Pyroglutamic Acid Research Articles

Synergistic anti-fungal action of azole compounds with mixed ligand complexes and their applications

Selenium (Se (II)) and Zinc (Zn (II)) mixed ligand complexes containing glycine (gly) and pyroglutamic acid (l-PCA) as primary ligands, and salicylic acid (HL1) and glycolic acid (HL2) as secondary ligands have been prepared. These novel complexes were characterized using elemental analysis, 1H NMR, 13CNMR, UV–Vis., FTIR, X-ray diffraction, mass spectra and thermal analysis. The elemental analysis revealed the formation of [1:1:1] zinc or selenium amino acid-hydroxy acid complexes.The bonds interactions between Se (II), Zn (II), and ligands had been investigated using IR spectrophotometry revealing that the ligands exhibited neutral bidentate behavior; the amino acid (primary ligand) coordinates through the nitrogen atom and the carbonyl group's oxygen atom, whereas the hydroxy acids HL1 and HL2 (secondary ligands) coordinate through the OH group and the carbonyl group's oxygen atom.Electronic absorption spectra of the mixed-ligand complexes indicate a square planar shape. The prepared mixed ligand complexes were encapsulated with another powerful antifungal agent, climbazole, in nanostructured lipid carriers (NLCs) for topical application to improve the therapeutic activity. The NLCs were prepared by a hot homogenization method and characterized by particle size, drug entrapment, in vitro drug release, and zeta potential to guarantee the stability of the desired nanostructured lipid carriers (NLCs). The microbiological activity of climbazole-mixed ligand complexes and their encapsulated forms were assessed against Malassezia furfur, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Escherichia coli. In comparison to Se (II) and Zn (II) mixed ligand complexes alone, the study revealed that the combination of Se (II) and Zn (II) mixed ligand complexes with climbazole in NLCs considerably increased antibacterial activity against the tested microbial strains. P ≤ 0.05 indicates statistical significance for the difference.

Metabolites from a Pleurotus tuber-regium collected in Madagascar

Pleurotus tuber-regium was isolated from a dead trunk of Raphia farinifera (Arecaceae) in a lowland moist forest in Antsohihy, Madagascar, and the species was confirmed by molecular analysis and morphological observations. The main bioactive metabolites of the mycelium extracts were identified by mass spectrometry techniques. Five structural diverse metabolites, tryptophol, pyroglutamic acid, prolyldiketopiperazine B, sporol and RKS-1778, were characterised by LC-MS qTOF analysis of the hydro-alcoholic extract. GC-MS analysis of both chloroform and ethyl acetate extracts revealed the presence of several saturated and ­unsaturated fatty acids and their esters derivatives.

Nutritionally enriched tomatoes (Solanum lycopersicum L.) grown with wood distillate: chemical and biological characterization for quality assessment.

Bio-based products are nowadays useful tools able to affect the productivity and quality of conventionally cultivated crops. Several bio-based products are currently on the market; one of the newest and most promising is the wood distillate (WD) derived from the pyrolysis process of waste biomass after timber. Its foliar application has been widely investigated and shown to promote the antioxidant profile of cultivated crops. WD was used here as additive for the cultivation of tomato (Solanum lycopersicum L.) plants. The application improved quality (chemical) parameters, minerals, polyphenols, and lycopene contents of tomato fruits. The extracts of WD-treated and untreated tomatoes have been chemically and biologically characterized. The 1 H-NMR and ESI-mass spectrometry analyses of the extracts revealed the presence of different fatty acids, amino acids and sugars. In particular, the WD-treated tomatoes showed the presence of pyroglutamic acid and phloridzin derivatives, but also dihydrokaempferol, naringenin glucoside, cinnamic acid, and kaempferol-3-O-glucoside. When tested in cells, the extracts showed a promising anti-inflammatory profile in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Furthermore, the extracts displayed a slight vasorelaxant activity on rat aorta rings (either endothelium-denuded or endothelium-intact) pre-contracted with phenylephrine or potassium chloride. PRACTICAL APPLICATION: Wood distillate has been used for tomato plant growth. Tomatoes showed improved nutritional parameters, and their extracts displayed antioxidant and anti-inflammatory activities.

