Content Of Aromatic Amino Acids Research Articles

Metabolomics analysis of splenectomy of Nile tilapia (Oreochromis niloticus) reveals the spleen involved in regulating liver lipids and amino acids metabolism

The liver is essential for nutritional balance in fish, and liver damage in farmed fish often arises from factors like overfeeding, causing various health issues. Clinical observations indicate that liver diseases frequently involve spleen dysfunction, and there is evidence to suggest that the spleen has a significant impact on liver function. However, there has been no discussion on the role of the spleen in maintaining liver health in fish. To understand the role of fish spleen in liver metabolism, this study selected Nile tilapia (Oreochromis niloticus) as the experimental material and first established a tilapia splenectomy model. Various biochemical parameters of the liver and serum were measured, and the liver metabolism characteristics of the splenectomy group (SP group) and the sham operation group (SO group) were analyzed using metabolomics. After splenectomy, biochemical parameters of the liver and serum showed abnormalities, including significant increases in total cholesterol (T-CHO) and serum total bile acid (TBA) levels, alongside a significant decrease in liver TBA levels, suggesting impaired metabolic function and cholesterol deposition in the liver. Metabolomics analysis showed that metabolites such as lipids, lipid-like molecules, and organic acids and derivatives were differentially regulated between the SO and SP group. KEGG analysis showed that differential metabolites were enriched in lipid metabolism and amino acid metabolism. The metabolic pathway analysis of differential metabolites showed that after splenectomy, the low-activity urea cycle in the liver may accelerate lipid synthesis, while low concentrations of aromatic amino acids and taurine may inhibit lipid catabolism. These results indicate that after splenectomy, the liver metabolic capacity is impaired, which causes abnormal lipid metabolism by interfering with amino acid metabolism, making splenectomy tilapia liver at risk of liver disease, including cholesterol deposition, hepatic steatosis and nonalcoholic fatty liver disease (NAFLD). Our results show that the spleen is involved in regulating liver lipid and amino acid metabolism, and the spleen may interfere with lipid metabolism by regulating liver amino acid metabolism. Our data can provide support for further research on liver and spleen functions and the immune-nutrient metabolism mechanisms in fish, as well as new ideas for healthy fish farming.

Antioxidant polypeptides derived from pigeon pea (Cajanus cajan (L) Mill sp.) by enzymatic hydrolysis

Pigeon pea (Cajanus cajan (L) Mill sp.) seeds are rich sources of protein in the legume family and their consumption has been associated with the prevention of noncommunicated diseases, which is attributable to their content of bioactive components. Antioxidant protein hydrolysates were produced from pigeon pea protein isolate (PPI) by enzymatic hydrolysis using pancreatin and flavourzyme. The hydrolysates were analyzed for their physicochemical, molecular weight, amino acid composition, and in vitro antioxidant activities. The molecular weights of polypeptides in the hydrolysates were 8, 20, 25 and 48 kDa, which were determined after pancreatin or flavourzyme hydrolysis of the protein isolate for 4 h. Pancreatin-hydrolyzed pigeon pea protein (PPHP) contained high hydrophobic amino acids, especially isoleucine, leucine and valine, which were related to the high content of aromatic amino acids. The hydrolysates obtained from flavourzyme hydrolysis of pigeon pea proteins (PPHF) presented significantly higher capacities to scavenge ABTS˙+ and reduce Fe3 + better than that of PPI, while the PPI exhibited strong DPPH scavenging (98.4 mg trolox equivalent antioxidant capacity). The results indicated that the partial hydrolysis for PPI provided medium to high molecular weight of peptides. Therefore, PPHF could be a promising source of bioactive peptides and a potential ingredient for the formulation of functional foods against oxidative stress

CRISPR/Cas9-mediated homology donor repair base editing system to confer herbicide resistance in maize (Zea mays L.)

