Exploration of phenylpropanoic acids as agonists of the free fatty acid receptor 4 (FFA4): Identification of an orally efficacious FFA4 agonist

Article abstract of DOI:10.1016/j.bmcl.2017.01.034

The long chain free fatty acid receptor 4 (FFA4/GPR120) has recently been recognized as lipid sensor playing important roles in nutrient sensing and inflammation and thus holds potential as a therapeutic target for type 2 diabetes and metabolic syndrome. To explore the effects of stimulating this receptor in animal models of metabolic disease, we initiated work to identify agonists with appropriate pharmacokinetic properties to support progression into in vivo studies. Extensive SAR studies of a series of phenylpropanoic acids led to the identification of compound 29, a FFA4 agonist which lowers plasma glucose in two preclinical models of type 2 diabetes.

Full text of DOI:10.1016/j.bmcl.2017.01.034

Bioorganic & Medicinal Chemistry Letters xxx (2017) xxx–xxx
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Exploration of phenylpropanoic acids as agonists of the free fatty acid
receptor 4 (FFA4): Identification of an orally efficacious FFA4 agonist
⇑
Steven M. Sparks , Christopher Aquino, Pierette Banker, Jon L. Collins, David Cowan, Caroline Diaz,
Steven T. Dock, Donald L. Hertzog, Xi Liang, Erin D. Swiger, Josephine Yuen, Grace Chen,
Channa Jayawickreme, David Moncol, Christopher Nystrom, Vincent Rash, Thomas Rimele, Shane Roller,
Sean Ross
GlaxoSmithKline, Enteroendocrine Discovery Performance Unit and Platform Technology and Science, 5 Moore Drive, Research Triangle Park, NC 27709, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
The long chain free fatty acid receptor 4 (FFA4/GPR120) has recently been recognized as lipid sensor play-
ing important roles in nutrient sensing and inflammation and thus holds potential as a therapeutic target
for type 2 diabetes and metabolic syndrome. To explore the effects of stimulating this receptor in animal
models of metabolic disease, we initiated work to identify agonists with appropriate pharmacokinetic
properties to support progression into in vivo studies. Extensive SAR studies of a series of phenyl-
propanoic acids led to the identification of compound 29, a FFA4 agonist which lowers plasma glucose
in two preclinical models of type 2 diabetes.
Received 15 December 2016
Revised 10 January 2017
Accepted 11 January 2017
Available online xxxx
Keywords:
Free fatty acid receptor 4
GPR120
Ó 2017 Elsevier Ltd. All rights reserved.
Free fatty acid receptor 1
Phenylpropanoic acid
Type 2 diabetes
Free fatty acids play important roles in biological processes con-
tributing to both health and disease. As essential nutritional com-
ponents, free fatty acids are utilized as building blocks for energy
storage and cell membrane integrity and as substrates for critical
cellular pathways (i.e. Randle cycle1). In addition to these roles,
free fatty acids have been recognized as important signaling mole-
cules involved in a variety of physiological processes including
inflammation and insulin resistance and hence contribute to the
pathologies of type 2 diabetes and obesity.
