Discovery of 12-Thiazole Abietanes as Selective Inhibitors of the Human Metabolic Serine Hydrolase hABHD16A

Article abstract of DOI:10.1021/acsmedchemlett.8b00442

Screening of an in-house library of compounds identified 12-thiazole abietanes as a new class of reversible inhibitors of the human metabolic serine hydrolase. Further optimization of the first hit compound lead to the 2-methylthiazole derivative 18, with an IC₅₀ value of 3.4 ± 0.2 μM and promising selectivity. ABHD16A has been highlighted as a new target for inflammation-mediated pain, although selective inhibitors of hABHD16A (human ABHD16A) have not yet been reported. Our study presents abietane-type diterpenoids as an attractive starting point for the design of selective ABHD16A inhibitors, which will contribute toward understanding the significance of hABHD16A inhibition in vivo.

Full text of DOI:10.1021/acsmedchemlett.8b00442

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Letter
Discovery of 12-thiazole abietanes as selective inhibitors
of the human metabolic serine hydrolase hABHD16A
Tiina J. Ahonen, Juha R. Savinainen, Jari Yli-Kauhaluoma, Eija Kalso, Jarmo T Laitinen, and Vânia M. Moreira
ACS Med. Chem. Lett., Just Accepted Manuscript • DOI: 10.1021/acsmedchemlett.8b00442 • Publication Date (Web): 13 Nov 2018
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ACS Medicinal Chemistry Letters
Discovery of 12-thiazole abietanes as selective inhibitors of the
human metabolic serine hydrolase hABHD16A
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†
‡
†
§,‖
‡
Tiina J. Ahonen, Juha R. Savinainen, Jari Yli-Kauhaluoma, Eija Kalso, Jarmo T. Laitinen, and
†
,,*
Vânia M. Moreira
†Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Finland
‡School of Medicine, Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland
§Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
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‖Department of Anaesthesiology, Intensive Care and Pain Medicine, Helsinki University Hospital and University of Helsinki, Finland
Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, UK
KEYWORDS: hABHD16A inhibitor; metabolic serine hydrolase; lysophosphatidylserine; dehydroabietic acid
ABSTRACT: Screening of an in-house library of compounds identified 12-thiazole abietanes as a new class of reversible inhibitors
of the human metabolic serine hydrolase. Further optimization of the first hit compound lead to the 2-methylthiazole derivative 18,
with an IC50 value of 3.4 ± 0.2 µM and promising selectivity. ABHD16A has been highlighted as a new target for inflammation-
mediated pain, although selective inhibitors of hABHD16A (human ABHD16A) have not yet been reported. Our study presents
abietane-type diterpenoids as an attractive starting point for the design of selective ABHD16A inhibitors, which will contribute
towards understanding the significance of hABHD16A inhibition in vivo.
Inflammation of tissue within the peripheral and central nervous
system, known as neuroinflammation, has been implicated in
the development of chronic pain via sensitization of nociceptive
weights and poor aqueous solubility, which limits their use in
biological assays and further development into drug leads.
Smaller molecular weight diterpenoids of the abietane family
are much more interesting from this perspective especially
because a few, including methyl carnosate and miltirone, cross
1,2
neurons. Therefore, identifying and targeting the processes
and molecules involved in neuroinflammation is regarded as an
effective strategy for innovative chronic pain treatments. In this
regard, the metabolic serine hydrolase ABHD16A, also known
as BAT5, belonging to the ABHD (α,β-hydrolase domain)
enzyme family is a potentially novel key target in inflammation-
9
the blood-brain barrier and bear analgesic properties.
O
O
MeO
MeO
3
,4
mediated pain. This enzyme is mostly expressed in the brain,
muscle, heart and testis, where its activity is closely coupled
with that of ABHD12 to regulate the levels of pro-inflammatory
HN
O
O
O
lysophosphatidylserine (lyso-PS).3,5
O
More specifically,
8
6
ABHD16A converts phosphatidylserine (PS) to lyso-PS, which
is either recycled back to PS or further hydrolyzed by ABHD12
to glycerophosphoserine. Accordingly, deletion of ABHD12
results in high levels of lyso-PS in the brain and microglial
activation whereas pharmacological or genetic perturbation of
ABHD16A decreases the levels of lyso-PS and ameliorates
inflammation. It is therefore desirable to block the activity of
ABHD16A without concomitant inhibition of ABHD12.
