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25 Cards in this Set
- Front
- Back
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What are BChEs?
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butyrylcholinesterase "pseudocholinesterase"- do not act in nerves
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What does the breakdown of ach by ache make?
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CHOLINE AND ACETIC ACID
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What are the 3 essential amino acids of the "catalytic" triad"?
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Serine, histidine, and glutamate
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How does antidotal 2-PAM
"reactivate" AChE and why is it not necesary for methyl-carbamate inhibitors? |
it dephosphorylates the OP poisoning which would help regenerate acetylcholinesterase
deacyclation regenerates fast decarbamoylation regenerates fast methyl-carbamates are unstable in the first place while the OPs are stable |
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What is aging?
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The OP is attached and after time the OP will stay in the ester site and 2-PAM will longer work. No AChE regeneration
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What are the need for OPs and its resistance problems?
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Pre-OP were chlorinated hydrocarbons (CHC) poor on mites and many sucking insects and nicotine is not so effective. OPs filled this gap
Has major resistance problems like cross resistance |
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What is the main point of OPs in history?
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They were used as chemical warfare agents and insecticides (VX gas)
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What is Sarin?
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Sarin is a chemical warfare agent, rapid aging of phosphorylated AChEs so difficult to reactivate
High acute tox to man and volatile |
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Recognize the OP STRUCTURES! What are some stability issues with OPs?
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Unusually unstable in alkali-cleaves anhydride bond, P=S more stable than P (triple bond) O
THERMAL instability |
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Describe OP activation during metabolization.
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Detoxed by esterases and GST enzymes. Activated by phosphorothionate oxidation to OXON (also by thioether oxidation) (DESULFURATES OFF THE PHOSPHATE)
GST REMOVES CH3 ESTERASE CLEAVES OC2H5 |
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What are some pros and cons of plant and animal systemics?
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Plants= longer residue, less damage to predators and parasites
Animal= high specficity, residues in milk |
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What are characteristics of malathoin and dichlorvos?
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Malathoin- safest OP
Dichlorvos- strong fumigant properties- pest strips for slow release |
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How do aromatic or phenyl derivatives compare to aliphatic in terms of stability and persistence?
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Aromatic/Phenyl= more stable and persistent
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What are the tox differences between parathion, methyl parathion and fenitrothion?
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Parathion= high mammalian tox
Methyl Parathion= somewhat safe (dermal) Fenitrothion= low mammal tox |
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What is chlorpyrifos?
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Most important and controversial OP
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What is the mode of action of methylcarbamates (MCs)?
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potent inhibitor of AchE
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What is the natural product history of MCs?
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used for witchcraft trials in West Africa from the calabar bean
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What are the medical uses of MCs?
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parasympathomimetic drugs- for muscle spasms, overdoses of curare, topically for glaucoma
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What is necessary for MCs to be insecticidal?
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They have to be non-ionized
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What are the three classes of MCs for insecticides and some examples?
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1. dimethylcarbamates of heterocyclic enols (no longer used) "heterocyclic enol"
2. methylcarbamates of substituted phenols- frequently simple 3. Aldoxime methylcarbamates |
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How do you generally synthesize MCs? general understanding of nomenclature too..
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ROH +
phosgene and carbonyl chloride or methyl isocyanate.... |
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What caused the accident in Bhopal, India in 1984 and how?
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from ROH + methyl isocyanate which made monoalkyl carbamate and it was released
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Why is carbaryl used more than all other MCs?
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very low mammalian oral and dermal tox and broad spectrum insecticidal for agriculture, lawn and garden
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How would you degrade MCs?
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hydrolysis
many sites of metabolism, BIODEGRADABLE, CYP P450 Photodecomposition |
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What is an antidote for MCs and what isn't?
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Atropine is an antidote and 2-PAM is not
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