Background/Objectives: Melatonin is widely used as a sleep aid and is generally considered safe; moreover, it is well known for its cardioprotective properties. Nonetheless, little is known about the underlying mechanisms of melatonin. Indeed, some potential undesirable cardiovascular effects associated with melatonin supplementation have been observed. Methods: We conducted a systematic review to evaluate evidence relevant to a case involving a 63-year-old man who developed ventricular arrhythmia while taking 10 mg of exogenous melatonin daily, exhibiting cardiovascular symptoms, and was then diagnosed with ventricular arrhythmia. After discontinuing melatonin, the patient fully recovered from all cardiovascular symptoms. Results: Following withdrawal of melatonin, the patient experienced complete resolution of symptoms and improvement in electrocardiographic findings. The systematic review identified reports describing similar arrhythmic events associated with melatonin supplementation, with symptom resolution or clinical improvement after discontinuation of the supplement. Conclusions: Although melatonin is generally regarded as safe, with cardioprotective effects, in this review we discuss possible mechanisms involving melatonin receptors, sleep architecture, pharmacokinetic variability, and genetic predisposition which could be associated with cardiac rhythm and conduction disturbances. Herein, we highlight the necessity for further studies to identify risk factors and underlying mechanisms and guide the safe use of this molecule.

Alkylating agents, historically employed as chemical warfare agents and currently used as chemotherapeutic drugs, are known to induce significant pulmonary toxicity. Current clinical interventions often fail to fully prevent or reverse these pathological changes, highlighting the urgent need for safe, broad-spectrum therapeutic agents that are effective across diverse exposure scenarios. Melatonin has emerged as a promising protective agent due to its antioxidant, anti-inflammatory, and immunomodulatory properties, along with a well-established safety profile. This systematic review evaluates the potential of melatonin in mitigating vesicant-induced pulmonary damage, synthesizing and critically analyzing preclinical evidence in accordance with the PRISMA guidelines. Three in vivo rodent studies met the inclusion criteria and were analyzed. In all cases, melatonin demonstrated protective effects against alkylating agents such as mechlorethamine (HN2) and cyclophosphamide (CP). These effects were dose-dependent and observed across various animal models, administration protocols, and dosages (ranging from 2.5 to 100 mg/kg), highlighting the importance of context-specific considerations. The human equivalent doses (HEDs) ranged from 12 to 973 mg per day, suggesting that the effective doses may exceed those typically used in clinical trials for other conditions. Melatonin’s pleiotropic mechanisms, including a reduction in oxidative stress, the modulation of inflammatory pathways, and support for tissue repair, reinforce its therapeutic potential in both prophylactic and treatment settings for alkylating agent exposure. Nonetheless, this review underscores the critical need for further randomized clinical trials to establish the optimal dosing strategies, refine treatment protocols, and fully elucidate melatonin’s role in managing alkylating-agent-induced pulmonary toxicity.

BACKGROUND AND PURPOSE:Traumatic brain injury (TBI) is considered to be a leading cause of mortality and disability worldwide. After TBI, innate immunity is rapidly activated in response to damage-associated molecular patterns, such as ATP release, recognised by P2X7 receptors. The P2X7-NLRP3 inflammasome axis has been identified as one of the main players in neuroinflammation. This study aimed to validate P2X7 receptors as therapeutic target for traumatic brain injury. EXPERIMENTAL APPROACH:P2X7 receptors were studied by genetic and pharmacological approaches. Six non-nucleotide purine derivatives were evaluated as P2X7 antagonists. Compounds that prevented LPS + ATP-induced IL-1β release from primary glial cultures were investigated in the closed-head injury TBI model in vivo in male mice. Finally, we evaluated soluble (s)P2X7 receptor plasmatic levels in a cohort of TBI patients. KEY RESULTS:P2rx7-/- mice showed an exaggerated inflammatory response 24 h post-TBI compared to control mice. However, animals treated with the selective P2X7 antagonist JNJ-47965567 (30 mg kg-1 i.p.) 30 min post-TBI showed improved neurological and inflammatory parameters. The purine derivative ITH15004 was the most potent compound reducing IL-1β production in vitro. When administered in vivo 30 min post-TBI, ITH15004 (1 mg kg-1 i.p.) improved both neuro-behavioural and inflammatory markers at 24 h. In TBI patients, we showed a tendency towards increase in circulating sP2X7 receptor levels at 24 and 72 h post-TBI. CONCLUSIONS AND IMPLICATIONS:These results highlight the importance of P2X7 receptors in the acute phase of TBI and present ITH15004 as a promising pharmacological tool to counteract P2X7 receptor-dependent neuroinflammation in vivo.