Evidence of abnormality in glutathione metabolism in the airways of preterm born children with a history of bronchopulmonary dysplasia

Preterm-born children are at risk of long-term pulmonary deficits, including those who developed bronchopulmonary dysplasia (BPD) in infancy, however the underlying mechanisms remain poorly understood. We characterised the exhaled breath condensate (EBC) metabolome from preterm-born children, both with and without BPD. Following spirometry, EBC from children aged 7–12 years, from the Respiratory Health Outcomes in Neonates study, were analysed using Time-of-Flight Mass Spectrometry. Metabolite Set Enrichment Analysis (MSEA) linked significantly altered metabolites to biological processes. Linear regression models examined relationships between metabolites of interest and participant demographics. EBC was analysed from 214 children, 144 were born preterm, including 34 with BPD. 235 metabolites were detected, with 38 above the detection limit in every sample. Alanine and pyroglutamic acid were significantly reduced in the BPD group when compared to preterm controls. MSEA demonstrated a reduction in glutathione metabolism. Reduced quantities of alanine, ornithine and urea in the BPD group were linked with alteration of the urea cycle. Linear regression revealed significant associations with BPD when other characteristics were considered, but not with current lung function parameters. In this exploratory study of the airway metabolome, preterm-born children with a history of BPD had changes consistent with reduced antioxidant mechanisms suggesting oxidative stress.

Untargeted plasma metabolomics and risk of colorectal cancer—an analysis nested within a large-scale prospective cohort

BackgroundColorectal cancer (CRC) is a leading cause of cancer-related death worldwide, but if discovered at an early stage, the survival rate is high. The aim of this study was to identify novel markers predictive of future CRC risk using untargeted metabolomics.MethodsThis study included prospectively collected plasma samples from 902 CRC cases and 902 matched cancer-free control participants from the population-based Northern Sweden Health and Disease Study (NSHDS), which were obtained up to 26 years prior to CRC diagnosis. Using reverse-phase liquid chromatography–mass spectrometry (LC–MS), data comprising 5015 metabolic features were obtained. Conditional logistic regression was applied to identify potentially important metabolic features associated with CRC risk. In addition, we investigated if previously reported metabolite biomarkers of CRC risk could be validated in this study population.ResultsIn the univariable analysis, seven metabolic features were associated with CRC risk (using a false discovery rate cutoff of 0.25). Two of these could be annotated, one as pyroglutamic acid (odds ratio per one standard deviation increase = 0.79, 95% confidence interval, 0.70–0.89) and another as hydroxytigecycline (odds ratio per one standard deviation increase = 0.77, 95% confidence interval, 0.67–0.89). Associations with CRC risk were also found for six previously reported metabolic biomarkers of prevalent and/or incident CRC: sebacic acid (inverse association) and L-tryptophan, 3-hydroxybutyric acid, 9,12,13-TriHOME, valine, and 13-OxoODE (positive associations).ConclusionsThese findings suggest that although the circulating metabolome may provide new etiological insights into the underlying causes of CRC development, its potential application for the identification of individuals at higher risk of developing CRC is limited.

A novel metalloproteinase-derived cryptide from Bothrops cotiara venom inhibits angiotensin-converting enzyme activity

Snake venoms are primarily composed of proteins and peptides, which selectively interact with specific molecular targets, disrupting prey homeostasis. Identifying toxins and the mechanisms involved in envenoming can lead to the discovery of new drugs based on natural peptide scaffolds. In this study, we used mass spectrometry-based peptidomics to sequence 197 peptides in the venom of Bothrops cotiara, including a novel 7-residue peptide derived from a snake venom metalloproteinase. This peptide, named Bc-7a, features a pyroglutamic acid at the N-terminal and a PFR motif at the C-terminal, homologous to bradykinin. Using FRET (fluorescence resonance energy transfer) substrate assays, we demonstrated that Bc-7a strongly inhibits the two domains of angiotensin converting enzyme (Ki < 1 μM). Our findings contribute to the repertoire of biologically active peptides from snake venoms capable of inhibiting angiotensin-converting enzyme (ACE), beyond current known structural motifs and precursors. In summary, we report a novel snake venom peptide with ACE inhibitory activity, suggesting its potential contribution to the hypotensive effect observed in envenomation.

