Search Results (3,047)

Since its discovery in higher plants, melatonin has attracted considerable attention for its antioxidant properties and its diverse roles in plant physiology and stress responses. However, its biosynthetic pathway remains only partially elucidated, particularly in horticultural crops of economic and nutritional importance, such as pepper (Capsicum annuum L.) fruits. In our previous work, we identified five genes encoding tryptophan decarboxylase (TDC), the first enzyme in the melatonin biosynthetic pathway in pepper. The present study expands on this by identifying and characterizing additional genes encoding enzymes involved in subsequent steps of the pathway, including four tryptamine 5-hydroxylase (T5H) genes, two serotonin N-acetyltransferase (SNAT) genes, three N-acetylserotonin O-methyltransferase (ASMT) genes, two caffeic acid O-methyltransferase (COMT) genes, and one N-acetylserotonin deacetylase (ASDAC) gene, representing a total of twelve newly identified genes. We further examined their expression in sweet pepper fruits and found that only nine of the identified genes are expressed in the fruit, with generally higher transcript levels during the unripe stages. Melatonin quantification in the California-type ‘Masami’ cultivar using UPLC with fluorescence detection (FD) revealed concentrations of 623 ng melatonin·g⁻¹ dry weight (DW) in green fruits and 431 ng melatonin·g⁻¹ DW in red fruits, consistent with the higher expression of melatonin biosynthetic genes in unripe fruit. Expression analysis of these genes by means of RNA-seq revealed differential modulation in response to exogenous melatonin treatments (20, 50, and 100 µM). To our knowledge, this is the first report demonstrating that exogenous melatonin regulates the expression of genes involved in its own biosynthetic pathway in sweet pepper fruits. Notably, treatment with 100 µM melatonin delayed ripening in these non-climacteric fruits, highlighting its potential biotechnological application for controlling fruit ripening and improving postharvest management. Full article

The microbiota–gut–brain axis (MGBA) is a complex bidirectional communication network integrating neural, endocrine, immune, and metabolic pathways linking intestinal microbiota to central nervous system function. Increasing evidence indicates that microbiota-derived signals are critical regulators of neurodevelopment and may contribute to vulnerability to neurodegenerative disorders across the lifespan. In this narrative review, we synthesize experimental and clinical evidence to define the key biological mechanisms underlying microbiota–brain interactions. Converging data indicate that immune activation, barrier dysfunction, and microbial metabolites, particularly short-chain fatty acids and tryptophan-derived compounds, represent central mediators linking gut dysbiosis to neuroinflammatory and neurodegenerative processes. Early-life microbial perturbations, driven by factors such as antibiotic exposure, diet, and psychosocial stress, appear to induce long-term immunometabolic programming that may increase susceptibility to neurological disorders later in life. Clinical studies consistently associate dysbiosis with neurodevelopmental conditions and major neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease; however, causal relationships remain incompletely defined due to heterogeneity and the predominance of observational data. Overall, the available evidence supports a lifespan model in which microbiota-driven immune and metabolic dysregulation contributes to both early neurodevelopmental trajectories and late-life neurodegeneration. While microbiome-based biomarkers and therapeutic strategies show promise, their clinical translation requires validation in longitudinal and interventional studies. Full article

Conventional extraction of indigo, a vital natural dye, provides low yields and has a negative environmental impact. However, microbial synthesis has emerged as a sustainable alternative. In this study, we describe the optimization of indigo biosynthesis in an engineered Escherichia coli strain called E216. This strain carries, on a replicative plasmid, the styAB genes originating from Pseudomonas putida that constitute the monooxygenase biosynthetic pathway of indigo, as well as mdh, encoding malate dehydrogenase, which plays a role in reducing power generation. In this strain, the overexpression of mtr (a gene encoding a transporter of tryptophan (Trp), the precursor of indigo biosynthesis) and acrA (a gene encoding a protein involved in indigo efflux) was found to substantially enhance indigo yields. Consistently, knocking out these two genes using CRISPR-Cas9 significantly reduced indigo production, whereas it was restored through the complementation of these mutants. This study thus revealed that stimulating tryptophan uptake and indigo efflux, the latter of which limits indigo’s toxic intracellular accumulation, has a positive impact on indigo yields. Furthermore, a comparative mass spectrometry-based proteomic analysis of E216 grown in fermentation medium with or without tryptophan supplementation, integrated with data-independent acquisition (DIA), revealed the global impact of tryptophan supplementation on cellular metabolism. This analysis identified upregulation of key proteins and enriched metabolic pathways under conditions of tryptophan supplementation. Integrating the results of the genetic engineering and proteomic analysis establishes a strong scientific and practical basis for developing a highly efficient method for the green industrial production of indigo using engineered E. coli strains. Full article

