Diastereoselective Synthesis of 4-Hydroxy-2-quinolinones via Formal [2 + 4] Cycloaddition Reactions Using α-Diazo Pyrazoleamides as C2 Synthons.

A rhodium-catalyzed highly stereoselective formal [2 + 4]-cycloaddition reaction of α-diazo pyrazoleamides and 2-aminophenyl ketones that produces 4-hydroxy-2-quinolinones in good yields with excellent diastereoselectivities has been developed. A pyrazolium ylide species that is generated from α-diazo pyrazoleamides is used as a C2 synthon for this cycloaddition. This protocol offers an efficient approach to a variety of 4-hydroxy-2-quinolinones featuring sequential quaternary centers.

Discovery and Optimization of Novel Biphenyl Derivatives Bearing Cyclopropyl Linkage as Potent Programmed Cell Death-1/Programmed Cell Death-Ligand 1 Inhibitors.

A series of novel compounds bearing a cyclopropyl linkage were designed, synthesized, and evaluated as programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) inhibitors. An optimized compound (1S,2S)-A25 showed potent inhibitory activity against the PD-1/PD-L1 interaction (IC50 = 0.029 µM) with a selected binding affinity with PD-L1 (KD = 1.554 × 10-1 µM). Additionally, under the co-culture with H460/Jurkat cells, (1S,2S)-A25 can reduce the survival of H460 cells in a concentration-dependent way. A liver microsomal assay revealed that (1S,2S)-A25 had favorable metabolic stability. Furthermore, (1S,2S)-A25 displayed favorable pharmacokinetic properties (oral bioavailability of 21.58%) and potent antitumor potency in a LLC1 lung carcinoma model without observable side effects. Data from the flow cytometry and enzyme-linked immunosorbent assays demonstrated that (1S,2S)-A25 suppressed the tumor growth by activating the immune microenvironment. Our study suggests that (1S,2S)-A25 is a promising lead compound for the further development of PD-1/PD-L1 inhibitors.

Design, synthesis and biological evaluation N2-(2-alkyoxy-6-aliphatic aminopyridin-3-yl)-2,4-diaminepyrimidine derivatives bearing acylamino or DBTD 'head' as potential ALK inhibitors.

Aiming to develop promising ALK inhibitors, two series of N2-(2-alkyoxy-6-aliphatic aminopyridin-3-yl)-2,4-diaminepyrimidine derivatives (22a-x and 23a-d) were designed according to scaffold hopping and bioisosterism principles. All compounds were efficiently synthesized by concise reactions and anti-proliferative activities on ALK-addicted H2228, Karpas299 cells and EGFR-expressive A549 cell were evaluated by MTT assay. Several compounds exhibited potential cytotoxic activities with IC50 values below 0.10 µM. Five compounds (22g, 22h, 22l, 22s and 23a) were selected for further enzymatic determination, resulting in the discovery of 22l against ALK and ALKL1196M with IC50 values of 2.1 nM and 3.8 nM. Particularly, western blot and cell apoptosis assays identified 22l as a promising ALK inhibitor, which was capable of obviously inhibiting cellular ALK activity and inducing cell apoptosis. Eventually, molecular docking modes of 22l with ALK confirmed structural basis in accordance with the SARs analysis.

Discovery and optimization of tetrahydropyrido[4,3-d]pyrimidine derivatives as novel ATX and EGFR dual inhibitors.

In order to discovery autotaxin (ATX) and EGFR dual inhibitors with potential therapeutic effect on IPF-LC, a series of novel tetrahydropyrido[4,3-d]pyrimidine derivatives possessing semicarbazones moiety were designed and synthesized. The preliminary investigation at the cellular level indicated six compounds (7h, 8a, 8c, 8d, 9a and 9d) displayed preferable anti-tumor activities against A549, H1975, MKN-45 and SGC cancer cells. Further enzymatic assay against EGFR kinase identified 8a and 9a as promising hits with IC50 values of 18.0 nM and 24.2 nM. Meanwhile, anti-inflammatory assessment against cardiac fibroblasts (CFs) cell and RAW264.7 macrophages led to the discovery of candidate 9a, which exhibited considerable potency both on inhibition rate of 77% towards CFs and on reducing NO production to 1.05 µM at 10 µg/mL. Simultaneously, 9a indicated preferable potency towards ATX with IC50 value of 29.1 nM. Significantly, a RT-PCR study revealed the function of 9a to down-regulate the mRNA expression of TGF-ß and TNF-α in a dose-dependent manner. The molecular docking analysis together with the pharmacological studies validated 9a as a potential ATX and EGFR dual inhibitor for IPF-LC treatments.

