The novel angiotensin-I-converting enzyme inhibitory peptides from Scomber japonicus muscle protein hydrolysates: QSAR-based screening, molecular docking, kinetic and stability studies.

Food-derived angiotensin-converting enzyme-inhibitory (ACE-I) peptides have attracted extensive attention. Herein, the ACE-I peptides from Scomber japonicus muscle hydrolysates were screened, and their mechanisms of action and inhibition stability were explored. The quantitative structure-activity relationship (QSAR) model based on 5z-scale metrics was developed to rapidly screen for ACE-I peptides. Two novel potential ACE-I peptides (LTPFT, PLITT) were predicted through this model coupled with in silico screening, of which PLITT had the highest activity (IC50: 48.73 ± 7.59 µM). PLITT inhibited ACE activity with a mixture of non-competitive and competitive mechanisms, and this inhibition mainly contributed to the hydrogen bonding based on molecular docking study. PLITT is stable under high temperatures, pH, glucose, and NaCl. The zinc ions (Zn2+) and copper ions (Cu2+) enhanced ACE-I activity. The study suggests that the QSAR model is effective in rapidly screening for ACE-I inhibitors, and PLITT can be supplemented in foods to lower blood pressure.

Stability and gastrointestinal behavior of curcumin-loaded emulsion stabilized by multi-conformation soy proteins: Influence of oil volume fraction.

The aim of this work was to assess the potential of nanoemulsions stabilized by mixed soy protein with multi-conformation as curcumin carrier, and the influence of oil volume fraction on stability and gastrointestinal behavior of curcumin-loaded emulsion was investigated. Loading efficiency showed a slight increase with higher oil content, though the difference was not statistically significant. With the increase of oil, the viscosity (Pa‧s), thixotropy (area of hysteresis loop) and particle size of the emulsion increased, which facilitated the physical and chemical stability of curcumin-loaded emulsion. However, the free fatty acid release rate and bioaccessibility of curcumin was negatively correlated with the oil volume fraction and the particle size of emulsion after gastric digestion. Notably, the digestion in stomach did not affect the structure of interfacial protein, demonstrating that protein-based nanoemulsions exhibited resistance to gastric digestion. This study provides theoretical guidance for the application of protein-based emulsion in curcumin delivery.

CYCLOIDEA-like genes control floral symmetry, floral orientation, and nectar guide patterning.

Actinomorphic flowers usually orient vertically (relative to the horizon) and possess symmetric nectar guides, while zygomorphic flowers often face horizontally and have asymmetric nectar guides, indicating that floral symmetry, floral orientation, and nectar guide patterning are correlated. The origin of floral zygomorphy is dependent on the dorsoventrally asymmetric expression of CYCLOIDEA (CYC)-like genes. However, how horizontal orientation and asymmetric nectar guides are achieved remains poorly understood. Here, we selected Chirita pumila (Gesneriaceae) as a model plant to explore the molecular bases for these traits. By analyzing gene expression patterns, protein-DNA and protein-protein interactions, and encoded protein functions, we identified multiple roles and functional divergence of 2 CYC-like genes, i.e. CpCYC1 and CpCYC2, in controlling floral symmetry, floral orientation, and nectar guide patterning. CpCYC1 positively regulates its own expression, whereas CpCYC2 does not regulate itself. In addition, CpCYC2 upregulates CpCYC1, while CpCYC1 downregulates CpCYC2. This asymmetric auto-regulation and cross-regulation mechanism might explain the high expression levels of only 1 of these genes. We show that CpCYC1 and CpCYC2 determine asymmetric nectar guide formation, likely by directly repressing the flavonoid synthesis-related gene CpF3'5'H. We further suggest that CYC-like genes play multiple conserved roles in Gesneriaceae. These findings shed light on the repeated origins of zygomorphic flowers in angiosperms.

Alkali-Induced Phenolic Acid Oxidation Enhanced Gelation of Ginkgo Seed Protein.