O
Palmostatin B6
IC50 = 100 nM
RPa = 1.7
)-Tetrahydrolipstatin6
IC50 = 170 nM
Other activities: ABHD6, ABHD127
(
Other activities: ABHD12, LYPLA1/26
F
NH2
ABHD16A is a membrane-bound enzyme and in the absence of
a crystal structure, the search for inhibitors has been based on
O
11
N
N
O
O
3
,6
OMe
competitive activity-based protein profiling (ABPP).
Palmostatin B, tetrahydrolipstatin (THL), 1,3,4-oxadiazol-
(3H)-ones and KC01 have all been reported to inhibit
O
O
KC013
Compound 446
2
IC50 = 90 ± 20 nM
RPa = 1.3
IC50 = 32 nM
RPa = 5.3
ABHD16A, some with nanomolar potency, however the
3,6,7
selectivity is still poor (Figure 1).
Other activities: ABHD2, ABHD33
Other activities: KIAA13636
Previously, we have shown that pentacyclic triterpenoids
including maslinic acid bear unprecedented selectivity for
inhibition of ABHD12 over other serine hydrolases, as well as
Figure 1. Examples of known ABHD16A inhibitors and their
reported selectivity. RP = Relative potency ratio related to THL
expressed as IC50 (THL) / IC50 (compound), under the same assay
conditions.
a
8
over cannabinoid receptors. A ligand-based pharmacophore
model highlighted the planar hydrophobic hydrocarbon core
among the relevant pharmacophoric features. Compounds in
this class of triterpenoids, however, have high molecular
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Scheme 1. Synthesis of 12-thiazole abietanes 5–8 and 11–14 from dehydroabietic acid 1.
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9
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5
6
R
R
R
O
S
S
12
O
N
N
Br
C
14
b
c
d or e
f
A
B
H
H
H
1
8OR
OMe
O
OMe
H
H
O
OMe
O
O
HO
R = H, Dehydroabietic acid (1)
R = Me, 2
3
A mixture of 4a and 4b:
R = H 4a / R = Br 4b
R = NH2 5 (40%)
R = H 6 (53%)
R = NH2 7 (28%)
R = H 8 (67%)
0
1
2
3
4
5
6
7
8
9
0
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0
a
g, h
O
g
R
S
R
S
N
O
N
Br
c
d or e
H
NH2
H
H
H
NH2
OR
O
NH2
O
O
O
9
(74%)
A mixture of 10a and 10b:
R = H 10a / R = Br 10b
R = NH2 11 (27%)
R = H 12 (55%)
R = H 13 (6%)
R = CH CH OH 14 (42%)
2
2
Reagents and conditions: (a) MeI, K
2
CO
3
, DMF, rt, 2.5 h. (b) MeCOCl, AlCl
3
, CH
2
Cl
2
2
, 0 ºC  r.t., 3.5 h. (c) CuBr , MeOH, 65 ºC, 16 h.
(
d) Thiourea, Et N, dry EtOH, reflux, 1 h 45 min, or 120 ºC with microwaves, 30 min. (e) Thioformamide, dry 1,4-dioxane, 100 ºC with
3
microwaves, 10 min. (f) LiAlH
19 h.
4
2 3
, THF, 0 ºC  r.t. (g) KOH, ethylene glycol, H O, 130 ºC. (h) HOBt, EDC-HCl, aq. NH , DMF, 0 ºC  r.t.,
When we screened an in-house library of 50 abietanes for their
ability to inhibit hydrolase activity in lysates of HEK293 cells
However, it was retained by the alcohol 8, even if less
pronounced when compared to the ester 6 (Table 1).
6
transiently overexpressing human ABHD16A, at 10 µM,
Table 1. Remaining hydrolase activity for hABHD12 and
hABHD16A (% control) at 10 µM concentration.
