Design, synthesis and biological evaluation of 4-(indolin-1-yl)-6-substituted-pyrido[3,2-d]pyrimidine derivatives as Mnk1/2 inhibitors.

The Mnk-eIF4E axis plays a crucial role in tumor development, and inhibiting Mnk kinases is a promising approach for cancer therapy. Starting with fragment WS23, a series of 4-(indolin-1-yl)-6-substituted-pyrido[3,2-d]pyrimidine derivatives were designed and synthesized. Among these derivatives, compound 15b showed the highest potency with IC50 values of 0.8 and 1.5 nM against Mnk1 and Mnk2, respectively. Additionally, it demonstrated good selectivity among 30 selected kinases. 15b significantly suppressed MOLM-13 and K562 cell lines growth and caused cell cycle arrest. Furthermore, the Western blot assay revealed that 15b effectively downregulated the downstream proteins p-eIF4E, Mcl-1, and c-myc. Additionally, 15b exhibited remarkable stability in rat plasma and rat and human microsomes. In vivo anti-tumor activity study suggested that treatment with 15b suppressed tumor growth in LL/2 syngeneic models. These findings highlight the potential of 15b as a novel and potent Mnks inhibitor, which deserves further investigation.

Targeting Myeloid Leukemia-1 in Cancer Therapy: Advances and Directions.

As a tripartite cell death switch, B-cell lymphoma protein 2 (Bcl-2) family members precisely regulate the endogenous apoptosis pathway in response to various cell signal stresses through protein-protein interactions. Myeloid leukemia-1 (Mcl-1), a key anti-apoptotic Bcl-2 family member, is positioned downstream in the endogenous apoptotic pathway and plays a central role in regulating mitochondrial function. Mcl-1 is highly expressed in a variety of hematological malignancies and solid tumors, contributing to tumorigenesis, poor prognosis, and chemoresistance, making it an attractive target for cancer treatment. This Perspective aims to discuss the mechanism by which Mcl-1 regulates apoptosis and non-apoptotic functions in cancer cells and to outline the discovery and optimization process of potent Mcl-1 modulators. In addition, we summarize the structural characteristics of potent inhibitors that bind to Mcl-1 through multiple co-crystal structures and analyze the cardiotoxicity caused by current Mcl-1 inhibitors, providing prospects for rational targeting of Mcl-1.

Optimization of the synthesis of BET BD2 selective inhibitor XY153.

XY153 is a promising BET BD2 inhibitor with an IC50 value of 0.79 nM against BRD4 BD2. It shows 354-fold selectivity over BRD4-BD1 and 6-fold selectivity over other BET BD2 domains. However, the reported synthesis route of XY153 and its derivatives are extremely poor-yielding. After the synthesis of three key fragments, XY153 can only be obtained with a yield of 1.3 % in the original four-step reaction. In this study, we reported a three-step alternative route in the synthesis process of XY153. The reaction conditions for this route were thoroughly investigated and optimized, resulting in a significantly improved yield of 61.5 %. This efficient synthesis route establishes a robust chemical foundation for the rapid synthesis of XY153 derivatives as BET BD2 inhibitors in the near future.

Construction of Diversified Penta-Spiro-Heterocyclic and Fused-Heterocyclic Frameworks with Potent Antitumor Activity.

Invited for the cover of this issue are Xuewu Liang, Hong Liu and co-workers at the Shanghai Institute of Materia Medica and Shenyang Pharmaceutical University. The image depicts how a rhodium-catalyzed methodology leads to novel penta-spiro/fused-heterocyclic frameworks with potent antitumor activity through C-H activation/[4+1] and [4+2] annulation cascades. Read the full text of the article at 10.1002/chem. 202301553.

Computer-aided drug design course for pharmacy major students in Shenyang Pharmaceutical University following the COVID-19 pandemic: Challenges and opportunities.