Triazole pesticides are widely used throughout the world, but their abuse causes toxic effects in non-targeted organisms. In the present study, the cytotoxic effect of the triazole ipconazole was evaluated in porcine and ram spermatozoa. Ipconazole significantly reduced sperm viability, increased ROS levels, altered catalase and SOD enzyme activity, and caused alterations in the molecular mRNA expression of structural biomarkers (PRM1, ODF2, AKAP4, THEG, SPACA3 and CLGN) related to fertility in males, as well as the overexpression of BAX (cell death) and ROMO1 (oxidative stress) mRNA. Our results indicate that the fungicide triazole is involved in cellular, enzymatic and molecular alteration of porcine and ram spermatozoa, and is possibly a factor in the development of infertility in male mammals.

1 Universidad Complutense de Madrid (SPAIN)2 Universidad Rey Juan Carlos (SPAIN)3 Universidad Autónoma de Madrid (SPAIN)

Sulfur and nitrogen mustards, bis(2-chloroethyl)sulfide and tertiary bis(2-chloroethyl) amines, respectively, are vesicant warfare agents with alkylating activity. Moreover, oxidative/nitrosative stress, inflammatory response induction, metalloproteinases activation, DNA damage or calcium disruption are some of the toxicological mechanisms of sulfur and nitrogen mustard-induced injury that affects the cell integrity and function. In this review, we not only propose melatonin as a therapeutic option in order to counteract and modulate several pathways involved in physiopathological mechanisms activated after exposure to mustards, but also for the first time, we predict whether metabolites of melatonin, cyclic-3-hydroxymelatonin, N1-acetyl-N2-formyl-5-methoxykynuramine, and N1-acetyl-5-methoxykynuramine could be capable of exerting a scavenger action and neutralize the toxic damage induced by these blister agents. NLRP3 inflammasome is activated in response to a wide variety of infectious stimuli or cellular stressors, however, although the precise mechanisms leading to activation are not known, mustards are postulated as activators. In this regard, melatonin, through its anti-inflammatory action and NLRP3 inflammasome modulation could exert a protective effect in the pathophysiology and management of sulfur and nitrogen mustard-induced injury. The ability of melatonin to attenuate sulfur and nitrogen mustard-induced toxicity and its high safety profile make melatonin a suitable molecule to be a part of medical countermeasures against blister agents poisoning in the near future.

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.

It is now an accepted principle that epigenetic alterations cause cellular dyshomeostasis and functional changes, both of which are essential for the initiation and completion of the tumor cycle. Oral carcinogenesis is no exception in this regard, as most of the tumors in the different subsites of the oral cavity arise from the cross-reaction between (epi)genetic inheritance and the huge challenge of environmental stressors. Currently, the biochemical machinery is put at the service of the tumor program, halting the cell cycle, triggering uncontrolled proliferation, driving angiogenesis and resistance to apoptosis, until the archetypes of the tumor phenotype are reached. Melatonin has the ability to dynamically affect the epigenetic code. It has become accepted that melatonin can reverse (epi)genetic aberrations present in oral and other cancers, suggesting the possibility of enhancing the oncostatic capacity of standard multimodal treatments by incorporating this indolamine as an adjuvant. First steps in this direction confirm the potential of melatonin as a countermeasure to mitigate the detrimental side effects of conventional first-line radiochemotherapy. This single effect could produce synergies of extraordinary clinical importance, allowing doses to be increased and treatments not to be interrupted, ultimately improving patients' quality of life and prognosis. Motivated by the urgency of improving the medical management of oral cancer, many authors advocate moving from in vitro and preclinical research, where the bulk of melatonin cancer research is concentrated, to systematic randomized clinical trials on large cohorts. Recognizing the challenge to improve the clinical management of cancer, our motivation is to encourage comprehensive and robust research to reveal the clinical potential of melatonin in oral cancer control. To improve the outcome and quality of life of patients with oral cancer, here we provide the latest evidence of the oncolytic activity that melatonin can achieve by manipulating epigenetic patterns in oronasopharyngeal tissue.

