Melatonin Concentrations Research Articles

Dual sources of melatonin and evidence for different primary functions.

This article discusses data showing that mammals, including humans, have two sources of melatonin that exhibit different functions. The best-known source of melatonin, herein referred to as Source #1, is the pineal gland. In this organ, melatonin production is circadian with maximal synthesis and release into the blood and cerebrospinal fluid occurring during the night. Of the total amount of melatonin produced in mammals, we speculate that less than 5% is synthesized by the pineal gland. The melatonin rhythm has the primary function of influencing the circadian clock at the level of the suprachiasmatic nucleus (the CSF melatonin) and the clockwork in all peripheral organs (the blood melatonin) via receptor-mediated actions. A second source of melatonin (Source # 2) is from multiple tissues throughout the body, probably being synthesized in the mitochondria of these cells. This constitutes the bulk of the melatonin produced in mammals and is concerned with metabolic regulation. This review emphasizes the action of melatonin from peripheral sources in determining re-dox homeostasis, but it has other critical metabolic effects as well. Extrapineal melatonin synthesis does not exhibit a circadian rhythm and it is not released into the blood but acts locally in its cell of origin and possibly in a paracrine matter on adjacent cells. The factors that control/influence melatonin synthesis at extrapineal sites are unknown. We propose that the concentration of melatonin in these cells is determined by the subcellular redox state and that melatonin synthesis may be inducible under stressful conditions as in plant cells.

The Effect of Lemon Juice (Citrus limon L.) Treated with Melatonin on the Health Status and Treatment of K14HPV16 Mice.

Lemon is a fruit rich in antioxidant properties and has several health benefits, namely the reduction of skin edema and anticarcinogenic properties, which are due to its high content of bioactive compounds. Melatonin can improve and preserve the properties of lemon for longer and also has health benefits. The aim of this study was to evaluate the effects of oral administration of lemon juice after melatonin treatment on murinometric parameters of wild-type (WT) mice and transgenic mice carrying human papillomavirus (HPV). Two trials were performed for oral administration of the lemon extract compound: in drinking water and in diet. First of all, lemons were treated by immersion with melatonin at 10 mM. Then, lemons were squeezed, and the juice obtained was freeze-dried and stored to be subsequently added to drinking water or diet, according to the assay. Thus, mice were divided into eight groups in the drink assay (each with n = 5): group 1 (G1, WT, control), group 2 (G2, WT, 1 mL lemon), group 3 (G3, WT, 1.5 mL lemon), group 4 (G4, WT, 2 mL lemon), group 5 (G5, HPV16, control), group 6 (G6, HPV16, 1 mL lemon) group 7 (G6, HPV16, 1.5 mL lemon) and group 8 (G6, HPV16, 2 mL lemon). The diet assay was divided into four groups: group 1 (G1, WT, control), group 2 (G2, WT, 4 mL lemon), group 3 (G3, HPV16, control) and group 4 (G4, HPV16, 4 mL lemon). In the drink assay, the highest concentration of melatonin (308 ng/100 mL) was for groups 4 and 8, while in the food assay, there was only one concentration of melatonin (9.96 ng/g) for groups 2 and 4. Both trials lasted 30 days. During this time, body weight, food and water were recorded. Afterward, they were sacrificed, and samples were collected for different analyses. At the concentrations used, the lemon juice with melatonin had no adverse effects on the animals' health and showed a positive outcome in modifying weight gain and enhancing antioxidant activity in mice. Moreover, a reduction in the incidence of histological lesions was observed in treated animals. Further research is needed to better understand the effects of lemon extract on health and treatment outcomes in this animal model.

