Discovery of novel putative inhibitors of UDP-GlcNAc 2-epimerase as potent antibacterial agents

Article abstract of DOI:10.1021/ml4001936

We present the discovery and optimization of a novel series of inhibitors of bacterial UDP-N-acetylglucosamine 2-epimerase (called 2-epimerase in this letter). Starting from virtual screening hits, the activity of various inhibitory molecules was optimized using a combination of structure-based and rational design approaches. We successfully designed and identified a 2-epimerase inhibitor (compound 12-ES-Na, that we named Epimerox), which blocked the growth of methicillin-resistant Staphylococcus aureus (MRSA) at 3.9 μM MIC (minimum inhibitory concentration) and showed potent broad-range activity against all Gram-positive bacteria that were tested. Additionally a microplate coupled assay was performed to further confirm that the 2-epimerase inhibition of Epimerox was through a target-specific mechanism. Furthermore, Epimerox demonstrated in vivo efficacy and had a pharmacokinetic profile that is consonant with it being developed into a promising new antibiotic agent for treatment of infections caused by Gram-positive bacteria.

Full text of DOI:10.1021/ml4001936

Letter
pubs.acs.org/acsmedchemlett
Discovery of Novel Putative Inhibitors of UDP-GlcNAc 2‑Epimerase as
Potent Antibacterial Agents
Yong Xu,*,† Benjamin Brenning,† Adrianne Clifford,† David Vollmer,† Jared Bearss,†,⊥ Carissa Jones,†
Virgil McCarthy,† Chongtie Shi,† Bradley Wolfe,† Bhasker Aavula,† Steve Warner,† David J. Bearss,†,⊥
Michael V. McCullar,† Raymond Schuch,‡ Adam Pelzek,‡ Shyam S. Bhaskaran,‡ C. Erec Stebbins,§
Allan R. Goldberg,*,†,∥ Vincent A. Fischetti,*,‡ and Hariprasad Vankayalapati*,†,⊥
†Astex Pharmaceuticals, Inc. (formerly known as SuperGen, Inc.), 4140 Dublin Boulevard, Suite 200, Dublin, California 94568,
United States
‡Laboratory of Bacterial Pathogenesis and Immunology, The Rockefeller University, New York, New York 10065, United States
§Laboratory of Structural Microbiology, The Rockefeller University, New York, New York 10065, United States
S
* Supporting Information
ABSTRACT: We present the discovery and optimization of a novel
series of inhibitors of bacterial UDP-N-acetylglucosamine 2-
epimerase (called 2-epimerase in this letter). Starting from virtual
screening hits, the activity of various inhibitory molecules was
optimized using a combination of structure-based and rational
design approaches. We successfully designed and identified a 2-
epimerase inhibitor (compound 12-ES-Na, that we named
Epimerox), which blocked the growth of methicillin-resistant
Staphylococcus aureus (MRSA) at 3.9 μM MIC (minimum inhibitory
concentration) and showed potent broad-range activity against all
Gram-positive bacteria that were tested. Additionally a microplate coupled assay was performed to further confirm that the 2-
epimerase inhibition of Epimerox was through a target-specific mechanism. Furthermore, Epimerox demonstrated in vivo efficacy
and had a pharmacokinetic profile that is consonant with it being developed into a promising new antibiotic agent for treatment
of infections caused by Gram-positive bacteria.
KEYWORDS: 2-Epimerase inhibitor, antibacterial agent, Gram-positive bacteria, antibiotic-resistant pathogens, stereoisomers
catalyzes the rate-limiting step in sialic acid biosynthesis and is a
crucial regulator of cell-surface sialylation in humans.9
onhydrolyzing bacterial UDP-GlcNAc 2-epimerase (2-
Nepimerase) catalyzes the reversible conversion of UDP-
N-acetylglucosamine (UDP-GlcNAc) to UDP-N-acetyl-man-
nosamine (UDP-ManNAc).1,2 The catalytic activity of 2-
epimerases produces an activated form of ManNac residues
for use in the biosynthesis of a variety of cell surface
polysaccharides and the enterobacterial common antigen
(ECA), a surface-associated glycolipid common to all members
of the Enterobacteriaceae family (Gram-negative bacteria).3 In
Gram-positive bacteria such as Staphylococcus aureus and
Bacillus anthracis, the importance of 2-epimerase in the
biosynthesis of polysaccharides is highlighted by the presence
of at least two functionally redundant copies of this enzyme.4,5
The structural homology of 2-epimerase to phosphoglycosyl
transferases supports the mechanism that the 2-epimerase-
catalyzed elimination and readdition of UDP to the glycal
intermediate may proceed through a transition state with
significant oxocarbenium ion-like character.6 This bacterial 2-
epimerase is related to the bifunctional mammalian 2-
epimerase/ManNAc kinase, a hydrolyzing enzyme that converts
UDP-GlcNAc into UDP and ManNAc and phosphorylates the
latter into ManNAc 6-phosphate.7,8 The mammalian enzyme
Bacterial 2-epimerase was characterized as a homodimer in
the late 70s and was shown not to require any exogenous
cofactors or metal ions for activity. It also was shown that the
enzyme was tightly regulated by its own substrate UDP-
GlcNAc. No significant UDP-ManNAc epimerization is
observed in the absence of substrate UDP-GlcNAc.2,10,11
However, only when trace amounts of UDP-GlcNAc are
added does the reaction proceed to equilibrium, thus indicating
that UDP-GlcNAc is required for the enzyme to acquire a
catalytically competent conformation.