The effect of alkali-induced oxidation of three phenolic acids, namely gallic acid, epigallocatechin gallate, and tannic acid, on the structure and gelation of ginkgo seed protein isolate (GSPI) was investigated. A mixture of 12% (w/v) GSPI and different concentrations of alkali-treated phenolic acids (0, 0.06, 0.24, and 0.48% w/w) were heated at 90 °C, pH 6.0, for 30 min to form composite gels. The phenolic treatment decreased the hydrophobicity of the GSPI sol while enhancing their rheological properties. Despite a reduced protein solubility, water holding capacity, stiffness, and viscoelasticity of the gels were improved by the treatments. Among them, the modification effect of 0.24% (w/v) EGCG was the most prominent. Through the analysis of microstructure and composition, it was found to be due to the covalent addition, disulfide bond formation, etc., between the quinone derivatives of phenolic acids and the side chains of nucleophilic amino acids. Phenolic acid modification of GSPI may be a potential ingredient strategy in its processing.

Enhanced gelling properties and hydration capacity of ginkgo seed proteins by genipin cross-linking.

The present study investigated the effects of genipin cross-linking on the gelling properties of ginkgo seed protein isolate (GSPI). Cross-linking of GSPI was achieved with different concentrations (0, 0.05, 0.1, 0.2, 0.4, 0.6% w/v) of genipin at pH 6.0. Compared to pure GSPI, genipin treatment led to lower solubility, surface hydrophobicity, and fluorescence intensity, while promoted protein aggregation. Cross-linked GSPI gels exhibited markedly improved gelling properties and water holding capacity (WHC), with up to 2.1-fold increases in gel hardness and 1.3-fold increases in WHC over non-treated GSPI gel. Electrophoresis and Fourier-transform infrared spectroscopy confirmed the cross-linking. Moreover, microstructural examination showed that cross-linking with genipin resulted in protein aggregation and more porous gel matrix. Overall, genipin cross-linking demonstrated great potential for the enhancement of gelling properties of ginkgo seed protein. The current research may expand the utilization of ginkgo seeds in food applications.

Characterization, Stability, and Antibrowning Effects of Oxyresveratrol Cyclodextrin Complexes Combined Use of Hydroxypropyl Methylcellulose.

Oxyresveratrol (Oxy) has attracted much attention by employing it as an antibrowning agent in fruits and vegetables. In this study, the formation of cyclodextrin (CD) inclusion exhibited a certain protective effect on Oxy oxidative degradation, while hydroxypropyl-ß-cyclodextrin (HP-ß-CD) inclusion complex showed stronger stabilizing effects than those of ß-cyclodextrin (ß-CD). The combined use of CD and hydroxypropyl methylcellulose (HPMC) greatly improved the stability of Oxy-CD inclusion complexes, with approximately 70% of the trans-Oxy retained after 30 days of storage under light conditions at 25 °C. The results of the interaction between CD and Oxy determined by phase solubility studies and fluorescence spectroscopic analysis showed that the binding strength of CD and Oxy increased in the presence of HPMC. Moreover, Oxy combined with ascorbic acid and HPMC showed an excellent antibrowning effect on fresh-cut apple slices during the 48 h test period, indicating that adding HPMC as the third component will not influence the antibrowning activity of Oxy.

Comparative Effectiveness of Robot-Assisted Training Versus Enhanced Upper Extremity Therapy on Upper and Lower Extremity for Stroke Survivors: A Multicentre Randomized Controlled Trial.

OBJECTIVE: Robot-assisted neuro-rehabilitation therapy plays a central role in upper extremity recovery of stroke. However, the efficacy of robotic training on the upper extremity is not yet well defined, and little attention has been devoted to its potential effect on the lower extremity. The aim of this study was to compare the efficacy of robot-assisted training and therapist-mediated enhanced upper extremity therapy on the upper and lower extremities. METHODS: A randomized clinical trial involving 172 stroke survivors was conducted in China. All participants received either robot-assisted training or enhanced upper extremity therapy for 3 weeks. Fugl-Meyer assessment upper extremity subscale (FMA-UE), Fugl-Meyer assessment lower extremity subscale (FMA-LE), and Modified Barthel Index were administered at baseline, mid-treatment (1 week after treatment start), and post-treatment. RESULTS: Participants in the robot-assisted training group showed a significant improvement in the hemiplegia extremity, which was non-inferior to the enhanced upper extremity therapy group in FMA-UE (p < 0.05), while suggesting greater motor recovery of lower extremity in FMA-LE (p < 0.05) compared with the enhanced upper extremity therapy group. A marked increase in Modified Barthel Index was observed within groups; however, no significant difference was found between groups. CONCLUSION: Robot-assisted training is non-inferior but not better in reducing impairment of the upper extremity and appears to be superior in reducing impairment of the lower extremity compared with enhanced upper extremity therapy for stroke survivors.

