Optimization of potent inhibitors of P. falciparum dihydroorotate dehydrogenase for the treatment of malaria

Article abstract of DOI:10.1021/ml200143c

Inhibition of dihydroorotate dehydrogenase (DHODH) for P. falciparum potentially represents a new treatment option for malaria, since DHODH catalyzes the rate-limiting step in the pyrimidine biosynthetic pathway and P. falciparum is unable to salvage pyrimidines and must rely on de novo biosynthesis for survival. We report herein the synthesis and structure-activity relationship of a series of 5-(2-methylbenzimidazol-1-yl)-N-alkylthiophene-2-carboxamides that are potent inhibitors against PfDHODH but do not inhibit the human enzyme. On the basis of efficacy observed in three mouse models of malaria, acceptable safety pharmacology risk assessment and safety toxicology profile in rodents, lack of potential drug-drug interactions, acceptable ADME/pharmacokinetic profile, and projected human dose, 5-(4-cyano-2-methyl-1H-benzo[d]imidazol-1-yl) -N-cyclopropylthiophene-2-carboxamide 2q was identified as a potential drug development candidate.

Full text of DOI:10.1021/ml200143c

LETTER
pubs.acs.org/acsmedchemlett
Optimization of Potent Inhibitors of P. falciparum Dihydroorotate
Dehydrogenase for the Treatment of Malaria
Renato T. Skerlj,*,† Cecilia M. Bastos,† Michael L. Booker,† Martin L. Kramer,† Robert H. Barker, Jr.,†
Cassandra A. Celatka,† Thomas J. O’Shea,† Benito Munoz,‡ Amar Bir Sidhu,‡ Joseph F. Cortese,‡
||
||
Sergio Wittlin,§, Petros Papastogiannidis,§, Inigo Angulo-Barturen,^ Maria Belen Jimenez-Diaz,^ and
Edmund Sybertz†
†Genzyme Corporation, 153 Second Avenue, Waltham, Massachusetts 02451, United States
‡Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02141, United States
§Swiss Tropical and Public Health Institute, Socinstrasse 57, CH-4002, Basel, Switzerland
University of Basel, Petersplatz 1, CH-4003, Basel, Switzerland
^Medicines Development Campus, Diseases of the Developing World, GlaxoSmithKline, c/Severo Ochoa 2, 28760 Tres Cantos, Spain
S Supporting Information
b
ABSTRACT: Inhibition of dihydroorotate dehydrogenase (DHODH) for
P. falciparum potentially represents a new treatment option for malaria, since
DHODH catalyzes the rate-limiting step in the pyrimidine biosynthetic
pathway and P. falciparum is unable to salvage pyrimidines and must rely on
de novo biosynthesis for survival. We report herein the synthesis and
structureÀactivity relationship of a series of 5-(2-methylbenzimidazol-1-yl)-N-alkylthiophene-2-carboxamides that are potent
inhibitors against PfDHODH but do not inhibit the human enzyme. On the basis of efficacy observed in three mouse models of
malaria, acceptable safety pharmacology risk assessment and safety toxicology profile in rodents, lack of potential drugÀdrug
interactions, acceptable ADME/pharmacokinetic profile, and projected human dose, 5-(4-cyano-2-methyl-1H-benzo[d]imidazol-1-
yl)-N-cyclopropylthiophene-2-carboxamide 2q was identified as a potential drug development candidate.
KEYWORDS: DHODH, malaria, P. falciparum, drug candidate
alaria remains a major global health burden and is endemic
in 87 countries where 2.5 billion people are at risk.1 While a
with 2e resulted in a sterile cure.10 We had also disclosed the in
vitro activity data and ADME data for two further advanced
analogues 2j and 2q.10 In this letter, we will describe our medicinal
chemistry strategy, structureÀactivity relationship (SAR), and
synthesis leading to compounds 2e, 2j, and 2q. Specifically, we
will describe how we mitigated CYP and hERG inhibition liabilities
of 2e and provide recently generated in vivo data that resulted in
the selection of compound 2q as a potential drug development
candidate (Figure 1).