THU307 Landscapes Of MaternalAnd Neonatal Bacterial And Metabolic SignaturesAnd Their Interaction In Gestational Diabetes Mellitus

Abstract Disclosure: L. Ding: None. J. Liu: None. X. Zhai: None. X. Xiao: None. Background: Gestational diabetes mellitus (GDM) is strongly correlated with considerable risks to both the mother and the developing fetus. Although evidence indicates an association between the altered gut microbiota and GDM, the microbial and metabolic mechanisms that link the metabolic state between mothers and offspring are unknown. This study aims to characterize the maternal and neonatal bacterial and metabolic signatures and their interaction in gestational diabetes mellitus. Methods: Sixty-six mothers (39 women with GDM and 27 normal pregnant women) and eighty-nine newborns (44 from GDM mothers and 45 from normal mothers) were included in this study. Using 16S rRNA gene sequencing and untargeted metabolomic methods, we determined the gut microbiota and serum metabolomics both for mothers and newborns. Results: We found that the microbial and metabolic signatures of GDM mothers and newborns were significantly different from those of the Control group (Ctr), respectively. Intriguingly, we identified 14 genera (Phyllobacterium, etc.) that exhibited identical alterations in mothers and newborns between groups. Among the overlapped differential metabolites in mothers and newborns, 23 (Glutamyl-methionine, etc.) showed consistent alterations between groups, while 19 (Cyclotetradecane, etc.) metabolites exhibited opposite alterations. Metabolic KEGG pathway analysis revealed that 6 pathways, including fatty acid metabolism, sphingolipid metabolism, TCA cycle, transsulfuration pathway, bile acid metabolism, and carnitine metabolism were both enriched in mothers and newborns. Significantly, correlation analysis revealed the notable association between pyroglutamic acid and maternal glucose level in Ctr group was disrupted in GDM group (Ctr: r = -0.46, p = 0.02; GDM: r = 0.04, p = 0.82). Simultaneously, pyroglutamic acid was significantly correlated with neonate serum high-density lipoprotein cholesterol level, which was disrupted in newborns of GDM mothers (Ctr: r = 0.33, p = 0.03; GDM: r = -0.05, p = 0.80). Conclusion: Altogether, we demonstrated that GDM could consistently alter the microbiota and serum metabolome in mothers and newborns, which is significantly associated with their metabolic state respectively. These findings indicate that serum metabolites serve as promising targets to intervene in metabolic transmission in GDM, which needs further validation. Presentation: Thursday, June 15, 2023

N-(2-Aminophenyl)-benzamide Inhibitors of Class I HDAC Enzymes with Antiproliferative and Antifibrotic Activity.

Inhibitors of histone deacetylases (HDACs) have received special attention as novel anticancer agents. Among various types of synthetic inhibitors, benzamides constitute an important class, and one is an approved drug (chidamide). Here, we present a novel class of HDAC inhibitors containing the N-(2-aminophenyl)-benzamide functionality as the zinc-binding group linked to various cap groups, including the amino acids pyroglutamic acid and proline. We have identified benzamides that inhibit HADC1 and HDAC2 at nanomolar concentrations, with antiproliferative activity at micromolar concentrations against A549 and SF268 cancer cell lines. Docking studies shed light on the mode of binding of benzamide inhibitors to HDAC1, whereas cellular analysis revealed downregulated expression of EGFR mRNA and protein. Two benzamides were investigated in a mouse model of bleomycin-induced pulmonary fibrosis, and both showed efficacy on a preventative dosing schedule. N-(2-Aminophenyl)-benzamide inhibitors of class I HDACs might lead to new approaches for treating fibrotic disorders.

