Projected Dose Optimization of Amino- and Hydroxypyrrolidine Purine PI3Kδ Immunomodulators

Optimization of virtual screening against phosphoinositide 3-kinase delta: Integration of common feature pharmacophore and multicomplex-based molecular docking

Extensive research has accumulated which suggests that phosphatidylinositol 3-kinase delta (PI3Kδ) is closely related to the occurrence and development of various human diseases, making PI3Kδ a highly promising drug target. However, PI3Kδ exhibits high homology with other members of the PI3K family, which poses significant challenges to the development of PI3Kδ inhibitors. Therefore, in the present study, a hybrid virtual screening (VS) approach based on a ligand-based pharmacophore model and multicomplex-based molecular docking was developed to find novel PI3Kδ inhibitors. 13 crystal structures of the human PI3Kδ-inhibitor complex were collected to establish models. The inhibitors were extracted from the crystal structures to generate the common feature pharmacophore. The crystallographic protein structures were used to construct a naïve Bayesian classification model that integrates molecular docking based on multiple PI3Kδ conformations. Subsequently, three VS protocols involving sequential or parallel molecular docking and pharmacophore approaches were employed. External predictions demonstrated that the protocol combining molecular docking and pharmacophore resulted in a significant improvement in the enrichment of active PI3Kδ inhibitors. Finally, the optimal VS method was utilized for virtual screening against a large chemical database, and some potential hit compounds were identified. We hope that the developed VS strategy will provide valuable guidance for the discovery of novel PI3Kδ inhibitors.

Copper Catalyzed Three-Component Ullmann C-S Coupling in PEG for the Synthesis of 6-Aryl/alkylthio-purines

To tackle the environmental unfriendly issue in existing synthesis strategies for 6-substitued thiopurine derivatives, such as poor step economy, frequent use of malodorous organic sulfur starting materials, toxic organic solvents, and equivalent dosage of base, we have developed a CuI-catalyzed base-free three-component Ullmann C-S coupling synthetic strategy, featured using inorganic salt Na2S as the sulfur source and nontoxic PEG-600 as the solvent. The newly developed strategy is particularly effective for the synthesis of 6-arylthiopurines. The high catalytic efficiency in PEG-600 can be rationalized by the high soluble ability of CuI catalyst, likely due to the presence of multiple oxygen coordination sites in PEG.

Discovery of Highly Selective and Orally Bioavailable PI3Kδ Inhibitors with Anti-Inflammatory Activity for Treatment of Acute Lung Injury

PI3Kδ is a promising target for the treatment of inflammatory disease; however, the application of PI3Kδ inhibitors in acute respiratory inflammatory diseases is rarely investigated. In this study, through scaffold hopping design, we report a new series of 1H-pyrazolo[3,4-d]pyrimidin-4-amine-tethered 3-methyl-1-aryl-1H-indazoles as highly selective and potent PI3Kδ inhibitors with significant anti-inflammatory activities for treatment of acute lung injury (ALI). There were 29 compounds designed, prepared, and subjected to PI3Kδ inhibitory activity evaluation and anti-inflammatory activity evaluation in macrophages. (S)-29 was identified as a candidate with high PI3Kδ inhibitory activity, isoform selectivity, and high oral bioavailability. The in vivo administration of (S)-29 at 10 mg/kg dosage could significantly ameliorate histopathological changes and attenuate lung inflammation in lung tissues of LPS-challenged mice. Molecular docking demonstrated the success of scaffold hopping design. Overall, (S)-29 is a potent PI3Kδ inhibitor which might be a promising candidate for the treatment of ALI.

Design, synthesis and biological evaluation of novel selective PI3Kδ inhibitors containing pyridopyrimidine scaffold

Aim: In our study compounds with pyrido[3,2-d]pyrimidine and pyrido[3,4-d]pyrimidine were designed, synthesized and evaluated for their biological activity against hematologic tumors. Methods: The biological activity of compounds was evaluated by ADP-Glo Luminescence assay, MTT [3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di- phenytetrazoliumromide] assay, western blotting and flow cytometry, respectively. Results: Compounds A1, A5 and A7 containing pyrido[3,2-d]pyrimidine inhibited phosphoinositide 3-kinase-δ (PI3Kδ) at subnanomolar levels and had good δ-isoform selectivity. A1, A5 and A7 showed significant inhibitory effects against SU-DHL-6 cells and effectively inhibited Akt phosphorylation in a good concentration-dependent manner. A7 induced apoptosis and caused cell cycle arrest in SU-DHL-6 cells. Docking studies showed that A1, A5 and A7 bound tightly to PI3Kδ through key hydrogen bonding interactions. Conclusion: This study suggests that employing pyrido[3,2-d]pyrimidine can facilitate the design of novel potent and selective PI3Kδ inhibitors.

Approved Small-Molecule ATP-Competitive Kinases Drugs Containing Indole/Azaindole/Oxindole Scaffolds: R&D and Binding Patterns Profiling

Kinases are among the most important families of biomolecules and play an essential role in the regulation of cell proliferation, apoptosis, metabolism, and other critical physiological processes. The dysregulation and gene mutation of kinases are linked to the occurrence and development of various human diseases, especially cancer. As a result, a growing number of small-molecule drugs based on kinase targets are being successfully developed and approved for the treatment of many diseases. The indole/azaindole/oxindole moieties are important key pharmacophores of many bioactive compounds and are generally used as excellent scaffolds for drug discovery in medicinal chemistry. To date, 30 ATP-competitive kinase inhibitors bearing the indole/azaindole/oxindole scaffold have been approved for the treatment of diseases. Herein, we summarize their research and development (R&D) process and describe their binding models to the ATP-binding sites of the target kinases. Moreover, we discuss the significant role of the indole/azaindole/oxindole skeletons in the interaction of their parent drug and target kinases, providing new medicinal chemistry inspiration and ideas for the subsequent development and optimization of kinase inhibitors.

Targeting the PI3K/AKT/mTOR Signaling Pathway in the Treatment of Human Diseases: Current Status, Trends, and Solutions

The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is one of the most important intracellular pathways involved in cell proliferation, growth, differentiation, and survival. Therefore, this route is a prospective biological target for treating various human diseases, such as tumors, neurodegenerative diseases, pulmonary fibrosis, and diabetes. An increasing number of clinical studies emphasize the necessity of developing novel molecules targeting the PI3K/AKT/mTOR pathway. This review focuses on recent advances in ATP-competitive inhibitors, allosteric inhibitors, covalent inhibitors, and proteolysis-targeting chimeras against the PI3K/AKT/mTOR pathway, and highlights possible solutions for overcoming the toxicities and acquired drug resistance of currently available drugs. We also provide recommendations for the future design and development of promising drugs targeting this pathway.