Weed infestation is a significant concern to crop yield loss, globally. The potent broad-spectrum glyphosate (N-phosphomethyl-glycine) has a widely utilized herbicide, acting on the shikimic acid pathway within chloroplast by inhibiting 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). This crucial enzyme plays a vital role in aromatic amino acid synthesis. Repurposing of CRISPR/Cas9-mediated gene-editing was the inflection point for generating novel crop germplasm with diverse genetic variations in essential agronomic traits, achieved through the introduction of nucleotide substitutions at target sites within the native genes, and subsequent induction of indels through error-prone non-homologous end-joining DNA repair mechanisms. Here, we describe the development of efficient herbicide-resistant maize lines by using CRISPR/Cas9 mediated site-specific native ZmEPSPS gene fragment replacement via knock-out of conserved region followed by knock-in of desired homologous donor repair (HDR-GATIPS-mZmEPSPS) with triple amino acid substitution. The novel triple substitution conferred high herbicide tolerance in edited maize plants. Transgene-free progeny harbouring the triple amino acid substitutions revealed agronomic performances similar to that of wild-type plants, suggesting that the GATIPS-mZmEPSPS allele substitutions are crucial for developing elite maize varieties with significantly enhanced glyphosate resistance. Furthermore, the aromatic amino acid contents in edited maize lines were significantly higher than in wild-type plants. The present study describing the introduction of site-specific CRISPR/Cas9- GATIPS mutations in the ZmEPSPS gene via genome editing has immense potential for higher tolerance to glyphosate with no yield penalty in maize.

Short-Term Metabolic Changes and Their Physiological Mediators in the Roux-en-Y Gastric Bypass Bariatric Surgery

BackgroundThe Roux-en-Y gastric bypass (RYGB) is a common bariatric surgery to treat obesity. Its metabolic consequences are favourable and long-term clinical corollaries beneficial. However, detailed assessments of various affected metabolic pathways and their mediating physiological factors are scarce.MethodsWe performed a clinical study with 30 RYGB patients in preoperative and 6-month postoperative visits. NMR metabolomics was applied to profiling of systemic metabolism via 80 molecular traits, representing core cardiometabolic pathways. Glucose, glycated haemoglobin (HbA1c), insulin, and apolipoprotein B-48 were measured with standard assays. Logistic regression models of the surgery effect were used for each metabolic measure and assessed individually for multiple mediating physiological factors.ResultsChanges in insulin concentrations reflected those of BMI with robust decreases due to the surgery. Six months after the surgery, triglycerides, remnant cholesterol, and apolipoprotein B-100 were decreased −24%, −18%, and −14%, respectively. Lactate and glycoprotein acetyls, a systemic inflammation biomarker, decreased −16% and −9%, respectively. The concentrations of branched-chain (BCAA; leucine, isoleucine, and valine) and aromatic (phenylalanine and tyrosine) amino acids decreased after the surgery between −17% for tyrosine and −23% for leucine. Except for the most prominent metabolic changes observed for the BCAAs, all changes were almost completely mediated by weight change and insulin. Glucose and type 2 diabetes had clearly weaker effects on the metabolic changes.ConclusionsThe comprehensive metabolic analyses indicate that weight loss and improved insulin sensitivity during the 6 months after the RYGB surgery are the key physiological outcomes mediating the short-term advantageous metabolic effects of RYGB.The clinical study was registered at ClinicalTrials.gov as NCT01330251.Graphical

The Nutritional and Functional Properties of Protein Isolates from Defatted Chia Flour Using Different Extraction pH.

This study aims to determine the effects of various alkaline pHs on the nutritional and functional properties of protein isolated from defatted chia flour (DCF). The DCF isolated using alkali extraction method at pH 8.5, 10.0, and 12.0 were coded as CPI-8.5, CPI-10.0, and CPI-12.0, respectively. The highest extraction yield and protein recovery yield was demonstrated by CPI-12.0 (19.10 and 59.63%, respectively), with a total protein content of 74.53%, and glutelin showed the highest portion (79.95%). The CPI-12.0 also demonstrated the most elevated essential (36.87%), hydrophobic (33.81%), and aromatic (15.54%) amino acid content among other samples. The DCF exhibited the highest water (23.90 gg-1) and oil (8.23 gg-1) absorption capacity, whereas the CPI-8.5 showed the highest protein solubility (72.31%) at pH 11. DCF demonstrated the highest emulsifying capacity at pH 11 (82.13%), but the highest stability was shown at pH 5 (82.05%). Furthermore, CPI-12.0 at pH 11 shows the highest foaming capacity (83.16%) and stability (83.10%). Despite that, the CPI-10.0 manifested the highest antioxidant capacity (DPPH: 42.48%; ABTS: 66.23%; FRAP: 0.19), as well as ACE-I (35.67%). Overall, the extraction pH had significant effects in producing chia protein isolates (CPI) with improved nutritional and functional qualities.

