Synthesis and evaluation of quinazolines as inhibitors of the bacterial cell division protein FtsZ

Article abstract of DOI:10.1021/ml500497s

The bacterial cell division protein FtsZ is one of many potential targets for the development of novel antibiotics. Recently, zantrin Z3 was shown to be a cross-species inhibitor of FtsZ; however, its specific interactions with the protein are still unknown. Herein we report the synthesis of analogues that contain a more tractable core structure and an analogue with single-digit micromolar inhibition of FtsZs GTPase activity, which represents the most potent inhibitor of Escherichia coli FtsZ reported to date. In addition, the zantrin Z3 core has been converted to two potential photo-cross-linking reagents for proteomic studies that could shed light on the molecular interactions between FtsZ and molecules related to zantrin Z3.

Full text of DOI:10.1021/ml500497s

Letter
pubs.acs.org/acsmedchemlett
Synthesis and Evaluation of Quinazolines as Inhibitors of the
Bacterial Cell Division Protein FtsZ
Gabriella M. Nepomuceno, Katie M. Chan, Valerie Huynh, Kevin S. Martin, Jared T. Moore,
Terrence E. O’Brien, Luiz A. E. Pollo, Francisco J. Sarabia, Clarissa Tadeus, Zi Yao, David E. Anderson,
James B. Ames, and Jared T. Shaw*
University of California, Davis, One Shields Avenue, Davis, California 95616, United States
S
* Supporting Information
ABSTRACT: The bacterial cell division protein FtsZ is one of many potential targets for
the development of novel antibiotics. Recently, zantrin Z3 was shown to be a cross-species
inhibitor of FtsZ; however, its specific interactions with the protein are still unknown.
Herein we report the synthesis of analogues that contain a more tractable core structure
and an analogue with single-digit micromolar inhibition of FtsZ’s GTPase activity, which
represents the most potent inhibitor of Escherichia coli FtsZ reported to date. In addition,
the zantrin Z3 core has been converted to two potential photo-cross-linking reagents for
proteomic studies that could shed light on the molecular interactions between FtsZ and
molecules related to zantrin Z3.
KEYWORDS: FtsZ, zantrin Z3, SAR, bacterial cell division
acterial infections are increasingly difficult to combat as
available antibiotics become less effective and bacteria
B
evolve resistance to current therapies.1 With more than two
million illnesses annually attributed to resistant bacteria, and
the diminishing timeline between drug implementation and
resistance, we face a dire need for new antibiotics.2 Oftentimes,
available antibiotics are modified to prolong their use for a
known target,3,4 but a new protein or pathway offers an area of
therapeutic research that has no known resistance. The
bacterial divisome is a complex set of biochemical machinery
that contains many proteins whose shape and function remain
somewhat elusive. These proteins offer new areas of antibiotic
study.5,6 Temperature-sensitive filamenting protein Z (FtsZ) is
highly conserved among bacterial species and is essential for
cell division. Therefore, FtsZ is an exciting target for developing
a broad spectrum antibiotic.7 The homologous eukaryotic
protein, tubulin, has been successfully targeted by small
molecules such as taxol,8,9 epothilone,10 and many others to
halt the division of cancer cells.11−13 By analogy, an inhibitor of
FtsZ could halt bacterial cell division and form the basis of a
novel antibiotic.
Figure 1. Small molecule modulators of FtsZ. (A) Activator
PC190723.19,23 (B) Zantrin Z3 (1) and its more potent analogue,
dimethyl ZZ3 (2).19 Three regions are identified in ZZ3 as
synthetically accessible for further modification.
structural data is available for inhibitor-FtsZ interactions even
though many crystal structures of the protein itself have been
published. Despite only modest inhibitory activity in an
absolute sense, zantrin Z3 remains the best known inhibitor
of FtsZ’s GTPase activity. Unlike tubulin, for which inhibitors
act at nano- and picomolar concentrations, all known FtsZ
inhibitors act in the micromolar range!
