Synthetic strategy for increasing solubility of potential FLT3 inhibitor thieno[2,3-d]pyrimidine derivatives through structural modifications at the C2 and C6 positions

Acute myeloid leukemia (AML) is a clonal disorder of hematopoietic progenitor cell. In AML, a mutation in FLT3 is commonly occurs and is associated with poor prognosis. We have previously reported that thieno[2,3-d]pyrimidine derivative compound 1 exhibited better antiproliferative activity against MV4-11 cells which harbor mutant FLT3 than AC220, which is a well-known FLT3 inhibitor, and has good microsomal stability. However, compound 1 had poor solubility. We then carried out further structural modification at the C₂ and the C₆ positions of thieno[2,3-d]pyrimidine scaffold. Compound 13b, which possesses a thiazole moiety at the C₂ position, exhibited better antiproliferative activity than compound 1 and showed increased solubility and moderate microsomal stability. These results indicate that compound 13b could be a promising potential FLT inhibitor for AML chemotherapy.     

Discovery of novel 4(1H)-quinolone derivatives as potential antiproliferative and apoptosis inducing agents

A series of novel 4(1H)-quinolone derivatives was synthesized and evaluated for antiproliferative activity in vitro. The results showed that these compounds exhibited more potent antiproliferative effect against a panel of human tumor cell lines than the lead compound 7-chloro-4(1H)-quinolone 1. Compound 7e was found to be the most potent antiproliferative agent and to exhibit selective cytotoxic activity against HepG2 cell lines with IC₅₀ value lower than 1.0 μM. Annexin V/FITC-PI assay showed that compound 7e induced apoptosis in HepG2 cells with a dose-dependent manner. Western blotting analysis indicated that compound 7e induced cell cycle arrest in G2/M phase by p53-depedent pathway.     

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.     

Design and synthesis of novel dasatinib derivatives as inhibitors of leukemia stem cells

We used the concept of bioisosteres to design and synthesize a novel series of dasatinib derivatives for the treatment of leukemia. Unfortunately, most of the dasatinib derivatives did not show appreciable inhibition against leukemia cell lines K562 and HL60. However, acrylamide compound 2c had comparable inhibitory activity with dasatinib against K562 cells (IC₅₀?=?0.039?nM vs. 0.069?nM). And amide compound 2a and acrylamide compound 2c also had comparable inhibitory activity with dasatinib against the leukemia cell line HL60 (IC₅₀?=?0.25?nM and 0.26?nM vs. 0.11?nM). Against the leukemia progenitor cell line KG1a, triazole compounds 15a and 15d–15f and oxadiazole compounds 24a–24d were more potent than dasatinib. In particular, the hydroxyl compounds 15a and 24a were about 64 and 180 fold more potent than dasatinib against KG1a cells (IC₅₀?=?0.14?μM and 0.05?μM vs. 8.98?μM). Compounds 15a and 24a also inhibited colony formation in MCF-7 cells and inhibited cell migration in the cell wound scratch assay in B16BL6 cells. Moreover, hydroxyl compounds 15a and 24a had low toxicity in vivo.     

Discovery of novel chalcone-dithiocarbamates as ROS-mediated apoptosis inducers by inhibiting catalase

Novel chalcone-dithiocarbamate hybrids were designed, synthesized and evaluated for antiproliferative activity against selected cancer cell lines (MGC803, MCF7, and PC3). Among these analogues, (E)-2-oxo-2-((4-(3-(3,4,5-trimethoxyphenyl)acryloyl)phenyl)amino)ethyl-4-(2-hydroxyethyl)piperazine-1-carbodithioate (12d) showed the best inhibitory activity against PC3 cells (IC₅₀ = 1.05 μM). Cellular mechanism studies elucidated 12d could inhibit colony formation, arrest cell cycle at G2/M phase and induce DNA damage against PC3 cells. Compound 12d also induced mitochondrial apoptosis by caspase activation, MMP decrease, ROS production and catalase (CAT) inhibition. Importantly, 12d inhibited epithelial-mesenchymal transition (EMT) process by regulating EMT-related proteins (E-cadherin, N-cadherin, Vimentin, MMP2, MMP9). These results indicated that 12d is a promising lead compound and deserves further investigation for prevention and treatment of human prostate cancer.     

Design,synthesis, and biological evaluation of novel aminopyrimidinylisoindolines as AXL kinase inhibitors

A novel series of aminopyrimidinylisoindoline derivatives 1a-w having an aminopyrimidine scaffold as a hinge region binding motif were designed and synthesized. Among them, six compounds showed potent inhibitory activities against AXL kinase with IC₅₀ values of submicromolar range. Especially, compound 1u possessing (4-acetylpiperazin-1-yl)phenyl moiety exhibited extremely excellent efficacy (IC₅₀?=?<0.00050?μM). Their in vitro antiproliferative activities were tested over five cancer cell lines. Most compounds showed good antiproliferative activities against HeLa cell line. The kinase panel profiling of 50 different kinases and the selected inhibitory activities for the representative compound 1u were carried out. The compound 1u exhibited excellent inhibitory activities (IC₅₀?=?<0.00050, 0.025, and 0.050?μM for AXL, MER, and TYRO3, respectively) against TAM family, together with potent antiproliferative activity against MV4-11 cell line (GI₅₀?=?0.10?μM) related to acute myeloid leukemia (AML).     

