Uric acid formula. Uric acid structural formula. Uric acid metabolism scheme

What is uric acid? It is a constituent not only of urine, but also of blood. It is a marker of purine metabolism. Its concentration in the blood helps specialists diagnose a number of diseases, including gout. Based on the indicator of the level of this element in the blood, it is possible to monitor the body's response to treatment.

What is this element?

In the human body, metabolic processes are constantly going on. The exchange can result in salts, acids, alkalis and many other chemical compounds. To get rid of them, they need to be delivered to the appropriate department of the body. This task is performed with the help of blood, which is filtered by the kidneys. Thus, the presence of uric acid in the urine is explained.

Let's see what it is in more detail. Uric acid is an end product of breakdown purine bases... These elements enter the body along with food. Purines are involved in the synthesis process nucleic acids(DNA and RNA), energy ATP molecules, as well as coenzymes.

It should be noted that purines are not the only source of uric acid formation. It can be the result of the breakdown of body cells due to illness or old age. Synthesis in any cell of the human body can become a source for the formation of uric acid.

The breakdown of purines occurs in the liver and intestines. The cells of the mucous membrane secrete a special enzyme - xanthine oxidase, with which purine reacts. The end result this "transformation" is acid.

It contains sodium and calcium salts. The share of the first component is 90%. In addition to salts, this includes hydrogen, oxygen, nitrogen and carbon.

If uric acid is higher than normal, this indicates a violation of the metabolic process. As a result of such a failure in humans, salt is deposited in the tissues, and as a result, serious diseases develop.

Uric acid functions

Despite the fact that excess uric acid can cause significant harm to the body, you still cannot do without it. She performs protective functions and has beneficial properties.

For example, in the process of protein metabolism, it acts as a catalyst. Its influence extends to the hormones responsible for brain activity- adrenaline and norepinephrine. This means that its presence in the blood helps to stimulate the brain. Its action is similar to caffeine. People who have high levels of uric acid in their blood from birth are more active and proactive.

It has acid and antioxidant properties to help heal wounds and fight inflammation.

Uric acid in the human body has protective functions. She fights free radicals. As a result, the risk of the appearance and development of benign and cancerous tumors is reduced.

Delivery of analysis

Such an analysis is prescribed to determine the patient's state of health, as well as to diagnose a disease that could cause an increase in the level of uric acid in the blood. To obtain true results, you must first prepare for donating blood.

You cannot eat 8 hours before visiting the laboratory, the sampling of biomaterial is carried out on an empty stomach. Spicy, salty and peppery foods, meat and offal, legumes should be excluded from the menu. This diet should be followed 24 hours before donating blood. During the same period, you need to stop drinking alcoholic beverages, especially wine and beer.

More uric acid than normal may be due to stress, emotional stress, or physical activity on the eve of the test.

Diuretic drugs, vitamin C, caffeine, beta-blockers and ibuprofen can also distort the results. If it is impossible to refuse such medications, then the doctor should be warned before taking the analysis.

The laboratory will take deoxygenated blood... The research results are prepared within 24 hours.

The rate of uric acid in the blood test

If the obtained results of biochemical analysis showed figures corresponding to the data given in the table below, then everything is normal.

Age category (years) Norms of uric acid (μmol / l)
Children under 12 120-330
Up to 60 Men 250-400
Women 200-300
From 60 Men 250-480
Women 210-430
From90 Men 210-490
Women 130-460

As can be seen from the table, the level rises with age. Highest value in older men, this is the rate of uric acid in the blood, since the need for proteins in male body above. This means that they consume more foods rich in purine and, as a result, increased uric acid in the blood.

What can cause deviations from the norm?

The level of uric acid in the blood depends on the balance of 2 processes:

  • Protein synthesis;
  • Intensity of excretion of end products of protein metabolism.

When a disorder of protein metabolism occurs, it can provoke an increase in the content of this acid in the blood. Plasma uric acid concentrations above the normal range are referred to as hyperuricemia, and below normal levels as hypouricemia. Above and below normal uric acid concentrations in urine are known as hyperuricosuria and hypouricosuria. Salivary uric acid levels may be related to blood uric acid levels.

Causes of hyperuricemia:

  • Taking diuretics (diuretics);
  • Decrease in the intensity of excretion of substances by the kidneys;
  • Toxicosis;
  • Alcoholism;
  • Renal failure;
  • Malnutrition or prolonged fasting.

Overestimated content can also occur in diseases such as AIDS, diabetes, cancer, etc.

It is worth noting that even a slightly increased level of this substance can cause the formation of solid deposits of uric acid salts - urates - in organs and tissues.

Increased rate

Now we will find out why uric acid in the blood is increased: causes, symptoms and consequences.

In medicine, hyperuricemia is divided into two types: primary and secondary.

Primary hyperuricemia

This type is congenital or idiopathic. A similar pathology occurs with a frequency of 1%. In such patients, there is a hereditary defect in the structure of the enzyme, which affects the processing of purine. As a result, there is high content uric acid in the blood.

The emergence of secondary hyperuricemia can occur due to malnutrition. Eating large amounts of foods containing purine can significantly increase urinary excretion of uric acid.

Hyperuricemia of this type can be associated with the following conditions:

Gout is a painful condition caused by needle-like uric acid crystals deposited in joints, capillaries, skin and other tissues. Gout can occur if the serum uric acid level reaches 360 μmol / L, but there are times when the serum uric acid value reaches 560 μmol / L, but does not cause gout.

V human body purines are metabolized to uric acid, which is then excreted in the urine. Regular consumption of certain types of purine-rich foods - meat, especially beef and pork liver (liver, heart, tongue, kidneys) and certain types of seafood, including anchovies, herring, sardines, mussels, scallops, trout, haddock, mackerel and tuna. There are also products, the use of which is less dangerous: turkey, chicken and rabbit. Moderate intake of purine-rich vegetables is not associated with increased risk gout. Gout used to be called the "disease of kings" because gourmet meals and red wine contain a large number of purines.

Lesch-Nihan syndrome

This extremely rare inherited disorder is also associated with high serum uric acid levels. In this syndrome, spasticity, involuntary movement and cognitive retardation are observed, as well as manifestations of gout.

Hyperuricemia May Increase Risk Factors for Cardiovascular Disease

Stones in the kidneys

Saturation levels of uric acid in the blood can lead to one form of kidney stones when urates crystallize in the kidneys. Crystals acetic acid may also promote the formation of calcium oxalate stones by acting as "seed crystals"

Kelly-Sigmiller Syndrome;

Increased activity of the synthesis of phosphoribosyl pyrophosphate synthetase;

Patients with this condition do biochemical analysis to increase uric acid annually.

