Download How do drugs work

How do the Anti-HIV drugs woks?
By
Tawitch
Suriyo
Master degree of Toxicology
Mahidol University
How do anti-HIV drugs work?
Content
•The step of HIV life cycle that might be stopped.
•The types of anti-HIV drugs that we have now
•Reverse Transcriptase Inhibitors
•Integrase Inhibitors
•Protease Inhibitors
The step of HIV life cycle that
might be stopped.
4
1.Attachment
2.Reverse
transcriptase
3.Integrase &
transcription
4.Translation
5.viral protease
6.assembly &
budding
1
3
2
5
6
The step of HIV life cycle that
might be stopped.
1.Attachment
The step of HIV life cycle that
might be stopped.
2.Reverse Transcriptase
The step of HIV life cycle that
might be stopped.
3.Integration,Transcription
Viral DNA joins host DNA
Making multiple viral RNAs
The step of HIV life cycle that
might be stopped.
4.Translation
The step of HIV life cycle that
might be stopped.
5.Viral Protease
The step of HIV life cycle that
might be stopped.
6.Assembly & Budding
The step of HIV life cycle that
might be stopped.
Types of anti-HIV drugs that we
have now.
•Reverse Transcriptase Inhibitors
•Integrase Inhibitors (clinical trial)
•Protease Inhibitors
Reverse Transcriptase Inhibitor
•Nucleoside analog
E.g. AZT,ddI,ddC,d4T
•Non-nucleoside analog
E.g. Nevirapine,Delavirdine
Reverse Transcriptase Inhibitor
Nucleoside analog
•These agents are both inhibitors
and substrates of RT, broad in family
of 2’-3’-dideoxynucleoside
•Need metabolism before functional
•Competitive inhibition with dNTP
•Incorperation into the viral DNA
lead to DNA termination
Reverse Transcriptase Inhibitor
Nucleoside analog need metabolize
Reverse Transcriptase Inhibitor
Nucleoside analog
+Incorporation lead
to DNA chain
termination
Reverse Transcriptase Inhibitor
Nucleoside analog : Zidovudine or AZT
+
+
+
+
Thymidine analog
3’-azido-2’,3’-dideoxythymidine
MW 267.24
fomular
C10H13N5O4
Reverse Transcriptase Inhibitor
Nucleoside analog : Zidovudine or AZT
The mechanism of action of AZT
+Metabolize of AZT
Reverse Transcriptase Inhibitor
Nucleoside analog : Zidovudine or AZT
AZT-DP bind with NDP-K
Reverse Transcriptase Inhibitor
Nucleoside analog : Zidovudine or AZT
AZT-TP
+competitive inhibit RT with respect
to TTP
+incorporate into growing chain of
DNA
+AZT reduce the amount of dNTP
(decreasing competition for AZT-TP)
Reverse Transcriptase Inhibitor
Nucleoside analog : Zidovudine or AZT
AZT-TP
+Low concentration onhibit DNA
polymerase
+distrub growing of cellular DNA
chain
Reverse Transcriptase Inhibitor
Non-nucleoside analog
•Structurally heterogenous
•Active for HIV-1 only
•Not need metabolism before functional
•Interact with a nonsubstrate binding
site
• Noncompetitive inhibition
Reverse Transcriptase Inhibitor
Non-nucleoside analog : Nevirapine
•Viramune (trade name)
•MW 266.3
•fumular C15H14N4O
Reverse Transcriptase Inhibitor
Non-nucleoside analog : Nevirapine
The machanism action of nevirapine
+bind directly to RT
+block RT activity (RNA
dependent and DNA-dependent DNA
polymerase) by distrub the RT’s
catalytic site (110 Asp,185Asp and 186
Asp triad)
Reverse Transcriptase Inhibitor
Non-nucleoside analog : Nevirapine
+not compete with template or
nucleoside tritposphate
+not inhibit HIV-2 RT and cellular
DNA polymerase
Integrase Inhibitor
•HIV integrase is a viable therapeutic strategy
that will abort completion of the viral life cycle
•The commercial drug of this type not
have yet now.
•Some drug just under clinical trial.
E.g. Zintevir currently in Phase I/II
clinical trial.
Integrase Inhibitor
Overview of integration
•the formation of the ISC
•the 3’-processing in reaction
•the DNA strand transfer
Integrase Inhibitor
HIV-Integrase
•a protein of 32 kDa
•function for intergrate viral cDNA into human DNA
•recognizes specific sequence in LTR in viral cDNA
•composed of 3 functional domain
•active form is oligomer ( by oligomerization)
Integrase Inhibitor
Different approches to interfering the
integration
•triple helix-mediated inhibition
•inhibition IN by peptides derived from
combinatirial peptides chemistry.