The SAR was based on the enzymatic PfDHODH activity and
confirmed in a cell-based assay against the 3D7 and Dd2 drug-
sensitive and drug-resistant strains of P. falciparum. In some cases
(Table 2), the compounds appear to be more active in the cell-
based assay than the enzymatic PfDHODH assay since the enzy-
matic assay was run at 12.5 nM, limiting our ability to measure
inhibition in the very low nanomolar ranges. Our medicinal che-
mistry starting point was compound 1d, and the first region that
we investigated was the effect of substitution at the secondary
amide (Table 1). It was clear from the primary and tertiary amides
1a and 1j that a secondary amide was crucial for activity since
both of these compounds were inactive in the PfDHODH enzymatic
M
number of highly effective chemotherapies have been developed
over the years, widespread evolution of resistance has rendered
most to be of limited value.2,3 Moreover, the reduced clinical efficacy
of the frontline artemisinin derivatives emphasizes the urgent
need for new antimalarial drugs.4,5 Given our interest in inves-
tigating the inhibition of novel biological targets, we collaborated
with the Medicines for Malaria Venture on finding small mole-
cule inhibitors of PfDHODH. Inhibition of human DHODH, the
fourth step in the de novo pathway and the rate-limiting step for
the synthesis of pyrimidines, has been shown to be effective in
the clinic for the treatment of rheumatoid arthritis, resulting in the
approval of leflunomide in 1998.6 Unlike the mammalian cell,
the parasite isunable to salvage pyrimidines and depends on the de
novo pathway for the supply of pyrimidines for survival. In recent
years, there have been several reports on the synthesis of potent
and selective inhibitors for PfDHODH as possible new targets for
the treatment of malaria.7 Phillips recently reported the first
example of a PfDHODH inhibitor that was efficacious in a mouse
model for malaria.8 Previously, wereported that the benzimidazole
analogue 1d had improved physicochemical properties and com-
parable activity as compared to the orginal hit identified from a
high throughput screen (Figure 1).9 Recently, we disclosed that
treatment of infected mice in the acute P. berghei efficacy model
Received: June 13, 2011
Accepted: July 10, 2011
Published: July 11, 2011
r
2011 American Chemical Society
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LETTER
assay (IC50 > 30 μM). Another striking observation was the
sensitivity of the PfDHODH activity and cell-based activity to
subtle changes in the steric size of the amide. For instance,
the PfDHODH IC50 values for compounds 1b (Me), 1c (Et), 1d
(n-Pr), and 1h (n-Bu) were 1.08, 0.14, 0.70, and 28.6 μM, an ap-
proximate 200-fold decrease in activity between the Et and the n-Bu
analogues. Although the Et analogue 1c was the most potent of
this series, a moderate enhancement in potency was observed
when the substituent was changed to a c-Pr ring 1f with an IC50 of
0.06 μM. This was verified by the 3D7 and Dd2 IC50 values,
which were 0.08 and 0.09 μM, respectively. These data suggested
that the cyclopropyl group was occupying a defined hydrophobic
pocket, and this was confirmed by an X-ray crystal structure from
the Philips laboratory10 of 2e bound to PfDHODH.10 Additional
evidence that the c-Pr group was occupying a defined hydro-
phobic pocket was provided by the decrease in potency that was
observed as the ring size was gradually increased. For example, in
going from c-Pr 1f to c-pentyl 1i, the potency decreased 40-fold.
Having determined that a secondary amide substituted with a
c-Pr group afforded the optimal potency, we turned our attention
to examine the effect of substitution at the 2-position of the
benzimidazole ring (Table 1). Simple substitution of a methyl
group 1k resulted in comparable potency to the unsubstituted
analogue 1f, with an IC50 of 0.08 vs 0.06 μM, but more importantly,
there was an improvement in in vitro hepatic metabolic stability
based on data in human microsomes (data not shown). Increas-
ing the steric bulk at the 2-position with an ethyl 1l or n-Pr
1m group was not beneficial from either a potency or an
ADME perspective. Moreover, the addition of a polar hydroxyl
group 1n or dimethyl amino group 1p was also detrimental
to activity.
Compounds 1aÀj were prepared as outlined in Scheme 1.
The coupling of 5-bromothiophene-2-carboxylic acid 3a with
benzimidazole in the presence of a catalytic amount of Cu2O and
2-amino-4,6-dihydroxypyrimidine afforded the key intermediate
3c, which underwent DCC coupling with a variety of commer-
cially available amines to afford the secondary amides 1aÀj.
Conversely, compounds 1kÀn and 1p were obtained by Cu(I)-
catalyzed coupling of 5-bromo-N-cyclopropylthiophene-2-car-
boxamide 3b with the corresponding 2-substituted benzimida-
zoles in the presence of catalytic amounts of Cu2O and 4,7-di-
methoxy-1,10-phenathroline.11
The substitution pattern of the thiophene ring was assessed.