CRISPR/Cas9-mediated homology donor repair base editing confers glyphosate resistance to rice (Oryza sativa L.).

Globally, CRISPR-Cas9-based genome editing has ushered in a novel era of crop advancements. Weeds pose serious a threat to rice crop productivity. Among the numerous herbicides, glyphosate [N-(phosphonomethyl)-glycine] has been employed as a post-emergent, broad-spectrum herbicide that represses the shikimate pathway via inhibition of EPSPS (5'-enolpyruvylshikimate-3-phosphate synthase) enzyme in chloroplasts. Here, we describe the development of glyphosate-resistant rice lines by site-specific amino acid substitutions (G172A, T173I, and P177S: GATIPS-mOsEPSPS) and modification of phosphoenolpyruvate-binding site in the native OsEPSPS gene employing fragment knockout and knock-in of homology donor repair (HDR) template harboring desired mutations through CRISPR-Cas9-based genome editing. The indigenously designed two-sgRNA OsEPSPS-NICTK-1_pCRISPR-Cas9 construct harboring rice codon-optimized SpCas9 along with OsEPSPS-HDR template was transformed into rice. Stable homozygous T2 edited rice lines revealed significantly high degree of glyphosate-resistance both in vitro (4 mM/L) and field conditions (6 ml/L; Roundup Ready) in contrast to wild type (WT). Edited T2 rice lines (ER1-6) with enhanced glyphosate resistance revealed lower levels of endogenous shikimate (14.5-fold) in contrast to treated WT but quite similar to WT. ER1-6 lines exhibited increased aromatic amino acid contents (Phe, two-fold; Trp, 2.5-fold; and Tyr, two-fold) than WT. Interestingly, glyphosate-resistant Cas9-free EL1-6 rice lines displayed a significant increment in grain yield (20%-22%) in comparison to WT. Together, results highlighted that the efficacy of GATIPS mutations in OsEPSPS has tremendously contributed in glyphosate resistance (foliar spray of 6 ml/L), enhanced aromatic amino acids, and improved grain yields in rice. These results ensure a novel strategy for weed management without yield penalties, with a higher probability of commercial release.

Effects of molecular weight fraction on antioxidation capacity of rice protein hydrolysates

Rice protein was used as a starting material to provide rice protein hydrolysates (RPH) through enzyme-assisted extraction. RPH was further fractionated using ultrafiltration membrane (UF) and classified by molecular weight (MW; MW < 1 kDa, MW 1–10 kDa, and MW > 10 kDa). Peptides with MW < 1 kDa possessed superior antioxidant properties (p < 0.05). Therefore, UF demonstrated great efficacy in selectively separating antioxidant peptides. A Pearson correlation analysis revealed that the total phenolic concentration was correlated with oxygen radical absorbance capacity (ORAC; r = 0.999, p < 0.05). Amino acid contents had negative correlations with the scavenging activity (specifically, IC50) of 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radicals (r = − 0.986 to − 1.000). Reducing power was related to aromatic amino acid contents (r = 0.997, p < 0.05). In this study, enzymatic hydrolysis was discovered to be an effective method of extracting and isolating natural antioxidant proteins from broken rice, thus preserving the nutritional quality of rice and making those proteins more accessible in future applications.