Recently, numerous G-protein coupled receptors (GPCRs) have
been identified that are activated by free fatty acids.2–6 The GPCRs
can be grouped according to the carbon chain length (short chain:
<6 carbons; medium chain: 6–12 carbons; long chain: >12 carbons)
and level of unsaturation of the fatty acids which activate the
receptors, with free fatty acid receptor 2 (FFA2/GPR43) and free
fatty acid receptor 3 (FFA3/GPR41) activated by short chain fatty
acids, G-protein coupled receptor 84 (GPR84) activated by medium
chain fatty acids, free fatty acid receptor 1 (FFA1/GPR40) activated
by saturated and unsaturated long-chain fatty acids, and free fatty
acid receptor 4 (FFA4/GPR120) activated by unsaturated long-
chain fatty acids including omega-3 fatty acids (
-3 FAs).7,8
x
Our interest in understanding the physiological processes gov-
erned by the long-chain fatty acid receptors led us to further con-
sider FFA1 and FFA4 as candidates for small molecule drug
discovery efforts. Previous reports have highlighted our group’s
efforts leading to the identification of the FFA1 biased agonist
GW9508 (ꢀ100-fold selective for FFA1 over FFA4).9,10 These stud-
ies provided the first evidence that small molecule mediated
FFA1 agonism could be utilized for the pharmacological regulation
of insulin secretion.11 FFA1 is expressed highest in the pancreas,
with insulin secreting b-cells abundantly expressing the receptor,
and has also been shown to also be present in intestine and
brain.12,13 FFA1 amplified glucose-stimulated insulin secretion
has been extensively studied and provides the basis for the current
interest in FFA1 selective small molecule agonists for the treatment
of type 2 diabetes.14–18
FFA4 has been less extensively studied but numerous recent
reports highlight the receptor in several pathologies associated
with type 2 diabetes and the components of metabolic syn-
drome.8,19–21 FFA4 is abundantly expressed in several tissues
including the intestine,22 adipose,23 and lung24 and is present in
a variety of cell types including proinflammatory macrophages,8
intestinal L- and K-cells,22,25 the mouse enteroendocrine STC-1 cell
⇑
Corresponding author at present address: Viamet Pharmaceuticals, 4505
Emperor Blvd., Suite 300, Durham, NC 27703, United States.
E-mail address: ssparks@viamet.com (S.M. Sparks).
http://dx.doi.org/10.1016/j.bmcl.2017.01.034
0960-894X/Ó 2017 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Sparks S.M., et al. Bioorg. Med. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.bmcl.2017.01.034

2
S.M. Sparks et al. / Bioorganic & Medicinal Chemistry Letters xxx (2017) xxx–xxx
line,26 and in the taste buds of the tongue.27 This pattern of expres-
sion is consistent with the nutrient sensing and anti-inflammatory
roles that have been reported for FFA4.21,28–30 Indeed, seminal
studies aimed at identifying the receptors involved in nutrient
stimulated glucagon-like peptide-1 (GLP-1) secretion have identi-
fied FFA4 as a candidate GPCR involved in long-chain fatty acid
stimulated GLP-1 secretion.22 In addition the anti-inflammatory
and insulin sensitizing effects of the
x-3 fatty acids DHA and EPA
have been reported to occur through FFA4.8,30–32 Further under-
standing of the therapeutic potential of FFA4 activation would be
greatly aided by the identification of small molecule agonists with
good pharmacokinetic properties.33–40 With this goal in mind,
efforts directed toward the identification of small molecule FFA4
agonists culminating in identification of phenylpropanoic acid ago-
nists with pharmacokinetic properties appropriate for in vivo stud-
ies are described herein.
Scheme 1. General syntheses of the phenylpropanoic acids. Reagents and condi-
tions: (a) K2CO3, DMF (X = Cl or Br) or DIAD, PPh3 (X = OH); (b) NaOH or LiOH, THF/
MeOH/H2O.
Compound 1 was identified as starting point for optimization
following a cross-screening effort of our FFA1 program compounds
(Fig. 1). The potency and efficacy of compound 1 was determined
using a ten-point dose response curve in mammalian U2OS cells
transiently expressing either human FFA1 or FFA4 using a FLIPR
readout. The data revealed that compound 1 was 17-fold selective
for FFA1 over FFA4. Thus, a primary goal of this exercise was to
explore the SAR against both receptors while identifying com-
pounds with selectivity for the FFA4 receptor.
In addition, several other considerations were made for the
optimization exercise. While the structural features of the endoge-
nous ligands for long-chain fatty acid receptors suggest obtaining
orthosteric agonists with drug-like properties may be challenging,
the optimization efforts were committed to maintaining molecular
weight in the range of compound 1 (MW < 400) while hoping to
realize high plasma drug concentrations, as plasma protein binding
was expected to limit the free fraction of the drug. With these goals
in mind, our efforts directed toward the identification of improved
small molecule FFA4 agonists commenced.
