Download Mechanistic Classes of Antibacterials

Mechanistic Classes of Antibacterials
Benjamin D. Horning
Group Meeting November 30, 2011
http://images.agoramedia.com/cs/eh/cs_diarrhea_antibiotics_causing_diarrhea_article.jpg
http://www.irishhealth.com/content/image/853/Image1.jpg
Walsh, C. T. Antibiotics: Actions, Origins, Resistance, American Society for Microbiology Press, Washington DC, 2003
Antibacterials- A Subclass of Antibiotics
An antibiotic is “a chemical substance having the capacity, in dilute solution, to kill or inhibit growth of
microorganisms.” This definition includes antifungals and antiprotozoals. Antibiotics travel inside the body
to fight microorganisms, antiseptics are used externally, and disinfectants are for non-living surfaces.
antimicrobials
antibiotics
disinfectants
antiseptics
antibacterials
antifungals
antiprotozoals
applied to nonliving objects
for external applications
to living organisms
for internal or
external use
kill fungus
kill protozoans
(single-celled eukaryotes)
http://www.lysol.com/images/products/no-mess-automatic-toiletbowl-cleaner.png, http://www.couponmamacentral.org/wp-content/uploads/2011/09/purell.jpg,
http://www.medexpressrx.com/blog/wp-content/uploads/2010/07/antibiotics4.jpg, http://drugster.info/drug/medicament/22969/,
http://modernmedicalguide.com/wp-content/uploads/2010/03/Antiprotozoal-Drugs.jpg
Antibacterials- A Subclass of Antibiotics
human antibacterials
in vitro antibacterials
S. pyogenes
veterinary and feedstock
antibacterials
S. mutans
S. pneumoniae
Streptococcus pyogenes - strep throat, rheumatic fever, scarlet fever, necrotizing fasciitis
Streptococcus pneumoniae - (bacterial) pneumonia
Streptococcus agalactiae - meningitis, (bacterial) pneumonia
Escherichia coli - gastroenteritis, urinary tract infections, sepsis, diarrhea
(Methicillin-resistant) Staphylococcus aureus (MRSA) - Imepetigo, Staph infections, toxic shock syndrome
Image from: http://inst.bact.wisc.edu/inst/images/book_3/chapter_13/13-3.jpg
http://www.webcitation.org/5uJyti0mG
http://www.medicinenet.com/sepsis/page4.htm
Top-Selling Antibiotics in the USA
O
21
F
CO2H
N
Me
N
54
Me
N
Me
N
H
Me
94
Me
OH
Me
OH
Levaquin (Levofloxacin)
O
OH
Me
Me
N
OH
H
OH
NH2
O
O
OH
O
CO2H
OH
O
O
Medicis
$673 Million
O
125
OH
Doryx (Doxycycline)
Medicis
$673 Million
O
F
OH
Solodyn (Minocycline)
Ortho-McNeil
$1,355 Million
F
CO2H
O
126
F
H
CO2H
H
N
HN
N
N
N
N
HN
OMe
H
H
Avelox (Moxifloxacin)
Ciprodex otic
(Cipro and Dexamethasone)
Merck
$353 Million
138
N
160
O
Me
O
Zyvox (Linezolid)
Pfizer
$223 Million
Alcon
$253 Million
OH
166
OH
O
O
O
Cl
HO
H O H
N
N
O
H H
O
N H
H
HO
O
HO
OH
O
O
Me
H
N
HO
Me
H3N
HO
F
Vigamox (Moxifloxacin)
Alcon $255 Million
O
N
N
HN
OMe
O
H
NH2
N
O
97
Me
H
O
Me
H
Me
Me
N
OH
H
Cl
O
N
H
O
N
O
H
OH Me
O
N
H
OH
Me
NHMe
NH2
NH2
OH
O
OH
OH
O
O
Oracea (Doxycycline)
OH
Vancocin (Vancomycin) ViroPharma
$192 Million
Galderma
$187 Million
http://cbc.arizona.edu/njardarson/group/top-pharmaceuticals-poster
Antibiotics- Why You Should Care
of 57 million annual deaths
Vaccinations and antibiotics can cure or prevent the
majority of infectious diseases currently afflicting humanity.
Antibiotic use introduces evolutionary selection pressure to
bacteria; Resistant strains are selected for, and cause
antibiotics to become ineffective.
