Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
25 Cards in this Set
- Front
- Back
What are BChEs?
|
butyrylcholinesterase "pseudocholinesterase"- do not act in nerves
|
|
What does the breakdown of ach by ache make?
|
CHOLINE AND ACETIC ACID
|
|
What are the 3 essential amino acids of the "catalytic" triad"?
|
Serine, histidine, and glutamate
|
|
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 |
|
What is aging?
|
The OP is attached and after time the OP will stay in the ester site and 2-PAM will longer work. No AChE regeneration
|
|
What are the need for OPs and its resistance problems?
|
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 |
|
What is the main point of OPs in history?
|
They were used as chemical warfare agents and insecticides (VX gas)
|
|
What is Sarin?
|
Sarin is a chemical warfare agent, rapid aging of phosphorylated AChEs so difficult to reactivate
High acute tox to man and volatile |
|
Recognize the OP STRUCTURES! What are some stability issues with OPs?
|
Unusually unstable in alkali-cleaves anhydride bond, P=S more stable than P (triple bond) O
THERMAL instability |
|
Describe OP activation during metabolization.
|
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 |
|
What are some pros and cons of plant and animal systemics?
|
Plants= longer residue, less damage to predators and parasites
Animal= high specficity, residues in milk |
|
What are characteristics of malathoin and dichlorvos?
|
Malathoin- safest OP
Dichlorvos- strong fumigant properties- pest strips for slow release |
|
How do aromatic or phenyl derivatives compare to aliphatic in terms of stability and persistence?
|
Aromatic/Phenyl= more stable and persistent
|
|
What are the tox differences between parathion, methyl parathion and fenitrothion?
|
Parathion= high mammalian tox
Methyl Parathion= somewhat safe (dermal) Fenitrothion= low mammal tox |
|
What is chlorpyrifos?
|
Most important and controversial OP
|
|
What is the mode of action of methylcarbamates (MCs)?
|
potent inhibitor of AchE
|
|
What is the natural product history of MCs?
|
used for witchcraft trials in West Africa from the calabar bean
|
|
What are the medical uses of MCs?
|
parasympathomimetic drugs- for muscle spasms, overdoses of curare, topically for glaucoma
|
|
What is necessary for MCs to be insecticidal?
|
They have to be non-ionized
|
|
What are the three classes of MCs for insecticides and some examples?
|
1. dimethylcarbamates of heterocyclic enols (no longer used) "heterocyclic enol"
2. methylcarbamates of substituted phenols- frequently simple 3. Aldoxime methylcarbamates |
|
How do you generally synthesize MCs? general understanding of nomenclature too..
|
ROH +
phosgene and carbonyl chloride or methyl isocyanate.... |
|
What caused the accident in Bhopal, India in 1984 and how?
|
from ROH + methyl isocyanate which made monoalkyl carbamate and it was released
|
|
Why is carbaryl used more than all other MCs?
|
very low mammalian oral and dermal tox and broad spectrum insecticidal for agriculture, lawn and garden
|
|
How would you degrade MCs?
|
hydrolysis
many sites of metabolism, BIODEGRADABLE, CYP P450 Photodecomposition |
|
What is an antidote for MCs and what isn't?
|
Atropine is an antidote and 2-PAM is not
|