The Roténone is a organic Molécule, naturally produced by certain tropical plants, which is toxic for many species of animals with cold blood.
Etymology
The name " roténone" comes from the name Japanese of the plant Derris elliptica ( Roten ), it was given by the Chimiste Nagai Nagayoshi which insulated this Molécule with the Japan in 1902.
Chemistry
The roténone was insulated in several plant species which all push on poor grounds, generally acid and in the presence of a wet atmosphere (75% of moisture minimum):- Derris elliptica ( Barbasco in Spain, Cubed with the Brazil, Intchipari in Amazonia, Roten with the Japan),
- Lonchocarpus nico U (liana), Geoffray extracted the same substance as of 1895 and gave the name of Nicouline (Mc Ewen & Stephenson 1976)
- Téphrosia vogelii , but there are 64 different in the family of Fabaceae.
Composition
Aspect
Crystalline white powder.
Solvent
The roténone is soluble in the Acétone, the Trichloréthylène, the Chloroforme, some Solvant S organics but not in water in its purified form.
History
Plants rich in roténone were thus used and are it still for the Nivrée S (or fishes with nivrée) in Malaysia, equatorial Africa and Amazonia for their virtues “ichtyotoxic” (which kills fish).Their use could date of more than 2000 years. With the the Middle Ages, Europeans imported via Venice, Genoa, Barcelona or Marseilles l'" Persanne" bleaches on grass; of Indonesia or Malaysia while passing by the the Middle East. As of the years 1920, one made of it a powder Insecticide (produced at a rate of thousands of tons per annum starting from crop plants with Brazil, Peru, Belgian Congo, in French equatorial Africa, with the Kampuchea and in Indonesia Dutchwoman. The most important importers were Dutch and Belgian before the USA and France). As from the years 1945, DDT or HCH then other insecticidal molecules replaced the roténone. Then for environmental reasons (biodeterioration), she is again appreciated.
Discusses on human toxicity and the Parkinson's disease
The administration by chronic injection with low dose repeated of roténone causes in the rats the Parkinson's disease. With the difference of the Neurotoxic majority of the substances S, the roténone has a selective toxicity for the producing neurons of Dopamine. Its toxicity would come from its inhibiting effect of complex I of the respiratory chain mitochondriale. It is thus particularly used to include/understand the mechanisms of the Parkinson's disease. In its initial phase, the neurotoxicity of the roténone does not involve any symptom. When the primary symptoms appear, the damage is already irremediable.The unceasingly increasing and standardized use roténone coincides with the increase in case of Parkinson's disease. Other insecticides (of synthesis those there) are also shown finger.
The legal statute of the roténone in France does not take account of this discussed knowledge. Indeed, the normal exposure of the users can be done only by inhalation or ingestion. In these cases there, the roténone is neutralized by the alkalinity of the Intestin, it is not transmitted to blood circulation and thus cannot arrive at the Cerveau.
The results of a chronic experiment of administration of roténone by ingestion showed that there was no development of symptoms of Parkinson. However this study on 320 rats lasted 12 months and the amounts of roténone were 30 times higher (75 Mg per kg).
In the experiment of the University of Emory, the roténone was mixed with products which are not used in agriculture and which have the property to support the penetration of the molecules through fabrics.
The object of the study was not to accuse the agricultural use of the roténone in the development of the Parkinson's disease. The author specifies itself besides that the roténone has a low toxicity when it is managed by oral way.
The goal of the researcher was simply to find a means systematically of obtaining rats reached of the disease for better being able to study the lesions than it causes in fabrics of the brain.
How to protect itself?
For the farmer
Initially to set up a culture which decreases the need for treatment:Rather than to force the ecosystem, it is more advantageous to direct it to support natural resistance to the Ravageur S. That passes initially by the rustic choice of Semence S, selected by generations of farmers who did not have treatments, then by the judicious association of the species and finally by supporting the development of predatory ravageurs (for example the ladybird S).
In the event of treatment, it is necessary to respect the same precautions as for the use of a chemical insecticide (gloves, mask, combination etc) and to let spend a few days before harvest to make it possible the sun to degrade the roténone.
For the consumer
The roténone being sensitive to the light, the exposure in full sun of the fruit and vegetables during one day before consumption makes it possible to destroy most of the roténone on the external surface of the plant. Attention however with the parts of the plants in the shade, either because they present folds like the Chou X for example, or which they have a surface in the shade.Although the roténone is nonwater soluble, a meticulous washing with friction makes it possible to eliminate a little more the residues.
The use of roténone in the dwellings (insecticidal, Acaricide S) is to be proscribed absolutely.
Ecotoxicity
- Its activity on the insects seems related to the blocking of ATP by the inactivation of the cytochrome-B.
- the Mitochondrie is thus deprived of the energy which its oxygen conveyer brings to him normally: the ATP.
- the molecule being unstable in the water and exposed to the light, it degrades and loses its toxicity with time, more or less quickly according to the environment.
- It seems that in the case of the fish, the roténone acts as of the contact with the Branchie S. It would not penetrate the flesh, which can thus be consumed, the more so as cooking degrades the molecule. Ritually, the Indians Wayana should not drink another drink only reserved water on which fleet of the Roseau X during the operation of the Nivrée. Is the direction given to this act only symbolic system (it would be a question by a magic relation of making so that like the reed which floats, the asphyxiated fish also go up and float), or the tradition it also indicates that one should not drink the water poisoned by the juice of the lianas used to kill fish?
- the Mitochondrie is thus deprived of the energy which its oxygen conveyer brings to him normally: the ATP.
See too
References
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