Snake venom
Snake poisons ( snake toxins , also ophiotoxins ) are the physiologically active components of the venomous system of venomous snakes . They are mainly used for prey hunting and digestion, as well as for defense against attackers. There is no reliable information on the number of deaths caused by poisonous snakes worldwide every year; an estimate from May 2008 indicates 21,000 to 94,000 deaths per year.
composition
The systematic research and analysis of snake venom has been carried out since the 1960s. Of the approximately 3,200 known species of snakes, around 1,300 are poisonous snakes. The comprise Boiginae (deceit snakes) far the largest group, followed by the Elapidae (Venomari) , the Hydrophiinae (sea snakes) , the Viperidae (vipers) and the Crotalinae (pit vipers) .
From a biochemical point of view, the dry mass of snake venom consists of over 90% proteins and polypeptides , including larger enzymes with masses between 13 and 150 kDa , which intervene in the biological functions of the bite victims and block them, and mostly very small (<5 kDa), through disulfide bridges stabilized toxic peptides.
Venom components of all venomous snakes
Most snake poisons contain the following enzymes, which, with the exception of amino acid oxireductase , which catalyzes the oxidation of L-amino acids , belong to the group of hydrolases : adenosine triphosphatase , deoxyribonuclease II, hyaluronidase , NAD nucleosidase , 5′-nucleotidase , peptidase , Phosphodiesterase , phospholipase A2 , ribonuclease and acid phosphatase . In addition, one finds the metal ions Mg 2+ , Ca 2+ , Zn 2+ , (less often copper,) which can occur in relatively high concentrations of up to 0.5% and act as cofactors for the enzymes present. Furthermore - especially in the poisons of vipers and pit vipers - there are small peptides (<1.5 kDa) with a high proline and N-terminal pyroglutamine content, which act as enzyme inhibitors, and finally lipids , nucleosides , carbohydrates , Detect amines , serotonin and acetylcholine in smaller amounts.
Poison components in pit vipers and vipers
In pit vipers and vipers, arginine ester hydrolase , endopeptidases , factor X activator , kininogenases , prothrombin activator and thrombin-like protease (ancrod), which splits fibrinogen and thrombin and thus has an influence on blood coagulation, have been detected. Furthermore, small myotoxins (5-10 kDa) are characteristic of these venomous snakes .
Venom components in venomous snakes
The enzymes acetylcholinesterase , glycerol phosphatase and phospholipase B could be detected in venomous snakes . Toxic peptides (5–10 kDa) α- neurotoxins , cardiotoxins (in cobras ) and dendrotoxins (in mambas ) are found especially in this species .
Bungarotoxin
The so-called bungarotoxins ( alpha , beta , gamma and kappa ) are found in the kraits from the poisonous snake family, which are common in Southeast Asia . It's neurotoxins . The alpha-bungarotoxin irreversibly blocks the nicotinic acetylcholine receptors and thus paralyzes the muscles (non-depolarizing muscle relaxant ). In contrast, beta and gamma bungarotoxin presynaptically force the release of acetylcholine and thus act as a depolarizing muscle relaxant.
Poison components in sea snakes
Sea snake venom contains a large number of extremely toxic α- neurotoxins .
Rare poison components
The enzymes alanine aminotransferase , amylases , β-glucosaminidase and catalase have been found in the venom of some venomous snakes .
effect
The poisons of the different snakes or their components can be divided into different groups according to their chemical composition and their starting point or their effect in the organism: (the text written in italics describes direct symptoms in humans)
- Signs of inflammation
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Cytotoxicity : damage to cells and tissues
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Hemorrhage : damage to blood cells and vessels
- internal bleeding , circulatory shock , renal insufficiency
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Cytolysis : Damage to muscle, skin and connective tissue
- severe pain , necrosis , impaired vision
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Myotoxicity : damage to muscle tissue
- Muscle weakness
- Cardiotoxicity : damage to the heart cells
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Hemorrhage : damage to blood cells and vessels
- Neurotoxicity : effect on the nervous system
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Haemotoxicity , effect on blood clotting ( thrombocytes )
- Reduced blood clotting by reducing fibrinogen
- Thrombosis
- Poison allergy
These symptoms are often (but not necessarily) accompanied by general symptoms such as fever , nausea , headache , vomiting, and the like. The effect of the poison on the organism is formed not only by one, but often by many components. It is not only the composition of the proportions that is decisive, but also their relationship to one another. In many cases, several components with different effects (hemotoxic, neurotoxic etc.) are combined in one poison.