The 2,5-substitution pattern was found to be optimal since 2,4-
and 3,4-substitution resulted in a significant loss in potency.
Replacements of the thiophene ring were also examined and
these included meta- and para-substituted phenyl, 2,5-substituted
N-methyl pyrrole, pyrrole, thiazole, furan, and oxazole (data not
shown). None of these replacements resulted in any appreciable
activity other than the 2,5-substituted N-methyl pyrrole, which
was approximately 3-fold less active than the corresponding
thiophene. Although this series was not actively pursued, it was
considered an important backup lead.
Next, we investigated the effect of substitution on the benzi-
midazole ring (Table 2). Simply walking a methyl group around
Figure 1. Structures of compounds 1 and 2.
Table 1. Enzyme Inhibition and Parasite Viability of Compound 1a
compd
R
R1
PfDHODH IC50 (μM)
HsDHODH IC50 (μM)
3D7 IC50 (μM)
Dd2 IC50 (μM)
LC50 (μM)b
1a
1b
1c
1d
1e
1f
H
H
>30
na
>40
>30
na
H
Me
1.08
0.14
0.70
0.68
0.06
0.42
28.6
2.51
>30
>30
>30
>30
>30
>30
>30
>30
>30
na
0.28
0.10
0.47
0.56
0.08
0.41
>20
0.42
0.15
1.10
0.81
0.09
0.44
7.30
5.50
>40
>62
>62
>62
>62
>62
>62
na
H
Et
H
n-Pr
i-Pr
H
H
c-Pr
c-Bu
n-Bu
c-Pentyl
diMe
c-Pr
c-Pr
c-Pr
c-Pr
c-Pr
c-Pr
1g
1h
1i
H
H
H
4.40
>40
na
1j
H
na
1k
1l
Me
Et
0.08 (n = 3)
0.11
0.18
>30
>30
>30
15.1
na
0.09 (n = 3)
0.12
0.39
>5
0.11 (n = 3)
0.18
0.63
>5
>62
>62
>62
na
1m
1n
1o
1p
n-Pr
OH
CF3
NMe2
0.57
>30
0.83
1.71
>62
>62
5.6
na
>1
>1
a Assay conditions reported in ref 10. b LC50 is the lethal concentration required to kill 50% of human renal proximal tubule cells.
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LETTER
Table 2. Enzyme Inhibition, Parasite Viability, and Microsomal Stability of Compound 2a
IC50 (nM)
predicted CLb (mL/min/kg)
compd
R
R1
PfDHODH
HsDHODH
3D7
Dd2
H
M
cLogP
2a
2b
2c
2d
2e
2f
4-Me
39 (n = 4)
10 (n = 4)
22 (n = 4)
10
8
66
3.9
3.9
3.9
3.9
4.7
4.7
4.3
4.3
3.6
4.1
4.2
3.5
3.5
4.1
4.1
4.3
2.9
3.9
4.0
3.5
4.3
3.8
3.5
3.8
3.0
5-Me
56
87
130
>72
>72
>72
43
6-Me
56
33
74
10
6
7-Me
609
143
290
5-OCF3
6-OCF3
5-CF3
22 (n = 4)
7 (n = 4)
9 (n = 4)
7
52 (n = 2)
36 (n = 2)
53 (n = 2)
10
4
41
2g
2h
2i
28
20
28
>72
68
6-CF3
92
56
96
8
4-OMe
4-OCHF2
4-OCH2CHF2
4-F
162
49
109
4
>72
33
2j
44 (n = 6)
19 (n = 6)
26 (n = 6)
4
Me
>30000
2k
2l
28
128
113
na
<4
<4
<4
na
5
na
34 (n = 2)
8 (n = 2)
6 (n = 2)
37
2m
2n
2o
2p
2q
2r
6-F
111
93
113
>72
19
4-Cl
21 (n = 2)
5 (n = 2)
6 (n = 2)
5-Cl
49
78
102
na
4-Br
21 (n = 2)
4 (n = 2)
7 (n = 2)
26
4-CN
40 (n = 9)
7 (n = 4)
10 (n = 4)
<4
na
12
10
5
26
4-NMe2
4-F, 6-Me
4-F, 6-Me
4-Cl, 6-F
4-Cl, 6-F
5-Me, 7-F
5-CF3
181
32
17
25
35
95
19
62
75
10
4
159
17
4
na
2s
2t
>72
>72
42
H
3100
2u
2v
2w
2x
2y
Me
H
>30000
5600
12
8
13
18
60
12
8
7
>72
>72
>72
>72
H
7300
36
12
17
11
8
H
17200
4-F
H
14900
10
a Assay conditions reported in ref 10. b Using microsomes and based on well-stirred model with no correction for microsomal or protein binding.
