ROS-induced oxidative damage in lymphocytes ex vivo/in vitro from healthy individuals and MGUS patients: protection by myricetin bulk and nanoforms

New insights into the oxidative and cytogenotoxic effects of Tetraglyme on human peripheral blood cells

The present study investigated the oxidative and cytogenotoxic potential of Tetraethylene glycol dimethyl ether (known as Tetraglyme) on healthy human peripheral blood lymphocytes, widely used as an in vitro model for assessing the human health risk posed by different chemical compounds. In a first step, Nuclear Magnetic Resonance (1H NMR) spectroscopy, and Ultra-High Performance Liquid Chromatography-Mass Spectrometry (UHPLC-MS) were employed to estimate Tetraglyme's stability under a wide range of pH values (4-12), and thus to identify potential by-products. Thereafter, isolated lymphocytes were treated with different concentrations of Tetraglyme (0.02-20 mg L-1) for assessing its oxidative (using the DCFH-DA staining), and cytogenotoxic potential (using the trypan blue exclusion test for estimating cell viability, Comet assay, as well as the cytokinesis-block micronucleus assay, with or without the addition of S9 metabolic activation system). According to the results, Tetraglyme remains stable at pH 4, but two additional derivatives (i.e. 1-[2-(2-ethoxyethoxy)ethoxy]-2-methoxyethane [C9H20O4] and 1-ethoxy-2-(2-ethoxyethoxy)ethane (Diethylene glycol diethyl ether) [C8H18O3]) were found in traces, under alkaline conditions (pH ≥7). Moreover, although Tetraglyme (and/or its derivatives) showed negligible alterations of cell viability (>92 %) in all cases, the pronounced ROS formation, DNA damage, cell proliferation arrest, and MN frequencies in challenged cells are indicative of its oxidative and cytogenotoxic potential. The significant alterations of Cytokinesis-Block Proliferation Index (CBPI) and Micronucleus (MN) frequencies in S9 challenged cells give further evidence for the potential involvement of Tetraglyme's metabolites in the observed cytogenotoxic mode of action. Although not conclusive, the present findings give rise to further research, utilizing different cell types and biological models, for elucidating Tetraglyme's toxic mode of action, as well as its environmental and human risk.

Dietary Polyphenols: Review on Chemistry/Sources, Bioavailability/Metabolism, Antioxidant Effects, and Their Role in Disease Management

Polyphenols, as secondary metabolites ubiquitous in plant sources, have emerged as pivotal bioactive compounds with far-reaching implications for human health. Plant polyphenols exhibit direct or indirect associations with biomolecules capable of modulating diverse physiological pathways. Due to their inherent abundance and structural diversity, polyphenols have garnered substantial attention from both the scientific and clinical communities. The review begins by providing an in-depth analysis of the chemical intricacies of polyphenols, shedding light on their structural diversity and the implications of such diversity on their biological activities. Subsequently, an exploration of the dietary origins of polyphenols elucidates the natural plant-based sources that contribute to their global availability. The discussion extends to the bioavailability and metabolism of polyphenols within the human body, unraveling the complex journey from ingestion to systemic effects. A central focus of the review is dedicated to unravelling the antioxidant effects of polyphenols, highlighting their role in combating oxidative stress and associated health conditions. The comprehensive analysis encompasses their impact on diverse health concerns such as hypertension, allergies, aging, and chronic diseases like heart stroke and diabetes. Insights into the global beneficial effects of polyphenols further underscore their potential as preventive and therapeutic agents. This review article critically examines the multifaceted aspects of dietary polyphenols, encompassing their chemistry, dietary origins, bioavailability/metabolism dynamics, and profound antioxidant effects. The synthesis of information presented herein aims to provide a valuable resource for researchers, clinicians, and health enthusiasts, fostering a deeper understanding of the intricate relationship between polyphenols and human health.

DNA Damage and Radiosensitivity in Blood Cells from Subjects Undergoing 45 Days of Isolation and Confinement: An Explorative Study

The effect of confined and isolated experience on astronauts’ health is an important factor to consider for future space exploration missions. The more confined and isolated humans are, the more likely they are to develop negative behavioral or cognitive conditions such as a mood decline, sleep disorder, depression, fatigue and/or physiological problems associated with chronic stress. Molecular mediators of chronic stress, such as cytokines, stress hormones or reactive oxygen species (ROS) are known to induce cellular damage including damage to the DNA. In view of the growing evidence of chronic stress-induced DNA damage, we conducted an explorative study and measured DNA strand breaks in 20 healthy adults. The participants were grouped into five teams (missions). Each team was composed of four participants, who spent 45 days in isolation and confinement in NASA’s Human Exploration Research Analog (HERA). Endogenous DNA integrity, ex-vivo radiation-induced DNA damage and the rates of DNA repair were assessed every week. Our results show a high inter-individual variability as well as differences between the missions, which cannot be explained by inter-individual variability alone. The ages and sex of the participants did not appear to influence the results.

Myricetin-Based Self-Assembled Nanoparticles for Tumor Synergistic Therapy by Antioxidation Pathway

Nanoplatforms are nano-scale systems that can transport different small molecular anticancer drugs or chemosensitization motif to accumulate in tumor cells without obvious side-effect in normal cells and achieve a synergistic therapy. In this paper the new self-assembled nanoparticles (NPs) merging doxorubicin (DOX) and myricetin (MYR) with ferric ions (Fe³⁺) and polyphenol was employed for forming the DOX@MYR-Fe³⁺ NP (FDMP NP). The FDMP NPs could reduce the DOX-induced toxicity in blood; and they could not cause damage to the heart and kidney tissues by the reasons that the MYR could enhance the anti-oxidation capability in normal cells, which resulted in preventing ROS-induced damage. Additionally, the FDMP NPs were characteristic of small size (37.70 ± 6.30 nm), high DOX loading efficiency (46.67 ± 1.58%), pH-controlled release and excellent stable pharmacokinetics, that inducing drug release and enhancing drug accumulation in the tumor. Moreover, the FDMP NPs could inhibit the expression of the hypoxia-inducible factor-1 α(HIF-1α) and the key angiogenesis mediator vascular endothelial growth factor (VEGF) both in vitro and in vivo, which succeed in preventing the generation of new blood vessel networks; that is the mechanism of the synergistic effect against tumors induced by FDMP NPs.

