In this paper we describe the synthesis of a series of alpha-substituted analogues of the potent and selective group II metabotropic glutamate receptor (mGluR) agonist (1S,1'S,2'S)-carboxycyclopropylglycine (2, L-CCG 1). Incorporation of a substitutent on the amino acid carbon converted the agonist 2 into an antagonist. All of the compounds were prepared and tested as a series of four isomers, i.e., two racemic diastereomers. On the basis of the improvement in affinity realized for the alpha-phenylethyl analogue 3, in this paper we explored the effects of substitution on the aromatic ring as a strategy to increase the affinity to these compounds for group II mGluRs. Affinity for group II mGluRs was measured using [3H]glutamic acid (Glu) binding in rat forebrain membranes. Antagonist activity was confirmed for these compounds by measuring their ability to antagonize (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid-induced inhibition of forskolin stimulated cyclic-AMP in RGT cells transfected with human mGluR2 and mGluR3. Meta substitution on the aromatic ring of 3 with a variety of substituents, both electron donating (e.g., methyl, hydroxy, amino, methoxy, phenyl, phenoxy) and electron withdrawing (e.g., fluorine, chlorine, bromine, carboxy, trifluoromethyl) gave from 1.5- to 4.5-fold increases in affinity. Substitution with p-fluorine, as in 97 (IC50 = 0.022 +/- 0.002), was the exception. Here, a greater increase in affinity was realized than for either the ortho- or meta-substituted analogues; 97 was the most potent compound resulting from monosubstitution of the aromatic. At best, only modest increases in affinity were realized for certain compounds bearing either two chlorines or two fluorines, and two methoxy groups gave no improvement in affinity (all examined in a variety of substitution patterns). Three amino acids, 4, 5, and 104, were resolved into their four constituent isomers, and affinity and functional activity for group II mGluRs was found to reside solely in the S,S,S-isomers of each, consistent with 1. With an IC50 = 2.9 +/- 0.6 nM, the resolved xanthylmethyl compound 168 was the most potent compound from this SAR. Amino acid 168 demonstrated high plasma levels following intraperitoneal (i.p.) administration and readily penetrated into the brain. This compound, however, had only limited (approximately 5%) oral bioavailability. Systemic administration of 168 protected mice from limbic seizures produced by the mGluR agonist 3,5-dihydroxyphenylglycine, with an ED50 = 31 mg/kg (i.p., 60 min preinjection). Thus, 168 represents a valuable tool to study the role of group II mGluRs in disease.

Amino diacid 3, a highly selective competitive GluR5 kainate receptor antagonist, exhibited high GluR5 receptor affinity and selectivity over other glutamate receptors. Its diethyl ester prodrug 4 was orally active in two models of migraine: the neurogenic dural plasma protein extravasation model and the nucleus caudalis c-fos expression model. These data suggest that a GluR5 kainate receptor antagonist might be an efficacious antimigraine therapy with a novel mechanism of action.

