Mercury: A Cancer Treatment?
Mercury (= Hydrargyrum) (Hg)
Potential anticancer agent?
Mercury belongs to the elements that are constantly present in the environment and living organisms. It may play a significant role in the human body.
The physiological effect of mercury is determined by its ability to participate in reversible reactions with functionally active groups of biomolecules (peptides, proteins).
The daily requirement for the human body is 1–5 µg. A deficiency of mercury in the body can develop with insufficient intake of this element (0.5 µg/day or less).
The mercury content in the human body is 13 mg. Mercury has been found in all organs and tissues of the human body. The toxicity of mercury depends on the chemical form in which it enters the body. Mercury (in liquid form) is generally non-toxic when it enters the body.
Toxic dose for humans – 0.4 mg. The toxicity threshold for mercury is 50 µg. The lethal dose for humans is 150–300 mg.
Toxic dose for humans – 0.4 mg. The toxicity threshold for mercury is 50 µg. The lethal dose for humans is 150–300 mg.
Elemental mercury in a suspended state is very well absorbed in the respiratory tract (up to 85–90%). Up to 52% of mercury is excreted in urine, and about 48% in feces. Inorganic compounds Hg2+ are absorbed in the gastrointestinal tract at about 10% of the amount ingested, with 60% excreted in urine and 40% in feces. Organic mercury compounds (alkylmercury and arylmercury compounds) are almost completely absorbed in the gastrointestinal tract (90%) and are mainly excreted from the body in feces (80%) and urine.
The maximum concentration of mercury is observed in the kidneys and is 2.7 µg/g of raw weight. In other tissues, this concentration is lower and equals 0.05–0.30 µg/g. Increased mercury content may be noted in hair (at 0.1–0.5 µg/g as normal), nails, and skin. The half-life of metallic mercury in humans is 70 days, organic mercury is 40 days, and vapors are 50 days.
Biological role in the human body. The physiological role of mercury has not been fully elucidated; however, it is believed to be determined by mercury’s ability to participate in reversible reactions with functionally active groups of peptides and proteins.
The maximum affinity of mercury for –SH (thiol, sulfhydryl) groups determines the preferential nature of their interaction. Thiol groups are the most important functional groups of proteins; they participate in the formation of their spatial structure and, accordingly, active sites by forming disulfide bonds (–S–S–) between cysteine residues in various regions of a single peptide chain or in separate peptide chains of a protein molecule.
When interacting with the active groups of proteins (primarily –SH groups) with mercury and its compounds used in physiological (biotic) concentrations, conformational changes in the protein molecule occur without the destruction of chemical bonds and therefore have a reversible nature. In these cases, the complementarity of the active sites of proteins to substrates and, accordingly, the rate of their interaction reactions can change either in the direction of increase – with the optimization of the spatial position of the groups of their active sites relative to the substrate – or in the direction of decrease – with a reduction in affinity for the substrate. Thus, the regulatory role of mercury in biochemical reactions is realized.
The maximum affinity of mercury for –SH (thiol, sulfhydryl) groups determines the preferential nature of their interaction. Thiol groups are the most important functional groups of proteins; they participate in the formation of their spatial structure and, accordingly, active sites by forming disulfide bonds (–S–S–) between cysteine residues in various regions of a single peptide chain or in separate peptide chains of a protein molecule.
When interacting with the active groups of proteins (primarily –SH groups) with mercury and its compounds used in physiological (biotic) concentrations, conformational changes in the protein molecule occur without the destruction of chemical bonds and therefore have a reversible nature. In these cases, the complementarity of the active sites of proteins to substrates and, accordingly, the rate of their interaction reactions can change either in the direction of increase – with the optimization of the spatial position of the groups of their active sites relative to the substrate – or in the direction of decrease – with a reduction in affinity for the substrate. Thus, the regulatory role of mercury in biochemical reactions is realized.
It has been established that sulema (mercury dichloride) in microdoses activates enzymes that regulate biological oxidation processes and, thus, increases the level of oxygen and energy supply to the body, which enhances cell viability and helps eliminate adverse metabolic changes that occur in almost any pathology, as well as increases the body’s resistance to the action of pathogenetic factors.
Even Jack London in the novels “Adventure” (1911) and “The Time Does Not Wait” (1910) mentions sulema as an ancient Eastern remedy for treating external tumors.
In recent years, close attention has been paid to the study of immunotropic properties of sulema (mercury dichloride). It has been experimentally proven that sulema, when introduced into the body in microdoses, causes a number of immunological phenomena: it stimulates the synthesis of immunoglobulins, enhances the cooperative interaction of T- and B-lymphocytes and the formation of interleukin-2, interferon, and contributes to maintaining a high level of cytotoxic T-lymphocytes capable of killing tumor cells. The results of these studies indicate that dichloride of mercury may serve as a highly effective multifunctional immunomodulator, and allow it to be considered as a potential anticancer agent.
Synergists and antagonists of mercury. Antagonists of mercury include pepsin, amino acids, selenium, zinc, sulfur, and vitamin C.
Signs of mercury deficiency: frequent colds, multiple inflammatory processes.
With excessive intake, mercury compounds are highly toxic.
Mercury usually enters the human body through the lungs or gastrointestinal tract. Mercury compounds are well soluble in lipids, thus easily penetrating through the alveolar membrane, intestinal wall, placental barrier, and skin.
In chronic mercury poisoning, a syndrome of mercurialism develops with disturbances in the activity of the nervous system and gastrointestinal tract, and the emergence of dermatoses (mercurialism of the skin). In Japan, a mass mercury poisoning of the population was described, which was named “Minamata disease”.
In chronic mercury poisoning, a syndrome of mercurialism develops with disturbances in the activity of the nervous system and gastrointestinal tract, and the emergence of dermatoses (mercurialism of the skin). In Japan, a mass mercury poisoning of the population was described, which was named “Minamata disease”.
Main manifestations of mercury excess: mental disorders; headaches, fatigue, anxiety, irritability, “mercurial encephalopathy” accompanied by disturbances of psyche and intellect; astheno-vegetative syndrome, cerebellar ataxia, visual and auditory disturbances, tremor of the hands, eyelids, lips, and the whole body, “mercurial” toxic dermatitis, diffuse rain-like rashes, sometimes of hemorrhagic nature, eczema, hair loss, brittle nails; labile pulse, tachycardia, high fever, “mercurial” stomatitis, gingivitis, edema, erosions, and ulcers of the mucous membrane of the oral cavity, necrosis of the jaw processes, tooth loss, “mercurial” ulcerative-necrotic gastroenteritis, gastralgia, colic, diarrhea, ulcers and necroses of the wall of the large intestine; ulcerative-necrotic nephrosonephritis, proteinuria, pain, disruption of excretory functions up to anuria; menstrual cycle disorders, miscarriages, intrauterine fetal death, changes in blood composition, hemolysis of erythrocytes, disruption of hematopoiesis, anemia with severe course.
Mercury is necessary: in inflammatory processes, decreased immunity, in tumors.