Preliminary modifications of 1 led to the discovery of 2,
which is twice as potent as its parent compound19 and provided
a benchmark for further structure−activity studies. ZZ3 has
three regions where modifications are synthetically accessible.
Substituted anthranilic acids were used to explore the binding
interactions of the benzoquinazoline core by replacing the fused
There are many reported inhibitors of FtsZ that have shown
the ability to cause filamentation in bacteria.14−18 However,
certain inhibitors were recently shown to have irreproducible
activity or showed the filamentation phenotype but were not
specific to FtsZ inhibition.19,20 Two compounds were found to
directly modulate FtsZ: PC190723 and zantrin Z3 (Figure 1).
PC190723 has been shown to activate the GTPase activity of
Staphylococcus aureus FtsZ.21−23 On the other hand, zantrin
Z324 (ZZ3, 1) was the only compound to reliably inhibit
Bacillus subtilis FtsZ (BsFtsZ) and Escherichia coli FtsZ
(EcFtsZ). Although ZZ3 reliably inhibits FtsZ, its specific
molecular interactions are unknown. Furthermore, very little
Received: December 2, 2014
Accepted: January 7, 2015
© XXXX American Chemical Society
A
DOI: 10.1021/ml500497s
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ACS Medicinal Chemistry Letters
Letter
benzene ring with functional groups of varied sterics and
electronics (Figure 1, region 1), while the styryl component
was replaced by functional groups thought to be isosteric in
region 2. Continued exploration of the amine fragment was
achieved through SNAr reactions. Further modifications to aryl
halide analogues allowed for the creation of potential photo-
cross-linkers to be used as small molecule probes for binding
site identification of ZZ3 derivatives in FtsZ.
6-position (R2) exhibited the best inhibitory activity, leading to
investigation of larger substituents at this position. Palladium-
catalyzed cross-coupling reactions of aryl bromide 5f afforded
5h−k in acceptable yields.27 Cyclohexenylboronic acid was
similarly coupled in order to test a nonaromatic substituent
(5l). Diminished reactivity of the alkenyl boronic ester required
use of the 6-iodo precursor (5g) to boost the yield to an
isolatable amount. None of the subsequent (5h−k) compounds
showed better inhibitory activity compared to the 6-methyl
analogue.
With the 6-position fixed as methyl, alteration and
replacement of the styryl side chain (region 2) were examined.
Compounds 8a−d were synthesized in good yield as previously
described in Scheme 1. 2-Amino-5-methylbenzoic acid was
cyclized with potassium cyanate followed by sodium hydroxide
and hydrochloric acid to form quinazolinedione 6.28 Chlorina-
tion and amination yielded 7 in good yield.19 Boc-protection of
7,29 subsequent displacement of the chloride, and deprotection
with trifluoroacetic acid resulted in benzylamine derivatives 8e
and 8f (Figure 2).30 Under the same deprotection conditions,
Early changes to 1 focused on reducing its size in hopes of
finding a compound with greater “ligand efficiency.” This term
has emerged to describe the level of activity on a per-atom (or
per-Dalton) basis, thus avoiding a tendency to achieve potency
at the expense of drug-likeness.25 The 4-quinazalone core was
synthesized in one step from commercially available substituted
anthranilic acids (3a−g), subjected to acid-mediated aldol
condensation conditions and subsequently chlorinated with
phosphorus(V) oxychloride to give quinazolines 4a−g in
moderate yields. Amination with N,N-dimethylethylenediamine
and Hunig’s base yielded 5a−g in high yields (Scheme 1).19
̈
a
Scheme 1. Synthesis of Dimethyl ZZ3 Analogues
a
Reagents and conditions: (a) R2-B(OH)2, dppf·PdCl2(II), CH3CN/
H2O (1:1), μW, 140 °C, 45 min, 12-48% yield. Compounds 5k−l were
synthesized similarly from 5g in 24 and 20% yield, respectively.