Melatonin Modulates Lipid Metabolism and Reduces Cardiovascular Risk in Apolipoprotein E-Deficient Mice Fed a Western Diet

Melatonin (MLT), a natural compound found in the animal and vegetable kingdom, participates in several physiological processes. MLT exerts antioxidant and anti-inflammatory activities, among others, but information about its action on lipid metabolism is still scarce. For this reason, mice deficient in apolipoprotein E (ApoE−/−) fed a Western diet (WD) were intragastrically treated with different concentrations of MLT (2 and 9 mg/kg) for 12 weeks. The lipid parameters were quantified, and, since links between cardiovascular risk and immune function and oxidative stress have been established, we also analyzed the population of leukocytes and the oxidative stress status. Although there was no change in the weight of the mice, a significant reduction in low-density lipoprotein cholesterol (LDL-C) was observed in mice treated with the higher concentration of MLT tested in this study. Additionally, an improvement in cardiovascular risk indexes was observed. A reduction in the hepatic total cholesterol (TC) and LDL-C levels was also observed in the treated mice. Finally, a decrease in leukocytes and lymphocytes in particular, as well as an increase in the antioxidant status, were shown in MLT-treated mice. In conclusion, MLT is a promising candidate that could be considered as a possible functional ingredient capable of preventing cardiovascular risk.

Melatonin in Human Breast Milk and Its Potential Role in Circadian Entrainment: A Nod towards Chrononutrition?

Breastfeeding is the most appropriate source of a newborn’s nutrition; among the plethora of its benefits, its modulation of circadian rhythmicity with melatonin as a potential neuroendocrine transducer has gained increasing interest. Transplacental transfer assures melatonin provision for the fetus, who is devoid of melatonin secretion. Even after birth, the neonatal pineal gland is not able to produce melatonin rhythmically for several months (with an even more prolonged deficiency following preterm birth). In this context, human breast milk constitutes the main natural source of melatonin: diurnal dynamic changes, an acrophase early after midnight, and changes in melatonin concentrations according to gestational age and during the different stages of lactation have been reported. Understudied thus far are the factors impacting on (changes in) melatonin content in human breast milk and their clinical significance in chronobiological adherence in the neonate: maternal as well as environmental aspects have to be investigated in more detail to guide nursing mothers in optimal feeding schedules which probably means a synchronized instead of mistimed feeding practice. This review aims to be thought-provoking regarding the critical role of melatonin in chrononutrition during breastfeeding, highlighting its potential in circadian entrainment and therefore optimizing (neuro)developmental outcomes in the neonatal setting.

Validation of a simple bioanalytical method for the determination of melatonin concentration in human serum using high-performance liquid chromatography with a fluorescent detector

Analysis of melatonin in biological samples is a challenge for the analyst both because of its low concentration and because of the numerous interfering substances. Therefore, chromatography, as a powerful analytical technique used for the separation, detection, and quantification of analytes, can be the method of choice for determining melatonin in biological samples for clinical use and pharmacokinetic research. The method was developed and validated according to the internal documents in accordance with Good Laboratory Practice. The concentrations of melatonin in human serum were determined using a high-performance liquid chromatography method with a fluorescence detector and mirtazapine as an internal standard. Preparation of serum samples was performed by liquid–liquid extraction with ethyl acetate: n-hexane (1:1 v/v). High linearity was exhibited over a concentration range of 25–10,000 pg/mL of melatonin, with a correlation coefficient higher than 0.999 during the course of method validation. Repeatability and intermediate precision show a relative standard deviation lower than 6.6 %, and accuracies were from 90.7 % to 110.3 %. The lower limit of quantitation was 30 pg/mL, and the limit of detection was 7.92 pg/mL. The in-house method is simple, fast, reproducible, and applicable for the determination of melatonin in human serum.

102 Circadian patterns of behavior, respiration, rectal temperature, saliva melatonin, cytokine concentrations, and milk immune cells are altered by cooling heat-stressed lactating sows