Plasma Branched-Chain Amino Acid Concentrations and Glucose Homeostasis in Kidney Transplant Recipients and Candidates

Post-transplant diabetes mellitus (PTDM) encompasses new-onset and previously unrecognized type 2 diabetes. Kidney failure masks type 2 diabetes. Branched-chain amino acids (BCAA) are closely associated with glucose metabolism. Therefore, understanding BCAA metabolism both in kidney failure and after kidney transplantation may inform PTDM mechanisms. To understand the impact of present or absent kidney function on plasma BCAA concentrations. Cross-sectional study of kidney transplant recipients and kidney transplant candidates. Large kidney transplant center in Toronto, Canada. We measured plasma BCAA and aromatic amino acid (AAA) concentrations in 45 pre-kidney transplant candidates (15 with type 2 diabetes, 30 without type 2 diabetes) and 45 post-kidney transplant recipients (15 PTDM, 30 non-PTDM), along with insulin resistance and sensitivity by 75 g oral glucose loading for those in each group without type 2 diabetes. Plasma AA concentrations were analyzed using MassChrom AA Analysis and compared between groups. The insulin sensitivity for oral glucose tolerance tests or Matsuda index (a measure of whole-body insulin resistance), Homeostatic Model Assessment for Insulin Resistance (a measure of hepatic insulin resistance), and Insulin Secretion-Sensitivity Index-2 (ISSI-2, a measure of pancreatic β-cell response) was calculated from fasting insulin and glucose concentrations, and compared with BCAA concentrations. Each BCAA concentration was higher in post-transplant subjects than pre-transplant subjects (P < .001 for leucine, isoleucine, valine). In post-transplant subjects, each BCAA concentration was higher in PTDM versus non-PTDM (odds ratio for PTDM 3-4 per 1 SD increase in BCAA concentration, P < .001 for each). Tyrosine concentrations were also higher in post-transplant subjects than pre-transplant subjects, but tyrosine did not differ by PTDM status. By contrast, neither BCAA nor AAA concentrations were different in pre-transplant subjects with or without type 2 diabetes. Whole-body insulin resistance, hepatic insulin resistance, and pancreatic β-cell response did not differ between nondiabetic post-transplant and pre-transplant subjects. Branched-chain amino acid concentrations correlated with the Matsuda index and Homeostatic Model Assessment for Insulin Resistance (P < .05 for each) only in nondiabetic post-transplant subjects-not in nondiabetic pre-transplant subjects. Branched-chain amino acid concentrations did not correlate with ISSI-2 in either pre-transplant or post-transplant subjects. The sample size was small, and subjects were not studied prospectively for the development of type 2 diabetes. Plasma BCAA concentrations are higher post-transplant in type 2 diabetic states, but do not differ by diabetes status in the presence of kidney failure. The association of BCAA with measures of hepatic insulin resistance among nondiabetic post-transplant patients is consistent with impaired BCAA metabolism as a characteristic of kidney transplantation.

Influence of Enzymatic Hydrolysis and Molecular Weight Fractionation on the Antioxidant and Lipase / α-Amylase Inhibitory Activities In Vitro of Watermelon Seed Protein Hydrolysates.

This study aims to evaluate the potential in vitro antioxidant and anti-obesity activities of watermelon seed protein hydrolysates (WSPH) obtained using different combinations of enzymes alcalase-proteinase K (ALC-PK) and alcalase-actinidin (ALC-ACT). There was a direct relationship between the degree of hydrolysis (DH) and the biological activities of the WSPH, with the highest DPPH (approximately 85%) and lipase inhibitory activities (≈59%) appreciated at DH of 36-37% and 33-35% when using ALC-PK and ALC-ACT, respectively. Following molecular weight fractionation, the ALC-PK WSPH &lt; 3 kDa (F1) assayed at 1 mg.mL-1 had the highest DPPH-radical scavenging (89.22%), ferrous chelating (FC) (79.83%), reducing power (RP) (A 0.51), lipase inhibitory (71.36%), and α-amylase inhibitory (62.08%) activities. The amino acid analysis of ALC-PK WSPH and its fractions revealed a relationship between the biological activity of the extracts and their composition. High contents of hydrophobic amino acids, arginine, and aromatic amino acids were related to high antioxidant, lipase inhibitory, and α-amylase inhibitory activities in the extracts, respectively. Overall, this study revealed that underutilized protein sources such as WSPH, using the appropriate combination of enzymes, could result in the generation of new ingredients and compounds with powerful antioxidant and anti-obesity activities with promising applications as nutraceuticals or functional foods.

