L-Dioxyphenylalanine ( 3,4-dioxiphenylalanine , DOPA) is an amino acid , the product of tyrosine hydroxylation. An intermediate product of the biosynthesis of dopamine , norepinephrine , adrenaline and melanins , is used as a medicine of levodopa - an antiparkinsonian drug; with parkinsonism, the dopamine content in the basal ganglia of the brain is lowered; for the treatment of this disease, it is advisable to use substances that increase the dopamine content in the central nervous system . Dopamine cannot be used for this purpose, since it penetrates poorly through the blood-brain barrier . Dioxyphenylalanine (dopa), which is absorbed by oral administration, enters the central nervous system, decarboxylates , turns into dopamine and, replenishing its reserves in the basal ganglia, stimulates dopamine receptors and provides a therapeutic effect in Parkinson's disease.
| L-dioxiphenylalanine | |
|---|---|
 | |
| General | |
| Systematic name | (S) -3,4-dihydroxyphenylalanine |
| Traditional names | L-dioxiphenylalanine, L-DOPA, levodopa |
| Chem. formula | C 9 H 11 O 4 N |
| Rat formula | C 6 H 3 (OH) 2 CH 2 CH (NH 2 ) COOH |
| Physical properties | |
| Molar mass | 197.19 g / mol |
| Chemical properties | |
| Solubility in water | slightly soluble |
| Solubility in ethanol | not soluble |
| Classification | |
| Reg. CAS number | 59-92-7 |
| Reg. EINECS number | 200-445-2 |
As a drug of levodopa, a synthetic levorotatory isomer of dioxiphenylalanine - L-dopa, which is much more active than the dextrorotatory isomer, which eliminates hypokinesia , rigidity , tremor , dysphagia, is used . Dopamine formed in peripheral tissues is not involved in the implementation here, but is responsible for most of its side effects. The therapeutic effect is observed after 6-8 days, and the maximum - after 25-30 days. It is established that the therapeutic effect is achieved in 50-60% of patients.
In others, the effect is not very pronounced, the dosage cannot be increased due to side effects.
Treatment begins with small doses, by mouth, gradually increasing them to the optimum for everyone.
The initial dose is 0.25-1 g in 2-3 doses. The dose is gradually increased by 0.125-0.75 g every 2-3 days, depending on tolerance and until the optimal therapeutic effect is achieved. The maximum daily dose is 8 g. Cancellation is carried out gradually.
Content
- 1 side effects
- 1.1 From the digestive system
- 1.2 From the nervous system
- 1.3 from the cardiovascular system
- 1.4 From the hemopoietic organs
- 1.5 Others [edit | edit code]
- 2 Getting
- 3 Physical properties
- 4 Biological role
- 5 Application
- 6 notes
- 7 Literature
Side Effects
From the digestive system
Decreased appetite , nausea , vomiting , constipation , dysphagia , ulceration of the mucous membrane of the gastrointestinal tract , gastralgia , gastrointestinal bleeding (in patients with a history of peptic ulcer ).
From the nervous system
Drowsiness or insomnia , anxiety, dizziness , paranoid conditions, hypomania (with increased sexual desire and antisocial behavior), euphoria , depression , dementia , ataxia , convulsions , spasmodic torticollis , dyskinesia , choreiform, dystonic and other uncontrolled thoughts, suicidal movements.
From the cardiovascular system
Decreased blood pressure , orthostatic collapse , arrhythmias , tachycardia .
From the hemopoietic organs
Leukopenia , thrombocytopenia .
Others [edit | edit code]
Polyuria rarely - diplopia .
Getting
- Hydroxylation [1] - this is oxidation under the influence of enzymes ; in which the conversion of many foreign compounds into their metabolites containing hydroxyl groups occurs. Therefore, such oxidation reactions are called hydroxylation reactions. Upon oxidation, tyrosine rings (under the action of the tyrosinase enzyme ) hydroxylate the essential amino acid phenylalanine to tyrosine. Tyrosine biosynthesis is considered in more detail in the article shikimatny path . Tyrosine is classified as an amino acid that is replaceable for most animals and humans, since in the body this amino acid is formed from another ( irreplaceable ) amino acid - phenylalanine .
Physical Properties
- White crystalline powder, slightly soluble in water, insoluble in alcohol .
- It has optical isomerism and the biologically active L-isomer.
Biological role
Dopamine is commonly known as the "pleasure hormone." When we experience positive emotions, its level rises. And the brighter and sharper our sensations, the more dopamine we get. This is the basis of the human motivation system - biochemistry in its purest form: all the great feats and achievements are always an attempt by the body to get some more dopamine. Over time, other functions of this substance were discovered and studied.
If we summarize all the information not known to date about the effect of dopamine, then the groups of its functions can be described as follows:
- Responsibility for reward and motivation reactions. When significant results are achieved for a particular person, there is an increase in the release of dopamine into the blood, and we experience positive emotions. Conversely, with a negative result, the brain, through a decrease in the content and release of dopamine, introduces us into a state of displeasure. The hormone serves to form a reinforcement reaction in case of success, thanks to this, motivation is acquired for further work.
- Behavior control. The hormone is responsible for converting instinctively arising impulses to action into concrete steps to achieve the goal. In other words, it regulates the fulfillment of our desires, including sexual ones. Dopamine helps us make choices in strategies for behavior in a particular situation. The same system is responsible for the formation of pathological dependence, for example, addiction.
- Control of motor functions. In clinical practice, it has been established that the gradual death of neurons in a given signal chain leads to the development of Parkinson's disease.
- Regulation of the level of other hormones in the body, in particular, inhibition of prolactin synthesis.
- Impact on cognitive abilities. Dopamine improves concentration, increases focus and memory, while also making it easier to switch attention while thinking about decisions.
Thus, the functions of dopamine in the body are very diverse. This is one of the most important hormones, and a neurotransmitter that improves mood and arouses interest in life. Therefore, the study of the hormone precursor, the L-DOPA substance for medical purposes, presents a great potential.
Application
Larodopa [2] is an antiparkinsonian drug.
Notes
- ↑ XuMuK.ru - § 10. OXIDATION OF ALIEN COMPOUNDS. Toxicological chemistry. V.F. Kramarenko . www.xumuk.ru. Date of treatment November 15, 2018.
- ↑ Larodopa - Instructions for use . www.etolen.com. Date of treatment November 15, 2018.
Literature
- Matlina E. Sh., Menshikov VV, Clinical biochemistry of catecholamines, M., 1967;
- Grollman A., Clinical endocrinology and its physiological basis, trans. from English., M., 1969.
- Surfing Articles on the Internet, 2018