Bacterial resistance has been observed for every class of
antibiotic introduced, sometimes within one year.
New therapies will be needed.
Graph from: Morens, D. M.; Folkers, G. K.; Fauci, A. S. Nature 2004, 430, 242-249
Table from: Palumbi, S. R. Science 2001, 293, 1786-1790
Strategies to Slow the Development of Antibiotic Resistance
108 bacteria
107
one error per
bases
10 mutants (~0.3% of genes)
antibiotic
treatment
1 bacterium
selection for
resistant bacteria
bacterial
growth
108 bacteria
completely resistant
Overkill (multiple antibiotics) has worked well for HIV/AIDS, but not always applicable for bacteria (side effects).
Direct observation therapy - continue antibiotic dose until no bacteria remain (not practical).
Use narrow-spectrum antibiotics when applicable.
Withhold the most powerful drugs - prevented vancomycin resistance for >30 years - difficult business model for pharma.
Continue to develop new therapies and improve old therapies.
Palumbi, S. R. Science 2001, 293, 1786-1790
Bacterial Resistance - Three Flavors
Three types of bacterial resistance to antibiotics have been observed, coming either from
random mutation under the selection pressure of antibiotics, or from antibiotic-producing
bacteria. Resistance can be spread amongst bacteria via horizontal gene transfer.
NH2
N
N
O
H
N
Ph
S
O
N
O
Me
Me
N
O
N
O
OH
CO2H
H2O
RlmN
Cfr
!-lactamase
NH2
Ph
N
O
S
OH
N
Me
NH
O
HN
N
Me
O
Me
N
Me
O
CO2H
O
export pumps
(efflux)
antibiotic modification
(only natural products
and semisynthetics)
OH
enzymatic target
modification
http://www.sciencephoto.com/image/151999/530wm/C0089313-Active_efflux,_artwork-SPL.jpg
Fujimori, D. G. et. al. J. Am. Chem. Soc. 2010, 132, 3953-3964
Paul Ehrlich and Drug Discovery
Made seminial contributions in histology, haematology, immunology,
oncology, microbiology and pharmacology.
Alongside Ilya Mechnikov, won the Nobel Prize in Physiology or Medicine in
1908 “in recognition of their work on immunity.”
Most famous for his discovery of Salvarsan (arsphenamine, #606), a
compound for the treatment of syphilis, which was discovered during the
first screen of a library of compounds for pharmaceutical activity, and later
part of the first optimization of a lead, becoming the first blockbuster drug
and presaging modern drug discovery.
H2N
HO
OH
HO
H2N
NH2
Paul Ehrlich and Sahachiro Hata
Frankfurt 1910
As
As
As
As As
NH2
As
As
As
As
As
OH
OH
HO
NH2
HO
NH2
H2N
HO
NH2
NH2
NH2
Revised structure of Salvarsan
OH
OH
Bosch, F.; Rosich, L. Pharmacology 2008, 82, 171-179 www.nobelprize.org/nobel_prizes/medicine/laureates/1908/
Salvarsan
http://pubs.acs.org/cen/coverstory/83/8325/8325salvarsan.html
Lloyd, N. C.; Morgan, H. W.; Nicholson, B. K.; Ronimus, R. S. Angew. Chem. Int. Ed. 2005, 44, 941-944
The Four Major Targets of Antibiotics
Walsh, C. T. Nature Reviews Microbiology 2003, 1, 65-70
Walsh, C. T. Antibiotics: Actions, Origins, Resistance, American Society for Microbiology Press, Washington DC, 2003
The Four Major Targets of Antibiotics
Antibiotics either target processes that are unique to bacteria - cell wall biosynthesis and folate
metabolism - or processes that have different enough machinery to allow selective inhibition of bacterial
over human versions - protein biosynthesis and DNA and RNA replication and repair.