The growth performance, antioxidative status and muscle quality of grass carp (Ctenopharyngodon idellus) cultured in the recirculating pond aquaculture system (RPAS)

The recirculating pond aquaculture system (RPAS) consisted of culture ponds, a purification pond, inflow ditch, outflow pipe, ecological ditch, and electrically driven pump. The performance of RPAS on grass carp (Ctenopharyngodon idellus) was explored in this study. In both the RPAS and the traditional pond aquaculture system (TPAS), water quality, fish growth performance, muscle quality, and tissue biochemical properties were assessed. Pond water was exchanged every seven days in RPAS and treated using a purification system that included an ecological ditch and a purification pond with a floating bed and aquatic plant. In RPAS, nitrate‑nitrogen, ammonia‑nitrogen, and nitrite‑nitrogen concentrations were lower than in TPAS. Fish cultured in RPAS exhibited significant higher growth rate and lower feed conversion rate. A significant increase in the expression of growth-related genes of myogenin (MyoG), myofactar-5 (Myf-5), insulin-like growth factor-I gene (igf-1), insulin-like growth factor-II gene (igf-2), and growth hormone receptor gene (ghr) were found in the fish cultured in the RPAS ponds. The content of malondialdehyde in either serum or liver and hepatic protein carbonyls content declined significantly in the RPAS ponds. The activities of T-SOD and GSH in liver and GSH in serum elevated significantly in RPAS fish. Muscular histological characteristics and texture profiles did not alter between two groups. The muscular contents of aromatic amino acids of aspartic acid and glutamic acid were significantly higher in RPAS than those in TPAS. It is inferred that RPAS is beneficial to promote fish growth, decrease oxidative stress, and increase muscle umami flavor.

Post-Harvest LED Light Irradiation Affects Firmness, Bioactive Substances, and Amino Acid Compositions in Chili Pepper (Capsicum annum L.).

Chili pepper is an important vegetable and spice crop with high post-harvest deteriorations in terms of commercial and nutritional quality. Light-emitting diodes (LEDs) are eco-friendly light sources with various light spectra that have been demonstrated to improve the shelf-life of various vegetables by manipulating light quality; however, little is known about their effects on the post-harvest nutritional quality of chili peppers. This study investigated the effects of different LED lightings on the post-harvest firmness and nutritional quality of chili peppers. We found that red and blue light could increase the content of capsaicinoids, whereas white and red light could increase the essential and aromatic amino acid (AA) content in pepper. Nonetheless, the influence of light treatments on AA contents and compositions depends strongly on the pepper genotype, which was reflected by total AA content, single AA content, essential AA ratio, delicious AA ratio, etc., that change under different light treatments. Additionally, light affected fruit firmness and the content of nutrients such as chlorophyll, vitamin C, and total carotenoids, to varying degrees, depending on pepper genotypes. Thus, our findings indicate that LED-light irradiation is an efficient and promising strategy for preserving or improving the post-harvest commercial and nutritional quality of pepper fruit.

Aromatic Amino Acids: Phenylalanine and Tyrosine in Patients with Hypertension and Coronary Artery Disease

