Establishment of an immunoassay for detection of melatonin and 2-mydroxymelatonin based on computer-aided design.

Preserved circadian rhythms reflected by dim light melatonin onset in patients with KLS.

African American women carry a disproportionate burden of cardiometabolic disease (CMD) risk and experience higher rates of sleep disturbances compared to other racial and ethnic groups. Sleep and the sleep-regulating hormone melatonin play key roles in modulating inflammation, a biological pathway central to CMD. Chronic exposure to racism and discrimination may exacerbate stress, disrupt sleep and melatonin rhythms, and elevate inflammatory responses, further heightening CMD risk. The purpose of this pilot study is to evaluate the effects of a race-based stress reduction intervention-Resilience, Stress, and Ethnicity (RiSE)-on sleep quality and dim-light melatonin onset (DLMO) as primary outcomes, and to examine inflammation as a secondary outcome among older African American women with CMD risk. Leveraging an ongoing randomized controlled trial (RCT) (R01AG081251), this embedded pilot RCT will randomize 32 women to either the RiSE intervention or an attention control health education program, both delivered via eight weekly online sessions. Sleep quality will be assessed using validated questionnaires and wrist-worn ActiGraph devices for seven nights. DLMO will be determined from seven salivary samples collected around habitual bedtime, and salivary cytokines will be measured for inflammation. All measures will be obtained pre- and post-intervention. This pilot study is the first to examine an integrative, race-based stress reduction intervention targeting sleep and melatonin rhythms in this population. Findings will inform future mechanistic studies and the development of nurse-led strategies to mitigate the adverse physiological consequences of discrimination-related stress on sleep and cardiometabolic health among African American women.

Molecular insights into melatonin-mediated stress tolerance in Dendrobium: Integrating antioxidant defense, hormonal networks, and omics approaches.

Wampee (Clausena lansium) is a tropical and southern subtropical fruit tree whose productivity is limited by low-temperature stress (LTS). This study investigated the physiochemical and ‌molecular mechanisms by which melatonin (MLT) enhances chilling tolerance in wampee. MLT treatment improved membrane stability and reduced oxidative damage by enhancing antioxidant capacity and osmotic adjustment. Metabolomic and transcriptomic analyses revealed that differentially expressed genes and metabolites were primarily associated with flavonoid biosynthesis and starch and sucrose metabolism pathways. Eleven key candidate genes were identified, including sucrose synthase, granule-bound starch synthase, trehalose-6-phosphate synthase, chalcone-flavonone isomerase, flavonoid 3',5'-hydroxylase, and UDP-glycosyltransferase. MLT treatment also increased soluble carbohydrate levels, such as sucrose and fructose, and enhanced sucrose phosphate synthase activity. Transcription factors ClbHLH2 and ClNAC1 enhanced wampee's cold tolerance by activating the sucrose-biosynthetic genes ClSUS2 and ClSPS1, respectively. These findings provide insights into the molecular and physiological mechanisms underlying wampee adaptation to LTS and highlight MLT as a potential tool to improve wampee's cold tolerance.

Association of ADHD symptoms with the interactions within and between the HPA axis and melatonin system characterized by hair-based biomarkers.