O
O
NH2
S
S
NH2
O
H2N
Sulfanilamide - 1936
S
O
N
H2N
O
NH2
O
N
Prontosil - 1932
H
N
Sulfacetamide
S
CO2H
HN
H2N
N
N
H
N
H
HO2C
O
H
N
Me
O
O
Me
H2N
O
O
H
N
N O
H2N
Sulfamethoxazole
N
H
Tetrahydrofolic acid
NH2
OMe
N
H2N
N
OMe
OMe
Trimethoprim - 1940s
Walsh, C. T. Nature Reviews Microbiology 2003, 1, 65-70
Walsh, C. T. Antibiotics: Actions, Origins, Resistance, American Society for Microbiology Press, Washington DC, 2003
Antibacterials Inhibiting Bacterial Folate Biosynthesis
Prontosil was the first sulfa drug, discovered by
Gerhard Domagk while working for Bayer AG.
O
Bayer AG hoped to use its expertise in dyes to
develop a Ehrlich-style “magic bullet” dye that could
be selective for pathogenic bacteria, found Prontosil.
Immensely successful as the first broad-spectrum
antibiotic.
O
N
H2N
NH2
S
NH2
N
Prontosil - 1932
Bayer AG’s revenue stream was undercut when a
team of French scientists found that Prontosil is a
prodrug, and becomes sulfanilamide in the body, the
patent for which had long ago expired.
in vivo
metabolism
O
S
Gerhard Domagk
Nobel Prize 1939
“for the discovery
of the antibacterial
effects of prontosil”
Massive product and marketing of sulfanilamide
followed; One preparation, called Elixir
Sulfanilamide, was a solution in ethylene glycol.
This raspberry-flavored concoction caused over
100 deaths in 1937.
NH2
O
In 1938, the FDA passed the Federal Food, Drug
and Cosmetic Act, requiring safety tests for a
variety of product. This is why we do clinical trials
for all new medicines today.
H2N
Sulfanilamide - 1936
http://www.nobelprize.org/nobel_prizes/medicine/laureates/1939/domagk.html#
http://www.fda.gov/AboutFDA/WhatWeDo/History/ProductRegulation/SulfanilamideDisaster/default.htm
for a history of clinical trials, see:
http://blogs.scientificamerican.com/guest-blog/2011/10/06/molecules-to-medicine-clinical-trials-for-beginners/
Sulfa Drugs - Tetrahydrofolate Biosynthesis in Bacteria
O
N
HN
H2N
O
O
O
O
P
P
P
O-
O
O-
O
OH
N
N
H
para-amino
benzoate
H2N
N
HN
CO2H
H2N
O
O-
O
O
P
O-
OH
H
N
O
S
N
N
H
Me
O
H2N
7,8-Dihydropteroate Synthase
7,8-Dihydropteroate Synthase
H
N
O
CO2H
O
N
HN
H2N
N
S
O
N
H
H2N
N
HN
H2N
N
N
H
7,8-Dihydrofolate
O
CO2H
N
H
N
H
N
H
7,8-Dihydropteroate
O
N
N O
N
H
7,8-Dihydropteroate
O
Me
O
N
HN
N
H
N O
O
NADPH
HN
HO2C
H2N
N
H
N
CO2H
N
H
N
H
HO2C
N
H
5,6,7,8-Tetrahydrofolate
Sulfa Drugs - Tetrahydrofolate Biosynthesis in Bacteria
O
O
N
HN
H2N
O
O
P
P
O-
O
O-
O
OH
S
N
H
HN
H2N
N
NH2
N
H
H2N
N
H
7,8-Dihydropteroate
HN
N
H
H2N
N
N
H
O
P
O-
OH
H
N
O
Me
O
O
N O
H2N
7,8-Dihydropteroate Synthase
H
N
O
S
Me
George H.
O Hitchings
N O
Nobel Prize 1988
HN
N
H “for their discoveries of
N
OMe
important principles for
H2N
N
N
OMe
H
drug treatment”
7,8-Dihydropteroate
Trimethoprim
OMe
N
O
CO2H
O
N
O-
S
combination
marketed as
co-trimoxazole
N
O
N
H
CO2H
N
O
O
H2N
N
N
Sulfamethoxazole
7,8-Dihydropteroate Synthase
O
Me
P
H2N
para-amino
benzoate
H2N
O
O
N O
HN
CO2H
N
H
N
O
O
NADPH
HN
HO2C
H2N
N
H
7,8-Dihydrofolate
N
CO2H
N
H
H
N
N
H
HO2C
N
H
5,6,7,8-Tetrahydrofolate
Success and Failure with Bacterial Metabolite Biosynthesis
OH
O
OH
O
Me
O
OH
platensymicin
O
O
Me
n
O
HN
OH
n
Me
n
fatty acid biosynthesis
N
H
H2N
O
N
H
N
CO2H
N
H
N
H
HO2C
N
H
Folate is an essential nutrient for humans,
they cannot synthesize it.