The computer-aided drug design (CADD) course that spans biochemistry, computational chemistry, medicinal chemistry, and other cutting-edge sciences is considered an important course by pharmaceutical universities in China. The course teaches students how drugs bind to protein targets and exert their biological activities using computer tools, and covers the basic principles of drug development and optimization. Due to the lockdown and social distancing measures adopted during the coronavirus disease 2019 (COVID-19) pandemic, the CADD course in Shenyang Pharmaceutical University was briefly suspended. Thereafter, it was taught in the online mode by adopting a novel blended teaching method. Through a questionnaire survey and final report assessment, we found that blended teaching might provide an opportunity to stimulate greater motivation and interest in students as well as improve teaching effectiveness and learning outcomes of the course. This study describes how we conducted the CADD course during the COVID-19 period with the intention of providing a reference for other teachers to conduct similar courses.

Construction of Diversified Penta-Spiro-Heterocyclic and Fused-Heterocyclic Frameworks with Potent Antitumor Activity.

Multiple-spiro/fused-heterocyclic frameworks containing indazolone are structurally unique and represent a class of potentially dominant skeletons. In this work, we successfully fulfilled Rh(III)-catalyst mediated substrate- and pH- controlled strategies to construct four novel types of complicated penta-spiro/fused-heterocyclic frameworks via C-H activation/[4+1] and [4+2] annulation cascades. This method had mild reaction conditions, a broad scope of substrates, moderate to good yields, and valuable applications, which could realize for the first time the generation of the novel di-spiro-heterocyclic and multiple fused-heterocyclic products with unique structures. More importantly, novel spiro[cyclohexane-indazolo[1,2-a]indazole] scaffold constructed by this method exhibited potent antitumor activity against a variety of refractory solid tumors and hematological malignancies in vitro. Overall, our work provided new insights into the construction of complex and diverse multiple spiro/fused-heterocyclic systems and offered novel valuable lead compounds for the discovery of antitumor drugs.

Rational design, synthesis and biological evaluation of benzo[d]isoxazole derivatives as potent BET bivalent inhibitors for potential treatment of prostate cancer.

Multivalency is an attractive strategy for effective binding to target protein. Bromodomain and extra-terminal (BET) family features two tandem bromodomains (BD1, BD2), which are considered to be potential new targets for prostate cancer. Herein, we report the rational design, optimization, and evaluation of a class of novel BET bivalent inhibitors based on our monovalent BET inhibitor 7 (Y06037). The representative bivalent inhibitor 17b effectively inhibited the cell growth of LNCaP, exhibiting 32 folds more potency than monovalent inhibitor 7. Besides, 17b induced 95.1 % PSA regression in LNCaP cell at 2 µM. Docking study was further carried out to reveal the potential binding mode of 17b with two BET bromodomains. Our study demonstrates that 17b (Y13021) is a promising BET bivalent inhibitor for the treatment of prostate cancer.

Optimization of BAX trigger site activator BTSA1 with improved antitumor potency and in vitro ADMET properties.

Direct activation of the pro-apoptotic protein BAX represents a potential therapeutic strategy to trigger apoptosis in cancer. Herein, structural optimization of the reported BAX trigger site activator BTSA1 turned out into a series of pyrazolone derivatives, where compound 6d exhibited significantly enhanced antiproliferative effects and apoptosis induction ability compared to BTSA1. Mechanism of action studies revealed that compound 6d could initiate the BAX activation cascade, promoting BAX insertion into mitochondrial membranes and activating MOMP, ultimately leading to the release of cytochrome c and apoptosis. Furthermore, 6d showed significantly improved in vitro stability and CYPs profile compared to BTSA1. This work may lay a foundation to develop potent BAX trigger site activators for the treatment of BAX-expressing malignancies.

Synthesis of Paclitaxel Derivatives for Remote Loading into Liposomes and Improved Therapeutic Effect.