Table 1. Region 1 Analogues of 2 and Related IC50.
a
Figure 2. Synthesis and IC50 of compounds 8a−m. (A) Compounds
8a−d were made in 4 steps as previously described in Scheme 1.
Compounds 8e−g: (1) Boc2O, DMAP, Et3N, THF, 25 °C, 24 h, 76%;
(2) 4-RBnNH2, DMSO, 90 °C, 16 h, 43−64%; (3) TFA, CH2Cl2, 0 °C
b
to rt, 24 h, 100%. Upon subjection to TFA, the 4-methoxybenzyl-
amine derivative (not shown) yielded 8g in 40% yield. (b)
Compounds 8h−l were synthesized by Suzuki couplings as described
in Scheme 1 in 24−65%. (B) Region 2 analogues and their
corresponding IC50.
entry
R1
R2
R3
IC50 (μM)
5a
5b
5c
5d
5e
5f
H
H
H
H
H
>128
>128
24
CH3
H
H
CH3
H
the 4-methoxybenzylamine derivative (not shown) yielded
primary amine 8g. Compound 7 was also subjected to Suzuki
cross-couplings with dppf·PdCl2(II) to give biaryl derivatives
8h−l.27 Unfortunately, none of the changes in region 2
demonstrated better activity than 1 or 2.
The observation that major alterations to the styryl unit
diminished activity suggested that an isosteric replacement was
required. Amides, often considered isosteric to alkenes,
required incorporation of a pendant carboxyl group. Fisher
esterification of 2-amino-5-methylbenzoic acid yielded amino
ester 9.31 Cyclization with the ethyl variant of Mander’s
reagent32 followed by chlorination yielded 10, which was
subsequently aminated to provide esters 11a and 11b (Scheme
2). In order to directly compare the styryl moiety to an isostere,
H
CF3
CH3O
H
>128
100
30
H
CH3O
H
Br
5g
5h
5i
H
I
H
95
H
phenyl
H
28
H
4-pyridyl
2-naphthyl
2-thiophenyl
cyclohexenyl
H
30
5j
H
H
58
5k
51
H
H
>128
49
H
H
Compounds 5a−g were then subjected to an enzyme-
coupled GTPase assay to measure their half-maximal inhibition
concentration (IC50).26 Methyl and bromo substitution at the
B
DOI: 10.1021/ml500497s
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ACS Medicinal Chemistry Letters
Letter
a
Scheme 2. Synthesis and IC50 of 11a−d
Table 2. Region 3 Analogues of 5c and 2 and Related IC50.
a
Reagents and conditions: (a) 11c (1) n-BuLi, 4-ClPhNH2, DMPU
THF, 0 °C, 20 min; 11a, THF, rt to 80 °C, 1 h; 10%. (2) HCl/
dioxane, 40 °C, 3 h, 88%. (b) 11b, i-PrMgCl·LiCl, THF, rt, 12 h.
11a was converted to a benzamide analogue. The dimethyl-
amine version of the 4-chlorobenzamide (not shown) proved
difficult to isolate cleanly; fortunately, concurrent exploration of
the amine fragment yielded a Boc-protected amine would reveal
an ammonium salt with better inhibition than the correspond-
ing dimethylamine (Table 2). Ester 11a was converted to
benzamide 11c in 88% yield after deprotection. 4-Chloroben-
zylamide 11d was synthesized in 25% yield providing a less
rotationally hindered analogue to parallel the styrene. Neither
amide modification improved inhibitory activity relative to 1
and 2 despite incorporating the ammonium side chain in 11c.
The final modifications examined involved altering or
replacing the amino ethyl side chain (region 3). Compound
4c was subjected to SNAr reactions with nucleophiles
containing single-point changes to generate analogues with
different side chains at the 4-position of the quinazoline ring.