The general synthesis of the phenylpropanoic acid agonists is
shown in Scheme 1. Alkylation of substituted 4-hydroxyphenyl-
propanoic esters with substituted benzyl halides or benzyl alcohols
followed by ester hydrolysis directly yielded the desired phenyl-
propanic acids. The ease of synthesis of the desired compounds
coupled with the commercial availability of the starting materials
allowed for rapid SAR generation.
Phenylpropanoic acid headgroups were prepared as shown in
Scheme 2. In general, ketone or benzaldehyde derivatives (I) were
olefinated and reduced to provide the corresponding propanoates
(III), which in some cases required demethylation (BBr3) to provide
the desired phenols. Hydroxyl derivative 4 was obtained via the
aldol reaction of the corresponding benzaldehyde derivative (I)
with bis-lithiated species of acetic acid. The phenylpropanoic acid
derivative for alcohol 13 was obtained from the corresponding
Scheme 2. General syntheses of the phenylpropanoic phenols. Reagents and
conditions: (a) DIBAL-H, toluene; (b) NaH or t-BuOK, (EtO)2POCH2CO2R, DMF; (c)
n-BuLi, AcOH, THF; (d) 10% Pd/C, H2, THF/MeOH or NiCl2, NaBH4, THF; (e) BBr3, DCM
(f) TiCl4, MeOCHCl2, DCM; (g) 2-methyl-2-propen-1-ol, DIAD, PPh3, toluene, 250 °C.
aldehyde (IV) which in turn was prepared by a titanium-mediated
formylation/deprotection sequence from III. Isobutyl derivative 14
was prepared by the Mitsunobu-initiated Claisen-rearrangement
of the corresponding phenol (III, R0 = H) with 2-methyl-2-propenol
followed by alkene reduction to afford intermediate V.
Benzyl alcohols and their activated derivatives were prepared
as outlined in Scheme 3. Benzoic acids with the desired 2,5-disub-
stitution pattern were reduced directly to the desired benzyl alco-
hol derivatives (VI). Variation of ether group at the 2-position
holding the 5-methyl substituent constant (VII) was accomplished
starting from 5-methyl salicylic acid by simple alkylation followed
by reduction. Formylation of 4-trifluoromethyl phenol followed by
reduction and conversion to the mesylate derivative X allowed for
incorporation of a trifluoromethyl group at the 5-position of the
benzyl alcohol derivatives. 5-Methyl-3-alkoxy-disubstituted ben-
zyl alcohols were prepared starting from 3-methoxy-5-bromoben-
zene utilizing a sequence consisting of deprotection followed by
alkylation to furnish bromide XI, which underwent subsequent
metal-halogen exchange and trapping to provide the intermediate
aldehyde which was reduced to afford the desired benzyl alcohol
derivatives (XII).
Fig. 1. In vitro profile of FFA1 agonist 1.
Please cite this article in press as: Sparks S.M., et al. Bioorg. Med. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.bmcl.2017.01.034

S.M. Sparks et al. / Bioorganic & Medicinal Chemistry Letters xxx (2017) xxx–xxx
3
Select compounds were derivatized following construction of
the benzyl ether bond (Scheme 4), for instance, compounds con-
taining 5-methyl-3-alkoxy substitution on the benzyl tail were
prepared starting from 3,5-dimethylbromobenzene. Radical halo-
genation followed by benzyl ether formation provided the arylbro-
mide intermediate XIII which underwent palladium catalyzed
etherification41 followed by saponification to provide the desired
diphenylether 31.
Our initial studies explored substitution about the phenyl-
propanoic acid headgroup while holding a 2-thiotrifluoromethyl-
benzyl tail constant (Table 1). Parent compound 2 provided a
nearly balanced FFA1/FFA4 (2-fold selective for FFA4) starting
point and it was hoped that further improvements in potency for
FFA4 could be realized utilizing the benzyl tail of compound 2.