The role of inflammation and immunity in the pathomechanism of neurodegenerative diseases has become increasingly relevant within the past few years. In this context, the NOD-like receptor protein 3 (NLRP3) inflammasome plays a crucial role in the activation of inflammatory responses by promoting the maturation and secretion of pro-inflammatory cytokines such as interleukin-1β and interleukin-18. We hypothesized that the interplay between nuclear factor erythroid 2-related factor 2 (Nrf2) and NADPH oxidase 4 (NOX4) may play a critical role in the activation of the NLRP3 inflammasome and subsequent inflammatory responses. After priming mixed glial cultures with lipopolysaccharide (LPS), cells were stimulated with ATP, showing a significant reduction of IL1-β release in NOX4 and Nrf2 KO mice. Importantly, NOX4 inhibition using GKT136901 also reduced IL-1β release, as in NOX4 KO mixed glial cultures. Moreover, we measured NOX4 and NLRP3 expression in wild-type mixed glial cultures following LPS treatment, observing that both increased after TLR4 activation, while 24 h treatment with tert-butylhydroquinone, a potent Nrf2 inducer, significantly reduced NLRP3 expression. LPS administration resulted in significant cognitive impairment compared to the control group. Indeed, LPS also modified the expression of NLRP3 and NOX4 in mouse hippocampus. However, mice treated with GKT136901 after LPS impairment showed a significantly improved discrimination index and recovered the expression of inflammatory genes to normal levels compared with wild-type animals. Hence, we here validate NOX4 as a key player in NLRP3 inflammasome activation, suggesting NOX4 pharmacological inhibition as a potent therapeutic approach in neurodegenerative diseases.

The aim of this review is to explore the relationship between melatonin, free radicals, and non-excitatory amino acids, and their role in stroke and aging. Melatonin has garnered significant attention in recent years due to its diverse physiological functions and potential therapeutic benefits by reducing oxidative stress, inflammation, and apoptosis. Melatonin has been found to mitigate ischemic brain damage caused by stroke. By scavenging free radicals and reducing oxidative damage, melatonin may help slow down the aging process and protect against age-related cognitive decline. Additionally, non-excitatory amino acids have been shown to possess neuroprotective properties, including antioxidant and anti-inflammatory in stroke and aging-related conditions. They can attenuate oxidative stress, modulate calcium homeostasis, and inhibit apoptosis, thereby safeguarding neurons against damage induced by stroke and aging processes. The intracellular accumulation of certain non-excitatory amino acids could promote harmful effects during hypoxia-ischemia episodes and thus, the blockade of the amino acid transporters involved in the process could be an alternative therapeutic strategy to reduce ischemic damage. On the other hand, the accumulation of free radicals, specifically mitochondrial reactive oxygen and nitrogen species, accelerates cellular senescence and contributes to age-related decline. Recent research suggests a complex interplay between melatonin, free radicals, and non-excitatory amino acids in stroke and aging. The neuroprotective actions of melatonin and non-excitatory amino acids converge on multiple pathways, including the regulation of calcium homeostasis, modulation of apoptosis, and reduction of inflammation. These mechanisms collectively contribute to the preservation of neuronal integrity and functions, making them promising targets for therapeutic interventions in stroke and age-related disorders.