Recently, some of us disclosed the structure of B. anthracis 2-
epimerase in the presence of UDP-GlcNAc, which was
observed to bind to both the active site of 2-epimerase and
to its allosteric site. The structure of B. anthracis 2-epimerase is
very similar to the previously determined structure of the
homologous E. coli 2-epimerase in complex with UDP (Protein
Data Bank (PDB) ID 1F6D)12 or with UDP-GalNAc (PDB ID
Received: May 18, 2013
Accepted: October 19, 2013
© XXXX American Chemical Society
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1VGV)13 and the Bacillus subtilis enzyme without substrate
(PDB ID 1O6C).13 This was the first time that UDP-GlcNAc
was shown to bind both to the allosteric and active site of 2-
epimerase. Sequence alignments of 2-epimerases from several
bacterial species show that the bacterial UDP-GlcNAc-binding
site is conserved and probably unique to the nonhydrolyzing
bacterial 2-epimerases. In addition, epimerase gene knockout
experiments demonstrated that deletion of one copy of the 2-
epimerase gene in B. anthracis (BA5509) had impaired growth
compared with the wild-type strains.17 The conservation of the
allosteric site residues in the nonhydrolyzing bacterial 2-
epimerases (Figure 1) indicates that the allosteric regulatory
Scheme 1. Design Strategy for 2-Epimerase Inhibitors
linked with polar head groups through an ethylene double
bond. The lead compound 1c was designed by combining the
fragments within the dotted area in hit compounds 1a and 1b.
Subsequently, the replacement of sulfur in a rhodanine class18
of thioxothiazolidine 1c generated the thioxoimidazolidine lead
compound 1d.
All of the final compounds were prepared using the
condensation reaction (Knoevenagel reaction) of substituted
thiohydantoins with corresponding aldehydes or ketones.19 The
choice of reaction conditions was crucial for the condensation
reaction. The most commonly used basic condensation
conditions were not useful for the preparation of the targeted
molecules because the substituted thiohydantoin was labile
under basic conditions and elevated temperatures. Therefore,
we developed two kinds of reaction conditions, which were
suitable for substituted thiohydantoins condensation reactions
(Scheme 2). The starting material thiohydantoin was prepared
Figure 1. UDP-N-acetylglucosamine 2-epimerase-catalyzed reactions.
mechanism, which involves direct interaction between one
substrate molecule in the active site and another in the
allosteric site, is used exclusively by this class of bacterial
enzymes, thus providing a selective way of targeting them,
particularly in the case of B. anthracis, for the development of
antibacterial agents.
a
Scheme 2. General Synthetic Route
There are some reported inhibitors of 2-epimerases, but most
of them are amino sugars, which are mimics or modified
GlcNAc/UDP-GlcNAc and strongly bind to the active site of 2-
epimerases.14−16 Since their structures have phosphate and
amino sugar moieties, they are not drug-like and have poor
physicochemical properties in general and only can be used as
laboratory tools for inhibition of 2-epimerases.