Scheme 1a
a Reagents: (a) Benzimidazole, Cs2CO3, Cu2O, 2-amino-4,6-dihydroxypyrimidine, PEG, NMP, 160 ꢀC. (b) H2NR1, EDC HCl, HOBt, NMM, CH2Cl2.
3
(c) SOCl2, c-PrNH2. (d) Cs2CO3, Cu2O, 4,7-dimethoxy-1,10-phenanthroline, PEG, DMSO, 110À120 ꢀC. (e) Cs2CO3, Cu2O, quinolin-8-ol, DMSO,
110À120 ꢀC.
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Scheme 2a
a Reagents: (a) (ClCH)2, SOCl2,150 ꢀC, 30 min, MeOH. (b) Pd(OH)2/C, H2, EtOH. (c) Compound 3d, Cs2CO3, Pd2(dba)3, Xantphos, 1,4-dioxane,
80À120 ꢀC. (d) Compound 3d, KOH, BnEt3NCl, DMF, 0 ꢀC to room temperature. (e) SnCl2, HCl (12 M), EtOH. (f) (EtO)3CMe or (MeO)3CH,
reflux. (g) LiOH, MeOH, H2O, 100 ꢀC. (h) SOCl2, c-PrNH2, 1,2-dichloroethane. (i) HCTU, DIPEA, c-PrNH2, DMF. (j) Compound 3d or 5-amino-N-
cyclopropylthiophene-2-carboxamide, K2HPO4, Pd2(dba)3, Ruphos, t-BuOH, molecular sieves 4 Å, 120 ꢀC. (k) TFA, 80 ꢀC, 2 h. (l) DMF, NaH,
BrCH2CH2F.
the ring from the 4- to the 7-position (2aÀd) resulted in an ap-
proximate 2-fold enhancement in activity for analogues 2aÀc as
compared to 1k but an approximate 8-fold reduction in potency
for the 7-methyl analogue 2d, suggesting steric hindrance at the
7-position. This was confirmed by the 5-Me, 7-F analogue 2w
(Table 2), which is isosteric to the 5-Me analogue 2b and had
comparable enzymatic potency. Interestingly, substitution with
electron-withdrawing groups such as CF3 (2g, 2h) and OCF3
(2e, 2f) at the 5- and 6-positions indicated that hydrophobic
groups at the 5-position provided a 2À3-fold enhancement in
potency as compared to 6-substitution. More pronounced was
the difference in cellular activity, for instance, the 3D7 and Dd2
IC50 values were 7 and 9 nM vs 36 and 53 nM (5-OCF3 analogue
2e and 6-OCF3 analogue 2f). On the basis of the observed
potency and reasonable ADME profile 2e was selected for
efficacy studies.10 However, although 2e was curative when
dosed orally in the acute P. berghei (ANKA strain) efficacy model,10
it exhibited significant ADME liabilities. Specifically, there was
potential for drugÀdrug interactions with an observed IC50 of
0.1 μM for the CYP2D6 isozyme and a potential cardiovascular
safety risk based on a hERG IC50 of <2.8 μM.
2a was approximately 3À6-fold more potent than the 5-Me and
6-Me analogues 2bÀc (Table 2) in the cellular 3D7 and Dd2
assays. We were encouraged by the more hydrophilic 4-OMe
analogue 2i (cLogP of 3.6), which was 9-fold less potent than 2e
but did not inhibit hERG or CYP. In an attempt to improve the
potency, the lipohilicity was slightly increased by preparing the
4-OCHF2 analogue 2j (cLogP of 4.1). Gratifingly, the potency
was approximately 4-fold higher than 2i, PfDHODH IC50 of 44
vs 162 nM with a cellular activity in the range of 19À26 nM.