7
ruling out concomitant inhibition of human ABHD12, the 2-
aminothiazole 5 (Scheme 1) was the only compound showing
moderate inhibition of hABHD16A without interfering with
hABHD12 (Table 1). Its synthesis proceeded from methyl
dehydroabietate 2 which gave 3 by Fridel-Crafts acylation
Compound
hABHD16A
% control)
hABHD12
(% control)
Mean ± SD, n=2-3
(
Mean ± SD, n=2-3
58.2 ± 18.1
50.3 ± 4.6
74.6 ± 7.5
65.9 ± 2.8
80.0 ± 5.6
82.1 ± 4.3
91.5 ± 2.8
62.9 ± 3.4
73.8 ± 4.7
86.6 ± 0.8
99.3 ± 2.4
23.0 ± 16.3
48.7 ± 0.5
42.8 ± 4.1
66.3 ± 5.9
98.4 ± 0.8
80.6 ± 1.8
82.7 ± 4.2
1
0
(
Scheme 1), followed by bromination of the carbon alpha to
5
6
7
8
102.6 ± 2.3
91.5 ± 0.4
87.8 ± 0.8
96.3 ± 1.0
96.9 ± 0.8
98.7 ± 0.2
98.4 ± 0.2
77.8 ± 1.0
89.8 ± 0.1
100.9 ± 4.1
96.6 ± 8.8
100.1 ± 1.1
73.8 ± 3.2
94.3 ± 0.7
98.7 ± 2.2
101.9 ± 0.0
99.6 ± 1.0
92.8 ± 1.2
1
1
2
the carbonyl group with CuBr , in refluxing MeOH. The
reaction resulted in a mixture of mono- and dibromo
compounds 4a and 4b, which was used without further
purification in the reaction with thiourea to give 5, in 40% yield,
over two steps.
1
1
In the light of the well-known canonical esterase mechanism for
1
2

/-hydrolase fold enzymes, we reasoned that the ring A ester
12
in 5 would likely account for the observed activity. In addition,
1
3
aminothiazoles are generally known to be promiscuous assay-
interfering compounds13 so it was important to determine
14
15
whether the 2-amino substituent was relevant for the observed
1
4
activity. The ester was first modified by reduction to alcohol
7 or replaced with the amide 11, as depicted on Scheme 1. A
thiazole derivative 6, devoid of a 2-amino substituent, was
prepared by reacting 4 and thioformamide under microwave
conditions, in 53% yield.
1
1
6
7
18
19
Modification of the ring A ester resulted in modest inhibition of
hABHD16A in 7 and 11, whereas 6 inhibited the enzyme
slightly more efficiently than 5. A new round of modifications
of the ring A ester in 6 gave the amide 12 via a synthetic route
similar to that of 11, and the carboxylic acid 13, from the
alkaline hydrolysis of 6 (Scheme 1). Enzyme inhibition was
almost abrogated with the amide 12 and the carboxylic acid 13.
2
2
2
0
1
2
23
24
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2
2
5
6
81.5 ± 4.9
80.1 ± 1.6
91.1 ± 1.7
91.1 ± 2.9
dimethylaminopropyl)-N′-ethylcarbodiimide
hydrochloride
(EDC-HCl), and further reaction with ammonia, in 77% yield.
As before, inhibition of hABH16A was almost abrogated in the
carboxylic acid and amide derivatives whereas the alcohol 21
was half as potent as the parent ester (Table 1). The synthesis
of 20, where the methyl substituent was replaced by an electron-
withdrawing nitrile group, proceeded from 4 and ethyl
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2
3
4
5
6
7
8
9
Interestingly, 14, which was the main product obtained in the
hydrolysis reaction of 6, showed inhibition of hABHD16A
comparable to that of the alcohol 8, however with weaker
selectivity, as approximately 20% inhibition of ABHD12 was
observed. Overall these results suggested that both the thiazole
ring and the substituent at ring A were relevant for the activity
with the 2-amino substituent in the heterocycle not being an
essential feature, and ring A substitution being flexible between
an ester and an alcohol, the ester performing better in terms of
potency and selectivity.
thiooxamate and continued with the hydrolysis of 19, with NH
in MeOH to give an intermediate amide, which was further
converted to the nitrile 20 using trifluoroacetic acid and
triethylamine in tetrahydrofuran, in 46% yield. Both 19 and
3
15
1
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1
1
1
1
1
1
1
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2
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2
2
2
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2
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5
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5
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0
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0
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9
0
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9
0
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2
3
4
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7
8
9
0
1
2
3
4
5
6
7
8
9
0
2
0 inhibited the activity of hABDH16A by approximately 60%,
with 20 being selective. Altogether, we concluded that the
bulkiness of the substituent at position 2 of the thiazole ring
seems to be more relevant for the activity than its electron
donating or withdrawing ability.