Deprotection of 13b with TFA gave 13c in quantitative yield.
These three compounds (13a−c, Scheme 3) suggested a
positively charged fragment is necessary for inhibition, although
the ammonium substrate (13c) only showed marginal activity.
Upon comparing the most potent inhibitors in the 2- and 3-ring
systems (5c and 2, respectively), we prepared several other
substrates (Table 2, 13d−j) by cyclizing 2-naphthoic acid and
subsequently chlorinating as described in Scheme 1. Sub-
stitution with 2-(dimethylamino)ethanol resulted in 13d, which
showed moderate inhibition. Further substitutions with various
amines gave 13e−j. Deprotection of 13i with TFA resulted in
13l.33 Further modification through acetylation34 of 13l to 13m
resulted in complete loss of inhibitory activity. While a
positively charged “tail” retained some inhibitory activity
(13d and 13g), the quaternary ammonium side chain of
compound 13k, which was formed by alkylation with CH3I,35 is
quite bulky and likely disrupts important binding interactions.
Conversely, the benzoquinazoline ammonium substrate (13l) is
now the first substrate to demonstrate activity in the single-digit
micromolar range.
a
Scheme 3. Synthesis of Region 3 Analogues
In addition to optimizing inhibitory activity through
structure−activity relationships (SAR), knowledge of modifica-
tions that are tolerated has provided the structural basis for the
design of photoaffinity reagents. A survey of potential cross-
linkers revealed photoactivatable azides, benzophenones and
diazirines, which upon irradiation could covalently link a ZZ3
derivative to FtsZ. Digestion and mass spectrometry analysis
would lead to proteomic information that could be used to
identify the binding-site of ZZ3. Benzophenones are historically
reliable cross-linkers that are easily synthesized but run the risk
of reduced binding due to the size of the phenyl ketone. The
preceding observations suggested the phenylketone could be
installed at the 6-position of the quinazoline core. A
carbonylative Stille coupling with tributylphenylstannane and
carbon monoxide readily converted aryl iodide 5g to the
corresponding benzophenone derivative (14, Figure 3) in 67%
isolated yield. Unfortunately, this photo-cross-linker showed a
loss of inhibitory activity with an IC50 of 85 μM. We then
turned our attention to installing an aryl azide in region 3 as it
is less sterically demanding and electronically similar to an aryl
chloride. Aryl iodide 15, which was synthesized from 2-
aminonaphthoic acid in 4 steps as described in Scheme 1, was
a
b
Reagents and conditions: 13a−b were synthesized from 4c in 41%
yield each. c13d−j were synthesized similarly from 12 in 54-82% yield.
(a) Compounds 13c and 13l: TFA, CH2Cl2, 0 °C to rt, 3 h, 80-100%.
(b) Compound 13k: CH3I, CH3OH, rt, 12 h, 21%. (c) Compound
13m: Ac2O, Et3N, CH2Cl2, rt, 45 min, 31%.
C
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ACS Medicinal Chemistry Letters
Letter
Arnold and Mabel Beckman Foundation. This research was
partially supported by an industry/campus supported fellow-
ship to J.T.M. under the Training Program in Biomolecular
Technology (T32-GM008799) at the University of California,
Davis.
Notes
The authors declare no competing financial interest.
ABBREVIATIONS
■
FtsZ, temperature sensitive filamenting protein Z; ZZ3, zantrin
Z3; BsFtsZ, Bacillus subtilis FtsZ; EcFtsZ, Escherichia coli FtsZ;
AcOH, acetic acid; N,N-DMEDA, N,N-dimethylethylaminedi-
amine; DIPEA, diisopropylethylamine; dppf, 1,1′-bis-
(diphenylphosphino)ferrocene; μW, microwave; IC50, half-
maximal inhibition concentration; μM, micromolar; t-Bu, tert-
butyl; Ph, phenyl; Bn, benzyl; Boc, tert-butyl carbamate; TFA,
trifluoroacetic acid; n-BuLi, n-butyllithium; DMPU, N,N′-
dimethylpropyleneurea; Ac2O, acetic anhydride; DMF, dime-
thylformamide; EtOH, ethanol; THF, tetrahydrofuran; N,N′-
DMEDA, N,N′-dimethylethylaminediamine
Figure 3. Synthesis and IC50 of photo-cross-linkers. (A) Benzophe-
none cross-linker 14. (B) Azide cross-linker 16.
