Synthesis and characterization of non-steroidal ligands for the glucocorticoid receptor: Selective quinoline derivatives with prednisolone-equivalent functional activity

Article abstract of DOI:10.1021/jm010228c

A novel class of functional ligands for the human glucocorticoid receptor is described. Substituents in the C-10 position of the tetracyclic core are essential for glucocorticoid receptor (GR) selectivity versus other steroid receptors. The C-5 position i

Full text of DOI:10.1021/jm010228c

J . Med. Chem. 2001, 44, 2879-2885
2879
Syn th esis a n d Ch a r a cter iza tion of Non -Ster oid a l Liga n d s for th e Glu cocor ticoid
Recep tor : Selective Qu in olin e Der iva tives w ith P r ed n isolon e-Equ iva len t
F u n ction a l Activity
Michael J . Coghlan,*,† Philip R. Kym,† Steven W. Elmore,† Alan X. Wang,† J ay R. Luly,† Denise Wilcox,†
Michael Stashko,† Chun-Wei Lin,† J effrey Miner,‡ Curtis Tyree,§ Masaki Nakane,† Peer J acobson,† and
Benjamin C. Lane†
Pharmaceutical Products Division, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois 60064, and
Departments of New Leads Discovery and Endocrine Research, Ligand Pharmaceuticals, Inc., 10255 Science Center Drive,
San Diego, California 92121
Received May 22, 2001
A novel class of functional ligands for the human glucocorticoid receptor is described.
Substituents in the C-10 position of the tetracyclic core are essential for glucocorticoid receptor
(GR) selectivity versus other steroid receptors. The C-5 position is derivatized with meta-
substituted aromatic groups, resulting in analogues with a high affinity for GR (Ki ) 2.4-9.3
nM) and functional activity comparable to prednisolone in reporter gene assays of glucocorticoid-
mediated gene transcription. The biological activity of these novel quinolines was also
prednisolone-equivalent in whole cell assays of glucocorticoid function, and compound 13 was
similar to prednisolone (po ED50 ) 2.8 mpk for 13 vs ED50 ) 1.2 mpk for prednisolone) in a
rodent model of asthma (sephadex-induced eosinophil influx).
Ch a r t 1
In tr od u ction
Glucocorticoids (GCs) have a pervasive role in human
health and physiology. The endogenous members of this
family, cortisol and cortisone (Chart 1), are involved in
a broad spectrum of endocrine functions including
metabolism of lipids, carbohydrates, and proteins, stress
response, fluid and electrolyte balance, as well as
maintenance of immunological, renal, and skeletal
homeostasis.1-5 Prompted by the isolation of GCs and
identification of their structures in the mid 1930s, a
monumental research effort in the 1940s and 1950s
resulted in the discovery of newer, more potent ana-
logues and an understanding of their biological proper-
ties, especially antiinflammatory effects. Prednisolone6
and dexamethasone7 emerged as benchmark drugs
during this era. Although GCs are associated with a
variety of clinical side effects, they are used for a
breadth of antiinflammatory therapies while the search
has continued for newer, more selective analogues.
Despite considerable chemical and biological investiga-
tions, an understanding of the exact mechanism of
action of these renowned molecules has only recently
been uncovered. The discovery and cloning of intracel-
lular receptors (IRs)8-10 demonstrated that steroids act
in association with specific members of this family. The
glucocorticoid receptor (GR)11 is a member of a rapidly
growing family of intracellular steroid receptors12 that
regulate gene transcription. GCs act as the natural
ligands for GR, and the resulting GR/ligand complex
(GRC) regulates gene expression. Other steroid recep-
tors such as estrogen (ER),13 progesterone (PR),14,15
mineralocorticoid (MR),16 and androgen (AR)17 also
regulate transcription as complexes with their natural
ligands, yet many of the natural and synthetic steroids
bind to more than one member of this receptor family.
This cross reactivity can result in undesired side ef-
fects: in the case of GCs, cross reactivity with MR, AR,
and PR can be problematic.18,19
The GRC regulates gene transcription by two modes
of action depicted in Figure 1.20 When a steroid or other
ligand L associates with GR in the cytosol, the resulting
GRC is transported into the nucleus where it can
regulate gene expression in either a monomeric or
dimeric form. The antiinflammatory effects of GRC are
believed to occur through the monomer, which adopts
a conformation possessing an affinity for existing tran-
* Address correspondence to this author: Michael J .Coghlan, Drop
Code 0528, Eli Lilly and Co., Lilly Corporate Center, Indianapolis, IN
46285. Phone:
317-651-1620. Fax:
317-433-3666. E-mail:
coghlan_michael@lilly.com.