We proceeded to study what substituents were tolerated at
position 2 of the thiazole ring. We synthesized the bulky phenyl
and chlorophenyl derivatives 15–17 with the methyl ester at
C18, according to Scheme 2. The chlorophenyl compounds 16
and 17 did not inhibit hABHD16A, and 15 was a modest
inhibitor.
The synthesis of the thiazolium salts 24–26, where the ring
nitrogen is no longer available for hydrogen bonding and is in
addition more prone to nucleophilic attack, was attempted next
(Scheme 3). Compound 18 and iodomethane or iodoethane,
respectively, were refluxed in acetone to give 24 and 25, in 73%
Scheme 2. Variation of the position 2 of the thiazole ring.
1
6
and 11% yield respectively. Compound 26 was obtained
similarly from 6 and iodomethane in 65% yield. None of the
thiazolium derivatives inhibited the activity of hABHD16A
significantly, which confirms that the thiazole ring is most
likely implicated in positioning of the compound in the enzyme
active site.
R
S
S
N
N
a
d
4
H
H
Scheme 3. Synthesis of the thiazolium salts 24−26
OMe
HO
O
R1
2N
R
I
R = Ph 15 (67%)
21 (36%)
S
S
R = 2-Cl-Ph 16 (66%)
R = 4-Cl-Ph 17 (43%)
R = Me 18 (72%)
R = COOEt 19 (22%)
R = CN 20 (46%)
N
R
b, c
a
e
H
H
OMe
OMe
S
N
S
N
O
O
R1 = Me, R2 = Me 24 (73%)
R1 = Me, R2 = Et 25 (11%)
R1 = H, R2 = Me 26 (65%)
R = H 6
R = Me 18
f
Reagents and conditions: (a) MeI or EtI, acetone, 56 ºC.
H
H
OH
NH2
O
O
We characterized in more detail the two most promising
hABHD16A inhibitors of the series, 18 and 20. The dose-
responses were determined using four concentrations (0.1-100
µM) of the compounds (Figure 2A). For reference purposes, the
potent hABHD16A inhibitor palmostatin B was tested at 0.01-
10 µM concentrations and in the present experiments it
22 (47%)
23 (77%)
Reagents and conditions: (a) Respective thioamide, dry EtOH,
20 ºC with microwaves. (b) 7 M NH in MeOH, r.t., 2 d. (c) Et N,
TFAA, THF, 0 ºC  r.t, 3 h. (d) LiAlH , THF, 0 ºC  r.t., 2 h. (e)
KOH, ethylene glycol, H O, 130 ºC, 1 d. (f) HOBt, EDC-HCl, aq.
NH , DMF, 0 ºC  r.t., 22 h.
1
3
3
4
2
3
inhibited hABHD16A with an IC50 value of 99 ± 12 nM (mean
6
±
SD, n=2) in close agreement with our previous findings. For
1
8 and 20, we determined the IC50 values (mean ± SD, n=2) of
Introduction of the less bulky methyl group at position 2 of the
thiazole ring resulted in 18, the most active compound in the set
with approximately 80% inhibition of the activity of
hABHD16A, and no inhibition of hABHD12 (Scheme 2). We
again ruled out the effect of having the methyl ester on ring A
by synthesizing the carboxylic acid and amide derivatives 22
and 23, respectively. Compound 23 was synthesized following
activation of 22 with hydroxybenzotriazole (HOBt) and N-(3-
3
.4 ± 0.2 µM and 5.2 ± 0.3 µM respectively. It is noteworthy
that in contrast to palmostatin B which comprehensively
inhibited hABHD16A in these assays, 18 and 20 could not fully
inhibit hABHD16A activity but 12 ± 1 % and 25 ± 1% residual
activity remained at 100 µM concentration, respectively.