Abstract Lactating sows are particularly vulnerable to heat stress (HS) due to the increased metabolism from milk production. A greater understanding of HS response could assist in mitigating its detrimental effects on animal production. Two core circadian clock genes were pinpointed in a recent genome study as potential mediators of HS response, indicating the possible alteration of circadian clocks by HS exposure. This study aimed to assess how cooling of lactating sows under natural heat stress conditions in the summer influenced circadian patterns of respiration rate (RR), rectal temperature (RT), behaviors, salivary concentration of cortisol and melatonin, milk cell populations and relative abundance of multiple cytokines in saliva. Lactating sows of mixed parities were divided into two treatment groups: treated with electronic cooling pad (C; n=9) and heat-stressed control (H; n=9). Experiments were conducted during two 48 h periods of increased environmental temperatures from summer heatwaves. During the initial 48 h period, rectal temperature (RT) was monitored every 60 min, rectal temperature (RT) every 30 min, and behaviors of eating, standing, sitting, laying, sleeping, drinking, and nursing every 5 min. Morning milk samples were collected following the completion of the first phase and utilized to categorize and count somatic cells. The second trial was approximately 1 wk later, and during this period saliva samples were collected every 4 h over the 48-h period. Results were analyzed for significant effect of treatments and interaction using periodic regression while circadian patterns were further detected by incorporating a Fourier series model utilizing sine-cosine variables that denote a fit and/or shift in circadian pattern. The analysis revealed that cooling decreased RT and RR while also modifying circadian patterns (P < 0.05). Cooling had no impact on the percentage of time spent in any activity over the 48-h period (P > 0.05). Nevertheless, the daily patterns of eating, standing, and sitting were different between the treatments (P < 0.05). A shift in eating time to later in the day in H sows relative to C sows related to a second rise in RT during the dark phase of the light-dark cycle (P < 0.05). Saliva melatonin concentrations were increased in C sows and circadian pattern altered relative to H (P < 0.05), but there was no effect on salivary cortisol concentrations (P > 0.05). Cooling reduced milk lymphocytes (P < 0.05) and influenced diurnal pattern of saliva cytokines including interleukins (IL) IL-1 alpha, IL-1 beta, IL-10, and IL-15 and transforming growth factor-beta 1. In conclusion, the cooling of heat-stressed sows altered the circadian patterns of physiology, behavior and melatonin, suggesting the need for additional research to investigate whether circadian disruption contributes to reduced production efficiency observed in HS animals.

Evaluation of Melatonin and Antioxidant Levels in the Serum of Breast Cancer Patients

Metabolites and antioxidants can be altered in patients with various diseases, particularly in those with cancer. This study aims to measure melatonin and total antioxidant levels in the serum of breast cancer patients and compare them with a healthy control group. Both groups had serum samples collected at 2:00 a.m. and 9:00 a.m. Melatonin levels were determined using High-performance liquid chromatography (HPLC), while total antioxidant levels were assessed by Enzyme-linked immunosorbent assay (ELISA). Levels of melatonin and total antioxidants differed between the groups. In the control group, the levels of melatonin and total antioxidants were considerably greater compared to the diagnostic group, with a p-value of 0.001. Melatonin and total antioxidant levels were consistently greater at 2:00 than at 9:00. The maximum melatonin levels recorded in the diagnostic and control groups were 39.3 pg/mL and 65.9 pg/mL, respectively. Melatonin levels varied based on the age of the participants, with higher amounts observed in younger participants compared to older people in both groups. The BMI affected the levels of melatonin, with a greater BMI leading to elevated melatonin concentrations. The diagnostic group had a total antioxidant level of 39.3 pg/mL, while the control group had a level of 65.9 pg/mL. The elevated levels of melatonin and total antioxidants in the control group indicate a healthy status. The research demonstrated a significant correlation between melatonin and antioxidant levels in breast cancer patients, with reduced melatonin levels and total antioxidant levels in the diagnosed group. Elevated BMI was linked to reduced melatonin levels.

Impact of exogenous melatonin foliar application on physiology and fruit quality of wine grapes (Vitis vinifera) under salt stress.