Protein phosphatase 2A (PP2A) is an important Ser/Thr phosphatase that participates in the regulation of multiple cellular processes. This implies that any deficient activity of PP2A is the responsible of severe pathologies. For instance, one of the main histopathological features of Alzheimer's disease is neurofibrillary tangles, which are mainly comprised by hyperphosphorylated forms of tau protein. This altered rate of tau phosphorylation has been correlated with PP2A depression AD patients. With the goal of preventing PP2A inactivation in neurodegeneration scenarios, we have aimed to design, synthesize and evaluate new ligands of PP2A capable of preventing its inhibition. To achieve this goal, the new PP2A ligands present structural similarities with the central fragment C19-C27 of the well-established PP2A inhibitor okadaic acid (OA). Indeed, this central moiety of OA does not exert inhibitory actions. Hence, these compounds lack PP2A-inhibiting structural motifs but, in contrast, compete with PP2A inhibitors, thus recovering phosphatase activity. Proving this hypothesis, most compounds showed a good neuroprotective profile in neurodegeneration models related to PP2A impairment, highlighting derivative 10, named ITH12711, as the most promising one. This compound (1) restored in vitro and cellular PP2A catalytic activity, measured on a phospho-peptide substrate and by western-blot analyses, (2) proved good brain penetration measured by PAMPA, and (3) prevented LPS-induced memory impairment of mice in the object recognition test. Thus, the promising outcomes of the compound 10 validate our rational approach to design new PP2A-activating drugs based on OA central fragment.

Neurodegeneration affects a large number of cell types including neurons,astrocytes or oligodendrocytes,and neural stem cells.Neural stem cells can generate new neuronal populations through proliferation,migration,and differentiation.This neurogenic potential may be a relevant factor to fight neurodegeneration and aging.In the last years,we can find growing evidence suggesting that melatonin may be a potential modulator of adult hippocampal neurogenesis.The lack of therapeutic strategies targeting neurogenesis led researchers to explore new molecules.Numerous preclinical studies with melatonin observed how melatonin can modulate and enhance molecular and signaling pathways involved in neurogenesis.We made a special focus on the connection between these modulation mechanisms and their implication in neurodegeneration,to summarize the current knowledge and highlight the therapeutic potential of melatonin.

In higher education is frequent that final assessment is the only method of evaluation of students. This traditional method is gradually being replaced by continuous evaluation in the last years, more professors are now implementing new methods, not only of teaching but also of evaluation. New technologies facilitate these new methods in higher education, the Office for Technology developed a Virtual Campus where innovative tools and resources are available both for teachers and students. In this web-based tool, we can develop innovative and creative virtual tools as well as many kinds of resources to improve current teaching and evaluation methods. Therefore, our teaching team decided to develop a continuous assessment method for Toxicology students. The teacher's team collected several scoring activities to develop the continuous assessment procedures [1]. Then our working group scheduled several meetings to decide which new tools of assessment will be implemented: Written individual assignments, language individual written exercises, virtual tests, informative videos exercises, and virtual laboratories.Throughout the classes, we observed that the motivation and participation of students were increased with respect to other courses in which these tasks and assessments were not proposed. This motivation will probably be an important factor in the improvement of the obtained grades.References:[1] R. Hernandez. Does continuous assessment in higher education support student learning? (2012). High Educ 64:489–502. DOI 10.1007/s10734-012-9506-7

NLRP3 is involved in the pathophysiology of several inflammatory diseases. Therefore, there is high current interest in the clinical development of new NLRP3 inflammasome small inhibitors to treat these diseases. Novel N-sulfonylureas were obtained by the replacement of the hexahydroindacene moiety of the previously described NLRP3 inhibitor MCC950. These new derivatives show moderate to high potency in inhibiting IL-1β release in vitro. The greatest effect was observed for compound 4b, which was similar to MCC950. Moreover, compound 4b was able to reduce caspase-1 activation, oligomerization of ASC, and therefore, IL-1β processing. Additional in silico predictions confirmed the safety profile of compound 4b, and in vitro studies in AML12 hepatic cells confirmed the absence of toxicological effects. Finally, we evaluated in vivo anti-inflammatory properties of compound 4b, which showed a significant anti-inflammatory effect and reduced mechanical hyperalgesia at 3 and 10 mg/kg (i.p.) in an in vivo mouse model of gout.

