Discovery of Potent Inhibitors of Streptococcus mutans Biofilm with Antivirulence Activity

Article abstract of DOI:10.1021/acsmedchemlett.0c00373

Dental caries is a bacterial infectious disease characterized by demineralization of the tooth enamel. Treatment of this disease with conventional antibiotics is largely ineffective as the cariogenic bacteria form tenacious biofilms that are resistant to such treatments. The main etiological agent for dental caries is the bacterium Streptococcus mutans. S. mutans readily forms biofilms on the tooth surface and rapidly produces lactic acid from dietary sucrose. Glucosyl transferases (Gtfs) secreted by S. mutans are mainly responsible for the production of exopolysaccharides that are crucial for the biofilm architecture. Thus, inhibiting S. mutans' Gtfs is an effective approach to develop selective biofilm inhibitors that do not affect the growth of oral commensals. Herein, we report a library of 90 analogs of the previously identified lead compound, G43, and exploration of its structure activity relationships (SAR). All compounds were evaluated for the inhibition of S. mutans biofilms and bacterial growth. Selected compounds from this library were further evaluated for enzyme inhibition against Gtfs using a zymogram assay and for growth inhibition against oral commensal bacterial species such as Streptococcus gordonii and Streptococcus sanguinis. This study has led to the discovery of several new biofilm inhibitors with enhanced potency and selectivity. One of the leads, IIIF1, showed marked reduction in buccal, sulcal, and proximal caries scores in a rat model of dental caries.

Full text of DOI:10.1021/acsmedchemlett.0c00373

pubs.acs.org/acsmedchemlett
Letter
Discovery of Potent Inhibitors of Streptococcus mutans Biofilm with
Antivirulence Activity
Bhavitavya Nijampatnam,⊥ Parmanand Ahirwar,⊥ Piyasuda Pukkanasut, Holly Womack, Luke Casals,
Hua Zhang, Xia Cai, Suzanne M. Michalek, Hui Wu,* and Sadanandan E. Velu*
Cite This: ACS Med. Chem. Lett. 2021, 12, 48−55
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ABSTRACT: Dental caries is a bacterial infectious disease
characterized by demineralization of the tooth enamel. Treatment
of this disease with conventional antibiotics is largely ineffective as
the cariogenic bacteria form tenacious biofilms that are resistant to
such treatments. The main etiological agent for dental caries is the
bacterium Streptococcus mutans. S. mutans readily forms biofilms on
the tooth surface and rapidly produces lactic acid from dietary
sucrose. Glucosyl transferases (Gtfs) secreted by S. mutans are
mainly responsible for the production of exopolysaccharides that
are crucial for the biofilm architecture. Thus, inhibiting S. mutans’
Gtfs is an effective approach to develop selective biofilm inhibitors
that do not affect the growth of oral commensals. Herein, we report a library of 90 analogs of the previously identified lead
compound, G43, and exploration of its structure activity relationships (SAR). All compounds were evaluated for the inhibition of S.
mutans biofilms and bacterial growth. Selected compounds from this library were further evaluated for enzyme inhibition against Gtfs
using a zymogram assay and for growth inhibition against oral commensal bacterial species such as Streptococcus gordonii and
Streptococcus sanguinis. This study has led to the discovery of several new biofilm inhibitors with enhanced potency and selectivity.
One of the leads, IIIF1, showed marked reduction in buccal, sulcal, and proximal caries scores in a rat model of dental caries.
KEYWORDS: Dental caries, Streptococcus mutans, biofilm, glucosyl transferases, SAR, in vivo
washes can increase blood pressure due to the damage caused
ental caries is considered to be a major health concern
1
Dworldwide. Streptococcus mutans (S. mutans) is the main to oral microbiota that have the aptitude to relax blood
vessels.12 In addition, a significant correlation exists between
poor oral health and an increased risk for cardiovascular
diseases.13 Thus, there is an unmet need to develop innovative
approaches to combat the persistent pathogenic oral biofilms.