We recently disclosed the identification of a promising 2-
epimerase inhibitor (12-ES-Na or Epimerox) with reduced
resistance potential.17 Herein, we report in greater depth the
development, optimization, and synthesis of Epimerox and
several related novel 2-epimerase inhibitors with potent activity
against Gram-positive bacteria.17 We initiated our hit-finding
efforts by using the 2-epimerase crystal structure as a model for
the docking of a large virtual library (∼2 million compounds),
composed of in-house and commercially available small
molecules, to generate a subset of hits based on calculated
binding energies and scores. These hits then were evaluated
using a number of in silico physicochemical and ADMET
prediction algorithms to determine the degree to which they
possessed drug-like properties.22,23 Selected hit compounds
(∼100 compounds selected from the 2 million compounds
virtual screening libraries) were initially screened using a
biochemical enzyme-based assay and a bacterial growth
inhibition assay. At a concentration of 30 μM, numerous lead
candidates were identified to inhibit bacterial growth by over
50% compared with untreated controls. These lead candidates
served as starting points for lead optimization (Scheme 1).
Specifically, as shown in Scheme 1, hit compounds 1a and 1b
had similar structures, consisting of hydrophobic moieties
a
Reagents and conditions: (a) Stille coupling; (b) Suzuki coupling; (c)
β-alanine, AcOH, 80 °C, 16 h, 54%; (d) THF, reflux 16 h, 66%.
using the cyclization reaction of thiocarbonyl agent 1,1′-
thiocarbonyldiimidazole with dipeptide Gly-DL-Phe.20 The first
method employed acetic anhydride as a promoter, and the
condensation reaction proceeded readily at 80 °C for 2 h.21
The second method utilized β-alanine, a neutral amino acid, as
catalyst, and the condensation reaction provided a good yield of
product in 30 min under microwave irradiation.22 During the
synthesis of this type of compound, we observed that inorganic
bases, such as Na2CO3 and NaHCO3, decomposed either the
hydantoin starting materials or products completely at elevated
temperature, and no desired product could be detected. The
starting material 5-phenyl furanaldehydes were prepared using
either Suzuki coupling reactions from the corresponding
boronic acids or Stille coupling reactions from stannyl reagents,
depending on the availability of the starting materials.
B
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Considering the potential poor permeability of carboxylic
acid compounds, we investigated the bioisostere of carboxylic
acid to optimize the lead compound’s physicochemical
properties and potency (Scheme 3). The bioisosteric
membered ring linker. As shown in Table 2, the furan-linked
dihalogen compounds have significantly improved activity in
comparison with the corresponding monohalogen substituted
compounds. In contrast, the thiophene-linked compounds have
decreased activity relative to the corresponding monohalogen
substituted compounds.
Scheme 3. Synthesis of Bioisosteres of Carboxylic Acid
To improve compound’s potency and physicochemical
properties, we investigated several commonly used bioisosteres
of carboxylic acid, including amide, ethyl ester, cyano amide,
methanesulfonylamide, and trifluoro-methanesulfonylamide.
We synthesized the above-mentioned bioisosteres of carboxylic
acid and found that only the ethyl ester compound aborted the
activity (Table 3). Trifluoromethanesulfonylamide exhibited
the best activity and showed activity similar to that of the
parent compound. As shown in compounds 17 and 23, the
replacement of phenyl with methyl reduced potency signifi-
cantly and further indicated that the ππ-stacking interaction of
phenyl is required for the inhibition potency.
Considering that compound 12 had the most potent
inhibitory activity, we also investigated the effect of E/Z
configuration of the double bond and R/S chirality of the
carboxylic acid on growth inhibition activity. NMR and HPLC
analysis of compound 12 showed that the major isomer is the E
isomer with 90% ratio. The E-isomer was successfully separated
by recrystallization in DCM-CH3OH cosolvent. However, the
separation of Z-isomer by recrystallization failed after various
conditions and solvents were tried (Scheme 4). Therefore, the
Z-isomer was isolated using preparative HPLC. After obtaining
both -E and -Z isomers of compound 12, we evaluated their
growth inhibitory activity and found no significant difference
between these isomers. Each of the R/E and S/E isomers were
obtained by beginning with enantiomerically pure starting
material Gly-D-Phe and Gly-L-Phe, respectively. However, all
four isomers showed equivalent inhibitory activity (6.8 μM
MIC) on strains of S. aureus 13709 and B. subtilis 19659.
Furthermore, we found that the sodium salt of compound 12
(12-ES) (Scheme 4) had equivalent growth inhibitory potency
but with much better aqueous solubility, a feature that might
expedite formulation and in vivo studies. We also evaluated the
chemical stability of compound 12-ES-Na and found that it was
very stable. We did not observe any isomerization or
compounds of carboxylic acid were prepared by coupling
carboxylic acid with the corresponding amine, alcohol, or
sulfonamide, and the reaction was promoted by HBTU in the
presence of DIPEA. Ammonium chloride instead of ammonia
was utilized as an amination reagent to prepare the primary
amide compound. The condensation reaction of methanesul-
fonyl amide and trifluoromethanesulfonyl amide with acid also
afforded good yields of N-sulfonyl amide products under the
same reaction conditions.
