Ameliorative effect of certain antioxidants against mercury induced genotoxicity in peripheral blood lymphocytes

Guidance for the use and interpretation of assays for monitoring anti-genotoxicity

Since DNA damage can occur spontaneously or be produced by the environmental genotoxins in living cells, it is important to investigate compounds that can reverse or protect DNA damage. An appropriate methodology is essential for the responsive identification of protection offered against DNA damage. This review includes information on the current state of knowledge on prokaryotic cell-based assays (SOS chromotest, umu test, vitotox assay) and cytogenetic techniques (micronucleus assay, chromosome aberration test and sister chromatid exchange assay) with an emphasis on the possibility to explore genoprotective compounds. Throughout the last decade, studies have extrapolated the scientific methodologies utilized for genotoxicity to assess genoprotective compounds. Therefore, shortcomings of genotoxicity studies are also mirrored in antigenotoxicity studies. While regulatory authorities around the world (OECD, US-EPA and ICH) continue to update diverse genotoxic assay strategies, there are still no clear guidelines/approaches for efficient experimental design to screen genoprotective compounds. As a consequence, non-synergetic and inconsistent implementation of the test method by the researchers to execute such simulations has been adopted, which inevitably results in unreliable findings. The review has made the first attempt to collect various facets of experimentally verified approaches for evaluating genoprotective compounds, as well as to acknowledge potential significance and constraints, and further focus on the assessment of end points which are required to validate such action. Henceforth, the review makes an incredible commitment by permitting readers to equate several components of their test arrangement with the provided simplified information, allowing the selection of convenient technique for the predefined compound from a central repository.

Exposure of metal toxicity in Alzheimer’s disease: An extensive review

Metals serve important roles in the human body, including the maintenance of cell structure and the regulation of gene expression, the antioxidant response, and neurotransmission. High metal uptake in the nervous system is harmful because it can cause oxidative stress, disrupt mitochondrial function, and impair the activity of various enzymes. Metal accumulation can cause lifelong deterioration, including severe neurological problems. There is a strong association between accidental metal exposure and various neurodegenerative disorders, including Alzheimer’s disease (AD), the most common form of dementia that causes degeneration in the aged. Chronic exposure to various metals is a well-known environmental risk factor that has become more widespread due to the rapid pace at which human activities are releasing large amounts of metals into the environment. Consequently, humans are exposed to both biometals and heavy metals, affecting metal homeostasis at molecular and biological levels. This review highlights how these metals affect brain physiology and immunity and their roles in creating harmful proteins such as β-amyloid and tau in AD. In addition, we address findings that confirm the disruption of immune-related pathways as a significant toxicity mechanism through which metals may contribute to AD.

The protective effect of nano calcium produced from freshwater clam shells on the histopathological overview of the liver and kidneys of mice exposed to mercury toxins

BACKGROUND AND AIM

Freshwater clam shells nanoparticles powder is one of the uses of freshwater clams that can manufacture instant granular mineral supplements. This product can be used as a supplement to detoxify heavy metal toxins, such as Mercury. Mercury is an element that is detectable in all environmental media. Adults and children receive the most Mercury from food, air, and water intake. The majority of Mercury in the environment comes from the waste from mining activities and the metal industry. Mercury was found widely in the biosphere and is known as a dangerous hepatotoxicant. This study aimed to describe the hepatoprotective role of nano minerals (Ca, Mg, and Zn) produced from freshwater clam shells against mercury acetate poisoning in mice.

MATERIAL AND METHODS

The mice were divided randomly into a control group (aqua bidest and mercury acetate) and an experimental group for this purpose. The experimental mice group was given orally nano Ca supplementation in three dose groups (9 mg, 18 mg, and 27 mg/200 g animal body weight) once a day for 21 consecutive days. The mice are then given mercury acetate (1300 µg/200 g animal body weight intraperitoneally) on the 21st day. One hour after giving the nano Ca supplement, the mice's blood was taken. Liver and kidney were autopsied two days later to check quantitative and qualitative changes caused by mercury concentrations in liver and kidney histopathologies.

RESULTS

The results demonstrated the importance of nano Ca supplementation before mercury acetate induction, which has been shown to reduce necrotic depletion and hepatocyte degeneration.

CONCLUSION

Nano Ca supplementation has decreased the concentration of Hg in the blood of mice so that it can be used as a potential health supplement to detoxify mercury toxins.