ABSTRACT Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease primarily characterized by symmetrical synovial inflammation, leading to joint swelling, pain, and progressive cartilage and bone destruction. Unfortunately, the clinical treatment of RA still faces numerous challenges. Although melatonin (MT), the circadian rhythm hormone, is known to relieve the pathological process of RA, the underlying mechanism remains poorly understood. Herein, we assess the impacts of MT on collagen or K/BxN serum-induced arthritis (two well-established models of RA) and confirm its excellent therapeutic effect. Mechanistically, MT activates MTNR1A (melatonin receptor 1A) to promote mitophagy for the elimination of reactive oxygen (ROS) and leaked mitochondrial DNA triggered by damaged mitochondria, which in turn limits NLRP3 (NLR family pyrin domain containing 3) inflammasome activation and pro-inflammatory cytokine release. Mice with deletion of the autophagy-related gene Atg5 in myeloid cells (atg5 fl/fl Lyz2/LysM-cre) barely display any benefits of MT in K/BxN serum-induced arthritis. Our results indicate that mitophagy promoted by MT is essential to deactivate NLRP3 inflammasome and alleviate the development of arthritis, which provides a candidate for the treatment of RA. Abbreviations: 3-MA: 3-methyladenine; ACP5/TRAP: acid phosphatase 5, tartrate resistant; ANOVA: analysis of variance; ATG5: autophagy releated 5; ATP: adenosine triphosphate; BMD: bone mineral density; BMDMs: bone marrow derived macrophages; BV:TV: bone volume to tissue volume; CASP1: caspase 1; CYCS: cytochrome c; DNM1L/DRP1: dynamin 1 like; EtBr: ethidium bromide; FCCP: carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone; GSDMD: gasdermin D; IL1B/IL-1β: interleukin 1 beta; IL18: interleukin 18; LPS: lipopolysaccharide; MT: melatonin; MTNR1A: melatonin receptor 1A; MTNR1B: melatonin receptor type 1B; MFF: mitochondrial fission factor; mtROS: mitochondrial reactive oxygen species; mt-DNA: mitochondrial DNA; NAC: N-acetylcysteine; NT-GSDMD: N-terminal gasdermin D; NLRP3: NLR family pyrin domain containing 3; Ox-mtDNA: oxidized mitochondrial DNA; PINK1: PTEN induced kinase 1; PRKAA/AMPK: protein kinase AMP-activated catalytic subunit alpha; PRKN: parkin RBR E3 ubiquitin protein ligase; PYCARD/ASC: PYD and CARD domain containing; RA: rheumatoid arthritis; ROS: reactive oxygen; SD: standard deviation; SQSTM1/p62: sequestosome 1; Tb.N: trabecular number; Tb.Th: trabecular thickness; TNF/TNF-α: tumor necrosis factor; ULK1: unc-51 like autophagy activating kinase 1.

While red light positively regulates crop physiology in agriculture, the application of light signaling-based red-emitting carbon dots (RCDs) to enhance field crop stress resistance remains underexplored. RCDs were hydrothermally synthesized and foliarly applied to sweetpotato under drought stress (10% PEG). Their photoluminescence (PL) activated the root melatonin (MT) biosynthesis gene IbASMT1, elevating MT levels by ∼2.5-fold. This MT surge upregulated the K+ regulator gene IbSKOR through IbGCN5-mediated histone acetylation; IbSKOR overexpression confirmed its drought-tolerance role. Critically, the MT inhibitor p-chlorophenylalanine or PL-quenched RCDs abolished this effect, confirming PL's essentiality. The core IbASMT1-MT-IbGCN5 module fine-tuned K+ homeostasis by upregulating IbAKT1 and IbSKOR. Our findings identified RCDs as effective photosignal modulators for crop drought tolerance via an MT-dependent epigenetic pathway, providing a novel carbon dot-based agro-technology strategy.

Oxidative degradation of melatonin in solution and solid-state pharmaceutical blends: HPLC-HRMS/MS degradant characterization, metal-mediated acceleration and EDTA mitigation.

The clinical failure of infected bone repair is primarily due to the inability of conventional scaffolds to simultaneously eradicate resilient biofilms and orchestrate the subsequent bone regeneration within the hostile inflammatory microenvironment. In this study, we developed a NIR assisted composite scaffold based on a 3D printed polycaprolactone (PCL) framework coated with a gelatin methacryloyl (GelMA) hydrogel containing copper hydroxyphosphate (CuHP) and melatonin (MT). Under near-infrared (NIR) irradiation, the scaffold exhibited enhanced antibacterial activity against Staphylococcus aureus via photothermal effects. The presence of MT was associated with reduced local inflammation and increased M2 like macrophage markers in vivo, although direct immunomodulatory mechanisms were not proven. The scaffold supported osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) in vitro and promoted new bone formation in an acute rat model of infected femoral defect. This study presents a promising combination system.