subjected to copper-mediated azidonation36 providing 16 in
good yield. Compound 16 demonstrated similar inhibitory
activity to 2, which is important for ensuring specific site
selection during photoactivation.
This SAR study has revealed three important features. First,
the benzo[g]quinazoline of 1 and 2 can be replaced by the
smaller quinazoline, provided that a small substituent is
maintained at position 6 (e.g., 5c, Table 1). Second, a smaller,
and yet still positively charged, amino side chain provides the
best activity to date (e.g., 13l, Table 2). Finally, the 4-
chlorostyryl fragment remains necessary for inhibitory activity;
replacement with several different isosteres obliterates inhib-
itory activity. Although the IC50s of the best compounds in this
series are still in the micromolar range, this activity is
comparable to the best inhibitors of FtsZ reported so far.
More dramatic changes to the core are difficult to predict or
design without direct structural data. Installing a reactive
functional group for cross-linking studies may determine the
binding site of this unique inhibitor. Although preliminary
competition studies suggest zantrin Z3 does not bind to the
GTP pocket (see Supporting Information), further illumination
will require successful cross-linking studies or crystallography of
the inhibitor-FtsZ complex. Although our SAR studies did not
shed much light on specific interactions between the analogues
and FtsZ, we discovered a derivative that could be pursued in
photo-cross-linking studies as a new avenue for probing this
small molecule−protein interaction. Azide 16 is under
investigation as a potential photo-cross-linker.
REFERENCES
■
(1) Alanis, A. J. Resistance to antibiotics: Are we in the post-
antibiotic era? Arch. Med. Res. 2005, 36, 697−705.
(2) Antibiotic resistance threats in the United States, 2013. http://
www.cdc.gov/drugresistance/threat-report-2013/index.html (accessed
November 18, 2014).
(3) Emmerson, A. M.; Jones, A. M. The quinolones: decades of
development and use. J. Antimicrob. Chemother. 2003, 51, 13−20.
(4) Appelbaum, P. C.; Hunter, P. A. The fluoroquinolone
antibacterials: past, present and future perspectives. Int. J. Antimicrob.
Agents 2000, 16, 5−15.
(5) Sass, P.; Brotz-Oesterhelt, H. Bacterial cell division as a target for
̈
new antibiotics. Curr. Opin. Microbiol. 2013, 16, 522−530.
(6) den Blaauwen, T.; Andreu, J. M.; Monasterio, O. Bacterial cell
division proteins as antibiotic targets. Bioorg. Chem. 2014, 55, 27−38.
(7) Lutkenhaus, J.; Pichoff, S.; Du, S. Bacterial cytokinesis: From Z
ring to divisome. Cytoskeleton 2012, 69, 778−790.
(8) Matesanz, R.; Trigili, C.; Rodríguez-Salarichs, J.; Zanardi, I.; Pera,
́
B.; Nogales, A.; Fang, W.-S.; Jímenez-Barbero, J.; Canales, A.;
Barasoain, I.; Ojima, I.; Díaz, J. F. Taxanes with high potency inducing
tubulin assembly overcome tumoural cell resistances. Bioorg. Med.
Chem. 2014, 22, 5078−5090.
(9) Kingston, D. G. I.; Snyder, J. P. The quest for a simple bioactive
analog of paclitaxel as a potential anticancer agent. Acc. Chem. Res.