Bacteria must synthesize folate, and cannot
obtain it from their environment.
Zlitni, S. and Brown, E. D. Nature 2009, 458, 39-40
Walsh, C. T. Antibiotics: Actions, Origins, Resistance, American Society for Microbiology Press, Washington DC, 2003
The Four Major Targets of Antibiotics
H
N
Ph
S
O
Me
Penicillin G
Me
N
O
CO2H
Me
N
O
H
N
S
S
N
O
CO2H
HO
H
N
O
H
O
HO
O
O
O
Cl
O
O
Cl
HO
HO
OH
O
Me
H
N
O
O
H
N
H
O
H
H
N
H
OH
OH Me
O
O
Me
N
N
H
O
OH
Cefepime (cephalosporin)
OH
Me
H3N
HO
N+
N
O
H2N
H
H
NHMe
NH2
Vancomycin (peptidoglycan)
Antibacterials that Target Cell-Wall Biosynthesis
Images from: http://fernness.com/science-01.html
Antibacterials that Target Cell-Wall Biosynthesis
Transglycosylases
MurG
MurB
MurC
Transpeptidase
β-lactams
MurD
MurF
Cell wall allows cells to
survive in hypotonic media,
where other wise swelling
of the cell would cause it to
burst.
Murein , greek word for
wall, enzyme called MurAG
The cell wall is called murein, from the greek word for wall, and the
enzymes involved in its construction are hence named MurA, MurB, etc.
Images from: Höltje, J.-V. Microbiol. Mol. Biol. Rev. 1998, 62, 181-203
β-Lactams: Penicillins, Cephalosporins and Carbapenems
H OH
Me
O
H OH
H O
O
H
HN
H O
O
NHAc HO
H
H
NHAc
Me
H
O
H OH
H O
O
O
HN
O
NH
HO2C
NHAc
H
O
Me
O
H
O
O
Me
NH
O
-D-Ala
TPase
O
NH
O
NH2
NH
HO2C
O
CO2H
Me
NH
NH
O
CO2H
O
NH2
HN
HO2C
NH
O
HO2C
Me
O
N
H
-TPase
O
R
NH
Me
S
O
NH
O
Me
TPase
O
NH
S
Me
CO2H
NH
O
Ph
OH
N
O
O
Me
H
N
Ph
NH
O
Me
O
TPase
HN
CO2H O
N
H
O
NH
Me
H
Me
CO2H
Covalent intermediates have half-lives
from several hours to many days
Walsh, C. T. Antibiotics: Actions, Origins, Resistance, American Society for Microbiology Press, Washington DC, 2003, p. 39
Discovery of Penicillin: Nobel Prize1945
Sir Alexander Fleming
Sir Howard Florey
"for the discovery of penicillin and its curative
effect in various infectious diseases"
Dr. Ernst B. Chain
assisted by Sir. Robert Robinson
http://www.nobelprize.org/nobel_prizes/medicine/laureates/1945/
β-Lactams: Penicillins, Cephalosporins and Carbapenems
H
N
Ph
S
O
N
Me
N
O
R
CO2H
Penicillin G
(penicillin)
Me
N
S
Me
thiazolidine
O
H
N
S
S
S
N
O
N+
N
R
O
H2N
N
CO2H
Cefepime
(cephalosporin)
HO
NH2
H
Me
N
O
dihyrothiazine
S
CO2H
Thienamycin
(carbapenem)
N
R
dihydropyrrole
Structural modifications allow decreases susceptibility to β-lactamases.
β-Lactams: Resistance Mechanisms - β-Lactamases
Costs of over $30 billion per year due to β-lactamase-mediated resistance
Ph
NH
O
H
N
Ph
Ph
S
O
!-lactamase
Me
H2O
Me
N
O
Enz
S
O
H2O
Me
Me
HN
O
NH
O
O
S
OH
Me
HN
CO2H
CO2H
Me
CO2H
OH
inactive
Enz
Me
N
S
O
H2N
H
N
S
S
N
O
N
N
N+
O
H2N
OH
NH
N
O O
Me
H2O
!-lactamase
Me
O
CO2H
S
O
Enz
HN
H2O
Me
slower
N+
CO2H
Enz
larger side chain slows hydrolysis by
occluding water from the active site
Statistics from: Palumbi, S. R. Science 2001, 293, 1786-1790
β-Lactams: Resistance Mechanisms - β-Lactamase Inhibitors
HO
Clavulanic acid (right) shows minimal activity against transpeptidases
(penicillin-binding proteins) but is highly active against β-lactamases.
