Discovery andw biological evaluation of novel 6,7-disubstituted-4-(2-fluorophenoxy)quinoline derivatives possessing 1,2,3-triazole-4-carboxamide moiety as c-Met kinase inhibitors

A series of 6,7-disubstituted-4-(2-fluorophenoxy)quinoline derivatives possessing 1,2,3-triazole-4-carboxamide moiety were designed, synthesized and evaluated for their in vitro biological activities against c-Met kinase and five typical cancer cell lines (A549, H460, HT-29, MKN-45 and U87MG). Most compounds showed moderate to excellent antiproliferative activity. In this study, a promising compound 34, with a c-Met IC₅₀ value of 1.04 nM, was identified as a multitargeted receptor tyrosine kinase inhibitor. The SAR analyses indicated that compounds with halogen group, especially fluoro group, at 4-position on the phenyl ring (moiety B) have potent antitumor activity, and methylation on the 5-atom linker played an important role in the c-Met enzymatic activity.     

Target ROS to induce apoptosis and cell cycle arrest by 5,7-dimethoxy-1,4-naphthoquinone derivative

The 1,4-naphthoquinone derivatives bearing 5,7-dimethoxyl moiety were designed, synthesized, and tested as the antitumor agents against five human cancer cell lines (A549, Hela, HepG2, NCI-H460 and HL-60). All the compounds are described herein for the first time. The structure-activity relationships indicated that the presence of chlorine atom at the 2-position was crucial for the antiproliferative activity. Further, the electrochemical properties of the representative compounds (7e, 8e and 9e) were evaluated and a definite correlation between the redox potential and the antiproliferative activity. The most potent compound 9e displayed significant anti-leukemic activity with IC₅₀ value of 3.8?μM in HL-60 cells and weak cytotoxicity with IC₅₀ of 40.7?μM in normal cells WI-38. In mechanistic study for 9e, the increased numbers of apoptotic cells and increased cell population at G2/M phase correlated with ROS generation. Together, our results suggested that the derivatives of 2-chlorine-1,4-naphthoquinone might be the promising candidates for the treatment of promyelocytic leukemia.     

Synthesis and biochemical evaluation of a range of (4-substituted phenyl)sulfonate derivatives of 4-hydroxybenzyl imidazole-based compounds as potent inhibitors of 17α-hydroxylase/17,20-lyase (P45017α) derived from rat testicular microsomes

We report the synthesis, biochemical evaluation and rationalisation of the inhibitory activity of a range of (4-substituted phenyl)sulfonate derivatives of 4-hydroxybenzyl imidazole against the two components of 17α-hydroxylase/17,20-lyase (P450_17α), namely, 17α-hydroxylase (17α-OHase) and 17,20-lyase (lyase). The results show the compounds to be highly potent inhibitors with limited selectivity towards the lyase component [e.g., toluene-4-sulfonic acid 4-imidazol-1-ylmethyl-phenyl ester (4) possessed an IC₅₀ value of 40 nM against 17α-OHase and 30 nM against lyase].     

Development of novel phenoxy-diketopiperazine-type plinabulin derivatives as potent antimicrotubule agents based on the co-crystal structure

The co-crystal structure of Compound 6b with tubulin was prepared and solved for indicating the binding mode and for further optimization. Based on the co-crystal structures of tubulin with plinabulin and Compound 6b, a total of 27 novel A/B/C-rings plinabulin derivatives were designed and synthesized. Their biological activities were evaluated against human lung cancer NCI-H460 cell line. The optimum phenoxy-diketopiperazine-type Compound 6o exhibited high potent cytotoxicity (IC₅₀ = 4.0 nM) through SAR study of three series of derivatives, which was more potent than plinabulin (IC₅₀ = 26.2 nM) and similar to Compound 6b (IC₅₀ = 3.8 nM) against human lung cancer NCI-H460 cell line. Subsequently, the Compound 6o was evaluated against other four human cancer cell lines. Both tubulin polymerization assay and immunofluorescence assay showed that Compound 6o could inhibit microtubule polymerization efficiently. Furthermore, theoretical calculation of the physical properties and molecular docking were elucidated for these plinabulin derivatives. The binding mode of Compound 6o was similar to Compound 6b based on the result of molecular docking. The theoretical calculated LogPo/w and PCaco of Compound 6o were better than Compound 6b, which could enhance its cytostatic activity. Therefore, Compound 6o might be developed as a novel potent anti-microtubule agent.     

