Synthesis of substituted pyrimidines as corticotropin releasing factor (CRF) receptor ligands

Design, Synthesis, and Biological Evaluations of Novel Thiazolo[4,5-d]pyrimidine Corticotropin Releasing Factor (CRF) Receptor Antagonists as Potential Treatments for Stress Related Disorders and Congenital Adrenal Hyperplasia (CAH)

Corticotropin-releasing factor (CRF) is a key neuropeptide hormone that is secreted from the hypothalamus. It is the master hormone of the HPA axis, which orchestrates the physiological and behavioral responses to stress. Many disorders, including anxiety, depression, addiction relapse, and others, are related to over-activation of this system. Thus, new molecules that may interfere with CRF receptor binding may be of value to treat neuropsychiatric stress-related disorders. Also, CRF1R antagonists have recently emerged as potential treatment options for congenital adrenal hyperplasia. Previously, several series of CRF1 receptor antagonists were developed by our group. In continuation of our efforts in this direction, herein we report the synthesis and biological evaluation of a new series of CRF1R antagonists. Representative compounds were evaluated for their binding affinities compared to antalarmin. Four compounds (2, 5, 20, and 21) showed log IC50 values of -8.22, -7.95, -8.04, and -7.88, respectively, compared to -7.78 for antalarmin. This result indicates that these four compounds are superior to antalarmin by 2.5, 1.4, 1.7, and 1.25 times, respectively. It is worth mentioning that compound 2, in terms of IC50, is among the best CRF1R antagonists ever developed in the last 40 years. The in silico physicochemical properties of the lead compounds showed good drug-like properties. Thus, further research in this direction may lead to better and safer CRF receptor antagonists that may have clinical applications, particularly for stress-related disorders and the treatment of congenital adrenal hyperplasia.

Antiproliferative Activity of (-)-Isopulegol-based 1,3-Oxazine, 1,3-Thiazine and 2,4-Diaminopyrimidine Derivatives

A series of novel heterocyclic structures, namely 1,3-oxazines, 1,3-thiazines and 2,4-diaminopyrimidines, were designed and synthesised. The bioassay tests demonstrated that, among these analogues, 2,4-diaminopyridine derivatives showed significant antiproliferative activity against different human cancer cell lines (A2780, SiHa, HeLa, MCF-7 and MDA-MB-231). Pyrimidines substituted with N2 -(p-trifluoromethyl)aniline, in particular, displayed a potent inhibitory effect on the growth of cancer cells. Structure-activity relationships were also studied from the aspects of stereochemistry on the aminodiol moiety as well as exploring the effects of substituents on the pyrimidine scaffold.

Thiazolopyrimidine Scaffold as a Promising Nucleus for Developing Anticancer Drugs: a Review in Last Decade

The thiazolopyrimidine nucleus is a bioisostericanalog of purine and an important class of N-containing heterocycles. Thiazolopyrimidine scaffolds are considered a promising class of bioactive compounds that encompass diverse biological activities such as antibacterial, antiviral, antifungal, anticancer, corticotrophin-releasing factor antagonists, anti-inflammatory, antituberculosis, and glutamic receptors antagonists. Despite the importance of thiazolopyrimidines from a pharmacological viewpoint, there is hardly a comprehensive review on this important heterocyclic nucleus. Throughout the years, those scaffolds have been studied extensively for its anticancer properties and several compounds were designed, synthesized, and evaluated for their anticancer effects with activity in the µM to nM range. However, there are hardly any reviews covering the anticancer effects of thiazolopyrimidines. In this review, an effort was made to compile literatures covering the anticancer activity of thiazolopyrimidines reported in the last decade (2010-2020). Nearly thirty articles were reviewed and compounds which IC50 < 50 µM against at least 50% of the used cell lines were listed in this review. The best ten compounds (10a, 14b, 17g, 18,25e, 25k, 34e, 41i, 49a, & 49c) show the best anticancer activity against the corresponding cell lines during the last 10 years are highlighted. By highlighting the most active compounds, this review article sheds light on the structural features associated with the strongest anticancer effects to provide guidance to future research aiming to develop anticancer molecules.

Design, synthesis, structural optimization, SAR, in silico prediction of physicochemical properties and pharmacological evaluation of novel & potent thiazolo[4,5-d]pyrimidine corticotropin releasing factor (CRF) receptor antagonists