First, we investigated the effect of substituents on the
terminal phenyl ring. In the following order, -OCH3, -H, -F,
-Cl, -Br, -I, and -OCF3, the electron-withdrawing group
increased the potency and the electron-donating group
decreased the potency, suggesting that the electron-with-
drawing group is beneficial for binding to 2-epimerase (Table
1).
The bromide group exhibited optimal potency. Iodo and
trifluoromethoxyl groups exhibited slightly weaker activity
compared with the bromide compound. The furan and
thiophene linkers showed similar activity and indicated that
both an oxygen and sulfur atom at this position could be
tolerated well by 2-epimerase.
Since the electron-withdrawing group at the terminal phenyl
group enhanced the potency, we also explored dihalogen
substituted compounds. However, we found that the potency of
dihalogen substituted compounds was related to the five-
a
Table 1. Compound Structure and Antibiotic Activity against B. anthracis and MRSA
b
b
B.anthracis inhibition percentage
S. aureus (MRSA) inhibition percentage
compd
R1
R2
X
30 μm
10 μm
3 μm
30 μm
10 μm
3 μm
1
2
3
4
5
6
7
8
9
10
-H
-H
-H
-H
-H
-H
-Cl
-H
-H
-H
-OCH3
-F
S
100
100
100
100
20
0
0
20
50
90
90
10
90
10
90
90
100
10
20
0
0
S
10
0
20
0
-Cl
S
100
100
10
0
-Br
S
80
0
90
10
20
0
20
0
-H
O
O
O
O
O
O
-Cl
100
90
70
0
10
0
-H
0
10
70
50
10
-Br
100
100
100
100
100
100
90
90
10
10
0
-I
-OCF3
0
a
b
B. anthracis Sterne strain. Each value is the mean of at least three experiments, and the standard deviation is less than 10% of the mean.
C
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Table 2. Compound Structure and Antibiotic Activity against B. anthracis and MRSA
Letter
a
b
b
B.anthracis inhibition percentage
S. aureus (MRSA) inhibition percentage
compd
R1
R2
-Cl
R3
X
30 μm
10 μm
3 μm
30 μm
10 μm
3 μm
11
12
13
14
15
16
-Cl
-Cl
-Cl
-Cl
-Cl
-Cl
-H
-H
-H
-H
-Cl
-H
S
90
110
110
10
0
40
100
0
10
90
10
100
10
10
10
20
-Cl
O
S
110
90
110
20
100
0
-Br
-Br
O
O
O
100
100
100
100
0
100
90
80
20
0
-H
-OCH3
30
0
10
a
b
B. anthracis Sterne strain. Each value is the mean of at least three experiments, and the standard deviation is less than 10% of the mean.
a
Table 3. Compound Structure and Antibiotic Activity against B. anthracis and MRSA
b
b
B.anthracis inhibition percentage
S. aureus (MRSA) inhibition percentage
compd
R4
R5
30 μm
10 μm
3 μm
30 μm
10 μm
3 μm
12
17
18
19
20
21
22
23
-COOH
-Ph
110
90
110
100
90
110
0
100
90
60
0
90
0
20
0
-COOH
-CH3
-Ph
-CONH2
-CO2Et
90
20
30
0
0
-Ph
0
50
-NHCN
-Ph
100
90
100
100
100
0
0
100
60
90
0
0
0
0
0
0
-NHSO2CH3
-NHSO2CF3
-Ph
40
70
10
30
80
0
-Ph
100
20
-NHSO2CH3
-CH3
a
b
B. anthracis Sterne strain. Each value is the mean of at least three experiments, and the standard deviation is less than 10% of the mean.
epimerase as shown in Figure 2. Hydrogen binding interaction
with the Arg211 and proximity to the Arg210 residue involved
in allosteric regulation is the key for the activities of compound
Scheme 4. Optimized Synthetic Route to Compound 12-ES-
Na
a
a
Reagents and conditions: (a) THF, RT, 16 h, 43%; (b) β-alanine,
AcOH, 80 °C, 16 h, 54%; (c) DCM, CH3OH, hexane, recrystalliza-
tion; (d) Na2CO3, DCM, CH3OH, and DCM, recrystallization, 83%.
decomposition for compound 12-ES-Na at pH = 10 aqueous
solution after 3 days. No isomerization was detected by HPLC
or NMR.
