The M1 muscarinic acetylcholine receptor is
to play an important role in memory and cognition, making it a potential
target for the treatment of Alzheimer’s disease (AD) and schizophrenia.
Moreover, M1 interacts with BACE1 and regulates its proteosomal
degradation, suggesting selective M1 activation could afford
both palliative cognitive benefit as well as disease modification
in AD. A key challenge in targeting the muscarinic acetylcholine receptors
is achieving mAChR subtype selectivity. Our lab has previously reported
the M1 selective positive allosteric modulator ML169. Herein
we describe our efforts to further optimize this lead compound by
preparing analogue libraries and probing novel scaffolds. We were
able to identify several analogues that possessed submicromolar potency,
with our best example displaying an EC50 of 310 nM. The
new compounds maintained complete selectivity for the M1 receptor over the other subtypes (M2–M5), displayed improved DMPK profiles, and potentiated the carbachol
(CCh)-induced excitation in striatal MSNs. Selected analogues were
able to potentiate CCh-mediated nonamyloidogenic APPsα release,
further strengthening the concept that M1 PAMs may afford
a disease-modifying role in the treatment of AD.
Muscarinic; acetylcholine; positive allosteric
modulator (PAM); ML169; Alzheimer’s disease
(AD); medium spiny neurons (MSNs); MLPCN
Herein we describe the discovery and development of a novel class of M4 positive allosteric modulators, culminating in the discovery of ML293. ML293 exhibited modest potency at the human M4 receptor (EC50 = 1.3 µM) and excellent efficacy as noted by the 14.6-fold leftward shift of the agonist concentration-response curve. ML293 was also selective versus the other muscarinic subtypes and displayed excellent in vivo PK properties in rat with low IV clearance (11.6 mL/min/kg) and excellent brain exposure (PO PBL, 10 mg/kg at 1 h, [Brain] = 10.3 µM, B:P = 0.85).
Positive allosteric modulator; M4; ML293; CNS penetration; Muscarinic receptor 4
A series of novel indomethacin analogues with carbaboranes as three-dimensional substitutes for the chlorophenyl ring have been prepared. Their cyclooxygenase (COX) inhibition and enzyme selectivity has been tested and compared to the corresponding adamantyl analogues. Surprisingly, only the ortho-carbaborane derivatives were active compounds. Preliminary biological studies gave an interesting insight into the validity of employing carbaboranes as pharmacophores.
Carbaborane; Carborane; Cyclooxygenase; Indomethacin; Nonsteroidal anti-inflammatory drugs
Herein we report the discovery and SAR of a novel metabotropic glutamate receptor 3 (mGlu3) NAM probe (ML289) with 15-fold selectivity versus mGlu2. The mGlu3 NAM was discovered via a ‘molecular switch’ from a closely related, potent mGlu5 positive allosteric modulator (PAM), VU0092273. This NAM (VU0463597, ML289) displays an IC50 value of 0.66 μM and is inactive against mGlu5. 2012
metabotropic glutamate receptor 3; mGlu3; molecular switch; NAM
There is an increasing amount of literature data showing the positive effects on preclinical anti-Parkinsonian rodent models with selective positive allosteric modulators of metabotropic glutamate receptor 4 (mGlu4).1 However, most of the data generated utilize compounds that have not been optimized for drug-like properties and, as a consequence, they exhibit poor pharmacokinetic properties and thus do not cross the blood-brain barrier. Herein, we report on a series of N-4-(2,5-dioxopyrrolidin-1-yl)-phenylpicolinamides with improved PK properties with excellent potency and selectivity as well as improved brain exposure in rodents. Finally, ML182 was shown to be orally active in the haloperidol induced catalepsy model, a well-established anti-Parkinsonian model.
metabotropic glutamate receptors; mGlu4; positive allosteric modulators; Parkinson’s disease; haloperidol-induced catalepsy; structure-activity relationship (SAR); oral efficacy; brain penetration
Nonsteroidal anti-inflammatory drugs (NSAIDs) exert their pharmacological activities by inhibiting cyclooxygenase (COX)-1 and COX-2. Previous studies have shown that esters and amides of non-selective inhibitors such as indomethacin are selective against COX-2, which is the therapeutically relevant isoform. Structure-activity analysis indicates that substituted phenyl rings are tolerated as ester components. In the present study, the introduction of inorganic ortho- and meta-carbaborane moieties was explored with the aim to create COX-2 inhibitors and more importantly to investigate the validity of using these boron clusters as drug entities. Interestingly, only the ortho-carbaborane ester was active whereas the meta isomer was not. A similar lack of inhibitory potency was observed when an adamantyl substituent or alkylene spacers at the carbaborane were introduced in the ester functionality.
Carborane; Carbaborane; Cyclooxygenase; Indomethacin; Nonsteroidal anti-inflammatory drugs
Herein we report the discovery, synthesis and evaluation of a series of N-(4-acetamido)-phenylpicolinamides as positive allosteric modulators of mGlu4.a Compounds from the series show submicromolar potency at both human and rat mGlu4. In addition, pharmacokinetic studies utilizing subcutaneous dosing demonstrated good brain exposure in rats.
