuable component in various dietary applications. © 2024 Society of Chemical Industry.

From Epimedium to Neuroprotection: Exploring the Potential of Wushanicaritin.

Epimedium has been used for functional foods with many beneficial functions to human health. Wushanicaritin is one of the most important chemicals int Epimedium. This study investigated the neuroprotective effects of wushanicaritin and potential underlying mechanisms. The results demonstrated that wushanicaritin possessed superior intercellular antioxidant activity compared to icaritin. Wushanicaritin, with an EC50 value of 3.87 µM, showed better neuroprotective effect than quercetin, a promising neuroprotection agent. Wushanicaritin significantly reversed lactate dehydrogenase release, reactive oxygen species generation, cell apoptosis, and mRNA expression related to cell apoptosis and oxidative defense, in glutamate-induced PC-12 cells. Wushanicaritin could also maintain the enzymatic antioxidant defense system and mitochondrial function. The suppression of caspase-3 activation and amelioration of mitochondrial membrane potential loss and nucleus morphology changes were involved in the antiapoptotic effect of wushanicaritin. These findings suggested that wushanicaritin possesses excellent intercellular antioxidant and neuroprotective activities, showing potential promise in functional foods.

Degree of methyl esterification: A key factor for the encapsulation of icaritin with pectin.

Pectin is a promising nano-carrier. The degree of methyl esterification (DM) influences the physiochemical properties of pectin. However, the effect of DM on the encapsulation capacity of pectin remains unclear. In this work, low methyl-esterified pectin (LMP) and high methyl-esterified pectin (HMP) were prepared. The molecular weight, rheological properties of these pectins with various DM levels were determined. Then icaritin/pectin micelles (IPMs) were prepared using HMP and LMP. Notably, higher loading capacities (18.75-20.12 %) were observed in HMP-IPMs compared to LMP-IPMs (15.72-16.64 %). Furthermore, LMP-IPMs demonstrated a DM-dependent reduction in particle sizes, ranging from 449 to 527 nm. In contrast, the particle sizes of HMP-IPMs varied between 342 and 566 nm, with smaller particle sizes observed in HMP-IPMs at higher DM levels. A significant positive correlation was found between DM and the formation of IPMs, including encapsulation efficiency, loading capacity, Zeta potential, and polydispersity index. Alkali de-esterification showed a weak impact on the pectin structure. Hydroxyl groups like 7-OH and 5-OH of icaritin might be involved in the formation of IPMs. The hydrogen-bond interactions between pectin and icaritin could be enhanced as DM increased.

Interaction between ultrasound-modified pectin and icaritin.

Pectin can improve the bioaccessibility of icaritin as a nanocarrier, and ultrasound can modify the pectin structure. However, the interaction between ultrasound-modified pectin (UMP) and icaritin remains unclearly. In this work, the effects of UMP on the physiochemical properties of icaritin/pectin micelles (IPMs) were investigated. The IPMs prepared with UMP (UMP-IPMs) showed lower encapsulation efficiencies and loading capacities, comparing with native IPMs. UMP-IPMs had smaller particle sizes (325-399 nm) than native IPMs (551 nm). The Mw, viscosity, G' and G" of pectin were determined. NMR spectra indicated that the repeating unit in pectins remained consistently before and after ultrasound treatment, and 7-OH of icaritin was involved in hydrogen bond formation with pectin. The larger chemical shift movement of 6-H and 7-OH for U3-IPMs than P0-IPMs suggested that stronger hydrogen bond interaction between icaritin and pectin. UMP-IPMs exhibited stronger anti-proliferation activities against HepG2 cells than native IPMs.

Fabrication of icariin-soymilk nanoparticles with ultrasound-assisted treatment.

Ultrasound is effective to fabricate nanocomplex. Soymilk is a natural nanocarrier with good compatibility. However, information about soymilk-nutraceuticals nanocomplex is limited. In this work, soymilk was used to encapsulate icariin, a well known nutraceutical with poor bioavailability. The effect of ultrasound on the quality of icariin-soymilk nanocomplexes (ISNCs) was investigated. Ultrasound could reduce the particle size, improve the surface hydrophobicity and change the microstructure of soymilk. With increasing ultrasound treatment time, an increased surface hydrophobicity was observed. The highest encapsulation efficiency (89.67 %) and loading capacity (28.92 µg/mg) were found for USI-20, whereas the smallest particle size (132.47 nm) was observed for USI-120. USI-60 showed the lowest ζ-potential (-31.33 mV) and the highest bioaccessibility (76.08 %). Ultrasound could enhance the storage stability of ISNCs. The data of NMR and fluorescence indicated that ISNCs were mainly stabilized by hydrophobic interaction.