Cadmium (Cd) is a prevalent and toxic heavy metal widely present in soils. Cotton (Gossypium hirsutum L.), which readily accumulates Cd, exhibits inhibited seed germination under Cd stress. Melatonin (MT), a potent indoleamine antioxidant, has been demonstrated to facilitate seed germination under adverse conditions, but its regulatory mechanisms in cotton under Cd stress remain unclear. In this study, cotton seeds of the cultivar 'Nongda 601' were used to investigate the effects of exogenous MT on germination characteristics, antioxidant enzyme activities, and hormone levels under Cd stress. Experimental treatments included a control (CK), MT treatment, Cd treatment, and a combined Cd + MT treatment (CM). Transcriptome sequencing was further conducted to elucidate the underlying mechanisms. Cd stress significantly inhibited cotton seed germination, reduced amylase activity, and increased starch accumulation. It also decreased antioxidant enzyme activities while increasing reactive oxygen species (ROS) and malondialdehyde (MDA) contents. In addition, Cd stress increased IAA, ABA, and endogenous MT contents, while decreasing GA3 and ZR levels. Exogenous MT significantly enhanced amylase and antioxidant enzyme activities, decreased ROS, MDA, and starch contents, and modulated hormone levels by increasing IAA, GA3, ZR, and endogenous MT, while decreasing ABA content. Transcriptome analysis indicated that MT upregulated the expression of antioxidant-related genes under Cd stress, including SODA, FSD, CAT2, and pod. Additionally, exogenous MT alleviated Cd toxicity by regulating hormone signal transduction and the phenylpropanoid biosynthesis pathway. Exogenous MT alleviates Cd-induced inhibition of cotton seed germination by enhancing antioxidant capacity, promoting starch mobilization, and rebalancing hormone signaling, while modulating phenylpropanoid metabolism. These findings provide a theoretical foundation for improving cotton cultivation in Cd-contaminated soils.

Soil contamination by microplastics (MPs) and heavy metals (HMs), particularly cadmium (Cd), poses an emerging threat to agricultural sustainability, food safety, and human health. Although the individual effects of MPs and Cd on crop performance have been widely investigated, their interactive impacts on rice remain poorly understood. Biochar (BC) and melatonin (MT) have recently attracted attention for their capacity to alleviate HM toxicity and abiotic stress in plants; however, their combined potential to mitigate MP-Cd co-stress has not yet been explored. This study aimed to evaluate the individual and enhanced effects of BC and MT on rice growth, physiological and molecular responses, Cd bioavailability, and soil properties under MP-Cd co-contamination. Exposure to Cd (20mg kg⁻¹) and MPs (1%) significantly inhibited rice growth and productivity by inducing oxidative stress, enhancing Cd uptake and accumulation, suppressing chlorophyll biosynthesis, and impairing water and nutrient acquisition. In contrast, the combined application of BC (2%) and MT (100 µM) markedly alleviated these adverse effects and outperformed individual amendments. Co-application substantially increased chlorophyll content (82%), leaf relative water content (48.47%), antioxidant enzyme activities (57.84-99.42%), proline accumulation (49.21%), and endogenous melatonin (EM) levels (48.35%). At the molecular level, BC + MT treatment upregulated antioxidant-related genes (OsAPx6, OsCAT, OsPOD, and OsSOD), the proline biosynthesis gene OsP5CS, and the MT biosynthesis gene OsCOMT, while significantly downregulating Cd transporter genes (OsNRAMP1 and OsHMA3). Furthermore, this combined treatment reduced soil Cd bioavailability and Cd accumulation in rice tissues, while improving soil fertility by increasing nitrogen (N), phosphorus (P), potassium (K), and soil organic carbon (SOC). This study provides the first evidence that the combined application of BC and MT effectively mitigates the detrimental effects of simultaneous MP and Cd contamination in rice. The enhanced physiological, molecular, and soil-level improvements induced by BC and MT collectively enhance rice growth and productivity under MP-Cd stress. These findings highlight a promising, integrated remediation strategy to manage co-pollution of MPs and HMs in agricultural soils, with important implications for sustainable crop production and food security.