Discovery of novel 6,7-disubstituted-4-phenoxyquinoline derivatives bearing 5-(aminomethylene)pyrimidine-2,4,6-trione moiety as c-Met kinase inhibitors

A series of novel quinoline derivatives bearing 5-(aminomethylene)pyrimidine-2,4,6-trione moiety were designed, synthesized, and evaluated for their c-Met kinase inhibitory activities and antiproliferative activities against 5 cancer cell lines (HT-29, H460, MKN-45, A549, and U87MG) in vitro. Most compounds showed moderate to excellent potency, with the most promising analogue 45 (c-Met half-maximal inhibitory concentration [IC₅₀] = 1.15 nM) showing high selectivity versus 5 other tyrosine kinases, VEGFR-2, Flt-3, PDGFR-β, c-Kit, and EGFR. Structure–activity relationship studies indicated that electron-donating groups on the phenyl ring at the 3-position of pyrimidine-2,4,6-trione were required to increase the electron density on the 5-(aminomethylene)pyrimidine-2,4,6-trione moiety.     

Discovery of novel 4-(2-fluorophenoxy)quinoline derivatives bearing 4-oxo-1,4-dihydrocinnoline-3-carboxamide moiety as c-Met kinase inhibitors

A series of novel 4-(2-fluorophenoxy)quinoline derivatives containing 4-oxo-1,4-dihydrocinnoline-3-carboxamide moiety were designed, synthesized and evaluated for their in vitro biological activities against c-Met kinase and six typical cancer cell lines (A549, H460, HT-29, MKN-45, U87MG and SMMC-7721). All the prepared compounds showed moderate to excellent antiproliferative activity, and the analysis of their structure–activity relationships indicated that 2-chloro or 2-trifluoromethyl substituted phenyl group on the 1-position of cinnoline ring was more favorable for antitumor activity. In this study, a promising compound 33, with a c-Met IC₅₀ value of 0.59 nM, was identified as a multitargeted receptor tyrosine kinase inhibitor.     

Synthesis and biological evaluation of trisubstituted imidazole derivatives as inhibitors of p38alpha mitogen-activated protein kinase

A series of trisubstituted imidazole derivatives containing a 4-fluorophenyl group, a pyrimidine ring, and a CN- or CONH₂-substituted benzyl moiety have been synthesized and evaluated for p38α MAP kinase inhibitory activity. Among them, compounds 22c, 27b, and 28b inhibited p38α MAP kinase with IC₅₀ values 27.6, 28, and 31 nM, respectively.     

Design,synthesis and biological evaluation of novel 6,7-disubstituted-4-phenoxyquinoline derivatives bearing 4-oxo-3,4-dihydrophthalazine-1-carboxamide moieties as c-Met kinase inhibitors

A series of 6,7-disubstituted-4-phenoxyquinoline derivatives bearing 4-oxo-3,4-dihydrophthalazine-1-carboxamide moieties were designed, synthesized and evaluated for their c-Met kinase inhibition and cytotoxicity against H460, MKN-45, HT-29 and MDA-MB-231 cancer cell lines in vitro. Most compounds displayed good to excellent potency against four tested cancer cell lines as compared with foretinib. The SAR analyses indicated that compounds with halogen groups, especially fluoro groups at 4-position on the phenyl ring (moiety B) were more effective than those with nitro groups or methoxy groups. In this study, a promising compound 33 (c-Met IC₅₀ = 1.63 nM) was identified, which showed the most potent antitumor activities with IC₅₀ values of 0.055 μM, 0.071 μM, 0.13 μM, and 0.43 μM against H460, MKN-45, HT-29 and MDA-MB-231 cell lines, respectively.     

Synthesis and CYP26A1 inhibitory activity of novel methyl 3-[4-(arylamino)phenyl]-3-(azole)-2,2-dimethylpropanoates

The role of all-trans-retinoic acid (ATRA) in the development and maintenance of many epithelial and neural tissues has raised great interest in the potential of ATRA and related compounds (retinoids) as pharmacological agents, particularly for the treatment of cancer, skin, neurodegenerative and autoimmune diseases. The use of ATRA or prodrugs as pharmacological agents is limited by a short half-life in vivo resulting from the activity of specific ATRA hydroxylases, CYP26 enzymes, induced by ATRA in liver and target tissues. For this reason retinoic acid metabolism blocking agents (RAMBAs) have been developed for treating cancer and a wide range of other diseases.The synthesis, CYP26A1 inhibitory activity and molecular modeling studies of novel methyl 3-[4-(arylamino)phenyl]-3-(azole)-2,2-dimethylpropanoates are presented. From this series of compounds clear SAR can be derived for 4-substitution of the phenyl ring with electron-donating groups more favourable for inhibitory activity. Both the methylenedioxyphenyl imidazole (17, IC₅₀ = 8 nM) and triazole (18, IC₅₀ = 6.7 nM) derivatives were potent inhibitors with additional binding interactions between the methylenedioxy moiety and the CYP26 active site likely to be the main factor. The 6-bromo-3-pyridine imidazole 15 (IC₅₀ = 5.7 nM) was the most active from this series compared with the standards liarozole (IC₅₀ = 540 nM) and R116010 (IC₅₀ = 10 nM).     