Soil salinisation is an important abiotic stress faced in grape cultivating, leading to weakened plant vigour and reduced fruit quality. Melatonin as a novel hormone has shown positive exogenous application value. Therefore, this study used wine grape (Vitis vinifera ) 'Pinot Noir' as a test material to investigate the changes of foliar spraying with different concentrations of melatonin on the physiology and fruit quality of wine grapes in a field under simulated salt stress (200mmolL-1 NaCl). The results showed that foliar spraying of melatonin significantly increased the intercellular CO2 concentration, maximum photochemical quantum yield of PSII, relative chlorophyll and ascorbic acid content of the leaves, as well as the single spike weight, 100-grain weight, transverse and longitudinal diameters, malic acid, α-amino nitrogen and ammonia content of fruits, and decreased the initial fluorescence value of leaves, ascorbate peroxidase activity, glutathione content, fruit transverse to longitudinal ratio and tartaric acid content of plants under salt stress. Results of the comprehensive evaluation of the affiliation function indicated that 100μmolL-1 melatonin treatment had the best effect on reducing salt stress in grapes. In summary, melatonin application could enhance the salt tolerance of grapes by improving the photosynthetic capacity of grape plants under salt stress and promoting fruit development and quality formation, and these results provide new insights into the involvement of melatonin in the improvement of salt tolerance in crop, as well as some theoretical basis for the development and industrialisation of stress-resistant cultivation techniques for wine grapes.

Novel melatonin-producing Bacillus safensis EH143 mitigates salt and cadmium stress in soybean.

Recently, microorganism and exogenous melatonin application has been recognized as an efficient biological tool for enhancing salt tolerance and heavy metal detoxification in agriculture crops. Thus, the goal of this study was to isolate and evaluate a novel melatonin-producing plant growth promoting bacterium. With high-throughput whole genome sequencing, phytohormone measurements, expression profiling, and biochemical analysis, we can identify a novel PGPB that produces melatonin and unravel how it promotes soybean growth and development and protects against salt and Cd stress. We identify the melatonin synthesis pathway (tryptophan→tryptamine→serotonin melatonin) of the halotolerant (NaCl > 800 mM) and heavy metal-resistant (Cd >3 mM) rhizobacterium Bacillus safensis EH143 and use it to treat soybean plants subjected to Cd and NaCl stresses. Results show that EH143 will highly bioaccumulate heavy metals and significantly improve P and Ca2+ uptake and the K+/Na+ (93%↑under salt stress) ratio while reducing Cd uptake (49% under Cd stress) in shoots. This activity was supported by the expression of the ion regulator HKT1, MYPB67, and the calcium sensors CDPK5 and CaMK1 which ultimately led to increased plant growth. EH143 significantly decreased ABA content in shoots by 13%, 20%, and 34% and increased SA biosynthesis in shoots by 14.8%, 31%, and 48.2% in control, salt, and Cd-treated plants, upregulating CYP707A1 and CYP707A2 and PAL1 and ICS, respectively. The melatonin content significantly decreased along with a reduced expression of ASMT3 following treatment with EH143; moreover, reduced expression of peroxidase (POD) and superoxide dismutase (SOD) by 134.5% and 39% under salt+Cd stress, respectively and increased level of total amino acids were observed. Whole-genome sequencing and annotation of EH143 revealed the presence of the melatonin precursor tryptophan synthase (trpA, trpB, trpS), metal and other ion regulators (Cd: cadA, potassium: KtrA and KtrB, phosphate: glpT, calcium: yloB, the sodium/glucose cotransporter: sgIT, and the magnesium transporter: mgtE), and enzyme activators (including the siderophore transport proteins yfiZ and yfhA, the SOD sodA, the catalase katA1, and the glutathione regulator KefG) that may be involved in programming the plant metabolic system. As a consequence, EH143 treatment significantly reduced the contents of lipid peroxidation (O2-, MDA, and H2O2) up to 69%, 46%, and 29% in plants under salt+Cd stress, respectively. These findings suggest that EH143 could be a potent biofertilizer to alleviate NaCl and Cd toxicity in crops and serve as an alternative substitute for exogenous melatonin application.

Dual-channel sensing strategy for melatonin detection based on iron-cobalt oxide nanosheets with peroxidase-like activity and gold nanoclusters