ABSTRACT:In an effort to develop a novel therapeutic agent aimed at addressing the unmet need of patients with osteoarthritis pain, we set out to develop an inhibitor for autotaxin with excellent potency and physical properties to allow for the clinical investigation of autotaxin-induced nociceptive and neuropathic pain. An initial hit identification campaign led to an aminopyrimidine series with an autotaxin IC 50 of 500 nM. X-ray crystallography enabled the optimization to a lead compound that demonstrated favorable potency (IC 50 = 2 nM), PK properties, and a robust PK/PD relationship. KEYWORDS: Autotaxin, tool molecule, osteoarthritis, LPA O steoarthritis (OA) is a highly prevalent disease affecting many adults including more than one out of three individuals aged 65 or older in the United States.1 In addition to significant accompanying pain, OA frequently leads to pronounced disability resulting in the loss of work, hospitalization, and joint replacement procedures.2 Current first-line pharmacological treatment options for OA focus on reducing inflammation and the associated pain. Nonsteroidal antiinflammatory drugs (NSAIDS) and selective COX-2 inhibitors are among the most prescribed medications for OA pain but unfortunately are also frequently accompanied by gastrointestinal, renal, and CV side effects, limiting their use. 3 Recently, the role of lyosophosphatidic acid (LPA) in certain inflammatory conditions has been studied. 4 LPA exists as a number of molecular species that have variable saturated and unsaturated fatty acid chains.5 Signaling of LPA through six GPCRs (LPA Receptors 1−6) has been shown to lead to the upregulation of inflammatory cytokines and matrix metalloproteinases, which contribute to the pathogenesis of OA. 6LPA signaling has also been associated with many other pathologies, such as pulmonary fibrosis and cancer. In vivo, the enzyme autotaxin (ATX), with lyosophosopholipase D activity, is the primary source of extracellular LPA, which results from the cleavage of choline from lysophosphatidylcholine (LPC) (Figure 1). LPA is also produced through action of secreted phospholipases A2 (sPLA2) on phosphatidic acid (PA), although this is believed to be a minor route of extracellular LPA production in vivo. 8,9 Autotaxin is an extracellular, 125 kDa protein that was originally characterized in 1993 by Stracke et al. as a motility stimulating protein. 10 In 2002, Umezu-Goto and co-workers demonstrated that ATX was the same protein as a known lysophopholipase D enzyme, which catalyzed the conversion of LPC to LPA.11 Autotaxin is a multidomain protein with two Nterminal somatomedin B-like domains, a centrally located phosphodiesterase domain, and a catalytically inactive nuclease-like domain on the C-terminal region. It is expressed in four main isoforms (ATXα−δ) with largely unknown differential functionality in vivo.7 The catalytic domain of ATX comprises two zinc ions coordinated with histidine and aspartic acid residues with a threonine alcohol serving as the nucleophile. A large hydro...

Amino acids 5 and 7, two potent and selective competitive GluR5 KA receptor antagonists, exhibited high GluR5 receptor affinity over other glutamate receptors. Their ester prodrugs 6 and 8 were orally active in three models of pain: reversal of formalin-induced paw licking, carrageenan-induced thermal hyperalgesia, and capsaicin-induced mechanical hyperalgesia.

We report the synthesis and characterization of novel 3-aryl indoles as potent and efficacious progesterone receptor (PR) antagonists with potential for the treatment of uterine fibroids. These compounds demonstrated excellent selectivity over other steroid nuclear hormone receptors such as the mineralocorticoid receptor (MR). They were prepared from 2-bromo-6-nitro indole in four to six steps using a Suzuki cross-coupling as the key step. Compound 8f was orally active in the complement 3 model of progesterone antagonism in the rat uterus and demonstrated partial antagonism in the McPhail model of progesterone activity.KEYWORDS Progesterone, progesterone receptor, NR3C3, progesterone receptor antagonist, uterine fibroids, Suzuki cross-coupling reaction U terine fibroids (leiomyomas) are benign tumors that develop from smooth muscle cells and fibrous connective tissues of the uterus. 1-3 Although most are asymptomatic, in some women fibroids cause abnormal menstrual bleeding, pelvic pain, and reproductive dysfunction. 4 The incidence of fibroids increases with age during the reproductive years and peaks between 35 and 40 years old. 5 For those women whose quality of life is negatively impacted, hysterectomy is often necessary. As a result, fibroids are the primary indication for over 200,000 hysterectomies in the U.S. per year. 6,7 An evaluation of hysterectomy cases revealed a similar incidence (77%) in both post-and premenopausal women. 8 The fertility of premenopausal women can be decreased by the presence of submucosal myomas, which are fibroids partially in the cavity and partially in the wall of the uterus. 9 Since hysterectomy is unacceptable for a woman who desires a future pregnancy, surgical procedures have been developed that preserve the uterus, such as myomectomy (fibroid removal with uterine retention), laser ablation, or embolization. Removal of fibroid growths can restore fertility. 9 However, these treatments are invasive, expensive, and associated with a high rate of fibroid recurrence. 10 Therefore, there is an unmet medical need for a noninvasive, pharmaceutical treatment of uterine fibroids in both post-and premenopausal women.Currently the only pharmaceutical treatment for uterine fibroids involves the use of gonadotropin-releasing hormone (GnRH) agonists such as Lupron. These peptide hormones act on the pituitary gland, resulting in a down-regulation of the hypothalamic-pituitary-ovarian (HPO) axis, which decreases the release of gonadotropins (FSH and LH) and subsequently reduces the production of the ovarian hormones estrogen and progesterone. Withdrawal of ovarian hormone stimulation reduces uterine volume and fibroid size. 11 Unfortunately, this benefit is accompanied by side effects, most notably bone loss, which limits treatment duration. Once therapy is discontinued, fibroids usually return. As a result, GnRH agonists are primarily used to reduce fibroid size prior to surgical removal.Clinically, fibroids enlarge in women treated with norethynodrel, a steroidal progesterone ...

