Divergent Importance of Chronobiological Considerations in High- and Low-dose Melatonin Therapies

The melatonin contained in beer can provide health benefits, due to its antioxidant, anti-inflammatory and immunomodulatory properties

Beer is a fermented beverage with a low alcohol content originating from cereal fermentation (barley or wheat). It forms part of the diet for many people. It contains melatonin (N-acetyl-5-methoxytryptamine). Melatonin is a molecule with a wide range of antioxidant, oncostatic, immunomodulatory, and cytoprotective properties. The aim of this work was to review the data supporting the idea that a moderate consumption of beer, because of its melatonin content, is particularly useful in healthy diets and in other physiological situations (such as pregnancy, menopause, and old age). Data source: a) The MEDLINE /PubMed search was conducted from 1975 to April 2022, and b) Our own experience and published studies on melatonin, the immune system, and beer. We provide a review of research on the mechanisms of melatonin generation in beer, its concentrations, and its possible effects on health. The melatonin contained in beer, as part of a healthy diet and in some special physiological situations, could act as a protective factor and improve the quality of life of those who drink it in moderation. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Therapeutic Potential of Melatonin Counteracting Chemotherapy-Induced Toxicity in Breast Cancer Patients: A Systematic Review

The purpose of this systematic review is to provide an overview of the existing knowledge on the therapeutic potential of melatonin to counteract the undesirable effects of chemotherapy in breast cancer patients. To this aim, we summarized and critically reviewed preclinical- and clinical-related evidence according to the PRISMA guidelines. Additionally, we developed an extrapolation of melatonin doses in animal studies to the human equivalent doses (HEDs) for randomized clinical trials (RCTs) with breast cancer patients. For the revision, 341 primary records were screened, which were reduced to 8 selected RCTs that met the inclusion criteria. We assembled the evidence drawn from these studies by analyzing the remaining gaps and treatment efficacy and suggested future translational research and clinical trials. Overall, the selected RCTs allow us to conclude that melatonin combined with standard chemotherapy lines would derive, at least, a better quality of life for breast cancer patients. Moreover, regular doses of 20 mg/day seemed to increase partial response and 1-year survival rates. Accordingly, this systematic review leads us to draw attention to the need for more RCTs to provide a comprehensive view of the promising actions of melatonin in breast cancer and, given the safety profile of this molecule, adequate translational doses should be established in further RCTs.

Special Issue on “Pleiotropic Benefits of Melatonin: From Basic Mechanisms to Disease”

Melatonin (N-acetyl-5-methoxytryptamine) is a multifunctional hormone that is naturally produced from tryptophan and released rhythmically throughout the night by the pineal gland to regulate sleep–wake cycles [...]

Melatonin Prescription in Children and Adolescents in Relation to Body Weight and Age

The prescription of melatonin to children and adolescents has increased dramatically in Sweden and internationally during the last ten years. In the present study we aimed to evaluate the prescribed melatonin dose in relation to body weight and age in children. The population-based BMI Epidemiology Study Gothenburg cohort has weight available from school health care records, and information on melatonin prescription through linkage with high-quality national registers. We included prescriptions of melatonin to individuals below 18 years of age where a weight measurement not earlier than three months before, or later than six months after the dispensing date, was available (n = 1554). Similar maximum doses were prescribed to individuals with overweight orobesity as to individuals with normal weight, and to individuals below and above 9 years of age. Age and weight only explained a marginal part of the variance in maximum dose, but were inversely associated and explained a substantial part of the variance in maximum dose per kg. As a result, individuals overweight or with obesity, or age above 9 years, received lower maximum dose per kg of body weight, compared with individuals with normal weight or below 9 years of age. Thus, the prescribed melatonin dose to individuals under 18 years of age is not primarily informed by body weight or age, resulting in substantial differences in prescribed dose per kg of body weight across BMI and age distribution.