† Abbott Laboratories.
‡ Department of Endocrine Research, Ligand Pharmaceuticals, Inc.
§ Department of New Leads Discovery, Ligand Pharmaceuticals, Inc.
10.1021/jm010228c CCC: $20.00 © 2001 American Chemical Society
Published on Web 08/02/2001

2880 J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 18
Coghlan et al.
Sch em e 1a
a
Reagents: (a) Pd(PPh3)2Cl2, Cs2CO3, DMF, 85 °C, 75%; (b)
BBr3, CH2Cl2, MeOH, 95%; (c) Cs2CO3, MeI, DMF, 99%; (d) H2,
10% Pd/C, dioxane, 98%; (e) I2, acetone, 105 °C, 45%.
F igu r e 1. Differential functions of monomeric and dimeric
glucocorticoid receptor/ligand complexes: repression and ac-
tivation.
pharmacophore for the family of steroid receptors, and
GR selectivity could be introduced in novel analogues.
Once GR-selective analogues are prepared, functional
equivalence to reference GCs could then be pursued in
reporter gene assays of repression as well as whole cell
models of GR function. Selective ligands with biological
profiles comparable to those of commercial steroids
could be tested in animal models of inflammation in
comparison with clinically used GCs.
Candidate GR ligands were prepared using a common
sequence of general procedures amenable to inclusion
of a variety of substituents in the D ring. A typical
example of this route is shown in Schemes 1 and 2 for
the C-10 methoxy analogues which began with the
assembly of the tetracyclic quinoline skeleton. Core
preparation and functionalization of the cores at C-5
was originally patterned after chemistry described
earlier.26 During the course of our efforts, we modified
several of these procedures, particularly the introduc-
tion of the aryl group at C-5, which resulted in improved
yields of analogous GR modulators. In the case of the
C-10 methoxy tetracycle, the synthesis began with a
modified Suzuki coupling of a known boronic acid with
commercially available methyl 2-bromo-5-nitrobenzoate
to deliver biphenyl compounds.
F igu r e 2. Structure of lead dihydroquinoline 1.
scription factors such as AP-121 or NFκB,22,23 thereby
repressing the transcription of proinflammatory cyto-
kines and other inflammatory mediators.24 The repres-
sion of proinflammatory agents via monomeric GRC is
believed to be the primary mechanism for the antiin-
flammatory and immunosuppressive effects of GCs.25
Dimeric GRCs behave as conventional steroid receptor/
ligand transcription factors. These dimers adopt specific
conformations that allow them to bind directly to
particular DNA sequences called glucocorticoid response
elements (GREs). When the GRC dimer binds to a GRE,
gene activation occurs via stabilization of the transcrip-
tional machinery at the start site of the promoter. GRC
dimers are the endogenous transcription factors which
associate with GREs, and most of the endogenous
functions from transcriptional activation of GRC dimers
are related to routine endocrine and metabolic pro-
cesses.
The electron-rich boronic acid 2 derived from resor-
cinol dimethyl ether27,28 reacted with commercially
available methyl 2-bromo-5-nitrobenzoate 329 in the
presence of dichlorobis(triphenylphosphine)palladium-
(II) and cesium carbonate30,31 to form the sterically
hindered biphenyl ester 4 in high yield. Treatment of
ester 4 with boron tribromide resulted in an efficient
cleavage of the methoxy groups followed by spontaneous
lactonization to the phenolic benzocoumarin, which was
then alkylated with methyl iodide in the presence of
cesium carbonate to provide the methyl ether 5. The
nitroarene functionality of ether 5 was reduced using
catalytic hydrogenation to provide aniline 6 in high
yield. The amino group of this benzocoumarin was then
converted to the 1,2-dihydro-2,2,4-trimethylquinoline 7
by treatment with acetone and iodine via a modified
Skraup ring annulation.32-34
To date there are no reported antiinflammatory, GR-
specific nonsteroidal ligands that mimic GC function at
the molecular level. We report the synthesis and bio-
logical characterization of novel, nonsteroidal GR-selec-
tive ligands whose functional activity is equivalent to
prednisolone.
