Discovery and Pharmacological Characterization of Novel Quinazoline-Based PI3K Delta-Selective Inhibitors

A comprehensive review of small molecule drugs approved by the FDA in 2023: Advances and prospects

In 2023, the U.S. Food and Drug Administration has approved 55 novel medications, consisting of 17 biologics license applications and 38 new molecular entities. Although the biologics license applications including antibody and enzyme replacement therapy set a historical record, the new molecular entities comprising small molecule drugs, diagnostic agent, RNA interference therapy and biomacromolecular peptide still account for over 50 % of the newly approved medications. The novel and privileged scaffolds derived from drugs, active molecules and natural products are consistently associated with the discovery of new mechanisms, the expansion of clinical indications and the reduction of side effects. Moreover, the structural modifications based on the promising scaffolds can provide the clinical candidates with the improved biological activities, bypass the patent protection and greatly shorten the period of new drug discovery. Therefore, conducting an appraisal of drug approval experience and related information will expedite the identification of more potent drug molecules. In this review, we comprehensively summarized the pertinent information encompassing the clinical application, mechanism, elegant design and development processes of 28 small molecule drugs, and expected to provide the promising structural basis and design inspiration for pharmaceutical chemists.

The role of the methoxy group in approved drugs

The methoxy substituent is prevalent in natural products and, consequently, is present in many natural product-derived drugs. It has also been installed in modern drug molecules with no remnant of natural product features because medicinal chemists have been taking advantage of the benefits that this small functional group can bestow on ligand-target binding, physicochemical properties, and ADME parameters. Herein, over 230 methoxy-containing small-molecule drugs, as well as several fluoromethoxy-containing drugs, are presented from the vantage point of the methoxy group. Biochemical mechanisms of action, medicinal chemistry SAR studies, and numerous X-ray cocrystal structures are analyzed to identify the precise role of the methoxy group for many of the drugs and drug classes. Although the methoxy substituent can be considered as the hybridization of a hydroxy and a methyl group, the combination of these functionalities often results in unique effects that can amount to more than the sum of the individual parts.

An integrated network pharmacology, molecular docking and experiment validation study to investigate the potential mechanism of Isobavachalcone in the treatment of osteoarthritis

BACKGROUND

In many different plants, including Dorstenia and Psoralea corylifolia L., Isobavachalcone (IBC) is a naturally occurring flavonoid chemical having a range of biological actions, including anti-inflammatory, immunomodulatory, and anti-bacterial. The "Theory of Medicinal Properties" of the Tang Dynasty states that Psoralea corylifolia L. has the ability to alleviate discomfort in the knees and waist. One of the most widespread chronic illnesses, osteoarthritis (OA), is characterized by stiffness and discomfort in the joints. However, there hasn't been much research done on the effectiveness and underlying processes of IBC in the treatment of osteoarthritis.

AIM OF THE STUDY

To investigate the potential efficacy and mechanism of IBC in treating osteoarthritis, we adopted an integrated strategy of network pharmacology, molecular docking and experiment assessment.

MATERIALS AND METHODS

The purpose of this research was to determine the impact of IBC on OA and the underlying mechanisms. IBC and OA possible targets and processes were predicted using network pharmacology, including the relationship between IBC and OA intersection targets, Cytoscape protein-protein interaction (PPI) to obtain key potential targets, and GO and KEGG pathway enrichment analysis to reveal the probable mechanism of IBC on OA. Following that, in vitro tests were carried out to confirm the expected underlying processes. Finally, in vivo tests clarified IBC's therapeutic efficacy on OA.

RESULTS

We anticipated and validated that the impact of IBC on osteoarthritis is mostly controlled by the PI3K-AKT-NF-κB signaling pathway by combining the findings of network pharmacology analysis, molecular docking and Experiment Validation.

CONCLUSIONS

This study reveals the IBC has potential to delay OA development.

Leniolisib: a novel treatment for activated phosphoinositide-3 kinase delta syndrome

IC50 = 11 nM (PI3Kδ); 244 nM (PI3Kα); 424 nM (PI3Kβ), 2,230 nM (PI3Kγ).

Cucurbitacin E reduces IL-1β-induced inflammation and cartilage degeneration by inhibiting the PI3K/Akt pathway in osteoarthritic chondrocytes

BACKGROUND

Osteoarthritis is a degenerative joint disease. Cartilage degeneration is the earliest and most important pathological change in osteoarthritis, and persistent inflammation is one of the driving factors of cartilage degeneration. Cucurbitacin E, an isolated compound in the Cucurbitacin family, has been shown to have anti-inflammatory effects, but its role and mechanism in osteoarthritic chondrocytes are unclear.

METHODS

For in vitro experiments, human chondrocytes were stimulated with IL-1β, and the expression of inflammatory genes was measured by Western blotting and qPCR. The expression of extracellular matrix proteins was evaluated by immunofluorescence staining, Western blotting and saffron staining. Differences in gene expression between cartilage from osteoarthritis patients and normal cartilage were analysed by bioinformatics methods, and the relationship between Cucurbitacin E and its target was analysed by a cellular thermal shift assay, molecular docking analysis and molecular dynamics simulation. For in vivo experiments, knee osteoarthritis was induced by DMM in C57BL/6 mouse knee joints, and the effect of Cucurbitacin E on knee joint degeneration was evaluated.

RESULTS

The in vitro experiments confirmed that Cucurbitacin E effectively inhibited the production of the inflammatory cytokine interleukin-1β(IL-1β) and cyclooxygenase-2 (COX-2) by IL-1β-stimulated chondrocytes and alleviates extracellular matrix degradation. The in vivo experiments demonstrated that Cucurbitacin E had a protective effect on the knee cartilage of C57BL/6 mice with medial meniscal instability in the osteoarthritis model. Mechanistically, bioinformatic analysis of the GSE114007 and GSE117999 datasets showed that the PI3K/AKT pathway was highly activated in osteoarthritis. Immunohistochemical analysis of PI3K/Akt signalling pathway proteins in pathological slices of human cartilage showed that the level of p-PI3K in patients with osteoarthritis was higher than that in the normal group. PI3K/Akt were upregulated in IL-1β-stimulated chondrocytes, and Cucurbitacin E intervention reversed this phenomenon. The cellular thermal shift assay, molecular docking analysis and molecular dynamics experiment showed that Cucurbitacin E had a strong binding affinity for the inhibitory target PI3K. SC79 activated Akt phosphorylation and reversed the effect of Cucurbitacin E on IL-1β-induced chondrocyte degeneration, demonstrating that Cucurbitacin E inhibits IL-1β-induced chondrocyte inflammation and degeneration by inhibiting the PI3K/AKT pathway.

CONCLUSION

Cucurbitacin E inhibits the activation of the PI3K/AKT pathway, thereby alleviating the progression of OA. In summary, we believe that Cucurbitacin E is a potential drug for the treatment of OA.

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.

New pyrimidine-N-β-D-glucosides: synthesis, biological evaluation, and molecular docking investigations

In this study, syntheses of new pyrimidine-coupled N-β-glucosides and tetra-O-acetyl derivatives were carried out. All glycoconjugates were investigated in comparison with known chemotherapeutic agents in terms of their antimicrobial and anticancer functions and DNA/protein binding affinities. Spectral data showed that all glycoside derivatives were obtained by diastereoselectivity as β-anomers. Both tested groups exhibited strong antiproliferative activity (2.29-66.84 μg/mL), but some of them had sufficiently ideal % cytotoxicity values (10.01%-16.78%). And also all synthetic compounds exhibited remarkable antibacterial activity against human pathogenic bacteria. Binding of these compounds to CT-DNA resulted in significant changes in spectral properties, consistent with groove binding. Molecular docking studies of some compounds revealed that the docking score, complex energy, and MM-GBSA ΔGBind energy values were consistent with the experimental results, which showed that the new compounds were potent chemotherapeutic agents. Overall bioactivity results suggest that these compounds may be candidates as new chemotherapeutic agents and deserve further pharmacological evaluation.

Binding and selectivity studies of phosphatidylinositol 3-kinase (PI3K) inhibitors

Overexpression of the Phosphatidylinositol 3-kinase (PI3K) proteins have been observed in cancer cells. Targeting the phosphatidylinositol 3-kinase (PI3K) signaling transduction pathway by inhibition of the PI3K substrate recognition sites has been proved to be an effective approach to block cancer progression. Many PI3K inhibitors have been developed. Seven drugs have been approved by the US FDA with a mechanism of targeting the phosphatidylinositol 3-kinase/protein kinase-B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway. In this study, we used docking tools to investigate selective binding of ligands toward four different subtypes of PI3Ks (PI3Kα, PI3Kβ, PI3Kγ and PI3Kδ). The affinity predicted from both the Glide dock and the Movable-Type (MT)-based free energy calculations agreed well with the experimental data. The validation of our predicted methods with a large dataset of 147 ligands showed very small mean errors. We identified residues that may dictate the subtype-specific binding. Particularly, residues Asp964, Ser806, Lys890 and Thr886 of PI3Kγ might be utilized for PI3Kγ-selective inhibitor design. Residues Val828, Trp760, Glu826 and Tyr813 may be important for PI3Kδ-selective inhibitor binding.

Stereoselective Synthesis of 12-Tetrazolyl Substituted (E)-5H-Quinazolino[3,2-a]quinazolines via Sequential Ugi-Azide/Staudinger/aza-Wittig/Addition/Ag(I)-Catalyzed Cyclization

A new efficient and stereoselective synthesis of 12-tetrazolyl substituted (E)-5H-quinazolino[3,2-a]quinazolines via sequential Ugi-azide/Staudinger/aza-Wittig/addition/Ag(I)-catalyzed cyclization was developed. The four-component reactions of 2-azidobenzaldehyde, 2-(alkynyl)benzenamine, isocyanide, and trimethylsilyl azide gave Ugi-azide intermediates, which were subsequently treated with triphenylphosphine and isocyanate to produce 12-tetrazolyl substituted (E)-5H-quinazolino[3,2-a]quinazolines in the presence of Ag(I) catalyst and K₂CO₃.

Discovery of 2-Methyl-2-(4-(2-methyl-8-(1H-pyrrolo[2,3-b]pyridin-6-yl)-1H-naphtho[1,2-d]imidazol-1-yl)phenyl)propanenitrile as a Novel PI3K/mTOR Inhibitor with Enhanced Antitumor Efficacy In Vitro and In Vivo

PI3K/Akt/mTOR signaling pathway is a validated drug target for cancer treatment that plays a critical role in controlling tumor growth, proliferation, and apoptosis. However, no FDA-approved PI3K/mTOR dual inhibitor exists. Thus, a candidate with a better curative effect and lower toxicity is still urgently needed. Herein, we design, synthesize, and evaluate compounds belonging to a novel series of 2-methyl-1H-imidazo[4,5-c]quinoline scaffold derivatives as PI3K/mTOR dual inhibitors. Among them, compound 8o was identified as a novel candidate with excellent kinase selectivity. It manifested remarkable antiproliferative activities against SW620 and HeLa cells. Western blot and immunohistochemical analysis results proved that 8o could regulate the PI3K/AKT/mTOR signaling pathway by inhibiting the phosphorylation of AKT and S6 proteins. Additionally, 8o presented a favorable pharmacokinetic property (oral bioavailability of 76.8%) and significant antitumor efficacy in vivo without obvious toxicity. Collectively, these results indicated that 8o is a promising agent for cancer treatment and merits further development.

Urolithin A Promotes Angiogenesis and Tissue Regeneration in a Full-Thickness Cutaneous Wound Model

The treatment of chronic wound is an important topic of current clinical issue. Neovascularization plays a crucial role in skin wound healing by delivering fresh nutrients and oxygen to the wound area. The aim of this study was to investigate the mechanisms of urolithin A (UA) in angiogenesis during wound healing. The results of in vitro experiments showed that treatment with UA (5–20 μM) promoted the proliferation, migration, and angiogenic capacity of HUVECs. Furthermore, we investigated the effect of UA in vivo using a full-thickness skin wound model. Subsequently, we found that UA promoted the regeneration of new blood vessels, which is consistent with the results of accelerated angiogenesis in vitro experiments. After UA treatment, the blood vessels in the wound are rapidly formed, and the deposition and remodeling process of the collagen matrix is also accelerated, which ultimately promotes the effective wound healing. Mechanistic studies have shown that UA promotes angiogenesis by inhibiting the PI3K/AKT pathway. Our study provides evidence that UA can promote angiogenesis and skin regeneration in chronic wounds, especially ischemic wounds.

Decursin alleviates the aggravation of osteoarthritis via inhibiting PI3K-Akt and NF-kB signal pathway

Osteoarthritis (OA) is a common joint disease that takes joint degeneration or aging as its pathological basis, and joint swelling, pain or dysfunction as its main clinical manifestations. Decursin (DE), the major active component isolated from Angelica gigas Nakai, has been demonstrated to possess anti-inflammatory effect in many diseases. But, the specific physiological mechanism of DE on OA is not clear yet. Therefore, the object of this study was to assess the therapeutic effect of DE on OA, and to explore its potential anti-inflammatory mechanisms. In vitro cell experiments, the inflammatory response in chondrocytes is mediated via interleukin-1β (IL-1β), which led to abnormal secretion of pro-inflammatory factors, such as prostaglandin E2 (PGE₂), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), cyclooxygenase-2 (COX-2), nitric oxide (NO) and inducible nitric oxide synthase (iNOS). These cytokines were all decreased by the preconditioning of DE in a dose-dependent form of 1, 5, and 10 µM. Moreover, DE could restrain IL-1β-mediated inflammatory reaction and the collapse of extracellular matrix (ECM) via reducing the secretion of ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) and MMPs (matrix metalloproteinases). In short, DE restrained IL-1β-mediated abnormal excitation of PI3K/AKT/NF-κB axis. Furthermore, molecular docking analysis showed that DE has a strong binding affinity with the inhibitory targets of PI3K. In vivo animal studies, DE treatment could helped to improve destruction of articular cartilage and decreased the serum inflammatory factor levels in an operationally induced mouse OA model. To sum up, these data obtained from the experiment indicate that DE has good prospects for the treatment of osteoarthritis.

Projected Dose Optimization of Amino- and Hydroxypyrrolidine Purine PI3Kδ Immunomodulators

The approvals of idelalisib and duvelisib have validated PI3Kδ inhibitors for the treatment for hematological malignancies driven by the PI3K/AKT pathway. Our program led to the identification of structurally distinct heterocycloalkyl purine inhibitors with excellent isoform and kinome selectivity; however, they had high projected human doses. Improved ligand contacts gave potency enhancements, while replacement of metabolic liabilities led to extended half-lives in preclinical species, affording PI3Kδ inhibitors with low once-daily predicted human doses. Treatment of C57BL/6-Foxp3-GDL reporter mice with 30 and 100 mg/kg/day of 3c (MSD-496486311) led to a 70% reduction in Foxp3-expressing regulatory T cells as observed through bioluminescence imaging with luciferin, consistent with the role of PI3K/AKT signaling in Treg cell proliferation. As a model for allergic rhinitis and asthma, treatment of ovalbumin-challenged Brown Norway rats with 0.3 to 30 mg/kg/day of 3c gave a dose-dependent reduction in pulmonary bronchoalveolar lavage inflammation eosinophil cell count.

Discovery of novel quinazoline derivatives as potent PI3Kδ inhibitors with high selectivity

Inhibition of PI3Kδ has been proved to be an efficacious strategy for the treatment of hematological malignancies where the PI3K/Akt signaling pathway is hyperactive. Herein, a series of quinazoline derivatives bearing acrylamide fragment were prepared using skeleton-deconstruction strategy. The preliminary bioactivity evaluation resulted in the discovery of lead compound 15c. Compound 15c exhibited excellent enzyme activity against PI3Kδ (IC₅₀ = 27.5 nM) compared with BEZ235 as well as the significant anti-proliferation activities. With the high selectivity over other PI3K isoforms and potent effects on PI3K/Akt pathway, 15c can be identified as a promising PI3Kδ inhibitor worthy of further profiling.

Optimization of Versatile Oxindoles as Selective PI3Kδ Inhibitors

The 3,3-disubstituted oxindole moiety is a versatile and rigid three-dimensionally shaped scaffold. When engineered with a purine hinge-binding core, exceptionally selective PI3Kδ kinase inhibitors were discovered by exploiting small differences in isoform selectivity pockets. Crystal structures of early lead 2f bound to PI3Kδ and PI3Kα helped rationalize the high selectivity observed with 2f. By attenuating the lypophilicity and metabolic liabilities of an oxindole moiety, we improved the preclinical species PK and solubility and reduced adenosine uptake activity. The excellent potency and kinome selectivity of 7-azaoxindole 4d and spirooxindole 5d, together with a low plasma clearance and good half-life in rat and dog, supported a low once-daily predicted human dose.

Research advances on selective phosphatidylinositol 3 kinase δ (PI3Kδ) inhibitors

PI3Kδ in B cells mediates antigen receptor signaling and promote neutrophil chemotaxis. The activation of PI3Kδ can cause mast cell maturation and degranulation, myeloid cell dysfunction, and cytokine release. As a key signal molecule, PI3Kδ interacts with the lipid binding domain of a variety of cellular proteins as a secondary messenger, ultimately affecting a series of significant cellular pathways in disease pathology. Therefore, many research organizations and pharmaceutical companies have studied it to develop effectively selective PI3Kδ inhibitors as therapeutics. This review summarizes research advances in varying chemical classes of selective PI3Kδ inhibitors and the structure-activity relationship, and it mainly focuses on the propeller- versus flat-type class of inhibitors.

Paeoniflorin promotes angiogenesis and tissue regeneration in a full-thickness cutaneous wound model through the PI3K/AKT pathway

The treatment of wounds remains a clinical challenge because of poor angiogenesis under the wound bed, and increasingly, the patients' need for functional and aesthetically pleasing scars. For the wound healing process, new blood vessels which can deliver nutrients and oxygen to the wound area are necessary. In this study, we investigated the pro-angiogenesis ability and mechanism in wound healing of paeoniflorin (PF), which is a traditional Chinese medicine. In our in vitro results, the ability for proliferation, migration and in vitro angiogenesis in human umbilical vein endothelial cells was promoted by coculturing with PF (1.25-5 μM). Meanwhile, molecular docking studies revealed that PF has excellent binding abilities to phosphatidylinositol-3-kinase (PI3K) and protein kinase B (AKT), and consistent with our western blot results, that PF suppressed PI3K and AKT phosphorylation. Furthermore, to investigate the healing effect of PF in vivo, we constructed a full-thickness cutaneous wound model in rats. PF stimulated the cellular proliferation status, collagen matrix deposition and remodeling processes in vitro and new blood vessel formation at the wound bed resulting in efficient wound healing after intragastric administration of 10 mg·kg^-1 ·day^-1 in vivo. Overall, PF performed the pro-angiogenetic effect in vitro and accelerating wound healing in vivo. In summary, the capacity for angiogenesis in endothelial cells could be enhanced by PF treatment via the PI3K/AKT pathway in vitro and could accelerate the wound healing process in vivo through collagen deposition and angiogenesis in regenerated tissue. This study provides evidence that application of PF represents a novel therapeutic approach for the treatment of cutaneous wounds.

Antiproliferative and Carbonic Anhydrase II Inhibitory Potential of Chemical Constituents from Lycium shawii and Aloe vera: Evidence from In Silico Target Fishing and In Vitro Testing

Lycium shawii Roem. & Schult and resin of Aloe vera (L.) BURM. F. are commonly used in Omani traditional medication against various ailments. Herein, their antiproliferative and antioxidant potential was explored. Bioassay-guided fractionation of the methanol extract of both plants led to the isolation of 14 known compounds, viz., 1-9 from L. shawii and 10-20 from A. vera. Their structures were confirmed by combined spectroscopic techniques including 1D (1H and 13C) and 2D (HMBC, HSQC, COSY) nuclear magnetic resonance (NMR), and electrospray ionization-mass spectrometry (ESI-MS). The cytotoxic potential of isolates was tested against the triple-negative breast cancer cell line (MDA-MB-231). Compound 5 exhibited excellent antiproliferative activity in a range of 31 μM, followed by compounds 1-3, 7, and 12, which depicted IC50 values in the range of 35-60 μM, while 8, 6, and 9 also demonstrated IC50 values >72 μM. Subsequently, in silico target fishing was applied to predict the most potential cellular drug targets of the active compounds, using pharmacophore modeling and inverse molecular docking approach. The extensive in silico analysis suggests that our compounds may target carbonic anhydrase II (CA-II) to exert their anticancer activities. When tested on CA-II, compounds 5 (IC50 = 14.4 µM), 12 (IC50 = 23.3), and 2 (IC50 = 24.4 µM) showed excellent biological activities in vitro. Additionally, the ethyl acetate fraction of both plants showed promising antioxidant activity. Among the isolated compounds, 4 possesses the highest antioxidant (55 μM) activity followed by 14 (241 μM). The results indicated that compound 4 can be a promising candidate for antioxidant drugs, while compound 5 is a potential candidate for anticancer drugs.

2,4-Disubstituted Quinazoline Derivatives Act as Inducers of Tubulin Polymerization: Synthesis and Cytotoxicity

BACKGROUND

During last recent years number of anti-tubulin agents were introduced for treatment of diverse kind of cancer. Despite of their potential in treatment of cancer, drug resistance and adverse toxicity such as peripheral neuropathy are some of the negative criteria of anti-tubulin agents.

METHODS

Twenty seven quinazoline derivatives were synthesized using a multicomponent reaction. The cytotoxicity of compounds 1-27 was tested in SRB assays employing five different human tumor cell lines. Effect of two of active compounds on tubulin polymerization was also checked using a commercially available assay kit. Molecular modelling studies were also performed using autodock tools software.

RESULTS

SRB assays showed that compounds 2, 9, 16 and 26, being highly cytotoxic with IC50 values ranging between 2.1 and 14.3µM. The possible mode of action of compounds, 2, 9, 16 and 26, and the taxol binding site of the protein tubulin, an important goal for antimitotic drugs, was also studied by molecular docking, which showed reasonable interactions with tubulin active site, followed by investigation of the effects of compounds 9 and 16 on the polymerization of tubulin. The results showed the tested compounds to be highly active as inducers of tubulin polymerization.

CONCLUSION

Altogether, with respect to obtained results, it is attractive and beneficial to further investigation on quinazoline scaffold as antimitotic agents.

Synthesis and biological evaluation of 4-(piperid-3-yl)amino substituted 6-pyridylquinazolines as potent PI3Kδ inhibitors

PI3Kδ is an intriguing target for developing anti-cancer agent. In this study, a new series of 4-(piperid-3-yl)amino substituted 6-pyridylquinazoline derivatives were synthesized. After biological evaluation, compounds A5 and A8 were identified as potent PI3Kδ inhibitors, with IC₅₀ values of 1.3 and 0.7 nM, respectively, which are equivalent to or better than idelalisib (IC₅₀ = 1.2 nM). Further PI3K isoforms selectivity evaluation showed that compound A5 afforded excellent PI3Kδ selectivity over PI3Kα, PI3Kβ and PI3Kγ. A8 exhibited superior PI3Kδ/γ selectivity over PI3Kα and PI3Kβ. Moreover, compounds A5 and A8 selectively exhibited anti-proliferation against SU-DHL-6 in vitro with IC₅₀ values of 0.16 and 0.12 μM. Western blot analysis indicated that A8 could attenuate the AKT^S473 phosphorylation. Molecular docking study suggested that A8 formed three key H-bonds action with PI3Kδ, which may account for its potent inhibition of PI3Kδ. These findings indicate that 4-(piperid-3-yl)amino substituted 6-pyridylquinazoline derivatives were potent PI3Kδ inhibitors with distinctive PI3K-isoforms and anti-proliferation profiles.

Preparation of isoquinazolines via metal-free [4 + 2] cycloaddition of ynamides with nitriles

TfOH-mediated [4 + 2] cycloaddition of ynamides with nitriles to construct 1,2-dihydroquinazolines is realized by a direct reaction in moderate to excellent yields (up to 93%) in a stereospecific manner. A rapid and efficient strategy has been employed for the syntheses of alkyl-substituted 1,2-dihydroquinazoline derivatives, and it exhibits good functional group tolerance, has a short reaction time, shows excellent diastereoselectivity, and is a simple and high-yielding reaction.

Optimization of 5,6,7,8-tetrahydropyrido[4,3-d]pyrimidines to generate a highly selective PI3Kδ inhibitor

Chemical optimization of the 5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine (THPP) scaffold was conducted with a focus on cellular potency while maintaining high selectivity against PI3K isoforms. Compound 11f was identified as a potent, highly selective and orally available PI3Kδ inhibitor. In addition, 11f exhibited efficacy in an in vivo antibody production model. The desirable drug-like properties and in vivo efficacy of 11f suggest its potential as a drug candidate for the treatment of autoimmune diseases and leukocyte malignancies.

Structural Determinants of Isoform Selectivity in PI3K Inhibitors

Phosphatidylinositol 3-kinases (PI3Ks) are important therapeutic targets for the treatment of cancer, thrombosis, and inflammatory and immune diseases. The four highly homologous Class I isoforms, PI3K, PI3K, PI3K and PI3K have unique, non-redundant physiological roles and as such, isoform selectivity has been a key consideration driving inhibitor design and development. In this review, we discuss the structural biology of PI3Ks and how our growing knowledge of structure has influenced the medicinal chemistry of PI3K inhibitors. We present an analysis of the available structure-selectivity-activity relationship data to highlight key insights into how the various regions of the PI3K binding site influence isoform selectivity. The picture that emerges is one that is far from simple and emphasizes the complex nature of protein-inhibitor binding, involving protein flexibility, energetics, water networks and interactions with non-conserved residues.

Identification of novel PI3Kδ inhibitors by docking, ADMET prediction and molecular dynamics simulations

BACKGROUND

Phosphoinositide-3-kinase Delta (PI3Kδ) plays a key role in B-cell signal transduction and inhibition of PI3Kδ is confirmed to have clinical benefit in certain types of activation of B-cell malignancies. Virtual screening techniques have been used to discover new molecules for developing novel PI3Kδ inhibitors with little side effects.

METHOD

Computer aided drug design method were used to rapidly screen optimal PI3Kδ inhibitors from the Asinex database. Virtual screening based molecular docking was performed to find novel and potential lead compound targeting PI3Kδ, at first. Subsequently, drug likeness studies were carried out on the retrieved hits to evaluate and analyze their drug like properties such as absorption, distribution, metabolism, excretion, and toxicity (ADMET) for toxicity prediction. Three least toxic compounds were selected for the molecular dynamics (MD) simulations for 30 ns in order to validate its stability inside the active site of PI3Kδ receptor.

RESULTS

Based on the present in silico analysis, two molecules have been identified which occupied the same binding pocket confirming the selection of active site. ASN 16296138 (Glide score: -12.175 kcal/mol, cdocker binding energy: -42.975 kcal/mol and ΔG_bind value: -90.457 kcal/mol) and BAS 00227397 (Glide score: -10.988 kcal/mol, cdocker binding energy: -39.3376 kcal/mol and ΔG_bind value: -81.953 kcal/mol) showed docking affinities comparatively much stronger than those of already reported known inhibitors against PI3Kδ. These two ligand's behaviors also showed consistency during the simulation of protein-ligand complexes for 30000 ps respectively, which is indicative of its stability in the receptor pocket.

CONCLUSION

Compound ASN 16296138 and BAS 00227397 are potential candidates for experimental validation of biological activity against PI3Kδ in future drug discovery studies. This study smoothes the path for the development of novel leads with improved binding properties, high drug likeness, and low toxicity to humans for the treatment of cancer.

Introduction of pyrrolidineoxy or piperidineamino group at the 4-position of quinazoline leading to novel quinazoline-based phosphoinositide 3-kinase delta (PI3Kδ) inhibitors

Phosphoinositide 3-kinase Delta (PI3Kδ) plays a key role in B-cell signal transduction and inhibition of PI3Kδ was confirmed to have clinical benefit in certain types of activation of B-cell malignancies. Herein, we reported a novel series of 4-pyrrolidineoxy or 4-piperidineamino substituted quinazolines, showing potent PI3Kδ inhibitory activities. Among these compounds, 12d, 14b and 14c demonstrated higher potency against PI3Kδ with the half maximal inhibitory concentration (IC50) values of 4.5, 3.0, and 3.9 nM, respectively, which were comparable to idelalisib (IC50 = 2.7 nM). The further PI3K isoforms selectivity evaluation showed that compounds 12d, 14b and 14c have excellent PI3Kδ selectivity over PI3Kα, PI3Kβ, and PI3Kγ. Moreover, compounds 12d, 14b and 14c also displayed different anti-proliferative profiles against a panel of four human B cell lines including Ramos, Raji, RPMI-8226, and SU-DHL-6. The molecular docking simulation indicated several key hydrogen bonding interactions were formed. This study suggests the introduction of pyrrolidineoxy or piperidineamino groups into the 4-position of quinazoline leads to new potent and selective PI3Kδ inhibitors.

Design, Synthesis and Biological Evaluation of Novel Phenylsulfonylurea Derivatives as PI3K/mTOR Dual Inhibitors

Five series of novel phenylsulfonylurea derivatives, 19a⁻d, 20a⁻d, 21a⁻d, 22a⁻d and 23a⁻d, bearing 4-phenylaminoquinoline scaffold were designed, synthesized and their IC₅₀ values against four cancer cell lines (HepG-2, A549, PC-3 and MCF-7) were evaluated. Most compounds showed moderate cytotoxicity activity against the cancer cell lines. Structure⁻activity relationships (SARs) and pharmacological results indicated that introduction of 4-aminoquinoline scaffold and phenylsulfonylurea scaffold were beneficial for anti-tumor activity. Moreover, para-methoxyl substitution of 4-anilino moiety and para-halogen substitution of phenylsulfonylurea have different impacts on different series of compounds. Furthermore, the micromolecule group substitution in the 6-position of the quinoline ring have a slight impact on the cellular activity of the target compounds.

Frontiers in Medicinal Chemistry 2017 in Bern, Switzerland

Sharing capital ideas: The 2017 Frontiers in Medicinal Chemistry (FiMC) conference, organized jointly by the German Chemical Society, the German Pharmaceutical Society, and the Swiss Chemical Society, was held at the Department of Chemistry and Biochemistry of the University of Bern in February 2017. Herein we summarize the many conference highlights, and look forward to the next FiMC meeting, to be held in Jena (Germany) in March 2018.

Discovery of CDZ173 (Leniolisib), Representing a Structurally Novel Class of PI3K Delta-Selective Inhibitors

The predominant expression of phosphoinositide 3-kinase δ (PI3Kδ) in leukocytes and its critical role in B and T cell functions led to the hypothesis that selective inhibitors of this isoform would have potential as therapeutics for the treatment of allergic and inflammatory disease. Targeting specifically PI3Kδ should avoid potential side effects associated with the ubiquitously expressed PI3Kα and β isoforms. We disclose how morphing the heterocyclic core of previously discovered 4,6-diaryl quinazolines to a significantly less lipophilic 5,6,7,8-tetrahydropyrido[4,3-d]pyrimidine, followed by replacement of one of the phenyl groups with a pyrrolidine-3-amine, led to a compound series with an optimal on-target profile and good ADME properties. A final lipophilicity adjustment led to the discovery of CDZ173 (leniolisib), a potent PI3Kδ selective inhibitor with suitable properties and efficacy for clinical development as an anti-inflammatory therapeutic. In vitro, CDZ173 inhibits a large spectrum of immune cell functions, as demonstrated in B and T cells, neutrophils, monocytes, basophils, plasmocytoid dendritic cells, and mast cells. In vivo, CDZ173 inhibits B cell activation in rats and monkeys in a concentration- and time-dependent manner. After prophylactic or therapeutic dosing, CDZ173 potently inhibited antigen-specific antibody production and reduced disease symptoms in a rat collagen-induced arthritis model. Structurally, CDZ173 differs significantly from the first generation of PI3Kδ and PI3Kγδ-selective clinical compounds. Therefore, CDZ173 could differentiate by a more favorable safety profile. CDZ173 is currently in clinical studies in patients suffering from primary Sjögren's syndrome and in APDS/PASLI, a disease caused by gain-of-function mutations of PI3Kδ.

Identification of a Potent, Selective, and Efficacious Phosphatidylinositol 3-Kinase δ (PI3Kδ) Inhibitor for the Treatment of Immunological Disorders

PI3Kδ plays an important role controlling immune cell function and has therefore been identified as a potential target for the treatment of immunological disorders. This article highlights our work toward the identification of a potent, selective, and efficacious PI3Kδ inhibitor. Through careful SAR, the successful replacement of a polar pyrazole group by a simple chloro or trifluoromethyl group led to improved Caco-2 permeability, reduced Caco-2 efflux, reduced hERG PC activity, and increased selectivity profile while maintaining potency in the CD69 hWB assay. The optimization of the aryl substitution then identified a 4'-CN group that improved the human/rodent correlation in microsomal metabolic stability. Our lead molecule is very potent in PK/PD assays and highly efficacious in a mouse collagen-induced arthritis model.