Melatonin inhibits Gram-negative pathogens by targeting citrate synthase

Bacterial infections caused by Gram-negative pathogens represent a growing burden for public health worldwide. Despite the urgent need for new antibiotics that effectively fight against pathogenic bacteria, very few compounds are currently under development or approved in the clinical setting. Repurposing compounds for other uses offers a productive strategy for the development of new antibiotics. Here we report that the multifaceted melatonin effectively improves survival rates of mice and decreases bacterial loads in the lung during infection. Mechanistically, melatonin specifically inhibits the activity of citrate synthase of Gram-negative pathogens through directly binding to the R300, D363, and H265 sites, particularly for the notorious Pasteurella multocida. These findings highlight that usage of melatonin is a feasible and alternative therapy to tackle the increasing threat of Gram-negative pathogen infections via disrupting metabolic flux of bacteria.

Melatonin and Pathological Cell Interactions: Mitochondrial Glucose Processing in Cancer Cells

Melatonin is synthesized in the pineal gland at night. Since melatonin is produced in the mitochondria of all other cells in a non-circadian manner, the amount synthesized by the pineal gland is less than 5% of the total. Melatonin produced in mitochondria influences glucose metabolism in all cells. Many pathological cells adopt aerobic glycolysis (Warburg effect) in which pyruvate is excluded from the mitochondria and remains in the cytosol where it is metabolized to lactate. The entrance of pyruvate into the mitochondria of healthy cells allows it to be irreversibly decarboxylated by pyruvate dehydrogenase (PDH) to acetyl coenzyme A (acetyl-CoA). The exclusion of pyruvate from the mitochondria in pathological cells prevents the generation of acetyl-CoA from pyruvate. This is relevant to mitochondrial melatonin production, as acetyl-CoA is a required co-substrate/co-factor for melatonin synthesis. When PDH is inhibited during aerobic glycolysis or during intracellular hypoxia, the deficiency of acetyl-CoA likely prevents mitochondrial melatonin synthesis. When cells experiencing aerobic glycolysis or hypoxia with a diminished level of acetyl-CoA are supplemented with melatonin or receive it from another endogenous source (pineal-derived), pathological cells convert to a more normal phenotype and support the transport of pyruvate into the mitochondria, thereby re-establishing a healthier mitochondrial metabolic physiology.

Impact of Pharmacotherapy on Insomnia in Patients with Alzheimer's Disease

Insomnia is a pervasive sleep disorder affecting numerous patients across diverse demographical populations and comorbid disease states. Contributing factors are often a complex interaction of biological, psychological, and social components, requiring a multifaceted approach in terms of both diagnosis and management. In the setting of Alzheimer’s disease, insomnia is an even more complicated issue, with a higher overall prevalence than in the general population, greater complexity of contributing etiologies, and differences in diagnosis (at times based on caregiver observation of sleep disruption rather than subjective complaints by the individual with the disorder), and requiring more discretion in terms of treatment, particularly in regard to adverse effect profile concerns. There also is growing evidence of the bidirectional nature of sleep disruption and Alzheimer’s disease, with insomnia potentially contributing to disease progression, making the condition even more paramount to address. The objective of this review was to provide the clinician with an overview of treatment strategies that may have value in the treatment of disturbed sleep in Alzheimer’s disease. Nonpharmacological approaches to treatment should be exhausted foremost; however, pharmacotherapy may be needed in certain clinical scenarios, which can be a challenge for clinicians given the paucity of evidence and guidelines for treatment in the subpopulation of Alzheimer’s disease. Agents such as sedating antidepressants, melatonin, and site-specific γ-aminobutyric acid agonists are often employed based on historical usage but are not necessarily supported by high-quality trials. Newer agents such as dual orexin receptor antagonists have demonstrated some promise but still need further evaluation.

Melatonin, Its Metabolites and Their Interference with Reactive Nitrogen Compounds

Melatonin and several of its metabolites are interfering with reactive nitrogen. With the notion of prevailing melatonin formation in tissues that exceeds by far the quantities in blood, metabolites come into focus that are poorly found in the circulation. Apart from their antioxidant actions, both melatonin and N¹-acetyl-5-methoxykynuramine (AMK) downregulate inducible and inhibit neuronal NO synthases, and additionally scavenge NO. However, the NO adduct of melatonin redonates NO, whereas AMK forms with NO a stable product. Many other melatonin metabolites formed in oxidative processes also contain nitrosylatable sites. Moreover, AMK readily scavenges products of the CO₂-adduct of peroxynitrite such as carbonate radicals and NO₂. Protein AMKylation seems to be involved in protective actions.