Dictyophora rubrovolvata is highly regarded and increasingly cultivated in China for its nutritional value, unique taste, and medicinal properties. However, the chemical composition of fresh D. rubrovolvata is unclear. This study applied a comprehensive metabolomic analysis of D. rubrovolvata to characterize and compare the metabolite profiles and identify significantly differential metabolites from three geographical origins in China. Ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) combined with chemometrics was employed to conduct untargeted metabolomics analysis of fresh D. rubrovolvata samples collected from the Sichuan, Fujian, and Guizhou provinces in China. Among the 383 identified metabolites, lipids and organic acids were the predominant classes. There were notable variations in metabolite composition across the three geographical areas. The Sichuan (SC) group showed a high concentration of phospholipids, the Guizhou (GZ) group was characterized by specific oxidized lipids and bioactive benzenoids, and the Fujian (FJ) group showed elevated levels of the antioxidant ergothioneine. We identified 17 unique metabolites, including tryptophol, 12-oxophytodienoic acid, and various fatty acid derivatives, which may act as significantly differential metabolites for different origins. Analysis of KEGG enrichment indicated that the main metabolic pathways involved were tryptophan metabolism, glycerophospholipid metabolism, and phenylpropanoid biosynthesis. Full article

Benign prostatic hyperplasia (BPH) is an age-related disorder increasingly linked to chronic inflammation and redox imbalance, yet its systemic oxidative and nitrosative profile remains insufficiently characterized. In this cross-sectional study, fasting serum samples were collected from 47 men with clinically confirmed BPH scheduled for transurethral resection of the prostate and 40 healthy controls. We assessed antioxidant status (thiols, total antioxidant capacity), lipid peroxidation (malondialdehyde, 4-hydroxynonenal), protein nitration (3-nitrotyrosine), glycoxidation markers (Amadori products, advanced glycation end products (AGE)-associated fluorescence), and tryptophan metabolism indices (tryptophan, kynurenine, N′-formylkynurenine). Compared with controls, BPH patients showed significantly lower antioxidant capacity and thiol levels, together with increased lipid peroxidation and protein nitration. AGE-associated fluorescence was modestly elevated, whereas Amadori products and advanced oxidation protein products did not differ significantly. Tryptophan metabolism was markedly altered, with lower tryptophan and higher kynurenine and N′-formylkynurenine, indicating activation of the kynurenine pathway. After false discovery rate correction, most redox biomarkers remained significant. Multivariable logistic regression confirmed independent associations of lipid peroxidation, nitrosative stress, and kynurenine pathway activation with BPH after adjustment for age and metabolic parameters. These findings support a role for systemic oxidative and inflammatory mechanisms in BPH pathophysiology, although confirmation in age-matched and longitudinal studies is needed. Full article