During the transition from the pandemic sanitary alert caused by the Coronavirus disease (COVID-19) to reaching normality in teaching, some Universities opted to continue with blended teaching. Particularly in cases when the number of students, to comply with the safety distance specified by the Government, make impossible to teach all the laboratories in in-person sessions.Therefore, we decided to develop blended laboratory practices in Toxicology. Last academic course we need to develop a complete virtual toxicology laboratory [1], therefore, we decided to design a blended version where students can develop practices in the laboratory in smaller groups to comply with safety distance and complete the rest of the practical experience in the virtual toxicology laboratory. After the practices, to evaluate the experience from the student's point of view we design a survey [2]. This survey was divided into three blocks. The first block included questions about previous knowledge. The second part involved questions about the virtual experience, and in the last block, they write about the advantages and inconveniences of the experience and method comparison. The obtained results were quite satisfying, most of the students refer that they improved their knowledge, with a satisfactory effort dedicated. More than half of the students admit their previous technical skills were improvable. When comparing this blended teaching method to classical lectures in the laboratory, they believe that a complete in-person laboratory with virtual tools available would result in a better experience. Conversely, more than half of the surveys revealed that students will increase their interest if the blended methodology is applied.We conclude that blended teaching can be useful to complete classical learning methods, but students prefer traditional practices in the laboratory if they have to choose between both methods.References:[1] A. ROMERO; C. GARCÍA-CANTÓN; E. RAMOS. A virtual-learning toxicology experience. 15th International Technology, Education and Development Conference (INTED). Valencia (Spain), March 2-4th 2021(Carácter internacional) ISBN: 978-84-09-17939-8[2] L. Graso, Encuestas. Elementos para su diseño y análisis. Córdoba/Argentina: Encuentro Grupo Editor, 2006.

N-Propargylamines are useful synthetic scaffolds for the synthesis of bioactive molecules, and in addition, they possess important pharmacological activities. We obtained several neuroprotective molecules, chiral 1,2-amino alcohols and 1,2-diamines, able to reduce by almost 70% the rotenone and oligomycin A-induced damage in SH-SY5Y cells. Furthermore, some molecules assessed also counteracted the toxicity evoked by the Ser/Thr phosphatase inhibitor okadaic acid. Before extrapolating these data to preclinical studies, we analyze the molecules through an in silico prediction system to detect carcinogenicity risk or other toxic effects. In light of these promising results, these molecules may be considered as a lead family of neuroprotective and relatively safe compounds.

Viral infections constitute a tectonic convulsion in the normophysiology of the hosts. The current coronavirus disease 2019 (COVID-19) pandemic is not an exception, and therefore the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, like any other invading microbe, enacts a generalized immune response once the virus contacts the body. Melatonin is a systemic dealer that does not overlook any homeostasis disturbance, which consequently brings into play its cooperative triad, antioxidant, anti-inflammatory, and immune-stimulant backbone, to stop the infective cycle of SARS-CoV-2 or any other endogenous or exogenous threat. In COVID-19, the corporal propagation of SARS-CoV-2 involves an exacerbated oxidative activity and therefore the overproduction of great amounts of reactive oxygen and nitrogen species (RONS). The endorsement of melatonin as a possible protective agent against the current pandemic is indirectly supported by its widely demonstrated beneficial role in preclinical and clinical studies of other respiratory diseases. In addition, focusing the therapeutic action on strengthening the host protection responses in critical phases of the infective cycle makes it likely that multi-tasking melatonin will provide multi-protection, maintaining its efficacy against the virus variants that are already emerging and will emerge as long as SARS-CoV-2 continues to circulate among us.