What are alkaloids?
The term alkaloids comes from the Arabic and means plant ash. The alkaloids are naturally occurring organic compounds that are produced in the secondary metabolism of plants, bacteria and fungi.
These secondary metabolites, in contrast to the primary metabolites, are not necessary for the growth of the producers. The chemical compounds are mostly alkaline and nitrogenous. More than 10, 000 different substances are assigned to the substance group of alkaloids. The term alkaloids was coined in 1819 by the pharmacist Carl Friedrich Wilhelm Meißner. He then dealt with alkaline-like plant substances such as strychnine, morphine and solanine. A precise definition of the term alkaloids does not exist until today. However, all alkaloids have in common that they affect the animal and human organism. Typical are also the bitter taste and the most toxic effect.
Alkaloids can be subdivided according to different aspects. Usually, categorization is based on origin, biogenesis, pharmacological action and chemical structure. Thus, in the chemical structure, alkaloids with heterocyclic nitrogen can be distinguished from alkaloids with acyclic nitrogen.
The first group includes, for example, the pyrrolidine alkaloids, the piperidine alkaloids and the indole alkaloids. Alkaloids with acyclic nitrogen are, for example, ephedrine and mescaline. By origin, curare alkaloids, ergot alkaloids, opiates and vinca alkaloids can be distinguished. In addition, a classification according to the pharmacological effect can be made.
Function, effect & tasks
The alkaloids represent an important group of active ingredients for medicine. For example, the alkaloids from ergot are used for the treatment of low blood pressure, in fainting and in cardiovascular disorders.
For the treatment of hypertension, the active ingredient dihydroergotoxin is used. Again, this is an alkaloid that is extracted from the ergot. In the treatment of headache and migraine, the active ingredient ergotamine plays a crucial role. Ergotamine, like bromocriptine, is also an alkaloid. Bromocriptone is used in the treatment of Parkinson's disease. Another application for bromocriptone is acromegaly.
Due to a hormonal disorder, there is an enlargement of the ears, nose, hands and feet. Ergot alkaloids also affect the musculature of the uterus. The active substance methylergometrine, which is extracted from the ergot, leads to a contraction of the uterus. He is therefore given post-partum women who do not contract the uterus.
Opiates are also used medically. Opiates are the natural substances found in opium. The most important opiates are morphine, codeine, thebaine, noscapine, papaverine and narcein. Morphine is used to treat severe acute and chronic pain. The alkaloid is also used for the symptomatic treatment of anxiety, cough and respiratory distress. Codeine is an alkaloid used for the treatment of coughing. Papaverine affects vascular tension in the cardiovascular system. It is used inter alia for the treatment of cerebral and peripheral circulatory disorders. The alkaloid is also used in the treatment of erectile dysfunction.
Education, occurrence, properties & optimal values
Alkaloids can be obtained from different plants. For example, there are curare alkaloids. They are obtained from thickened extracts of barks and leaves of South American Liana species. The ergot alkaloids are derived from the ergot. Ergot is a permanent form of ergot fungus.
This fungus infests food and feed crops. Rye is particularly common. Opiates are derived from opium poppy. The alkaloids are extracted from the latex of the plant. However, there are also synthetic opiates such as heroin or pethidine. Vinca alkaloids, which are used in chemotherapy, are found in plants of the genus Hundsgiftgewächse. These include various evergreen species. The pharmaceutical parent plant is the small periwinkle (Vinca minor). From vincamine various semi-synthetic derivatives are produced.
Diseases & Disorders
Alkaloids are poisonous, which can lead to poisoning if used incorrectly or accidentally. Common signs of intoxication include redness of the skin, blistering and necrosis. Those affected suffer from nausea, vomiting and diarrhea. Also severe abdominal pain and colic are possible. In addition, headaches, cramps and dizziness develop. In the worst case it comes to breathlessness up to respiratory paralysis.
The toxic effects of the ergot alkaloids include intestinal spasms and hallucinations. In addition, the fingers and toes die due to circulatory disorders. The disease caused by poisoning with ergot alkaloids is also called ergotism. The circulatory disturbances also affect the kidneys and the heart muscle. The limbs of those affected are cold, pulses are barely palpable. In addition, there are skin tingling, sensory disorders and paralysis. Acute poisoning can quickly lead to death due to cardiac arrest or respiratory arrest. Chronic poisoning leads more to secondary infections with subsequent blood poisoning.
Curare alkaloids are inhibitors of the neurotransmitter acetylcholine. The displacement of the neurotransmitter at the motor end plates leads to a paralysis of the musculature. In case of poisoning with curare alkaloids, the respiratory muscles may also be affected by the effect. The result is a deadly respiratory paralysis.
Digitalis is an alkaloid used to treat heart failure. As with many alkaloids, the therapeutic window is very narrow here, the boundaries between toxic and therapeutic effects are fluid. Digitalis intoxication involves nausea and color vision. If the dose of the alkaloid is not adjusted, cardiac arrhythmias develop, which can be fatal.