reductions and hydrolyses Flashcards
what 4 molecules are likely to undergo reductions?
-aromatic and heteroaromatic nitro compounds
-aromatic azo compounds
-aromatic sulfoxides
-carbonyl groups (ketones and aldehydes)
explain the reduction of aromatic nitro compounds
Ar-NO2
there is a rapid single e- reduction to form a nitro radical. this is a reversible reaction. O2 that we inhale is used to accept the electron to bring back Ar-NO2. GSH is used to bring back molecular oxygen.
the nitro radical can only be reduced to nitroso in the GI tract. once nitroso is formed, it is easy to produce hydroxylamine, and then amine
how can nitro aromatics be reduced?
ONLY by the microorganisms in the GI tract
Ar-NO2 radical is reduced to nitroso, then hydroxylamine, and then amine
what will happen if we administer nitroso parenteral?
it will still easily get reduced to hydroxylamine and then amine.
the problem lies in reducing nitro radical to nitroso
true or false
when nitro radical is produced through rapid reduction, it almost always goes back to the parent molecule
true
with help of molecular oxygen and GSH
____ depletion can occur from the reduction of nitro aromatics
GSH
true or false
if we administer a nitro aromatic parenteral, it will NEVER end with an amine product
true. this will bypass the microorganisms of the GI tract and only they have the capability to reduce nitro aromatics (to nitroso)
what enzyme catalyzes the hydrolyses of carboxy esters?
carboxy esterase (if R connected to O is aliphatic)
if R connected to O is aromatic, it is Aryl esterase
explain the hydrolysis of carboxy esters
accomplished by carboxyesterases
produces corresponding carboxylic acid + alcohol
where are carboxyesterase enzymes found?
in liver microsomes and soluble fraction
where is aryl esterase found
in the plasma
explain the hydrolysis of carboxy esters when the R attached to the O is aromatic
produces phenolic alcohol + corresponding carboxylic acid
what are cyclic esters called
lactones
thioesters are hydrolyzed to produce…
R-SH + carbooxylic acid
There is no direct hydrolysis on nitrite or nitrate esters?
NO DIRECT HYDROLYSIS ON NITRATE (NO3-) must be converted to nitrite