Aim. To evaluate changes in the profile of aromatic amino acids (AAA) in patients with cardiovascular diseases (CVD): hypertension and coronary artery disease (CАD) in comparison with healthy study participants.Material and methods. One hundred and thirty-one participants were included in the study: 58 participants were included in the hypertension group, 46 in the CАD group, and 27 participants without signs of CVD in the control group. We used ultrahigh-performance liquid chromatography in combination with a triple quadrupole analyzer to measure plasma AAA: phenylalanine and tyrosine (Phe, Tyr) in all study participants. The association of AAA with biochemical blood test parameters, echocardiography (EchoCG) parameters, blood pressure level and clinical characteristics was analyzed.Results. A statistically significant difference in the level of concentration of Phe and Tyr was revealed (p=0,002 and p=0,024, respectively), comparing the three groups. Post-hoc analysis showed differences in the circulating level of both amino acids in patients with CAD vs the control group (Phe p=0,008 and Tyr p=0,020). Also a statistically significant difference in the level of Phe of the hypertension and CАD groups (p=0,017) was found. A negative correlation of low-density lipoproteins (LDL) with the level of Phe (r=-0,685, p&lt;0,05) and Tyr (r=-0,583, p&lt;0,05), as well as the level of Phe with total cholesterol (r=-0,461, p&lt;0,05) was found in the group without CVD. In the hypertension group, only a weak positive correlation was found between very low-density lipoproteins and AAA levels (Phe r=0,326 and Tyr r=0,365, p&lt;0,05), while in patients with CAD, the level of Phe and Tyr was negative correlated with high-density lipoprotein (r=-0,378 and r=-0,543, respectively, p&lt;0,05), and the level of Tyr with LDL (r=0,349, p&lt;0,05). When isolating the group with proven atherosclerosis of peripheral and/or coronary arteries, a statistically significant difference was revealed between the group of patients with CVD and clinical and instrumental signs of atherosclerosis and the group of patients with CVD without proven atherosclerosis in Phe level (p=0,019).Conclusion. Concentrations of AAA were higher in patients with CVD, comparing with the control group. At the same time, an increase of the Phe level was associated with the presence of peripheral or coronary atherosclerosis. The revealed correlations of AAA with EchoCG parameters and lipid spectrum parameters require further study to understand the involvement of AAA in pathogenesis of CVD and its potential role as treatment target.

Role of Signaling Molecules Sodium Nitroprusside and Arginine in Alleviating Salt-Induced Oxidative Stress in Wheat.

Nitric oxide (NO) is a well-accepted signaling molecule that has regulatory effects on plants under various stresses. Salinity is a major issue that adversely affects plant growth and productivity. The current study was carried out to investigate changes in the growth, biochemical parameters, and yield of wheat plants in response to NO donors, namely sodium nitroprusside (SNP) (2.5 and 5.0 mM) and arginine (10 and 20 mM), under two salinity levels (1.2 mM and 85.5 mM NaCl). Salinity stress significantly decreased the lengths and weights of plant parts (shoot, tiller, and root) and reduced the flag leaf area, photosynthetic pigments, indole acetic acid (IAA), and yield and its components. Moreover, salt stress induced a significant accumulation of some osmoprotectants (total soluble sugars (TSS) and amino acids, especially proline) and triggered the accumulation of hydrogen peroxide (H2O2) and lipid peroxidation in wheat leaves. In contrast, arginine and SNP treatments significantly mitigated the negative impacts of salinity on growth and productivity via enhancing photosynthetic pigments, nitrate reductase, phenolic compounds, IAA, TSS, free amino acids, and proline. In addition, SNP and arginine potentially reduced oxidative damage by decreasing H2O2 and lipid peroxidation through the induction of antioxidant enzymes. The individual amino acid composition of wheat grains under the interactive effect of salinity and NO sources has been scarcely documented until now. In this study, the NO sources restrained the reduction in essential amino acids (isoleucine and lysine) of wheat grains under salinity stress and further stimulated the contents of non-essential and total aromatic amino acids. Interestingly, the applied protectants recovered the decrease in arginine and serine induced by salinity stress. Thus, SNP or arginine at the levels of 5.0 and 20 mM, respectively, had a profound effect on modulating the salt stress of wheat throughout the life cycle.

Serum protein concentration and amino acid profile of HIV/HBV co-infected subjects on HAART in Plateau State, Nigeria.

Human immunodeficiency virus (HIV) and hepatitis B virus (HBV) are currently two important blood-borne human pathogens of major public health concern with high prevalence rates in Africa. The study assessed the impact of HIV and HBV mono- and co-infections on serum total protein, albumin, globulin fractions and plasma free amino acids concentrations. This was a cross-sectional study on adult (25 - 64 years old) patients on Highly Active Antiretroviral Therapy attending AIDS Preventive Initiative in Nigeria Centre, Jos University Teaching Hospital, Plateau State, Nigeria. It involved 80 subjects; 20 HIV/HBV co-infected, 20 each of HIV and HBV mono-infected controls, and 20 seronegative controls. Significant (p<0.05) increases in total protein and gamma globulin but a reduction in albumin concentrations were observed in the HIV/HBV co-infected group. Similarly, significant (p<0.05) increases in alpha-1 and alpha-2 globulin concentrations were observed in the mono- and co-infected groups compared to the seronegative control group. There were significant (p<0.05) increases in the glucogenic, aromatic and branched-chain amino acid concentrations of the HIV/HBV co-infected subjects. The study suggests prognostic importance of alpha and gamma globulin fractions of serum protein as well as amino acid profile in the management of HIV/HBV co-infection.