In order to preserve the natural oral bacterial flora, we sought
to develop nonbactericidal agents that can selectively inhibit
the cariogenic biofilms.
etiological agent of dental caries.2,3 In addition to its ability to
adhere to tooth and form biofilm, S. mutans’ potential to
initiate dental caries also stems from its ability to create and
thrive in an acidic oral microenvironment.4−6 Through the
function of its glucosyl transferases (Gtfs), namely GtfB, GtfC,
and GtfD, S. mutans metabolizes dietary sucrose into water-
insoluble and soluble glucans.7 GtfB synthesizes water-
insoluble glucans and GtfC synthesizes both water-insoluble
and soluble glucans, whereas GtfD synthesizes only water-
soluble glucans.8,9 These exopolymeric glucans play an
important role in mediating the irreversible attachment of S.
mutans to the tooth surface. Glucans also serve as an
extracellular matrix, shielding the bacteria from the host’s
immune responses, mechanical stress, and antimicrobial
agents.10
Several previous studies have validated Gtfs as potential
targets for the development of therapeutic agents that can
selectively inhibit cariogenic biofilms.14,15 Mutants defective in
genes coding for GtfB and GtfC cause markedly reduced levels
of smooth surface caries lesions as compared to parental S.
mutans.16 Polyphenols17−20 that include catechins, flavonoids,
proanthocyanidin oligomers, and other plant-derived analogs21
and synthetic small molecules22 have been found to display
There are several approaches available for the treatment of
dental caries such as the use of fluoride in toothpaste and the
use of antimicrobial mouthwashes. The removal of bacteria by
brushing demands frequent repetition due to the rapid
recolonization of tooth surfaces. Mouthwashes lack selectivity
affecting both pathogenic and commensal species alike.11
Recent studies have suggested that the use of such mouth-
Received: July 7, 2020
Accepted: November 25, 2020
Published: December 7, 2020
https://dx.doi.org/10.1021/acsmedchemlett.0c00373
© 2020 American Chemical Society
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modest antibiofilm activities by modulating the expression or
the activity of Gtfs. However, the selectivity of these
compounds for biofilm inhibition opposed to growth inhibition
remains to be determined, and their biofilm inhibitory
potencies are low.
We have recently reported a novel Gtf inhibitor G43 (Figure
1A) identified by in-silico screening using the reported GtfC X-
of 90 analogs in order to optimize its activity and to identify
additional derivatives that are suitable for preclinical develop-
ment.
We designed this library starting from a series of carboxylic
acids (IA‑J) and the amine derivatives (II1‑9) as shown in
Figure 2. The left side modifications (R1) included 5-
nitroindole, 5-methoxyindole, 5-nitrobenzofuran, 3-quinolyl,
2-quinolyl, α-naphthyl, β-naphthyl, the 4-biphenyl group, and
the right side modifications (R2) included the −CONH2 and
−COOMe groups at 2-, 3-, and 4- positions and a −CH2NH2
group at the 2-position of the phenyl ring and an unsubstituted
phenyl ring. This library was synthesized in one step by an
established amide coupling reaction using N-ethyl-N′-(3-
(dimethylamino)propyl)carbodiimide (EDC) and N,N-di-
methyl aminopyridine (DMAP) in dichloromethane
(CH2Cl2). This procedure is amenable for the solution phase
parallel synthesis as it takes place under mild conditions and
the byproducts are removable by aqueous workup. It produced
the expected amide products (IIIA1‑J8) in yields ranging from
26 to 99% (Table 1). The Boc protecting group present in
compounds IIIA8‑J8 was removed by treatment with trifluoro-
acetic acid (TFA) to generate the aminomethyl derivatives
IIIA9‑J9. Out of the 90 library compounds, 15 indole derivatives
(IIIB1‑9 and IIIE4‑9) were produced in lower yields and were
sparingly soluble in dimethyl sulfoxide (DMSO) and other
solvents, making their characterization and analysis difficult.
The remaining 75 library products were subjected to purity
determinations by LC-MS, NMR, and high-resolution mass
spectroscopy (HRMS). Complete spectroscopic analyses using
1H NMR, 13C NMR, and HRMS were carried out on a random
sampling of ∼50% of the library (47 compounds). NMR purity
determinations using hexamethyl disiloxane (HMDSO) as an
internal standard were carried out on selected 10% of the
library (9 samples, Table 1 and Supporting Information).
Figure 1. (A) Chemical structure of G43. (B) Fluorescent
microscopy images of S. mutans UA159 biofilms with G43 treatment
using serial dilutions. Panel I: Viable bacterial cells within the biofilm
were stained with 2.5 μM Syto9 (green). Panel II: Dextran-conjugated
cascade blue labeled exopolysaccharides within S. mutans biofilms.
ray crystal structure as target.23 G43 inhibited S. mutans
biofilm in a dose dependent manner with an IC50 value of 16.7
μM, but it did not inhibit the growth of S. mutans or other oral
commensal species up to 200 μM, indicating that it is a
selective biofilm inhibitor (Figure 1B).23 We have now
completed the SAR studies on G43 by generating a library
Figure 2. Synthesis of G43 analogs.