2014, 47, 2682−2691.
ASSOCIATED CONTENT
* Supporting Information
■
́
(10) Pagano, A.; Honore, S.; Mohan, R.; Berges, R.; Akhmanova, A.;
S
Braguer, D. Epothilone B inhibits migration of glioblastoma cells by
inducing microtubule catastrophes and affecting EB1 accumulation at
microtubule plus ends. Biochem. Pharmacol. 2012, 84, 432−443.
(11) Yang, Z.; Wu, W.; Wang, J.; Liu, L.; Li, L.; Yang, J.; Wang, G.;
Cao, D.; Zhang, R.; Tang, M.; Wen, J.; Zhu, J.; Xiang, W.; Wang, F.;
Ma, L.; Xiang, M.; You, J.; Chen, L. Synthesis and biological evaluation
of novel millepachine derivatives as a new class of tubulin
polymerization inhibitors. J. Med. Chem. 2014, 57, 7977−7989.
(12) Ravelli, R. B. G.; Gigant, B.; Curmi, P. A.; Jourdain, I.; Lachkar,
S.; Sobel, A.; Knossow, M. Insight into tubulin regulation from a
complex with colchicine and a stathmin-like domain. Nature 2004,
428, 198−202.
Experimental details and characterization data for all synthetic
products and intermediates; FtsZ GTPase assay; GTP
competition experiment. This material is available free of
charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*E-mail: jtshaw@ucdavis.edu.
■
Funding
This work was supported by the National Institutes of Heath
(NIH/NIAID, R01AI08093, R01AI08093-04S1; NIH/NIGMS,
T32-GM008799). G.M.N. and T.E.O. acknowledge support in
the form of predoctoral fellowships from GAANN/DOEd and
the Alfred P. Sloan Foundation. L.A.E.P. thanks CNPq
(13) Gigant, B.; Wang, C.; Ravelli, R. B. G.; Roussi, F.; Steinmetz, M.
O.; Curmi, P. A.; Sobel, A.; Knossow, M. Structural basis for the
regulation of tubulin by vinblastine. Nature 2005, 435, 519−522.
(14) Ojima, I.; Kumar, K.; Awasthi, D.; Vineberg, J. G. Drug
discovery targeting cell division proteins, microtubules and FtsZ.
Bioorg. Med. Chem. 2014, 22, 5060−5077.
́
(Conselho Nacional de Desenvolvimento Cientıfico Tecnolo-
́
gico), Brazil. F.J.S. thanks LSAMP/CAMP. Z.Y. thanks the
D
DOI: 10.1021/ml500497s
ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX

ACS Medicinal Chemistry Letters
Letter
(15) Kelley, C.; Zhang, Y.; Parhi, A.; Kaul, M.; Pilch, D. S.; LaVoie, E.
J. 3-Phenyl substituted 6,7-dimethoxyisoquinoline derivatives as FtsZ-
targeting antibacterial agents. Bioorg. Med. Chem. 2012, 20, 7012−
7029.
(16) Ito, H.; Ura, A.; Oyamada, Y.; Tanitame, A.; Yoshida, H.;
Yamada, S.; Wachi, M.; Yamagishi, J.-i A 4-aminofurazan derivative
A189inhibits assembly of bacterial cell division protein FtsZ in vitro
and in vivo. Microbiol. Immunol. 2006, 50, 759−764.
(17) Wang, J.; Galgoci, A.; Kodali, S.; Herath, K. B.; Jayasuriya, H.;
Dorso, K.; Vicente, F.; Gonzalez, A.; Cully, D.; Bramhill, D.; Singh, S.
́
kinases (CDKs), Janus kinase 2 (JAK2), and fms-like tyrosine kinase-3
(FLT3) for the treatment of cancer. J. Med. Chem. 2012, 55, 169−196.