Influence of ultrasound treatment on the physicochemical and antioxidant properties of mung bean protein hydrolysate

This study aimed to investigate influence of ultrasonic treatment on physicochemical and antioxidant properties of mung bean protein hydrolysate (MPH). Physicochemical properties of MPH were evaluated by Tricine-SDS-PAGE, particle size distribution, fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy, among others. Radicals scavenging activities of ABTS, hydroxyl, superoxide anion, Fe2+ chelating ability and reducing power characterized antioxidant activities of MPH. MPH contained four bands of 25.6, 12.8, 10.6 and 4.9 kDa, in which 4.9 kDa was the most abundant. Ultrasonic treatment increased the contents of aromatic and hydrophobic amino acids in MPH. Ultrasonic treatment decreased the content of α-helix of MPH and increased β-sheet and β-turn compared to MPH. MPH-546 W (ultrasonic treatment 546 W, 20 min) had the lowest average particle size (290.13 nm), zeta potential (-36.37 mV) and surface hydrophobicity (367.95 A.U.). Antioxidant activities of ultrasonicated-MPH increased with the ultrasonic power, achieving the lowest IC50 (mg/mL) of 0.1087 (ABTS), 1.796 (hydroxyl), 1.003 (superoxide anion) and 0.185 (Fe2+ chelating ability) in 546 W power. These results indicated ultrasonic treatment would be a promising method to improve the antioxidant properties of MPH, which would broaden the application scope of MPH as bioactive components in the food industry.

Rapid Detection of Three Common Bacteria Based on Fluorescence Spectroscopy.

As an important part of environmental water quality monitoring, efficient bacterial detection has attracted widespread attention. Among them, LIF (laser-induced fluorescence) technology has the characteristics of high efficiency and sensitivity for bacterial detection. To simplify the experimental process of bacterial detection, fluorescence emission spectra of E. coli (Escherichia coli) and its deactivated controls, K. pneumoniae (Klebsiella pneumoniae) and S. aureus (Staphylococcus aureus), were analyzed with fluorescence excitation by a 266 nm laser. By analyzing the results, it was found that the dominant fluorescence peaks of bacterial solutions at 335~350 nm were contributed by tryptophan, and the subfluorescence peaks at 515.9 nm were contributed by flavin; besides, K. pneumoniae and S. aureus had their own fluoresces characteristics, such as tyrosine contributing to sub-fluorescence peaks at 300 nm. The three species of bacteria can be differentiated with whole fluorescence spectrum by statistically analysis (p < 0.05), for various concentrations of aromatic amino acids and flavin in different bacteria. The experimental results also proved that the inactivation operation did not alter the spectral properties of E. coli. The indexes of fluorescence intensity and FIR (fluorescence intensity ratio, I335~350/I515.9) can be used to retrieve the bacteria concentration as well as for bacteria differentiation using the index of slopes. The detection limit of bacteria is less than ~105 cell/mL using laser induced fluorescence methods in the paper. The study demonstrated the rapid detection capability of the LIF bacterial detection system and its great potential for rapid quantitative analysis of bacteria. This may bring new insight into the detection of common bacteria in water in situ.

Metabolic Effects of Violet Light on Spoilage Bacteria from Fresh-Cut Pakchoi during Postharvest Stage.

Pakchoi (Brassica rapa L. Chinensis) is an important vegetable in Asia. Pseudomonas palleroniana is one of the specific spoilage organisms (SSOs) of fresh-cut pakchoi. The purpose of this study was to investigate changes to the endogenous metabolic spectrum of violet light (405 nm) with regard to food spoilage bacteria from fresh-cut pakchoi using ultrahigh-performance liquid chromatography-tandem mass spectrometry. In this study, P. palleroniana samples were treated with violet light at 4 °C, and the maximum dose was 133.63 J/cm2. The results revealed that 153 metabolites and 83 pathways significantly changed compared to the control group, which indicated that light treatment may lead to ROS accumulation in cells, inducing oxidative stress and the excessive consumption of ATP. However, the increased content of aromatic amino acids and the decreased anabolism of some amino acids and nucleotides might be a form of self-protection by reducing energy consumption, thus contributing to the improvement of the tolerance of cells to illumination. These results provide new insights into the antibacterial mechanism of P. palleroniana with regard to metabolism.