A series of 6-substituted decahydroisoquinoline-3-carboxylic acids were prepared as excitatory amino acid (EAA) receptor antagonists. These compounds are antagonists at the N-methyl-D-aspartate (NMDA) and 2-amino-3-(5-methyl-3-hydroxyisoxazol-4-yl) propanoic acid (AMPA) subclasses of ligand gated ion channel (ionotropic) EAA receptors. (3S,4aR, 6R,8aR)-6-(2-(1H-tetrazol-5-yl)ethyl)- 1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylic acid (9) is a potent, selective and systemically active AMPA antagonist. Other analogs from this series, including (3S,4aR,6S,8aR)-6-((1H-tetrazol-5-yl)methyl)- 1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-carboxylic acid (32) and (3S,4aR,6S,8aR)-6- (phosphonomethyl)-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline-3-ca rboxylic acid (61) are potent, selective, and systemically active NMDA antagonists. This and the subsequent publication look at the AMPA antagonist aspects of this SAR. Herein we report the effects of varying stereochemistry around the hydroisoquinoline ring; of tetrahydro-versus decahydroisoquinoline; of having the carboxylic acid at C-1 versus C-3; of varying the length of the carbon chain connecting a tetrazole to the bicyclic nucleus; and of holding the connecting chain constant at two atoms, the effect of heteroatom substitution in the position adjacent to the bicyclic nucleus and substitution with methyl or phenyl on the chain. Compounds were evaluated on rat cortical tissue for their ability to inhibit the binding of radioligands selective for AMPA ([3H]AMPA), NMDA ([3H]CGS 19755), and kainic acid ([3H]-kainic acid) receptors and for their ability to inhibit depolarizations induced by AMPA (40 microM), NMDA (40 microM), and kainic acid (10 microM). Our findings revealed that the optimal stereochemical array was the same for both NMDA (32 and 61) and AMPA (9) antagonists identified in this series and that the tetrahydroisoquinoline (25) and the C-1 carboxy (30) analogs of 9 are inactive. With a tetrazole in the distal acid position, an ethylene spacer (9) is optimal; substitution with oxygen or nitrogen on the chain in the position adjacent to the bicyclic nucleus significantly reduced activity, while substitution with a methyl or phenyl group on the chain was well tolerated.

We have explored the excitatory amino acid antagonist activity in a series of decahydroiso-quinoline-3-carboxyic acids, and within this series found the potent and selective AMPA antagonist (3SR,4aRS,6RS,8aRS)-6-(2-(1H-tetrazol-5-yl )ethyl) decahydroisoquinoline-3-carboxylic acid (1). In this and the preceding paper, we looked at the structure-activity relationships for AMPA antagonist activity in this series of compounds. We have already shown that 1 had the optimal stereochemical array and that AMPA antagonist activity was maximized for a two-carbon spacer separating a tetrazole from the bicyclic nucleus. In this paper, we explored the effects of varying the distal acid and the absolute stereochemical preferences of many of these analogs. We looked at a variety of different acid bioisosteres, including 5-membered hetereocyclic acids such as tetrazole, 1,2,4-triazole, and 3-isoxazolone; carboxylic,phosphonic, and sulfonic acid; and acyl sulfonamides. Compounds were evaluated in rat cortical tissue for their ability to inhibit the binding of radioligands selective for AMPA ([3H]AMPA), NMDA ([3H]CGS 19755), and kainic acid ([3H]kainic acid) receptors and for their ability to inhibit depolarizations induced by AMPA (40 microM), NMDA (40 microM), and kainic acid (10 microM). A number of compounds from this and the preceding paper were also evaluated in mice for their ability to block maximal electroshock-induced convulsions and ATPA-induced rigidity in mice.

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