From ancient times, people used herbal ingredients to relieve pain and get rid of diseases and ailments. However, the study of just the component composition, the isolation of those compounds that have such an effect, became possible only with the widespread and massive development of chemistry as a science, that is, starting from the 17th century.
It was then that in the bowels of plant organisms, and today already in some animals, found nitrogen-containing organic compounds, which gave such a wide therapeutic effect. Since 1819, the common name for this group of substances is alkaloids. Suggested by W. Meisner, pharmacist and physician.
What is an alkaloid?
At present, it is generally accepted that an alkaloid is a cyclic compound that contains one or more nitrogen atoms in the composition of the cycle or side chain and, by its chemical nature, exhibits weak alkali properties, such as ammonia. Previously, the definition of these substances as derivatives of the nitrogenous base of pyridine was discussed. However, a number of compounds of this group were later discovered, which showed that such an interpretation is not entirely correct and does not cover the entire variety of alkaloids.
For the first time, this substance was obtained and studied in 1803 by the scientist Derson. It was morphine derived from opium. Subsequently, independently of each other, many scientists discovered a number of complex heterocyclic compounds from plant materials. So there was an idea that the alkaloid is a substance mainly of natural origin. It is formed only in plants.
The chemical composition of the molecules
By 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.
They are distinguished from plants in the composition of salts of certain acids:
- apple
- wine;
- oxalic;
- vinegar and others.
If the pure substance is separated from the salt, then you can get the alkaloid in the form of a solid crystalline powder, or in the form of a liquid structure (nicotine). In both cases, it is an alkaline compound that exhibits the corresponding chemical properties.
That is, the chemistry of alkaloids is known and studied. For example, methods have been identified by which they can be isolated from plant materials. They are based on the solubility of alkaloids in water, since in their pure form, these compounds in water are almost insoluble, but they do it perfectly in organic solvents.
A number of reactions by which the isolation and study of such compounds occur are called alkaloids.
- Precipitation. Reactions based on the formation of an insoluble alkaloid salt which precipitates. This can be done if you use the following components: tannin, picric acid, phosphoric tungsten or molybdenum acid.
- Precipitation. Reactions based on the formation of complex complex salts with the participation of alkaloid compounds. Reagents: mercury chloride, potassium or bismuth iodide.
- Staining. In these reactions, the type of 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 accurate results, since the heterocyclic composition of alkaloids is similar to that of protein molecules. Therefore, they give the same effect.
Classification of alkaloids
What categories all known compounds of this group are divided into, determines the type of alkaloid, its chemical structure. Such a classification was created by academician A.P. Orekhov and is based on the type and structure of a heterocycle with nitrogen atoms in them.
- Pyrrolidine, pyrrolisidine and their derivatives. This group includes alkaloids such as platifillin, sarracin, senecifillin and others. The structure is based on complex five-membered heterocycles connected to each other, which include a nitrogen atom.
- Piperidine and pyridine, their derivatives. Representatives: anabazine, lobelin. The basis is six-membered complex cycles with nitrogen.
- Quinolisidine and its compounds. This group includes: pachycarpin, thermopsin and others. The chemical base in complex six-membered heterocycles connected to each other and nitrogen.
- Quinoline derivatives - quinine, echinopsin.
- An important group of very common alkaloids is isoquinoline compounds. Salsalin, morphine and papaverine are widely used in medicine. This also includes alkaloids in plants of barberry, fly fly and celandine.
- Derivatives of tropane chemically very complex in structure are hyoscyamine, atropine, scopolamine. The structure is represented by complex condensed, intertwined pyrrolidine and piperidine rings.
- Indole and its compounds - reserpine, strychnine, vinblastine and others. A complex combination of five- and six-membered rings with nitrogen atoms in the structure.
- The main alkaloid in the food industry and medicine is caffeine from tea leaves and cola seeds. Refers to purine derivatives - complex compounds from different heterocycles and several nitrogen atoms in the composition.
- Ephedrine and its compounds are spherophysin, colchicine and colchamine. The chemical name of ephedrine, reflecting its complex structure, phenylmethylaminopropanol is a complex organic aromatic alcohol.
- Recently, it has been customary to isolate certain substances of the steroid group — corticosteroids and sex hormones — into alkaloids.
Physical properties
The main properties of this group include the ability to dissolve in different liquids and the state of aggregation under standard conditions.
At room temperature, a common alkaloid is a crystalline solid. Colors and odors, as a rule, do not have. The taste is mainly bitter, astringent, unpleasant. They exhibit optical activity in solutions.
Some of these substances under standard liquid conditions are oxygen-free alkaloids, in total about 200 species. For example, nicotine, pachycarpine, koniin.
If we talk about solubility in water, then only caffeine, ephedrine, ergometrine can do this completely. The remaining representatives of this class of compounds are soluble only in liquid organic substances (solvents).
Action on the human body
An alkaloid is a substance that has a strong effect on the human body and animals. What is this influence?
- A huge impact is on the nervous system, nerve cell endings, synapses, neurotransmitter processes. Different groups of alkaloids act on these areas of the body as sedatives, psychotropic, reflex nature, antitussive, stimulants, narcotic drugs, analgesics. When used correctly for medical purposes, strictly dosed and accurate, these effects are beneficial. However, the slightest overdose can lead to very serious and sad consequences.
- The effect on the cardiovascular system is antiarrhythmic, improves blood supply, antispasmodic, hypotensive, choleretic.
In the event that alkaloids-based preparations are used for other purposes or without compliance with the required dosage, the following consequences are possible:
- impaired vision, hearing;
- respiratory failure, heaviness in the chest;
- dizziness, nausea, vomiting;
- bleeding;
- dry mouth
- a sharp increase or decrease in blood pressure;
- severe fatal poisoning.
A significant part of alkaloids in their physiological effect on humans is poisons, strong, causing convulsions and death (strychnine, morphine, belladonna). The other part is addictive narcotic compounds. Psychological, emotional and physical (nicotine, caffeine, cocaine). Therefore, with these compounds you need to behave extremely carefully and use only on the recommendation and prescription of a doctor.
Use in medicine
In this area, plants containing alkaloids are the basis for many drugs with a wide spectrum 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, for oncological ailments, to eliminate alcohol dependence and many more other directions.
Where are alkaloids found in nature?
In vivo, alkaloids contain herbs and plants. Today, about 10,000 names of these substances are known and almost all of them are extracted from just such raw materials.
In parts of fungi, bacterial cells, algae, echinoderms alkaloids were not found. Alkaloid compounds were extracted from the cells of some animals, 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 plants
What kind of plants are these? In fact, there are too many of them to mention everything. However, you can name the most common and often used by man.
- Flat-headed godson — the alkaloid platifillin and senecifillin — an antispasmodic and sedative effect on the body, is used to create appropriate medications.
- Belladonna vulgaris from the nightshade family. A very important plant for medicine. Belladonna alkaloid - atropine and belladonna. Preparations based on belladonna components excite the central nervous system, activate mental and physical activity, increase working capacity and endurance. They have antispasmodic and analgesic effects. Based on the extract of this plant, medicinal drops, tinctures and candles are created.
- Belena is black. Completely poisonous plant, all its parts are dangerous. Alkaloids - hyoscyamine and scopolamine. Used for the treatment of neurological ailments and with motion sickness.
- Celandine is big. A very common plant in our country. However, it contains alkaloids quinolizidine, pachycarpine, saponin, thermopsin and others. Very toxic if used improperly.
- The alkaloids in plants of the poppy family are estimated at two dozen. These are opium, morphine, narcotine, papaverine, thebaine, codeine and other derivatives of isoquinoline. We will consider their effect and significance separately.
- Passiflora is meat red. Contains a number of alkaloids derived from indole. It has a strong sedative effect.
- Ergot. Specially created cultures of this parasite fungus that destroys rye crops are used to produce the strongest alkaloids. These are ergotamine and ergometrine, as well as another 18 varieties. Used in medicine (especially in gynecology).
- Rauwolfia snake - the roots of this plant contain more than 50 alkaloids used to treat cardiovascular diseases, including hypertension.
Medicinal herbs and plants are a very important area of modern medicine. After all, most of the drugs are synthesized on the basis of natural raw materials. They have been used since antiquity and have not lost their relevance to humans today. On the contrary, over time, people are increasingly seeking 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
Such is considered a derivative of opium - codeine. It can be distinguished by special chemical reactions from morphine. Compared with the latter, it is safer to use, as it is mild in action. However, the effectiveness as an analgesic, antitussive, sedative is not worse than that of morphine or opium itself.
Therefore, codeine-based drugs are very widespread 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 - as it is customary in medicine and chemistry to call all those opium alkaloids that can be isolated from it and synthesized on its basis. What are these compounds? Unfortunately, today they are almost at everyone's hearing and do not always have good fame and find worthy, proper application. These are alkaloids such as:
- morphine;
- papaverine;
- heroin;
- codeine.
In medicine, these substances are used as antitussive, painkillers, sedatives. On the basis of codeine, even a number of drugs have been created for colds in children.
However, compounds such 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.