Beginning with a 2 million compound virtual screening
library,23,24 hit-to-lead optimization and docking experiments
were performed using a crystal structure of 2-epimerase (PDB
ID 3BEO) in complex with Epimerox17 suggesting that
compound 12-ES bound in the allosteric binding site of 2-
Figure 2. Docking model of the complex formed between compound
12-ES and the 2-epimerase crystal structure model (PDB ID 1F6D) of
the allosteric binding site. The critical residues involved in H-bonding
interaction were shown as solid yellow dashed lines.
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Table 4. Spectrum of Antibacterial Activity for Compound 12-ES-Na
a
a
strain
Gram
MIC μM
strain
Gram
MIC μM
P. aeruginosa
S. aureus
negative
positive
negative
negative
positive
positive
negative
negative
positive
negative
negative
>25
3.91
>25
>25
>25
3.91
>25
>25
7.8
S. aureus 6538
positive
positive
positive
positive
positive
positive
positive
positive
positive
positive
positive
7.8
7.8
2.0
3.9
3.9
3.9
3.9
15.6
15.6
7.8
7.8
S. aureus 13709
S. epidermidis 13518
S.pyogenes 19615
S. agalacatiae 12386
S. pneumoniae 6301
S. mutans 25175
E. faecalis 19433
E. faecium 6569
B. subtilis 19659
S. equi 6939
S. enterica
E. coli
C. albicans
S. epidermidis
S. marcescens
S. sonnei
B. atrophaeus
A. baumannii
P. mirabilis
>25
>25
a
MICs were determined in triplicate on three different days using a broth microdilution method; no variation was observed in MIC values.
Table 5. Pharmacokinetic Properties of Compound 12-ES-Na on CD-1 Female Mice
group dose (mg/kg) tmax (h) Cmax (ng/mL) half-life (h) VZ (mL/kg) Cl (ML/h/kg) AUC (ng.h/mL) time (h) above MIC (2000 ng/mL)
1
2
3
4
25
0.08
0.5
68000
2.4
2.3
2.2
3.4
500
340
180
240
140
100
55
170000
480000
1800000
1050000
10.6
14.6
19.4
18.3
50
140000
490000
320000
100
0.08
3.08
50 (BID)
47
12-ES. In designing thioxothiazolidine replacements, we chose
the allosteric binding thioxothiazolidine core to thioxoimida-
zolidine as well as the substitution of electron-withdrawing
groups at the 2-aryl that oriented favorably with the histidine
His242 and His209 through charge−charge contacts. Addi-
tionally, our lead optimization efforts toward compound 12-ES
established the importance of occupying the vector adjacent to
the allosteric site; the phenyl propionate πιπι-stacking
interactions with Tyr134 for overall stability and 2-epimerase
activity.
by testing a panel of both Gram-positive and Gram-negative
bacterial strains. Table 4 indicates that the sodium salt, 12-ES-
Na, had good activity against the panel of Gram-positive
bacteria, but not significant potency against Gram-negative
strains.
The compound 12-ES-Na showed the most desirable
potency profile and was further evaluated to assess
pharmacokinetic properties in mice. The objective of the
pharmacokinetic study was to assess the exposure of CD-1
female mice to 12-ES-Na when the test compound was
administered intraperitoneally (i.p). Mouse pharmaco-kinetic
studies showed a strong dose response with reasonably linear
kinetics with increasing dose. Lead compound 12-ES-Na, had a
reasonable rodent PK profile with a half-life of 2−3 h and a
clearance of ∼100 mL/h/kg. The AUC was more than 200-fold
the MIC, and time of concentration above MIC was more than
10 h following a single dose (Table 5). There was no mortality
and no significant clinical observations were noted when the
dosage was below 100 mg/kg.