A series of novel paclitaxel derivatives modified by boronic acid according to the characteristics of the interaction between RB(OH)2 and different strapping agents of intraliposomal aqueous phase were designed and synthesized, which were then used to develop remote poorly water-soluble drugs loading into liposomes. Meanwhile, we screened nineteen paclitaxel boronic acid derivatives for their cytotoxic activities against three cancer cell lines (A549, HCT-116 and 4T1) and one normal cell line (LO2), and performed liposome formulation screening of active compounds. Among all the compounds, the liposome of 4d, with excellent drug-encapsulated efficiency (>95% for drug-to-lipid ratio of 0.1 w/w), was the most stable. Furthermore, the liposomes of compound 4d (8 mg/kg, 4 times) and higher dose of compound 4d (24 mg/kg, 4 times) showed better therapeutic effect than paclitaxel (8 mg/kg, 4 times) in the 4T1 tumor model in vivo, and the rates of tumor inhibition were 74.3%, 81.9% and 58.5%, respectively. This study provided a reasonable design strategy for the insoluble drugs to improve their drug loading into liposomes and anti-tumor effect in vivo.

Development of a series of novel Mcl-1 inhibitors bearing an indole carboxylic acid moiety.

The B cell lymphoma protein 2 (Bcl-2) family proteins regulate cell apoptosis by participating in the endogenous apoptosis pathway. As an important anti-apoptotic protein, Myeloid cell leukemia 1 (Mcl-1) is overexpressed in a variety of tumor cells, and targeting this protein has been a promising strategy for cancer therapy. Herein, based on the 1H-indole-5-carboxylic acid structure previously discovered, we have developed a series of novel compounds with increased affinities and selectivity toward Mcl-1 through structure-based drug design. Among those compounds, 26 exerted relatively better affinity and selectivity for Mcl-1 with moderate inhibition in HL-60 cells. Mechanism studies showed that compound 26 could induce cancer cells apoptosis in an Mcl-1-dependent manner. It also exhibited good microsomal and plasma stability with acceptable pharmacokinetics profiles. Furthermore, treatment with target compound in a 4T1 xenograft mouse model significantly suppressed the tumor growth. Overall, the small molecule described herein represents a promising Mcl-1 inhibitor for further study.

Discovery and structure-activity relationship studies of novel Bcl-2/Mcl-1 dual inhibitors with indole scaffold.

The Bcl-2 anti-apoptotic proteins were widely overexpressed in diverse tumor cells, especially for Bcl-2 and Mcl-1, which regarding as important targets of apoptosis induction and resistance of chemotherapy. We identified novel Bcl-2/Mcl-1 dual inhibitors with indole scaffold by the optimization of hit 1. Structure modification against several moieties including hydrophobic fragment, side chain and benzoic acid fragment was conducted and the structure-activity relationship was analyzed. The representative compound 12f exhibited sub-micromolar binding affinities to Bcl-2/Mcl-1 without binding affinity to Bcl-XL. Mechanism of action studies suggested that compound 12f dose-dependently triggered apoptosis in HL-60 cells. Compound 12f represents a novel Bcl-2/Mcl-1 dual inhibitor which deserving further study.

Artesunate improves venetoclax plus cytarabine AML cell targeting by regulating the Noxa/Bim/Mcl-1/p-Chk1 axis.

Venetoclax plus cytarabine therapy is approved for elderly acute myeloid leukemia (AML) patients and needs further improvement. We studied the mechanisms of venetoclax plus cytarabine treatment and searched for a third agent to enhance their effects. Cytarabine induces S phase arrest-mediated DNA damage with activation of DNA replication checkpoint kinase 1 (Chk1) through phosphorylation, while venetoclax induces B cell lymphoma 2 (Bcl-2)-interacting mediator of cell death (Bim)-mediated apoptotic DNA damage. Myeloid cell leukemia-1 (Mcl-1) plays negative roles in both events by sequestering Bim and accelerating Chk1 phosphorylation. Venetoclax releases Bim from Bcl-2 with increased Bim binding to Mcl-1. Artesunate, an antimalaria drug, induces Noxa to replace Bim from Mcl-1 and induces synergistic apoptosis with venetoclax accompanied with Mcl-1 reduction. Silencing Mcl-1 or adding venetoclax/artesunate diminishes the cytarabine resistance pathway p-Chk1. The triple combination exhibits S phase arrest with enhanced DNA damage, improves AML colony formation inhibition, and prolongs survival of two mice xenograft models compared to the venetoclax/cytarabine dual combination. Artesunate serves as a bridge for venetoclax and cytarabine combination by Noxa and Bim-mediated apoptosis and Mcl-1 reduction. We provide a new triple combination for AML treatment by targeting the Noxa/Mcl-1/Bim axis to reverse Mcl-1/p-Chk1 resistance of cytarabine therapy.