Addition of polarity (3 & 4) along the propanoic acid chain or sim-
ple substitution (5) eroded activity at both receptors. Incorporation
of a methyl substituent at R2 (6) or dimethyl substitution at R3 and
R5 (8) provided no improvement in potency, while methyl substi-
tution at R3 (7) increased activity at FFA4 while diminishing FFA1
activity. Dimethyl substitution (9) provided a selective FFA4 ago-
nist while growing the substitution in the form of a naphthalene
ring (10) led to diminished activity at FFA4. Small nonpolar sub-
stituents at R3, such as the chloro group of 11, provided a further
improvement in FFA4 potency and afforded excellent selectivity
over FFA1, which stands in contrast to the incorporation of more
polar (12 & 13) or larger (14) R3 substituents which led to a reduc-
tion in activity at both receptors.
Scheme 3. General synthetic routes to benzyl alcohol derivatives. Reagents and
conditions: (a) LiAlH4 or BH3dTHF, THF; (b) RI, K2CO3, DMF; (c) 3,4-dihydro-2H-
pyran, PPTS, DCM; (d) n-BuLi; DMF; (e) NaBH4, MeOH; (f) MsCl, Et3N, DCM; (g) BBr3,
DCM.
With the identification of small nonpolar substituents at R3 of
the phenylpropanoic acid ring providing improved activity at
FFA4, exploration of the benzyl SAR was undertaken (Table 2).
Small substituents were well tolerated at both the ortho and meta
positions (15–23) with the 2-bromo- (19), 2-isopropoxy- (18), and
3-methyl-substituents (23) providing potent and selective FFA4
agonists. In select cases incorporation of ortho-meta-disubstitution
(2,5-orientation) and meta-meta-disubstitution (3,5-orientation)
afforded equipotent agonists with the mono-substituted compara-
tors (24 vs. 23; 27 vs. 18 & 23) while for the majority of exemplars
improved potency was realized (25 vs. 19; 26 vs. 23; 28 vs. 23; 29
vs. 21) at FFA4. Benzyl disubstitution provided weak activity at
FFA1. Unmasking polar functionality (30 vs. 29) provided a dra-
matic decrease in activity at FFA4, consistent with the lipophilic
nature of the binding pocket and structures of the natural ligands.
Scheme 4. Synthesis of compound 34. Reagents and conditions: (a) NBS, CCl4 (b)
Ethyl 3-(4-hydroxy-3-methylphenyl)propanoate, K2CO3, DMF (c) Phenol, Pd(OAc)2,
di-t-BuXPhos, K3PO4, toluene (d) LiOH, 1,4-dioxane/H2O.
Table 1
In vitro FFA4 agonism: Phenylpropanoic acid SAR.
a
Cmpd
R2, R3, R5
X
hFFA4 EC50 (% Max Resp.)
hFFA1 EC50 (% Max Resp.)
2
3
4
5
6
7
8
9
10
11
12
13
14
H, H, H
H, H, H
H, H, H
H, H, H
Me, H, H
H, Me, H
H, Me, Me
Me, Me, H
-(CH)4-, H
H, Cl, H
H, OMe, H
H, CH2OH, H
H, CH2CH(CH3)2, H
CH2
O
681 (105)
9977 (85)
>30,000
11,380 (97)
722 (90)
201 (108)
660 (102)
304 (77)
2292 (105)
108 (80)
1423 (77)
>30,000
N.T.
13,142 (109)
1544 (108)
8514 (81)
21,777 (115)
>30,000
>30,000
>10,000
>30,000
>30,000
CHOH
CHCH3
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
CH2
1992 (110)
5911 (53)
9660 (161)
>30,000
a
38
Values are means of three experiments, see the supporting information for standard deviations (N.T. = not tested). EC50 reported in nM. See Ref.
for assay details.
Please cite this article in press as: Sparks S.M., et al. Bioorg. Med. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.bmcl.2017.01.034

4
S.M. Sparks et al. / Bioorganic & Medicinal Chemistry Letters xxx (2017) xxx–xxx
Table 2
In vitro FFA4 agonism: benzyl substitution.