Genotoxicity of Mercury and Its Derivatives Demonstrated In Vitro and In Vivo in Human Populations Studies. Systematic Review

Beside partial coverage in three reviews so far (1994, 2009, 2019), there is no review on genotoxic studies dealing with mercury (Hg) and human exposure using the most usual genotoxic assays: sister chromatid exchanges (SCE), chromosomal aberrations (CA), cytochalasin B blocked micronucleus assay (CBMN), and single-cell gel electrophoresis (SCGE or alkaline comet assay). Fifty years from the first Hg genotoxicity study and with the Minamata Convention in force, the genotoxic potential of Hg and its derivatives is still controversial. Considering these antecedents, we present this first systematic literature overview of genotoxic studies dealing with Hg and human exposure that used the standard genotoxic assays. To date, there is not sufficient evidence for Hg human carcinogen classification, so the new data collections can be of great help. A review was made of the studies available (those published before the end of October 2021 on PubMed or Web of Science in English or Spanish language) in the scientific literature dealing with genotoxic assays and human sample exposure ex vivo, in vivo, and in vitro. Results from a total of 66 articles selected are presented. Organic (o)Hg compounds were more toxic than inorganic and/or elemental ones, without ruling out that all represent a risk. The most studied inorganic (i)Hg compounds in populations exposed accidentally, occupationally, or iatrogenically, and/or in human cells, were Hg chloride and Hg nitrate and of the organic compounds, were methylmercury, thimerosal, methylmercury chloride, phenylmercuric acetate, and methylmercury hydroxide.

Medicinal plants and natural products can play a significant role in mitigation of mercury toxicity

Mercury is a heavy metal of considerable toxicity. Scientific literature reveals various plants and plant derived natural products, i.e., phytochemicals, which can alleviate experimentally induced mercury toxicity in animals. The present review attempts to collate those experimental studies on medicinal plants and phytochemicals with ameliorative effects on mercury toxicity. A literature survey was carried out by using Google, Scholar Google, Scopus and Pub-Med. Only the scientific journal articles found in the internet for the last two decades (1998–2018) were considered. Minerals and semi-synthetic or synthetic analogs of natural products were excluded. The literature survey revealed that in pre-clinical studies 27 medicinal plants and 27 natural products exhibited significant mitigation from mercury toxicity in experimental animals. Clinical investigations were not found in the literature. Admissible research in this area could lead to development of a potentially effective agent from the plant kingdom for clinical management of mercury toxicity in humans.

Antigenotoxic effect of melatonin against mercuric chloride in human peripheral blood lymphocytes

Melatonin (MLT) is an extraordinary antioxidant, which plays an important role in reducing reactive oxygen species (ROS) by scavenging them directly or indirectly. Mercury (Hg) is a heavy metal, which induces cytogenetic alterations via various mechanisms, leading to genotoxicity. It induces genotoxicity by enhancing the ROS chiefly. In the present study, the antigenotoxic effect of MLT was evaluated against mercuric chloride (HgCl₂). All experiments were conducted in vitro in peripheral blood lymphocytes. Blood cultures were exposed to various concentrations of HgCl₂ (2.63, 6.57, and 10.52 microM) for 24 h to study a range of genotoxic parameters. MLT (0.2 mM) supplementation, alone and in combination with the high concentration of Hg, was administered to blood cultures for 24 h. Genotoxic parameters, such as chromosomal aberrations (CAs; structural aberrations (chromatid gaps and breaks, chromosomal gaps and breaks) and numerical aberrations), micronuclei (MNs), and comet assay, were evaluated and analyzed using suitable statistical analysis. Hg treatment revealed a significant increase in CAs, MNs, and comet length. Co-supplementation of MLT along with Hg showed marked protection of these genotoxic end points in treated cultures. In conclusion, our findings suggest that MLT protects against Hg-induced augmentation in genotoxic indices because of its antioxidant property.

Ameliorative effects of curcumin against lead induced toxicity in human peripheral blood lymphocytes culture

Lead, a heavy metal and multifaceted toxicant, is well studied for its distribution and toxicity in ecosystem, yet there is no consensus on its amelioration by any synthetic or phytochemical compounds. Curcumin, a known antioxidant and dietary element, is a well-known herb, for its therapeutic uses and having a wide spectrum of its beneficial properties against several adverse effects. Hence, the current study was taken into consideration to evaluate the ameliorative effects of curcumin (3.87 μM, i.e. 1.43 μg/ml) against lead acetate (doses: 10^-6 M, i.e. 0.379 μg/ml and 10^-4 M, i.e. 37.9 μg/ml, durations: 24 h and 69 h) induced genotoxicity and oxidative stress in human peripheral blood lymphocyte cultures (PBLC). On one hand, antigenotoxic and antioxidative potentials of curcumin against lead were simultaneously evaluated by the array of genotoxicity and oxidative stress indices. The result postulated that lead acetate showed dose- and duration-dependent increase in both genotoxicity and oxidative stress whereas curcumin, when added along with lead acetate, showed the significant amelioration in all genotoxic and oxidative stress-related indices. The study indicated that, due to alteration in antioxidant defense system, there is an adverse genotoxic effect of lead. On the other hand, curcumin, a potent antidote, can protect chromatin material against lead -mediated genotoxicity by balancing the activity of antioxidant defense system.