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Table 1. Characterization of G43 Analogs IIIA2‑J9 and Their Biofilm Inhibition Profiles
a
b
1
1
Fully characterized with H NMR, 13C NMR, and HRMS. Purity determined to be above 90% by H NMR internal standard measurements
c
d
e
f
using HMDSO as standard. Unable to characterize due to poor solubility. Unable to collect data due to poor solubility. Solubility in water. Not
determined. Insoluble. Values represent the means standard deviations from three independent experiments. Reaction did not work. TFA
salt.
g
h
i
*
The structural modifications of G43 were guided by its
docking model within the GtfC active site generated using
FlexX/LeadIT (Figure 3).24,25 According to this model G43
occupies the same space as the ligand (acarbose) in the
reported X-ray crystal structure and is within the H-bonding
distance from the three critical active site catalytic residues,
Glu515, Asp477, and Asp588.26 The ortho amide group of
G43 that is critical for its activity was found to be making
direct H-bonding interactions with two of these residues,
Glu515 and Asp477 (Figure 3).
We chose to incorporate different bicyclic ring systems in
the place of the benzothiophene ring (left) and different
substituents on the phenyl ring (right) of G43 using a
combination of both rational and classical medicinal chemistry
approaches. For example, the primary amide group on the
phenyl ring of G43 holds protons weakly. Amines, on the other
hand, are strong proton acceptors due to the higher availability
of the lone pair of electrons on the nitrogen atom to accept
acidic hydrogens. This small manipulation in compound IIIA9
improves the predicted binding energy from −32 to −39 kJ/
mol (Figure 4). This change in the functional group from
amide to amine group improved the interactions with Asp588
due to the increase in rotation and flexibility gained from the
change in hybridization of the amide carbon atom from sp2 to
sp3, contributing to the overall improved score.
The S atom within the left ring of G43 is predicted to have
no specific interactions with any of the active site residues.
Changing the S to NH in compound IIIB1 resulted in the
binding of the newly added NH with the negatively charged
Asp909 in the proximity (Figure 4). This modification also
altered the bond angles within the lead molecule, which
produces additional interactions as reflected by the improved
binding energy of −37 kJ/mol. This derivative also interacts
with the residues Glu515 and Asp588, justifying its improved
binding score. As an extension of these studies, we have
conducted docking studies to explore the inclusion of bicyclic
systems such as the quinoline ring as shown in compound
IIIF1, which was able to engage all three key residues, Glu515,
Asp 477, and Asp 588 and had an improved binding energy of
−37 kJ/mol.
We evaluated the effects of all of the library products on S.
mutans growth and viability to determine the selectivity toward
inhibiting the biofilm versus bacterial growth. Consistent with
our hypothesis, no significant difference in S. mutans cell
viability was observed between the control group and treated
groups for all library products up to 100 μM, suggesting that
the compounds are not bactericidal toward S. mutans. Potent
selective biofilm inhibitors were then analyzed with serial
dilutions to determine accurate biofilm inhibition IC50 values
(Table 1). The left side modification of G43 resulted in a
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the activity, while changing it to the p-position (IIIA3) nullified
the activity. These observations were consistent with our
docking model predicting key interactions of the o-CONH2
group with active site residues. However, substitution of the o-
CONH2 group with o-COOMe groups produced a different
trend. The o-COOMe group (IIIA4) nullified the activity, m-
COOMe (IIIA5) was less active, and p-COOMe (IIIA6) was
more active than G43. The effect of replacement of o-CONH2
with o-CH2NH2 can be seen in IIIA9. Contrary to the
prediction by the model, the IC50 value of IIIA9 was 106.2
μM compared to 16.7 μM for the G43. Interestingly, the Boc
protected intermediate (IIIA8) was found to be more potent
than the free amine counterpart (IIIA9) with an IC50 value of
51.5 μM.