More importantly, the P450 inhibition was >10 μM for all five
primary drug-metabolizing isozymes, and the hERG IC50 was
28.8 μM. As a consequence, 2j was chosen for further in vivo
evaluation.10
Although 2j had an acceptable profile, there was room for
further potency enhancement. As a result, a series of substituents
at the 4-position were prepared (Table 2), and it was found that
electron-withdrawing groups such as F, Cl, Br, and CN (2lÀq)
afforded an approximate 5-fold gain in cellular potency as com-
pared to 2j. For example, the IC50 of the 4-F compound 2l was
8 and 6 nM in 3D7 and Dd2, respectively. However, when con-
sidering physicochemical properties, potential drugÀdrug
interactions mediated via CYPP450 inhibition and potential
cardiovascular safety the 4-CN analogue 2q had the best
overall profile.
We determined that the ADME properties could be improved
by reducing the lipohilicity as measured by cLogP. Our first
strategy was to focus on 4-substituents since the 4-Me analogue
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Table 3. Pharmacokinetics, in Vitro ADMEa Properties, and in Vivo Efficacy of 2q
IV dose (1 mg/kg)
PO dose (3 mg/kg)
AUC0-inf (ng*h/mL) Cmax (ng/mL)
species
AUC0-inf (ng*h/mL)
CL (mL/min/kg)
Vdss (mL/kg)
t1/2 (h)
F (%)
rat
703
24.0
6.7
995
279
0.85
0.52
1038
359
618
49
19
dog
1500
1110
microsomes predicted
CLb (mL/min/kg)
hepatocytes predicted
CLc (mL/min/kg)
protein binding
(%)
CYP450d IC50
PAMPA permeability Â
species
(μM)
10À6 cm/s
mouse
rat
5.8
5.3
14
81.8
78.0
68.8
88.8
na
49
16
na
dog
3.8
12
na
human
<0.7
<0.6
all > 10
in vivo efficacy model
ED50 (mg/kg/day)
ED90 (mg/kg/day)
ED99 (mg/kg/day)
P. berghei ANKA
P. falciparum 3D70087/N9
13
13
28
27
62
60
a Assay conditions reported in ref 10. b Using well-stirred model with correction for microsomal and protein binding. c Using well-stirred model with
correction for protein binding. d CYP1A2, CYP2C9, CYP2C19, CYP3A4, and CYP2D6 were evaluated.
The second strategy that was adopted to optimize the ADME/
PK properties of 2j was to prepare the des 2-methyl benzimidazole
analogues (2t, 2vÀw, 2p) since the cLogP was reduced by
approximately half a log unit (Table 2). These compounds were
synthesized by the Cu(I)-catalyzed coupling of 3b with the cor-
responding substituted benzimidazoles in the presence of cata-
lytic amounts of Cu2O and quinolin-8-ol in DMSO (Scheme 1).
On the basis of the SAR from Table 1, we anticipated that the in
vitro metabolic stability would be poorer for the des-methyl com-
pounds, and indeed, this was the case. We were surprised, however,
to observe that the selectivity for HsDHODH with the des-
methyl compounds increased in the range of 3100À1700 vs
>30000 nM for the 2-methyl analogues. Because of the poorer
selectivity and low in vitro metabolic stability, these compounds
were not further pursued.
The 5- and 6-substituted analogues were prepared by the
Pd(0)-catalyzed coupling of the appropriately substituted 1-bro-
mo-2-nitrobenzenes (4bÀc, 4fÀk) (Scheme 2) with 3d in the
presence of Xantphos to afford intermediates 5 in good yield
similar to a procedure reported by Hornberger et al.12 The inter-
mediates 5 were readily transformed to the target compounds
(2bÀc, 2eÀk, 2x) using the following four step sequence.
The nitro group of 5 was reduced to the amine by hydrogenation
in the presence of Pd(OH)2/C followed by cyclization with
(EtO)3CMe to give the substituted benzimidazoles. To complete
the synthesis, the ester was hydrolyzed to the acid using LiOH,
which was then converted to the cyclopropyl amide via the acid
chloride. It should be pointed out that during the cyclization
reaction substituting (MeO)3CH for (EtO)3CMe afforded the
des methyl compound 2x.
5-(4-cyano-2-methyl-1H-benzo[d]imidazol-1-yl)-N-cyclopro-
pylthiophene-2-carboxamide 2q (Scheme 2).
We examined the species selectivity for the series and found
that the compounds exhibited equipotent activity against DHODH
from P. falciparum, P. vivax, and P.berghei, an important attribute
for developing a candidate with pan-parasite activity. Addition-
ally, 2aÀs and 2u lack activity against the human enzyme (HsD-
HODH IC50 > 30 μM). The series also showed an excellent
correlation between enzymatic activity (DHODH from P. falci-
parum, P. berghei, and P. vivax) and cellular activity (3D7 and
Dd2),10 suggesting that the species specificity exhibited for
DHODH inhibition correlates with a specific effect on the parasites
as compared with representative mammalian cells.