.
a
a
Cmpd
R
hFFA4 EC50 (% Max
Resp)
hFFA1 EC50 (% Max
Resp)
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
H
2-Cl
2-CF3
2-OiPr
2-Br
750 (83)
972 (130)
531 (103)
271 (118)
236 (116)
362 (104)
898 (117)
556 (95)
275 (100)
188 (115)
53 (118)
60 (66)
>30,000
11,588 (80)
8600 (95)
>30,000
>30,000
10,268 (60)
>30,000
3837 (90)
>30,000
18,051 (243)
3-Cl
3-CF3
3-OPh
3-Me
2-Cl-5-Me
2-Br-5-Me
3,5-diMe
2-OiPr-5-Me 172 (106)
3-OiPr-5-Me 60 (112)
2-MeO-5-
CF3
>30,000
Fig. 2. In vitro profile of FFA1 agonist 29.
3782 (97)
19,588 (154)
>30,000
299 (124)
11,803 (105)
30
31
2-OH-5-CF3
3-Me-5-OPh 40 (97)
10,000 (78)
N.T.
1631 (85)
a
Values are means of three experiments, see the supporting information for
38
standard deviations (N.T. = not tested). EC50 reported in nM. See Ref.
details.
for assay
Interestingly, combination of the biphenyl ether moiety of 1 with
the meta-methyl (22) provided the most potent FFA4 agonist of
the series (31).
With
a series of FFA4 agonists with varying degrees of
selectivity over FFA1 in hand, examination of the pharmacokinetic
(PK) properties of select compounds in C57Bl6 mice was initiated
(Table 3). In general, the compounds were characterized with
low to moderate IV clearance, low volumes of distribution
(Vss < 2 L/kg), and rapid oral absorption (Tmax values of
0.25–0.5 h). Compound 29 showed good oral exposure and high
oral bioavailability with moderate half-life (t½ = 1.7 h). Examina-
tion of the protein binding of the compounds revealed all to be
>99% bound in human plasma with 99.9% protein binding
measured for compound 29. Despite high protein binding,
compound 29 was chosen as a tool molecule for in vivo studies
based upon its superior oral exposure (Cmax = 6779 ng/mL),
potency at FFA4 (EC50 = 299 nM), and selectivity over human
Fig. 3. Effect of FFA4 agonist 29 on plasma glucose in 8-week old male ZDF rats
(n = 8) treated orally twice a day at the indicated doses for 14 days. *p < 0.05 vs
vehicle.
receptors (40-fold). With respect to activity on the remaining
members of the free fatty acid family, compound 29 showed weak
partial agonism of the FFA2 receptor and profiled as inactive
against FFA3 in FLIPR based assays. The remainder of the panel
included a mixture of GPCR, ion channel, and enzyme assays with
compound 29 showing robust selectivity against the panel.
Investigation of the anti-diabetic properties of compound 29
was undertaken in Zucker Diabetic Fatty (ZDF) rats, an established
preclinical model of type 2 diabetes. Compound 29 was adminis-
tered to 8-week old male ZDF rats at doses of 10 and 100 mg/kg
twice daily for 14 days with plasma glucose concentrations deter-
mined at baseline, 7 and 14 days.
FFA1 (EC50 = 11.8 lM).
Prior to in vivo studies, the in vitro selectivity of compound 29
was evaluated in a panel of targets in both full curve binding and
functional assays including the rodent ortholog assays for FFA1
and FFA4 and additional members of the free fatty acid receptor
family (Fig. 2). Increased selectivity (>85-fold) for both rat and
mouse FFA4 over FFA1 was realized relative to the human
Table 3
DMPK profiles of selected FFA4 agonists in C57BL/6 J mice.a
Cmpd
IV Cl (mL/min/kg)
IV AUC (hr⁄ng/mL)
PO Cmax (ng/mL)
PO AUC (hr⁄ng/mL)
% F
23
24
26
28
29⁄
12
18
35
43
20
4105
2859
1416
1171
3618
3083
3028
2627
687
5353
4403
2596
767
39
46
55
20
6779
9438
110
C57BL/6 J Mice (n = 2), Oral dose = 10 mg/kg, IV dose = 3 or 4.2⁄ mg/kg. PO formulation: 0.5% HMPC: 0.1% Tween suspension; IV formulation: 2% DMSO, 5% solutol.