The chemical composition and toxic effects of aqueous extracts of Cyclocarya paliurus leaves.

Cyclocarya paliurus leaves, which possess various bioactivities, have been widely used in dietary supplements or as ingredients in functional foods. However, limited information is available about the toxicity or safety concerns. In the present work, the maximum tolerated dose (MTD) and potential toxicity of the aqueous extracts of C. paliurus leaves (AECPL) were evaluated. Our results indicated that AECPL was rich in phenolics, flavonoids, and polysaccharides, which might be responsible for the health benefits of C. paliurus leaves. The MTD of AECPL was considered to be > 10,000 mg/kg BW in both male and female rats. The acute toxicity study was carried out by a 14-day repeat dose oral toxicity study. The results showed that the rats were all well-tolerated. No treatment-related mortality, abnormal clinical signs, body weight, or food consumption changes were reported during the study. Moreover, AECPL showed no adverse changes in the hematology, serum chemistry, urinalysis parameters, organ weights, gross finding, and histopathology. In this study, the non-observed-adverse-effect level of AECPL was 5,000 mg/kg BW/day, indicating AECPL was safe and can be used in the food industry.

Structure identification of walnut peptides and evaluation of cellular antioxidant activity.

Walnut peptides are widely accepted as nutraceuticals with multiple health benefits. However, information about the structure and biological activity of walnut peptides is limited. In this work, walnut protein hydrolysate (WPH) was prepared by enzymatic hydrolysis. The total and free amino acids compositions in WPH were determined. The peptides sequence of WPH was analyzed by UPLC-MS/MS, and forty eight bioactive peptides were identified. Antioxidant activities were detected for WPH in both extracellular and intercellular assays. QGRPWG, PSRADIY and AYNIPVNIAR were the peptides that accounted for the antioxidant activity of WPH. Among them, QGRPWG showed the highest ORAC value (2801 µmol TE/g), and AYNIPVNIAR possessed the strongest protective effect against H2O2-induced oxidative stress in PC-12 cells in a dose-dependent manner. The results can aid in the recognition of peptides from walnut as nutraceuticals.

Structure characterization of soybean peptides and their protective activity against intestinal inflammation.

Soybean peptides serve as functional foods with impressive health benefits. The structure characteristics of peptides are highly related to the health benefits. The structure-activity relationship and mechanism underlined are important scientific questions in this field. To answer these questions, soybean peptides were produced by combinatory enzymatic hydrolysis in this work. Fifty-two peptide sequences were identified by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The anti-inflammatory activities of these peptides were investigated by using a lipopolysaccharide (LPS)-induced inflammation cell model. Soybean peptides could significantly promote cell proliferation. Additionally, soybean peptides could alleviate LPS-induced inflammation by reducing the production and expression of nitric oxide (NO), tumor necrosis factor alpha (TNF-α), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6). Moreover, soybean peptides could promote the mRNA expression of proteins related to inflammation inhibition (IL-10) and tight junction modulation. The structure-activity relationship was addressed. The results documented the potential of soybean peptides as functional foods.

Structure identification of a polysaccharide in mushroom Lingzhi spore and its immunomodulatory activity.

Ganoderma lucidum spore serves as a well-known immunomodulatory functional food in Asia. The polysaccharides in G. lucidum spore are responsible for the claimed immunomodulatory activity. However, the structural information of polysaccharides remains unclear. In this work, the leading water-soluble polysaccharide in G. lucidum spore (GLSP-I) with a molecular weight of 128.0 kDa was isolated and purified. The monosaccharide composition analysed by gas chromatography indicated that GLSP-I was a glucan. Three side chains, including Glc-(1 â†’ 3)-Glc-(1 â†’ 3)-Glc-(1 â†’ 6)-Glc, Glc-(1 â†’ 6)-Glc-(1 â†’ 6)-Glc-(1 â†’ 6)-Glc and Glc-(1 â†’ 3)-Glc-(1 â†’ 3)-Glc-(1 â†’ 3)-Glc-(1 â†’ 3)-Glc, were identified by UPLC-MS/MS. The structural characteristics were further identified by NMR spectra. The results indicated that the backbone of GLSP-I was (1 â†’ 3)-ß-D-glucan, with side chains linking at O-6. The proposed structure was drawn as below. The immunomodulatory activity assay indicated that GLSP-I could activate macrophages in a dose-dependent manner.