N
A combination of Clavulanate and Amoxicillin is marketed by
GlaxoSmithKline as Augmentin (and by Pfizer as Clavamox)
O
O
O
CO2H
HO
HO
!-lactamase
N
O
O
Enz
HO
O
O
HN
O
H+
Enz
O+
HN
O
CO2H
CO2H
CO2H
OH
Enz
Nuc
Enz
Nuc
O
Enz
O
H
Enz
Nuc
O
O
Enz
O
+H
Enz
O
2N
Enz
CO2H
OH
O
O
+HN
H+
CO2H
OH
Statistics from: Palumbi, S. R. Science 2001, 293, 1786-1790
Aminoglycosides:Vancomycin and Teicoplanin
HO
Me
H3N
HO
H
N
O
H
O
HO
O
H
N
O
O
H
N
H
O
H
H
N
H
H
H
Me
O
HO
HO
Me
O
NH2
N
H
O
N
H
H
N
O
O
HN
NH2
HN
HO2C
O
HO
OH
O
H
N
NH
O
NHMe
O
Cl
O
O
N
N
H
O
OH
OH Me
O
O
Cl
O
OH
O
OH
O
O
Cl
Cl
HO
HO
O
N
H
Me
O
O
Me
Me
OH
O
OH
OH
O
OH
HO
O
HO
OH
OH
O
HO
OH
OH
vancomycin
“The antibiotic of last resort”
Discovered in soil sample from Borneo, isolated by Eli
Lilly chemist Edmund Kornfeld
>30 years before resistance observed (1953 to 1987)
teicoplanin
Marketed by Sanofi-Adventis
Approved in 2009
Chen, L.; Walker, D.; Sun, B.; Hu, Yanan; Walker, S.; Kahne, D. Proc. Nat. Acad. Sci. 2003, 100, 5658-5863
Aminoglycosides:Vancomycin and Teicoplanin
Aminoglycosides:Vancomycin Resistance
HO
H3N
Me
H
H
N
H
Me
O
H
N
H
Me
N
N
H
H
O
OH
OH Me
O
O
H
HO
NH2
R
H
N
Me
H
H
N
H
O
OH
N
N
H
H
H
Me
NH
NH2
Me
R
O
O
N
H
O
Me
O
Me
O
N
H
Me
OH
O
O
H
OH Me
O
O
O
O
O
N
O
H
N
H
O
HO
OH
O
H
Cl
O
O
H
N
O
Me
O
Cl
HO
NH
O
O
O
H
N
H
O
HO
HO
O
OH
O
Cl
O
O
H
N
O
HO
O
Cl
HO
H3N
O
O
OH
Me
OH
O
HO
HO
OH
Me
Removing this single hydrogen-bond interaction reduces vancomycin affinity for the terminal
dipeptide by 1,000-fold. Replacing the terminal D-Ala with D-Ser reduces affinity by 6-fold
Aminoglycosides:Vancomycin Resistance
HO
H3N
Me
H
N
O
HO
H
O
HO
O
O
H
N
O
HO
H
O
H
Me
H
N
H
H
R
NH2
Me
N
H
H
Me
H
Me
HO
H
H
N
O
O
H
H
H
OH
R
N+
H
H
N
H
OH Me
O
O
O
H
N
N
N
H
H
O
Me
H
Me
NH
NH2
OH
Me
O
O
Me
Cl
O
O
N
O
H
N
O
NH
O
Cl
HO
O
HO
OH
O
N
N
H
O
OH
OH Me
O
O
O
O
O
O
H
N
OH
O
Cl
Cl
HO
H3N
O
O
OH
Me
OH
O
HO
HO
OH
Me
N
H
O
O
O
O
Me
Removing this single hydrogen-bond interaction reduces vancomycin affinity for the terminal
dipeptide by 1,000-fold. Replacing the terminal D-Ala with D-Ser reduces affinity by 6-fold
Boger, 2011 showed that activity can be returned by replacing the amide with an amidine
Xie, J.; Pierce, J. G.; James, R. C.; Okano, A.; Boger, D. L. J. Am. Chem. Soc. 2011, 133, 13946-13947