This work developed a sensitive fluorescence and colorimetric dual-channel sensing system for melatonin determination based on iron-cobalt oxide nanosheets (FeCo-ONSs) and gold nanoclusters (AuNCs). FeCo-ONSs exhibited excellent peroxidase (POD)-like activities, that could catalyze H2O2 to produce reactive oxygen species and further catalyze N-ethyl-N-(3-sulfopropyl)-3-methylaniline sodium (TOPS) to couple with 4-amino-antipyrine (4-AAP) to generate purple compounds (PCs), which had absorption at 549 nm. The generated PCs can quench the fluorescence of AuNCs at 577 nm via fluorescence resonance energy transfer (FRET). The process of the generation of purple compounds would be restrained in existence of melatonin due to its scavenging capacity for free radicals. As a consequence, the absorption at 549 nm decreased, while the fluorescence quenching of AuNCs was weakened, and emission intensity at 577 nm progressively recovered. The recovery of fluorescence and the decrease in absorption depended on the concentration of melatonin. Therefore, by employing fluorescence and colorimetric dual signal monitoring, the linear ranges of melatonin were 5–300 μM and 5–800 μM, and the LODs were 1.17 μM and 2.13 μM, respectively.

Assessment of the dalargin effect on the level of vitamin D and melatonin in blood serum in patients with malignant bone tumors and polymorbidity

Background. Involved in many cascades of biological regulatory reactions, calcium, vitamin D and melatonin create a single metabolic pattern, maintaining the dynamic balance of bone tissue homeostasis. Nevertheless, these regulatory molecules, as structural and functional elements of bone tissue, play a crucial role in various cellular processes associated with oncogenesis and tumor progression. Synthetic peptide dalargin has wound healing, reparative, anti-inflammatory, antioxidant, immunomodulatory, anticarcinogenic, antitumor, and antimetastatic effects. The purpose of the study was to investigate the synthetic neuropeptide dalargin influence on the dynamics of vitamin D and melatonin blood serum le­vels as part of the treatment algorithm of patients with bone malignant tumors of the lower extremities and pelvis with polymorbidity and endoprosthetics. Materials and methods. The study inclu­ded a control (first) group and a main (second) group of clinical observation of patients with malignant bone lesions. The serum melatonin content was measured by enzyme immunoassay using reagent kits (No. RE54021) from IBL-Hamburg GmbH (Germany). Serum levels of 25-hydroxycalciferol (25(OH)D) were determined by the immunochemiluminescent method on an ARCHITECT 25-OH Vitamin D Controls automatic analyzer. Results. In patients who received dalargin, more pronounced positive dynamics were established in the normalization of 25(ОН)D and melatonin levels, and there was no exacerbation of concomitant diseases. In contrast to the data of patients who did not receive dalargin, in the group where it was used, there were no relapses or metastases of the tumor du­ring 14 months. A comparison of the 25(ОН)D and melatonin le­vels in patients 6–7 months and 12–14 months after treatment shows a tendency to recovery of indicators only in patients who were additionally treated with dalargin (p < 0.01). Conclusions. The study showed the possibility of using the neuropeptide dalargin to increase the effectiveness of the treatment of patients with primary malignant tumors with the burden of polymorbidity by influencing the levels of vitamin D and melatonin in the blood serum.

Biosynthetic Pathways of Tryptophan Metabolites in Saccharomyces cerevisiae Strain: Insights and Implications.

Tryptophan metabolites, such as 5-hydroxytryptophan (5-HTP), serotonin, and melatonin, hold significant promise as supplements for managing various mood-related disorders, including depression and insomnia. However, their chemical production via chemical synthesis and phytochemical extraction presents drawbacks, such as the generation of toxic byproducts and low yields. In this study, we explore an alternative approach utilizing S. cerevisiae STG S101 for biosynthesis. Through a series of eleven experiments employing different combinations of tryptophan supplementation, Tween 20, and HEPES buffer, we investigated the production of these indolamines. The tryptophan metabolites were analyzed using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Notably, setups replacing peptone in the YPD media with tryptophan (Run 3) and incorporating tryptophan along with 25 mM HEPES buffer (Run 4) demonstrated successful biosynthesis of 5-HTP and serotonin. The highest 5-HTP and serotonin concentrations were 58.9 ± 16.0 mg L-1 and 0.0650 ± 0.00211 mg L-1, respectively. Melatonin concentrations were undetected in all the setups. These findings underscore the potential of using probiotic yeast strains as a safer and conceivably more cost-effective alternative for indolamine synthesis. The utilization of probiotic strains presents a promising avenue, potentially offering scalability, sustainability, reduced environmental impact, and feasibility for large-scale production.