Objectives: To overcome the limitations of invasive diagnostic approaches for ulcerative colitis (UC) diagnosis, this study integrates liquid chromatography–mass spectrometry (LC–MS)-based serum metabolomics with mucosal transcriptomics to elucidate the interplay between systemic metabolic perturbations and neuroendocrine signaling in UC pathogenesis. Methods: Serum metabolites and mucosal differentially expressed genes (DEGs) were identified through multi-omics profiling. Key neurotransmitter receptor-related genes (NRRGs) were prioritized using three machine learning algorithms: LASSO, Random Forest, and SVM-RFE. A three-gene diagnostic nomogram was developed and rigorously validated across multiple independent cohorts (GSE48958, GSE73661) using receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA). Results: The integrated analysis revealed 334 dysregulated metabolites and 3093 DEGs, both converging on the serotonergic synapse pathway. Specific molecular alterations were uncovered, including tryptophan depletion linked to the downregulation of SLC6A4, concomitant with abnormal serotonin accumulation and PTGS2-mediated inflammatory responses. The three-gene signature, HTR3C, RPS6KA6, and NETO2, formed a highly robust diagnostic model, achieving an area under the ROC curve (AUC) exceeding 0.96 in both the training cohort and external validation sets. Conclusions: This multi-omics study delineates a neuroimmune mechanism in UC centered on dysregulation of the serotonergic synapse. The resulting three-gene nomogram identifies a candidate biomarker signature that demonstrates strong discriminative potential; however, given the exceptionally high performance metrics, these findings should be interpreted as a preliminary diagnostic framework rather than a clinically validated tool, and its efficacy relative to standard markers like CRP or fecal calprotectin requires further investigation in prospective real-world cohorts. Nonetheless, this study provides critical mechanistic insights into gut–brain axis dysfunction in UC. Full article

Background/Objectives: Recently, a randomized clinical trial evaluated whether a six-month probiotic administration could reduce symptom severity in preschool children with Autism Spectrum Disorders (ASD), with (GI) or without (NGI) gastrointestinal symptoms. Significant positive changes were observed only in NGI children. A second explorative study on children prior to intervention identified a fecal metabolome fingerprint associated with ASD severity. Building on these findings, the present study aimed to assess whether metabolomics could monitor changes in ASD severity following probiotic administration using a subset of samples from the same trial. Second, this study aimed to identify fecal metabolites to be monitored in children to predict whether their autism severity may decrease after probiotic or placebo treatment. Methods: Evaluations of the fecal metabolome and microbiota could be completed on 57 children before and after a double-blind administration of a probiotic mixture or a placebo. Results: In NGI children the probiotic was found to influence the concentration of the amino acids aspartate, leucine, tryptophan, and valine, together with nicotinate and the short chain fatty acids acetate, butyrate, isobutyrate, and propionate. Lactobacilli and Sutterella showed significant changes in response to probiotic administration (p < 0.05). Acetate, 4-hydroxyphenyl, galactose, proline, and tyramine were identified as key fecal metabolites for prediction purposes. Conclusions: The present exploratory analysis, despite the small sample size, suggests that fecal metabolomics may provide a useful approach for monitoring and potentially for predicting changes in ASD severity following probiotics administration. Full article

Background: Gut microbiome-derived metabolites, particularly short-chain fatty acids (SCFA) and tryptophan derivatives, are central mediators of the gut–brain axis. This ex vivo study assessed how nutritional interventions impact such metabolites during early life, a critical period for neurodevelopment. Methods: The effects of galacto-oligosaccharides (GOS), nutrient blends (vitamins, minerals and amino acids) and their combinations were evaluated in the gut microbiomes of infants (2–4 months, n = 6) and young children (2–3 years old, n = 6) using the ex vivo SIFR^® technology. Results: Baseline microbiome composition was age-dependent, with infants displaying lower α-diversity and greater interpersonal variability. After ex vivo incubation, nutrient blends increased the propionate/butyrate ratio and branched-chain fatty acids in young children and elevated several B-vitamins and amino acid-derived metabolites, including indole-3-carboxaldehyde, imidazoleacetic acid and pipecolinic acid. Combining nutrient blends with GOS exhibited potential synergistic effects on propionate (infants) and 2-hydroxyisocaproic acid (HICA, both age groups). GOS strongly stimulated Bifidobacteriaceae and increased metabolites linked to bifidobacterial metabolism like acetate, HICA, N-acetylated amino acids, aromatic lactic acids and acetylagmatine; in young children, butyrate and γ-aminobutyric acid (GABA) also increased. Conclusions: Combinations of GOS with nutrient blends impacted microbiome-derived metabolites associated with the gut–brain axis, with potential synergistic increases of metabolites with emerging roles in neurodevelopment, including GABA, acetylagmatine and HICA. Despite shared bifidogenic effects, differences between age groups indicate that microbiome maturity may influence responses to nutritional intervention. Future clinical studies are needed to determine whether these metabolite changes translate into neurodevelopmental benefits in vivo. Full article