a
Please cite this article in press as: Sparks S.M., et al. Bioorg. Med. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.bmcl.2017.01.034

S.M. Sparks et al. / Bioorganic & Medicinal Chemistry Letters xxx (2017) xxx–xxx
5
6. Yonezawa T, Kurata R, Yoshida K, Murayama MA, Cui X, Hasegawa A. Free fatty
acids-sensing G protein-coupled receptors in drug targeting and therapeutics.
Curr Med Chem. 2013;20:3855–3871.
7. Burns RN, Moniri NH. Agonism with the omega-3 fatty acids Î -linolenic acid
and docosahexaenoic acid mediates phosphorylation of both the short and long
isoforms of the human GPR120 receptor. Biochem Biophys Res Commun.
2010;396:1030–1035.
8. (a) Oh DY, Talukdar S, Bae EJ, et al. GPR120 is an omega-3 fatty acid receptor
mediating potent anti-inflammatory and insulin-sensitizing effects. Cell.
2010;142:687–698;
(b) Oh DY, Walenta E, Akiyama TE, et al. A Gpr120-selective agonist improves
insulin resistance and chronic inflammation in obese mice. Nat Med.
2014;20:942–947.
9. Garrido DM, Corbett DF, Dwornik KA, et al. Synthesis and activity of small
molecule GPR40 agonists. Bioorg Med Chem Lett. 2006;16:1840–1845.
10. McKeown SC, Corbett DF, Goetz AS, et al. Solid phase synthesis and SAR of small
molecule agonists for the GPR40 receptor. Bioorg Med Chem Lett.
2007;17:1584–1589.
11. Briscoe CP, Peat AJ, McKeown SC, et al. Pharmacological regulation of insulin
secretion in MIN6 cells through the fatty acid receptor GPR40: identification of
agonist and antagonist small molecules. Br J Pharmacol. 2006;148:619–628.
12. Briscoe CP, Tadayyon M, Andrews JL, et al. The orphan G protein-coupled
receptor GPR40 is activated by medium and long chain fatty acids. J Biol Chem.
2003;278:11303–11311.
13. Itoh Y, Kawamata Y, Harada M, et al. Free fatty acids regulate insulin secretion
from pancreatic Î2 cells through GPR40. Nature. 2003;422:173–176.
14. Burant CF. Activation of GPR40 as a therapeutic target for the treatment of type
2 diabetes. Diabetes Care. 2013;36:S175–S179.
15. Choi YJ, Shin D, Lee JY. G-protein coupled receptor 40 agonists as novel
therapeutics for type 2 diabetes. Arch Pharmacal Res. 2013. Ahead.
16. Feng XT, Leng J, Xie Z, Li SL, Zhao W, Tang QL. GPR40: a therapeutic target for
mediating insulin secretion (review). Int J Mol Med. 2012;30:1261–1266.
17. Kaku K. Fasiglifam as a new potential treatment option for patients with type 2
diabetes. Expert Opin Pharmacother. 2013;14:2591–2600.
18. Poitout V, Lin DCH. Modulating GPR40: therapeutic promise and potential in
diabetes. Drug Discovery Today. 2013;18:1301–1308.
19. Ichimura A, Hirasawa A, Poulain-Godefroy O, et al. Dysfunction of lipid
sensor GPR120 leads to obesity in both mouse and human. Nature. 2012;483:
350–354.
20. Mo XL, Wei HK, Peng J, Tao YX. Free fatty acid receptor GPR120 and
pathogenesis of obesity and type 2 diabetes mellitus. Prog Mol Biol Transl Sci.
2013;114:251–276.