Peptides derived from the gastrointestinal digestion of amaranth 11S globulin: Structure and antioxidant functionality

The relationship between structural and physicochemical properties and antioxidant activity of peptides from amaranth 11S-globulin was studied. Peptides AWEEREQGSR, TEVWDSNEQ, IYIEQGNGITGM and YLAGKPQQEH had the greatest in vitro activity (ORAC, HORAC). GDRFQDQHQ, HVIKPPSRA and KFNRPETT were the most active ones against Cu+2/H2O2-induced-LDL oxidation. In a cellular system (H2O2-induced-Caco2-TC7), TEVWDSNEQ, IYIEQGNGITGM, GDRFQDQHQ, LAGKPQQEHSGEHQ and KFNRPETT were the most effective in decreasing ROS, while the effects on SOD, GPx, and GSH were variable. To understand the structure–antioxidant activity relationships, the content of aromatic and acidic amino acids, the degree of hydrophobicity and the charge distribution on the accessible surface of peptides structures obtained by molecular dynamics were analysed. The low correlation between in vitro, ex vivo and cellular activities could be explained by the influence of physicochemical and structural properties on the interaction with complex systems (LDL/cells), peptide modifications and/or mechanisms other than direct ROS inhibition in the cells.

Systematic investigation of the amino acid profiles that are correlated with xanthine oxidase inhibitory activity: Effects, mechanism and applications in protein source screening

This study aimed to investigate the dipeptide amino acid profiles correlated with xanthine oxidase (XOD) inhibitory activity and guide screening to determine suitable sources for XOD inhibitor protein hydrolysate preparation. The XOD inhibitory activities of 400 dipeptides were predicted via molecular docking and measured in vitro, and amino acids containing aromatic structures and charged residues were correlated with high XOD inhibitory properties. Subsequently, the effects of Cys-Glu and Lys-Glu, which showed the highest in vitro activities, were examined in hyperuricaemic mice, and were found to alleviate hyperuricaemia and modulate the gut microbiota. Furthermore, a suitable protein from Oreochromis mossambicus with high contents of charged (8.6%) and aromatic (1.67%) amino acids was screened, and the in vitro inhibitory rates of protein hydrolysate prepared from O. mossambicus against XOD were found to be 21.90% and 44.51% at 40 and 100 mg/ml, respectively. This study provides a strategy for screening protein hydrolysate sources with certain activities based on amino acid profiles.

Effect of a very low negative dietary cation-anion difference (DCAD) diet on plasma and urine metabolomics of prepartum Holstein cows

The objectives of this cross-sectional, nonintervention, observational study were to compare urine and blood parameters between cows consuming a positive dietary cation-anion difference (DCAD) diet [early dry cows, DCAD + 250 mEq/kg of dry matter (DM), n = 15] with the same cows consuming a negative DCAD diet (−220 mEq/kg of DM) 10 d after moving them from the early dry to the prepartum group. The most remarkable finding was that cows consuming the anionic diet had very low urine pH and very low base excess in blood, suggestive of uncompensated metabolic acidosis. Importantly, the metabolomics data revealed that only urine concentrations of essential and aromatic amino acids were decreased, and that concentrations of total nonessential amino acids and glucogenic amino acids were increased in plasma and reciprocally decreased in urine, suggesting that the cows fed anionic salts were attempting to meet a high glucose demand by mobilizing gluconeogenic amino acid reserves. Notably, the dietary anionic salts exerted marked effects on glycerophospholipids, with a reduction in most phosphatidylcholine containing diacyl (PC aa) and acyl-alkyl (PC ae) moieties in plasma and urine. Further characterization of these metabolomic profiles may lead to the development of novel biomarkers to identify cows susceptible to metabolic acidosis and other metabolic diseases.