The Four Major Targets of Antibiotics
O
Me
Me
HO
OH
Me
Et
HO
O
O
O
O
Me
OH
NMe2
O
O
Me
O
N
O
H
N
F
OMe
O
N
Me
O
Me
OH
Me
Erythromycin
(Macrolide)
Linezolid
(Oxazolidinone)
OH
Me
H
N
H
Me
OH
NH2
OH
O
OH
OH
O
O
Tetracycline
Antibiotics Blocking Bacterial Protein Biosynthesis
transcription
DNA
translation
RNA
Me
protein
Figure from: Steitz, T. A. Nat. Rev. Mol. Cell Biol. 2008, 9, 242-253
Antibiotics Blocking Protein Biosynthesis: Erythromycin
O
Me
O
Me
HO
Me
OH
Me
Et
HO
Me
OH
HO
O
O
NMe2
O
Me
N
Me
Et
O
OH
N
OMe
O
Me
O
Erythromycin
Me
OH
Me
O
OH
O
Me
Me
Et
O
Me
N
Me
OH
O
Me
O
OH
Me
N
O
Me
HO
O
NMe2
O
Me
OH
Me
O
O
Me
Erythronolide
(Erythromycin aglycone)
Telithromycin
First isolated by Eli Lilly Scientist J. M. McGuire from soil samples collected by A. Aguilar which contained
Saccharopolyspora erythraea, a species of actinomycete (major group of antibacterial-producing bacteria)
Acid-instability hampered widespread application of early derivatives; Mono-deglycosylation, C-6
methylation and carbamate introduction aided in newer generations.
First total synthesis: Woodward, R. B. et. al. J. Am. Chem. Soc., 1981, 103, 3210–3213
Erythromycin Binds to the Ribosome Exit Tunnel
Image from: http://www.weizmann.ac.il/sb/faculty_pages/Yonath/10A-1.jpg
Figure from: Schlünzen, F. et. al. Nature 2001, 413, 814-821
Antibiotics Blocking Protein Biosynthesis: Erythromycin
dimethylation or adenosine
replacement causes resistance
- humans have guanosine
Colored lines indicate
groups that are <4.4 Å
apart
Figure from: Schlünzen, F. et. al. Nature 2001, 413, 814-821
Erythromycin Resistance in Bacteria
O
Me
O
Me
Me
OH
Et
Me
O
O
Me
O
OleI
Me
O
OMe
O
Me
Me
O
OR2
OMe
O
Me
Me
OH
Me
O
Me
OH
Et
OR1
O
Me
OH
O
Me
OleB
NMe2
HO
O
R1=
O
Me
HO
R2=
O
Me
O
Me
Me
OH
Et
Me
O
O
Me
O
OleR
OMe
O
Me
O
Me
OH
Me
O
Me
O
NMe2
O
Me
Me
OH
Et
OR1
O
OH O
O
O
Me
HO
HO
OR2
OMe
O
Me
O
Me
OH
Me
Adapted from: Quiros, L. M. et. al. Mol. Microbiol. 1998, 28, 1177-1185
Antibiotics Blocking Protein Biosynthesis: Linezolid (Zyvox)
O
O
N
N
O
H
N
F
Me
O
Linzeolild (Zyvox)
Pfizer, $223 million in 2010
Antibacterial effects of oxazolidinone originally discovered by
DuPont, abandoned due to toxicity issues. Pharmacia/Upjohn
later salvaged the product and (after being incorporated by
Pfizer) released Zyvox in 2000.