Additional in vivo and in vitro data for compound 2q including
rodent 7 day repeat dose toxicology studies have been completed
(Table 3). The pharmacokinetics of 2q in rat and dog were
determined, and it was found to have moderate oral bioavailability
(F %), 49 and 19%, respectively. The in vitro ADME profile was
encouraging, particularly the predicted low hepatic metabolic
clearance determined in human microsomes and heptocytes,
<0.7 and <0.6 mL/min/kg, respectively. In a repeat dose toxicol-
ogy study in rat at 0, 50, 150, 450, and 600 mg/kg PO QD for
7 days followed by a 7 day washout period, the NOAEL was >600
mg/kg (Cmax, 29 μg/mL; AUC, 328 μg*h/mL), and the predicted
human therapeutic margin was >5.5. No off-target activities in a
54-receptor pharmacologypanel (Cerep ExpresSProfile) at10 μM
were observed corroborating on target activity against pfDHODH.
In addition, an Ames test using Salmonella typhimurium TA98,
100, and 1535, with and without S9 induction, revealed no
evidence of activity at concentrations up to 100 μM.
Compounds with electron-withdrawing groups (F, Cl, CN) at
the 4-position (2lÀn, 2q) were synthesized by the direct
coupling of 3-fluoro-2-nitro(substituted)benzene (4l-o, 4q) with
3d in the presence of KOH and catalytic amounts of BnEt3NCl in
DMF to afford the intermediates 5a. For the synthesis of the
nitrile 2q, the nitro group of 5a was reduced with SnCl2 in HCl
followed by cyclization to the benzimidazole and hydrolysis of
the ester as described above. However, to avoid side reactions
with the nitrile, the amide was formed via peptide coupling
methodology using HCTU and cyclopropylamine to afford
Lastly, the efficacy of 2q was evaluated by PO dosing in two
additional mouse models of malaria, the P. berghei ANKA and
P. falciparum 3D70087/N9 models, and the ED50, ED90, and ED99
values ranged from 13 to 62 mg/kg/day, demonstrating the pre-
dicted potency. On the basis of these data and previously reported
data10 [11% free fraction of drug in human plasma, no P450
inhibition (IC50 > 10 μM), hERG IC50 of 53 μM], 2q was
considered for development.
In conclusion, we successfully optimized an early lead to
generate a novel low molecular weight compound that is orally
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LETTER
bioavailable in three species and efficacious in three mouse models
of malaria. On the basis of these results and the favorable druglike
properties, 2q has been chosen as a potential drug development
candidate.
of plasmodium falciparum dihydroorotate dehydrogenase. J. Biol. Chem.
2008, 283, 35078–35085.
(10) Booker, M. L.; Bastos, C. M.; Kramer, M. L.; Barker, R. H., Jr.;
Skerlj, R.; Sidhu, A. B.; Deng, X.; Celatka, C.; Cortese, J. F.; Guerrero
Bravo, J. E.; Crespo Llado, K. N.; Serrano, A. E.; Barturen, I. A.; Jimenez
Diaz, M. B.; Viera, S.; Garuti, H.; Wittlin, S.; Papastogiannidis, P.; Lin, J.;
Janse, C. J.; Khan, S. M.; Duraisingh, M.; Coleman, B.; Goldsmith, E. J.;
Phillips, M. A.; Munoz, B.; Wirth, D. F.; Klinger., J. D.; Weigand, R.;
Sybertz, E. Novel inhibitors of plasmodium falciparum dihydroorotate
dehydrogenase with antimalaria activity in the mouse model. J. Biol.
Chem. 2010, 285, 33054–33064.
’ ASSOCIATED CONTENT
S
Supporting Information. Experimental procedures and
b
characterization data for the synthesis for compounds 1bÀf,i,k,
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’ AUTHOR INFORMATION
Corresponding Author
*E-mail: renato.skerlj@genzyme.com.
Funding Sources
This work was supported by SPARC funds from the Broad Institute,
with funds from Medicines for Malaria Venture, and with support
from the Humanitarian Assistance for Neglected Diseases In-
itiative at Genzyme Corporation. Genzyme is committed to as-
sisting in discovery of drugs for neglected diseases in collabora-
tion with other partners and seeks no profit from drugs used for
these applications.
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