Prenylated flavonoids in foods and their applications on cancer prevention.

Functional foods play an important role in health care and chronic diseases prevention, particularly cancer. Prenylated flavonoids are presented in many food resources. They are recognized as neutraceuticals due to their diverse health benefits. Up to now, more than 1000 prenylated flavonoids have been identified in plants. Their food resources are reviewed in this paper. Due to the good safety and cancer prevention effect of prenylated flavonoids, this paper reviews the cancer prevention activities and mechanisms reported in last decade. The structure-activity relationship is discussed. Due to the limited availability in nature, the heterologously biosynthetic technique of prenylated flavonoids is discussed in this review. Inclusion of dietary prenylated flavonoids into human diet is highly desirable. This paper combines the up-to-date information and give a clear image regarding prenylated flavonoids as neutraceuticals.

Structure of water-soluble polysaccharides in spore of Ganoderma lucidum and their anti-inflammatory activity.

Ganoderma lucidum spore is widely accepted as functional food. Polysaccharides are the predominant bioactive components in G. lucidum spore and contribute much to its health benefits. However, their structural characteristics remain unclear. In this work, water-soluble polysaccharides (GLSP) were obtained by hot water extraction. Three monosaccharides, including arabinose (Ara), glucose (Glc) and galactose (Gal), were presented in GLSP. 1D and 2D NMR data revealed that GLSP were composed mainly by two polysaccharides, ß-glucan and arabinogalactan. The arabinogalactan had a backbone of galactan with Araf in the side chain. ß-Glucan was the dominant polysaccharide in G. lucidum spore. The molecular weight was measured. GLSP could induce IEC-6 cells proliferation in a concentration-dependent manner. Moreover, GLSP possessed a strong anti-inflammatory activity through inhibiting the overproduction of NO and pro-inflammatory cytokines, like interleukin-6 (IL-6) and interleukin-1ß (IL-1ß) induced by LPS. These results implied the potential of GLSP on gut barrier protection.

Characterization of polysaccharide structure in Citrus reticulate 'Chachi' peel during storage and their bioactivity.

The peel of Citrus reticulate 'Chachiennsis' (Chachi) is widely accepted as a functional food. It is generally recognized that its health benefits are dependent on storage time. However, the chemicals responsible for this phenomonon remain unclear. As bioactive polysaccharides are dominant in Chachi, Chachi polysaccharides with various storage times (5-20 years) were prepared. The monosaccharide composition was analyzed by GC-MS. NMR data revealed that Chachi polysaccharides were mainly consisted of arabinogalacturonan and another pectin with side chain of →4)-ß-D-Galp-(1 â†’ . α-L-Araf-(1→, →5)-α-L-Araf-(1→, →4)-α-D-GalpA-(1→, →4)-α-D-GalpAMe-(1→, →4)-ß-D-Galp-(1→ and →4)-ß-D-Glcp-(1→ were detected. The molecular weight of Chachi polysaccharides decreased along with the extension of storage time. However, the basic structure characteristics remained stable. The immumomodulatory activities of Chachi polysaccharides were improved as the storage time extended. The change of molecular weight was responsible for the improved immunomodulatory activity. The results explained how polysaccharides contributed to the enhanced health benefits of Chachi during storage.

Identification of prenylated phenolics in mulberry leaf and their neuroprotective activity.