Enzymatic hydrolysates of soy protein promote the physicochemical stability of mulberry anthocyanin extracts in food processing.

Soy protein papain hydrolysate (SPAH) and soy protein pepsin hydrolysate (SPEH) were used as protective agents for mulberry anthocyanin extracts (MAEs) to inhibit its color fading and enhance the anthocyanin stability at pH 6.3. Both SPAH and SPEH showed a significant protective effect on total anthocyanins in MAEs solutions. 1.0 mg/mL of SPEH presented the best protective effect on MAEs by increasing its half-life from 1.8 to 5.7 days. SPAH/SPEH-cyaniding-3-O-glucoside (C3G) interactions were investigated at pH 6.3 by fluorescence, Fourier-transform infrared spectroscopy (FT-IR), and Circular Dichroism (CD). Their association was mainly driven by hydrophobic interactions, and SPEH showed a higher binding affinity for C3G than SPAH, with a KA value of 2.62 × 105 M-1 at 300 K. The second structures of SPAH and SPEH were altered by C3G, with a decrease in the ß-sheets and an increase in the turns and random coils.

The immune-enhancing effect and in vitro antioxidant ability of different fractions separated from Colla corii asini.

In this study, Colla corii asini (CCA) was fractionated into three fractions with different molecular weights using ultracentrifugation equipment. Components with a molecular weight of >10 kDa in F1 accounted for 81.90%, whereas that in F2 and F3 was 15.63% and 0.94%, respectively. The immunomodulatory activity of CCA fractions was investigated using RAW264.7 cell model and their antioxidant abilities were evaluated by 2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) and ferric-reducing antioxidant power (FRAP) assay. The results indicated that RAW264.7 cells treated with F1 released the highest level of nitric oxide, reactive oxygen species, interleukin-6, and tumor necrosis factor-α. The ABTS and FRAP value of F1 were 65.81% and 29.33 µM TE/L, respectively, which were 22.53%, 128.44% and 43.72%, 132.16% higher than that of F2 and F3, respectively. These results suggested that components with a molecular weight of >10 kDa in CCA had stronger immunomodulatory and antioxidant ability, which would help develop the health food based on CCA. PRACTICAL APPLICATIONS: Colla corii asini (CCA) is a famous protein-based traditional Chinese medicine and nutritional supplement. During the processing of CCA, the molecular weight (MW) of CCA collagen components changed dynamically due to the protein aggregation, degradation, and the Maillard reaction. Some studies have shown that the MW distribution of CCA was not uniform. However, the MW range of CCA components which has strong antioxidant and immunomodulatory activity is still not clear, and few studies have reported the mechanism of CCA's immunomodulatory activity and active ingredients. Therefore, it is important to figure out the characteristics of CCA components with stronger immunomodulatory and antioxidant ability, such as the MW distribution and chemical composition of CCA fractions. And this study will be great for the processing of CCA products which has better biological functions.

The Effect of Applying Robot-Assisted Task-Oriented Training Using Human-Robot Collaborative Interaction Force Control Technology on Upper Limb Function in Stroke Patients: Preliminary Findings.

Stroke is one of the leading causes of death and the primary cause of acquired disability worldwide. Many stroke survivors have difficulty using their upper limbs, which have important functional roles in the performance of daily life activities. Consequently, the independence and quality of life of most stroke patients are reduced. Robot-assisted therapy is an effective intervention for improving the upper limb function of individuals with stroke. Human-robot collaborative interaction force control technology is critical for improving the flexibility and followability of the robot's motion, thereby improving rehabilitation training outcomes. However, there are few reports on the effect of robot-assisted rehabilitative training on upper limb function. We applied this technology using a robot to assist patients with task-oriented training. Posttreatment changes in Fugl-Meyer and modified Barthel index (MBI) scores were assessed to determine whether this technology could improve the upper limb function of stroke patients. One healthy adult and five stroke patients, respectively, participated in functional and clinical experiments. The MBI and Fugl-Meyer scores of the five patients in the clinical experiments showed significant improvements after the intervention. The experimental results indicate that human-robot collaborative interaction force control technology is valuable for improving robots' properties and patients' recovery. This trial was registered in the Chinese clinical trial registry (ChiCTR2000038676).