Melatonin in infants—physiology, pathophysiology and intervention options

AbstractThe effectiveness of melatonin in nonorganic sleep disorders in children and adolescents has been examined in 33 randomised controlled studies [1]. This review presents the current state of knowledge on the physiology, pharmacokinetics, pathophysiology and toxicity of melatonin in infancy based on well-documented studies. Up to the third month of life, premature and full-term babies cannot produce their own melatonin, so they are dependent on exogenous supply via their own mother’s breast milk, non-pooled breast milk or non-pooled formula. Non-pooled means that a distinction should be made between melatonin-rich night milk and melatonin-poor day milk. A number of intervention studies indicate that administration of melatonin to infants may have analgesic and antioxidant effects related to ophthalmological examinations, prevention of bronchopulmonary dysplasia, and the treatment of hypoxic ischaemic encephalopathies. Since melatonin concentrations in the mother’s blood, in breast milk and, e.g., also in cow’s milk show regular day–night fluctuations, and since breastfed infants have a more stable melatonin supply and fewer sleep disorders, infants who cannot be breastfed by their own mother should preferably have chrononutrition made from non-pooled human or cow’s milk. There has recently been evidence that infantile colic is a disorder with delayed development of chronobiological rhythms.

Pre-storage melatonin treatment maintains cell membrane integrity, reduces fruit browning and decay incidence in guava (Psidium guajava)

An experiments were conducted during 2021–22 at ICAR-Indian Agricultural Research Institute, New Delhi to study the impact of melatonin (MT) on key characteristics of guava (Psidium guajava L. cv. Barafkhana). Guava fruits were treated with different MT concentrations (200, 400, 600 and 800 μM) and stored at 10±1°C with 85–90% RH. The research revealed that treating with 600 μM MT notably decreased polyphenoloxidase activity by 57%, leading to delayed peel browning and also suppressed polygalacturonase (PG) activity by approximately 45% and pectine methylesterase activity by about 73%, resulting in higher firmness (5.33 N). Following a 20-days period of cold storage, significant reductions in electrolyte leakage, hydrogen peroxide accumulation and lipoxygenase activity were observed, thereby preserving cell membrane integrity. Additionally, MT stimulated the antioxidant defense system, boosted proline content accumulation, and enhanced phenylalanine ammonia-lyase activity. Together, these effects contributed to enhanced resistance against postharvest fungal decay (8.75%). In conclusion, MT at a concentration of 600 μM proves to be an effective postharvest treatment for maintaining texture, reducing fruit decay and extending the shelf-life of guava during cold storage.

Ovarian overexpression of ASMT gene increases follicle numbers in transgenic sheep: Association with lipid metabolism

Melatonin plays an important role in mammalian reproductive activities, to further understand the effects of endogenous melatonin on functions of ovary, the transgenic sheep with overexpression of melatonin synthetic enzyme gene ASMT in ovary were generated. The results showed that total melatonin content in follicular fluid of transgenic sheep was significantly greater than that in the wild type. Accordingly, the follicle numbers of transgenic sheep were also significantly greater than those in the WT. The results of follicular fluid metabolites sequencing showed that compared with WT, the differential metabolites of the transgenic sheep were significantly enriched in several signaling pathways, the largest number of metabolites was lipid metabolism pathway and the main differential metabolites were lipids and lipoid molecules. SMART-seq2 were used to analyze the oocytes and granulosa cells of transgenic sheep and WT sheep. The main differential enrichment pathway was metabolic pathway, in which lipid metabolism genes accounted for the majority. In conclusion, this is the first report to show that ovary overexpression of ASMT increased local melatonin production and follicle numbers. These results may imply that ASMT plays an important role in follicle development and formation, and melatonin intervention may be a potential method to promote this process.

Changes in Behavior and Diel Melatonin Secretion Toward Estivation in Western Sand Lance, Ammodytes japonicus (Uranoscopiformes, Ammodytidae).

