Alkaloids are organic compounds that can affect animal and human organisms. Most alkaloids are produced by plants.
What are alkaloids?
The term alkaloids comes from Arabic and means plant ash. Alkaloids are naturally occurring organic compounds produced in the secondary metabolism of plants, bacteria, and fungi. These secondary metabolites, unlike 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. At that time, he was concerned with alkali-like plant substances such as strychnine, morphine and solanine. A precise definition of the term alkaloids still does not exist today. However, all alkaloids have in common that they affect the animal and human organism. Typical are also the bitter taste and the mostly toxic effect. Alkaloids can be subdivided according to various aspects. Usually, the categorization is based on origin, biogenesis, pharmacological action and chemical structure. Thus, in terms of chemical structure, alkaloids with heterocyclic nitrogen can be distinguished from alkaloids with acyclic nitrogen. For example, the pyrrolidine alkaloids, the piperidine alkaloids, and the indole alkaloids belong to the first group. Alkaloids with acyclic nitrogen are, for example, ephedrine and mescaline. In terms of origin, curare alkaloids, ergot alkaloids, opiates and vinca alkaloids can be distinguished. In addition, a classification can be made according to the pharmacological effect.
Function, action and tasks
The alkaloids represent an important group of active substances for medicine. For example, the alkaloids from ergot are used for the therapy of low blood pressure, fainting spells and cardiovascular complaints. The active ingredient dihydroergotoxin is used to treat high blood pressure. This is also an alkaloid obtained from ergot. In the therapy of headaches and migraines, the active ingredient ergotamine plays a decisive role. Ergotamine, like bromocriptine, is also an alkaloid. Bromocripton is used in the therapy of Parkinson’s disease. Another area of application for bromocripton is acromegaly. Here, due to a hormonal disorder, there is an enlargement of the ears, nose, hands and feet. Ergot alkaloids also affect the muscles of the uterus. The active ingredient methylergometrine, which is extracted from ergot, causes the uterus to contract. It is therefore given to women after delivery in whom the uterus does not contract. Opiates are also used medicinally. Opiates are the natural substances found in opium. The main opiates are morphine, codeine, thebaine, noscapine, papaverine, and narceine. Morphine is used to treat severe acute and chronic pain. The alkaloid is also used for symptomatic therapy of anxiety, cough and shortness of breath. Codeine is an alkaloid used for cough suppression. Papaverine affects vascular tension in the cardiovascular system. It is used, among other things, in the treatment of cerebral and peripheral circulatory disorders. The alkaloid is also used in the therapy of erectile dysfunction.
Formation, occurrence, properties, and optimal values
Alkaloids can be obtained from various plants. For example, there are the 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 the ergot fungus. This fungus attacks food and feed grains. Rye is particularly frequently affected. Opiates come from the opium poppy. The alkaloids are extracted from the milky sap 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 from the dog poison genus. These include various periwinkle species. The pharmaceutical parent plant is the lesser periwinkle (Vinca minor). Various semi-synthetic derivatives are produced from vincamine.
Diseases and disorders
Alkaloids are toxic, so poisoning can occur if the wrong dosage is used or accidentally consumed. Common symptoms of poisoning include redness of the skin, blistering, and necrosis formation. Those affected suffer from nausea, vomiting and diarrhea. Severe abdominal pain and colic are also possible. In addition, headaches, cramps and drowsiness develop. In the worst case, shortness of breath or even respiratory paralysis occurs. The toxic effects of ergot alkaloids include intestinal spasms and hallucinations. In addition, fingers and toes die due to circulatory disturbances. The clinical picture that results from ergot alkaloid poisoning is also called ergotism. The circulatory disorders also affect the kidneys and the heart muscle. The extremities of the affected persons are cold, pulses are hardly palpable. In addition, there are skin tingling, sensory disturbances, and paralysis. Acute poisoning can quickly lead to death due to cardiac arrest or respiratory failure. Chronic poisoning is more likely to lead to secondary infections with subsequent blood poisoning. Curare alkaloids are inhibitors of the neurotransmitter acetylcholine. Displacement of the neurotransmitter at the motor end plates results in paralysis of the muscles. In curare alkaloid poisoning, the respiratory muscles may also be affected. The result is fatal respiratory paralysis. Digitalis is an alkaloid used to treat heart failure. As with many alkaloids, the therapeutic window here is very narrow, and the boundaries between toxic and therapeutic effects are fluid. Digitalisine intoxication is associated with nausea and color vision. If the dose of the alkaloid is not adjusted, cardiac arrhythmias develop that can have a fatal outcome.