Secondary hyperuricemia

This phenomenon can be a sign of such diseases:

  • AIDS;
  • Fanconi syndrome;
  • Cancerous tumors;
  • Diabetes mellitus (Hyperuricemia may be due to insulin resistance in diabetes, rather than its precursor);
  • High degree burns;
  • Hypereosinophilia syndrome.

There are other reasons for the increase in uric acid - a violation in the functioning of the kidneys. They cannot remove excess acids from the body. As a result, kidney stones may appear.

A high level of uric acid is observed with such diseases:

  • Pneumonia;
  • Methyl alcohol poisoning;
  • Eczema;
  • Typhoid fever;
  • Psoriasis;
  • Erysipelas;
  • Leukemia.

Asymptomatic hyperuricemia

There are cases when the patient has no symptoms of the disease, and the indicators are increased. This state called asymptomatic hyperuricemia. It occurs in acute gouty arthritis. The indicators for this disease are unstable. At first, the acid content seems to be normal, but after a while the numbers may increase by 2 times. In this case, these differences in the patient's well-being are not reflected. This course of the disease is possible in 10% of patients.

Symptoms of hyperuricemia

With hyperuricemia, symptoms in various age groups are different.

In very young children, the disease manifests itself in the form skin rashes: diathesis, dermatitis, allergy or psoriasis. The peculiarity of such manifestations is resistance to standard methods therapy.

In older children, the symptoms are somewhat different. They may have abdominal pain, incoherent speech, and enuresis.

The course of the disease in adults is accompanied by joint pain. The first to enter the affected area are the feet and joints of the fingers. Then the disease spreads its effect to the knee and elbow joints... In advanced cases, skin covering over the affected area turns red and becomes hot. Over time, patients begin to feel pain in the abdomen and lower back during urination. If measures are not taken in a timely manner, the vessels and the nervous system will suffer. The person will be tormented by insomnia and headache... All this can lead to heart attack, angina pectoris and arterial hypertension.

Treatment

Some specialists prescribe medications to keep uric acid in the blood normal. But a certain food diet for the rest of his life is more effective method treatment.

If the patient has been found to have hyperuricemia, treatment includes dietary intake. The patient's diet additionally includes:

Carrot juice;

Birch juice;

Flax seed;

Celery juice;

Oat broth;

Cranberry juice;

Rosehip infusion.

These herbal infusions and juices contribute the fastest dissolution and washing out the salt sediment from the body.

Fatty, meat broths, fried, salted, smoked and pickled foods are excluded. Meat can only be eaten boiled or baked. It is recommended to give up the use of meat broths, since purines during their preparation pass from meat to broth. Restriction on the intake of meat - 3 times a week.

Under special ban alcoholic drinks... V exceptional cases, you can only 30 g of vodka. Beer and red wine are especially contraindicated.

Prefer alkaline mineral water.

Salt intake should be kept to a minimum. Ideally, it is better to give it up altogether.

It is necessary to monitor the frequency of food intake. Fasting can only aggravate the patient's condition and increase the level of uric acid. Therefore, the number of meals per day should be 5-6 times. Fasting days spend better on fermented milk products and fruits.

Some types of products should be excluded from the menu:

  • Sorrel;
  • Salad;
  • Tomatoes;
  • Grape;
  • Chocolate;
  • Eggs;
  • Coffee;
  • Cakes;
  • Turnip;
  • Eggplant.

Apples, potatoes, plums, pears, apricots contribute to a decrease in the level of uric acid. It should be monitored and monitored water balance- 2.5 liters of liquid per day should be drunk.

You can also treat high levels of acid in the blood with the help of physiotherapy procedures. So plasmapheresis will help cleanse the blood from excess salts. Should not be neglected and remedial gymnastics... A number of simple exercises (swinging legs, "cycling", walking on the spot, etc.) will help in stabilizing metabolism. Massage also helps break down the uric acid salt.

From drugs complexes with anti-inflammatory, diuretic and analgesic properties are prescribed. There are 3 types of drugs for hyperuricemia:

  1. Action aimed at removing excess uric acid: Probenecid, aspirin, sodium bicarbonate, allopurinol.
  2. Helping to reduce acid production. They are prescribed to patients who have had urolithiasis and those who have been diagnosed with renal failure;
  3. Helping to transfer uric acid from tissue into blood, and promoting its excretion: "Zinhoven".

The course of treatment includes diagnosis and elimination concomitant diseases and the factors that caused them. Thus, eliminating the causes that caused the increase in the level of uric acid in the blood. If uric acid in the blood is increased, then this negatively affects the human condition. Saline sediment settles on tissues and organs. The treatment for such a deviation is versatile: diet, physiotherapy, medication and ethnoscience... All these techniques in combination can help normalize acid levels.

It would seem that a substance such as uric acid is difficult to combine with blood. Here in the urine - another matter, there it is a place to be. Meanwhile, various metabolic processes are constantly going on in the body with the formation of salts, acids, alkalis and other chemical compounds that are excreted by urine and the gastrointestinal tract from the body, entering there from the bloodstream.

Uric acid (uric acid) is also present in the blood; it is formed in small amounts from purine bases. Necessary for the body purine bases mainly come from the outside, with food, and are used in the synthesis of nucleic acids, although in some quantities they are also produced by the body. As for uric acid, it is the final product purine metabolism and the body itself, in general, is not needed. Its increased level (hyperuricemia) indicates a violation of purine metabolism and can threaten with the deposition of salts unnecessary for a person in the joints and other tissues, causing not only unpleasant sensations, but also serious illnesses.

Uric acid rate and increased concentration

The norm of uric acid in the blood in men should not exceed 7.0 mg / dL (70.0 mg / L) or is in the range of 0.24 - 0.50 mmol / L. In women, the norm is slightly lower - up to 5.7 mg / dL (57 mg / L) or 0.16 - 0.44 mmol / L, respectively.

The MC formed during purine metabolism must dissolve in the plasma in order to further escape through the kidneys, but plasma cannot dissolve uric acid more than 0.42 mmol / L. With urine, 2.36 - 5.90 mmol / day (250 - 750 mg / day) is normally removed from the body.