Trends in targeting Bcl-2 anti-apoptotic proteins for cancer treatment.

Apoptosis is the major mode of programmed cell death, which conduces to maintain tissue homeostasis, clearance of abnormal cells and development of organisms. Over the past two decades, great progress and significant clinical benefits in cancer treatment have been made by targeting Bcl-2 anti-apoptotic proteins. However, with the deep research of clinic, the therapeutic value of single target inhibitors is restricted due to the limited monotherapy activity, potential and complex drug resistance as well as monotherapy safety. This review focuses on recent advance in discovery of novel apoptosis inducers targeting Bcl-2 anti-apoptotic proteins aiming to overcome existing therapeutic limitations, and introduce the strategies and advanced technologies in the drug design and optimization.

Small molecules targeting γ-secretase and their potential biological applications.

The γ-secretase is a large transmembrane protein complex composed of four distinct units. It has aroused numerous attention over the past two decades as its intriguing role in mediating intramembrane proteolysis. γ-Secretase controls the cleavage of a broad ranged substrates, part of which have implicated in the pathogenesis of Alzheimer's disease, inflammation, and tumorigenesis. The disclosure of the atomic structure of the γ-secretase complex through cryo-EM in recent years has facilitated the understanding of its physiological roles, as well as enabled rational design of novel γ-secretase targeting molecules. This review highlights the recent progress of γ-secretase inhibitors and modulators under either clinical or preclinical stages, as well as their potential uses against various biological indications.

Discovery of Novel Indole Derivatives as Fructose-1,6-bisphosphatase Inhibitors and X-ray Cocrystal Structures Analysis.

Liver fructose-1,6-bisphosphatase (FBPase) is a key enzyme in the gluconeogenesis, and its inhibitors are expected to be novel antidiabetic agents. Herein, a series of new indole and benzofuran analogues were designed and synthesized to evaluate the inhibitory activity against FBPase. As a result, the novel FBPase inhibitors bearing N-acylsulfonamide moiety on the 3-position of the indole-2-carboxylic acid scaffold (compounds 22f and 22g) were identified with IC50s at the submicromolar levels. Three X-ray crystal structures of the complexes were solved and revealed the structural basis for the inhibitory activity. The chemoinformatics analysis further disclosed the distinct binding features of this class of inhibitors, providing an insight for further modifications to create structurally distinct FBPase inhibitors with high potency and drug-like properties.

Optimization of 4,6-Disubstituted Pyrido[3,2-d]pyrimidines as Dual MNK/PIM Inhibitors to Inhibit Leukemia Cell Growth.

Mitogen-activated protein kinase-interacting kinases (MNKs) and provirus integration in maloney murine leukemia virus kinases (PIMs) are downstream enzymes of cell proliferation signaling pathways associated with the resistance of tyrosine kinase inhibitors. MNKs and PIMs have complementary effects to regulate cap-dependent translation of oncoproteins. Dual inhibitors of MNKs and PIMs have not been developed. We developed a novel 4,6-disubstituted pyrido[3,2-d]pyrimidine compound 21o with selective inhibition of MNKs and PIMs. The IC50's of 21o to inhibit MNK1 and MNK2 are 1 and 7 nM and those to inhibit PIM1, PIM2, and PIM3 are 43, 232, and 774 nM, respectively. 21o inhibits the growth of myeloid leukemia K562 and MOLM-13 cells with GI50's of 2.1 and 1.2 µM, respectively. 21o decreases the levels of p-eIF4E and p-4EBP1, the downstream products of MNKs and PIMs, as well as cap-dependent proteins c-myc, cyclin D1, and Mcl-1. 21o inhibits the growth of MOLM-13 cell xenografts without causing evident toxicity. 21o represents an innovative dual MNK/PIM inhibitor with a good pharmacokinetic profile.

