Synthesis and structure-activity relationships of amide derivatives of (4,4-difluoro-1,2,3,4-tetrahydro-5H-1-benzazepin-5-ylidene)acetic acid as selective arginine vasopressin V2 receptor agonists

Vasopressin and Its Analogues: From Natural Hormones to Multitasking Peptides

Human neurohormone vasopressin (AVP) is synthesized in overlapping regions in the hypothalamus. It is mainly known for its vasoconstricting abilities, and it is responsible for the regulation of plasma osmolality by maintaining fluid homeostasis. Over years, many attempts have been made to modify this hormone and find AVP analogues with different pharmacological profiles that could overcome its limitations. Non-peptide AVP analogues with low molecular weight presented good affinity to AVP receptors. Natural peptide counterparts, found in animals, are successfully applied as therapeutics; for instance, lypressin used in treatment of diabetes insipidus. Synthetic peptide analogues compensate for the shortcomings of AVP. Desmopressin is more resistant to proteolysis and presents mainly antidiuretic effects, while terlipressin is a long-acting AVP analogue and a drug recommended in the treatment of varicose bleeding in patients with liver cirrhosis. Recently published results on diverse applications of AVP analogues in medicinal practice, including potential lypressin, terlipressin and ornipressin in the treatment of SARS-CoV-2, are discussed.

Synthesis and Evaluation of 3-Substituted-4-(quinoxalin-6-yl) Pyrazoles as TGF-β Type I Receptor Kinase Inhibitors

The transforming growth factor-β (TGF-β), in which overexpression has been associated with various diseases, has become an attractive molecular target for the treatment of cancers. Thirty-two quinoxaline-derivatives of 3-substituted-4-(quinoxalin-6-yl) pyrazoles 14a–d, 15a–d, 16a–d, 17a–d, 18a–d, 19a–d, 25a, 25b, 25d, 26a, 26b, 26d, 27b, and 27d were synthesized and evaluated for their activin TGF-β type I receptor kinase and p38α mitogen activated protein (MAP) kinase inhibitory activity in enzymatic assays. Among these compounds, the most active compound 19b inhibited TGF-β type I receptor kinase phosphorylation with an IC₅₀ value of 0.28 µM, with 98% inhibition at 10 µM. Compound 19b also had good selectivity index of >35 against p38α MAP kinase, with 9.0-fold more selective than clinical candidate, compound 3 (LY-2157299). A molecular docking study was performed to identify the mechanism of action of the synthesized compounds and their good binding interactions were observed. ADMET prediction of good active compounds showed that these ones possess good pharmacokinetics and drug-likeness behavior.

Crystal structures of 4-chloro-pyridine-2-carbo-nitrile and 6-chloro-pyridine-2-carbo-nitrile exhibit different inter-molecular π-stacking, C-H⋯Nnitrile and C-H⋯Npyridine inter-actions

The two title compounds are isomers of C6H3ClN2 containing a pyridine ring, a nitrile group, and a chloro substituent. The mol-ecules of each compound pack together in the solid state with offset face-to-face π-stacking, and inter-molecular C-H⋯Nnitrile and C-H⋯Npyridine inter-actions. 4-Chloro-pyridine-2-carbo-nitrile, (I), exhibits pairwise centrosymmetric head-to-head C-H⋯Nnitrile and C-H⋯Npyridine inter-actions, forming one-dimensional chains, which are π-stacked in an offset face-to-face fashion. The inter-molecular packing of the isomeric 6-chloro-pyridine-2-carbo-nitrile, (II), which differs only in the position of the chloro substituent on the pyridine ring, exhibits head-to-tail C-H⋯Nnitrile and C-H⋯Npyridine inter-actions, forming two-dimensional sheets which are π-stacked in an offset face-to-face fashion. In contrast to (I), the offset face-to-face π-stacking in (II) is formed between mol-ecules with alternating orientations of the chloro and nitrile substituents.

Diarylureas as allosteric modulators of the cannabinoid CB1 receptor: structure-activity relationship studies on 1-(4-chlorophenyl)-3-{3-[6-(pyrrolidin-1-yl)pyridin-2-yl]phenyl}urea (PSNCBAM-1)

The recent discovery of allosteric modulators of the CB1 receptor including PSNCBAM-1 (4) has generated significant interest in CB1 receptor allosteric modulation. Here in the first SAR study on 4, we have designed and synthesized a series of analogs focusing on modifications at two positions. Pharmacological evaluation in calcium mobilization and binding assays revealed the importance of alkyl substitution at the 2-aminopyridine moiety and electron deficient aromatic groups at the 4-chlorophenyl position for activity at the CB1 receptor, resulting in several analogs with comparable potency to 4. These compounds increased the specific binding of [(3)H]CP55,940, in agreement with previous reports. Importantly, 4 and two analogs dose-dependently reduced the Emax of the agonist curve in the CB1 calcium mobilization assays, confirming their negative allosteric modulator characteristics. Given the side effects associated with CB1 receptor orthosteric antagonists, negative allosteric modulators provide an alternative approach to modulate the pharmacologically important CB1 receptor.

Trainable structure-activity relationship model for virtual screening of CYP3A4 inhibition

A new structure-activity relationship model predicting the probability for a compound to inhibit human cytochrome P450 3A4 has been developed using data for >800 compounds from various literature sources and tested on PubChem screening data. Novel GALAS (Global, Adjusted Locally According to Similarity) modeling methodology has been used, which is a combination of baseline global QSAR model and local similarity based corrections. GALAS modeling method allows forecasting the reliability of prediction thus defining the model applicability domain. For compounds within this domain the statistical results of the final model approach the data consistency between experimental data from literature and PubChem datasets with the overall accuracy of 89%. However, the original model is applicable only for less than a half of PubChem database. Since the similarity correction procedure of GALAS modeling method allows straightforward model training, the possibility to expand the applicability domain has been investigated. Experimental data from PubChem dataset served as an example of in-house high-throughput screening data. The model successfully adapted itself to both data classified using the same and different IC₅₀ threshold compared with the training set. In addition, adjustment of the CYP3A4 inhibition model to compounds with a novel chemical scaffold has been demonstrated. The reported GALAS model is proposed as a useful tool for virtual screening of compounds for possible drug-drug interactions even prior to the actual synthesis.