At its high concentration, uric acid forms salt (sodium urate), which is deposited in tofuses (peculiar nodules) in different types tissues with an affinity for MK. Most often, tofus can be seen on auricles, hands, feet, but a favorite place are the surfaces of the joints (elbow, ankle) and tendon sheaths. In rare cases, they are able to merge and form ulcers, from which urate crystals emerge in the form of a white dry mass. Sometimes urates are found in bursae, causing inflammation, pain, limitation of mobility (synovitis). Uric acid salts can be found in bones with the development of destructive changes in bone tissue.

The level of uric acid in the blood depends on its production during purine metabolism, glomerular filtration and reabsorption as well as tubular secretion. Most often, an increased concentration of MK is a consequence of malnutrition, especially, this applies to people with hereditary pathology (autosomal dominant or X-linked fermentopathies), in which the production of uric acid in the body increases or its excretion slows down. Genetically determined hyperuricemia is called primary, secondary stems from a number of other pathological conditions or is formed by lifestyle influences.

Thus, we can conclude that The reasons for the increase in uric acid in the blood (excessive production or delayed excretion) are:

  • Genetic factor;
  • Improper nutrition;
  • Renal failure (impaired glomerular filtration, decreased tubular secretion - MC from the bloodstream does not pass into the urine);
  • Accelerated exchange of nucleotides (, lymph and myeloproliferative diseases, hemolytic).
  • The use of salicylic drugs, etc.

The main reasons for the increase ...

Medicine calls one of the reasons for the increase in uric acid in the blood improper nutrition, namely, the consumption of an unreasonable amount of products that accumulate purine substances. These are smoked meats (fish and meat), canned food (especially sprats), beef and pork liver, kidneys, fried meat dishes, mushrooms and all sorts of other delicacies. A great love for these products leads to the fact that necessary for the body purine bases are absorbed, and the final product, uric acid, turns out to be superfluous.

It should be noted that products of animal origin, which play an important role in increasing the concentration of uric acid, since they carry purine bases, as a rule, contain a large amount of cholesterol... Carried away by such favorite dishes, without observing measures, man can inflict Double punch according to your body.

The purine-depleted diet consists of dairy products, pears and apples, cucumbers (not pickled, of course), berries, potatoes and other fresh vegetables. Preservation, frying, or any "witchcraft" over semi-finished products noticeably impair the quality of food in this regard (the content of purines in food and the accumulation of uric acid in the body).

... And the main manifestations

Excess uric acid is carried throughout the body, where the expression of its behavior can have several options:

  1. Urate crystals are deposited and form microtofuses in cartilaginous, bone and connective tissue causing gouty diseases. Urates accumulated in cartilage are often released from tofuses. Usually, this is preceded by the effect of factors provoking hyperuricemia, for example, a new intake of purines and, accordingly, uric acid. Salt crystals are captured by leukocytes (phagocytosis) and are found in synovial fluid joints (synovitis). This is an acute attack gouty arthritis.
  2. Urates entering the kidneys can be deposited in the interstitial renal tissue and lead to the formation of gouty nephropathy, and then - and renal failure... The first symptoms of the disease can be considered a permanently low specific gravity of urine with the appearance of protein in it and an increase blood pressure (arterial hypertension), in the future there are changes in organs excretory system, pyelonephritis develops. The completion of the process is considered the formation renal failure.
  3. Increased content uric acid, salt formation(urates and calcium calculi) with its retention in the kidneys + increased acidity urine in most cases leads to the development kidney stone disease.

All movements and transformations of uric acid, which determine its behavior as a whole, can be interconnected or exist in isolation (as for whom it goes).

Uric acid and gout

Talking about purines uric acid, diet, it is impossible to ignore such unpleasant illness, how gout... In most cases, it is associated with MK, moreover, it is difficult to call it rare.

Gout mainly develops in mature males, sometimes it has a family character. Elevated level uric acid (hyperuricemia) is observed long before the onset of symptoms.

The first attack of gout is also bright clinical picture does not differ, only something - I got sick thumb a leg, and after five days the person again feels completely healthy and forgets about this annoying misunderstanding. The next attack can manifest itself after a long period of time and is more pronounced:

It is not easy to treat the disease, and sometimes it is not harmless for the body as a whole. Manifestation therapy pathological changes includes:

  1. At acute attack- colchicine, which reduces the intensity of pain, but tends to accumulate in white blood cells, hinder their movement and phagocytosis, and, therefore, participate in the inflammatory process. Colchicine inhibits hematopoiesis;
  2. Non-steroidal anti-inflammatory drugs - NSAIDs that have analgesic and anti-inflammatory effects, but negatively affect the organs of the digestive tract;
  3. Diacarb prevents stone formation (participates in their dissolution);
  4. The anti-gout drugs probenecid and sulfinpyrazone promote increased excretion of MK in the urine, but are used with caution when changes in urinary tract, in parallel, a large fluid intake, diacarb and alkalinizing drugs are prescribed. Allopurinol reduces the production of MK, contributes to the reverse development of tophuses and the disappearance of other symptoms of gout, therefore, this drug is probably one of the better means treating gout.

The patient can significantly increase the effectiveness of treatment if he takes a diet containing a minimum amount of purines (only for the needs of the body, and not for accumulation).

Diet for hyperuricemia

Low-calorie diet (table number 5 is best suited, if the patient's weight is okay), meat and fish - without fanaticism, 300 grams per week and no more. This will help the patient to lower the uric acid in the blood, to live full life without suffering from attacks of gouty arthritis. Patients with signs of this disease who have excess weight, it is recommended to use table number 8, not forgetting to unload every week, but at the same time remember that complete fasting is prohibited. Lack of food at the very beginning of the diet will quickly raise the level of MK and exacerbate the process. But about the additional admission ascorbic acid and B vitamins should be considered seriously.

All days, while the exacerbation of the disease lasts, should proceed without the use of meat and fish dishes. Food should not be solid, however, it is better to consume it altogether in liquid form (milk, fruit jelly and compotes, juices from fruits and vegetables, soups in vegetable broth, porridge - "smudge"). In addition, the patient should drink a lot (at least 2 liters per day).

It should be borne in mind that a significant amount of purine bases is found in delicacies such as:

In contrast, the minimum concentration of purines is found in:

This is a short list of foods that are prohibited or allowed for patients who find the first signs of gout and high uric acid in a blood test. The second part of the list (milk, vegetables and fruits) will help reduce uric acid in the blood.

Uric acid is lowered. What does this mean?

Uric acid in the blood is lowered, first of all, when using anti-gout drugs, which is absolutely natural, because they reduce the synthesis of MK.

In addition, a decrease in the level of uric acid can be a decrease in tubular reabsorption, a hereditary decrease in the production of MC and, in rare cases, hepatitis and anemia.