Several key SAR observations could be drawn for the
structural modifications to either ends of G43 from the average
biofilm IC50 value for each series (Figure 5). While a clear
trend is not apparent when comparing benzothiophene and
benzofuran series, an overall trend can be deduced. The
average biofilm inhibitory activity is comparable, exhibiting
131 μM and 121 μM for benzothiophene (IIIA1‑9) and
benzofuran (IIIC1‑9) series, respectively. The indolyl (IIIB1‑9
)
and 2-quinolinyl (IIIG1‑9) series of compounds offer a
comparison of the ring size and its effect on the biofilm
inhibition. As previously mentioned the indole series were
insoluble. While the evaluated indole derivatives had no effect
on the biofilm, the 2-quinolinyl derivatives exhibited micro-
molar inhibition, with the average IC50 being 132 μM. The
attachment point of the left aromatic ring and its effect on
activity can be observed in the 3-quinolinyl (IIIF1‑9) and 2-
quinolinyl (IIIG1‑9) series, where the substituent comes off the
3-position and 2-position, respectively, and the β-naphthalene
(IIIH1‑9) and α-naphthalene (IIII1‑9) series, where the
substituent comes off the 2-position and 1-position,
respectively. With the exception of IIIG3, IIIG4, and IIIG5 the
2-quinolines were less potent than their 3-quinoline counter-
parts. Similarly, the α-naphthalene (IIII1‑9) series were less
potent compared to the β-naphthalene (IIIH1‑9) series.
Figure 3. Docking model of G43 (green sticks) superposed on the
crystal structure of acarbose (pink line) within the GtfC catalytic site.
Key active site interactions are depicted by displaying residue chains
(blue sticks).
When the o-CONH2 group was removed in the IIIA7‑J7
series, to have an unsubstituted benzene ring on the right side,
the activity was nullified in all examples up to 300 μM,
highlighting the importance of the o-CONH2 group. The
overall trends in average IC50 values revealed that the primary
amide regiochemistry is also crucial for the activity of the
compound. Compared to the o-position, the placement of this
functional group in the m-position marginally increased
potency. The 3-quinolinyl analog IIIF2 in particular had an
improved IC50 value of 8.6 μM. On the other hand, the p-
CONH2 group almost consistently reduced the activity with
the exception of IIID3, IIIG3, and IIIH3. The primary amide
group was replaced with a methyl ester functionality in series
III4‑6. Interestingly, this moiety at the o-position did not serve
to increase the potency and in several instances nullified the
activity of the compounds, as seen in IIIA4, IIID4, IIIH4, and
IIIJ4. Remarkably, this functional group in the m- and p-
positions was able to give the right combination of interactions
to elevate the potency. For example, the compound IIIC5, a 5-
nitrobenzofuran derivative with an m-COOMe group,
produced the best IC50 value of 2.7 μM, making it the most
potent compound identified from this library. Through the
SAR studies, we have identified several new analogs that are
either equally or more potent than G43 (Figure 6A). Docking
models of these compounds indicated that their binding modes
Figure 4. Chemical structures and binding energies of G43 and a few
of its derivatives.
number of biofilm inhibitors with IC50 values ranging from
15.3 μM to 193.3 μM with considerable variations related to
specific structural modifications. For example, removal of the
nitro group (IIID1) and substitution of the ring with naphthyl
(IIIH1 and IIII1) and biphenyl rings (IIIJ1) resulted in decrease
in activity. The docking model predicted indole compounds to
have increased interactions with the GtfC active site residues.
However, the indole series were largely insoluble in DMSO
and other solvents making its characterization and evaluation
difficult.
The o-CONH2 group at the right end of G43 was modified
in many ways. Its complete removal (IIIA7‑J7) resulted in total
loss of activity. Changing it to the m-position (IIIA2) decreased
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Figure 5. (A) Average biofilm IC50 values for varying left-side modifications. (B) Average biofilm IC50 values for varying right-side modifications.
The highest tested concentration of 300 μM is used for the average IC50 calculations of the inactive compounds.
Figure 6. (A) Chemical structures of G43 and its more active analogs identified from the SAR studies. (B) Docking models of IIIA6 (yellow), IIIF1
(magenta), IIIC5 (violet), and IIIF2 (gold) in the GtfC active site compared with G43 (green).
are quite similar to what we have observed for G43 with the
exception of IIIF2, which took a slightly different binding
mode. Compounds IIIA6, IIIF1, and IIIC5 engaged at least two
of the three catalytic site residues while IIIF2 was shown to
engage all three residues (Figure 6B).
bands produced. As seen in Figure 8A, there was a definite
decrease in the production of glucans synthesized by GtfC, the
bottom band. There was also a decrease in the upper band in
which GtfB and GtfD remain unseparated, suggesting that the
compounds act upon at least two, if not all three Gtfs.