Ch em istr y
Our interest began with the disclosure of novel PR
ligands which were cross-reactive with GR.26 Quinoline
analogues such as 1 (Figure 2) did not possess the
desired degree of receptor selectivity. Moreover, they
were inferior in assays of GR-mediated transcription
when compared to reference standards such as dexam-
ethasone or prednisolone.26 However, we surmised that
this novel tetracyclic core structure could be a general
With the tetracyclic benzocoumarin cores in hand, the
task of functionalization at C-5 was undertaken. Three
methods that were commonly used are shown in Scheme
2. Originally, method A involved organolithium addition
to the C-5 carbonyl followed by reduction of the resulting
hemiketal with triethysilane and BF3 etherate or tri-

Synthesis of Glucocorticoid Receptor Ligands
J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 18 2881
Sch em e 2a
a
Reagents for Method A: (i) ArLi, THF, -78 °C; (ii) Et3SiH, BF3‚OEt2, CH2Cl2. Method B: (i) DIBAL, CH2Cl2; (ii) MeOH, H+; (iii)
ArMgX, BF3‚OEt2, CH2Cl2. Method C: (i) DIBAL, CH2Cl2; (ii) ArOH, MgSO4; (iii) ArMgX, toluene.
fluoroacetic acid. Since this protocol gave satisfactory
results with a limited number of core tetracycles, we
turned to an alternative strategy involving a C-5 methyl
acetal (method B) prepared by reduction of the C-5
lactone to the lactol followed by acetal formation under
mild acid catalysis. The methyl acetals reacted smoothly
with aryl Grignard reagents in the presence of Lewis
acid catalysts such as BF3 etherate. During this proce-
dure, a deep green acetal/BF3 complex develops at low
temperature, and the reaction can be monitored by
colorimetric titration during addition of solutions of
arylmagnesium halides in ether to deliver the desired
C-5 aryl analogues in high yields.
Although the acetal/BF3 chemistry provided an as-
sortment of derivatives, polar contaminants in the
reaction such as small quantities of THF quenched the
acetal/BF3 complex, resulting in no desired product and
recovery of starting acetal or lactol arising from hy-
drolysis. Method C was useful in those cases where the
organometallic reagents were prepared in THF or where
the polarity of the medium precluded methyl acetal/BF3
complex formation. This method employs substituted
phenoxy acetals, which are prepared with assorted
phenols under mild acid catalysis. In many cases, these
crystalline phenyl acetals were isolated and used with-
out further purification. Phenyl acetals were treated
directly with aryl organometallic reagents35 to provide
the desired C-5 aryl compounds. Overall, methods A,
B, and C provided a breadth of candidate GR modulators
for assessment in commendable yields.
binding assays were similarly run using tritiated proges-
terone, aldosterone, testosterone, and estradiol, respec-
tively.
F u n ction a l Activity. Although many compounds
bind to GR, there are no reported nonsteroidal ligands
for this receptor whose actions as repressors or activa-
tors of transcription are comparable with natural or
synthetic glucocorticosteroids. We sought analogues
equivalent in repression and activation to natural
(cortisone, cortisol) or commercial (prednisolone) gluco-
corticoids. To assess the functional activity of candidate
GR ligands, we employed a reporter gene cotransfection
assay along with relevant assays of repression and
activation in unaltered native cell lines. Cotransfection
is routinely employed to characterize the interaction of
a small molecule ligand of intracellular receptors. A pair
of plasmids containing the IR of interest and a reporter
gene construct is used to prepare transiently transfected
mammalian cells that do not endogenously express the
receptor under study. The plasmid encoded for the
specified receptor is constitutively expressed, whereas
the reporter plasmid is under the control of the same
receptor-mediated promoter which lies upstream of
cDNA for firefly luciferase, producing a quantifiable
output upon receptor-mediated gene expression. Studies
run in native cell lines were typically done for validation
of the cotransfection data using unaltered cells which
have been employed in steroid-mediated models of
repression and activation.
Rep r ession . The E-selectin assay is the cotransfec-
tion assay used to evaluate the repression activity of
candidate GR ligands. This method uses a portion of
the E-selectin promoter region that contains one copy
of each of the AP-1 and NFκB sites. This segment of
DNA has no known GREs, thereby reducing concerns
about differentiating responses from repression versus
activation mediated by monomeric or dimeric GRC. This
construct is placed upstream of a luciferase gene
expression vector in the HEP G2 cell line. Human GR
is then transiently transfected into these cells, and
Biology
Recep tor Selectivity/Bin d in g Assa ys. Assessment
of the binding affinity for steroidal IRs was done
following published procedures.36 For GR binding as-
says, tritiated dexamethasone, human GR, and test
compounds were incubated, and specific binding was
determined as the difference between binding of [3H]-
dexamethasone in the absence and in the presence of 1
µM unlabeled dexamethasone. PR, MR, AR, and ER

2882 J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 18
Coghlan et al.