Discovery and optimization of novel 4-phenoxy-6,7-disubstituted quinolines possessing semicarbazones as c-Met kinase inhibitors

A novel series of N¹-(3-fluoro-4-(6,7-disubstituted-quinolin-4-yloxy)phenyl)-N⁴-arylidenesemicarbazide derivatives were synthesized and evaluated for their c-Met kinase inhibition and cytotoxicity against A549, HT-29, MKN-45 and MDA-MB-231 cancer cell lines in vitro. Several potent compounds were further evaluated against three other cancer cell lines (U87MG, NCI-H460 and SMMC7721). Most of compounds tested exhibited moderate to excellent activity. The studies of SARs identified the most promising compound 28 (c-Met IC₅₀ = 1.4 nM) as a c-Met kinase inhibitor. In this study, a promising compound 28 was identified, which displayed 2.1-, 3.3-, 48.4- and 3.6-fold increase against A549, HT-29, U87MG and NCI-H460 cell lines, respectively, compared with that of Foretinib.     

A new series of aryl sulfamate derivatives: Design,synthesis, and biological evaluation

Steroid sulfatase (STS) has recently emerged as a drug target for management of hormone-dependent malignancies. In the present study, a new series of twenty-one aryl amido-linked sulfamate derivatives 1a-u was designed and synthesized, based upon a cyclohexyl lead compound. All members were evaluated as STS inhibitors in a cell-free assay. Adamantyl derivatives 1h and 1p-r were the most active with more than 90% inhibition at 10 µM concentration and, for those with the greatest inhibitory activity, IC₅₀ values were determined. These compounds exhibited STS inhibition within the range of ca 25–110 nM. Amongst them, compound 1q possessing a o-chlorobenzene sulfamate moiety exhibited the most potent STS inhibitory activity with an IC₅₀ of 26 nM. Furthermore, to assure capability to pass through the cell lipid bilayer, compounds with low IC₅₀ values were tested against STS activity in JEG-3 whole-cell assays. Consequently, 1h and 1q demonstrated IC₅₀ values of ca 14 and 150 nM, respectively. Thus, compound 1h is 31 times more potent than the corresponding cyclohexyl lead (IC₅₀ value = 421 nM in a JEG-3 whole-cell assay). Furthermore, the most potent STS inhibitors (1h and 1p-r) were evaluated for their antiproliferative activity against the estrogen-dependent breast cancer cell line T-47D. They showed promising activity with single digit micromolar IC₅₀ values (ca 1–6 µM) and their potency against T-47D cells was comparable to that against STS enzyme. In conclusion, this new class of adamantyl-containing aryl sulfamate inhibitor has potential for further development against hormone-dependent tumours.     

Fragment-based modification of 2,4-diarylaminopyrimidine derivatives as ALK and ROS1 dual inhibitors to overcome secondary mutants

In order to explore novel ALK and ROS1 dual inhibitors capable of overcoming crizotinib-resistant mutants, two series of 2,4-diarylaminopyrimidine derivatives were designed, synthesized and evaluated for their in vitro cytotoxic activity. In this work, we retained the 2,4-diarylaminopyrimidine scaffold and derivatize the DAAP scaffold with sulfonyl and acrylamide moieties to extend the structure–activity relationship (SAR) study. To our delight, some compounds exhibited excellent inhibitory activity with a double-digit nanomolar level in MTT assay. Four compounds were selected for enzymic assays further, the results led to the identification of a potent ALK and ROS1 dual inhibitor X-17, with IC₅₀ values of 3.7 nM, 2.3 nM, 8.9 nM and 1.9 nM against ALK, ALK^L1196M, ALK^G1202R and ROS1, respectively. Ultimately, the molecular docking studies on X-17 clearly disclosed reasonable and optimal binding interactions with ALK.     