•Screening of chemical libraries and
natural compounds.
•Inhibition by G-quartet forming
oligonucleotides
Integrase Inhibitor
Triple helix-mediated inhibition
•oligonucleotide readly form stable
complex with viral DNA
•triplex formation prevent catalytic
function of IN
Integrase Inhibitor
Inhibition IN by peptides derived from
combinatirial peptides chemistry
•.find critical potion of IN by change
amino acid that make IN loss its
functional
Integrase Inhibitor
Screening of chemical libraries and
natural compounds.
•.find the chemical ( oligonucleotide-base)
that inhibit function of IN .
•Device into 3 categories
• +DNA binding agent
• +Polyhydroxylated aromatic compound
• +Nucleotides
Integrase Inhibitor
Inhibition by G-quartet forming
oligonucleotides
•oligonucleotides composed of base
deoxyguanosine and thymidine
•in presence of K+, Its form G-quartet
•G-quartet can inhibit HIV replication by
•
+inhibit viral entry into cell
•
+and/or inhibition HIV IN
Integrase Inhibitor
Zintevir or AR-177
•stable oligonucleotides of 17 nucleotides
•composed only deoxyguanosine and
thymidine,with single phosphorothioate
internucleoside linkages at 5’ and 3’ end.
•Fumular
•
5’-GTGGTGGGTGGGTGGGT-3’
Integrase Inhibitor
Zintevir or AR-177
•Form a highly stable
intramolecular fourstranded DNA contain two
stacked G-quartet
•Zintevir (G-quartet) inhibit
HIV-1 IN activity
Integrase Inhibitor
Zintevir or AR-177
The machanism of action of Zintevir
•its inhibit integration in only step of the
formation of ISC by
• +G-quartet interact with IN
• +it not bind to DNA binding domain
but its interact with zinc finger domain
of IN
• +IN can’t form active form (oligomer)
• +IN can’t bind with viral DNA
Protease Inhibitor
Protease enzyme
•As aspartyl protease.
•Consist of 2 symmetric subunit
•each subunit consist 99 amino acid
•single active site
•catalytic site conserve catalytic
triads ( Asp-Thr-Gly)
Protease Inhibitor
Protease enzyme
•Cleavage polypeptide to functional
enzyme and structural protein
•muation in catalytic site (Asp->Ala)
cause immature virus (can’t infect new
cell)
•HIV protease no cross-reactivity with
human cellular protease
Protease Inhibitor
Activities of HIV protease enzyme
Protease Inhibitor
Protease inhibitor
•Slow down the action of HIV protease
•e.g. Ritonavir, Indinavir,Saquinavir
Protease Inhibitor
Protease inhibitor
•Base on transitionstate mimetics of
peptide substrate
•interact with catalytic residues and
displace a structural water molecule
•the interaction protease and protease
inhibitor complex cause enzyme not
functional properly.
Protease Inhibitor
Native HIV Protease
HIV Protease with
inhibitor
Protease Inhibitor
Protease inhibitor : Ritonavir
•Norvir (trade name) or ABT-583
•a white-to light-tan powder
•formular C37H48N6O5S2
•MW 720.95
Protease Inhibitor
Protease inhibitor : Ritonavir
•A peptidomimetic inhibitor for HIV1,2 protease
•Its directly interact with HIV
protease that cause this enzyme not
function
•the interaction is hydrophobic
interaction
Protease Inhibitor
Protease inhibitor : Ritonavir
•hydrophobic interaction of P’3
isopropylthiazolyl group of ritonavir
with active side chain of valine-82
(V82) of HIV protease
•mutation in V82 to Ala,Phe or Thr
cause ritonavir resistance
Protease Inhibitor
Protease inhibitor : Ritonavir
•Its metabolized by CYP 3A4
•and also a potent inhibitor of CYP 3A4
•inhibition of CYP by the unhindered
nitrogen atom on the unsubatituted P2’
5-thiazolyl group with bind directly to
the heme in the CYP active site
Protease Inhibitor
Protease inhibitor : Ritonavir
P3’
isopropylthiazoly group
P2’ 5thiazoly group
Protease Inhibitor
•Protease - Ritonavir inhibitor complex.
Thank you for your attention