Ta ble 1. Receptor Binding Data: C-10 Substitution Improves
GR Selectivity
stimuli such as interleukin-1 (IL-1) or tumor necrosis
factor (TNF) are used to induce expression of luciferase
via the transfected E-selectin promoter construct. In the
presence of repressors such as prednisolone or other
functional GR ligands, expression of luciferase declines
and this decrease is quantified. Internal standards such
as prednisolone and dexamethasone are used to set a
range of efficacy, and other commercial GCs are assayed
for comparison with candidate GR ligands. Maximal
efficacies of compounds are reported as a percentage of
the maximal response observed for dexamethasone, and
potency values are calculated as the concentration at
half-maximal response for these curves.
binding Ki (nM)a
compd
R
GR
PR
1
8
9
9-Cl
9.3 ( 2.2
53 ( 11
c
8-OMe
9-OMe
10-OMe
1800b
-
18 ( 3.9
4.7 ( 0.70
390 ( 40
-
10
Although the E-selectin reporter gene assay provides
a direct assessment of the functional activity of GR
ligands, additional measures of repression in unaltered
native cell lines with immunologically relevant end-
points were also followed. Glucocorticoids have been
shown to inhibit the production of IL-1-induced IL-6
expression in human fibroblasts.37 This effect has been
shown to occur by way of a GR-mediated mechanism at
the transcriptional level in native human cells, and
conventional glucocorticoids effectively repress IL-6
production in this system.38,39 Production of this cyto-
kine is associated with proliferation of B and T cell lines,
and circulating IL-6 levels increase in common inflam-
matory diseases such as rheumatoid arthritis.40 Since
gene expression associated with production of this
cytokine represents another potential mechanism for
the antiinflammatory effect of the steroidal ligands with
GR, we employed IL-1-induced IL-6 expression in the
native cell line to assess our novel GR ligands for
functionality.
a
Mean values of at least three experiments done in triplicate
b
with standard errors. One experimental determination done in
triplicate. c A hyphen indicates that the mean Ki values of at least
three experiments were >5000 nM. Standard errors were not
determined.
evaluate candidate GC ligands. In this experiment,
sephadex beads are injected into the circulatory system,
and the eosinophil influx into the lungs resulting from
accumulation of the beads is measured by bronchoal-
veolar lavage (BAL). Reduction of eosinophil influx is
assessed for candidate analogues in comparison with
prednisolone, dexamethasone, and untreated controls.
Resu lts a n d Discu ssion
GR Selectivity. Since lead compound 1 also has an
affinity for PR, we initially sought to optimize GR
selectivity while minimizing PR cross reactivity. Instal-
lation of a substituent at C-10 of the core provided GR-
selective analogues with very little affinity for PR. This
trend is shown in Table 1 for the D ring methoxy
analogues versus compound 1. As the position of the
methoxy group is moved around the D ring, GR binding
and receptor selectivity are optimal for C-10 methoxy
analogue 10. Introduction of a variety of C-10 substit-
uents suggests that this is a general trend for smaller
substituents with the added benefit of improved activity
on functional assays compared with prednisolone (see
below). Binding assays with the remaining steroid
receptors MR, AR, and ER (Table 2) demonstrated that
this core modification provided GR-specific ligands with
a breath of substituted phenyl groups at C-5.
F u n ction a l Liga n d s for th e Glu cocor ticoid Re-
cep tor . Once GR-selective ligands had been prepared,
we began to assess whether the resulting GRCs had
favorable functional profiles. Our earliest investigations
involved modification of substituents on the C-5 phenyl
group on the GR-selective 10-methoxy core. We found
that modification of the aryl substituents provided a
remarkable number of active compounds. A representa-
tive group of these GR ligands is depicted in Tables 3
and 4. Modification of the aryl ring provided analogues
that were prednisolone-equivalent in efficacy with com-
parable potency in in vitro models of repression and
activation.