21. Talukdar S, Olefsky JM, Osborn O. Targeting GPR120 and other fatty acid-
sensing GPCRs ameliorates insulin resistance and inflammatory diseases.
Trends Pharmacol Sci. 2011;32:543–550.
22. Hirasawa A, Tsumaya K, Awaji T, et al. Free fatty acids regulate gut incretin
glucagon-like peptide-1 secretion through GPR120. Nat Med. 2005;11:90–94.
23. Gotoh C, Hong YH, Iga T, et al. The regulation of adipogenesis through GPR120.
Biochem Biophys Res Commun. 2007;354:591–597.
24. Miyauchi S, Hirasawa A, Iga T, et al. Distribution and regulation of protein
expression of the free fatty acid receptor GPR120. Naunyn-Schmiedeberg’s Arch
Pharmacol. 2009;379:427–434.
25. Parker HE, Habib AM, Rogers GJ, Gribble FM, Reimann F. Nutrient-dependent
secretion of glucose-dependent insulinotropic polypeptide from primary
murine K cells. Diabetologia. 2009;52:289–298.
26. Tanaka T, Katsuma S, Adachi T, Koshimizu TA, Hirasawa A, Tsujimoto G. Free
fatty acids induce cholecystokinin secretion through GPR120. Naunyn-
Schmiedeberg’s Arch Pharmacol. 2008;377:523–527.
27. Martin C, Passilly-Degrace P, Chevrot M, et al. Lipid-mediated release of GLP-1
by mouse taste buds from circumvallate papillae: putative involvement of
GPR120 and impact on taste sensitivity. J Lipid Res. 2012;53:2256–2265.
28. Ichimura A, Hirasawa A, Hara T, Tsujimoto G. Free fatty acid receptors act as
nutrient sensors to regulate energy homeostasis. Prostaglandins Other Lipid
Mediators. 2009;89:82–88.
Fig. 4. Effect of compound 29 on blood glucose in db/db mice (n = 10) dosed at
100 mg/kg BID as compared to vehicle. *p < 0.05 vs vehicle.
All groups of ZDF rats had comparable levels of plasma glucose,
insulin, and HbA1c prior to treatment. As illustrated in Fig. 3, the
vehicle-treated animals showed a progressive hyperglycemia with
plasma glucose rising from baseline values of 188 to 245 mg/dL. In
contrast, plasma glucose for compound 29 treated animals was
reduced to 151 and 139 mg/dL at the 10 and 100 mg/kg doses,
respectively, from a starting average of 192 mg/dL.
With positive effects on plasma glucose measured in the ZDF
rat, compound 29 was progressed into a second rodent model of
type 2 diabetes, the db/db mouse. In this model fed db/db mice
were orally administered either vehicle or compound 29
(100 mg/kg) twice a day and blood glucose was measured before
and after 1 and 2 weeks of treatment. In addition, HbA1c levels
were measured before and after 2 weeks of treatment. As shown
in Fig. 4, compound 29 gave a robust response, normalizing blood
glucose after 1 week of treatment. Glucose lowering was main-
tained through the end of the study with levels for the compound
29 treated animals finishing at 106 mg/dL versus 276 mg/dL for
vehicle controls. Compound 29 also robustly lowered HbA1c levels
by 1.6% to a final value of 5.8% with the vehicle control group fin-
ishing the study at 7.8%.
In summary, the SAR of a series of phenylpropanoic acid-free
fatty acid receptor agonists is described which resulted in the iden-
tification of potent FFA4 agonists. The superior pharmacokinetic
properties of compound 29 led to its selection as an in vivo tool
compound which afforded robust efficacy in two rodent models
of type 2 diabetes. In vivo results with compound 29 detail the
potential for FFA4 agonists as treatments for type 2 diabetes and
additional factors associated with metabolic syndrome.
A. Supplementary material
29. Nguyen CA, Akiba Y, Kaunitz JD. Recent advances in gut nutrient chemosensing.
Curr Med Chem. 2012;19:28–34.
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2017.01.
034.