Pharmacological chaperones (PCs)—small molecules that normalize the 3D structure of mutant protein molecules—are promising substances for pharmacological treatment of grave hereditary pathologies. In this study, possible chaperone-like effects of the Fe(II) with tris(1-pyrasolyl)methane complex, [Fe(TPM)₂]Cl₂, on the mutant 447R form of mouse tryptophan hydroxylase 2 (TPH2) in vitro and in vivo were investigated. The experiments were carried out on Balb/c mice homozygous for the mutant TPH2. This complex in concentrations of 0.01, 0.05 and 0.1 mM markedly increased the temperature (T₅₀) and free energy (ΔG) of the mutant TPH2 thermal denaturation in vitro. Seven intramuscular administrations of 30 and 60 mg/kg of [Fe(TPM)₂]Cl₂ markedly increased the TPH2 activity in the midbrain of Balb/c mice. This increase in the TPH2 activity was not accompanied with an increase in the Tph2 gene mRNA and TPH2 protein levels. It is the first demonstration of chaperone-like activity of [Fe(TPM)₂]Cl₂. This complex is a promising chemical for correction of genetic alterations in TPH2 and the associated hereditary psychic disorders. Full article

Immune checkpoint inhibitors (ICIs) have revolutionized the therapeutic landscape for hepatocellular carcinoma (HCC); however, a considerable proportion of patients do not achieve durable clinical benefits. This highlights the need for reliable predictive biomarkers, which are currently lacking. The accumulated evidence supports a relevant role of the gut–liver axis in modulating immunotherapy outcomes, and several studies have identified distinct microbial features associated with either responders or non-responders. Responders to immunotherapy frequently present with higher microbial diversity and enrichment of beneficial taxa, whereas the expansion of pro-inflammatory and pathogenic bacteria has been associated with primary resistance and increased treatment-related toxicity in non-responders. However, the available findings remain heterogeneous across cohorts, likely owing to differences in geography, diet, liver disease etiology, treatment regimens, and microbiome analytical methods. Machine-learning models integrating metagenomic and metabolomic data have shown encouraging results in defining microbial signatures associated with treatment outcomes, although variability among cohorts currently limits their clinical applicability and generalizability. Beyond microbial taxonomic composition, microbiota-derived metabolites—such as short-chain fatty acids, bile acids, inosine, and tryptophan catabolites—appear to play a crucial role in shaping the tumor microenvironment and host immune responses, thus representing additional candidate biomarkers, also due to the relative ease of their measurement. Finally, microbiota-targeted interventions are emerging as potential strategies to enhance immunotherapy efficacy. Overall, the gut microbiome and its metabolic activity represent promising tools, albeit still under investigation, for patient stratification and personalized management in HCC treated with ICIs. Therefore, this review aims to summarize and critically discuss the current evidence on gut microbiota-derived biomarkers of response and resistance to ICIs in HCC, with particular focus on microbial composition, microbiota-related metabolites, and emerging microbiome-based therapeutic strategies. This narrative review provides an updated overview of the role of gut microbiota as both a biomarker and a therapeutic target in patients with hepatocellular carcinoma (HCC) receiving immune checkpoint inhibitor (ICI) therapy. Full article

Schizophrenia spectrum disorders (SSD) are severe psychiatric conditions characterized by disturbances in cognition, emotion, and behavior, with increasing evidence suggesting an involvement of the gut microbiome in their pathophysiology. This PRISMA-informed structured review synthesizes 114 studies using a taxa-centered framework that maps microbial changes across SSD stages and phenotypes and serves as a structural basis for identifying cross-study patterns. Across heterogeneous cohorts, convergent alterations include depletion of short-chain fatty acid (SCFA)-producing taxa (including Faecalibacterium, Roseburia, and Coprococcus) and enrichment of potentially pro-inflammatory and fermentative taxa (such as Proteobacteria, Enterobacteriaceae, Streptococcus, Collinsella, and Desulfovibrio). These taxonomic patterns suggest potential functional alterations, including reduced SCFA availability. Reduced abundance of butyrate-producing taxa has been associated with impaired intestinal barrier function and increased microbial translocation (e.g., lipopolysaccharide), which may contribute to the activation of immune pathways, including Toll-like receptor 4 signaling and elevated inflammatory markers such as IL-6 and TNF-α. Additional alterations reported across studies include changes in lactate metabolism, bile acid profiles, aromatic amino acid metabolism, and the tryptophan-kynurenine pathway. These pathways may interact with neurobiological processes relevant to SSD, including glutamate-GABA balance, NMDA receptor function, microglial activation, and synaptic regulation, although much of the current evidence remains associative. Multi-kingdom studies and fecal microbiota transplantation models provide further support for the functional relevance of these observations, though causal relationships remain to be fully established. Overall, SSD-associated dysbiosis appears to reflect ecosystem-level metabolic alterations rather than isolated taxonomic abnormalities, supporting a Microbiota–Gut–Immune–Glia conceptual framework and highlighting the gut ecosystem as a potential therapeutic target. Full article