Development of 6-arylcoumarins as nonsteroidal progesterone antagonists. Structure–activity relationships and fluorescence properties

Progesterone is involved in multiple physiological processes, including female reproduction, via binding to the progesterone receptor (PR). We have developed 6-arylcoumarins such as 5 and 6 as non-steroidal PR antagonists with receptor-binding-dependent fluorescence. In this study, we investigated the structure–activity relationships and fluorescence properties of coumarin derivatives bearing a heterocyclic aromatic moiety. Among these derivatives, 7c (IC₅₀: 34 nM) and 10b (IC₅₀: 24 nM) showed more potent PR-antagonistic activity than lead compounds 5 (IC₅₀: 500 nM) and 6 (IC₅₀: 65 nM) in alkaline phosphatase (AP) assay. Compound 9b showed solvent-dependent fluorescence intensity, exhibiting strong fluorescence in the presence of PR LBD only in buffer solution. On the other hand, 10b showed a solvent-dependent shift of the fluorescence maximum wavelength in the presence of PR LBD. These results indicate that 6-arylcoumarin will be a useful scaffold for PR antagonists and fluorescent probes targeting PR.     

Novel anthraquinone based chalcone analogues containing an imine fragment: Synthesis,cytotoxicity and anti-angiogenic activity

A new class of imine derivatives of hybrid chalcone analogues containing anthraquinone scaffold was synthesized and evaluated for their in vitro cytotoxic activity against HeLa, LS174, and A549 cancer cells. The compound 5n with furan ring linked to imino group showed potent activity against all target cells with IC₅₀ values ranging from 1.76 to 6.11 μM. A mode of action study suggested that compounds induced changes typical for apoptosis in HeLa cells. The most active compounds inhibited tubulogenesis and 5h was found to exhibit a strong anti-angiogenic effect.     

Toward discovery of mutant EGFR inhibitors; Design,synthesis and in vitro biological evaluation of potent 4-arylamino-6-ureido and thioureido-quinazoline derivatives

A new series of 4-anilinoquinazolines with C-6 ureido and thioureido side chains and various substituents at the C-4 anilino moiety was designed, synthesized and evaluated as wild type (WT) and mutant EGFR inhibitors. Most of the compounds inhibited EGFR kinase wild type (EGFR WT) with IC₅₀ values in the low nanomolar range (<0.495–9.05 nM) and displayed more potent cytotoxic effect in BaF/3 expressing EGFR WT than reference compound gefitinib. The anti-proliferative effect of all synthesized compounds against gefitinib insensitive double mutant cell lines Ba/F3 expressing Del19/T790M and Ba/F3 expressing L858R/T790M were assayed. Compounds 4d, 6f, 7e showed significant inhibition (IC₅₀ = 1.76–2.38 μM) in these mutant lines and significant Her2 enzyme inhibition (IC₅₀ = 19.2–40.6 nM) compared to lapatinib (60.1 nM). The Binding mode of compounds 6d, 6f, 7a, 7b and 8b were demonstrated. Furthermore, growth inhibition against gefitinib insensitive cell lines PC9-GR4 (Del19/T790M) were tested, compounds 6f and 7e showed about eight and three folds respectively greater potency than gefitinib. Our structure–activity relationships (SAR) studies suggested that presence of ethyl piperidino urea/thiourea at 6-position and bulky group of (3-chloro-4-(3-fluorobenzyloxy)phenyl)amino at 4-position of quinazoline may serve as promising scaffold for developing inhibitors against wild type and mutant EGFR.     

Synthesis and biological evaluation of 3-tetrazolo steroidal analogs: Novel class of 5α-reductase inhibitors

In the present study, a series of steroidal tetrazole derivatives of androstane and pregnane have been prepared in which the tetrazole moiety was appended at C-3 and 17a-aza locations. 3-Tetrazolo-3,5-androstadien-17-one (6), 3-tetrazolo-19-nor-3,5-androstadien-17-one (10), 3-tetrazolo-3,5-pregnadien-20-one (14), 17a-substituted 3-tetrazolo-17a-aza-d-homo-3,5-androstadien-17-one (26–31) and 3-(2-acetyltetrazolo)-17a-aza-d-homo-3,5-androstadien-17-one (32) were synthesized from dehydroepiandrosterone acetate (1) through multiple synthetic steps. Some of the synthesized compounds were evaluated for their in vitro 5α-reductase (5AR) inhibitory activity by measuring the conversion of [³H] androstenedione in human embryonic kidney (HEK) cells. In vivo 5α-reductase inhibitory activity also showed a significant reduction (p <0.05) in rat prostate weight. The most potent compound 14 showed 5AR-2 inhibition with IC₅₀ being 15.6 nM as compared to clinically used drug finasteride (40 nM). There was also a significant inhibition of 5AR-1 with IC₅₀ 547 nM compared to finasteride (453 nM).     