Effective diagnosis of inflammation and cancer by molecular imaging is challenging because of interference from non-selective accumulation of the contrast agents in normal tissues. Here we report a series of novel fluorescence imaging agents that efficiently target cyclooxygenase-2 (COX-2), which is normally absent from cells, but is found at high levels in inflammatory lesions, and in many premalignant and malignant tumors. After either intraperitoneal or intravenous injection, these reagents become highly enriched in inflamed or tumor tissue compared to normal tissue and this accumulation provides sufficient signal for in vivo fluorescence imaging. Further, we show that only the intact parent compound is found in the region of interest. COX-2-specific delivery was unambiguously confirmed using animals bearing targeted deletions of COX-2 and by blocking the COX-2 active site with high affinity inhibitors in both in vitro and in vivo models. Because of their high specificity, contrast, and detectability, these COX-2 beacons are ideal candidates for detection of inflammatory lesions or early-stage COX-2-expressing human cancers, such as those in the esophagus, oropharynx, and colon.
Cyclooxygenase-2; Molecular Imaging; Targeted; Fluorescence; Inflammation; Premalignancy
Sulindac sulfide is a benzylidene-indene that is a potent, time-dependent inhibitor of cyclooxygenases-1 and -2. Removal of the 2′-methyl group from the indene ring dramatically reduces time-dependent inhibition of both enzymes but also changes the geometry of the benzylidene double bond from Z to E. Herein, we explore the importance of double bond geometry on cyclooxygenase inhibition. The Z-isomer of 2′-des-methyl sulindac sulfide was synthesized by reduction of a bromoindene precursor or by photoisomerization of the E-isomer. The Z-isomer inhibited both cyclooxygenases, but with diminished potency compared to sulindac sulfide. Thus, although the 2′-methyl group is a major determinant of time-dependent cyclooxygenase inhibition, the geometry of the benzylidene double bond plays a role as well.
COX inhibition; photoisomerization; NSAIDs; 2′-des-methyl sulindac sulfide
Herein we report a next generation muscarinic receptor 4 (M4) positive allosteric modulator (PAM), ML253 which exhibits nanomolar activity at both the human (EC50 = 56 nM) and rat (EC50 = 176 nM) receptors and excellent efficacy by the left-ward shift of the ACh concentration response curve (Fold Shift, human = 106; rat = 50). In addition, ML253 is selective against the four other muscarinic subtypes, displays excellent CNS exposure and is active in an amphetamine-induced hyperlocomotion assay.
Muscarinic receptor 4; Positive allosteric modulator; Amphetamine induced hyperlocomotion; CNS; PAM
Prostaglandins (PGs) are powerful lipid mediators in
and pathophysiological responses. They are produced by oxidation of
arachidonic acid (AA) by cyclooxygenases (COX-1 and COX-2) followed
by metabolism of endoperoxide intermediates by terminal PG synthases.
PG biosynthesis is inhibited by nonsteroidal anti-inflammatory drugs
(NSAIDs). Specific inhibition of COX-2 has been extensively investigated,
but relatively few COX-1-selective inhibitors have been described.
Recent reports of a possible contribution of COX-1 in analgesia, neuroinflammation,
or carcinogenesis suggest that COX-1 is a potential therapeutic target.
We designed, synthesized, and evaluated a series of (E)-2′-des-methyl-sulindac sulfide (E-DMSS) analogues for inhibition of COX-1. Several potent
and selective inhibitors were discovered, and the most promising compounds
were active against COX-1 in intact ovarian carcinoma cells (OVCAR-3).
The compounds inhibited tumor cell proliferation but only at concentrations
>100-fold higher than the concentrations that inhibit COX-1 activity. E-DMSS analogues may be useful probes of COX-1 biology in
vivo and promising leads for COX-1-targeted therapeutic agents.
Indomethacin is a potent, time-dependent,
of the cyclooxygenase enzymes (COX-1 and COX-2). Deletion of the 2′-methyl
group of indomethacin produces a weak, reversible COX inhibitor, leading
us to explore functionality at that position. Here, we report that
substitution of the 2′-methyl group of indomethacin with trifluoromethyl
produces CF3–indomethacin, a tight-binding inhibitor
with kinetic properties similar to those of indomethacin and unexpected
COX-2 selectivity (IC50 mCOX-2 = 267 nM; IC50 oCOX-1 > 100 μM). Studies with site-directed mutants reveal
that COX-2 selectivity results from insertion of the CF3 group into a small hydrophobic pocket formed by Ala-527, Val-349,
Ser-530, and Leu-531 and projection of the methoxy group toward a
side pocket bordered by Val-523. CF3–indomethacin
inhibited COX-2 activity in human head and neck squamous cell carcinoma
cells and exhibited in vivo anti-inflammatory activity in the carrageenan-induced
rat paw edema model with similar potency to that of indomethacin.
Cyclooxygenase; inflammation; nonsteroidal
anti-inflammatory drug; coxib; prostaglandin; arachidonic acid