Melatonin buffers antioxidant defense but only partially sustains photosynthesis under combined abiotic stresses in Chlamydomonas reinhardtii.

Insomnia is a common physiological and psychological disorder characterized by difficulty falling or staying asleep, which negatively impacts daily functioning. Oral melatonin (MEL) is commonly used to treat insomnia and other sleep-related disorders. However, MEL has low bioavailability due to extensive first-pass metabolism and poor aqueous solubility, and its onset of action is slow. Dissolving microneedles (MNs) represent a promising minimally invasive approach to overcome these drawbacks by enhancing transdermal drug permeation and enabling systemic delivery while circumventing the gastrointestinal tract. In this study, different dissolving MN arrays composed of hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP) were fabricated using solvent casting and vacuum-assisted micromolding techniques. Among the tested formulations, 10% (w/v) HPMC and 10% (w/v) PVP-based formulation demonstrated favorable mechanical strength and insertion capability. MEL was successfully loaded into the MN shafts of the lead formulation with a drug loading of 1.83 ± 0.05 mg per MN patch. FTIR and DSC analyses confirmed the molecular dispersion of MEL within the polymeric matrix. In vitro release studies revealed rapid dissolution with approximately 87% of melatonin released within 60 min, whereas ex vivo tests on porcine skin showed complete microneedle dissolution within 3 min. In vivo pharmacokinetic studies in mice revealed rapid systemic absorption following MEL MN application and a prolonged elimination half-life. MEL also penetrated the central nervous system (CNS), reaching a Cmax of 6.08 ± 3.65 ng/g and exhibiting a prolonged residence time in the brain. Taken together, MEL MNs hold promise as a viable transdermal delivery modality. However, further investigation is warranted to comprehensively evaluate their therapeutic efficacy.

Melatonin (MEL) modulates the circadian rhythm and has been studied as a preventive measure against delirium, especially in intensive care unit (ICU) patients, but the current findings are conflicting. We performed a pairwise dose‒response meta-analysis of randomized controlled trials (RCTs) followed by meta-regression and trial sequential analysis to assess the ability of MEL or ramelteon (RAL) to prevent delirium in the ICU. We evaluated the certainty of the evidence via GRADE and the credibility of the subgroup analysis via the ICEMAN tool. We identified 24 studies that included 3680 participants. Compared with placebo, melatoninergic agonists reduce the incidence of delirium (0.77 [0.62,0.94], primary analysis of 18 studies), with superior effects in the MEL group (RR 0.77 [0.62, 0.97]) and in surgical-type ICU (RR 0.64 [0.48, 0.87]). We found a nonlinear dose‒response relationship between the cumulative dose of MEL and the RR of delirium, suggesting an optimal cumulative dose of 22mg of MEL (RR 0.732 [0.599, 0.895]). Subgroup and meta-regression analyses revealed a significant effect of intervention duration on the risk of delirium, with a superior effect in the subgroup with ≥ 7days of intervention (RR 0.73 [0.60, 0.90]). Melatoninergic agonists did not affect 28-30-day or ICU mortality or the incidence of adverse effects. Melatoninergic agonists showed a clinically relevant trend based on the minimal clinically important difference (MCID) to reduce the ICU length of stay (LOS) (MD:-0.74 [-1.60, 0.12], MCDI -0.113 [1.846, -2.073]), hospital LOS (MD -0.33 [-1.91, 1.25], MCID -0.134 [1.833, -2.108]) and length of mechanical ventilation (MV) (MD -0.50 [-1.16, 0.16], MCID -0.2146 [1.744, -2.173]). Compared with placebo, they may increase the time to the onset of delirium (MD 0.76 [0.43, 1.09]), but with very-low certainty. Our findings indicate that melatoninergic agonists probably reduce the risk of delirium in ICU patients, especially those treated with MEL, in surgical-type ICUs and for durations equal to or longer than 7days, with an optimal cumulative dose of 22mg. Additionally, they appear to be safe while offering potential benefits in reducing ICU length of stay and duration of mechanical ventilation. However, the magnitude of effect was modest, with low-certainty evidence and moderate heterogeneity, and these findings should therefore be interpreted with caution.