Synthesis, biological evaluation and molecular modeling of imidazo[1,2-a]pyridine derivatives as potent antitubulin agents.

Two series of novel 5,7-diarylimidazo[1,2-a]pyridine-8-carbonitrile derivatives (3a-3q and 7a-7n) were designed by modification of CA-4 pharmacophore to develop colchicine targeted antitubulin agents. All compounds were efficiently synthesized and evaluated for their cytotoxicity against five selected cancer cell lines (HT-29, H460, A549, MKN-45 and SMMC-7721) which got an insight in structure and activity relationships (SARs). Several molecules (7e, 7f, 7h-7j and 7m) were disclosed to exhibit promising antiproliferative activity with IC50 values in double-digit nanomolar degree. Optimization toward these compounds led to the discovery of a promising lead 7e, which showed noteworthy potency with IC50 value ranging from 0.01 to 3.2µM superior to CA-4 and Crolibulin. Importantly, immunofluorescence staining and colchcine competitive binding assay revealed that microtubule dynamics was disrupted by 7e by binding at the colchicine site of tubulin. Moreover, molecular docking studies suggested the binding of this mimic at colchcine-binding site is similar to Crolibulin, as was in conformity with the observed SARs for these compounds.

Discovery and Optimization of Novel 5-Indolyl-7-arylimidazo[1,2-a]pyridine-8-carbonitrile Derivatives as Potent Antitubulin Agents Targeting Colchicine-binding Site.

Aiming at development of potent antitubulin agents targeting colchicine-binding site, a series of novel 5-indolyl-7-arylimidazo[1,2-a]pyridine-8-carbonitrilederivatives (5a-5v and 7a-7h) were designed based on bioisosterism and hybridization strategies. All these compounds were concisely synthesized via a three-step process and examined against five human cancer cell lines (HT-29, A549, MKN-45, MDA-MB-231 and SMMC-7721) along with a normal human cell (L02) in vitro. A structure-activity relationships (SARs) study was carried out and optimization towards this series of compounds in cellular assay resulted in the discovery of 5k, which displayed similar or better antitumor potency against the tested cancer cells with IC50 value ranging from 0.02 to 1.22 µM superior to CA-4 and Crolibulin. Significantly, a cell cycle study disclosed the ability of 5k to arrest cell cycle at the G2/M phase, and immunofluorescence assay as well as a colchicine competition assay revealed that tubulin polymerization was disturbed by 5k by binding to the colchicine site. Moreover, the molecular modeling mode showed the posture of 5k and Crolibulin was similar in the colchcine-binding pocket of tubulin as identified with the SARs and pharmacological results. Together, all these results rationalized 5k might serve as a promising lead for a novel class of antitubulin agents for cancer treatments.

Design, synthesis and biological evaluation of novel 4-(2-fluorophenoxy)quinoline derivatives as selective c-Met inhibitors.

Two novel series of 6,7-disubstituted-4-(2-fluorophenoxy)quinoline derivatives bearing 1H-imidazole-4-carboxamido or (E)-3-hydrosulfonylacrylamido motifs (16-31 and 32-42) were designed, synthesized and evaluated for their in vitro cytotoxic activity. Most of the compounds exhibited moderate to excellent potency against tested three cell lines, and fifteen compounds were further examined for their inhibitory activity against c-Met kinase. The most promising compound 16 (c-Met kinase [IC50]=1.1nM) demonstrated high selectivity and remarkable cytotoxicity against HT-29, MKN-45 and A549 cells with IC50 values of 0.08, 0.22 and 0.07µM, which were 3.1-, 1.4- and 2.1-fold more active than Foretinib. The preliminary structure-activity relationships as well as molecular docking disclosed that 1H-imidazole-4-carboxamido as a linker was of great importance for the antitumor activity.