An alkaloid is ... Classification of alkaloids, characteristic

Since ancient times, people have used plant ingredients to relieve pain and get rid of diseases and ailments. However, the study of the component composition, the isolation of those compounds that have such an effect, became possible only with a broad and massive development of chemistry as a science, that is, since the XVII century.

It was then that in the bowels of plant organisms, and now even in some animals, nitrogen-containing organic compounds were discovered, which gave such a wide therapeutic effect. Since 1819 the general name of this group of substances is alkaloids. Proposed by Meissner, a pharmacist and a doctor.

What is an alkaloid?

At present, it is considered that an alkaloid is a cyclic compound containing one or more nitrogen atoms in the cycle or side chain and, in chemical nature, exhibiting the properties of a weak alkali, like ammonia. Earlier it was said about the determination of these substances as derivatives of the nitrogenous base of pyridine. However, a number of compounds of this group were later discovered, which showed that such an interpretation is not entirely true and does not cover the whole variety of alkaloids.

This substance was first obtained and investigated in 1803 by the scientist Derson. It was the morphia obtained from opium. Subsequently, independently of each other, many scientists discovered a number of complex heterocyclic compounds from plant material. So there was an idea that an alkaloid is a substance of predominantly natural origin. It is formed only in plants.

Chemical composition of molecules

In their chemical nature, these substances are nitrogen-containing organic compounds that contain nitrogen atoms in complex heterocycles, interconnected by different types of bonds and interactions.

From plants they are released in the composition of salts of some acids:

• Apple;
• Wine;
• Oxalic;
• Acetic and others.

If the pure substance is separated from the salt, it is possible to obtain an alkaloid in the form of a solid crystalline powder, or it can be in the form of a liquid structure (nicotine). In both cases, this is an alkaline compound exhibiting the corresponding chemical properties.

That is, the chemistry of alkaloids is known and studied. So, for example, the methods by which it is possible to isolate them from plant raw materials are defined. They are based on the solubility of alkaloid salts in water, since in pure form these compounds are almost insoluble in water, but they do this perfectly in organic solvents.

A number of reactions, by means of which the isolation and study of such compounds occurs, are called alkaloid.

1. Precipitation. Reactions based on the formation of an insoluble alkaloid salt that precipitates. This can be done if the following components are used: tannin, picric acid, phosphotungstic or molybdic acid.
2. Precipitation. Reactions based on the formation of complex complex salts involving alkaloid compounds. Reagents: mercuric chloride, potassium iodide or bismuth.
3. Staining. In these reactions, the form of the alkaloid changes and it becomes noticeable in the overall composition. The principle of action is the effect on heterocycles, the appearance of color. Reagents: nitric, sulfuric acid, copper (II) hydroxide freshly precipitated.

Often, staining reactions do not give exact results, since the heterocyclic composition of alkaloids is similar to that of protein molecules. Therefore, they give the same effect.

Classification of alkaloids

On what categories all known compounds of this group are subdivided, determines the kind of alkaloid, its chemical structure. Such a classification was created by Academician AP Orekhov and is based on the type and structure of the heterocycle with nitrogen atoms in them.

1. Pyrrolidine, pyrrolizidine and their derivatives. This group includes such alkaloids as platyphylline, sarracin, senicillin and others. The structure is based on complex five-membered heterocycles linked to each other, which contain a nitrogen atom.
2. Piperidine and pyridine, their derivatives. Representatives: anabasine, lobelin. The basis is six-complex cycles with nitrogen.
3. Quinolizidine and its compounds. This group includes: pachycarpine, thermopsin and others. Chemical basis in complex six-membered heterocycles, connected with each other and nitrogen.
4. The quinoline derivatives are quinine, echinopsin.
5. An important group of very common alkaloids is isoquinoline compounds. Salsalin, morphine and papaverine are widely used in medicine. Here you can also include alkaloids in the plants of barberry, mache and celandine.
6. Chemically very complex in structure tropane derivatives - hyoscyamine, atropine, scopolamine. The structure is represented by complex condensed, intertwined pyrrolidine and piperidine rings.
7. Indole and its compounds - reserpine, strychnine, vinblastine and others. A complex combination of five- and six-membered rings with nitrogen atoms in the structure.
8. The main alkaloid in the food industry and medicine is caffeine from tea leaves and the seeds of the cola plant. Refers to purine derivatives - complex compounds from different heterocycles and several nitrogen atoms in the composition.
9. Ephedrine and its compounds - spherofizin, colchicine and colchamine. The chemical name of ephedrine, reflecting its complex structure, phenylmethylaminopropanol is a complex organic aromatic alcohol.
10. Recently, it is customary to isolate into the alkaloids some substances of the group of steroids - corticosteroids and sex hormones.

Physical properties

The main properties of this group include the ability to dissolve in different liquids and the aggregate state under standard conditions.

At room temperature, an ordinary alkaloid is a solid crystalline substance. Colors and smell, as a rule, do not have. The taste is mostly bitter, astringent, unpleasant. They exhibit optical activity in solutions.

Some of these substances under standard fluid conditions are anoxic alkaloids, totaling about 200 species. For example, nicotine, pachycarpine, coneyin.

If we talk about the solubility in water, then only caffeine, ephedrine, ergometrine can do this. The remaining representatives of this class of compounds dissolve only in liquid organic substances (solvents).