Corticotropin-releasing factor (CRF) is a 41-amino-acid neuropeptide secreted from the hypothalamus and is the main regulator of the hypothalamus-pituitary-adrenocortical (HPA) axis. CRF is the master hormone which modulates physiological and behavioral responses to stress. Many disorders including anxiety, depression, addictive disorders and others are related to over activation of the CRF system. This suggests that new molecules which can interfere with CRF binding to its receptors may be potential candidates for neuropsychiatric drugs to treat stress-related disorders. Previously, three series of pyrimidine and fused pyrimidine CRF₁ receptor antagonists were synthesized by our group and specific binding assays, competitive binding studies and determination of the ability to antagonize the agonist-stimulated accumulation of cAMP (the second messenger for CRF receptors) were reported. In continuation of our efforts in this direction, in the current manuscript, we report the synthesis & biological evaluation of a new series of CRF₁ receptor antagonists. Seven compounds showed promising binding affinity with the best two compounds (compounds 6 & 43) displaying a superior binding affinity to all of our previous compounds. Compounds 6 & 43 have only 4 times and 2 times less binding affinity than the standard CRF antagonist antalarmin, respectively. Thus, our two best lead compounds (compound 6 & 43) can be considered potent CRF receptor antagonists with binding affinity of 41.0 & 19.2 nM versus 9.7 nM for antalarmin.

Synthesis, in vitro biological investigation, and molecular dynamics simulations of thiazolopyrimidine based compounds as corticotrophin releasing factor receptor-1 antagonists

Corticotrophin releasing factor receptor-1 (CRFR1) is a potential target for treatment of depression and anxiety through modifying stress response. A series of new thiazolo[4,5-d]pyrimidine derivatives were designed, prepared and biologically evaluated as potential CRFR1 antagonists. Four compounds produced more than fifty percent inhibition in the [125I]-Tyr0-sauvagine specific binding assay. Assessment of binding affinities revealed that compound (3-(2,4-dimethoxyphenyl)-7-(dipropylamino)-5-methylthiazolo[4,5-d]pyrimidin-2(3H)-one) 8c was the best candidate with highest binding affinity (Ki = 32.1 nM). Further evaluation showed the ability of compound 8c to inhibit CRF induced cAMP accumulation in a dose response manner. Docking and molecular dynamics simulations were used to investigate potential binding modes of synthesized compounds as well as the stability of 8c-CRFR1 complex. These studies suggest similar allosteric binding of 8c compared to that of the co-crystalized ligand CP-376395 in 4K5Y pdb file.

Selective antagonism of CRF1 receptor by a substituted pyrimidine

The corticotrophin-releasing factor (CRF) and its type 1 receptor (CRF₁R) regulate the hypothalamic-pituitary-adrenal axis, as well as other systems, thus playing a crucial role in the maintenance of homeostasis. Non-peptide CRF₁R-selective antagonists exert therapeutic effects on experimental animals with abnormal regulation of their homeostatic mechanisms. However, none of them is as yet in clinical use. In an effort to develop novel small non-peptide CRF₁R-selective antagonists, we have synthesized a series of substituted pyrimidines described in a previous study. These small molecules bind to CRF₁R, with analog 3 having the highest affinity. Characteristic structural features of analog 3 are a N,N-bis(methoxyethyl)amino group at position 6 and a methyl in the alkythiol group at position 5. Based on the binding profile of analog 3, we selected it in the present study for further pharmacological characterization. The results of this study suggest that analog 3 is a potent CRF₁R-selective antagonist, blocking the ability of sauvagine, a CRF-related peptide, to stimulate cAMP accumulation in HEK 293 cells via activation of CRF₁R, but not via CRF₂R. Moreover, analog 3 blocked sauvagine to stimulate the proliferation of macrophages, further supporting its antagonistic properties. We have also constructed molecular models of CRF₁R to examine the interactions of this receptor with analog 3 and antalarmin, a prototype CRF₁R-selective non-peptide antagonist, which lacks the characteristic structural features of analog 3. Our data facilitate the design of novel non-peptide CRF₁R antagonists for clinical use.

Quinoxalines as potent selective CRFRs ligands for monitoring and brain diagnostic

The paper highlighted quinoxalines as potent ligands to corticotropin-releasing factor receptor types 1 and 2. The content includes design and structure-activity relationship of 50 model substances to CRFR1, CRFR2α and CRF2β, respectively. It is important to bear in mind, that our concept has based on challenging research task, designing for selective CRFRs ligands. Because,: (i) These macromolecules can bond more than one ligand, thus causing for a distinct physiological response; (ii) CRFRs also participate readily in protein-protein interactions; (iii) CRFRs have two step activation mechanism and; (iv) CRFR1 has low selectivity. In spite of, numerous research efforts, which have been devoted to the isolation of series peptidic and non-peptidic CRFRs agonists, the poor penetration across blood-brain barrier restricts, their wide application in the clinical practice. Furthermore, the biological role of CRFR2 is not yet fully understood. For that reason, the studies of the structure-activity relationship have significant impact in the field. The great advantages of quinoxalines as prospective ligands are based on their: (a) One-step synthetic road, using mild experimental conditions and, allowing to involve various functional groups in the molecular scaffold as well as good-to-excellent yields, employing Fischer and Hinsberg methods; (b) High selectivity to CRFRs sub-types and; (c) Tunable fluorescence emission within the frame of a large scale of the electromagnetic spectrum ∈ 500-700 nm.