Meanwhile, reduced level the end product of the metabolism of purines (exactly, as well as increased) in the urine is associated with a wider range of pathological conditions, however, urine analysis for the content of MK is not so frequent, it is usually of interest to narrow specialists dealing with a specific problem. For self-diagnosis of patients, it is unlikely to be useful.

Video: uric acid in the joints, doctor's opinion

Uric acid - colorless crystals, poorly soluble in water, ethanol, diethyl ether, soluble in alkali solutions, hot sulfuric acid and glycerin.

Uric acid was discovered by Karl Scheele (1776) in the composition urinary stones and called by him stone acid - acide lithique, then it was found in his urine. The name of uric acid was given by Furcroix, its elemental composition was established by Liebig.

It is a diacid (pK1 = 5.75, pK2 = 10.3), forms acidic and medium salts - urates.

V aqueous solutions uric acid exists in two forms: lactam (7,9-dihydro-1H-purine-2,6,8 (3H) -trione) and lactam (2,6,8-trihydroxypurine) with a predominance of lactam:

It is readily alkylated first at the N-9 position, then at the N-3 and N-1 positions; under the action of POCl3, it forms 2,6,8-trichloropurine.

Uric acid is oxidized with nitric acid to alloxan, under the action of potassium permanganate in a neutral and alkaline medium or hydrogen peroxide from uric acid, allantoin is formed first, then hydantoin and parabanic acid.

Gorbachevsky was the first to synthesize uric acid in 1882 by heating glycocol (amidoacetic acid) with urea to 200-230 ° C.

NH2-CH2-COOH + 3CO (NH2) 2 = C5H4N4O3 + 3NH3 + 2H2O

However, this reaction is very difficult and the product yield is negligible. The synthesis of uric acid is possible through the interaction of chloroacetic and trichlorolactic acids with urea. The most clear mechanism is the synthesis of Berend and Roosen (1888), in which isodialuric acid is condensed with urea. Uric acid can be isolated from guano, where it contains up to 25%. To do this, guano must be heated with sulfuric acid (1 h), then diluted with water (12-15 h), filtered, dissolved in weak solution caustic potassium, filter, precipitate with hydrochloric acid.

The synthesis method consists in condensation of urea with cyanoacetic ether and further isomerization of the product to uramil (aminobarbituric acid), further condensation of uramil with isocyanates, isothiocyanates or potassium cyanate.

In humans and primates, it is the end product of purine metabolism resulting from the enzymatic oxidation of xanthine by xanthine oxidase; in other mammals, uric acid is converted to allantoin. Small amounts of uric acid are found in tissues (brain, liver, blood), as well as in the urine and sweat of mammals and humans. In some metabolic disorders, uric acid and its acidic salts (urates) accumulate in the body (kidney stones and bladder, gouty deposits, hyperuricemia). In birds, a number of reptiles, and most terrestrial insects, uric acid is the end product of not only purine, but also protein metabolism. The system of biosynthesis of uric acid (and not urea, as in most vertebrates) as a mechanism for binding in the body of a more toxic product of nitrogen metabolism - ammonia - developed in these animals due to their characteristic limited water balance (uric acid is excreted from the body with a minimum amount of water or even in solid). Dried bird excrement (guano) contains up to 25% uric acid. It has also been found in a number of plants. The increased content of uric acid in the human body (blood) is hyperuricemia. With hyperuricemia, point (similar to mosquito bites) manifestations of allergies are possible. The deposits of crystals of sodium urate (uric acid) in the joints are called gout.

Uric acid is a precursor for the industrial synthesis of caffeine. Synthesis of murexide.

Uric acid is the end product of purine metabolism; further purines do not break down.

Purines are necessary for the body for the synthesis of nucleic acids - DNA and RNA, energy ATP molecules and coenzymes.

Sources of uric acid:

  • - from food purines
  • - from decayed cells of the body - as a result of natural old age or disease
  • - uric acid can be synthesized by almost all cells of the human body

Every day a person consumes purines with food (liver, meat, fish, rice, peas). In the cells of the liver and intestinal mucosa, there is an enzyme - xanthine oxidase, which converts purines into uric acid. Despite the fact that uric acid is the end product of metabolism, it cannot be called "excess" in the body. It is necessary to protect cells from acid radicals, because it knows how to bind them.

The total "reserve" of uric acid in the body is 1 gram, 1.5 grams are excreted every day, of which 40% is of food origin.

The excretion of uric acid is provided by the kidneys by 75-80%, the remaining 20-25% - gastrointestinal tract where it is partially consumed by intestinal bacteria.

Uric acid salts are called urates, being the union of uric acid with sodium (90%) or potassium (10%). Uric acid is slightly soluble in water, and the body is 60% water.

Urates precipitate when the medium is acidified and the temperature drops. That is why the main pain points with gout - disease high level uric acid - are the distant joints (big toe), "bones" on the feet, ears, elbows. The onset of pain is provoked by cooling.

Increased acidity internal environment the body also occurs in athletes and with diabetes mellitus with lactic acidosis, which dictates the need to control uric acid.

The level of uric acid is measured in blood and urine. In sweat, its concentration is completely negligible and it is impossible to analyze it using publicly available methods.

The increased formation of uric acid directly in the kidneys occurs with alcohol abuse and in the liver - as a result of the exchange of certain sugars.

Uric acid in the blood is uricemia, and in the urine is uricosuria. An increase in uric acid in the blood is hyperuricemia, a decrease is hypouricemia.

Based on the level of uric acid in the blood, the diagnosis of gout is not made; symptoms and changes in X-rays are needed. If the uric acid in the blood is more than the norm, but there are no symptoms, the diagnosis is "Asymptomatic hyperuricemia". But, without the analysis of uric acid in the blood, the diagnosis of gout cannot be considered fully competent.

Norms of uric acid in the blood (in μmol / l)

newborns -140-340

children under 15 years old - 140-340

men under 65 - 220-420

women under 65 - 40-340

after 65 years - up to 500

In humans, it looks linear: purines → uric acid → urates → gout.

Let us consider the main factors in the development of the disease to determine the optimal treatment regimen for gout.

Uric acid(MK), as well as its salts - urates, which slowly dissolve in water with precipitation when they increased concentration in the blood (hyperuricemia) lead to the development of gout - a disease characterized by the deposition of crystals of uric acid and urate in the renal pelvis, joints, muscles with the formation of foci of inflammation.

Let's figure out how gout develops, let's define the terms and definitions associated with this disease.

Unorganized urine sediment is represented by salts precipitated in the form of crystals or amorphous masses. It can be uric acid, urates, phosphates, oxalates and other substances.