Customizing Robot-Assisted Passive Neurorehabilitation Exercise Based on Teaching Training Mechanism.

Passive movement is an important mean of rehabilitation for stroke survivors in the early stage or with greater paralysis. The upper extremity robot is required to assist therapists with passive movement during clinical rehabilitation, while customizing is one of the crucial issues for robot-assisted upper extremity training, which fits the patient-centeredness. Robot-assisted teaching training could address the need well. However, the existing control strategies of teaching training are usually commanded by position merely, having trouble to achieve the efficacy of treatment by therapists. And deficiency of flexibility and compliance comes to the training trajectory. This research presents a novel motion control strategy for customized robot-assisted passive neurorehabilitation. The teaching training mechanism is developed to coordinate the movement of the shoulder and elbow, ensuring the training trajectory correspondence with human kinematics. Furthermore, the motion trajectory is adjusted by arm strength to realize dexterity and flexibility. Meanwhile, the torque sensor employed in the human-robot interactive system identifies movement intention of human. The goal-directed games and feedbacks promote the motor positivity of stroke survivors. In addition, functional experiments and clinical experiments are investigated with a healthy adult and five recruited stroke survivors, respectively. The experimental results present that the suggested control strategy not only serves with safety training but also presents rehabilitation efficacy.

Storage stability of soy protein isolate powders containing soluble protein aggregates formed at varying pH.

Soy protein is wildly used in food industry due to its high nutritional value and good functionalities. However, the poor storage stability of commercial soy protein products has puzzled both the producers and the users for a long time. The current study assessed the changes in protein solubility, aggregation, oxidation, and conformation of soy protein isolate (SPI) with various soluble aggregates formed at different pH values (pH 5-8) during storage. During storage, SPI samples showed a reduced protein solubility (p < .05), an increased protein oxidation (p < .05), and an attenuated conformational enthalpy (∆H). SPI with a higher pH produced more disulfide-mediated aggregates at the expense of sulfhydryl groups and experienced greater losses of protein tertiary structure and a faster reduction in solubility. Yet, all samples nearly shared similar rising trend during 8-week storage, which indicated the production of protein carbonyls was insensitive to pH. Soluble aggregates present in fresh SPI samples appeared to induce instability of SPI during storage. These findings suggested SPI prepared at pH 6 was in favor of its storage stability, and soluble aggregates presented in fresh samples should be paid more attention for further study of storage stability kinetics.

Encapsulation Mechanism of Oxyresveratrol by ß-Cyclodextrin and Hydroxypropyl-ß-Cyclodextrin and Computational Analysis.

In this study, the encapsulation mechanism of oxyresveratrol and ß-cyclodextrin (ß-CD) and hydroxypropyl-ß-cyclodextrin (HP-ß-CD) was studied. As this research shows, oxyresveratrol and two cyclodextrins (CDs) were able to form inclusion complexes in a 1:1 stoichiometry. However, the interaction with HP-ß-CD was more efficient, showing up as higher encapsulation constant (KF) (35,864.72 ± 3415.89 M-1). The KF values exhibited a strong dependence on temperature and pH, which decreased as they increased. From the thermodynamic parameters (ΔH°, ΔS°, and ΔG°) of the oxyresveratrol loaded ß-CD (oxyresveratrol-ß-CD) and HP-ß-CD (oxyresveratrol-HP-ß-CD), it could be seen that the complexation process was spontaneous and exothermic, and the main driving forces between oxyrsveratrol and CDs were hydrogen bonding and van der waals force. Besides, molecular docking combined with ¹H-NMR were used to explain the most possible mode of interactions between oxyresveratrol and CDs.

Inhibitory profiles of spices against free and protein-bound heterocyclic amines of roast beef patties as revealed by ultra-performance liquid chromatography-tandem mass spectrometry and principal component analysis.