Anticancer potential of myricetin bulk and nano forms in vitro in lymphocytes from myeloma patients

Evading apoptosis and chemo-resistance are considered as very important factors which help tumour progression and metastasis. Hence, to overcome chemo-resistance, there is an urgent requirement for emergence of more effective treatment options. Myricetin, a naturally occurring flavonoid, is present in various plant-derived foods and shows antitumour potential in different cancers. In the present in vitro study, results from the comet assay demonstrated that myricetin bulk (10 µM) and nano (20 µM) forms exhibited a non-significant level of genotoxicity in lymphocytes from multiple myeloma patients when compared to those from healthy individuals. Western blot results showed a decrease in Bcl-2/Bax ratio and an increase in P53 protein levels in lymphocytes from myeloma patients, but not in lymphocytes from healthy individuals. A significant increase in intracellular reactive oxygen species level was also observed, suggesting that regulation of apoptotic proteins triggered by myricetin exposure in lymphocytes from myeloma patients occurred through P53 and oxidative stress-dependent pathways. The potency of myricetin against lymphocytes from myeloma patients marks it a potential candidate to be considered as an alternative to overcome chemo-resistance in cancer therapies.

Genome-Protecting Compounds as Potential Geroprotectors

Throughout life, organisms are exposed to various exogenous and endogenous factors that cause DNA damages and somatic mutations provoking genomic instability. At a young age, compensatory mechanisms of genome protection are activated to prevent phenotypic and functional changes. However, the increasing stress and age-related deterioration in the functioning of these mechanisms result in damage accumulation, overcoming the functional threshold. This leads to aging and the development of age-related diseases. There are several ways to counteract these changes: 1) prevention of DNA damage through stimulation of antioxidant and detoxification systems, as well as transition metal chelation; 2) regulation of DNA methylation, chromatin structure, non-coding RNA activity and prevention of nuclear architecture alterations; 3) improving DNA damage response and repair; 4) selective removal of damaged non-functional and senescent cells. In the article, we have reviewed data about the effects of various trace elements, vitamins, polyphenols, terpenes, and other phytochemicals, as well as a number of synthetic pharmacological substances in these ways. Most of the compounds demonstrate the geroprotective potential and increase the lifespan in model organisms. However, their genome-protecting effects are non-selective and often are conditioned by hormesis. Consequently, the development of selective drugs targeting genome protection is an advanced direction.

The Anticancer Drug 3-Bromopyruvate Induces DNA Damage Potentially Through Reactive Oxygen Species in Yeast and in Human Cancer Cells

3-bromopyruvate (3-BP) is a small molecule with anticancer and antimicrobial activities. 3-BP is taken up selectively by cancer cells’ mono-carboxylate transporters (MCTs), which are highly overexpressed by many cancers. When 3-BP enters cancer cells it inactivates several glycolytic and mitochondrial enzymes, leading to ATP depletion and the generation of reactive oxygen species. While mechanisms of 3-BP uptake and its influence on cell metabolism are well understood, the impact of 3-BP at certain concentrations on DNA integrity has never been investigated in detail. Here we have collected several lines of evidence suggesting that 3-BP induces DNA damage probably as a result of ROS generation, in both yeast and human cancer cells, when its concentration is sufficiently low and most cells are still viable. We also demonstrate that in yeast 3-BP treatment leads to generation of DNA double-strand breaks only in S-phase of the cell cycle, possibly as a result of oxidative DNA damage. This leads to DNA damage, checkpoint activation and focal accumulation of the DNA response proteins. Interestingly, in human cancer cells exposure to 3-BP also induces DNA breaks that trigger H2A.X phosphorylation. Our current data shed new light on the mechanisms by which a sufficiently low concentration of 3-BP can induce cytotoxicity at the DNA level, a finding that might be important for the future design of anticancer therapies.

Ex vivo/in vitro protective effect of myricetin bulk and nano-forms on PhIP-induced DNA damage in lymphocytes from healthy individuals and pre-cancerous MGUS patients

2-Amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) is a central dietary mutagen, produced when proteinaceous food is heated at very high temperatures potentially causing DNA strand breaks. This study investigates the protective potential of a well-researched flavonoid, myricetin in its bulk and nano-forms against oxidative stress induced ex vivo/in vitro by PhIP in lymphocytes from pre-cancerous monoclonal gammopathy of undetermined significance (MGUS) patients and those from healthy individuals. The results from the Comet assay revealed that in the presence of myricetin bulk (10 µM) and myricetin nano (20 µM), the DNA damage caused by a high dose of PhIP (100 µM) was significantly (P < 0.001) reduced in both groups. However, nano has shown better protection in lymphocytes from pre-cancerous patients. Consistent results were obtained from the micronucleus assay where micronuclei frequency in binucleated cells significantly decreased upon supplementing PhIP with myricetin bulk (P < 0.01) and myricetin nano (P < 0.001), compared to the PhIP treatment alone. To briefly determine the cellular pathways involved in the protective role of myricetin against PhIP, we studied gene expression of P53 and ATR kinase (ATM- and Rad3-related), using the real-time PCR technique.