Western sand lance, Ammodytes japonicus, is known to have an estivation period, in which they cease feeding and stay in the sand from early summer to late autumn, followed by gonadal maturation. During the feeding period prior to estivation, they swim in daytime and spend the night in the sand. Before they start swimming, they show a typical behavior of head-exposing from the sand, which is likely to be related to foraging and predation avoidance. Our previous study revealed that melatonin regulates such diel behavior of this species. To elucidate the mechanisms of behavioral regulation throughout the life cycle of this sand lance, the present study examined the changes in behavior and melatonin secretion toward the estivation period. Both head-exposing and swimming behaviors were frequently observed at the transition period toward estivation. On the other hand, occurrence of these behaviors was suppressed just before entering estivation. Subsequently, it was found that plasma melatonin concentration was about three times higher at night than in daytime in the non-estivation period, while it was retained at high levels throughout the day in the estivation period. These results indicate that diurnal swimming behavior of sand lance from the feeding to estivation periods is associated with the daily cycle of melatonin secretion.

Alteration of circadian sleep-wake rhythm and salivary melatonin secretion in idiopathic/isolated REM sleep behavior disorder: Preliminary evidence

Objective/BackgroundIdiopathic/isolated REM sleep behavior disorder (iRBD) is widely regarded as an early sign of neurodegeneration leading to synucleinopathies. While circadian rhythm alterations in iRBD have been preliminarily demonstrated, evidence on melatonin secretion patterns in this clinical condition is limited. To address this knowledge gap, this exploratory study aimed to integrate salivary melatonin measurement with actigraphic monitoring in individuals with iRBD and age-matched healthy controls (HC) under real-life conditions. MethodsParticipants diagnosed with iRBD and HC underwent clinical evaluation and wore an actigraph for seven days and nights. Salivary melatonin concentrations were measured at five time points during the last night of recording. Comparative analyses were conducted on clinical data, actigraphic parameters, and melatonin levels between the two groups. ResultsiRBD participants (n = 18) showed greater motor (p < 0.01) and non-motor symptoms (p < 0.001), alongside disruptions in circadian sleep-wake rhythm compared to HC (n = 10). Specifically, actigraphy revealed a delayed central phase measurement (p < 0.05), reduced activity during the most active hours (p < 0.001), and decreased relative amplitude (p < 0.05). Total salivary melatonin concentration was significantly lower in iRBD (p < 0.05), with a slight but non-significant phase delay in dim light melatonin onset. ConclusionsThis exploratory study highlights a dysregulation of circadian sleep-wake rhythm coupled with reduced melatonin secretion in iRBD. Future research could add to these preliminary findings to evaluate novel treatment approaches to regulate the sleep-wake cycle and elucidate the implications of circadian dysregulation in the conversion from iRBD to neurodegeneration.

Effects of Light Spectrum on Survival, Growth, Physiological, and Biochemical Indices of Redclaw Crayfish (Cherax quadricarinatus) Juveniles

The spectrum is a key environmental factor, and light-emitting diodes (LEDs) can influence the growth and development of crustaceans by altering the composition of the spectrum. This study conducted a 30-day experiment to investigate the effects of five LED spectra (red, yellow, blue, green, and white light) on the growth, antioxidant and immune enzyme activities, stress hormone levels, and the expression of α-amylase (α-AMY), ecdysone receptor (EcR) and retinoid X receptor (RXR) genes in juvenile redclaw crayfish (Cherax quadricarinatus). The results show that the survival rate of juveniles is markedly higher in the yellow and red-light groups than in the other three groups (P&lt;0.05). The green light group exhibits the lowest survival rate, yet it demonstrates the highest weight gain rate and specific growth rate. Regarding enzyme activity and hormone levels, the yellow light group shows the lowest malondialdehyde content, with higher superoxide dismutase and acid phosphatase activity than the other groups; no significant differences are observed in lysozyme activity among the groups (P&gt;0.05). The melatonin content in the green and blue light groups is significantly higher than that in the other three groups (P&lt;0.01). In terms of growth gene expression, the expression of α-AMY, EcR, and RXR in juvenile C. quadricarinatus is regulated by the spectrum. In conclusion, when raised under the yellow light spectrum, juvenile C. quadricarinatus displays elevated survival rates, rapid growth, and robust antioxidant and immune defenses. This study provides important technical parameters for optimizing and enhancing the industrial cultivation of juvenile C. quadricarinatus.