Compounds IIIA6, IIIA8, IIIF1, IIIF2, and IIIF8 along with two
control compounds G43 and G16,23 showed a higher potency
in the biofilm assay and also appeared to be more potent in the
zymogram assay. These results suggest that the inhibitory
effect seen on the S. mutans biofilms is through the inhibition
of S. mutans Gtfs.
Based on the SAR studies and the zymogram results, we
selected compound IIIF1 for further evaluation in an animal
model of dental caries. This selection was based on its potency,
selectivity, novelty of the chemical structure, and potential for
future preclinical development. Other optimized compounds
such as IIIC5 or IIIA6 with better biofilm inhibition were not
pursued due to the presence of the undesirable NO2 group in
their structure. Prior to the animal studies, the bactericidal
It is important to note that although in-silico screening and
docking studies were performed against GtfC, significant
inhibition of both GtfB and GtfC is expected for our inhibitors
as both these targets have a very similar amino acid
composition (93.61% sequence identity), both are subject to
the same regulatory processes, and the genes encoding GtfB
and GtfC lie close to each other.27 The structural similarity
between GtfB and GtfC is shown in the overlay of the
homology model of chain A of GtfB on the crystal structure of
chain A of GtfC (Figure 7A) and almost indentical binding
modes of G43 in the active sites of GtfB and GtfC (Figure 7B).
We have subjected several of our key compounds to a
reported zymogram assay28 that offers a qualitative observation
of the inhibition of Gtfs through the intensity of the glucan
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and demonstrated that they do not affect the growth at 100
μM (Figure 8B).
The effect of compound IIIF1 on S. mutans colonization and
virulence was evaluated using a rat model of dental caries
(Figure 9).29 Compound G43 was included in these studies for
Figure 7. (A) Overlay of the homology model of the GtfB chain A
(magenta) with the crystal structure of the GtfC chain A (blue) with
G43 bound. (B) Binding modes of G43 in the active site of GtfB
(gold sticks) compared with GtfC (green sticks).
Figure 9. (A) Fluorescent microscopy images of S. mutans UA159
biofilms with its treatment with serial dilutions of IIIF1. Panel I: Viable
bacterial cells within biofilm were stained with 2.5 μM Syto9 (green).
Panel II: Dextran-conjugated cascade blue labeled exopolysaccharides
within S. mutans biofilm. (B) Effect of treatment with G43 or IIIF1 on
the susceptibility of gnotobiotic rats to S. mutans UA159 infection and
dental caries activity. Rats infected starting at 22 days of age and
placed on Diet 305. Rats were sacrificed at 64 days of age (day 43).
No significant differences in the body weights of treated and untreated
rats. No significant difference in CFU/mL for IIIF1 treated and
untreated rats. (C) Caries Scores: buccal and proximal: p < 0.00,
sulcal: p < 0.001. Significant reduction in buccal, sulcal, and proximal
caries scores was observed in animals treated with G43 or IIIF1.
comparison. The biofilm inhibition profile of IIIF1 is presented
in Figure 9A. All rats from the two experimental groups and
from the control (vehicle + infection only) group were
colonized with S. mutans. The bacterial colonization appears to
be reduced in G43 treated rats when compared with the
control group while the novel analog, IIIF1 had no effect on the
bacterial colonization, suggesting that it is less toxic to bacteria
than G43 (Figure 9B). The buccal, sulcal, and proximal surface
caries scores of the treated animals were significantly reduced
in both cases (Figure 9C). These data suggest that both
compounds selectively target virulence factors and Gtfs and
Gtf- mediated biofilm formation, rather than a simple
inhibition of bacterial growth. Furthermore, as observed with
G43,23 rats treated with IIIF1 did not exhibit any weight loss
over the course of the study in comparison with the control
group, suggesting that the compounds are nontoxic to animals.
In conclusion, Gtfs are indispensable virulence factors for
the cariogenesis of S. mutans. We have synthesized a library of
90 derivatives of G43 to study the SAR and have uncovered
several crucial groups and their respective regiochemistry
needed for potent biofilm inhibition. We have identified several
new analogs that are either equally or more potent than G43.
The most active compound, IIIC5 inhibited S. mutans biofilm
with an IC50 value of 2.7 μM. Selected compounds from this
library were further evaluated for enzyme inhibition against
Gtfs using a zymogram assay and for growth inhibition against
Figure 8. (A) Effects of selected compounds on the activity of Gtfs by
zymographic assays, lane-1: DMSO, lane-2: G43, lane-3: G16, lane-4:
IIIA6, lane-5: IIIA8, lane-6: IIIF1, lane-7: IIIF2, and lane-8: IIIF8.