8-Substituted 2-alkynyl-N9-propargyladenines as A2A adenosine receptor antagonists

Structure–activity relationships of 2-alkynyladenine derivatives were explored by varying substituents at the 9-, 8- and 2-positions of the purine moiety in order to optimize A_2A adenosine receptor antagonist activity in vitro. A propargyl group at the 9-position was found to be important for A_2A antagonist activity, and the introduction of a halogen, aryl, or heteroaryl at the 8-position further enhanced activity. A series of 8-substituted 2-alkynyl-N⁹-propargyladenine derivatives exhibited potent antagonist activity, with IC₅₀ values in the low nM range. Compound 4a from this series was found to be orally active at a dose of 3 mg/kg in a mouse catalepsy model and a 6-hydroxydopamine-lesioned rat model of Parkinson’s disease.     

Structure based drug design and in vitro metabolism study: Discovery of N-(4-methylthiophenyl)-N,2-dimethyl-cyclopenta[d]pyrimidine as a potent microtubule targeting agent

We report a series of tubulin targeting agents, some of which demonstrate potent antiproliferative activities. These analogs were designed to optimize the antiproliferative activity of 1 by varying the heteroatom substituent at the 4′-position, the basicity of the 4-position amino moiety, and conformational restriction. The potential metabolites of the active compounds were also synthesized. Some compounds demonstrated single digit nanomolar IC₅₀ values for antiproliferative effects in MDA-MB-435 melanoma cells. Particularly, the S-methyl analog 3 was more potent than 1 in MDA-MB-435 cells (IC₅₀?=?4.6?nM). Incubation of 3 with human liver microsomes showed that the primary metabolite of the S-methyl moiety of 3 was the methyl sulfinyl group, as in analog 5. This metabolite was equipotent with the lead compound 1 in MDA-MB-435 cells (IC₅₀?=?7.9?nM). Molecular modeling and electrostatic surface area were determined to explain the activities of the analogs. Most of the potent compounds overcome multiple mechanisms of drug resistance and compound 3 emerged as the lead compound for further SAR and preclinical development.     

Synthesis and in vitro antitumor activity of new 4,5-dihydropyrazole derivatives

A series of 3,5-diaryl-4,5-dihydropyrazole regioisomers, and their 1-acetylated derivatives, bearing a 3,4,5-trimethoxyphenyl moiety combined with a variety of substituted phenyl rings, was synthesized and evaluated for antitumor activity. Results of the in vitro assay against a non-small cell lung carcinoma cell line (NCI-H460) showed several compounds to be endowed with cytotoxicity in micromolar to sub-micromolar range, depending on substitution pattern and position of aryl rings on 4,5-dihydropyrazole core. Potent and selective activity was also observed in the NCI 60 human cancer cell line panel. 5-(3,4,5-Trimethoxyphenyl)pyrazolines 31 and 39 were found to possess potent antiproliferative activity against SR and MDA-MB-435, with GI₅₀ inhibitory values in nanomolar range. Structure–activity relationships revealed that introduction of a (hydroxy)acetyl group at N-1 of inactive 5-(3,4,5-trimethoxyphenyl)pyrazolines, results in a clear in vitro activating effect. Compound 31 (IC₅₀ = 5.16 μM) showed inhibition of tubulin polymerization comparable to that of CA-4 (IC₅₀ = 4.92 μM).     

Biphenyl derivatives incorporating urea unit as novel VEGFR-2 inhibitors: Design,synthesis and biological evaluation

A series of novel biphenyl urea derivates were synthesized and investigated for their potential to inhibit vascular endothelial growth factor receptor-2 (VEGFR-2). In particular, A7, B3 and B4 displayed significant enzymatic inhibitory activities, with IC₅₀ values of 4.06, 4.55 and 5.26 nM. Compound A7 exhibited potent antiproliferative activity on several cell lines. SAR study suggested that the introduction of methyl at ortho-position of the biphenyl urea and tertiary amine moiety could improve VEGFR-2 inhibitory activity and antitumor effects. Molecular docking indicated that the urea moiety formed four hydrogen bonds with DFG residue. These biphenyl ureas could serve as promising lead compounds for further optimization.