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0
Figure 2. Biological characterization of 18 and 20 in comparison with palmostatin B. A: Dose-response curves for palmostatin B, 18 and 20
to inhibit 1-LG hydrolysis in lysates of hABHD16A-HEK cells. Lysates were pretreated for 30 min with DMSO (control) or with the
indicated concentrations of the inhibitors before adding the substrate (25 µM final concentration). Glycerol liberated from 1-LG hydrolysis
6
was determined as previously described. Note that in contrast to 10 µM palmostatin B, which comprehensively blocks 1-LG hydrolysis,
~20 % and ~30 % residual activity remains at 100 µM concentration of 18 and 20, respectively. Values are mean ±SD of duplicate wells
from two independent experiments. B–D: Reversible nature of hABHD16A inhibition by 18 and 20. Fast 40-fold dilution of inhibitor-treated
hABHD16A-HEK293 lysate preparation in the Reversibility Assay results in notable drop of the diterpene inhibitor potency, as compared
to potency values obtained using the Routine Assay. In contrast, the potency for the β-lactone palmostatin B remains similar during the time-
course of this study. Data are mean ± SD from two independent experiments. E: Competitive ABPP using rat cerebellar membrane proteome
reveals ABHD16A as the sole serine hydrolase targeted by 18 and 20. THL (10 µM), palmostatin B (10 µM) and Compound 44 (1 µM) were
6
used as positive controls to identify ABHD16A and in line with our previous study, all three blocked TAMRA-FP labeling of a band
migrating at ~63 kDa, corresponding to ABHD16A. Compound 18 dose-dependently inhibits TAMRA-FP labeling of ABHD16A whereas
2
0 was marginally effective only at the higher concentration. Note that in contrast to THL and palmostatin B, no additional targets are evident
for 18 or 20 among the metabolic serine hydrolases. The gel is representative of two independent ABPP runs with similar outcome. FAAH,
fatty acid amide hydrolase; LYPLA1/2, lysophospholipase A1/A2.
To test whether 18 and 20 reversibly inhibit hABHD16A, we
compared inhibitor potency obtained in the routine assays to
that obtained following rapid, 40-fold dilution of the enzyme-
active site thereby inhibiting subsequent labeling with the
active-site targeting probe. For reference purposes, the
previously characterized hABHD16A inhibitors THL,
8
6
inhibitor complex (Figure 2B–D). As the compounds showed
palmostatin B and compound 44 were included.
micromolar potency values in the routine assay, we extended
the inhibitor concentration range up to 1 mM concentration in
the dilution assays. A notable drop in inhibitor potency was
evident for 18 (11.4-fold) and 20 (6.4-fold), obviously due to
dissociation of the enzyme-inhibitor complex following the
dilution step. In contrast, the IC50 values for the reference
compound palmostatin B remained similar (1.8-fold change)
between the two assay formats, indicating that within the time-
frame of these studies, the β-lactone irreversibly inhibited
hABHD16A.
6
In line with previous findings, these experiments indicated that
the reference inhibitors totally blocked activity probe binding to
hABHD16A at the used concentrations (Figure 2E). As
previously shown, palmostatin B also inhibited probe labeling
of several additional serine hydrolases, most notably
LYPLA1/2 in this proteome. As 18 and 20 showed reversible
mode of inhibition in the glycerol-based hydrolase assays, these
compounds were tested at 20 and 200 µM concentrations
mimicking the approach that was successfully used to reveal
8
serine hydrolase targets for reversible inhibitors of ABHD12.
Next we probed selectivity of 18 and 20 among the serine
hydrolase in native rat brain membrane proteome. Competitive
ABPP was used to evaluate the hABHD16A selectivity of 18
and 20 among the serine hydrolases in rat cerebellar membrane
(Rcm) proteomes. We chose this proteome for these studies, as
a recent study indicated that in the rodent brain, hABHD16A
activity as revealed by the ABPP approach is higher in the
cerebellum as compared to cortex and hippocampus.3 In
competitive ABPP, binding of an inhibitor masks the enzyme's
Interestingly, hABHD16A was the only apparent target of 18 as
probe labeling of this particular serine hydrolase was dose-
dependently inhibited by the two concentrations of 18. In line
with less potent behavior in substrate-based activity assays, 20
targeted hABHD16A less efficiently, with clearly visible effect
only at 200 µM concentration. Interestingly, incomplete
inhibition of ABHD16A was also evident in ABPP experiments
using hABHD16A-HEK lysates (Figure S1), raising the
possibility that the observed incomplete inhibitory activity
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could derive from an allosteric rather than active site
mechanism of binding for these abietanes.