BACKGROUND: Neurodegenerative diseases are becoming increasingly prevalent over the world. Therefore, drug development in this field is urgently required. Neuron impairment leads to the pathogenesis of neurodegenerative diseases, while amelioration of oxidative stress can inhibit the impairment. As a traditional Chinese medicine, mulberry leaf exhibits various pharmacological properties, including neuroprotective activity. But the major components responsible for the neuroprotective activity of mulberry leaf remained unknown. Phytochemicals were potent candidates of neuroprotective drug. Prenylated phenolics are the leading phytochemicals present in mulberry leaf. PURPOSE: The aim of this study was to investigate the neuroprotective activities and mechanisms of prenylated phenolics. METHODS: The chemical structure of isolated compounds were elucidated by MS and NMR. UPLC-MS/MS was used to determine the contents of prenylated phenolics in fresh mulberry leaf. Neurotoxicity was induced by erastin in HT22 cells. CCK-8 assay was performed to assess cell viability. ROS production, GSH level and iron release were monitored by using DCFH-DA, monobromobimane, and FeRhoNox™-1, respectively. qRT-PCR and Western blotting assays were performed to assess gene and protein expression, respectively. RESULTS: Four prenylated phenolics, including isobavachalcone, morachalcone B, moracin N and morachalcone A were isolated and identified from mulberry leaf. Their levels in fresh mulberry leaf were in a decreasing order, moracin N > morachalcone A > morachalcone B > isobavachalcone. Moreover, moracin N showed a good neuroprotective activity with an EC50 < 0.50 µM. The neuroprotective mechanisms of moracin N included inhibition of glutathione depletion, glutathione peroxidase 4 (GPx4) inactivation, reactive oxygen species (ROS) overproduction and iron accumulation, as well as improvement of intracellular antioxidant enzyme activities. Moracin N augmented the transcriptional levels of genes involved in antioxidant defense and glutathione biosynthesis in the early state of ferroptosis induction, and downregulated expression of genes related to iron accumulation and lipid peroxidation. CONCLUSION: The results confirmed that moracin N was a good ferroptosis inhibitor, which exerted neuroprotective activity through preventing from oxidative stress.

Structure identification of soybean peptides and their immunomodulatory activity.

Soybean peptides are functional food with good health benefits. The health benefits presented are highly dependent on the peptide structure. In this work, soybean peptides were prepared by alkaline protease hydrolysis of soybean proteins. The peptide structure was identified by UPLC-MS/MS. The full peptide composition was revealed. The sequences of 51 peptides were identified and 46 peptides were assigned as immunomodulatory peptides. By evaluating the immumonodulatory activity and mechanism, soybean peptides could facilitate the proliferation of macrophages. The pinocytotic activity and NO level were increased. Induction of iNOS mRNA expression by soybean peptides was responsible for the increased NO production. The release of cytokines IL-6 and TNF-α was elevated and their levels were equal to positive control. The mRNA expression levels of IL-6 and TNF-α were also improved by soybean peptides, but much lower than positive control. The results were helpful for application of soybean peptides in functional foods.

Structural characterization of Lanzhou lily (Lilium davidii var. unicolor) polysaccharides and determination of their associated antioxidant activity.

BACKGROUD: The Lanzhou lily (Lilium davidii var. unicolor) is the only Lilium species that is used for both culinary and medicinal purposes in China. Its bulbs contain various bioactive substances, such as polysaccharides, saponins and colchicine. Lanzhou lily polysaccharides are known to have anti-immunity, anti-tumor and anti-oxidation functions. RESULTS: The present study used a Box-Behnken design to optimize the ultrasound-assisted extraction of Lanzhou lily polysaccharides. Compared to other enzymes, trypsin significantly increased the polysaccharide yields, whereas the protein content of polysaccharides extracted with trypsin was the lowest. Monosaccharide mainly includes glucose (> 50%) and mannose (> 10%). 1,1-Diphenyl-2-picrylhydrazyl radical scavenging activity, chelating activity, total antioxidant capacity and hydroxyl radical scavenging activity of Lanzhou lily polysaccharides extracted with trypsin were stronger than those extracted without enzymes (control). Structural characteristics of Lanzhou lily polysaccharides extracted with trypsin and extracted without enzymes were characterized by scanning electron microscopy and nuclear magnetic resonance spectroscopy. When water extracted polysaccharide and trypsin extracted polysaccharide concentrations were 200 µg mL-1 , Raw264.7 proliferation rates were 101.69% and 159.41%, respectively. CONCLUSION: The Lanzhou lily polysaccharide was identified as α-(1 → 6)-d-glucan. Consequently, the effects of both potential antioxidant and proliferative activity of trypsin are significant. © 2020 Society of Chemical Industry.

Structure and physicochemical properties of native starch and resistant starch in Chinese yam (Dioscorea opposita Thunb.).