The in vivo efficacy for 12-ES-Na was demonstrated in
survival studies following administration of B. anthracis
(Sterne). Compound 12-ES-Na was evaluated for its ability
to prevent mortality in mice infected with a lethal dose of B.
anthracis (Sterne). Compound 12-ES-Na was dissolved
completely in propylene glycol (customarily used and approved
by the FDA for use in injectable) and then could be diluted
further in PBS, thereby allowing the undertaking of additional
preclinical trials in mice. A full description of this experiment
was published and it showed that the epimerase inhibitor 12-
ES-Na can effectively block Bacillus anthracis infection in
mice.17
The incorporation of this thioxoimidazolidine appeared to
satisfy structural requirements for 2-epimerase binding over the
promiscuous 2-thioxothiazolidin moiety and was one of the
major considerations in the design of compound 12 and its
analogues. The 2-thioxoimidazolidine−NH participated in
hydrogen bonding interaction with the backbone carbonyl
oxygen of Arg210. Lastly, the carboxylic acid moiety occupied
Arg211 region of the active site and involved in strong
hydrogen bonding interactions with −NH of Arg211. Further
we modeled the compound 12 R/E and S/E isomers and
observed its effect within the allosteric site of the 2-epimerase
crystal structure. The position and orientations of each of the
isomers revealed that there is no isomeric effect on binding of
compound 12 or its thioxoimidazolidine series of compounds
and further supported the conserved H-bonding interaction
with Arg211 and synergy with the growth inhibitory activities.
This has provided a fixable substitution vector to modulate
physicochemical and ADME properties such as pKa23 and for
the preparation few bioisosteres of carboxylic acid, such as
−NHSO2CH3, NHSO2CF3, and NHCN groups were explored
because of their favorable physicochemical properties and their
synthetic tractability presented in Scheme 4 and Table 3.
Inhibitory activity of compound 12-ES-Na against B.
anthracis UDP-GlcNAc 2-epimerase was tested in a previously
described coupled assay that employs UDP-ManNAc dehydro-
genase10 giving a Ki of 82 μM under physiological conditions
(Figure S1, Supporting Information). On the basis of the in
vitro potency of compound 12-ES-Na (or Epimerox) on B.
anthracis (Sterne) and MRSA, we further evaluated 12-ES-Na
In conclusion, we developed a series of putative inhibitors of
the bacterial enzyme 2-epimerase. All of these 2-epimerase
inhibitor compounds blocked the growth of MRSA at low μM
MIC as well as growth of all other tested Gram-positive
bacterial strains. On the basis of its PK and efficacy profile,
compound 12-ES-Na (Epimerox) appears to be a promising
new antibacterial agent for the treatment of infections caused
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ASSOCIATED CONTENT
* Supporting Information
Full experimental procedures and characterization for all
compounds. This material is available free of charge via the
Internet at http://pubs.acs.org.
■
S
AUTHOR INFORMATION
Corresponding Authors
*(H.V.) E-mail: hari@hci.utah.edu.
*(V.A.F.) E-mail: vaf@rockefeller.edu.
*(A.R.G.) E-mail: agoldberg@avacynpharm.com.
*(Y.X.) E-mail: yxu22@hotmail.com.
■
(12) Campbell, R. E.; Mosimann, S. C.; Tanner, M. E.; Strynadka, N.
C. J. The structure of UDP-N-acetylglucosamine 2-epimerase reveals
homology to phosphoglycosyl transferases. Biochemistry 2000, 39,
14993−15001.
Present Addresses
∥Avacyn Pharmaceuticals, Inc., Teaneck, New Jersey 07666,
United States.
⊥Division of Oncology of School of Medicine and Center for
Investigational Therapeutics at Huntsman Cancer Institute,
University of Utah, 2000 Circle of Hope, Salt Lake City, Utah
84112, United States.
(13) Badger, J.; Sauder, J. M.; Adams, J. M.; Antonysamy, S.; Bain, K.;
Bergseid, M. G.; Buchanan, S. G.; Buchanan, M. D.; Batiyenko, Y.;
Christopher, J. A.; Emtage, S.; Eroshkina, A.; Feil, I.; Furlong, E. B.;
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Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported in part by grants 1U19AI056510,
AI057472, and 2U54AI057153 to Dr. Vincent A. Fischetti from
the National Institute of Allergy and Infectious Disease and
early discovery and development support from Astex
Pharmaceuticals.
ABBREVIATIONS
■
UDP, uridine diphosphate; MRSA, methicillin-resistant Staph-
ylococcus aureus; MIC, minimum inhibitory concentration;
ADMET, absorption, distribution, metabolism, excretion, and
toxicity; HBTU, N,N,N′,N′-tetramethyl-O-(1H-benzotriazol-1-
yl)uronium hexafluorophosphate; DIPEA, N,N-diisopropyle-
thylamine; AUC, area under the concentration curve; DCM,
dichloromethylene; PK, pharmacokinetic
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