To date, Zyvox is the only oxazolidinone clinically approved,
but many others are currently in clinical trials
Represents the first widely-used novel antibiotic structural class
since the 1960s (fluoroquinolones)
Differences in binding site between other protein biosynthesis
inhibitors prevents cross-resistance
Structure from: Ippolito, J. A. et. al. J. Med. Chem. 2008, 50, 3353-3356
Antibiotics Blocking Protein Biosynthesis: Tetracycline
O
O
N
N
O
H
N
F
Me
O
O
Me
Me
HO
OH
Me
Et
Macrolides and
oxazolidinones interact
with the 50S ribosomal
subunit
Me
OH
NMe2
HO
O
O
O
O
OMe
O
Me
Me
OH
O
OH
Tetracyclines interact
with the 30S
ribosomal subunit
Me
Me
Me
H
H
N
Me
OH
NH2
OH
O
OH
OH
O
O
Figure from: Williamson, J. R. Nature 2000, 407, 306-307
Antibiotics Blocking Protein Biosynthesis: Tetracycline
Cl HO Me
H
Me
N
Me
H
Me
Me
N
HO Me OH
H
H
OH
OH
OH
NH2
OH
O
OH
OH
O
Me
H
H
N
Me
OH
NH2
O
OH
chlorotetracycline
(aureomycin)
O
OH
OH
NH2
O
O
OH
O
OH
OH
O
O
tetracycline
(acromycin)
oxytetracycline
(terramycin)
Chlorotetracycline (aureomycin) was the first tetracycline antibiotic,
discovered in a soil sample in 1948 (again biosynthesized by actinomycetes)
Oxyotetracycline (terramycin) was subsequently discovered in 1949 by a
nascent Pfizer, and was the subject of the first mass-marketing drug campaign.
This drug put Pfizer on the map.
R. B. Woodward and Pfizer collaborated to solve the structure of terramycin,
mostly succeeding (mis-assigned one stereocenter)
Hydrogenation of aureomycin gave the deschloro product, which maintained
activity, and was one of the first semi-synthetic antibiotics.
Baran group meeting on Tetracyclines (http://www.scripps.edu/chem/baran/html/meetingschedule.html)
Chopra, I.; Roberts, M. Microbiol. Mol. Biol. Rev. 2001, 65, 232-260
Novel Tetracyclines from Tetraphase
Me
F
H
H
N
OH
O
N
N
H
Me
NH2
OH
O
OH
OH
O
O
TP-434
Andrew G. Myers
Profssor of Chemistry
Harvard University
Fully synthetic tetracyclines overcome
bacterial resistance problems in ways
that semisynthetics are unable to.
Business plan includes developing new
broad spectrum antibiotics as well as
narrow-spectrum inhibitors.
http://tphase.com/
Antibiotics Interfering with DNA Replication and Transcription
OH
OH
Me
Me
HO
O
O
Me
O
Me
Me
O
Novobiocin
O
OH
H2N
H
N
O
O
O
F
CO2H
Me
N
CO2H
N
N
N
HN
Me
Nalidixic acid
Ciprofloxacin
O
O
F
F
CO2H
CO2H
H
N
N
N
Me
O
N
HN
N
OMe
Me
H
Levofloxacin
Moxifloxacin
Fluoroquinolones Affecting DNA Replication and Transcription
O
CO2H
Me
N
Nalidixic acid was the first synthetic quinolone antibiotic, formed as a
byproduct during chloroquine (anti-malarial) manufacture in the early 1960s.
N
Me
Nalidixic acid
O
F
Ciprofloxacin, or Cipro, is a second-generation fluoroquinolone, patented in
1983 by Bayer A. G. and receiving FDA approval in 1987. Fluorine substitution at
the 6-position (common by this point) provides activity against both gramnegative as well as gram-positive bacteria. Sales were $242 million in 2008.
CO2H
N
N
HN
Ciprofloxacin
O
O
F
CO2H
F
CO2H
H
N
Me
N
N
O
Levofloxacin
N
HN
Me
N
OMe
Levofloxacin (Levaquin or Tavanic) and
Moxifloxacin (Avelox or Avelon) are fourthgeneration fluoroquinolones, generating $1,355
and $353 million in revenues in 2010,
respectively.