Uric acid (acide lithique) is caused by the breakdown of purines and nucleic acid by enzymes. It also removes excess purines from the human body, MC forms salts - urates. Interestingly, MK is used industrially for the production of caffeine. Acide lithique is a central stimulant nervous system(CNS) like coffee or tea;

Purines – chemical compounds containing non-protein nitrogen which are part of all living organisms. Purines are the basis of all nucleic acids such as DNA and RNA, i.e. purines are cell nuclei... In other words, purines are part of the structure of our gene. Purines enter the human body with food. Some foods have a higher purine content, others lower. Purine-containing foods are shown in the table below. When purines are naturally degraded by enzymes (digestion), they form uric acid, which in normal conditions acts as a powerful antioxidant. However, in patients with gout, the kidneys do not remove the breakdown product of purines - uric acid.

V different parts in meat products, the purine content is different depending on the intensity of muscle work. For example, there are more purines in chicken legs than in the breast. There are also more purines in the meat of predators. This pattern is also observed in fish, but the fat content of the product is not of great importance for a patient with gout, since purine and fat metabolism not related to each other. There are practically no purines in the egg white, in contrast to the yolk. There are also no purines in cottage cheese and not salted cheeses, milk. With the breakdown of purines, the structure of the nitrogenous base is preserved and oxidized to form uric acid, which is excreted in the urine;

Purines in foods are measured in mg per 100 grams of food.

Hyperuricemia- the content of uric acid in the human body is higher than normal;

Excretion- the process of removing waste products from the human body, harmful substances;

Reabsorption Is the transportation of substances (amino acids, glucose, vitamins, minerals) from the primary urine into the blood. The reabsorption process takes place in the renal tubules.

Stones. The stones have a layered structure and are a mixture of minerals and organics. Stones according to their chemical and physical properties can be subdivided into urates, oxalates, phosphates, to a lesser extent carbonates, cystine, xanthine, cholesterol and other stones.

Urata are crystals and stones formed from uric acid salts. The shape of the urates is round, the color is light yellow, less often red. Urates have a smooth outer surface and are slightly rough. Urata have enough high density... The diet for gout is aimed at alkalizing urine, urine pH should be above 5;

Oxalates Are salts of oxalic acid. Oxalates are round or rounded-elongated with a number of sharp spines. Oxalates have a dark brown color and a dense consistency.

Phosphates are stones composed of phosphate salts. Phosphates are white or gray. Phosphate consistency is loose.

Carbonates- stones containing calcium and magnesium carbonates. Stones white, soft.

Uric acid is eliminated from the human body mainly in urine and a little in feces. It is a weak acid and biological fluids is in non-dissociated form in a complex with proteins or in the form of monosodium salt - urate.

  • Normally, its concentration in blood serum is 0.15 - 0.47 mmol / l or 3-7 mg / dl.
  • From the body is excreted daily from 0.4 to 0.6 g of uric acid and urates.
  • Uric acid (UC) is present in human blood in the form of sodium monourate (urate);
  • Sodium monurate has a very low water solubility (0.57 mmol / l, 37 C)
  • With decreasing temperature, the solubility of MC decreases and vice versa;
  • Sodium monourate is lower in vegetarians;
  • In men, the content of uric acid in the blood is higher (0.42 mmol / l / 6.5 mg / 100 ml - the normal limit) than in women - 5.5 mg / 100 ml.
  • The content of MK, which causes the formation of gout, varies significantly among different ethnic groups;
  • Uric acid is increased in the blood in individuals with blood group B (III);
  • The content of acide lithique in the body is increased in persons with greater muscle mass;
  • The content of uric acid in the body is increased in persons with metabolic syndrome - obesity, atherosclerosis, hypertension, diabetes mellitus;
  • With age, the uric acid content increases;
  • Uric acid dissolves better and, accordingly, is excreted with an increase in urine alkalinity pH, i.e. with gout, you should reduce the consumption of "sour" foods: wine, beer, kvass, sour juices.
  • A person suffering from gout needs to improve the aeration of the body, to visit more fresh air doing breathing exercises, for example breathing exercises according to the Strelnikova method;
  • In the morning, uric acid in the blood is 4-10% more than in the evening;
  • 90% of the reason for the development of gout is a decrease in the excretion of urates, and only 10% of the development of gout is affected by an increase in the synthesis of urates from acide lithique;
  • Uric acid is a strong antioxidant, increased acide lithique causes smoking and UV exposure;
  • 85% of people with hyperuricemia do not develop gout.

Varieties of gout

  1. Renal gout is an increase in urate excretion;
  2. The metabolic type of gout is an increase in the formation and deposition of urate.

The standard for diagnosing gout is the detection of sodium urate crystals in joints or joint fluid with polarizing light microscopy. A study of the concentration of uric acid in the blood is not enough to make a diagnosis such as gout.

The diagnostic minimum for the development of gout:

  • Clinical blood test;
  • Lipidogram;
  • Blood glucose;
  • Urea, creatinine, uric acid;
  • Electrolytes;
  • General urine analysis;
  • ECG;
  • Ultrasound of the kidneys.

Acidic - alkaline balance, which must be taken into account when developing gout.

Below are the acids produced by the use of certain types food products and drinks, including alcoholic ones.

  • Acetic acid is formed from sweets;
  • From meat, sausages, canned food, uric acid, sulfuric and nitric acids are formed;
  • Tannic acid is obtained from coffee;
  • Carbon dioxide is obtained from lemonade;
  • Phosphoric acid is formed from coca-cola;
  • Wine, tartaric acid give sulfuric acid;
  • Cigarettes, nicotine form nicotinic acid;
  • Stress, anxiety is caused by an excess of hydrochloric acid;
  • Physical fatigue synthesizes lactic acid.

Hydroxy derivatives of purine are widespread in the plant and animal world, the most important of which are uric acid, xanthine, and hypoxanthine. These compounds are formed in the body during the metabolism of nucleic acids.

Uric acid... This crystalline substance, poorly soluble in water, is found in small amounts in the tissues and urine of mammals. In birds and reptiles, uric acid acts as a substance that removes excess nitrogen from the body (similar to urea in mammals). Guano (dried excrement of seabirds) contains up to 25% uric acid and is the source of its production.

Uric acid is characterized by lactam-lactam tautomerism ... In the crystalline state, uric acid is in the lactate (oxo) form, and in a solution between the lactam and lactam forms, a dynamic equilibrium is established, in which the lactate form predominates.