The physicochemical properties of starch in Chinese yam (Dioscorea opposita Thunb.) are highly dependent on the growth stage. However, relevant information available is limited. In this work, native starch and resistant starch (RS) were prepared from Chinese yam tuber at expansion stage and dormant stage, respectively. Their structural and physicochemical properties were determined. They presented A-type polymorphic structure. The starches from dormant stage had smaller granule sizes, lower amylose contents, less branching degrees of amylopectin, and higher proportions of double helix than those from expansion stage. Dormant stage induced starch to form a more compact structure with a higher crystallinity and larger amount of short-range ordering than expansion stage. Moreover, the starch paste from dormant stage had a high thermal stability. These results were helpful for further application of Chinese yam starch in food products.

The antioxidant activity and neuroprotective mechanism of isoliquiritigenin.

Glycyrrhizae radix has been widely accepted as a functional food in Asia. Isoliquiritigenin is a characteristic bioactive chemical in this medicinal plant. In this work, the neuroprotective effect of isoliquiritigenin and the possible mechanisms were investigated. The results revealed that isoliquiritigenin exhibited better neuroprotective and antioxidant activities than quercetin, a commercial natural antioxidant. Isoliquiritigenin significantly inhibited the release of lactate dehydrogenase, and the generation of reactive oxygen species in H2O2-treated cells. The activities of superoxide dismutase, glutathione peroxidase and catalase were improved. The mRNA expression levels related to oxidative defense and cell apoptosis were reversed by isoliquiritigenin. Moreover, isoliquiritigenin might inhibit the cell apoptosis via ameliorating the loss of mitochondrial membrane potential and the change of nucleus morphology.

Identification of two novel prenylated flavonoids in mulberry leaf and their bioactivities.

Mulberry leaf is a vegetable used in daily diet. It can bring delicious taste and multiple health benefits. However, the chemicals responsible for these health benefits remain unveiled. In this work, two novel prenylated flavonoids were isolated from mulberry leaf. Their structures were identified and named as morachalcone D and morachalcone E. The protective effects of these two compounds were investigated, against endogenous oxidative damage (oxytosis/ferroptosis) induced by glutamate and erastin in HT22 cells. The results revealed that morachalcone D was much more potent in preventing from glutamate- and erastin-induced cell death than morachalcone E. The neuroprotective effect of morachalcone D was related to the prevention of ROS production, glutathione depletion, and iron accumulation. Morachalcone D upregulated the expression of genes involved in antioxidant defense, including GPx4, CAT, SOD2, Nrf2, HMOX1 and SLC7A11. These findings indicated that morachalcone D was responsible for the health benefits of mulberry leaf, and could be a potent neuroprotective agent for use in dietary supplements and functional foods.

Modification of structural, physicochemical and digestive properties of normal maize starch by thermal treatment.

Thermal treatment is an effective technique to modify the physiochemical properties of starch. However, investigation on the effect of repeated dry-heat treatment (RDHT) on the starch properties is limited. In this work, RDHT and continuous dry-heat treatment (CDHT) were conducted on normal maize starch. Both treatments increased pore no on the granule surface and facilitated the granule aggregation. The solubility and swelling power of normal maize starch were improved. The levels of slowly digestible starch (SDS) and resistant starch (RS) + SDS were increased. The structural characteristics, including crystallinity and short-range order, were impaired. The peak viscosity and thermal properties (To, Tp, Tc and ΔH) of starch paste were decreased. When comparing of CDHT samples with the same treating time, RDHT samples showed a lower crystallinity, a weaker thermal stability, a higher paste viscosity and a lower resistance to amylase. These results were useful for industrial application of thermal treatment on starch.

Identification of moracin N in mulberry leaf and evaluation of antioxidant activity.

Mulberry leaf is a newly accepted vegetable for daily diet. It tastes good and has multiple health benefits, including antioxidant and anti-inflammatory activities. However, the chemicals responsible for these health benefits remain unveiled. Prenylated phenolics are characteristic bioactive compounds in mulberry leaf, which are recognized as good antioxidants. In this work, moracin N was purified from mulberry leaf. It showed better antioxidant activities than resveratrol. The EC50 value of cellular antioxidant activity was 24.92 µM, and the IC50 value against DPPH radical was 40.00 µM. The prenyl group rendered the molecule more membrane affinity which improved the bioavailability. The furan ring was critical for the antioxidant behaviour. The cell viability test revealed that moracin N had a good safety. These results pointed out that moracin N contributed to the antioxidant activity of mulberry leaf.