While L-tryptophan is a precursor of plant growth regulators, its effects on secondary metabolism, amino acid profile and cell wall organization in flax callus remain underexplored. This study aimed to optimize flax callus shaken cultures and evaluate the impact of L-tryptophan (0.1 mM and 1 mM) on structural properties of plant cell walls in tested callus using Fourier transform infrared spectroscopy. The impact of L-tryptophan on callus proliferation and metabolism was also determined, because amino acids (among them L-tryptophan) can promote the growth of callus. The results showed that 1 mM L-tryptophan is an effective elicitor, which stimulates flax callus to accumulate larger amounts of bioactive compounds, especially carotenoids and polyphenols, than control callus cultured without L-tryptophan. A lower concentration of L-tryptophan (0.1 mM) slightly improved the level of determined secondary metabolites (except flavonoids). The effect of L-tryptophan on polymers in plant cell walls was investigated. The data confirm that the plant cell wall is a dynamic structure, capable of remodelling in response to growth conditions and external agents. L-tryptophan (0.1 and 1 mM) reduced cellulose levels and induced structural changes in cellulose compared to the untreated control. The structural analyses also suggested a decrease in lignin level and increase in pectin amounts in flax callus after tryptophan addition in comparison to control callus. The results may reflect the relationship between tryptophan and auxins (which are derived from tryptophan) and confirm the role of these metabolites in shaping the structure of the plant cell wall. In fact, an increase in tryptophan level was confirmed in flax callus in tested experimental conditions (supplementation of cultures with both doses of L-tryptophan). These findings have practical significance, because L-tryptophan is also used as a fertilizer or component of fertilizers in plant cultivation. Full article

The role of amino acid disturbances in the mother–fetus system remains poorly understood, despite their critical involvement in gestational diabetes mellitus (GDM), fetal macrosomia (FM) and offspring metabolic programming. This study included 62 mother–newborn dyads stratified by GDM and FM status. An analysis of the association of amino acids with clinical parameters was performed using the Spearman test. Amino acid markers of GDM were identified using the mutual information index and the Mann–Whitney test. A random forest method was used to identify amino acid markers, with the SHAP value used to estimate the contribution of each amino acid. In maternal serum, GDM was associated with significantly lower levels of glycine, 1-methylhistidine, γ-aminobutyric acid, lysine, and tryptophan. Umbilical cord serum from GDM pregnancies showed reduced concentrations of glutamine, glycine, asparagine, methionine, and proline. In amniotic fluid, GDM with FM was characterized by elevated lysine and 1-methylhistidine. Cord blood exhibited increased lysine, proline, leucine, and allo-isoleucine, while amniotic fluid showed low homocitrulline, asparagine, and lysine, together with high histidine. Fetal weight correlated directory with lysine and isoleucine and inversely with homocitrulline. Pathway analysis linked maternal serum markers to disturbances in biotin, glutamate, and carnitine metabolism, whereas cord blood markers involved broader alterations in amino acid, purine, and amino sugar metabolism. In amniotic fluid from GDM with FM, the methylhistidine pathway was specifically enriched, suggesting changes in neonatal muscle protein turnover. GDM induces distinct alterations in the amino acid profiles of all three compartments, and the combination with FM yields unique metabolic signatures. These findings identify candidate biomarkers for prediction of GDM and its complications and point to potential targets for metabolic intervention. Full article