Uric acid is a diacid and forms salts - urata - respectively with one or two equivalents of alkali (dihydro- and hydrourates).

Alkali metal dihydrogen urate and ammonium hydrourate insoluble in water ... In some diseases, such as gout and urolithiasis, insoluble urates, along with uric acid, are deposited in the joints and urinary tract.

Oxidation of uric acid, as well as xanthine and its derivatives, forms the basis of a qualitative method for the determination of these compounds, called murexid test (qualitative reaction) .

Under the action of oxidants such as nitric acid, hydrogen peroxide or bromic water, the imidazole cycle is opened and pyrimidine derivatives are initially formed alloxan and dialuric acid ... These compounds are further transformed into a kind of hemiacetal - alloxanthin , when processed with ammonia, dark red crystals of murexide - ammonium salt of purpuric acid (in its enol form).

    Condensed heterocycles: purine - structure, aromaticity; purine derivatives - adenine, guanine, their tautomerism (question 22).

Adenine and Guanine... These two amino derivatives of purine, shown below as the 9H tautomers, are components of nucleic acids.

Adenine is also part of a number of coenzymes and natural antibiotics. Both compounds are found in free form in plant and animal tissues. Guanine, for example, is found in fish scales (from which it is isolated) and gives it its characteristic shine.

Adenine and guanine have weak acidic and weak basic properties. Both form salts with acids and bases; picrates are convenient for identification and gravimetric analysis.

Structural analogs of adenine and guanine, acting on the principle of antimetabolites of these nucleic bases, are known to inhibit the growth of tumor cells. Of the dozens of compounds that proved to be effective in experiments on animals, some are also used in domestic clinical practice, for example, mercaptopurine and thioguanine (2-amino-6-mercaptopurine). Other purine-based drugs include the immunosuppressant drug azathioprine and the antiherpes drug acyclovir (also known as zovirax).

    Nucleosides: structure, classification, nomenclature; relation to hydrolysis.

The most important heterocyclic bases are pyrimidine and purine derivatives, which are commonly called nucleic bases in nucleic acid chemistry.

Nucleic bases... For nucleic bases, abbreviations are adopted, composed of the first three letters of their Latin names.

The most important nucleic bases include hydroxy and amino derivatives of pyrimidine - uracil, thymine, cytosine and purine - adenine and guanine... Nucleic acids differ in their constituent heterocyclic bases. So, uracil is included only in RNA, and thymine - only in DNA.

Aromaticity of heterocycles in the structure of nucleic bases underlies their relatively high thermodynamic stability. In substituted pyrimidine cycle in the lactam forms of nucleic bases, the six-electron π-cloud is formed by 2 p-electrons of the double bond C = C and 4 electrons of two lone pairs of nitrogen atoms. In the cytosine molecule, an aromatic sextet arises with the participation of 4 electrons of two π-bonds (C = C and C = N) and a lone pair of electrons of pyrrole nitrogen. The delocalization of the π-electron cloud throughout the heterocycle is carried out with the participation of the sp 2 -hybridized carbon atom of the carbonyl group (one in cytosine, guanine and two in uracil, thymine). In the carbonyl group, due to the strong polarization of the π-bond C = Оp, the orbital of the carbon atom becomes, as it were, vacant and, therefore, capable of taking part in the delocalization of the lone pair of electrons of the neighboring amide nitrogen atom. Below, using the resonance structures of uracil, the delocalization of p-electrons is shown (using the example of one lactam fragment):

Nucleoside structure... Nucleic bases form with D-ribose or 2-deoxy-D-ribose N-glycosides, which in nucleic acid chemistry are called nucleosides and specifically, ribonucleosides or deoxyribonucleosides, respectively.

D-ribose and 2-deoxy-D-ribose are found in natural nucleosides in furanose form , i.e., in the form of β-D-ribofuranose or 2-deoxy-β-D-ribofuranose residues. In nucleoside formulas, carbon atoms in furanose rings are numbered with a prime number. N -Glycosidic bond is carried out between the anomeric C-1 "atom of ribose (or deoxyribose) and the N-1 atom of the pyrimidine or N-9 purine base.

(! ) Natural nucleosides are always β-anomers .

Building titles nucleosides are illustrated by the following examples:

However, the most common are names derived from trivial the names of the corresponding heterocyclic base with the suffix - idin in pyrimidines (for example, uridine) and - ozin in purine (guanosine) nucleosides. The abbreviated names of nucleosides are a one-letter code where the initial letter of the Latin name of the nucleoside is used (with the addition of the Latin letter d in the case of deoxynucleosides):

Adenine + Ribose → Adenosine (A)

Adenine + Deoxyribose → Deoxyadenosine (dA)

Cytosine + Ribose → Cytidine (C)

Cytosine + Deoxyribose → Deoxycytidine (dC)

An exception to this rule is the name “ thymidine "(And not" deoxythymidine "), which is used for deoxyribozide thymine, which is part of DNA. If thymine is linked to ribose, then the corresponding nucleoside is called ribothymidine.

As N-glycosides, nucleosides relatively resistant to alkali , but easily hydrolyzed when heated in the presence of acids ... Pyrimidine nucleosides are more resistant to hydrolysis than purine ones.

The existing "small" difference in the structure or configuration of one carbon atom (for example, C-2 ") in the carbohydrate residue is sufficient for the substance to act as an inhibitor of DNA biosynthesis. This principle is used to create new drugs by the method of molecular modification of natural models.

    Nucleotides: structure, nomenclature, relation to hydrolysis.

Nucleotides are formed as a result of partial hydrolysis of nucleic acids, or by synthesis. They are found in significant quantities in all cells. Nucleotides are phosphates of nucleosides .

Depending on the nature of the carbohydrate residue, a distinction is made between deoxyribonucleotides and ribonucleotides ... Phosphoric acid usually esterifies alcoholic hydroxyl when S-5 " or at S-Z " in the residues of deoxyribose (deoxyribonucleotides) or ribose (ribonucleotides). In a nucleotide molecule, three structural components are used to bind ester link and N -glycosidic bond .

The principle of structure mononucleotides

Nucleotides can be thought of as nucleoside phosphates (phosphoric acid esters) and how acid (due to the presence of protons in the phosphoric acid residue). Due to the phosphate residue, nucleotides exhibit the properties of a diacid and under physiological conditions at pH ~ 7 are in a fully ionized state.

Two kinds of names are used for nucleotides. One of them includes Name nucleoside indicating the position of the phosphate residue therein, for example adenosine-3 "-phosphate, uridine-5" -phosphate. Another kind of names is built by adding a combination - silt acid to the name of the nucleic acid residue, for example 3 "-adenylic acid, 5" -uridylic acid.