Toxicity and occurrence
The effect of poisons is generally assessed on the basis of the mean lethal dose (LD 50 value). Most of the world's most venomous snakes are native to Australia. As poisonous of all snakes in general which also applies in Australia occurring inland taipan , whose "taipoxin" in mice a LD 50 value of 2 micrograms / kg body weight for subcutaneous administration does.
Germany
In Germany there are only two venomous snakes in the wild: the aspic viper (up to 1 m long) and the adder (also up to 1 m long). The venom of the adder is relatively strong, but it only has a maximum of 18 mg of it. Therefore, a bite is rarely fatal for a healthy adult (for this he would have to be bitten by several snakes at once, which is extremely unlikely); However, caution should be exercised with children who weigh less than 30 kg or the elderly. A doctor should be consulted immediately after a bite, as infections from bacteria living in the snakes' mouths often occur.
Switzerland
The last death from a poisonous snake bite in Switzerland dates back to 1961. Since then there have been no fatal bites from adder or aspic viper.
Snake venom in medicine
Like many other poisons, snake venom can be used for medicinal purposes in small doses. In addition to direct use as a medicinal product , it can also contribute to the search for new drugs. It can help to clarify and better understand physiological processes and to find new active ingredients . Snake poisons served as a template for some antihypertensive drugs from the group of ACE inhibitors (captopril, enalapril). Snake poisons are used in the following areas of therapy:
- for arterial hypertension (high blood pressure), hereditary and acquired disorders of the coagulation system and for the production of antidotes (antidotes)
- in homeopathy for the treatment of painful conditions
- Some blood coagulation tests used by hematologists are based on snake venoms such as reptilase
It is obtained in snake farms by "milking" the poison glands. To do this, the teeth are put through a membrane over a container and the poison glands are massaged. The poison that runs off is frozen, freeze-dried and ground into granules.
See also
literature
- Hans-Ulrich Siebeneick: The biochemistry of snake poisons, chemistry in our time , 10th year 1976, No. 2, pp. 33–41, doi : 10.1002 / ciuz.19760100202 .
- Roland Bauchot (Ed.): Schlangen , Weltbild Verlag, 1994, ISBN 3-8289-1501-9 .
- Alan L. Harvey (Ed.): Snake Toxins , International Encyclopedia of Pharmacology and Therapeutics, Sect. 134, Pergamon Press, New York, Oxford, Beijing, Frankfurt, São Paulo, Sydney, Tokyo, Toronto, 1991.
Web links
- Snake venom in naturopathy ( Memento from February 6, 2005 in the Internet Archive )
- Mast cells break down snake venom
- LD50 values for snakes (english)
Individual evidence
- ↑ Anuradhani Kasturiratne, A. Rajitha Wickremasinghe, Nilanthi de Silva, N. Kithsiri Gunawardena, Arunasalam Pathmeswaran1, Ranjan Premaratna, Lorenzo Savioli, David G. Lalloo, H. Janaka de Silva: The Global Burden of Snakebite: A Literature Analysis and Modeling Based on Regional Estimates of Envenoming and Deaths. PLoS Medicine Vol. 5, No. 11, e218, November 4, 2008. doi : 10.1371 / journal.pmed.0050218 .
- ^ National Library of Medicine - Medical Subject Headings: Bungarotoxins ; here online , last viewed on Jan. 21, 2016.
- ↑ Science online lexica: Entry on "Taipoxin" in the lexicon of neuroscience. Retrieved June 8, 2010.
- ↑ J. Fohlman, D. Eaker, E. Karlsoon, S. Thesleff: Taipoxin, an extremely potent presynaptic neurotoxin from the venom of the australian snake taipan (Oxyuranus s. Scutellatus). Isolation, characterization, quaternary structure and pharmacological properties. Eur J Biochem 1976 Sep 15; 68 (2): 457-69.
- ↑ Swiss Federal Institute for Snow and Avalanche Research, Davos: Safety, Medicine, Rescue: Venomous snakes in the Swiss Alps (PDF). ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. Die Alpen, 8, 1999: pp. 25-29.
