Xenobiotics - what is it? Classification and characterization
Xenobiotics isThe term used to refer to chemical compounds that are foreign to a living organism. The word has Greek roots. Literally translated, it means "alien life." Let us consider in more detail what isxenobiotics. Classificationthese substances will also be cited in the article.
As practice shows, increasing the concentration and biotransformation of xenobiotics in nature is indirectly or directly related to the economic activities of people. Once in the external environment, they can cause the death of organisms, changes in hereditary traits. Under the action of these compounds, the frequency of allergic reactions increases, metabolic and other processes occurring in natural ecosystems are disturbed.
Characteristics of xenobiotics
A key feature of these substances is their ability to exert a lasting effect.However, their concentrations may be insignificant. For example, serious changes in the children's body can be caused by the minimum content of hormone-like compounds in the prenatal period. Most xenobiotics are lipophilic (hydrophobic). They are able to penetrate through the membrane through diffusion, move in the blood using lipoproteins, accumulate in adipose tissue. Xenobiotics can enter the body through the digestive tract, lungs, skin.
Mechanisms of action
Xenobiotics iscompounds capable of:
- Change metabolism in cells or tissues. As a result, the natural processes in the body are disrupted, and certain symptoms manifest themselves.
- Influencing cellular DNA, changing genetic information. The result is a malignant transformation.
- Imitate the action of natural compounds, for example, hormones. This causes a violation of normal growth, development of tissues, organs, immune and nervous systems.
- Change the activity of protecting the body. In this case, the negative impact is manifested in immune modulation, expressed in the development of hypersensitivity,increasing the number of B-or T-lymphocytes, stimulating autoimmune processes.
In simple terms,xenobiotics istoxins. The most studied of their property is the effect of the endocrine system effectors. Most of them provoke certain environmentally dependent pathologies. However, among these compounds are medicinal (useful) xenobiotics. In general, the consequences of the influence of substances on the body are:
- Reproductive disorders.
- Malignant formations in the male reproductive system.
- Cancers of the breast.
- Inhibition of immunity.
- Hypertrophy of the thyroid gland.
- Disorder of psychomotor development in childhood.
Types of xenobiotics
Considered substances are divided into the following categories:
- Natural origin.
- Formed in the body under the influence of certain factors.
- Coming from the outside upon receipt, processing, storage of food.
The latter include:
- Food raw materials resulting from microbiological or chemical synthesis.
- Compounds coming in when creating source materials.
- Nutritional supplements.
- Compounds coming in contact with polymeric and other materials.
- Substances formed during cooking.
Such xenobiotics are high-molecular compounds of lipopolysaccharide, polypeptide or protein nature. They have antigenic properties. Today, more than 150 such toxins have been studied. Many of them are considered the most poisonous. The main xenobiotics of this group are: staphylococcal, cholera, diphtheria toxins, tetanotoxin, botulinum toxin. Bacterial substances affect various systems and organs of mammals, in particular, humans. As a rule, the main violations are noted in the work of the central nervous system, heart and blood vessels. Bacteria are able to produce toxins of relatively simple structure. These include, for example, butanol, acetaldehyde, formaldehyde.
Of particular interest in practical terms are compounds produced by microscopic fungi. They can contaminate food. Some of these substances include some ergotoxins. They are produced by mushrooms from the Claviceps group. In addition, the composition of mycotoxins includes aflatoxins, as well as compounds close to them. They are distinguished by Aspergillus mushrooms.Substances that are analogues of ergotamine, affect the central nervous system, cause spasms in the vessels, contractions of the muscles of the uterus. In earlier times, poisoning by grain caused by ergot was often epidemic in nature. Today, the mass incidence is almost not detected, but the damage of cattle is likely. Toxic substances are produced by many higher fungi. These compounds have a wide spectrum of activity. The most dangerous include the Amanin, Amanitin, Phalloidin, present in the pale toadstool. If you accidentally use this fungus affects the kidneys and liver. Among other known toxic compounds can be noted muscarine, ibonetovoy acid, giromitrin. Some mushrooms synthesize substances with high hallucinogenic activity.
A large number of compounds that are dangerous to humans and animals, produced by plants. Speaking in the quality of metabolic products, phytotoxins often perform the functions of protection. But mostly their tasks remain unknown. Phytotoxins - substances with different biological activity and structure.These include organic acids, saponins, glycosides, terpenoids, coumarins, flavonoids, alkaloids, etc. Many compounds of plant origin are used in medicine. These substances, in particular, include galantamine, atropine, digitoxin, strophanthin, physostigmine, etc. Some phytotoxins are addictive. Among them, nicotine, cocaine, morphine, harmine, etc. A number of phytotoxins are carcinogenic. Separate compounds are present in cultures in small quantities and can have an effect in the composition of specially prepared preparations.
In any living organism, a large number of active compounds are synthesized. After isolation, processing and introduction into other organisms, they can provoke severe intoxication. Hazardous substances are present in the tissues of some animals. This allows them to be attributed to a special group of poisonous creatures. Individual animals are considered secondary dangerous. They do not produce, but accumulate poisons that come from outside. Such creatures include, for example, mollusks accumulating saxitoxin produced by unicellular organisms.Separate groups of compounds produced by animals are considered passive zootoxins. They are activated when the carrier is eaten.
Of particular importance among numerous substances are metals, their compounds, pollutants of the external environment and air in production areas. Under natural conditions, the former are found in the form of minerals and ores. They are found in water, soil, air. The content of toxic compounds has increased significantly due to human activity (smelting metal from ores). Mercury, arsenic, zinc, lead, thallium, copper, beryllium, chromium, cadmium, etc. have the highest toxicity. The latter is today regarded as one of the most dangerous xenobiotics. Despite its toxicity, mercury is widely used in the production of fungicides and the electronics industry. In the past, epidemics of poisoning with this compound were commonplace in pulp and paper mills. Beryllium is used in metallurgy. Lead is also widely used in business. Recently, its concentrations in the environment have become very high.