The Molecular Forms of Cholinesterase - Term Paper Example

The Molecular Forms of Cholinesterase Abstract Malathion is a chemical compound that comes under few organophosphorous insecticides that had been developed and used during the 1950s[Bhu05]. This pesticide is very commonly used in agriculture, residential landscaping, public recreation areas, and public pest control programs, for instance mosquito eradication[Uni08]. Its usage is very common in the US. Besides this, Ovide Malathion is a lotion used for getting rid of head lice. It is a toxic substance and is used to kill the lice. The drug has been approved by the US Food and Drug Administration (FDA) who claims that the lotion is harmless and can be used for killing lice and their eggs. However, although it is used heavily it is very harmful and its consequences cannot be ignored at any cost. The compound, malathion, causes damage to the various parts of the body and thus it is important to consider the amount of malathion used and for the what purpose. Malathion (Ovide) Introduction Malathion is an organophosphate parasympathomimetic and following a chemical reaction it irreversibly binds with cholinesterase. Its International Union of Pure and Applied Chemistry (IUPAC) name is O,O-dimethyl dithiophosphate of diethyl mercaptosuccinate Malathion is the first member of the family of organophosphorous compounds and its insecticidal properties are quite a few while having low mammalian toxicity. However, through a study it was found that the children having high levels of organophosphate pesticide metabolites in their urine very often suffer from attention deficit hyperactivity disorder (ADHD)[Tho10]. The molecular formula for malathion is C10H19O6PS2 and its chemical structure, thus, becomes this: Too much malathion in a body is harmful. The muscarinic symptoms resulting from high malathion exposure is that the affected person perspires too much, his pupils constrict and lacrimation takes place. Salivation, cramps in the abdomen, diarrhea, nausea, vomiting, chest tightness and difficulty in breathing are among the other signs. Nicotinic symptoms that may arise are muscle weakness, cramped or twitched muscles, ataxia and paralysis. Content The synthesis of malathion involves a reaction of O,O-dimethylphosphorodithiotic acid with diethymaleate. The reaction takes in a single step. P4S10 is reacted with methanol resulting in the synthesis of O,O-dimethylphosphorodithiotic acid. This is then added to diethylmaleate and there is no such need to isolate it from the reaction mixture. The chemical equation that is formed of this reaction in words and formula is this: Malathion proves to be toxic if it comes in contact with skin, if it is ingested or inhaled[Tom06]. Malathion and other such organophosphate insecticides can be bound with the protein acteylcholinesterase (AChE) at nerve endings. AChE is an enzyme and malathion binds with it. This enzyme is found in mammals, amphibians, fish, reptiles and birds[Mas82]. Normally AChE binds with the neurotransmitter acetylcholine (ACh) at the nerve junction, and this makes its end the stimulation of the other neuron. In case AChE has a bonding with malathion’s metabolite malaxon, there is an accumulation of ACh at the nerve junction and as a result the nervous system, glandular cells, autonomic ganglia and smooth and skeletal muscles becomes overstimulated. Malathion, however, is not toxic till it has been bioactivated. The mediation for bioactivation is cytochrome P450 enzymes that can be found within the liver. This enzyme leads to the creation of the active metabolite malaoxon by means of oxidative sulfuration[Rob98]. All kinds of organophosphate pesticides, which obviously also includes malathion, seem to be sharing a common mode of action. One similarity is that their uptake and metabolism in insects and mammals is same. When these kinds of pesticides are exposed to multiple organophosphates they can become further toxic. Still, there is a variance among the different organophosphates regarding their potency and its absorption rate by the body, which actually depends upon the way it is being exposed to it. On the other hand, however, microorganisms such as bacteria make use of malathion to get carbon and phosphorous. And plants do not find malathion to be toxic. This is because they metabolize it to malaoxon, but this process is actually pretty minor and malaoxon is eliminated very quickly. The reason for malathion not being toxic to plants and such organisms is that it basically targets the nervous systems only. In case too much malathion enters the human body the situation can be identified through certain signs and symptoms. These, however, depend on the target enzyme and its sensitivity, the area where the synapse has been affected, the degree to which that synapse has been exposed to malaoxon and how malaoxon reached it. A human body may undergo fluctuations in the blood pressure and heart rate. The central nervous system’s cholinergic neurons may be affected which can result in headache, confusion, insomnia, breathing problems, convulsions and coma. Children have somewhat different signs as compared to the adults and these include lowered heart rate, perspiration, muscle tremors, and lacrimation than the adults. It is very much possible for the children to become lazy, have seizures, too much of salivation, weakness in muscles and even coma. Therefore, care has to be taken when using Ovide Malathion. Conclusion When malathion and related products are stored for long durations the result can be that the degradation products, which allow for the inhibition of liver enzymes having the responsibility to detoxicate malathion, are accumulated. Another way is through heat. When malathion is exposed to higher temperatures the isomalathion is formed and this compound is a potent AChE inhibitor. Carboexylesterase is a compound responsible for degrading malathion. This compound is found in mammals and birds and, in lesser quantities, in insects. Therefore, mammals and birds are able to carry out degradation of malathion at a much faster rate as the rate of oxidation to the malaoxon form. The detoxification and then excretion of malathion in mammals and birds takes place at a higher rate than in insects. Therefore, it is said to be less toxic to these organisms as compared to others. However, when insects are continuously being exposed to malathion their tolerance level against the toxin increases and they produce more carboxylesterase as compared to their normal partners. This is the reason for resistant insect pests. Because insects are not able to degrade malathion very quickly the Ovide Malathion proves to be a good treatment for getting rid of head lice. Thus, it is commonly used because of its effectiveness. However, malathion is a toxic substance and care has to be taken in order to prevent any mishaps or problems that may result due to over exposure to malathion. Malathion is a chemical compound and it is used widely throughout the world. It is so common that it is necessary to consider the consequences of the compound. As discussed earlier, there are so many harmful results and people, adults and children alike, suffer greatly. Therefore, it was important to look into this topic and research the background and information of malathion. Works Cited Bhu05: , (Mehta and Mehta 1015), Uni08: , (United States Environmental Protection Agency), Tho10: , (Maugh), Tom06: , (Tomlin 642-643), Mas82: , (Massoulie and Bon), Rob98: , (Roberts 360-367), Read More