The effects of various levels of chili pepper, Sichuan pepper, and black pepper on the amounts of 17 heterocyclic amines (HAs) from seven categories of both free and protein-bound states in roast beef patties were assessed by ultra-performance liquid chromatography-tandem mass spectrometry combined with principal component analysis. Three groups of HA, including imidazopyridines (DMIP), imidazoquinoxalines (MeIQx and 4,8-MeIQx), and ß-carbolines (norharman and harman), were detected and quantified in both their free and protein-bound states, whereas PhIP was detected only in its free state, and imidazoquinolines (IQ, IQ[4,5-b], and MeIQ), α-carbolines (AαC and MeAαC), and phenylpyridines (Phe-P-1) were detected only in their protein-bound states. The results demonstrate that the peppers at all three levels had significant inhibitory effects on free PhIP, DMIP, MeIQx, and 4,8-DiMeIQx and could promote free norharman. Harman was significantly suppressed by chili pepper and black pepper, but enhanced by Sichuan pepper. All 11 protein-bound HAs, with the exception of IQ, IQ[4,5-b], and MeIQx with added chili pepper, were significantly reduced by the three peppers. The total amounts of the free and protein-bound states of all 11 HAs (1692.4 ± 78.9 ng g-1), imidazopyridines (5.5 ± 0.2 ng g-1), imidazoquinolines (7.2 ± 0.2 ng g-1), imidazoquinoxalines (6.9 ± 0.2 ng g-1), α-carbolines (20.1 ± 0.4 ng g-1), and ß-carbolines (1651.7 ± 79.5 ng g-1) were suppressed by each level of all of the three peppers except for 0.5% and 1.0% chili pepper. Our findings may facilitate the inhibition of HA formation in the processing of meat products.

Deep sequencing and transcriptome analyses to identify genes involved in secoiridoid biosynthesis in the Tibetan medicinal plant Swertia mussotii.

Swertia mussotii Franch. is an important traditional Tibetan medicinal plant with pharmacological properties effective in the treatment of various ailments including hepatitis. Secoiridoids are the major bioactive compounds in S. mussotii. To better understand the secoiridoid biosynthesis pathway, we generated transcriptome sequences from the root, leaf, stem, and flower tissues, and performed de novo sequence assembly, yielding 98,613 unique transcripts with an N50 of 1,085 bp. Putative functions could be assigned to 35,029 transcripts (35.52%) based on BLAST searches against annotation databases including GO and KEGG. The expression profiles of 39 candidate transcripts encoding the key enzymes for secoiridoid biosynthesis were examined in different S. mussotii tissues, validated by qRT-PCR, and compared with the homologous genes from S. japonica, a species in the same family, unveiling the gene expression, regulation, and conservation of the pathway. The examination of the accumulated levels of three bioactive compounds, sweroside, swertiamarin, and gentiopicroside, revealed their considerable variations in different tissues, with no significant correlation with the expression profiles of key genes in the pathway, suggesting complex biological behaviours in the coordination of metabolite biosynthesis and accumulation. The genomic dataset and analyses presented here lay the foundation for further research on this important medicinal plant.

Surface properties of heat-induced soluble soy protein aggregates of different molecular masses.

Suspensions (2% and 5%, w/v) of soy protein isolate (SPI) were heated at 80, 90, or 100 °C for different time periods to produce soluble aggregates of different molecular sizes to investigate the relationship between particle size and surface properties (emulsions and foams). Soluble aggregates generated in these model systems were characterized by gel permeation chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Heat treatment increased surface hydrophobicity, induced SPI aggregation via hydrophobic interaction and disulfide bonds, and formed soluble aggregates of different sizes. Heating of 5% SPI always promoted large-size aggregate (LA; >1000 kDa) formation irrespective of temperature, whereas the aggregate size distribution in 2% SPI was temperature dependent: the LA fraction progressively rose with temperature (80→90→100 °C), corresponding to the attenuation of medium-size aggregates (MA; 670 to 1000 kDa) initially abundant at 80 °C. Heated SPI with abundant LA (>50%) promoted foam stability. LA also exhibited excellent emulsifying activity and stabilized emulsions by promoting the formation of small oil droplets covered with a thick interfacial protein layer. However, despite a similar influence on emulsion stability, MA enhanced foaming capacity but were less capable of stabilizing emulsions than LA. The functionality variation between heated SPI samples is clearly related to the distribution of aggregates that differ in molecular size and surface activity. The findings may encourage further research to develop functional SPI aggregates for various commercial applications.