(30) Xu, H.; Tian, H.; Zheng, L.; Liu, Q.; Wang, L.; Zhang, S.
Synthesis of chiral benzimidazoles as acylating agents for kinetic
resolution of racemic α-amino esters. J. Heterocycl. Chem. 2012, 49,
1108−1113.
(31) Chalmers, K. H.; De Luca, E.; Hogg, N. H. M.; Kenwright, A.
M.; Kuprov, I.; Parker, D.; Botta, M.; Wilson, J. I.; Blamire, A. M.
Design principles and theory of paramagnetic fluorine-labelled
lanthanide complexes as probes for 19F magnetic resonance: a
proof-of-concept study. ChemEur. J. 2010, 16, 134−148.
(32) Gege, C.; Schneider, M.; Chevrier, C.; Deng, H.; Sucholeiki, I.;
Gallagher, B. M., Jr.; Bosies, M.; Steeneck, C.; Wu, X.; Hochguertel,
M.; Nolte, B.; Taveras, A. Preparation of Heterobicyclic Metalloprotease
Inhibitors. WO2008063668A1, 2008.
(33) Best, M. D.; Brik, A.; Chapman, E.; Lee, L. V.; Cheng, W.-C.;
Wong, C.-H. Rapid discovery of potent sulfotransferase inhibitors by
diversity-oriented reaction in microplates followed by in situ screening.
ChemBioChem 2004, 5, 811−819.
(34) Milkiewicz, K. L.; Aimone, L. D.; Albom, M. S.; Angeles, T. S.;
Chang, H.; Grobelny, J. V.; Husten, J.; LoSardo, C.; Miknyoczki, S.;
Murthy, S.; Rolon-Steele, D.; Underiner, T. L.; Weinberg, L. R.;
Worrell, C. S.; Zeigler, K. S.; Dorsey, B. D. Improvement in oral
bioavailability of 2,4-diaminopyrimidine c-Met inhibitors by incorpo-
ration of a 3-amidobenzazepin-2-one group. Bioorg. Med. Chem. 2011,
19, 6274−6284.
Discovery of a small molecule that inhibits cell division by blocking
FtsZ, a novel therapeutic target of antibiotics. J. Biol. Chem. 2003, 278,
44424−44428.
(18) Lappchen, T.; Hartog, A. F.; Pinas, V. A.; Koomen, G.-J.; den
̈
Blaauwen, T. GTP Analogue Inhibits Polymerization and GTPase
Activity of the Bacterial Protein FtsZ without Affecting Its Eukaryotic
Homologue Tubulin†. Biochemistry 2005, 44, 7879−7884.
(19) Anderson, D. E.; Kim, M. B.; Moore, J. T.; O’Brien, T. E.; Sorto,
N. A.; Grove, C. I.; Lackner, L. L.; Ames, J. B.; Shaw, J. T. Comparison
of small molecule inhibitors of the bacterial cell division protein FtsZ
and identification of a reliable cross-species inhibitor. ACS Chem. Biol.
2012, 7, 1918−1928.
(20) Foss, M. H.; Eun, Y.-J.; Grove, C. I.; Pauw, D. A.; Sorto, N. A.;
Rensvold, J. W.; Pagliarini, D. J.; Shaw, J. T.; Weibel, D. B. Inhibitors
of bacterial tubulin target bacterial membranes in vivo. MedChem-
Comm 2013, 4, 112−119.
(35) Jager, W. F.; Hammink, T. S.; van den Berg, O.; Grozema, F. C.
Highly sensitive water-soluble fluorescent pH sensors based on the 7-
amino-1-methylquinolinium chromophore. J. Org. Chem. 2010, 75,
2169−2178.
(21) Haydon, D. J.; Stokes, N. R.; Ure, R.; Galbraith, G.; Bennett, J.