H
Moxifloxacin
Emmerson, A. M.; Jones, A. M. J. Antimicrob. Chemother. 2003, 51, Suppl. S1, 13-20
DNA Replication and Repair Causes Supercoiling
www.benthamscience.com/cmcaca/sample/cmcaca1-1/holden/f3-p7holden.gif
open.jorum.ac.uk/xmlui/bitstream/handle/123456789/956/Items/S377_1_013i.jpg
Quinolones Stabilize the DNA-Gyrase Covalent Intermediate
Quinolones (and coumarins) cause accumulation of the doubly-cut covalent DNA-gyrase intermediate. The nature
of the binding is uncertain (resistance hotspots on gyrA and parC subunits, may bind altered conformation of DNA)
Tyr122
Tyr122
O
OH
OH
5'
3'
A T C G A T C G A T C G A T C G
T A G C T A G C T A G C T A G C
3'
5'
5'
3'
O
A T C G A T
T A G C T A G C T A
-O
O
HO
Tyr122
F
O
CO2H
R
N
R
P
O
P
O
O-
C G A T C G A T C G
G C T A G C
3'
5'
OH
O
Tyr122
R
Pan, X.-S.; Fisher, L. M. J. Antimicrob. Agents Chemother. 1997, 41 (2), 471-474
Walsh, C. T. Antibiotics: Actions, Origins, Resistance, American Society for Microbiology Press, Washington DC, 2003 pp. 71-77
Future Directions of Antibiotics Research - Molecules
Synthetic (top) and natural-product derived (left)
antibiotics that have been launched since 2000
PA-824 is a tuberculosis
antibiotic, the processscale synthesis of which
was developed at
Princeton University
Marsini, M. A.; Reider, P. J.; Sorensen, E. J. J. Org. Chem. 2010, 75, 7479-7482; Butler, M. S.; Cooper, M. A. The Journal of Antibiotics 2011, 64, 413-425
Future Directions of Antibiotics Research - Molecules
Molecules currently in phase III clinical trials
Butler, M. S.; Cooper, M. A. The Journal of Antibiotics 2011, 64, 413-425
Future Directions of Antibiotics Research - Targets
Fatty acid biosynthesis - works well for antiseptics,
unlikely to be applicable for antibacterials (environmental
uptake).
Two-component signal transduction - unique
bacterial system to modify behavior based on external
stimuli.
O
CoA
n
Me
S
OH
n
O
CoA
S
O
Me
n
O
OH
Efflux blockers - Target specific, not general.
Quorum sensing
Oxidative stress repair
Walsh, C. T. Antibiotics: Actions, Origins, Resistance, American Society for Microbiology Press, Washington DC, 2003, chapter 15
Quorum Sensing as a Novel Antibacterial Target
Two strategies may be possible to use quorum sensing as an antibacterial strategy:
Develop molecules that turn on QS-regulated genes early, allowing
the immune response to eliminate the now-revealed intruder.
Develop antagonists that prevent QS-regulated genes from being
turned on, preventing virulence.
Bonnie Bassler
Princeton University
check out TED talk!
www.ted.com/talks/bonnie_bassler_on_how_bacteria_communicate.html http://upload.wikimedia.org/wikipedia/commons/c/cf/Quorum_sensing_diagram.png
http://www.advancedhealing.com/blog/wp-content/uploads/2009/12/Quorum_Sensing_Biofilm_Formation.gif
Quinolones Stabilize the DNA-Gyrase Covalent Intermediate
Studies non-linear effects in
systems biology
In 2007, showed that all bactericidal
antibiotics kill bacteria by a
common mechanism, oxidative
damage from hydroxyl radicals
James J. Collins
Suggests targeting RecA in order
to potentiate current antibiotic
therapies
Professor of biomedical
engineering at Boston University
RecA - involved in DNA repair
Inhibitors currently being
developed by Scott Singleton,
professor at UNC
Collins, J. J. et. al. Cell. 2007, 130, 797-810
Wigle, T. J.; Singleton, S. F. Bioorg. Med. Chem. Lett. 17 (12): 3249–53.
Nitric Oxide as Antibiotic Protection for Bacteria
NH2+
H2N
NH
HO2C
NH2
L-Lysine
NADPH + O2
Evgeny Nudler
Professor of Biochemistry
NYU Langone Medical Center
H2N
N
OH
NH
HO2C
NH2
NADPH + O2
H2N
O
NH
HO2C
NH2
L-Citrulline
N
O
Also H2S!
Nitric Oxide Synthase
Nudler, E. A. et. al. Science 2009, 325, 1380-1384; Nudler, E. A. et. al. Science 2011, 334, 986-990
http://mycrains.crainsnewyork.com/40under40/profile_images/2008/photogallery/2008NudlerLevgeny_3.jpg
Fin