Action on the human body

An alkaloid is a substance that has a strong effect on the human and animal body. What is this influence?

1. A huge impact is on the nervous system, the endings of nerve cells, synapses, neurotransmitter processes. On these areas of the body, various groups of alkaloids act as sedatives, psychotropic, reflex, antitussive, stimulants, narcotic drugs, analgesics. When properly used for medical purposes, strictly dosed and accurate, these effects are beneficial. However, the slightest overdose can lead to very serious and sad consequences.
2. Action on the cardiovascular system - antiarrhythmic, improves blood supply, spasmolytic, hypotensive, cholagogue.

In the event that preparations based on alkaloids are used not for their intended purpose or without compliance with the required dosage, the following consequences are possible:

• Impaired vision, hearing;
• Violation of breathing, heaviness in the chest;
• Dizziness, nausea, vomiting;
• bleeding;
• Dry mouth;
• A sharp increase or decrease in blood pressure;
• Severe fatal poisoning.

Much of the alkaloids, according to their physiological effects on humans, are poisons, strong, causing convulsions and death (strychnine, morphine, belladonna). The other part is narcotic compounds that cause addiction. Psychological, emotional and physical (nicotine, caffeine, cocaine). Therefore, with these compounds you need to behave very carefully and use only on the recommendation and prescription of the doctor.

Use in medicine

In this area, plants containing alkaloids - this is the basis for many drugs of a wide range of action, or, conversely, highly specialized. On the basis of such raw materials, candles, tinctures, tablets, ampoule solutions are obtained. The action is aimed at the treatment of cardiovascular diseases, respiratory organs, nervous system and endings, mental disorders. Also for the treatment of the digestive system, as contraceptives, with oncological diseases, for the elimination of alcohol dependence and many other areas.

Where are alkaloids in nature?

In natural conditions, alkaloids contain medicinal herbs and plants. Today, about 10,000 names of these substances are known, and almost all of them are extracted from such raw materials.

In parts of fungi, cells of bacteria, algae, echinoderms alkaloids were not found. Of the cells of some animals, compounds of alkaloid nature were extracted, but there are very few of them.

Thus, it turns out that the main supplier, an inexhaustible source of these substances for medical purposes, human life, industry - these are plants containing alkaloids.

Medicinal Herbs

What are these plants? There are, in fact, too many to mention everything. However, it can be called the most common and often used by man.

1. The flat-leafed flatulent - alkaloid platifillin and senescillin - spasmolytic and sedative effect on the body, is used to create appropriate medications.
2. A common bell beetle from the family Paslenov. A very important plant for medicine. Alkaloid belladonna - atropine and belladonna. Preparations based on the belladonna components excite the CNS, activate mental and physical activity, increase efficiency and endurance. Have an antispasmodic and analgesic effect. Based on the extract of this plant, medicinal drops, tinctures and suppositories were created.
3. Belenas is black. Completely poisonous plant, all its parts are dangerous. Alkaloids are hyoscyamine and scopolamine. They are used to treat neurological ailments and seasickness.
4. Purity is great. A very common plant on the territory of our country. However, it contains alkaloids quinolizidine, pachycarpine, saponin, thermopsin and others. Very toxic if used improperly.
5. Alkaloids in the plants of the Poppy family are estimated in two dozen. These are opium, morphine, narcotin, papaverine, thebaine, codeine and other isoquinoline derivatives. Their action and meaning will be considered separately.
6. Passiflora is meat-red. Contains a number of alkaloids, indole derivatives. Has a strong sedative effect.
7. Ergot. Specially created cultures of this fungus-parasite, which destroys the crops of rye, are used to obtain the strongest alkaloids. This is ergotamine and ergometrine, as well as 18 more varieties. Used in medicine (especially in gynecology).
8. Rauwolfia snake - the roots of this plant contain more than 50 alkaloids, used to treat cardiovascular diseases, hypertension including.

Medicinal herbs and plants are a very important area of modern medicine. After all, most of the preparations are synthesized on the basis of natural raw materials. They have been used since antiquity and have not lost their relevance to man today. On the contrary, over time people are increasingly trying to discover and study the component composition of such plants in order to find something important, something that will help solve the problem of many incurable diseases.

The most common alkaloid

This is the derivative of opium - codeine. It can be isolated by special chemical reactions from morphine. Compared with the latter, it is safer to use, because the action is soft. However, the effectiveness as an analgesic, antitussive, sedative is not at all worse than morphine or opium itself.

Therefore, codeine-based drugs are very widely used in medicine and are used by people of all countries. The only limitation is the dosage. It should be used only on the recommendation and under the supervision of a doctor.

Opium and its alkaloids

Opiates - so in medicine and chemistry it is customary to call all those alkaloids of opium that can be isolated from it and synthesized on its basis. What are these compounds? Unfortunately, today they are almost at everyone's ears and do not always have a good reputation and find a worthy, correct application. These are such alkaloids as:

• Morphine;
• papaverine;
• heroin;
• codeine.

In medicine, these substances are used, as antitussive, analgesic, sedatives. On the basis of codeine, even a number of drugs have been created for colds in children.

However, such compounds as opium and heroin are used not only for medical purposes, but also as heavy intoxicating drugs. They cause a terrible dependence of the human body and over time are capable of causing serious harm to health, even people's lives.