Zymographic assays were performed using SDS-PAGE analysis of Gtfs
from culture supernatants of S. mutans UA159 incubated with vehicle
control DMSO, the compounds 50 μM. (B) Effects of G43 or IIIF1 on
commensal species. S. gordonii, S. sanguinis, and S. mutans were treated
with 100 μM of the compound or DMSO and bacterial growth was
measured at OD470 and normalized to the DMSO control (100%).
The p value is ≤0.05.
activities of IIIF1 and the control compound G43 were further
investigated to rule out the possibility that observed biofilm
inhibition is a result of bactericidal activity and to confirm that
they do not affect the growth of oral commensals. Both
compounds were evaluated against representative commensal
oral bacteria, S. sanguinis and S. gordonii, along with S. mutans,
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oral commensal bacterial species. This study has led to the
discovery of several new biofilm inhibitors with enhanced
potency and selectivity. One of the lead compounds, IIIF1,
showed marked reduction in buccal, sulcal, and proximal caries
scores in a rat model of dental caries.
ACKNOWLEDGMENTS
■
This study was funded by the National Institute of Dental and
Craniofacial Research, National Institutes of Health grants
R21DE028349 and R03DE025058 to Velu, R01DE022350 to
Wu, and F31DE025783 to Nijampatnam.
ASSOCIATED CONTENT
■
ABBREVIATIONS
■
sı
* Supporting Information
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acsmedchemlett.0c00373.
Gtf, glucosyltransferases; S. mutans, Streptococcus mutans; S.
sanguinis, Streptococcus sanguinis; S. gordonii, Streptococcus
gordonii; SAR, structure activity relationship; EDC, N-ethyl-
N′-(3-dimethylaminopropyl)carbodiimide; DMAP, N,N-di-
methyl aminopyridine; TFA, trifluoroacetic acid; DMSO,
dimethyl sulfoxide; HRMS, high resolution mass spectrometry;
LC-MS, liquid-chromatography mass spectrometry; NMR,
nuclear magnetic resonance; HMDSO, hexamethyl disiloxane;
BOC, tert-butyloxy carbonyl; IC50, half maximal inhibitory
concentration; SDS-PAGE, sodium dodecyl sulfate-polyacryla-
mide gel electrophoresis; CFU, colony forming unit
Spectral characterization, spectra, synthetic procedures,
and biological protocols (PDF)
AUTHOR INFORMATION
■
Corresponding Authors
Sadanandan E. Velu − Department of Chemistry, University of
Alabama at Birmingham, Birmingham, Alabama 35294,
United States; orcid.org/0000-0002-0342-2378;
Phone: (503) 418-2090; Email: wuhu@ohsu.edu
Hui Wu − Department of Integrative Biomedical and
Diagnostic Sciences, Oregon Health and Science University,
Portland, Oregon 97239, United States; Phone: (205) 975-
2475; Email: svelu@uab.edu
REFERENCES
■
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Bhavitavya Nijampatnam − Department of Chemistry,
University of Alabama at Birmingham, Birmingham,
Alabama 35294, United States
Parmanand Ahirwar − Department of Chemistry, University
of Alabama at Birmingham, Birmingham, Alabama 35294,
United States
Piyasuda Pukkanasut − Department of Chemistry, University
of Alabama at Birmingham, Birmingham, Alabama 35294,
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Holly Womack − Department of Chemistry, University of
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Luke Casals − Department of Chemistry, University of
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Hua Zhang − Department of Pathology, University of
Alabama at Birmingham, Birmingham, Alabama 35294,
United States
Xia Cai − Department of Microbiology, University of Alabama
at Birmingham, Birmingham, Alabama 35294, United States
Suzanne M. Michalek − Department of Microbiology,
University of Alabama at Birmingham, Birmingham,
Alabama 35294, United States
Complete contact information is available at:
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https://pubs.acs.org/10.1021/acsmedchemlett.0c00373
Author Contributions
⊥B.N. and P.A. contributed equally to this manuscript.
Conceived the idea and designed the experiments: S.E.V.,
H.Wu, and S.M.; Performed the experiments: B.N., P.A., P.P.,
and H.W., L.C., H.Z., and X.C. Drafted and finalized the
manuscript, B.N., S.E.V., and H.Wu.
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Notes
The authors declare no competing financial interest.
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