Tyrosinase promotes excessive deposition of melanin, which may lead to severe skin diseases. Passiflora edulis f. edulis seeds have been reported to be rich in diverse bioactive constituents exhibiting potential tyrosinase inhibitory activity. However, the principal bioactive constituents responsible for tyrosinase inhibitory activity and its underlying mechanisms remain largely unclear. Therefore, this study aimed to: (1) optimize SC-CO₂ extraction of Passiflora edulis f. edulis seed oil (PFSO) for maximum yield and bioactive preservation; (2) comprehensively characterize its physicochemical and phytochemical profile; (3) elucidate the tyrosinase inhibition mechanism through kinetic, spectroscopic, and computational approaches; and (4) validate its safety, antioxidant, and anti-pigmentation efficacy in a zebrafish model. PFSO exhibited a yield of 24.96%, with a high content of unsaturated fatty acids (88.03%, mainly linoleic acid at 74.40%). The oil inhibited tyrosinase via a reversible mixed-type mechanism (IC₅₀ = 1.12 mg/mL). Fluorescence spectroscopy and molecular docking revealed that linoleic acid binds to LYS180 and β-sitosterol binds to TYR78, mainly driven by hydrogen bonding and hydrophobic interaction, which changed the microenvironment of tryptophan residues and indicated static quenching. Further validation experiments revealed that the major constituent, linoleic acid, exhibited only weak inhibitory activity against tyrosinase (IC₅₀ = 29.44 mg/mL), whereas the key component β-sitosterol markedly suppressed tyrosinase activity (IC₅₀ = 46.43 μg/mL). In vitro assays demonstrated PFSO’s significant efficacy in reducing the melanin content and tyrosinase activity in α-MSH-stimulated B16F10 murine melanoma cells. In vivo experiments in zebrafish that received dietary supplementation with PFSO confirmed that PFSO (≤5 mg/mL) reduced ROS production, suppressed melanin deposition, inhibited tyrosinase activity, and downregulated the expression of melanogenesis-related genes (TYR, TYRP1, TYRP2, MITF). This study provides, for the first time, a comprehensive elucidation of PFSO’s potential as a natural tyrosinase inhibitor, integrating extraction optimization, multicomponent characterization, multimodal inhibition analysis, and in vivo validation. Full article

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disorder with a high incidence of anxiety and depression. However, the underlying mechanisms of these symptoms remain to be fully elucidated. This study investigated the effects and mechanisms of a 20% ethanolic extract of Petasites japonicus leaves (EPJ) on dextran sulfate sodium (DSS)-induced colitis and depression-like behaviors. The physiological compounds identified in the EPJ were citric acid, chlorogenic acid, caffeic acid, fukinolic acid, 3,5-dicaffeoylquinic acid, quercetin 3-O-β-D-glucose-6″-acetate, 4,5-dicaffeoylquinic acid, kaempferol-3-O-(6″-acetyl)-β-glucopyranoside, and pedunculoside. EPJ significantly alleviated DSS-induced colitis, as evidenced by improvements in body weight loss (87.41% vs. 76.02% in the DSS group), colon length (5.75 vs. 4.34 cm), intestinal permeability (52.80 vs. 163.01 μg/mL), and myeloperoxidase (MPO) activity (0.24 vs. 0.67 U/mg) (p < 0.05). Histological analysis further confirmed recovery of goblet cells and attenuation of muscle layer thickening. EPJ also reversed DSS-induced gut microbiota dysbiosis and contributed to the restoration of microbial homeostasis. Behavioral assessments showed that EPJ effectively ameliorated depression-like behaviors. EPJ improved antioxidant systems in colon and brain tissues by modulating malondialdehyde (MDA) levels and reduced glutathione (GSH) and superoxide dismutase (SOD) activity. EPJ further upregulated tight junction protein expression and suppressed TLR4/NF-κB inflammatory pathway activation in both colon and brain tissues. Moreover, EPJ modulated serum stress-related hormones, normalized hypothalamic–pituitary–adrenal (HPA) axis dysregulation, regulated the BDNF/TrkB signaling pathway, and modulated tryptophan–kynurenine metabolism. Collectively, these findings suggest that EPJ exerts protective effects against DSS-induced colitis and depression-like behaviors. Full article