30. Oh D, Lagakos WS. The role of G-protein-coupled receptors in mediating the
effect of fatty acids on inflammation and insulin sensitivity. Curr Opin Clin Nutr
Metab Care. 2011;14:322–327.
31. Im DS. Omega-3 fatty acids in anti-inflammation (pro-resolution) and GPCRs.
Prog Lipid Res. 2012;51:232–237.
32. Morishita M, Tanaka T, Shida T, Takayama K. Usefulness of colon targeted DHA
and EPA as novel diabetes medications that promote intrinsic GLP-1 secretion. J
Controlled Release. 2008;132:99–104.
References
33. Cornall LM, Mathai ML, Hryciw DH, McAinch AJ. GPR120 agonism as
a
1. Hue L, Taegtmeyer H. The Randle cycle revisited: a new head for an old hat. Am J
Endocrinol MeTable. 2009;297:E578–E591.
countermeasure against metabolic diseases. Drug Discovery Today.
2014;19:670–679.
34. Halder S, Kumar S, Sharma R. The therapeutic potential of GPR120: a patent
review. Expert Opin Ther Pat. 2013;23:1581–1590.
35. Hara T, Hirasawa A, Ichimura A, Kimura I, Tsujimoto G. Free fatty acid receptors
FFAR1 and GPR120 as novel therapeutic targets for metabolic disorders. J Pharm
Sci. 2011;100:3594–3601.
36. Hudson BD, Shimpukade B, Mackenzie AE, et al. The pharmacology of TUG-891,
a potent and selective agonist of the free fatty acid receptor 4 (FFA4/GPR120),
demonstrates both potential opportunity and possible challenges to
therapeutic agonism. Mol Pharmacol. 2013;84:710–725.
2. Layden BT, Angueira AR, Brodsky M, Durai V, Lowe Jr WL. Short chain fatty acids
and their receptors: new metabolic targets. Transl Res. 2013;161:131–140.
3. Stoddart LA, Smith NJ, Milligan G. International union of pharmacology. LXXI.
Free fatty acid receptors FFA1, -2, and -3: pharmacology and pathophysiological
functions. Pharmacol Rev. 2008;60:405–417.
4. Vangaveti V, Shashidhar V, Jarrod G, Baune BT, Kennedy RL. Free fatty acid
receptors: emerging targets for treatment of diabetes and its complications.
Ther Adv Endocrinol MeTable. 2010;1:165–175.
5. Vinolo MAR, Hirabara SM, Curi R. G-protein-coupled receptors as fat sensors.
Curr Opin Clin Nutr Metab Care. 2012;15:112–116.
Please cite this article in press as: Sparks S.M., et al. Bioorg. Med. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.bmcl.2017.01.034

6
S.M. Sparks et al. / Bioorganic & Medicinal Chemistry Letters xxx (2017) xxx–xxx
37. Medina JC, Houze JB. GPR40 (FFAR1) modulators. Annu Rep Med Chem.
2008;43:75–85.
38. Sparks SM, Chen G, Collins JL, et al. Identification of diarylsulfonamides as
agonists of the free fatty acid receptor 4 (FFA4/GPR120). Bioorg Med Chem Lett.
2014;24:3100–3103.
40. Lombardo M, Bender K, London C, et al. Discovery of benzofuran propanoic acid
GPR120 agonists: from uHTS hit to mechanism-based pharmacodynamic
effects. Bioorg Med Chem Lett. 2016;26:5724–5728.
41. Burgos CH, Barder TE, Huang X, Buchwald SL. Significantly improved method
for the Pd-catalyzed coupling of phenols with aryl halides: understanding
ligand effects. Angew Chem Int Ed. 2006;45:4321–4326.
39. Azevedo CM, Watterson KR, Wargent ET, et al. Non-acidic free fatty acid
receptor 4 agonists with antidiabetic activity. J Med Chem. 2016;59:8868–8878.
Please cite this article in press as: Sparks S.M., et al. Bioorg. Med. Chem. Lett. (2017), http://dx.doi.org/10.1016/j.bmcl.2017.01.034