Activa tion . In the cotransfection assay for transcrip-
tional activation via GREs,41,42 the receptor plasmid
containing hGR is introduced under the control of a
constitutive promoter from the Rous sarcoma virus long
terminal repeat. The reporter plasmid is a portion of
the mouse mammary tumor virus (MMTV) promoter
which lies upstream of a luciferase gene expression
vector in CV-1 cells. The MMTV promoter contains four
GRE sites, and the entire construct has no known
affinity for AP-1 or NFκB. GR ligands will initiate
luciferase gene expression using dimeric GRC interac-
tions with these sites in the MMTV promoter. Maximal
efficacy and potency values of compounds in this GRE
activation assay are reported using dexamethasone as
described for the repression assays above.
GR-mediated activation was also evaluated in unal-
tered human skin fibroblasts using standard assays
employed for traditional glucocorticoids. Of the methods
employed, measurement of the enzymatic activity of
aromatase induced by GRE activation was selected. The
aromatase assay is a biochemical method for measuring
the enzymatic conversion of 3H-androstenedione to
estrogens. This process produces tritiated water as a
byproduct which is then quantified using the same
standards (dexamethasone and prednisolone) to deter-
mine maximal efficacy and potency.
Modification at the meta position of the ring provided
a group of functional GR ligands. Although prototype
quinoline 1 was uniformly inactive in evaluation of GR-
mediated function, compounds 12 and 13 are among the
best of these ligands with a profile in reporter gene
assays comparable to prednisolone.
In Vivo. Glucocorticoids greatly reduce lung eosino-
phil influx in asthma, and animal models that quantify
this effect are commonly used as measures of effective-
ness for this condition. We chose a sephadex-induced
lung eosinophil influx in Brown Norway rats43 to

Synthesis of Glucocorticoid Receptor Ligands
J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 18 2883
Ta ble 2. Receptor Binding Data: Cross-Reactivity with Steroid Hormone Receptorsa
Ki (nM)
MR
compd
R
R′
GR
PR
AR
ERd
1
9-Cl
H
H
9.3 ( 2.2
4.7 ( 0.70
11 ( 2.7
2.4 ( 0.33
4.0 ( 0.84
2.4 ( 0.28
53 ( 11
1100 ( 57
1682 ( 850
493 ( 96
3914 ( 16
3838 ( 63
37 ( 12
1400 ( 6.4
2660 ( 420
3360 ( 340
3066 ( 130
3115 ( 99
2762c
‡
‡
‡
‡
‡
‡
b
10
11
12
13
10-OMe
10-OMe
10-OMe
10-OMe
-
3′-CF3
3′-OC(O)NMe2
3′-OCH2SMe
4000 ( 1300
-
-
-
prednisolone
a
b
Mean Ki values of at least three experiments done in triplicate with standard errors. A hyphen indicates that the mean Ki values
of at least three experiments were >5000 nM. Standard errors were not determined. c Mean values of two experiments done in triplicate
d
with standard deviations. ‡ indicates that the mean Ki values of at least three experiments were >1000 nM. Standard errors were not
determined.
Ta ble 3. Functional Repression of GR Ligandsa
Ta ble 4. Functional Activation of GR Ligandsa
GRE cotransfection assay
MMTV
native cell assay
aromatase
potency
potency
(IC50,nM)
( SEM
efficacy
(%dex)
(IC50,nM) efficacy
(SEM (% dex)
compd
prednisolone
8.0 ( 1.1
300 ( 41
44 ( 4.0
12 ( 4.0
9.0 ( 0.97
28 ( 5.7
29 ( 10
10 ( 0.58
107 ( 36
24 ( 3.5
89
17
110
78
85
109
98
57
97
110
41 ( 6.0
164 ( 86
105 ( 1.1
216 ( 63
140 ( 19
131 ( 16
314 ( 168
56 ( 27
85
18
52
74
102
30
19
90
82
45
10
11
12
13
14
15
16
17
18
cotransfection assay
E-selectin
native cell assay
IL-6
potency
potency
(IC50, nM) efficacy (IC50, nM) efficacy
compd
R′
( SEM
(% dex)
( SEM
(% dex)
prednisolone
2.1 ( 0.18
123 ( 40
57 ( 33
98
83
93
100
100
91
92
96
94
94
3.8 ( 0.16
51 ( 0.19
32 ( 0.086
26 ( 0.14
16 ( 0.17
49 ( 0.12
12 ( 0.061
11 ( 0.071
16 ( 0.11
9.2 ( 0.061
95
62
87
92
97
77
91
91
94
90
139 ( 29
146 ( 41
10
11
12
13
14
15
16
17
18
H
3-CF3
a
Mean values of at least three experiments done in triplicate
with standard errors. All IC50 values were determined from full
seven-point, half log concentration-response curves. Efficacies are
shown using dexamethasone as the standard (100%). Standard
errors for all efficacy values were ) < 10%.
