Structure-activity relationships of SERMs optimized for uterine antagonism and ovarian safety

Consensus Induced Fit Docking (cIFD): methodology, validation, and application to the discovery of novel Crm1 inhibitors

We present the Consensus Induced Fit Docking (cIFD) approach for adapting a protein binding site to accommodate multiple diverse ligands for virtual screening. This novel approach results in a single binding site structure that can bind diverse chemotypes and is thus highly useful for efficient structure-based virtual screening. We first describe the cIFD method and its validation on three targets that were previously shown to be challenging for docking programs (COX-2, estrogen receptor, and HIV reverse transcriptase). We then demonstrate the application of cIFD to the challenging discovery of irreversible Crm1 inhibitors. We report the identification of 33 novel Crm1 inhibitors, which resulted from the testing of 402 purchased compounds selected from a screening set containing 261,680 compounds. This corresponds to a hit rate of 8.2 %. The novel Crm1 inhibitors reveal diverse chemical structures, validating the utility of the cIFD method in a real-world drug discovery project. This approach offers a pragmatic way to implicitly account for protein flexibility without the additional computational costs of ensemble docking or including full protein flexibility during virtual screening.

Innovative oral treatments of uterine leiomyoma

Uterine fibroids (leiomyoma), the benign tumors of the uterine wall, are very common cause of morbidity in reproductive age women usually in the form of excessive vaginal bleeding, chronic pelvic pain, miscarriage and infertility. These tumors are the leading indication for hysterectomy in the United States. Uterine fibroids are about 4 times higher in blacks compared to whites and constitute a major health disparity challenge. The estimated cost of uterine fibroids is up to $34.4 billion annually. Additionally, women who suffer from this disease and desire to maintain their future fertility have very limited treatment choices. Currently, there is no effective long-term medicinal treatment for uterine fibroids. While surgery has traditionally been the gold standard for the treatment of uterine fibroids, there is growing interest towards orally administered medications for the management of leiomyoma-related symptoms. In this paper, we will discuss these promising innovative oral medical treatments in detail.

Parallel synthesis of a desketoraloxifene analogue library via iodocyclization/palladium-catalyzed coupling

For a future structure-activity relationship (SAR) study, a library of desketoraloxifene analogues has been prepared by parallel synthesis using iodocyclization and subsequent palladium-catalyzed coupling reactions. Points of desketoraloxifene diversification involve the two phenolic hydroxyl groups and the aliphatic amine side chain. This approach affords oxygen-bearing 3-iodobenzo[b]thiophenes 4 in excellent yields, which are easily further elaborated using a two-step approach involving Suzuki-Miyaura and Mitsunobu coupling reactions to give multimethoxy-substituted desketoraloxifene analogues 6. Various hydroxyl-substituted desketoraloxifene analogues 7 were subsequently generated by demethylation with BBr(3).

Novel 3-aryl indoles as progesterone receptor antagonists for uterine fibroids

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.

Identification and structure-activity relationships of chromene-derived selective estrogen receptor modulators for treatment of postmenopausal symptoms

As part of a program aimed at the development of selective estrogen receptor modulators (SERMs), novel chromene scaffolds, benzopyranobenzoxapanes, were discovered. Many compounds showed binding affinity as low as 1.6-200 nM, displayed antagonist behaviors in the MCF-7 human breast adenocarcinoma cell line as well in Ishikawa cell line with IC(50) values in the range 0.2-360 nM. On the basis of the side chain substitution, various compounds demonstrated strong inhibitory activity in anti-uterotropic assay. Compound 7-(R) and its major metabolites 5-(R) and 6-(R) were evaluated in several in vivo models of estrogen action. Relative to a full estrogen agonist (ethynyl estradiol) and the SERM raloxifene, 7-(R) was found to be a potent SERM that behaved as antagonist in the uterus and exhibited estrogen agonistic activity on bone, plasma lipids, hot flush, and vagina. The overall pharmacokinetic profile and stability were significantly improved compared to those of the phase 2 development compound 9-(R).

Development of an early biomarker for the ovarian liability of selective estrogen receptor modulators in rats

Selective estrogen receptor modulators (SERMs) have the potential to treat estrogen sensitive diseases such as uterine leiomyoma and endometriosis, which are prevalent in reproductive age women. However, SERMs also increase the risk of developing ovarian cysts in this population, a phenomenon that is not seen in postmenopausal women. It is believed that current SERMs partially block estradiol's ability to downregulate gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus thereby interfering with estradiol's negative feedback, leading to increased ovarian stimulation by gonadotropins, and cyst formation. It has been postulated that a SERM with poor brain exposure would have less negative effect on the HPO axis, therefore reducing the risk of developing ovarian cysts. In order to test this hypothesis, we identified an early marker of SERM-dependent ovarian effects: upregulation of Cyp17a1 mRNA. SERMs known to cause ovarian cysts upregulate Cyp17a1 after only 4 days of dosing and suppression of the HPO axis prevented this regulation, indicating that ovarian expression of Cyp17a1 was secondary to SERM's effect on the brain. We then characterized three SERMs with similar binding affinity and antagonist effects on the uterus for their relative brain/plasma exposure and ovarian effects. We found that the degree of brain exposure correlated very well with Cyp17a1 expression.

The selective oestrogen receptor modulator, LY362321, is not neuroprotective in a rat model of transient focal ischaemia

Selective oestrogen receptor modulators (SERMs) may offer improved alternatives to oestrogen as neuroprotectants in experimental stroke. The present study investigated the role of a novel SERM, LY362321, in a rat model of transient middle cerebral artery occlusion (MCAO). Female Sprague-Dawley rats were ovariectomised and began receiving daily s.c. injections of either 1 mg/kg (n = 13), 10 mg/kg (n = 14) of LY362321, or vehicle (n = 13). The left MCA was temporarily occluded (90 min), with cortical blood flow monitoring, at 12 days post ovariectomy. Sensorimotor function was assessed using a neurological score prior to the MCAO and daily for 3 days following the MCAO. Tissue was processed for infarct volume assessment using 2,3,5-triphenyltetra-zolium chloride staining. The results indicated that there were no significant differences amongst groups in cortical blood flow during the MCAO. Furthermore, there was no significant difference in infarct size amongst vehicle, 1, and 10 mg/kg treated animals: 22.9 +/- 5.0, 16.7 +/- 4.2, and 21.1 +/- 4.1, respectively, one-way anova [F(2,32) = 0.542, P = 0.587]. The MCAO induced a significant decline in neurological score in the vehicle group (from 14 to 7 at 24 h post-MCAO) but this was not significantly affected by LY362321 at either dose. In conclusion, pretreatment with a low or high dose of the novel SERM LY362321 did not significantly influence cerebral blood flow, infarct volume, or sensorimotor function in rats exposed to transient MCAO.