detoxification of xenobiotics ppt biochemistry vkunder637@gmail.com
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DETOXIFICATION OF XENOBIOTICS
Dr Vijay MarakalaBiochemistry
SIMS&RC
DETOXIFICATION OF XENOBIOTICS
• Detoxification pathways and waste disposal pathways are metabolic pathways devoted to removing toxins that can be present in our diets or in the air we breathe, introduced into our bodies as drugs, or generated internally from the metabolism of dietary components.
DETOXIFICATION OF XENOBIOTICSXe
nobio
tics • Food additives, poisons, toxins,
certain drugs, chemicals, environmental pollutants, pesticides and other foreign substances.
DETOXIFICATION OF XENOBIOTICS
Phases of Detoxification Processes
Phase I Phase II
DETOXIFICATION OF XENOBIOTICS
DETOXIFICATION OF XENOBIOTICS
DETOXIFICATION OF XENOBIOTICSOxidation Alcohol
Aldehydes
Amines
Aromatic hydrocarbons
Sulfur compounds
Drugs
Ethanol → Acetic acid
Methanol → Formic acid
Benzaldehyde → Benzoic acid
Aliphatic amine → Aliphatic acid + Urea
DETOXIFICATION OF XENOBIOTICSOxidation
Most of the oxidation reactions are catalysed by monooxygenase or cytochrom P450
Many reactions of cytochrome P450 involve
the addition of a hydroxyl group to xenobiotics
Hydroxylation
DETOXIFICATION OF XENOBIOTICS
DETOXIFICATION OF XENOBIOTICS
HydroxylationThe
responsible enzymes are
called monooxygen
asesor
cytochrome P450
DETOXIFICATION OF XENOBIOTICS
Cytochrome P450
DETOXIFICATION OF XENOBIOTICS
NADPH +H+
NADP+
NADPH –Cyt P450 reductase
NADPH –Cyt P450 reductase
Cyt P450
Cyt P450
XH
X-OH
oxidised
oxidisedreduced
reduced
O2
H2O
DETOXIFICATION OF XENOBIOTICS
Cytochrome P450
Multiple forms
Hemoproteins
Microsomes of liver
NADPH dependant
Phosphatidyl choline
Inducible enzyme
DETOXIFICATION OF XENOBIOTICS
Hydroxylation
DETOXIFICATION OF XENOBIOTICSReduction
It is less common and less important than oxidation.
DETOXIFICATION OF XENOBIOTICSHydrolysis Many drugs are detoxified by hydrolysis.
DETOXIFICATION OF XENOBIOTICS
Conjugation Glucuronic acid
Glutathione
Sulfate
Glycine
Cysteine
Acetate Glutamin
e
Conjugation means the chemical combination of one
compound with another compound.
DETOXIFICATION OF XENOBIOTICSConjugation with Glucuronic
acid
DETOXIFICATION OF XENOBIOTICS
Conjugation with Glucuronic acid
Benzoic acid + UDP-Glucuronic acid → Benzoyl glucuronide + UDP
Paracetamol + UDP-Glucuronic acid → Conjugated product + UDP
Diclofenac sodium + UDP-Glucuronic acid → Conjugated product + UDP
DETOXIFICATION OF XENOBIOTICS
Conjugation with Glycine
DETOXIFICATION OF XENOBIOTICS
Conjugation with Glutathione
DETOXIFICATION OF XENOBIOTICS
X-R + GSH
X-S-G
S-X-Cysteinylglycine
S-X-Cysteine
Mercapturic acid
RH
Glutamine
Glycine
Acetyl-CoA
CoA-SH
Glutathione S-transferase
γGlutamyl hydrolase
Cysteinylglycinase
N-Acetyl transferase
Conjugation reaction by glutathione
DETOXIFICATION OF XENOBIOTICS
Conjugation with Glutatmine
Phenylacetate
Phenylacetyl glutamine
Glutamine
DETOXIFICATION OF XENOBIOTICS
Conjugation with sulfate
DETOXIFICATION OF XENOBIOTICS
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