M.; Brown, D. R.; Baker, P. J.; Barynin, V. V.; Rice, D. W.;
Sedelnikova, S. E.; Heal, J. R.; Sheridan, J. M.; Aiwale, S. T.; Chauhan,
P. K.; Srivastava, A.; Taneja, A.; Collins, I.; Errington, J.; Czaplewski, L.
G. An Inhibitor of FtsZ with Potent and Selective Anti-Staphylococcal
Activity. Science 2008, 321, 1673−1675.
(36) Andersen, J.; Madsen, U.; Bjorkling, F.; Liang, X. Rapid
̈
synthesis of aryl azides from aryl halides under mild conditions. Synlett
2005, 2005, 2209−2213.
(22) Andreu, J. M.; Schaffner-Barbero, C.; Huecas, S.; Alonso, D.;
Lopez-Rodriguez, M. L.; Ruiz-Avila, L. B.; Nunez-Ramírez, R.; Llorca,
́
̃
O.; Martín-Galiano, A. J. The antibacterial cell division inhibitor
PC190723 is an FtsZ polymer-stabilizing agent that induces filament
assembly and condensation. J. Biol. Chem. 2010, 285, 14239−14246.
(23) Elsen, N. L.; Lu, J.; Parthasarathy, G.; Reid, J. C.; Sharma, S.;
Soisson, S. M.; Lumb, K. J. Mechanism of action of the cell-division
inhibitor PC190723: modulation of FtsZ assembly cooperativity. J.
Am. Chem. Soc. 2012, 134, 12342−12345.
(24) Margalit, D. N.; Romberg, L.; Mets, R. B.; Hebert, A. M.;
Mitchison, T. J.; Kirschner, M. W.; RayChaudhuri, D. Targeting cell
division: Small-molecule inhibitors of FtsZ GTPase perturb cytokinetic
ring assembly and induce bacterial lethality. Proc. Natl. Acad. Sci. U.S.A.
2004, 101, 11821−11826.
(25) Hopkins, A. L.; Keseru, G. M.; Leeson, P. D.; Rees, D. C.;
Reynolds, C. H. The role of ligand efficiency metrics in drug discovery.
Nat. Rev. Drug Discovery 2014, 13, 105−121.
(26) Ingerman, E.; Nunnari, J. A Continuous, Regenerative Coupled
GTPase Assay for Dynamin-Related Proteins. In Methods in
Enzymology; William, E., Balch, C. J. D., Alan, H., Eds.; Academic
Press: New York, 2005; Vol. 404, pp 611−619.
(27) Moseley, J. D.; Murray, P. M.; Turp, E. R.; Tyler, S. N. G.; Burn,
R. T. A mild robust generic protocol for the Suzuki reaction using an
air stable catalyst. Tetrahedron 2012, 68, 6010−6017.
(28) Okano, M.; Mito, J.; Maruyama, Y.; Masuda, H.; Niwa, T.;
Nakagawa, S.-i.; Nakamura, Y.; Matsuura, A. Discovery and structure−
activity relationships of 4-aminoquinazoline derivatives, a novel class of
opioid receptor like-1 (ORL1) antagonists. Bioorg. Med. Chem. 2009,
17, 119−132.
(29) William, A. D.; Lee, A. C. H.; Goh, K. C.; Blanchard, S.;
Poulsen, A.; Teo, E. L.; Nagaraj, H.; Lee, C. P.; Wang, H.; Williams,
M.; Sun, E. T.; Hu, C.; Jayaraman, R.; Pasha, M. K.; Ethirajulu, K.;
Wood, J. M.; Dymock, B. W. Discovery of kinase spectrum selective
macrocycle (16E)-14-methyl-20-oxa-5,7,14,26-tetraazatetracyclo-
[19.3.1.1(2,6).1(8,12)]heptacosa-1(25),2(26),3,5,8(27),9,11,16,21,23-
decaene (SB1317/TG02), a potent inhibitor of cyclin dependent
E
DOI: 10.1021/ml500497s
ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX