Structural Studies on 4,5-Disubstituted 2-Aminoimidazole-Based Biofilm Modulators that Suppress Bacterial Resistance to β-Lactams

Article abstract of DOI:10.1002/cmdc.201200350

A library of 4,5-disubstituted 2-aminoimidazole triazole amide (2-AITA) conjugates has been successfully assembled. Upon biological screening, this class of small molecules was discovered as enhanced biofilm regulators through non-microbicidal mechanisms against methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Acinetobacter baumannii (MDRAB), with active concentrations in the low micromolar range. The library was also subjected to synergism and resensitization studies with β-lactam antibiotics against MRSA. Lead compounds were identified that suppress the antibiotic resistance of MRSA by working synergistically with oxacillin, a β-lactam antibiotic resistant to penicillinase. A further structure-activity relationship (SAR) study on the parent 2-AITA compound delivered a 2-aminoimidazole diamide (2-AIDA) conjugate with significantly increased synergistic activity with oxacillin against MRSA, decreasing the MIC value of the β-lactam antibiotic by 64-fold. Increased anti-biofilm activity did not necessarily lead to increased suppression of antibiotic resistance, which indicates that biofilm inhibition and resensitization are most likely occurring via distinct mechanisms.

Full text of DOI:10.1002/cmdc.201200350

MED
DOI: 10.1002/cmdc.201200350
Structural Studies on 4,5-Disubstituted 2-Aminoimidazole-
Based Biofilm Modulators that Suppress Bacterial
Resistance to b-Lactams
Zhaoming Su, Andrew A. Yeagley, Rui Su, Lingling Peng, and Christian Melander*[a]
A library of 4,5-disubstituted 2-aminoimidazole triazole amide
(2-AITA) conjugates has been successfully assembled. Upon
biological screening, this class of small molecules was discov-
ered as enhanced biofilm regulators through non-microbicidal
mechanisms against methicillin-resistant Staphylococcus aureus
(MRSA) and multidrug-resistant Acinetobacter baumannii
(MDRAB), with active concentrations in the low micromolar
range. The library was also subjected to synergism and resensi-
tization studies with b-lactam antibiotics against MRSA. Lead
compounds were identified that suppress the antibiotic resist-
ance of MRSA by working synergistically with oxacillin, a b-
lactam antibiotic resistant to penicillinase. A further structure–
activity relationship (SAR) study on the parent 2-AITA com-
pound delivered a 2-aminoimidazole diamide (2-AIDA) conju-
gate with significantly increased synergistic activity with oxacil-
lin against MRSA, decreasing the MIC value of the b-lactam an-
tibiotic by 64-fold. Increased anti-biofilm activity did not neces-
sarily lead to increased suppression of antibiotic resistance,
which indicates that biofilm inhibition and resensitization are
most likely occurring via distinct mechanisms.
Introduction
Infectious disease is the second leading cause of mortality
throughout the world, accounting for more than 25% of the
annual global deaths, and remains a serious threat to our soci-
ety.[1] This scenario has been exacerbated in the past decades
by the emergence of wide-spread, drug-resistant pathogens.[2]
Bacteria such as methicillin-resistant Staphylococcus aureus
(MRSA) and multidrug-resistant Acinetobacter baumannii
(MDRAB) are now common nosocomial pathogens and medi-
ate infections that are extremely difficult or even impossible to
treat.[3] MRSA accounts for 80% of the hospital-acquired
S. aureus infections and is now a greater cause of deaths annu-
ally in comparison with complications due to HIV,[4,5] while
MDRAB is related to many cases of serious infections among
wounded soldiers in the Middle East.[6]
films through non-microbicidal mechanisms across bacterial
order, class and phylum.[14] Further structure–activity relation-
ship (SAR) studies on these 2-AIT analogues have identified
molecules with improved anti-biofilm activity.[15]
Given the significant pressure that antibiotic-resistant bacte-
ria have posed on the medical community and contrasted with
Bacterial biofilms, defined as sessile communities of microor-
ganisms that coexist as highly differentiated associates in an
extracellular matrix of exo-polysaccharides,[7] play a significant
role in the development of antibiotic resistance by bacteria.[8]
Within a biofilm state, bacteria are up to 1000-fold more resist-
ant to conventional antibiotics in comparison with their plank-
tonic counterparts.[9] Biofilms have been recognized over the
past decade as a global threat.[10] Approximately 80% of the
microbial mass on earth is in a biofilm state, and the US Na-
tional Institutes of Health (NIH) estimates that over 80% of
bacterial infections in humans are related to biofilms.[11]
the scarce development of novel antibiotics,[16] methods to
deal with the threat of multidrug-resistant bacteria are sorely
needed. Recently, Klitgaard and co-workers reported that thio-
ridazine, an antipsychotic drug, was able to reverse oxacillin re-
sistance in MRSA without affecting bacteria growth.[17] In an-
A number of natural products, such as the marine alkaloid
oroidin (1), are known to possess moderate anti-biofilm activi-
ty.[12] Given the ubiquitous nature of biofilms in antimicrobial
therapy, efforts have been directed toward the development
[a] Z. Su, Dr. A. A. Yeagley, R. Su, Dr. L. Peng, Dr. C. Melander
Department of Chemistry, North Carolina State University
2620 Yarborough Drive, Raleigh, NC 27695-8204 (USA)
E-mail: christian_melander@ncsu.edu
of small molecules that modulate biofilm development.[13]
A
class of 2-aminoimidazole triazole conjugates, exemplified here
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/cmdc.201200350.
by 2-AIT (2), has been discovered to inhibit and disperse bio-
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other study, we found that 2-AI (3) was able to suppress carba-
penem resistance in New Delhi metallo-b-lactamase-1 (NDM-
1)-producing Klebsiella pneumoniae.[18]
vious findings on polysubstituted 2AIs.[19,21] Furthermore, these
compounds work synergistically with oxacillin against MRSA
(ATCC# BAA-44). Compounds with heterocyclic substitutions
were found to be less toxic to bacteria and continue to regu-
late biofilm formation through non-microbicidal mechanisms.
The necessity of the triazole was also investigated, and a 2-
aminoimidazole diamide conjugate (2-AIDA) was identified
with augmented resensitization activity against MRSA toward
oxacillin.
In an effort to combat antibiotic resistance and reveal a cor-
relation between antibiotic resistance and biofilm formation,
we screened our in-house 2-aminoimidazole (2-AI) library seek-
ing dual inhibitors of biofilm formation and b-lactam resistance
in MRSA. From these studies, the 2-aminoimidazole triazole
amide conjugate 4 (2-AITA) was identified as the most active
molecule to resensitize a representative MRSA strain (ATCC
BAA-44) toward oxacillin. In order to maximize the biological
activity, we were interested in studying the impact of installing
a 4,5-disubstitution pattern on 2-AITA (4). It has been previous-
ly demonstrated that a 4,5-disubstitution pattern enhances
biological activity, and 2-AI analogues with aromatic substitu-
tions were most active.[19,20] Herein, we report the assembly of
4,5-disubstituted 2-AITA derivatives with a variety of aromatic
substitutions, including heterocycles, based on the use of
Weinreb amide intermediates and organometallic additions.[20]
This class of 4,5-disubstituted 2-AITA analogues possess im-
proved antimicrobial activity, which is consistent with our pre-
Results and Discussion
Synthesis of the 4,5-disubstituted 2-AITA library is outlined in
Scheme 1. Protected a-amino-alkynyl ethylester 5 and azido
benzamide 6 were prepared as previously described.[20,22] The
copper-catalyzed [3+2] cycloaddition (click reaction) was per-
formed between 5 and 6 to deliver desired triazole 7 in 84%
yield. Triazole 7 was then treated with N,O-dimethylhydroxya-
mine hydrochloride and isopropylmagnesium chloride to gen-
erate target Weinreb amide 8 in 95% yield. With amide 8 in
hand, a variety of commercially available Grignard reagents
Scheme 1. Synthetic route to 4,5-disubstituted 2AITAs. Reagents and conditions: a) sodium ascorbate, CuSO4, tBuOH/H2O/CH2Cl2 (2:2:1), RT, 12 h (84%); b) O,N-
dimethylhydroxyamine·HCl, iPrMgCl, THF, ꢀ20!08C, 3 h (95%); c) RMgBr, THF, ꢀ20!08C, 4 h; d) 2n HCl, EtOH, RT, 12 h; e) NH2CN, EtOH/H2O (1:1), pH 4.3,
958C, 3 h. Yields given for compounds 10 are overall yields from 8 (three steps).
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were reacted with 8 to yield corresponding ketones 9. Magne-
sium/lithium reagents of heterocycles and some phenyl deriva-
tives were also generated in situ from the corresponding aro-
matics or aryl halides (Scheme 2). Deprotection of ketones 9
Table 1. Inhibition of MRSA and MDRAB biofilm formation by com-
pounds 4 and 10a–w.
Compd
IC50 [mm][a]
Compd
IC50 [mm][a]
Compd
IC50 [mm][a]
MRSA
10a
10b
10c
10d
10e
10 f
4.1ꢁ0.3
2.1ꢁ1.0
2.9ꢁ0.7
3.7ꢁ2.3
2.8ꢁ0.5
3.5ꢁ0.8
3.6ꢁ0.8
10i
10j
8.7ꢁ1.6
4.4ꢁ0.6
3.9ꢁ0.3
3.6ꢁ1.0
2.0ꢁ0.2
2.3ꢁ0.6
13.9ꢁ2.7
7.2ꢁ1.8[b]
10q
10r
10s
10t
10u
10v
10w
4
6.0ꢁ2.0
10.9ꢁ1.9
5.7ꢁ0.5
10k
10l
10m
10n
10o
4.8ꢁ0.7
2.6ꢁ0.9
19.2ꢁ1.8
4.2ꢁ1.0[b]
15.2ꢁ1.7[b]
10g
10h
3.7ꢁ0.8[b] 10p
MDRAB
10e
25.8ꢁ3.4[b] 10q
69.4ꢁ6.8[b] 10t
50.4ꢁ13.4[b]
[a] Values represent the mean ꢁSD of at least three independent experi-
ments. [b] Compound has no affect on bacteria growth.
parent compound 4 (IC50 =15.2 mm), compounds 10h, 10p
and 10w exhibited increased activity to modulate MRSA bio-
films through a non-microbicidal mechanism (IC50 values of 3.7,
7.2, and 4.2 mm, respectively).
Next, we assessed the ability of the pilot library to reverse
antibiotic resistance of MRSA toward b-lactams. In this assay,
the minimum inhibitory concentration (MIC) of each 4,5-disub-
stituted 2-AITA was first determined, and 25% of the MIC con-
centration of each compound was subsequently employed in
the resensitization activity. It is our experience from previous
studies that 2-AI derivatives typically exhibit weak microbicidal
activity when tested at 25% of their MIC values, thus allowing
us to attribute the suppression of antibiotic resistance mainly
to non-microbicidal effects of the compounds. MRSA was pre-
treated with each compound for 30 min, and the MIC values
for oxacillin and penicillin G were established (in the presence
of 25% MIC of each 2-AI compound; Table 2). We previously
established that parent compound 4 decreases the MIC value
of oxacillin against the BAA-44 strain of MRSA by fourfold.[19]
Compounds 10e, 10m and 10p showed comparative resensiti-
zation activity and lowered the MIC value of oxacillin against
MRSA by fourfold. The library was also screened for the ability
Scheme 2. Preparation of aryl Grignard/lithium reagents. Reagents and condi-
tions: Method A: 1) nBuLi, THF, ꢀ78–08C, 2 h; 2) MgBr2·Et2O, THF, 08C-RT,
1 h; Method B: Mg turnings, LiCl, DIBAL (I2), THF, RT, 4 h; Method C: iPrMgCl·-
LiCl, ꢀ158C-RT, 6 h; Method D: nBuLi, ꢀ788C, Et2O, 4 h.
with 2n hydrochloric acid in ethanol and cyclization with cyan-
amide was performed in tandem to deliver the final 4,5-disub-
stituted 2-AITA derivatives (10). We found that the aminoke-
tones resulting from addition of 2-allylphenyl, 2-pyridinyl, and
4-quinolinyl organometallic reagents were unstable to the de-
protection/cyclization sequence and so were not studied fur-
ther. After purification (CH2Cl2/MeOH/NH3), all 2-AITA deriva-
tives were converted to their hydrochloride salts for biological
screening.
The pilot library was first tested for its anti-biofilm activity at
100 mm against MRSA and MDRAB (ATCC BAA-1605) using
a crystal violet reporter assay.[23] Compounds that produced
>95% biofilm inhibition activity were then subjected to
a dose–response study, and the IC50 value for each compound
was determined. This data is summarized in Table 1. When the
library was screened for biofilm inhibition against MDRAB,
most compounds showed a precipitous drop over a narrow
concentration range in their dose–response curves that typical-
ly indicates that biofilm inhibition is acting through a strict mi-
crobicidal mechanism. However, compounds 10e, 10q and
10t were able to modulate biofilm development without ef-
fecting bacterial growth (Table 1), with IC50 values of 25.8 mm,
69.4 mm, and 50.4 mm, respectively. In comparison, parent 2-
AITA 4 inhibited MDRAB biofilm formation <5% at 100 mm. A
number of compounds were identified that inhibit the devel-
opment of MRSA biofilm development, yet a majority of these
compounds also affected bacterial growth. In comparison with
Table 2. Resensitization of MRSA to oxacillin and penicillin G.
MIC [mgmLꢀ1
]
MIC [mgmLꢀ1
]
Compd (MIC/
test concn)[a]
Compd (MIC/
oxacillin penicillin test concn)[a] oxacillin penicillin
10a (4/1)
10b (2/0.5)
10c (2/0.5)
10d (2/0.5)
10e (8/2)
10 f (4/1)
10g (4/1)
10h (8/2)
10i (16/4)
10j (4/1)
16
32
16
16
8
16
32
16
16
32
32
32
32
32
32
32
16
32
32
32
32
32
32
32
10m (4/1)
10n (4/1)
10o (16/4)
10p (16/4)
10q (8/2)
10r (16/4)
10s (8/2)
10t (16/4)
10u (8/2)
10v (32/8)
10w (8/2)
no compd
8
16
16
8
16
16
32
16
16
32
32
32
16
16
32
16
16
32
32
16
16
32
32
32
10k (4/1)
10l (2/0.5)
[a] MIC values and test concentrations are given in mgmLꢀ1
.
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to resensitize MDRAB to the effects of imipenem, a broad-spec-
trum b-lactam antibiotic. None of the compounds elicited any
appreciable resensitization activity against MDRAB, recording
less than a twofold decrease in the MIC value of imipenem.
As resensitization activity was not significantly improved by
imparting the 4,5-disubstitution pattern on 2-AITA (4), we
elected to pursue additional SAR studies to better understand
the structural requirements necessary to augment activity. The
parent compound 2-AITA (4) consists of three functional re-
gions: the 2-AI head, the triazole linker, and benzamide tail
(Figure 1). Since the tail region has been previously modi-
fied,[22] and modifications to the head region are described
benzylating 16 with hydrogen and palladium on carbon to
generate the corresponding carboxylic acids, which were then
coupled with either 4-pentylaniline or 17 followed by Boc de-
protection to give desired products 22 and 23 in 53% and
61% yield, respectively.
Compounds 20–23 were screened for anti-biofilm and resen-
sitization activity, and the results are summarized in Table 3.
Gratifyingly, this class of 2-AI derivatives was also able to inhib-
it MRSA and MDRAB biofilm formation via non-microbicidal
mechanisms. More importantly, derivative 23 was identified to
possess significantly enhanced resensitization activity and sup-
pressed b-lactam resistance of MRSA by lowering the MIC
value of oxacillin from 32 mgmLꢀ1 to 0.5 mgmLꢀ1 (64-fold) and
the MIC value of penicillin G from 32 mgmLꢀ1 to 2 mgmLꢀ1 (16-
fold) when the bacteria was grown in the presence of
16 mgmLꢀ1 (35.6 mm) of compound 23. Growth curve analysis
indicated that all four compounds altered early (0–8 h) MRSA
growth, with 20 having the weakest effect; however, bacterial
growth was equivalent for all treated and untreated samples
by 24 h. Parent compound 4 and the most active derivative
(23) have similar effects on bacteria growth inhibition (see
Supporting Information).
Figure 1. Overview of the structure–activity relationship (SAR) study of
parent compound 2-AITA (4).
Given the activities of the lead compounds, a checkerboard
assay was employed to determine the synergistic activity of all
2-AI derivatives in combination with oxacillin.[25] The SFIC value
is used to evaluate whether two combined agents are working
synergistically, and when the SFIC value is less than or equal
to 0.5, the combination is considered to be synergistic. As
shown in Table 4, most compounds work synergistically with
oxacillin, with derivative 23 determined to be the most promis-
ing compound with a SFIC value of 0.25.
above, the last region left for modification is the triazole. Our
initial thought was to replace the triazole with an amide
moiety based upon our earlier findings that the triazole and
amide functionalities are interchangeable in the context of 2-
AI biological activity and that replacement of one with the
other can result in augmentation of activity.[24]
The approach employed to access derivatives of 2-AITA (4)
with the triazole moiety either removed or replaced with an
amide is outlined in Scheme 3. Bromohexanoic acid 11 was
treated with sodium azide to give azidohexanoic acid 12 in
84% yield. Acid 12 was reacted with oxalyl chloride and diazo-
methane followed by quenching the resulting a-diazoketone
with hydrogen bromide to generate the a-bromoketone inter-
mediate in 90% yield. Cyclization with tert-butyloxycarbonyl
(Boc)-protected guanidine (51% yield) and subsequent exhaus-
tive Boc protection (83% yield) delivered desired precursor
azido tri-Boc-protected 2-AI 13. Another precursor, tri-Boc-pro-
tected 2-AI benzoate 16, was generated through the treatment
of dicarboxylic acid 14 with acetic anhydride and benzyl alco-
hol to give the target benzyl-protected dicarboxylic acid (15)
in 44% yield. Acid 15 was then converted to the correspond-
ing a-bromoketone followed by cyclization with Boc-guanidine
and exhaustive Boc protection to deliver 16. Amide 17 was ac-
cessed by reduction of 6 with hydrogen in the presence of pal-
ladium on carbon, while 19 was generated from coupling of
18 with b-alanine in 45% yield.
Conclusions
We have synthesized a number of 4,5-disubstituted 2-AITA de-
rivatives and evaluated their anti-biofilm and antibiotic resensi-
tization activity against MRSA and MDRAB. For most of these
compounds, this substitution pattern increased the microbici-
dal and anti-biofilm activities. Compounds 10h, 10p, and 10w
were identified as lead compounds against MRSA, while com-
pounds 10e, 10q, 10t were most active against MDRAB; all six
compounds acted via a non-microbicidal mechanism. Com-
pounds with heterocycles fused with phenyl substitutions gen-
erally displayed enhanced anti-biofilm activity and less toxicity.
Unfortunately, no significant improvement in suppressing anti-
biotic resistance of MRSA toward b-lactams was observed in
comparison with parent compound 2-AITA (4). A further SAR
study indicated that replacement of the triazole moiety in
compound 4 with an amide enhanced its ability to suppress
antibiotic resistance of MRSA toward b-lactams without com-
promising the anti-biofilm activity. Compound 23 was identi-
fied as the most potent molecule in this study and decreased
the MIC value of oxacillin against MRSA by 64-fold. The fact
that augmentation of the anti-biofilm activity does not neces-
sarily lead to increased suppression of antibiotic resistance in-
dicates that biofilm inhibition and resensitization are most
likely occurring via distinct mechanisms. Further mechanistic
With all intermediates in hand, azide 13 was reduced to the
primary amine by palladium-catalyzed hydrogenation and cou-
pled with 18 or 19 in the presence of N-ethyl-N’-(3-dimethyla-
minopropyl)carbodiimide
(EDC),
N-hydroxybenzotriazole
(HOBt) and N,N-diisopropylethylamine (DIEA). Finally, Boc de-
protection with 2n hydrochloric acid in ethanol delivered
target 2-AI derivatives 20 and 21 in 23% and 78% yield, re-
spectively. Compounds 22 and 23 were accessed by first de-
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Scheme 3. Synthesis of 2-AI amide/diamide derivatives. Reagents and conditions: a) NaN3, DMF, RT, 12 h (84%); b) 1. oxalyl chloride, CH2Cl2, DMF (cat), 08C!
RT, 1 h; 2. CH2N2, Et2O/CH2Cl2 (1:1), 08C, 1 h; 3. HBr, 08C, 30 min (99%); c) Boc-guanidine, DMF, RT, 3 d (51%); d) Boc2O, DMAP, THF, RT, 12 h (87%); e) 1. Ac2O,
xylenes, reflux, 2 h; 2. BnOH, 608C, 12 h (44%); f) H2, Pd/C, 1 atm, THF, RT, 12 h; g) b-analine, Et3N, CH2Cl2, 08C!RT, 12 h (45%); h) 18, Et3N, CH2Cl2, 08C!RT,
12 h (23%); i) TFA/CH2Cl2 (1:4), RT, 12 h; j) 19, EDC·HCl, HOBt, DIEA, DMF, RT, 12 h (82%); k) 4-pentylaniline, EDC·HCl, HOBt, DIEA, DMF, RT, 12 h (63%); l) 17,
EDC·HCl, HOBt, DIEA, DMF, RT, 12 h (74%).
studies and evaluation of these classes of compounds in
Table 3. Biological activity of 2-AI amide/diamides derivatives.
animal models of infections are currently underway and will be
MIC [mgmLꢀ1
]
IC50 [mm]
reported in due course.
Compd (MIC/
test concn)[a]
oxacillin
penicillin
MRSA
MDRAB
20 (16/4)
21 (32/8)
22 (8/2)
23 (64/16)
no compd
4
4
16
0.5
32
16
16
16
2
14.6ꢁ1.8[b]
35.0ꢁ3.8
6.4ꢁ2.8
6.5ꢁ3.1
–
136.6ꢁ2.2
150.1ꢁ2.5
127.9ꢁ15.2
N/A
Experimental Section
Chemistry
General: All reagents were purchased from commercially available
sources and used without further purification. Chromatography
was performed using 60 ꢁ mesh standard grade silica gel from
Sorbtech (Atlanta, GA, USA). Infrared (IR) spectra were obtained on
a FT/IR-4100 spectrophotometer; n˜ are reported in cmꢀ1. UV/Vis
32
–
[a] MIC values and test concentrations against MRSA BAA-44 are given in
mgmLꢀ1. [b] Values represent the mean ꢁSD of at least three independ-
ent experiments.
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Furan-3-ylmagnesium bromide: 3-Bromofuran (0.294 g, 2 mmol)
in dry THF (2 mL) was reacted with Mg turnings (0.054 g,
2.2 mmol), LiCl (0.085 g, 2 mmol) and DIBAL (1.0m, 0.02 mL,
0.02 mmol) in dry THF (4 mL) for 3 h according to method B to de-
liver the desired Grignard reagent.
Table 4. Synergistic activity of all compounds with oxacillin against
MRSA.
Compd
SFIC[a]
Compd
SFIC[a]
Compd
SFIC[a]
10a
10b
10c
10d
10e
10 f
10g
10h
10i
0.62
0.62
0.5
0.5
0.5
0.62
1
0.53
0.56
0.38
10k
10l
10m
10n
10o
10p
10q
10r
10s
–
1
10t
10u
10v
10w
20
21
22
23
4
0.38
0.5
0.75
0.5
0.5
0.5
0.56
0.25
0.5
0.62
0.38
0.38
0.56
0.38
0.31
0.75
0.53
–
Method C: (4-Cyanophenyl)magnesium bromide: A flame-dried
vial (23ꢂ85 mm) was charged with 4-bromobenzonitrile (0.724 g,
4 mmol), cooled to ꢀ158C, and iPrMgCl·LiCl (4.5 mL, 0.93m) was
added. The reaction was stirred at ꢀ158C!08C for 3 h, giving the
desired Grignard reagent in 97% yield (0.86m, 4.5 mL), as deter-
mined by titration with salicylaldehyde phenylhydrazone.[26]
Method D: The appropriate aryl bromide in a flame-dried 50 mL
round-bottomed flask was dissolved in anhydrous Et2O and cooled
to ꢀ788C. The reaction was treated dropwise with nBuLi (1.6m)
and then stirred at ꢀ788C!ꢀ608C for 3 h.
Quinolin-3-ylmagnesium bromide: 3-Bromoquinoline (0.813 g,
3.9 mmol) and nBuLi (1.6m, 2.9 mL, 4.6 mmol) were reacted in dry
Et2O (12 mL) according to method D to deliver the desired lithium
reagent.
10j
–
–
[a] SFIC=FICCompd +FICAntibiotic
;
FICCompd =[MICCompd in combination]/
[MICCompd alone]; FICAntibiotic =[MICAntibiotic in combination]/[MICAntibiotic
alone]. The combination is considered synergistic if SFICꢂ0.5, indifferent
if 0.5<SFIC<2, and antagonistic if SFICꢃ2.
absorbance was recorded on a Genesys 10 scanning UV/Vis spec-
trophotometer; lmax are reported in nm. 1H NMR (400 MHz) and
13C NMR (100 MHz) spectra were recorded at 258C on Varian Mer-
cury spectrometers. Deuterated solvents were obtained from Cam-
bridge Isotope Labs and used as received. Chemical shifts (d) are
given in ppm relative to tetramethylsilane (TMS) or the respective
residual solvent peak. Coupling constants (J) are in given in Hertz
(Hz). Abbreviations used are s=singlet, bs=broad singlet, d=dou-
blet, dd=doublet of doublets, t=triplet, dt=doublet of triplets,
td=triplet of doublets, tt=triplet of triplets, bt=broad triplet, q=
quartet, m=multiplet, bm=broad multiplet. Mass spectrometry
(MS) was performed by the North Carolina State University Depart-
ment of Chemistry Mass Spectrometry Facility.
Synthesis of 4,5-disubstituted 2-AITA derivatives 10a–w
Ethyl
2-(diphenylmethyleneamino)-7-(1-(2-(4-pentylbenzami-
do)ethyl)-1H-1,2,3-triazol-4-yl)heptanoate (7): Compound
5
(2.167 g, 6 mmol) was dissolved in CH2Cl2/tBuOH/H2O (1:2:2,
50 mL) in a 150 mL round-bottomed flask. Compound 6 (1.874 g,
7.2 mmol) was added to the solution at RT. With vigorous stirring,
CuSO4 (0.144 g, 0.9 mmol) and sodium ascorbate (0.475 g,
2.4 mmol) were added, and the resulting solution was stirred at RT
for 12 h. The mixture was extracted with CH2Cl2 (3ꢂ15 mL). The
combined organic extracts were washed with brine (20 mL), dried
over Na2SO4, filtered and concentrated in vacuo. The resulting resi-
due was purified by column chromatography (hexane/EtOAc,
9:1!1:4) to afford target compound 7 as a yellow oil (3.135 g,
Full synthetic protocols for the preparation of Grignard/lithium re-
agents (S2) and the synthesis of 4,5-disubstituted-2-AITA deriva-
tives (S3), along with NMR data for compounds 7, 8, 10a–w (S20)
and conjugates 12–23 (S45) are available in the Supporting Infor-
mation.
1
84%): H NMR (400 MHz, CDCl3): d=8.03 (s, 1H), 7.76 (d, J=8.4 Hz,
2H), 7.62 (d, J=7.2 Hz, 2H), 7.41 (m, 3H), 7.35 (m, 2H), 7.28 (m,
2H), 7.15 (m, 4H), 4.52 (m, 2H), 4.14 (m, 2H), 4.04 (t, J=6.8 Hz,
1H), 3.88 (m, 2H), 2.58 (t, J=7.6 Hz, 4H), 1.90 (m, 2H), 1.57 (m,
4H), 1.29 (m, 6H), 1.23 (t, J=7.6 Hz, 3H), 1.22 (m, 2H), 0.87 ppm (t,
J=7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3): d=172.2, 170.1, 167.8,
147.8, 146.7, 139.2, 136.2, 131.1, 130.1, 128.5, 128.4, 128.3, 128.2,
127.8, 127.5, 127.1, 121.7, 65.1, 60.6, 49.0, 39.8, 35.5, 33.3, 31.1,
30.6, 29.0, 28.7, 25.5, 25.2, 22.2, 14.0, 13.8 ppm; HRMS (FAB) m/z
[M+H]+ calcd for C38H47N5O3: 622.3751, found 622.3759.
Preparation of Grignard/lithium reagents
Method A: The appropriate heterocycle was dissolved in anhy-
drous THF in a flame-dried 50 mL round-bottomed flask, and the
solution was cooled to ꢀ788C. nBuLi (1.6m) was added, and the
mixture was stirred for 2 h while warming to 08C. The resulting so-
lution was mixed with a slurry of MgBr2·Et2O in anhydrous THF at
08C and stirred at RT for 1 h until all solids were dissolved.
N-(2-(4-(6-(Diphenylmethyleneamino)-7-(methoxy-
(methyl)amino)-7-oxoheptyl)-1H-1,2,3-triazol-1-yl)ethyl)-4-pen-
tylbenzamide (8): A flame-dried 50 mL round-bottomed flask was
charged with 7 (1.819 g, 2.9 mmol) and anhydrous THF (10 mL).
The solution was stirred under nitrogen at ꢀ208C until 7 was fully
dissolved. The solution was then treated with N,O-dimethylhydrox-
ylamine hydrochloride (1.141 g, 11.7 mmol), and iPrMgCl (14.8 mL,
23.4 mmol, 1.58m) was then added dropwise, while the reaction
temperature was maintained below ꢀ58C. The resulting solution
was stirred at 08C for 3 h. The reaction was quenched with saturat-
ed aq NH4Cl (10 mL) and then extracted with EtOAc (3ꢂ10 mL).
The combined organic extracts were washed with brine (30 mL),
dried over Na2SO4, filtered and concentrated in vacuo. The result-
ing residue was purified by column chromatography (100% EtOAc)
Benzo[b]thiophen-2-ylmagnesium bromide: Benzo[b]thiophene
(0.805 g, 6 mmol) and nBuLi (1.6m, 3.75 mL, 6 mmol) in dry THF
(10 mL) was reacted with MgBr2·Et2O (1.549 g, 6 mmol) in dry THF
(10 mL) according to method A to deliver the desired Grignard re-
agent.
Benzofuran-2-ylmagnesium bromide: Benzofuran (0.236 g,
2 mmol) and nBuLi (1.6m, 1.25 mL, 6 mmol) in dry THF (3 mL) was
reacted with MgBr2·Et2O (0.516 g, 2 mmol) in dry THF (2 mL) ac-
cording to method A to deliver the desired Grignard reagent.
Method B: A flame-dried vial (23ꢂ85 mm) was charged with Mg
turnings and LiCl followed by diisobutylaluminum hydride (DIBAL)
in anhydrous THF. The resulting suspension was stirred at RT for
5 min. The resulting mixture was reacted with the appropriate aryl
bromide in dry THF and stirred at RT until all Mg had disappeared.
1
to give desired product 8 as a colorless oil (1.779 g, 95%): H NMR
(400 MHz, CDCl3): d=7.76 (m, 3H), 7.61 (d, J=7.6 Hz, 2H), 7.43 (m,
3H), 7.32 (m, 2H), 7.27 (m, 2H), 7.16 (m, 4H), 4.53 (t, J=6.0 Hz,
2H), 4.31 (t, J=6.4 Hz, 1H), 3.88 (m, 2H), 3.22 (s, 3H), 3.12 (s, 3H),
&6
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Resistance-Suppressing Biofilm Modulators
MED
2.59 (t, J=7.6 Hz, 4H), 1.58 (m, 4H), 1.30 (m, 10H), 0.87 ppm (t, J=
7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3): d=169.8, 168.2, 148.2,
147.2, 139.6, 137.1, 131.5, 130.4, 128.9, 128.8, 128.7, 128.7, 128.2,
128.0, 127.8, 127.5, 122.0, 62.9, 61.1, 49.4, 40.2, 36.0, 33.8, 31.6,
31.1, 29.4, 29.2, 29.1, 26.1, 25.7, 22.7, 14.3 ppm; IR (neat): n˜ =3324,
3135, 3059, 3027, 2930, 2856, 2360, 2340, 1957, 1817, 1771, 1652,
1615, 1571, 1541, 1503, 1444, 1383, 1291, 1181, 1143, 1050, 990,
855, 781, 734, 700 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=205, 238 nm;
HRMS (FAB) m/z [M+H]+ calcd for C38H48N6O3: 637.3861, found
637.3845.
7.23 (m, 2H), 7.18 (d, J=8.0 Hz, 2H), 6.98 (s, 1H), 4.60 (t, J=6.0 Hz,
2H), 3.82 (t, J=5.6 Hz, 2H), 2.75 (t, J=7.6 Hz, 2H), 2.65 (t, J=
7.6 Hz, 2H), 2.53 (t, J=8.0 Hz, 2H), 1.64 (m, 4H), 1.51 (m, 2H), 1.36
(m, 2H), 1.24 (m, 4H), 0.83 ppm (t, J=7.2 Hz, 3H); 13C NMR
(100 MHz, CD3OD): d=170.4, 155.8, 148.9, 148.6, 148.5, 146.7,
132.6, 129.7, 128.7, 128.5, 127.1, 126.2, 124.8, 124.0, 122.3, 115.3,
112.0, 104.0, 50.5, 41.1, 36.7, 32.6, 32.2, 30.0, 29.6, 29.3, 26.0, 25.3,
23.6, 14.5 ppm; IR (neat): n˜ =3396, 2933, 2856, 1685, 1653, 1542,
1124, 1092, 618 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=205, 229, 301 nm;
HRMS (FAB) m/z [M+H]+ calcd for C32H39N7O2: 554.3238, found
554.3220.
General procedure for tandem synthesis of 10: A flame-dried vial
(23ꢂ85 mm) was charged with compound 8 and anhydrous THF
(1 mL). The solution was stirred under nitrogen at ꢀ208C, and the
appropriate Grignard/lithium reagent was added dropwise. The re-
sulting mixture was allowed to warm to 08C and stirred for 4 h.
The reaction was quenched with saturated aq NH4Cl (2 mL), and
then extracted with EtOAc (3ꢂ2 mL). The combined organic ex-
tracts were washed with brine, dried over Na2SO4, filtered and con-
centrated in vacuo. The residue was dissolved in a minimum
amount of CH2Cl2 and purified by column chromatography
(hexane/EtOAc, 1:1). The desired a-diphenylmethyleneamino
ketone still contained a minor impurity that could only be ob-
served in 13C NMR; the crude material was carried forward. Ketone
9 was redissolved in EtOH, and the solution was treated with 2n
HCl and stirred at RT for 12 h. The pH of the resulting solution was
then adjusted to 4.3 with 0.1m aq NaOH. Cyanamide was added,
and the resulting mixture was heated at 958C for 3 h. The EtOH
was removed in vacuo, and the residue was purified by column
chromatography (CH2Cl2/MeOH (sat. NH3), 4:1) to afford target 4,5-
disubstituted 2-AITA 10 in its free base form. To form the HCl salt,
a solution of free base in MeOH (1 mL) was treated with concd
HCl. Removal of the solvent in vacuo delivered corresponding
10·HCl.
Synthesis of 2-AI amide/diamide conjugates 20–23
6-Azidohexanoic acid (12): A flame-dried 50 mL round-bottomed
flask was charged with 6-bromohexanoic acid 11 (3.901 g,
20 mmol) and anhydrous DMF (10 mL). NaN3 (5.201 g, 80 mmol)
was then added, and the reaction was stirred at RT for 12 h. The re-
sulting solution was diluted with CH2Cl2/H2O (1:1, 30 mL), and the
organic layer was separated and extracted with H2O (2ꢂ15 mL).
The combined aqueous portions was then back extracted with
CH2Cl2 (3ꢂ15 mL). The combined organic extracts were washed
with brine (20 mL), dried over Na2SO4, filtered and concentrated in
vacuo. Resulting product 12 was carried forward without further
purification (2.652 g, 84%): 1H NMR (400 MHz, CDCl3): d=3.28 (t,
J=7.2 Hz, 2H), 2.38 (t, J=7.6 Hz, 2H), 1.67 (m, 4H), 1.43 ppm (m,
2H).
7-Azido-1-bromoheptan-2-one:
Compound
12
(2.652 g,
16.9 mmol) was dissolved in dry CH2Cl2 (10 mL) in a flame-dried
100 mL round-bottomed flask. A catalytic amount of DMF (5 drops)
was added, and the solution was cooled to 08C. Oxalyl chloride
was added dropwise [note: vigorous effervescence occurs], and the
resulting solution was stirred for 15 min at 08C and then 1 h at RT.
The solvent was removed in vacuo, and the crude acyl chloride
was redissolved in anhydrous CH2Cl2 (20 mL) and added dropwise
at 08C to a solution of CH2N2 in Et2O (0.451 m, 150 mL), prepared
N-(2-(4-(5-(2-Amino-4-(4-hexylphenyl)-1H-imidazol-5-yl)pentyl)-
1H-1,2,3-triazol-1-yl)ethyl)-4-pentylbenzamide (10e): Compound
8 (0.098 g, 0.15 mmol) was treated with (4-hexylphenyl) magnesi-
um bromide (2.2 mL, 1.1 mmol, 0.5m), and the resulting crude
ketone 9e was reacted with 2n aq HCl (1.2 mL) in EtOH (1 mL) fol-
lowed by cyclization with cyanamide (0.157 g, 3.7 mmol) according
to the general procedure. Purification by column chromatography
afforded target compound 10e as a pale yellow solid (0.038 g,
from
N-methyl-N-nitroso-p-toluenesulfonamide
(diazald;
67.6 mmol) and KOH (15 g, 0.267 mol) in H2O (25 mL), EtOH
(35 mL) and Et2O (150 mL). The reaction was stirred at 08C for 1 h,
treated with concd HBr (48%; 7 mL) at 08C, and then stirred for an-
other 30 min at 08C. Saturated aq NaHCO3 (70 mL) was added to
the reaction at 08C, and the mixture was extracted with Et2O (3ꢂ
30 mL). The combined organic extracts were washed with saturat-
ed aq NaHCO3 (20 mL) and brine (20 mL), dried over Na2SO4, fil-
tered and concentrated in vacuo. Purification by column chroma-
tography (hexane/EtOAc, 9:1!1:1) gave the desired a-bromoke-
1
42% over three steps): H NMR (400 MHz, CD3OD): d=8.51 (s, 1H),
7.68 (d, J=8.0 Hz, 2H), 7.34 (d, J=8.4 Hz, 2H), 7.29 (d, J=8.0 Hz,
2H), 7.21 (d, J=8.0 Hz, 2H), 4.83 (t, J=5.6 Hz, 2H), 3.94 (t, J=
5.2 Hz, 2H), 2.84 (t, J=7.6 Hz, 2H), 2.61 (m, 6H), 1.59 (m, 8H), 1.31
(m, 12H), 0.87 ppm (m, 6H); 13C NMR (100 MHz, CD3OD): d=170.4,
148.7, 148.1, 145.9, 144.8, 132.3, 130.3, 129.7, 128.6, 128.2, 127.0,
123.9, 123.6, 54.0, 40.6, 36.8, 36.7, 33.0, 32.6, 32.2, 30.1, 29.7, 29.3,
29.0, 25.0, 24.2, 23.8, 23.6, 14.6, 14.5 ppm; IR (neat): n˜ =3319, 2929,
2851, 1683, 1653, 1541, 1507, 1457, 1397, 1138, 1124, 1099,
596 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=202, 220 nm; HRMS (FAB) m/z
[M+H]+ calcd for C36H51N7O: 598.4228, found 598.4212.
1
tone as a yellow oil (3.535 g, 90%): H NMR (400 MHz, CDCl3): d=
3.87 (s, 2H), 3.27 (t, J=6.8 Hz, 2H), 2.67 (t, J=7.2 Hz, 2H), 1.62 (m,
4H), 1.38 ppm (m, 2H); 13C NMR (100 MHz, CDCl3): d=202.0, 51.3,
39.7, 34.4, 28.8, 26.3, 23.4 ppm; HRMS (FAB) m/z [M+H]+ calcd for
C7H12BrN3O: 234.0236, found 234.0223.
tert-Butyl 2-amino-5-(5-azidopentyl)-1H-imidazole-1-carboxylate:
A 100 mL round-bottomed flask was charged with a-bromoketone
(3.535 g, 15.2 mmol) and DMF (20 mL). Boc-guanidine (5.714 g,
35.9 mmol) was then added, and the reaction was stirred at RT for
3 d. The resulting solution was mixed with H2O (20 mL) and EtOAc
(40 mL), and the mixture was extracted with H2O (3ꢂ20 mL). The
combined aqueous portions were extracted with EtOAc (1ꢂ20 mL),
and the combined organic extracts were washed with brine
(20 mL), dried over Na2SO4, filtered and concentrated in vacuo. The
resulting residue was purified by column chromatography
(hexane/EtOAc, 4:1!1:1) to afford the target Boc-2-AI as a pale
yellow solid (2.282 g, 51%): 1H NMR (400 MHz, CDCl3): d=6.44 (s,
N-(2-(4-(5-(2-Amino-4-(benzofuran-2-yl)-1H-imidazol-5-yl)pentyl)-
1H-1,2,3-triazol-1-yl)ethyl)-4-pentylbenzamide (10q): Compound
8 (0.078 g, 0.12 mmol) was treated with prepared benzofuran-2-yl-
MgBr (0.442 g, 2 mmol), and the resulting crude ketone 9q was re-
acted with 2n aq HCl (1.6 mL) in EtOH (1 mL) followed by cycliza-
tion with cyanamide (0.085 g, 2 mmol) according to the general
procedure. Purification by column chromatography afforded target
compound 10q as a pale yellow solid (0.036 g, 54% over three
steps): 1H NMR (400 MHz, CD3OD): d=7.73 (s, 1H), 7.66 (d, J=
8.4 Hz, 2H), 7.57 (dd, J=0.8, 7.6 Hz, 1H), 7.46 (d, J=8.4 Hz, 1H),
ChemMedChem 0000, 00, 1 – 11
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C. Melander et al.
MED
2H), 6.40 (s, 1H), 3.16 (t, J=7.2 Hz, 2H), 2.26 (t, J=7.6 Hz, 2H), 1.48
(m, 13H), 1.31 ppm (m, 2H); 13C NMR (100 MHz, CDCl3): d=150.7,
149.4, 138.5, 106.0, 84.2, 51.2, 28.5, 27.8, 27.7, 26.3, 26.2 ppm; IR
(neat): n˜ =3427, 3402, 3121, 2981, 2934, 2089, 1734, 1642, 1369,
1268, 1253, 1201, 1157, 1121, 884, 772 cmꢀ1; UV/Vis (CH2Cl2): lmax
(e)=259 nm; HRMS (FAB) m/z [M+H]+ calcd for C13H22N6O2:
295.1876, found 295.1885.
(100 MHz, CDCl3): d=173.8, 150.0, 149.7, 139.3, 136.3, 128.7, 128.4,
106.7, 84.8, 66.3, 34.5, 29.0, 28.2, 28.2, 25.0 ppm; IR (neat): n˜ =3454,
2935, 2860, 1734, 1643, 1456, 1370, 1253, 1160, 1123, 847, 773,
698 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=259 nm; HRMS (FAB) m/z [M+
H]+ calcd for C21H29N3O4: 388.2231, found 388.2218.
tert-Butyl 5-(6-(benzyloxy)-6-oxohexyl)-2-(bis(tert-butoxycarbo-
nyl)amino)-1H-imidazole-1-carboxylate (16): tert-Butyl 2-amino-5-
tert-Butyl
5-(5-azidopentyl)-2-(bis(tert-butoxycarbonyl)amino)-
(6-(benzyloxy)-6-oxohexyl)-1H-imida-zole-1-carboxylate
(2.214 g,
1H-imidazole-1-carboxylate (13): Boc-2-AI (1.751 g, 6 mmol) was
dissolved in dry THF (20 mL) in a 100 mL round-bottomed flask,
and the solution was treated with DMAP (0.073 g, 0.6 mmol) and
Boc2O (3.893 g, 17.9 mmol) and then stirred at RT for 12 h. The sol-
vent was removed in vacuo. Purification by column chromatogra-
phy (hexane/EtOAc, 9:1!1:1) gave desired product 13 as a pale
yellow oil (2.446 g, 83%): 1H NMR (400 MHz, CDCl3): d=6.94 (s,
1H), 3.09 (t, J=6.8 Hz, 2H), 2.37 (t, J=7.6 Hz, 2H), 1.41 (m, 13H),
1.25 ppm (m, 20H); 13C NMR (100 MHz, CDCl3): d=149.2, 146.2,
139.7, 137.4, 113.8, 85.3, 83.0, 51.1, 28.4, 28.0, 27.8, 27.6, 27.6,
25.8 ppm; IR (neat): n˜ =2979, 2936, 2863, 2096, 1807, 1752, 1585,
1537, 1458, 1395, 1370, 1276, 1254, 1150, 1119, 1100, 1019, 850,
772 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=244 nm; HRMS (FAB) m/z [M+
H]+ calcd for C23H38N6O6: 495.2926, found 495.2905.
5.7 mmol) was treated with DMAP (0.07 g, 0.6 mmol) and Boc2O
(3.739 g, 17.2 mmol) according to the same procedure described
for the synthesis of 13. Purification by column chromatography
(hexane/EtOAc, 4:1!1:1) afforded target product 16 as a pale
yellow oil (2.918 g, 87%): 1H NMR (400 MHz, CDCl3): d=7.30 (m,
5H), 7.04 (s, 1H), 5.06 (s, 2H), 2.46 (t, J=7.2 Hz, 2H), 2.30 (t, J=
7.6 Hz, 2H), 1.63 (m, 4H), 1.53 (s, 9H), 1.37 (s, 18H), 1.32 ppm (m,
2H); 13C NMR (100 MHz, CDCl3): d=173.5, 149.5, 146.6, 140.2,
137.6, 136.2, 128.6, 128.2, 114.0, 85.6, 83.3, 66.1, 34.3, 28.5, 28.4,
27.9, 27.7, 24.8 ppm; IR (neat): n˜ =2979, 2936, 2863, 1807, 1749,
1586, 1537, 1457, 1394, 1370, 1276, 1254, 1151, 1119, 1100, 1019,
850, 751, 69 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=244 nm; HRMS (FAB)
m/z [M+H]+ calcd for C31H45N3O8: 588.3279, found 588.3265.
N-(2-Aminoethyl)-4-pentylbenzamide (17): A vial (23ꢂ85 mm)
was charged with N-(2-azidoethyl)-4-pentylbenzamide 6 (0.2 g,
0.77 mmol) and anhydrous THF (6 mL), and the solution was treat-
ed with Pd/C (0.081 g, 0.08 mmol). The resulting solution was first
flushed with H2 for 5 min, and then stirred under 1 atm H2 for
12 h. The mixture was filtered through Celite, and the solvent was
evaporated in vacuo to deliver the desired crude primary amine,
which was used without further purification.
7-(Benzyloxy)-7-oxoheptanoic acid (15): A 1 L round-bottomed
flask was charged with heptanedioic acid 14 (6.403 g, 40 mmol)
and Ac2O (16.334 g, 160 mmol) in xylenes (500 mL). The reaction
was stirred at 1408C for 2 h. The solvent was then evaporated in
vacuo, and the resulting crude cyclic anhydride was redissolved in
BnOH (5 mL, 5.191 g, 48 mmol) and stirred at 608C for 12 h. Et2O
(30 mL) was added, and the reaction was extracted with saturated
aq NaHCO3 (3ꢂ20 mL). The combined aqueous extracts were acidi-
fied to pH 2 with 2n aq HCl. The acidic solution was then extract-
ed with Et2O (3ꢂ20 mL), and the combined organic extracts were
washed with brine (60 mL), dried over Na2SO4, filtered and concen-
trated in vacuo. The resulting residue was purified by column chro-
matography (hexane/EtOAc, 4:1!1:1) to afford target compound
3-(4-Pentylbenzamido)propanoic acid (19): A 50 mL round-bot-
tomed flask was charged with 4-pentylbenzoyl chloride 6 (1.054 g,
5 mmol) and anhydrous CH2Cl2 (6 mL). The mixture was cooled to
08C and treated with Et3N (1.012 g, 10 mmol) and b-analine
(0.534 g, 6 mmol) sequentially. The reaction was stirred for 12 h
while warming from 08C to RT. The resulting solution was treated
with 1n aq HCl (3 mL) and then extracted with CH2Cl2 (3ꢂ4 mL).
The combined organic extracts were washed with brine (12 mL),
dried over Na2SO4, filtered and concentrated in vacuo. The result-
ing residue was purified by column chromatography (hexane/
EtOAc, 2:1!1:2) to afford target compound 19 as a white solid
1
15 as a colorless oil (4.438 g, 44%): H NMR (400 MHz, CDCl3): d=
7.36 (m, 5H), 5.12 (s, 2H), 2.37 (t, J=8.0 Hz, 2H), 2.34 (t, J=7.6 Hz,
2H), 1.67 (m, 4H), 1.37 ppm (m, 2H); 13C NMR (100 MHz, CDCl3):
d=179.9, 173.6, 136.2, 128.8, 128.4, 66.4, 34.2, 34.0, 28.6, 24.7,
24.4 ppm; HRMS (FAB) m/z [M+H]+ calcd for C14H18O4: 251.1277,
found 251.1283.
1
(0.64 g, 45%): H NMR (400 MHz, CDCl3): d=10.32 (bs, 1H), 7.65 (d,
Benzyl 8-bromo-7-oxooctanoate: Compound 15 (4.438 g,
17.7 mmol) was reacted with oxalyl chloride (6.757 g, 53.2 mmol)
and diazald (15.205 g, 71 mmol) according to the same procedure
described for the synthesis of 7-azido-1-bromoheptan-2-one. Purifi-
cation by column chromatography (hexane/EtOAc, 9:1!1:1) af-
forded the target a-bromoketone (5.749 g, 99%): 1H NMR
(400 MHz, CDCl3): d=7.36 (m, 5H), 5.11 (s, 2H), 3.87 (s, 2H), 2.64 (t,
J=7.6 Hz, 2H), 2.36 (t, J=7.6 Hz, 2H), 1.61 (m, 4H), 1.33 ppm (m,
2H); 13C NMR (100 MHz, CDCl3): d=202.2, 173.6, 136.2, 128.8,
128.4, 66.4, 39.7, 34.5, 34.2, 28.6, 24.8, 23.6 ppm; HRMS (FAB) m/z
[M+H]+ calcd for C15H19BrO3: 327.0590, found 327.0579.
J=8.0 Hz, 2H), 7.20 (d, J=8.4 Hz, 2H), 7.13 (t, J=6.0 Hz, 1H), 3.70
(m, 2H), 2.67 (t, J=6.0 Hz, 2H), 2.60 (t, J=8.0 Hz, 2H), 1.58 (m, 2H),
1.30 (m, 4H), 0.87 ppm (t, J=6.8 Hz, 3H); 13C NMR (100 MHz,
CDCl3): d=177.0, 168.4, 147.4, 131.3, 128.8, 127.2, 35.9, 35.5, 34.0,
31.6, 31.0, 22.6, 14.2 ppm; IR (neat): n˜ =3342, 2952, 2925, 2852,
1698, 1636, 1539, 1509, 1454, 1431, 1294, 1225, 1076, 925, 853,
648, 626 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=235 nm; HRMS (FAB) m/z
[M+H]+ calcd for C15H21NO3: 264.1594, found 264.1586.
N-(5-(2-Amino-1H-imidazol-5-yl)pentyl)-4-pentylbenzamide (20):
A vial (23ꢂ85 mm) was charged with 13 (0.2 g, 0.4 mmol) and an-
hydrous THF (4 mL), and the solution was treated with Pd/C
(0.043 g, 0.04 mmol). The resulting solution was first flushed with
H2 for 5 min, and then stirred under 1 atm H2 for 12 h. The mixture
was filtered through Celite, and the solvent was evaporated in va-
cuo. The crude primary amine was redissolved in anhydrous CH2Cl2
(2 mL) and cooled to 08C. Et3N (0.047 g, 0.46 mmol) and 4-pentyl-
benzoyl chloride 18 (0.054 g, 0.25 mmol) were added, and the so-
lution was stirred for 12 h while warming from 08C to RT. Then,
the reaction was treated with trifluoroacetic acid (TFA; 0.5 mL,
6.53 mmol) and stirred at RT for 12 h. The solvent was removed in
tert-Butyl 2-amino-5-(6-(benzyloxy)-6-oxohexyl)-1H-imidazole-1-
carboxylate: Benzyl 8-bromo-7-oxooctanoate (5.749 g, 17.6 mmol)
was reacted with Boc-guanidine (8.416 g, 52.9 mmol) according to
the same procedure described for the synthesis of tert-butyl 2-
amino-5-(5-azidopentyl)-1H-imidazole-1-carboxylate. Purification by
column chromatography (hexane/EtOAc, 4:1!1:1) afforded the
target Boc-2-AI as a yellow oil (2.459 g, 36%): 1H NMR (400 MHz,
CDCl3): d=7.35 (m, 5H), 6.49 (s, 1H), 5.57 (s, 2H), 5.11 (s, 2H), 2.36
(m, 4H), 1.67 (m, 2H), 1.58 (m, 11H), 1.37 ppm (m, 2H); 13C NMR
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Resistance-Suppressing Biofilm Modulators
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vacuo, and the resulting residue was purified by column chroma-
tography (CH2Cl2/MeOH (sat. NH3), 20:1!4:1) to afford desired
product 20 as a pale yellow solid (0.018 g, 23% over three steps):
1H NMR (400 MHz, CD3OD): d=7.72 (d, J=8.0 Hz, 2H), 7.25 (d, J=
8.0 Hz, 2H), 6.48 (s, 1H), 3.37 (t, J=7.2 Hz, 2H), 2.64 (t, J=8.0 Hz,
2H), 2.50 (t, J=8.0 Hz, 2H), 1.63 (m, 6H), 1.42 (m, 2H), 1.32 (m,
4H), 0.89 ppm (t, J=6.8 Hz, 3H); 13C NMR (100 MHz, CD3OD): d=
170.4, 148.3, 133.2, 129.7, 129.1, 128.4, 109.8, 40.8, 36.8, 32.7, 32.3,
30.3, 29.0, 27.4, 25.5, 23.7, 14.5 ppm; IR (neat): n˜ =3382, 2923,
2850, 1632, 1403, 1070, 1019 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=205,
229 nm; HRMS (FAB) m/z [M+H]+ calcd for C20H30N4O: 343.2492,
found 343.2483.
692 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=205, 241 nm; HRMS (FAB) m/z
[M+H]+ calcd for C20H30N4O: 343.2492, found 343.2481.
N-(2-(6-(2-amino-1H-imidazol-5-yl)hexanamido)ethyl)-4-pentyl-
benzamide (23): A vial (23ꢂ85 mm) was charged with 16 (0.095 g,
0.16 mmol) and Pd/C (0.024 g, 0.02 mmol) in anhydrous THF
(2 mL). The resulting solution was first flushed with H2 for 5 min,
and then stirred under 1 atm H2 for 12 h. The mixture was filtered
through Celite, and the solvent was evaporated in vacuo. The
crude carboxylic acid was reacted with 17 (0.063 g, 0.27 mmol),
EDC·HCl (0.052 g, 0.27 mmol), HOBt (0.046 g, 0.27 mmol) and DIEA
(0.070 g, 0.54 mmol) in DMF (2 mL), and the mixture was stirred at
RT as described for the synthesis of 22. Deprotection of the crude
product with TFA (0.5 mL, 6.53 mmol) in CH2Cl2 (2 mL) and purifica-
tion by column chromatography (CH2Cl2/MeOH (sat. NH3), 20:1!
4:1) afforded the desired product 23 as a white solid (0.040 g, 61%
N-(3-(5-(2-Amino-1H-imidazol-5-yl)pentylamino)-3-oxopropyl)-4-
pentylbenzamide (21): A vial (23ꢂ85 mm) was charged with 13
(0.2 g, 0.4 mmol) and anhydrous THF (4 mL), and the solution was
treated with Pd/C (0.043 g, 0.04 mmol). The resulting solution was
first flushed with H2 for 5 min, and then stirred under 1 atm H2 for
12 h. The mixture was filtered through Celite, and the solvent was
evaporated in vacuo. The crude primary amine was added to a solu-
tion of 19 (0.053 g, 0.2 mmol) in DMF (2 mL) at RT. The solution
was treated with EDC (0.077 g, 0.4 mmol), HOBt (0.068 g, 0.4 mmol)
and DIEA (0.105 g, 0.8 mmol), and then stirred at RT for 12 h. The
reaction was diluted with H2O (3 mL) and EtOAc (3 mL), and the
aqueous phase was extracted with EtOAc (3ꢂ3 mL). The combined
organic extracts were washed with H2O (3 mL) and brine (3 mL),
dried over Na2SO4, filtered and concentrated in vacuo. The crude
product was redissolved in CH2Cl2 (2 mL), treated with TFA
(0.5 mL), and stirred at RT for 12 h. The solvent was evaporated in
vacuo, and the residue was purified by column chromatography
(CH2Cl2/MeOH (sat. NH3), 20:1!4:1) to afford desired product 21
as a pale yellow solid (0.065 g, 95% over three steps): 1H NMR
(400 MHz, CD3OD): d=7.77 (d, J=8.4 Hz, 2H), 7.27 (d, J=8.0 Hz,
2H), 6.46 (s, 1H), 3.70 (t, J=6.8 Hz, 2H), 3.23 (t, J=6.8 Hz, 2H), 2.67
(t, J=6.4 Hz, 2H), 2.62 (t, J=7.6 Hz, 2H), 2.39 (t, J=7.6 Hz, 2H),
1.54 (m, 6H), 1.31 (m, 6H), 0.87 ppm (t, J=7.2 Hz, 3H); 13C NMR
(100 MHz, CD3OD): d=174.8, 170.4, 148.6, 148.4, 132.4, 129.7,
128.8, 128.6, 109.6, 41.0, 37.7, 36.8, 36.6, 32.6, 32.2, 29.6, 28.9, 27.3,
25.3, 23.6, 14.5 ppm; IR (neat): n˜ =3288, 2931, 2857, 1680, 1636,
1542, 1504, 1439, 1307, 761 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=205,
226 nm; HRMS (FAB) m/z [M+H]+ calcd for C23H35N5O2: 414.2864,
found 414.2855.
1
over three steps): H NMR (400 MHz, CD3OD): d=7.76 (d, J=8.4 Hz,
2H), 7.28 (d, J=8.4 Hz, 2H), 6.46 (s, 1H), 3.55 (m, 4H), 2.64 (t, J=
8.0 Hz, 2H), 2.41 (t, J=7.6 Hz, 2H), 2.32 (t, J=7.6 Hz, 2H), 1.61 (m,
6H), 1.32 (m, 6H), 0.88 ppm (t, J=6.8 Hz, 3H); 13C NMR (100 MHz,
CD3OD): d=177.7, 170.6, 148.6, 148.5, 132.7, 129.7, 128.9, 128.6,
109.7, 40.8, 40.6, 36.8, 36.4, 32.6, 32.2, 29.4, 28.9, 26.6, 25.2, 23.6,
14.5 ppm; IR (neat): n˜ =3251, 3148, 2925, 2854, 1679, 1633, 1540,
1503, 1403, 1303 cmꢀ1; UV/Vis (CH2Cl2): lmax (e)=229 nm; HRMS
(FAB) m/z [M+H]+ calcd for C23H35N5O2: 414.2864, found 414.2855.
Biological screening
General: MRSA (ATCC # BAA-44) and MDRAB (ATCC # BAA-1605)
were obtained from the American Type Culture Collection (ATCC).
Imipenem monohydrate was purchased from US Pharmacopeial
Convention (USP; # 1337809), penicillin G and oxacillin sodium salt
were purchased from Sigma–Alrich (# P3032) and TCI (# O0353), re-
spectively. Mueller–Hinton broth (MHB) was made using materials
from Becton, Dickinson and Co. (BBL beef extract: # 21230; Difco
soluble starch: # 217820) and MP Biomedicals (casein hydrolysate:
# 101290) using the following procedure: Deionized water (1 L)
was mixed with beef extract (32 g) and soluble starch (1.5 g).
Casein hydrolysate (17.5 g) was then added, and the pH was ad-
justed to 7.4 at RT with 10n NaOH. The resulting solution was au-
toclaved at 1208C for 15 min.
Dose–response curves of lead compounds in MRSA (S14) and
MDRAB (S16) biofilm inhibition assays, along with growth curve
analysis of lead compounds against both MRSA and MDRAB (S18)
are available in the Supporting Information.
6-(2-Amino-1H-imidazol-5-yl)-N-(4-pentylphenyl)hexanamide
(22): A vial (23ꢂ85 mm) was charged with 16 (0.104 g, 0.18 mmol)
and Pd/C (0.024 g, 0.02 mmol) in anhydrous THF (2 mL). The result-
ing solution was first flushed with H2 for 5 min, and then stirred
under 1 atm H2 for 12 h. The mixture was filtered through Celite,
and the solvent was evaporated in vacuo. The crude carboxylic
acid was reacted with 4-pentylaniline (0.048 g, 0.29 mmol), EDC
(0.056 g, 0.29 mmol), HOBt (0.050 g, 0.29 mmol) and DIEA (0.076 g,
0.59 mmol) in DMF (2 mL), and the mixture was stirred at RT ac-
cording to procedure described for 21. Deprotection of the crude
product with TFA (0.5 mL, 6.53 mmol) in CH2Cl2 (2 mL) and purifica-
tion by column chromatography (CH2Cl2/MeOH (sat. NH3), 20:1!
4:1) afforded desired product 22 as a yellow solid (0.012 g, 26%
Inhibition assay protocols: Inhibition assays were performed by
taking overnight cultures of MRSA or MDRAB and subculturing at
an OD600 value of 0.01 into tryptic soy broth with a 0.5% glucose
supplement (TSBG) for MRSA or Luria–Bertani (LB) media for
MDRAB. Stock solutions of predetermined concentrations of test
compound were prepared in the resulting bacterial suspension,
and aliquots (100 mL) of stock solution were plated in a 96-well
format. Plates were covered, sealed with GLAD Press’n Seal, and in-
cubated under stationary conditions at 378C for 24 h. The media
was then discarded, and the plates were washed thoroughly with
water. Each well was stained with 0.1% solution of crystal violet
(110 mL) at RT for 30 min. After thoroughly washing with water
again, the remaining stain was dissolved in 95% EtOH (200 mL),
and an aliquot of the solution (125 mL) was transferred to corre-
sponding wells of a polystyrene microtiter dish. Biofilm inhibition
was quantified by measuring the OD540 value of each well. Blank
wells were employed as background controls.
1
over three steps): H NMR (400 MHz, CD3OD): d=7.77 (d, J=8.4 Hz,
2H), 7.27 (d, J=8.0 Hz, 2H), 6.46 (s, 1H), 3.70 (t, J=6.8 Hz, 2H),
3.23 (t, J=6.8 Hz, 2H), 2.67 (t, J=6.4 Hz, 2H), 2.62 (t, J=7.6 Hz,
2H), 2.39 (t, J=7.6 Hz, 2H), 1.54 (m, 6H), 1.31 (m, 6H), 0.87 ppm (t,
J=7.2 Hz, 3H); 13C NMR (100 MHz, CD3OD): d=174.8, 170.4, 148.6,
148.4, 132.4, 129.7, 128.8, 128.6, 109.6, 41.0, 37.7, 36.8, 36.6, 32.6,
32.2, 29.6, 28.9, 27.3, 25.3, 23.6, 14.5 ppm; IR (neat): n˜ =3308, 3156,
2959, 2928, 2856, 1679, 1598, 1536, 1414, 1384, 1180, 1146, 1073,
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C. Melander et al.