(2) Kawasaki, Y.; Zhang, L.; Cheng, J.-K.; Ji, R.-R. Cytokine
1
2
3
4
5
6
7
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Mechanisms of Central Sensitization: Distinct and Overlapping Role
of Interleukin-1β, Interleukin-6, and Tumor Necrosis Factor-α in
Regulating Synaptic and Neuronal Activity in the Superficial Spinal
Cord. J. Neurosci. 2008, 28 (20), 5189 LP-5194.
(3) Kamat, S. S.; Camara, K.; Parsons, W. H.; Chen, D. H.; Dix, M.
M.; Bird, T. D.; Howell, A. R.; Cravatt, B. F. Immunomodulatory
Lysophosphatidylserines Are Regulated by ABHD16A and ABHD12
Interplay. Nat. Chem. Biol. 2015, 11 (2), 164–171.
In summary, herein we have identified 12-thiazole abietanes as
a new class of reversible inhibitors of hABHD16A in vitro and
detailed key structure-activity relationships for enzyme
inhibition. The good selectivity of 18 for hABHD16A among
other serine hydrolyses warrants further investigations into this
class of compounds in search for more potent and equally
selective derivatives that will surely greatly contribute towards
translating the observed in vitro effects to an in vivo context,
thereby establishing the significance of inhibiting this enzyme
in neuroinflammation and inflammatory-mediated pain.
(4) Kim, H. Y. Phospholipids: A Neuroinflammation Emerging
Target. Nat. Chem. Biol. 2015, 11 (2), 99–100.
(5) Blankman, J. L.; Long, J. Z.; Trauger, S. A.; Siuzdak, G.; Cravatt,
B. F. ABHD12 Controls Brain Lysophosphatidylserine Pathways That
Are Deregulated in a Murine Model of the Neurodegenerative Disease
PHARC. Proc. Natl. Acad. Sci. 2013, 110 (4), 1500 LP-1505.
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(6) Savinainen, J. R.; Patel, J. Z.; Parkkari, T.; Navia-Paldanius, D.;
Marjamaa, J. J. T.; Laitinen, T.; Nevalainen, T.; Laitinen, J. T.
Biochemical and Pharmacological Characterization of the Human
Lymphocyte Antigen B-Associated Transcript 5 (BAT5/ABHD16A).
PLoS One 2014, 9 (10), 1–17.
ASSOCIATED CONTENT
Supporting Information
(
7) Navia-Paldanius, D.; Savinainen, J. R.; Laitinen, J. T.
The Supporting Information is available free of charge on the ACS
Publications website.
Biochemical and Pharmacological Characterization of Human α/β-
Hydrolase Domain Containing 6 (ABHD6) and 12 (ABHD12). J. Lipid
Res. 2012, 53 (11), 2413–2424.
Synthetic procedures, analytical data, assay protocols (PDF)
(8) Parkkari, T.; Haavikko, R.; Laitinen, T.; Navia-Paldanius, D.;
Rytilahti, R.; Vaara, M.; Lehtonen, M.; Alakurtti, S.; Yli-Kauhaluoma,
J.; Nevalainen, T.; Savinainen, J. R.; Laitinen, J. T. Discovery of
Triterpenoids as Reversible Inhibitors of α/β-Hydrolase Domain
Containing 12 (ABHD12). PLoS One 2014, 9 (5), e98286.
AUTHOR INFORMATION
Corresponding Author
(
9) Hügel, H. M.; Jackson, N. Danshen Diversity Defeating
Dementia. Bioorg. Med. Chem. Lett. 2014, 24 (3), 708–716.