In nucleotide chemistry, the use of abbreviated names ... Free mononucleotides, that is, those that are not part of the polynucleotide chain, are called monophosphates with the reflection of this feature in the abbreviated code by the letter "M". For example, adenosine-5 "-phosphate has the abbreviated name AMP (in Russian literature - AMP, adenosine monophosphate), etc.

To record the sequence of nucleotide residues in the composition of polynucleotide chains, a different type of abbreviation is used using the one-letter code for the corresponding nucleoside fragment. In this case, 5 "-phosphates are written with the addition latin letter"P" before the one-letter nucleoside symbol, 3 "-phosphates after the one-letter nucleoside symbol. For example, adenosine-5" -phosphate - pA, adenosine-3 "-phosphate - Ap, etc.

Nucleotides are capable hydrolyze in the presence of strong inorganic acids (HC1, HBr, H 2 SO 4) and some organic acids (CC1 3 COOH, HCOOH, CH 3 COOH) on the N-glycosidic bond, the phosphate bond exhibits relative stability. At the same time, under the action of the 5'-nucleotidase enzyme, the ester bond is hydrolyzed, while the N-glycosidic bond is retained.

    Nucleotide coenzymes: ATP-structure, relation to hydrolysis.

Nucleotides are of great importance not only as monomeric units of polynucleotide chains of various types of nucleic acids. In living organisms, nucleotides are participants in the most important biochemical processes. They are especially important in the role coenzymes , i.e., substances closely related to enzymes and necessary for the manifestation of their enzymatic activity. All tissues of the body contain mono-, di- and triphosphates of nucleosides in a free state.

Especially famous adenine-containing nucleotides :

Adenosine-5 "-phosphate (AMP, or AMP in Russian literature);

Adenosine-5 "-diphosphate (ADP, or ADP);

Adenosine-5 "-triphosphate (ATP, or ATP).

Nucleotides phosphorylated to varying degrees are capable of interconversion by building up or cleaving phosphate groups. The diphosphate group contains one, and the triphosphate group contains two anhydride bonds, which have a large supply of energy and therefore called macroergic ... With the breakdown of macroergic communication R-O-32 kJ / mol is released. Associated with this is the most important role of ATP as a "supplier" of energy in all living cells.

Interconversion phosphates of adenosine.

In the above scheme of interconversions, the formulas AMP, ADP, and ATP correspond to the non-ionized state of the molecules of these compounds. With the participation of ATP and ADP in the body, the most important biochemical process is carried out - the transfer of phosphate groups.

    Nucleotide coenzymes: NAD + and NADF + - structure, alkylpyridinium ion and its interaction with hydride ion as a chemical basis for oxidative action, NAD + .

Nicotinamide adenine dinucleotides... This group of compounds includes nicotinamide adenine dinucleotide (NAD, or NAD) and its phosphate (NADP, or NADP). These compounds play an important role coenzymes in the reactions of biological oxidation of organic substrates by their dehydrogenation (with the participation of dehydrogenase enzymes). Since these coenzymes are participants in redox reactions, they can exist in both oxidized (NAD +, NADP +) and reduced (NADH, NADPH) forms.


The structural fragment of NAD + and NADP + is nicotinamide residue as pyridinium ion ... In the composition of NADH and NADPH, this fragment is converted into a substituted 1,4-dihydropyridine residue.

During biological dehydrogenation, which is special occasion oxidation, the substrate loses two hydrogen atoms, i.e., two protons and two electrons (2H +, 2e) or a proton and a hydride ion (H + and H). Coenzyme NAD + is considered as a hydride ion acceptor ... As a result of the reduction due to the addition of the hydride ion, the pyridinium ring is transformed into the 1,4-dihydropyridine fragment. This process is reversible.

During oxidation, the aromatic pyridinium ring transforms into the non-aromatic 1,4-dihydropyridine ring. Due to the loss of aromaticity, the energy of NADH increases compared to NAD +. The increase in energy content occurs due to part of the energy released as a result of the conversion of alcohol into aldehyde. Thus, NADH stores energy, which is then consumed in other biochemical processes that require energy consumption.

    Nucleic acids: RNA and DNA, primary structure.

Nucleic acids occupy an exclusive place in the vital processes of living organisms. They store and transfer genetic information and are a tool with which the biosynthesis of proteins is controlled.

Nucleic acids are high molecular weight compounds (biopolymers) built from monomeric units - nucleotides, in connection with which nucleic acids are also called polynucleotides.

Structure each nucleotide includes carbohydrate, heterocyclic base and phosphoric acid residues. The carbohydrate components of nucleotides are pentoses: D-ribose and 2-deoxy-D-ribose.

On this basis, nucleic acids are divided into two groups:

ribonucleic acids (RNA) containing ribose;

deoxyribonucleic acids (DNA) containing deoxyribose.

Matrix (mRNA);

Ribosomal (rRNA);

Transport (tRNA).

Primary structure of nucleic acids. DNA and RNA have common features v structure macromolecules :

The framework of their polynucleotide chains consists of alternating pentose and phosphate residues;

Each phosphate group forms two ester bonds: with the C-Z atom of the "previous nucleotide unit and with the C-5 atom" of the next nucleotide unit;

Nucleic bases form an N-glycosidic bond with pentose residues.

The structure of an arbitrary section of the DNA chain, selected as a model with the inclusion of four basic nucleic bases - guanine (G), cytosine (C), adenine (A), thymine (T), is given. The principle of constructing the polynucleotide chain of RNA is the same as that of DNA, but with two differences: the pentose residue in RNA is D-ribofuranose, and the set of nucleic bases does not use thymine (as in DNA), but uracil.

(!) One end of the polynucleotide chain, on which there is a nucleotide with a free 5 "-OH group, is called 5 "-end ... The other end of the chain, on which there is a nucleotide with a free 3 "-OH group, is called Z "-end .

Nucleotide units are written from left to right, starting from the 5 "-terminal nucleotide. The RNA chain structure is recorded according to the same rules, with the letter" d "omitted.

In order to establish the nucleotide composition of nucleic acids, their hydrolysis is carried out, followed by identification of the obtained products. DNA and RNA behave differently under conditions of alkaline and acidic hydrolysis. DNA resistant to hydrolysis in an alkaline environment , while RNA is hydrolyzed very quickly to nucleotides, which, in turn, are capable of cleaving off the phosphoric acid residue to form nucleosides. N -Glycosidic bonds are stable in alkaline and neutral environments ... Therefore, to split them acid hydrolysis is used ... Optimal results are obtained by enzymatic hydrolysis using nucleases, including snake venom phosphodiesterase, which cleave ester bonds.