Design, synthesis and biological evaluation of dual Bcl-2/Mcl-1 inhibitors bearing 2-(1H-indol-4-yl)benzoic acid scaffold.

The anti-apoptotic protein inhibitors of the B cell lymphoma 2 (Bcl-2) family have been developed as new anticancer therapies. Numerous studies illustrated the great potential in the development of dual Bcl-2/myeloid cell leukemia 1 (Mcl-1) inhibitors. Herein, we reported a series of Bcl-2/Mcl-1 inhibitors that optimized from a hit compound 1 via structure-based rational design. The biological evaluation suggested that most compounds exhibited potent binding affinities at submicromolar to both Bcl-2 and Mcl-1 without any Bcl-xL binding affinities, especially compound 9o, with a Ki value of 0.07 µM to Mcl-1 and 0.66 µM to Bcl-2, that has great potential for developing dual inhibitors targeting Bcl-2 and Mcl-1.

Design, synthesis and biological evaluation of selective histone deacetylase 6 (HDAC6) inhibitors bearing benzoindazole or pyrazoloindazole scaffold as surface recognition motif.

A series of compounds were designed and synthesized based on the compound 11i bearing phenylpyrazole scaffold with histone deacetylase 6 (HDAC6) inhibitory activity. Most of the compounds showed considerable inhibitory activity against HDAC6 and compound A16 with good inhibitory activity was found therein. We further found that A16 had an inhibitory effect on inflammatory mediators (NO, TNF-α, IL-6) involved in inflammatory response and neuroendocrine regulation. In addition, A16 has a certain neuroprotective effect on PC12 cells injured by hydrogen peroxide. Acute toxicity assay showed that the LD50 of A16 was 274.47 mg/kg in mouse model. Furthermore, A16 displayed good stability properties in microsomes and plasma.

Studying Histone Deacetylase Inhibition and Apoptosis Induction of Psammaplin A Monomers with Modified Thiol Group.

Psammaplin A (PsA) is a bromotyrosine disulfide dimer with histone deacetylase (HDAC) inhibition and acts through reduced monomer PsA-SH. We studied the connection of HDAC inhibition, cell growth inhibition, and apoptosis induction of PsA-SH by modifying the -SH group with deletion (6a) or replacement with hydroxamic acid (10b) or benzamide (12g). PsA-SH inhibits HDAC1/2/3 and 6a loses the HDAC inhibition ability. 10b inhibits HDAC1/2/3/6 while 12g shows selective inhibition of HDAC3. PsA-SH and 10b, but neither 6a nor 12g, induce apoptosis in human leukemia HL-60 cells associated with increased acetylation of Histone H3. PsA-SH and 10b inhibit growth of several solid tumor cell lines in vitro and Lewis lung cancer cell growth in vivo. PsA-SH is a simple scaffold for developing selective HDAC inhibitors and induces apoptosis through inhibiting HDAC1/2.

Application of sulfoximines in medicinal chemistry from 2013 to 2020.

In recent years, interest in sulfoximine chemistry has been greatly increased. For example, at least three sulfoximine containing drugs BAY 1143572, BAY 1251152 and AZD6738 have entered the clinic. Despite the increasing interest in sulfoximines and their chemistry, the routine application of this structure in drug discovery is still hampered due to limited experience in physicochemical and in vitro parameters of sulfoximines. Therefore, we reviewed all relevant articles from 2013 to the present in terms of potency and pharmacokinetic properties in order to support the addition of the sulfoximine component to the toolbox of medicinal chemists.