Influence of Melatonin Coating on Physiochemical Qualities and Enzymatic Activities in Banana Pericarp under Cold Storage

Banana pericarp is highly susceptible to chilling injury (CI), negatively affecting its quality and shelf life. Melatonin (MT), a plant tryptophan derivative, has shown promising effects in mitigating CI and related physiological disorders in tropical and subtropical fruits. This study investigated the efficacy of MT at different concentrations (0, 50, and 100 µM/L) in the coating of banana pericarp to control CI and physicochemical degradation during storage at 7 °C for five days, and on each day, fruits were assessed for quality. The MT100 treatment significantly (p &lt; 0.05) mitigated the severity of the CI index, electrolytic leakage (EL), and malondialdehyde (MDA) levels. Reactive oxygen species (ROS) levels were substantially higher in control samples, whereas MT treatments notably suppressed their increase. Glutathione (GSH) and ascorbic acid (AA) levels were elevated in those banana pericarps treated with higher MT concentrations. Although total phenolic content (TPC) and total carotenoid contents (TCC) were increased in MT-treated samples, the MT concentrations did not significantly affect them. The level of phenolic compounds, such as gallic acid (GA), chlorogenic acid (CA), quinic acid (QA), protocatechuic acid (PA), and catechin (CC), exhibited continuous growth during the storage period, with the highest levels found in MT100-treated samples. Activities of enzymes such as lipoxygenase (LOX), phospholipase D (PLD), phenylalanine ammonia-lyase (PAL), and polyphenol oxidase (PPO) were significantly (p &lt; 0.05) higher in control samples and rose continuously over time, yet were effectively reduced in MT-treated pericarps. This study shows that applying a higher MT coating (100 µM/L) to bananas is an effective post-harvest strategy to considerably lower the incidence of CI and associated losses.

Development of an Antioxidant-Rich Sugar-Free Plantain Candy and Assessment of Its Shelf Life in a Flexible Laminate.

Candy is a popular confection worldwide, and it would be beneficial to society if it were converted into a source of antioxidant molecules to eliminate its adverse health effects. The amount of antioxidants available even in fruit candies is questionable due to the high thermal processing losses they undergo and the presence of various food additives. Plantains (Musa paradisiaca) are less known as good sources of biotherapeutic antioxidants, namely l-tryptophan, serotonin and melatonin, and consumption of this highly nutritious fruit is limited to underdeveloped and developing countries. The objectives of this study are: to develop a functional antioxidant-rich sugar-free plantain-based candy with valuable contents of the mentioned biomolecules in synergy; and to ensure its extended shelf life without compromising its physicochemical properties and functionality by wrapping it with a suitable packaging laminate. To accomplish the first objective, lyophilized plantain powder, sorbitol and mannitol were used as base materials with minimal additives under minimal processing conditions to reduce processing loss. Sensory, proximate, physicochemical and phytochemical properties, including the antioxidant synergy among the mentioned biomolecules of the developed candies were evaluated. For the second objective, the candies were enclosed in two different flexible packaging laminates and the optimal packaging was determined based on the microbiological safety and sensory appeal of the wrapped candies. Subsequently, the above-mentioned properties of the packaged (in the most suitable laminate) candies were evaluated at regular time intervals during storage for assessment of their shelf life. The candy had a characteristic flavour of plantain, uniform dark brown colour, rich mouthfeel, pleasant aroma, moderately hard texture and moderate sweetness, along with high antioxidant activity and considerable content of l-tryptophan, serotonin and melatonin (present as a synergistic consortium). During storage of the packaged candy under ambient conditions, it remained microbiologically safe for up to 56 days, and also maintained sensory attributes, antioxidant activity and synergy compared to the control candy. This newly developed semi-hard sugar-free candy with high antioxidant content, containing three important antioxidants, namely l-tryptophan, serotonin and melatonin, could be a good source of biotherapeutic molecules and a substitute for commercial candies consumed globally.