As well as nucleotide composition the most important characteristic of nucleic acids is nucleotide sequence , i.e., the order of alternation of nucleotide units. Both of these characteristics are included in the concept of the primary structure of nucleic acids.

Primary structure nucleic acids are defined by the sequence of nucleotide units linked by phosphodiester bonds to form a continuous chain of a polynucleotide.

The general approach to establishing the sequence of nucleotide units is to use the block method. First, the polynucleotide chain is directionally cleaved with the help of enzymes and chemical reagents into smaller fragments (oligonucleotides), which are decoded by specific methods and, according to the data obtained, reproduce the sequence of the structure of the entire polynucleotide chain.

Knowledge of the primary structure of nucleic acids is necessary to identify the relationship between their structure and biological function, as well as to understand the mechanism of their biological action.

Complementarity bases underlies the laws governing the nucleotide composition of DNA. These patterns are formulated E. Chargaff :

The number of purine bases is equal to the number of pyrimidine bases;

The amount of adenine is equal to the amount of thymine, and the amount of guanine is equal to the amount of cytosine;

The number of bases containing an amino group at positions 4 of the pyrimidine and 6 of the purine nuclei is equal to the number of bases containing an oxo group at the same positions. This means that the sum of adenine and cytosine is equal to the sum of guanine and thymine.

For RNA, these rules are either not met, or are met with some approximation, since RNA contains many minor bases.

The complementarity of chains is the chemical basis of the most important function of DNA - storage and transmission of hereditary traits. The preservation of the nucleotide sequence is the key to the error-free transmission of genetic information. A change in the sequence of bases in any DNA chain leads to stable hereditary changes, and therefore to changes in the structure of the encoded protein. Such changes are called mutations ... Mutations can occur as a result of the replacement of any complementary base pair with another. The reason for this replacement may be a shift in the tautomeric equilibrium.

For example, in the case of guanine, a shift in the equilibrium towards the lactimal form makes it possible to form hydrogen bonds with a base unusual for guanine - thymine and the emergence of a new guanine-thymine pair instead of the traditional guanine-cytosine pair.

The substitution of "normal" base pairs is then transmitted during the "rewriting" (transcription) of the genetic code from DNA to RNA and ultimately leads to a change in the amino acid sequence in the synthesized protein.

    Alkaloids: chemical classification; basic properties, salt formation. Representatives: quinine, nicotine, atropine.

Alkaloids represent a large group of natural nitrogen-containing compounds, predominantly of plant origin. Natural alkaloids serve as models for the creation of new drugs, often more effective and at the same time simpler in structure.

Currently, depending on the origin of the nitrogen atom in the structure of the molecule, among alkaloids there are:

    True alkaloids - compounds that are formed from amino acids and contain a nitrogen atom in the heterocycle (hyoscyamine, caffeine, platifillin).

    Protoalkaloids – compounds that are formed from amino acids and contain an aliphatic nitrogen atom in the side chain (ephedrine, capsaicin).

    Pseudoalkaloids - nitrogen-containing compounds of terpene and steroid nature (solasodin).

V classification alkaloids, there are two approaches. Chemical classification based on the structure of the carbon-nitrogen skeleton:

    Derivatives of pyridine and piperidine (anabazine, nicotine).

    With fused pyrrolidine and piperidine rings (tropane derivatives) - atropine, cocaine, hyoscyamine, scopolamine.

    Quinoline derivatives (quinine).

    Isoquinoline derivatives (morphine, codeine, papaverine).

    Indole derivatives (strychnine, brucine, reserpine).

    Purine derivatives (caffeine, theobromine, theophylline).

    Imidazole derivatives (pilocarpine)

    Steroid alkaloids (solasonine).

    Acyclic alkaloids and alkaloids with an exocyclic nitrogen atom (ephedrine, spherofizin, colhamin).

Another type of classification of alkaloids is based on a botanical characteristic, according to which alkaloids are combined according to plant sources.

Most alkaloids has basic properties , which is the reason for their name. In plants, alkaloids are contained in the form of salts with organic acids (citric, malic, tartaric, oxalic).

Isolation from plant materials:

1st method (extraction in the form of salts):

2nd method (extraction in the form of bases):

Basic (alkaline) properties alkaloids are expressed to varying degrees. In nature, alkaloids are more common, which are tertiary, less often - to secondary or quaternary ammonium bases.

Due to their basic nature, alkaloids form salts with acids of varying degrees of strength. Alkaloid salts easily decomposed by caustic alkalis and ammonia ... In this case, free bases are allocated.

Due to their basic nature, alkaloids when interacting with acids form salts ... This property is used in the isolation and purification of alkaloids, their quantitative determination and preparation of drugs.

Alkaloids-salts OK soluble in water and ethanol (especially diluted) when heated, poorly or completely insoluble in organic solvents (chloroform, ethyl ether, etc.). As exceptions include scopolamine hydrobromide, cocaine hydrochlorides and some opium alkaloids.

Base alkaloids usually do not dissolve in water , but easily dissolve in organic solvents. Exception make up nicotine, ephedrine, anabasine, caffeine, which dissolve well both in water and in organic solvents.

Representatives.

Quinine - an alkaloid isolated from the bark of the cinchona tree ( Cinchona oficinalis) - represents colorless crystals of very bitter taste. Quinine and its derivatives have antipyretic and antimalarial effects

Nicotine - the main alkaloid of tobacco and makhorka. Nicotine is very toxic, the lethal dose for humans is 40 mg / kg, and natural levorotatory nicotine is 2-3 times more toxic than synthetic dextrorotatory.

Atropine - racemic form of hyoscyamine , has an anticholinergic effect (antispasmodic and mydriatic).

    Alkaloids: methylated xanthines (caffeine, theophylline, theobromine); acid-base properties; their qualitative reactions.

Purine alkaloids should be considered as N-methylated xanthines - based on the xanthine core (2,6-dihydroxopurine). The most famous representatives of this group are caffeine (1,3,7-trimethylxanthine), theobromine (3,7-dimethylxanthine) and theophylline (1,3-dimethylxanthine), which are found in coffee beans and tea, cocoa husks, and cola nuts. Caffeine, theobromine, and theophylline are widely used in medicine. Caffeine is used primarily as a psychostimulant, theobromine and theophylline as cardiovascular agents.

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