Timed melatonin administration increases territorial but not non-territorial aggression in female Siberian hamsters.

Brassica napus L. is one of the world's most important edible oil crops, and its productivity is severely affected by abiotic stresses, including heavy metal contamination. Vanadium (V) toxicity disrupts plant growth, impairs photosynthesis, and induces excessive reactive oxygen species (ROS) accumulation. Melatonin (MT) is an emerging plant regulatory molecule known to enhance stress tolerance; however, its physiological and transcriptomic roles in mitigating V-induced toxicity in B. napus remain poorly understood. In this study, B. napus seedlings were subjected to four treatments: control (CK), MT (100 µM), V (100mg L⁻¹), and MT + V (MTV). V stress significantly inhibited seedling growth, biomass accumulation, chlorophyll content, chlorophyll fluorescence (Fv/Fm), and water status, while increasing oxidative damage and ROS accumulation. MT supplementation markedly alleviated V-induced phytotoxicity by improving growth performance, chlorophyll accumulation, antioxidant enzyme activities (POD, CAT, and APX), and ROS scavenging capacity. MT treatment also reduced overall V accumulation in seedlings under V stress conditions. Transcriptomic analysis identified numerous differentially expressed genes (DEGs) associated with stress responses, antioxidant regulation, photosynthesis, and phenylpropanoid biosynthesis. Weighted Gene Co-expression Network Analysis (WGCNA) identified four key co-expression modules (turquoise, blue, brown, and yellow) strongly associated with MT-mediated stress responses. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed significant enrichment of genes involved in phenylpropanoid biosynthesis, glutathione metabolism, antioxidant defense, and transporter-related pathways. Our findings demonstrate that MT alleviates V-induced toxicity in B. napus through coordinated physiological and transcriptomic regulation involving antioxidant defense, photosynthetic protection, and stress-responsive metabolic pathways. This study provides new insight into the molecular mechanisms underlying MT-mediated heavy metal stress tolerance and highlights the potential application of MT for improving crop resilience under vanadium-contaminated conditions.

Melatonin orchestrates cAMP-PKA signaling to alleviate zearalenone-impaired the estradiol synthesis in mammal ovary.

Melatonin safeguards embryo and blastoid development against oxybenzone toxicity via a mitochondrial-linked NAD+ and glucose metabolic axis.

Flavonoids are essential secondary metabolites that contribute to fruit nutritional quality and stress adaptation. Jujube (Ziziphus jujuba Mill.) accumulates abundant flavonoids; however, the regulatory mechanisms by which melatonin (MT) modulates flavonoid biosynthesis remain poorly understood. In this study, exogenous MT treatment markedly promoted flavonoid accumulation in jujube leaves and triggered dynamic changes in endogenous MT levels, implying a regulatory function of MT in this process. Transcriptomic and correlation analyses identified ZjMYB1 as a key MT-responsive regulator strongly associated with flavonoid accumulation. Functional characterization revealed that silencing ZjMYB1 significantly decreased flavonoid content and downregulated genes in the phenylpropanoid pathway, whereas its overexpression enhanced flavonoid accumulation in jujube and heterologous systems. ZjMYB1 directly activated the key structural genes ZjF3H and ZjFLS by binding to MYB cis-elements in their promoters. Furthermore, the MT-responsive transcription factor ZjERF34 was identified as an upstream regulator of ZjMYB1. ZjERF34 directly targets the ZjMYB1 promoter to enhance its transcription, as demonstrated by Y1H, GUS staining, and dual-luciferase assays, establishing a hierarchical ERF-MYB regulatory network. In addition, ZjMYB1 overexpression significantly enhanced salt tolerance, correlating with increased flavonoid accumulation and upregulation of stress-responsive genes. Collectively, our findings reveal a MT-ZjERF34-ZjMYB1-ZjF3H/FLS regulatory module that links hormonal signaling with flavonoid biosynthesis and abiotic stress responses, providing new insights and potential molecular targets for improving fruit quality and stress resilience in horticultural crops.