10) Kolsi, L. E.; Krogerus, S.; Brito, V.; Rüffer, T.; Lang, H.; Yli-
*
Email: vania.moreira@helsinki.fi
(
Author Contributions
Kauhaluoma, J.; Silvestre, S. M.; Moreira, V. M. Regioselective
Benzylic Oxidation of Aromatic Abietanes: Application to the
Semisynthesis of the Naturally Occurring Picealactones A, B and C.
ChemistrySelect 2017, 2 (24), 7008–7012.
T.J.A. designed, synthesized and characterized the compounds
with the support of V.M.M. and J.Y.-K. J.R.S. and J.T.L.
performed the biological evaluation. The manuscript was written
through contributions of all authors.
(11) Burkhart, J. P.; Gates, C. A.; Laughlin, M. E.; Resvick, M. E.;
Peet, N. P. Inhibition of Steroid C17(20)Lyase with C-17-Heteroaryl
Funding Sources
Steroids. Bioorg. Med. Chem. 1996, 4 (9), 1411–1420.
(12) Rauwerdink, A.; Kazlauskas, R. J. How the Same Core
The research leading to these results has received funding from the
European Union Seventh Framework Programme (FP7/2007 -
Catalytic Machinery Catalyzes 17 Different Reactions: The Serine-
Histidine-Aspartate Catalytic Triad of α/β-Hydrolase Fold Enzymes.
ACS Catal. 2015, 5 (10), 6153–6176.
2
013) under grant agreement no 602919. J.T.L. acknowledges the
Academy of Finland (decision 278212) for funding support.
(13) Devine, S. M.; Mulcair, M. D.; Debono, C. O.; Leung, E. W.
W.; Nissink, J. W. M.; Lim, S. S.; Chandrashekaran, I. R.; Vazirani,
M.; Mohanty, B.; Simpson, J. S.; Baell, J. B.; Scammells, P. J.; Norton,
R. S.; Scanlon, M. J. Promiscuous 2-Aminothiazoles (PrATs): A
Frequent Hitting Scaffold. J. Med. Chem. 2015, 58 (3), 1205–1214.
(14) González, M. A.; Correa-Royero, J.; Agudelo, L.; Mesa, A.;
Betancur-Galvis, L. Synthesis and Biological Evaluation of Abietic
Acid Derivatives. Eur. J. Med. Chem. 2009, 44 (6), 2468–2472.
ACKNOWLEDGMENT
The authors acknowledge Ms. Taina Vihavainen and Mr. Juha
Niskanen (University of Eastern Finland) for conducting the
hydrolase assays and Adjunct Prof. Mikko Airavaara (Institute of
Biotechnology, HiLife Unit, University of Helsinki) for revising
the manuscript.
(15) Dang, Q.; Kasibhatla, S. R.; Jiang, T.; Fan, K.; Liu, Y.; Taplin,
F.; Schulz, W.; Cashion, D. K.; Reddy, K. R.; van Poelje, P. D.;
Fujitaki, J. M.; Potter, S. C.; Erion, M. D. Discovery of Phosphonic
Diamide Prodrugs and Their Use for the Oral Delivery of a Series of
Fructose 1,6-Bisphosphatase Inhibitors. J. Med. Chem. 2008, 51 (14),
4331–4339.
(16) Hojo, M.; Ichi, T.; Masuda, R.; Kobayashi, M.; Shibano, H.
Isolation and Reaction of New Aromatic Dications. 4-
Thioniapyridinium Dications: 2-aryl-(or 2-alkyl-)4-methyl-3-oxo-2H-
1,4-Thiazin-2-ylium Tetrafluoroborates. J. Org. Chem. 1988, 53 (10),
ABBREVIATIONS
ABHD, α,β-hydrolase domain; hABHD16A, human ABHD16A;
hABHD12, human ABHD12; PS, phosphatidylserine; ABPP,
activity-based protein profiling; THL, tetrahydrolipstatin; 1-LG, 1-
linoleylglycerol; FAAH, fatty acid amide hydrolase; LYPL,
lysophospholipase
REFERENCES
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1) Gao, Y.-J.; Ji, R.-R. Chemokines, Neuronal–glial Interactions,
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ABHD16A Lyso-PS ABHD12
Selective inhibition
H
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IC50 = 3.4 ± 0.2 µM
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