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Broth microdilution method for antibiotic resensitization: MHB was
inoculated (5ꢂ105 CFUmLꢀ1) with either MRSA or MDRAB. The re-
sulting bacterial suspension was aliquoted (4 mL) into culture
tubes, and test compound (from DMSO stock solution) was added
to give the final concentration to be tested. Bacteria not treated
with the test compound served as a control. After sitting for
30 min at RT, 1 mL of each sample was transferred to a new culture
tube, and the appropriate antibiotic (oxacillin and penicillin G
sodium salt for MRSA/imipenem for MDRAB) was added from
a 128 mgmLꢀ1 water stock solution to give a concentration of
128 mgmLꢀ1. Rows 2–12 of a 96-well microtiter plate were filled
with 100 mL/well from the remaining 3 mL bacterial subcultures, al-
lowing the concentration of compound to be kept uniform
throughout the antibiotic dilution procedure. After standing for
10 min, the samples containing antibiotic were aliquoted (200 mL)
into the corresponding first-row wells of the microtiter plate.
Row 1 wells were mixed 6–8 times, and then 100 mL were trans-
ferred to row 2. Row 2 wells were mixed 6–8 times, and then
100 mL were transferred from row 2 to row 3. This procedure was
repeated to serially dilute the rest of the rows of the microtiter
plate, with the exception of the final row, to which no antibiotic
was added. The plate was sealed with GLAD Press’n Seal and incu-
bated under stationary conditions at 378C. After 16 h, minimum in-
hibitory concentration (MIC) values were recorded as the lowest
concentration of antibiotic at which no visible growth of bacteria
was observed.
program is administered by the US Department of the Army; the
US Army Medical Research Acquisition Activity (820 Chandler
Street, Fort Detrick, MD 21702-5014, USA) is the awarding and
administering acquisition office. The content of this manuscript
does not necessarily reflect the position or policy of the US Gov-
ernment, and no official endorsement should be inferred.
Keywords: 2-aminoimidazoles · antibiotics · bacterial biofilms ·
drug-resistant bacteria · resensitization
[1] a) K. Honey, J. Clin. Invest. 2009, 119, 2452–2454; b) D. M. Morens, G. K.
Flokers, A. S. Fauci, Nature 2004, 430, 242–249.
[2] a) A. J. Alanis, Arch. Med. Res. 2005, 36, 697–705; b) B. Spellberg, R.
Guidos, D. Gilbert, J. Bradley, H. W. Boucher, W. M. Scheld, J. G. Bartlett,
J. Edwards, Clin. Infect. Dis. 2008, 46, 155–164.
[3] a) R. P. Wenzel, M. B. Edmont, N. Engl. J. Med. 2000, 343, 1961–1963;
b) P. C. Appelbaum, Clin. Microbiol. Infect. 2006, 12, 3–10; c) J. S.
Hawley, C. K. Murray, M. E. Griffith, M. L. McElmeel, L. C. Fulcher, D. R.
Hospenthal, J. H. Jorgensen, Antimicrob. Agents Chemother. 2007, 51,
376–378.
[4] E. H. Eiland III, D. Gatlin, J. Pharm. Pract. 2008, 21, 313–318.
[5] R. M. Klevens, et al., J. Am. Med. Assoc. 2007, 298, 1763–1771.
[6] F. Perez, A. M. Hujer, K. M. Hujer, B. K. Decker, P. N. Rather, R. A. Bonomo,
Antimicrob. Agents Chemother. 2007, 51, 3471–3484.
[7] J. S. Dickschat, Nat. Prod. Rep. 2010, 27, 343–369.
[8] T. C. Mah, G. A. O’Toole, Trends Microbiol. 2001, 9, 34–39.
[9] T. B. Rasmussen, M. Givskov, Int. J. Med. Microbiol. 2006, 296, 149–161.
[10] a) R. M. Donlan, J. W. Costerton, Clin. Microbiol. Rev. 2002, 15, 167–193;
b) D. J. Musk Jr., P. J. Hergenrother, Curr. Med. Chem. 2006, 13, 2163–
2177.
Checkerboard assay: MHB was inoculated with MRSA (5ꢂ
105 CFUmLꢀ1), and 100 mL were distributed into each well of a 96-
well plate except well 1A. Inoculated MHB (200 mL) containing test
compound (at 2ꢂ the highest concentration being tested) was
added to well 1A, and 100 mL of the same sample were placed in
each of wells 2A–12A. Column A wells were mixed 6–8 times, and
then 100 mL were withdrawn and transferred to column B. Col-
umn B wells were mixed 6–8 times, followed by a 100 mL transfer
to column C. This procedure was repeated to serially dilute the rest
of the columns of the plate up to column G (column H was not
mixed to allow the MIC of antibiotic alone to be determined). Ino-
culated media (100 mL) containing antibiotic at two-times the high-
est concentration being tested was placed in wells A1–H1 (row 1)
and serially diluted in the same manner to row 11 (row 12 was not
mixed to allow the MIC of compound alone to be determined).
The plates were incubated for 16 h at 378C. The MIC values of
both compound and antibiotic in the combination were recorded,
as well as the MIC values of compound alone (row 12) and antibi-
otic alone (column H). The SFIC values were calculated as follows:
SFIC=FICCompd +FICAntibiotic, where FICCompd is the MIC of the com-
pound in the combination/MIC of the compound alone, and FI-
CAntibiotic is the MIC of the antibiotic in the combination/MIC of the
antibiotic. The combination is considered synergistic when the
SFIC value is ꢂ0.5, indifferent when the SFIC value is >0.5 but
<2, and antagonistic when the SFIC is ꢃ2.
[11] D. Davies, Nat. Rev. Drug Discovery 2003, 2, 114–122.
[12] N. Fusetani, Nat. Prod. Rep. 2004, 21, 94–104.
[13] a) J. J. Richards, R. W. Huigens, T. E. Ballard, A. Basso, J. Cavanagh, C.
Melander, Chem. Commun. 2008, 1698–1700; b) J. J. Richards, T. E. Bal-
lard, C. Melander, Org. Biomol. Chem. 2008, 6, 1356–1363; c) R. W. Hui-
gens, G. Parise, J. J. Richards, T. E. Ballard, W. Zeng, R. Deora, C. Meland-
er, J. Am. Chem. Soc. 2007, 129, 6966–6967.
[14] S. A. Rogers, C. Melander, Angew. Chem. 2008, 120, 5307–5309; Angew.
Chem. Int. Ed. 2008, 47, 5229–5231.
[15] S. Reyes, R. W. Huigens, Z. Su, M. L. Simon, C. Melander, Org. Biomol.
Chem. 2011, 9, 3041–3049.
[16] A. E. Clatworthy, E. Pierson, D. T. Hung, Nat. Chem. Biol. 2007, 3, 541–
548.
[17] J. K. Klitgaard, M. N. Skov, B. H. Kallipolitis, H. J. Kolmos, J. Antimicrob.
Chemother. 2008, 62, 1215–1221.
[18] R. J. Worthington, C. A. Bunders, C. S. Reed, C. Melander, ACS Med.
Chem. Lett. 2012, 3, 357–361.
[19] Z. Su, S. A. Rogers, W. S. McCall, A. C. Smith, S. Ravishankar, T. Mullikin,
C. Melander, Org. Biomol. Chem. 2010, 8, 2814–2822.
[20] Z. Su, L. Peng, R. J. Worthington, C. Melander, ChemMedChem 2011, 6,
2243–2251.
[21] Z. Su, L. Peng, C. Melander, Tetrahedron Lett. 2012, 53, 1204–1206.
[22] S. A. Rogers, J. D. Bero, C. Melander, ChemBioChem 2010, 11, 396–410.
[23] G. A. O’Toole, R. Kolter, Mol. Microbiol. 1998, 30, 295–304.
[24] T. E. Ballard, J. J. Richards, A. L. Wolfe, C. Melander, Chem. Eur. J. 2008,
14, 10745–10761.
Acknowledgements
[25] G. Orhan, A. Bayram, Y. Zer, I. Balci, J. Clin. Microbiol. 2005, 43, 140–143.
[26] B. E. Love, E. G. Jones, J. Org. Chem. 1999, 64, 3755–3756.
The authors thank the US Department of Defense (DoD) for sup-
port of this work through the Defense Medical Research and De-
velopment Program (DMRDP) (W81XWH-11-2-0115). The DMRDP
Received: July 17, 2012
Published online on && &&, 0000
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FULL PAPERS
Modulating resistance: 4,5-Disubstitut-
ed 2-aminoimidazole triazole amide (2-
AITA) conjugates were discovered as
MRSA and MDRAB biofilm modulators,
which also suppress MRSA resistance to
oxacillin. Further structure–activity rela-
tionship studies identified a 2-aminoimi-
dazole diamide (2-AIDA) conjugate with
significantly increased resensitization ac-
tivity without compromising the anti-
biofilm activity.
Z. Su, A. A. Yeagley, R. Su, L. Peng,
C. Melander*
&& – &&
Structural Studies on 4,5-
Disubstituted 2-Aminoimidazole-
Based Biofilm Modulators that
Suppress Bacterial Resistance to b-
Lactams
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