DETERMINATION OF FREE AMINO ACIDS IN UNDERGROUND ORGANS OF ELEUTHEROCOCCUS SENTICOSUS RUPR. ET MAXIM

A study of free amino acids in the underground organs of Eleutherococcus senticosus (Eleutherococcus senticosus Rupr. et Maxim, family Araliaceae) was carried out. The material for the study was samples of rhizomes and roots of Eleutherococcus collected in the Amur Region, Jewish Autonomous Region, Primorsky and Khabarovsk Territories.&#x0D; Amino acids were determined by GC-MS. According to the results of studies, from two to nine amino acids were found in the rhizomes and roots of Eleutherococcus senticosus, of which 6 are nonessential (alanine, proline, serine, glutamine, pyroglutamic acid, aspartic acid) and 3 are essential (valine, leucine, threonine). The total content of amino acids in the studied samples averaged 20.1 mg/100 g. It was revealed that the dominant group is heterocyclic amino acids, the representatives of which include proline and pyroglutamic acid. The average content of proline and pyroglutamic acid was 4.9 and 7.1 mg/100 g, respectively. Based on a comparative analysis of the amino acid composition of ten samples, it was shown that the amino acid composition of the rhizomes and roots of Eleutherococcus from different populations varies. As a result of a cluster analysis based on the content of amino acids in the studied samples, two groups are distinguished: samples from the Khabarovsk Territory - Amur Region, samples from the Primorsky Territory - Jewish Autonomous Region (Leninsky District).

Promotion or Inhibition Effects of Exogenous Glutathione-Degraded Amino Acids on the Formation of 2,3-Butanedione and Pyrazines via Varied Pathways of Interaction with α-Dicarbonyl Compounds Derived from N-(1-Deoxy-d-xylulos-1-yl)-alanine.

The contribution of glutathione (GSH) and free amino acids degraded from GSH to the generation of pyrazines and 2,3-butanedione was illustrated during their interaction in the thermal treatment of the Amadori compound of alanine and xylose (ARP). GSH-degraded amino acids, glutamic acid (Glu), cysteine (Cys), and glycine (Gly), but not pyroglutamic acid (pGlu), could effectively capture α-dicarbonyls to facilitate the formation of pyrazines when ARP was heated with GSH. Deoxypentosones, the precursors of 2,3-butanedione, were largely consumed in the ARP-GSH model by the interaction with GSH and its degradative Cys compared with the ARP model. The addition of GSH and deoxypentosones inhibited the further degradation of deoxypentosones, resulting in less formation of 2,3-butanedione and other α-dicarbonyl compounds. Meanwhile, the reaction between GSH-degraded Cys and deoxypentosones to form sulfur-containing compounds such as thiols accelerated the consumption of deoxypentosones; thereby, the formation of 2,3-butanedione was severely interfered. However, this inhibition was compensated for by the GSH-degraded Gly through the addition between Gly and MGO and the subsequent deamination. The involvement of exogenous GSH could simultaneously boost the yields of 2,3-butanedione and pyrazines compared with those of ARP heated alone. As the degree of GSH degradation strengthened in the ARP-thermal-degraded GSH models, the yields of both pyrazines and 2,3-butanedione steadily increased.

Serum metabolomics profiling by proton nuclear magnetic resonance spectrometry of the response to single oral macronutrient challenges in women with polycystic ovary syndrome (PCOS) compared with male and female controls

BackgroundThe polycystic ovary syndrome (PCOS) is associated with insulin resistance, obesity and cardiometabolic comorbidities. We here challenged the hypothesis, using state-of-the-art proton nuclear magnetic resonance spectrometry (1H-NMRS) metabolomics profiling, that androgen excess in women induces a certain masculinization of postprandial metabolism that is modulated by obesity.Materials and methodsParticipants were 53 Caucasian young adults, including 17 women with classic PCOS consisting of hyperandrogenism and ovulatory dysfunction, 17 non-hyperandrogenic women presenting with regular menses, and 19 healthy men, selected to be similar in terms of age and body mass index (BMI). Half of the subjects had obesity. Patients were submitted to isocaloric separate glucose, lipid and protein oral challenges in alternate days and fasting and postprandial serum samples were submitted to 1H-NMRS metabolomics profiling for quantification of 36 low-molecular-weight polar metabolites.ResultsThe largest postprandial changes were observed after glucose and protein intake, with lipid ingestion inducing smaller differences. Changes after glucose intake consisted of a marked increase in carbohydrates and byproducts of glycolysis, and an overall decrease in byproducts of proteolysis, lipolysis and ketogenesis. After the protein load, most amino acids and derivatives increased markedly, in parallel to an increase in pyruvate and a decrease in 3-hydroxybutyric acid and glycerol. Obesity increased β- and d-glucose and pyruvate levels, with this effect being observed mostly after glucose ingestion in women with PCOS. Regardless of the type of macronutrient, men presented increased lysine and decreased 3-hydroxybutyric acid. In addition, non-obese men showed increased postprandial β-glucose and decreased pyroglutamic acid, compared with non-obese control women. We observed a common pattern of postprandial changes in branched-chain and aromatic amino acids, where men showed greater amino acids increases after protein intake than control women and patients with PCOS but only within the non-obese participants. Conversely, this increase was blunted in obese men but not in obese women, who even presented a larger increase in some amino acids compared with their non-obese counterparts. Interestingly, regardless of the type of macronutrient, only obese women with PCOS showed increased leucine, lysine, phenylalanine and tryptophan levels compared with non-obese patients.ConclusionsSerum 1H-NMRS metabolomics profiling indicated sexual dimorphism in the responses to oral macronutrient challenges, which were apparently driven by the central role of postprandial insulin effects with obesity, and to a lesser extent PCOS, exerting modifying roles derived from insulin resistance. Hence, obesity impaired metabolic flexibility in young adults, yet sex and sex hormones also influenced the regulation of postprandial metabolism.Graphical abstract

An in-depth and in vitro evaluation of the antioxidant and neuroprotective activity of aqueous and ethanolic extract of Asparagus racemosus Linn seed

The study aimed to explore the phytochemicals present in the aqueous and ethanolextracts of Asparagus racemosus Linn seeds by GC-MS and LC-MS analysis and to determine the neuro protective and antioxidant potential of both the extracts. The GC-MS and LC-MS analysis of the aqueous and ethanol seed extract indicated the presence of various chemical constituents such as ascorbic acid, hydroxycinnamic acid, fatty acids, pyroglutamic acid, pentanoic acid, decanoic acid, hexadecanoic acid, naphthalene, hydroxycinnamic acid, thiamine hydrochloride, coumaroyl putrescin, agrimol, epanorin, brevicarine, rubiadin, pyroglutamic acid, tyrosine derivative, linoleyl acetate etc. Neuroprotective effect of aqueous and ethanol extracts of Asparagus racemosus Linn seeds on SHSY5Y cell line was evaluated by MTT assay and the results showedthat ethanol extract of the plant got more neuroprotective activity on cell lines. The antioxidant results showed that both of the extracts had almost similar DPPH and ABTS radical scavenging. However, the ethanol extract had more potent antioxidant power than the aqueous extract. Study data suggest that whole plant of Asparagus racemosus Linn seeds possessed neuroprotective and anti-oxidative activities and the best neuroprotective and anti-oxidant activity being exhibited by the ethanolic extract of the plant.

Profiling of primary and phytonutrients in edible mahlab cherry (Prunus mahaleb L.) seeds in the context of its different cultivars and roasting as analyzed using molecular networking and chemometric tools.

Prunus mahaleb L. (mahlab cherry) is a deciduous plant that is native to the Mediterranean region and central Europe with a myriad of medicinal, culinary and cosmetic uses. The present study explored different cultivars of mahlab (white from Egypt and Greece, red from Egypt and post roasting). UPLC-MS led to the detection of 110 primary and secondary metabolites belonging to different classes including phenylpropanoids (hydroxy cinnamates, coumaroyl derivatives), organic acids, coumarins, cyanogenic glycosides, flavonoids, nitrogenous compounds, amino acids and fatty acids, of which 39 are first time to be detected in Prunus mahaleb L. A holistic assessment of metabolites was performed for further analysis of dataset using principal component analysis (PCA) among mahlab cultivars to assess variance within seeds. The results revealed that phenolic acids (coumaric acid-O-hexoside, ferulic acid-O-hexoside, ferulic acid-O-hexoside dimer, dihydrocoumaroyl-O-hexoside dimer and ferulic acid), coumarins (coumarin and herniarin) and amino acids (pyroglutamic acid) were abundant in white mahlab cultivars (cvs.) from different locations. In contrast, red mahlab and its roasted seeds were more rich in organic acids (citric and malic acids), amygdalin derivative and sphingolipids. Orthogonal projections to latent structures discriminant analysis (OPLS-DA) revealed for markers in red mahlab and in response to roasting, where red mahlab was rich in nitrogenous compounds viz. nonamide, deoxy fructosyl leucine, glutaryl carnitine and isoleucine, while roasted product (REM) was found to be enriched in choline.

Discovery of color compounds: Integrated multispectral omics on exploring critical colorant compounds of black tea infusion

The present study provided a highly efficient and systematic workflow for identifying colorants of food and beverage. Generally, the objective colorimeter and subjective human eye had different systems to identify colors, which makes the color description very challenging. Here, the Lab/LCH color system was applied to clearly illustrate color changes. Our workflow was applied to determine and verify the differential colorant substances between two groups of black tea infusions. Regarding color parameters, the infusions of black tea from Camellia sinensis and Camellia assamica differed significantly. The differential substances between black tea infusions were correlated to color parameters by mass spectrometry and nuclear magnetic resonance based multivariate statistical analysis and verified by machine learning tool. Pyroglutamic acid–glucose Amadori product, quercetin-3-O-glucoside, quinic acid and theabrownins were identified as main color contributors to black teas’ color difference, which were also verified by addition test with standard black tea infusion.

Kinetics of Formation of Butyric and Pyroglutamic Acid during the Shelf Life of Probiotic, Prebiotic and Synbiotic Yoghurt

Butyric acid (C4) and pyroglutamic acid (pGlu) exert significant beneficial effects on human health. In this study, the influence of probiotics (Lactobacillus acidophilus and Bifidobacteria) and/or prebiotics (1 and 3% inulin and fructo-oligosaccharides) on the content of C4 and pGlu in yoghurt during the shelf-life period was evaluated. The contents of C4 and pGlu were determined in probiotic, prebiotic and synbiotic yoghurts during 30 days of storage at 4 °C by solid-phase microextraction coupled with gas chromatography/mass spectrometry and HPLC analysis. Traditional yoghurt and uninoculated milk were used as control. Prebiotic yoghurt contained more C4 (2.2–2.4 mg/kg) than the uninoculated milk, and no increase was detected with respect to traditional yoghurt. However, probiotic yoghurt showed 10% more C4 than traditional yoghurt. Adding fibre to probiotics (synbiotic yoghurt) the C4 content increased by 30%. Regarding pGlu, probiotic yoghurt presented the highest content of approximately 130 mg/100 g. Fibre did not affect pGlu content. Finally, C4 and pGlu contents generally increased up to 20 days of storage and then decreased up to 30 days of storage. The results might be useful for the preparation of other functional foods rich in C4 and pGlu using lactic acid bacteria.

Improved syntheses of P2X7 ligands based on substituted benzyl amide of pyroglutamic acid motif labelled with iodine-123 or iodine-125

P2X7 sites are emerging targets for molecular imaging research, notably in the context of neurodegeneration and inflammatory conditions. Therefore, we prepared a precursor for (radio)iodination of the P2X7 ligand VPGIS191. We then developed a radioiodination method with 123I for SPECT with a radiochemical yield of 71 ± 13% and 125I for autoradiography with a radiochemical yield of 85 ± 6% Autoradiography of [125I]VPGIS191 in mouse brain cryostat sections demonstrated approximately 36 nM binding affinity and Bmax of approximately 400 pmol/gram tissue for P2X7 binding sites. VPGIS191 (cis) had a two-fold lower affinity compared to its geometric trans-isomer TZ6019.Graphical abstract

Pyroglutamination-Induced Changes in the Physicochemical Features of a CXCR4 Chemokine Peptide: Kinetic and Structural Analysis.

We investigate the physicochemical effects of pyroglutamination on the QHALTSV-NH2 peptide, a segment of cytosolic helix 8 of the human C-X-C chemokine G-protein-coupled receptor type 4 (CXCR4). This modification, resulting from the spontaneous conversion of glutamine to pyroglutamic acid, has significant impacts on the physicochemical features of peptides. Using a static approach, we compared the transformation in different conditions and experimentally found that the rate of product formation increases with temperature, underscoring the need for caution during laboratory experiments to prevent glutamine cyclization. Circular dichroism experiments revealed that the QHALTSV-NH2 segment plays a minor role in the structuration of H8 CXCR4; however, its pyroglutaminated analogue interacts differently with its chemical environment, showing increased susceptibility to solvent variations compared to the native form. The pyroglutaminated analogue exhibits altered behavior when interacting with lipid models, suggesting a significant impact on its interaction with cell membranes. A unique combination of atomic force microscopy and infrared nanospectroscopy revealed that pyroglutamination affects supramolecular self-assembly, leading to highly packed molecular arrangements and a crystalline structure. Moreover, the presence of pyroglumatic acid has been found to favor the formation of amyloidogenic aggregates. Our findings emphasize the importance of considering pyroglutamination in peptide synthesis and proteomics and its potential significance in amyloidosis.

DBU-catalyzed Michael additions of bulky glycine imine to β-arylfuryl substituted α,β-unsaturated esters

DBU-catalyzed Michael reactions between tert-butyl 2-((diphenylmethylene) amino)acetate and simple β-substituted α,β-unsaturated esters have been achieved in high yields (up to 95% yield) and diastereoselectivties (up to 99:1 dr) in the presence of 1.0 eq. of LiBr in acetonitrile under room temperature. The Michael adduct can be easily converted into trans-3-substituted pyroglutamic acid ester through in-situ acidic hydrolysis following lactamation.

In Vitro Bioactivities of Commonly Consumed Cereal, Vegetable, and Legume Seeds as Related to Their Bioactive Components: An Untargeted Metabolomics Approach Using UHPLC-QTOF-MS2.

We conducted a comprehensive evaluation of the antioxidant, anti-obesity, anti-diabetic, and anti-glycation activities associated with the consumption of broccoli, red cabbage, alfalfa, and buckwheat seeds. Additionally, we explored the relationship between these biological activities and the profiles of amino acids, polyphenols, and organic acids identified in the seeds. Our findings demonstrated that red cabbage, broccoli, and buckwheat extracts exhibited significantly higher antioxidant potential compared to the alfalfa extract. Moreover, buckwheat displayed the most significant capacity for inhibiting alpha-glucosidase. Remarkably, broccoli and red cabbage demonstrated substantial anti-glycation and lipase inhibitory potentials. We identified the presence of amino acids, polyphenols, and organic acids in the extracts through untargeted metabolomics analysis. Correlation analysis revealed that pyroglutamic acid positively correlated with all the investigated functional properties. Most polyphenols made positive contributions to the functional properties, with the exception of ferulic acid, which displayed a negative correlation with all tested biological activities. Furthermore, gluconic acid and arabinonic acid among the organic acids identified displayed a positive correlation with all the functional properties. These results strongly support the anti-diabetic, anti-obesity, and anti-glycation potential of red cabbage, broccoli, and buckwheat seeds.

In Silico Analysis of Individual Fractions of Bovine Casein as Precursors of Bioactive Peptides—Influence of Post-Translational Modifications

Bovine casein is one of the most known precursors of bioactive peptides among food proteins. Thus far, in silico investigations addressing casein have taken no account of the impact of modifications of amino acid residues on the feasibility of bioactive peptide release. The present study aimed to determine the effect of such modification on the possibility of release of bioactive peptides from casein during simulated digestion. The αs1-, αs2-, β-, and κ-casein sequences were deposited in the BIOPEP-UWM protein database considering phosphorylated amino acids, cysteine residues forming disulfide bridges, and pyroglutamic acid residues. The frequency of occurrence of bioactive fragments and the frequency of their release by digestive enzymes were determined for the analyzed modified and unmodified proteins. Peptides found exclusively in the sequences of unmodified proteins were deemed as false-positive results. From 1.74% (β-casein A2) to 4.41% (αs2-casein B and D) of the false-positive results were obtained for the total frequency of occurrence of bioactive fragments (sums of frequencies computed for all activities). In turn, from 1.78% (κ-casein B) to 9.18% (β-casein A2 and A3) of false-positive results were obtained for the predicted total frequency of release of bioactive peptides by the system of digestive enzymes (pepsin, trypsin, and chymotrypsin).