5-Aryluracils as potent GnRH antagonists—Characterization of atropisomers

Novel non-peptide uracil-derived human gonadotropin-releasing hormone receptor antagonists

Gonadotropin-releasing hormone (GnRH) is the main regulator of the reproductive system, acting on gonadotropic cells by binding to the GnRH1 receptor (GnRH1R). Traditionally, therapies targeting this receptor have relied on peptide modulators, which required subcutaneous or intramuscular injections. Due to the limitations of the parenteral administrations, there is a growing interest in developing oral small molecule modulators of GnRH1R as more convenient therapeutic alternatives. In this study, we examined the potential of chemically modifying elagolix, the first approved non-peptide, orally active GnRH1R antagonist, to increase its atropisomeric properties by introducing new moieties. We designed and synthesized the thio-uracil (1) and cytosine (2) derivatives of elagolix, both demonstrating GnRH1R antagonistic activities, with EC50 values of 39 and 110 nM, respectively. The atropisomers of 1 and 2 were efficiently separated using silica gel chromatography, and extensive NMR investigation, supported by Density Functional Theory (DFT) calculations, allowed us to define their conformations and rotational barriers. Docking and Molecular Dynamics (MD) studies revealed that 1 and 2 bind to GnRH1R with ΔG values comparable to elagolix, but through distinct binding modes. These results highlight the potential of non-peptide modulators to effectively modulate GnRH1R activity and pave the way for developing novel modulators.

Elagolix Sodium Salt and Its Synthetic Intermediates: A Spectroscopic, Crystallographic, and Conformational Study

Elagolix sodium salt is the first marketed orally active non-peptide gonadotropin-releasing hormone receptor antagonist (GnRHR-ant) for the management of hormone dependent diseases, such as endometriosis and uterine fibroids. Despite its presence on the market since 2018, a thorough NMR analysis of this drug, together with its synthetic intermediates, is still lacking. Hence, with the aim of filling this literature gap, we here performed a detailed NMR investigation, which allowed the complete assignment of the ¹H, ¹³C, and ¹⁵N NMR signals. These data allowed, with the support of the conformational analysis, the determination of the stereochemical profile of the two atropisomers, detectable in solution. Moreover, these latter were also detected by means of cellulose-based chiral HPLC, starting from a sample prepared through an implemented synthetic procedure with respect to the reported ones. Overall, these results contribute to further understanding of the topic of atropisomerism in drug discovery and could be applied in the design of safe and stable analogs, endowed with improved target selectivity.

Atropisomerism transforming anti-cancer drug discovery

Atropisomerism is a stereochemical phenomenon that describes how groups are arranged in space as a result of their impeded rotation around a single bond. It is one of the frequently underappreciated conformational kinds of chirality. A significant role for atropisomers in drug discovery and development has been established via substantial study on the characteristics of molecules exhibiting this form of chirality. According to studies on the target selectivity of anti-cancer drugs, it was identified that atropisomers of specific compounds could be examined to modulate the selectivity of promiscuous inhibitors, which are a key target in cancer therapy. Conversely, it was discovered that these deliberate rigidifications of possible molecules along an axis of chirality gave an abundant possibility of acquiring more tailored anti-cancer action. Atropisomerism plays a significant role in altering pharmacodynamic and pharmacokinetic properties and thereby the success of any proposed drug candidate. It is thus necessary to anticipate the impact of stereogenic centres in such compounds on cancer drug development. Hence, herein we review atropisomeric anti-cancer moieties which have been investigated based on their target proteins, origin and isomerism. The insights offered herein would be extremely useful in anti-cancer drug design, pave way for new avenues to development promising potent agents to combat this life-threatening disease.

The crystal structure of 5-(2-fluoro-3-methoxyphenyl)-1-(2-fluoro-6-(trifluoromethyl)benzyl)-6-methylpyrimidine-2,4(1H,3H)-dione, C20H15F5N2O3

C20H15F5N2O3, orthorhombic, Pbca (no. 61), a = 10.9913 (4) Å, b = 11.0451(5) Å, c = 30.3925(14) Å, V = 3689.6 (3) Å3, Z = 8, R gt (F) = 0.0360, wR ref (F 2) = 0.0927, T = 170 K.

Uterine fibroids: an update on current and emerging medical treatment options

Uterine fibroids are the most common gynecological disorder, classically requiring surgery when symptomatic. Although attempts at finding a nonsurgical cure date back to centuries, it is only around the middle of the last century that serious attempts at a medical treatment were carried out. Initially, both progestins and estrogen–progestin combinations have been utilized, although proof of their usefulness is lacking. A major step forward was achieved when peptide analogs of the GnRH were introduced, first those with superagonist properties and subsequently those acting as antagonists. Initially, the latter produced side effects preventing their routine utilization; eventually, this problem was overcome following the synthesis of cetrorelix. Because both types of analogs produce hypoestrogenism, their use is limited to a maximum of 6 months and, for this reason, today they are utilized as an adjuvant treatment before surgery with overall good results. Over the last decade, new, nonpeptidic, orally active GnRH-receptor blockers have also been synthesized. One of them, Elagolix, is in the early stages of testing in women with fibroids. Another fundamental development has been the utilization of the so-called selective progesterone receptor modulators, sometimes referred to as “antiprogestins”. The first such compound to be applied to the long-term treatment of fibroids was Mifepristone; today, this compound is mostly used outside of Western Countries, where the substance of choice is Ulipristal acetate. Large clinical trials have proven the effectiveness of Ulipristal in the long-term medical therapy of fibroids, although some caution must be exercised because of the rare occurrence of liver complications. All selective progesterone receptor modulators produce unique endometrial changes that are today considered benign, reversible, and without negative consequences. In conclusion, long-term medical treatment of fibroids seems possible today, especially in premenopausal women.

Discovery of 1-{4-[1-(2,6-difluorobenzyl)-5-[(dimethylamino)methyl]-3-(6-methoxypyridazin-3-yl)-2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-6-yl]phenyl}-3-methoxyurea (TAK-385) as a potent, orally active, non-peptide antagonist of the human gonadotropin-releasing hormone receptor

We previously discovered an orally active human gonadotropin-releasing hormone (GnRH) receptor antagonist, thieno[2,3-d]pyrimidine-2,4-dione derivative 1 (sufugolix). To reduce the cytochrome P450 (CYP) inhibitory activity and improve in vivo GnRH antagonistic activity, further optimization of this scaffold was carried out. We focused our synthetic efforts on chemical modification at the 5 and 3 positions of the thieno[2,3-d]pyrimidine-2,4-dione ring based on computational modeling, which resulted in the discovery of 1-{4-[1-(2,6-difluorobenzyl)-5-[(dimethylamino)methyl]-3-(6-methoxypyridazin-3-yl)-2,4-dioxo-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidin-6-yl]phenyl}-3-methoxyurea (16b) as a highly potent and orally active GnRH antagonist. Compound 16b showed potent in vitro GnRH antagonistic activity in the presence of fetal bovine serum (FBS) without CYP inhibition. Oral administration of 16b maintained the suppressive effect of the plasma luteinizing hormone levels in castrated cynomolgus monkeys at a 3 mg/kg dose for more than 24 h. Compound 16b is currently under clinical development with the code name of TAK-385.