3-OC(O)NMe2 6.0 ( 0.89
3-OCH2SMe
3-OCH2OMe
3-Br-5-Me
3,5-di F
3,5-di Cl
3,5-di Me
4.0 ( 0.89
23 ( 7.8
18 ( 2.8
9 ( 2.8
67 ( 25
18 ( 2.8
Ta ble 5. Ligand Binding and Repression Data for Optical
Isomers of GR Modulatorsa
a
Mean values of at least three experiments done in triplicate
native cell assay
IL-6
with standard errors. All IC50 values were determined from full
seven-point, half log concentration-response curves. Efficacies are
shown using dexamethasone as the standard (100%). Standard
errors for all efficacy values were ) < 10%.
binding Ki
(nM) ( SEM
potency
(IC50,nM) efficacy
sign of
compd rotation
GR
PR
( SEM
(% dex)
b
The presence of the C-5 stereogenic center in these
selective GR ligands prompted the separation of two of
the racemates, 10 and 17, into their respective antipodes
by HPLC. As shown in Table 5, the (-) enantiomers
were equivalent to their corresponding racemates in GR
binding and in vitro models of repression. The (-)
compounds clearly showed superior efficacy and potency
when compared to the (+) analogues, which were much
less active in all assays examined. This biological
preference for levorotatory isomers has also been ob-
served for a closely analogous series of PR modulators
where the (-) isomer was determined to have the ‘S’
absolute stereochemistry.44 By analogy, the (-) isomers
in this series are also believed to have the ‘S’ configu-
ration.
10
19
20
17
21
22
(
+
-
(
+
-
4.7 ( 0.70
240 ( 24
2.1 ( 0.40
7.1 ( 3.2
95 ( 4.9c
-
59 ( 0.19
-
30 ( 0.51
16 ( 0.11
-
62
-
-
-
-
-
77
94
-
3.3 ( 0.53c 1560 ( 1100c 1.3 ( 0.076
70
a
Mean values of at least three experiments done in triplicate
with standard errors. All IC50 values were determined from full
seven point, half log concentration-response curves. Efficacies are
shown using dexamethasone as the standard (100%). Standard
b
errors for all efficacy values shown were ) < 10%. A hyphen
indicates that the mean Ki values of at least three experiments
were >5000 nM, a functional potency that was not calculated due
to low efficacy, or a functional efficacy <20%. Standard errors were
not determined for hyphenated entries. c Mean values of two
experiments done in triplicate with standard deviations.
influx assay. Several of the dihydroquinolines described
above were tested and, of the examples described
here,compound 13 was comparable to prednisolone
(ED50 ) 2.8 mpk for 13 vs 1.2 mpk for prednisolone).
We examined in vivo models of inflammation to
determine whether the functional activity observed in
vitro was suggestive of antiiflammatory activity in
animal models of asthma such as the rat eosinophil

2884 J ournal of Medicinal Chemistry, 2001, Vol. 44, No. 18
Coghlan et al.
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Con clu sion
A novel series of nonsteroidal, GR-selective ligands
was discovered that mimic the functional effects of
conventional glucocorticoids. The novel tetracyclic quin-
oline core represents a novel scaffold that provides
functional ligands for the family of steroid receptors.
Receptor binding as well as assays of activation and
repression using cotransfected and native cell lines has
enabled the characterization of a novel series of 10-
substituted 5-aryl-1,2-dihydro-2,2,4-trimethyl-5H-chro-
meno-[3,4-f]quinolines that are comparable to predniso-
lone. The 10-substituent was the key for GR selectivity,
and in vitro assays of these analogues demonstrated
that meta-substituted C-5 phenyl analogues were com-
parable to GCs in GR-mediated function. Upon oral
administration, compound 13 was comparable to pred-
nisolone in a rodent in vivo model of asthma. To the
best of our knowledge, this is the first report of nonste-
roidal GR-selective ligands whose functional profile
mimics those of natural glucocorticoids. This exciting
result is currently under intense investigation aimed
at separation of GR-mediated activation from repres-
sion. More comprehensive discussions of this SAR will
be published in separate reports as well as other
investigations of the in vitro and in vivo effects of this
novel class of selective ligands for the glucocorticoid
receptor.
Su p p or tin g In for m a tion Ava ila ble: Detailed descrip-
tions of reaction conditions, compound characterization data,
and assay protocols are available free of charge via the Internet
at http://acs.org.
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