Novel synthetic 2-amino-10-(3,5-dimethoxy)benzyl-9(10H)-acridinone derivatives as potent DNA-binding antiproliferative agents

A series of novel 9(10H)-acridinone derivatives with terminal amino substituents at C2 position on the acridinone ring were synthesized and studied for their antiproliferative activity and underlying mechanisms. These compounds demonstrated promising cytotoxicity to leukemia cells CCRF-CEM, displaying IC₅₀ values in the low micromolar range. Structure–activity relationships (SAR) indicated that the compound 6d bearing a pyrrolidine substituent and 8a with a methyl ammonium side chain displayed higher cytotoxicity to CCRF-CEM cells and also solid tumor cells A549, HepG2, and MCF7. Furthermore, the compounds 6d and 8a had strong binding activity to calf thymus DNA (ct DNA), as detected by UV absorption and fluorescence quenching assays, but limited inhibitory activity to human topoisomerase 1 (topo 1). Taken together, this study discovered a series of new synthetic 9(10H)-acridinone derivatives with potent DNA binding and anticancer activity.     

Design,synthesis and antiproliferative activity of novel substituted 2-amino-7,8-dihydropteridin-6(5H)-one derivatives

Based on our previous work, a series of novel 2-amino-7,8-dihydropteridin-6(5H)-one derivatives were designed and synthesized via a ring-closing strategy. Biological evaluation with four human cancer cell lines (BT549, T47D, MDA-MB-468, and MDA-MB-231) showed that most of these compounds possessed moderate to potent antiproliferative activities. The most promising compound 8-benzyl-2-(phenethylamino)-7,8-dihydropteridin-6(5H)-one (6q) possessing IC₅₀ values of 7.75, 6.37, and 10.73 μM against MDA-MB-468, T47D, and BT549, respectively, which were 49, 11, and 8 folds more active than the positive control fluorouracil. Moreover, fluorescence-activated cell sorting analysis revealed that compound 6q displayed a significant effect on G1 cell-cycle arrest in a concentration-dependent manner in T47D cells. The initial structure–activity relationship studies indicated that linker-length of amine chain in C-2 position of pyrimidine ring played a crucial role in modulating the antitumor activity, which could be of help in the rational design of dihydropteridin-6(5H)-ones as novel anticancer drugs.     

Antiproliferative metabolites from the endophytic fungus Penicillium sp. FJ-1 isolated from a mangrove Avicennia marina

Two new compounds, named as 4-(2′,3′-dihydroxy-3′-methyl-butanoxy)-phenethanol (1), and 15-hydroxy-6α,12-epoxy-7β,10αH,11βH-spiroax-4-ene-12-one (2), were isolated from the endophytic fungus Penicillium sp.FJ-1 of Avicennia marina. Their structures were elucidated on the basis of spectroscopic analysis. Additionally, compounds 1 and 2 exhibited antiproliferative activities, and compound 2 significantly inhibited the tumor growth of human xenograft osteosarcoma in nude mice.     

Synthesis and neuroprotective effect of E-3,4-dihydroxy styryl aralkyl ketones derivatives against oxidative stress and inflammation

E-3,4-Dihydroxy styryl aralkyl ketones as well as their 3,4-diacetylated derivatives as the analogues of neuroprotective agent CAPE were designed and synthesized for improving stability and lipid solubility. The neuroprotective activities of target compounds 10a–g and 11a–g were tested by three models in vitro, including 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity, neuronal protecting effect against damage induced by H₂O₂ in PC12 cells and nitric oxide suppression effect in BV2 microglial cells. The results demonstrated that compounds 10f and 11f exhibited the most potent neuroprotective effect against oxidative stress and inflammation, which is higher than that of the lead compound CAPE.     

Synthesis and biological evaluation of 2-substituted-4-(3′,4′,5′-trimethoxyphenyl)-5-aryl thiazoles as anticancer agents

Antitumor agents that bind to tubulin and disrupt microtubule dynamics have attracted considerable attention in the last few years. To extend our knowledge of the thiazole ring as a suitable mimic for the cis-olefin present in combretastatin A-4, we fixed the 3,4,5-trimethoxyphenyl at the C4-position of the thiazole core. We found that the substituents at the C2- and C5-positions had a profound effect on antiproliferative activity. Comparing compounds with the same substituents at the C5-position of the thiazole ring, the moiety at the C2-position influenced antiproliferative activities, with the order of potency being NHCH₃ > Me ? N(CH₃)₂. The N-methylamino substituent significantly improved antiproliferative activity on MCF-7 cells with respect to C2-amino counterparts. Increasing steric bulk at the C2-position from N-methylamino to N,N-dimethylamino caused a 1–2 log decrease in activity. The 2-N-methylamino thiazole derivatives 3b, 3d and 3e were the most active compounds as antiproliferative agents, with IC₅₀ values from low micromolar to single digit nanomolar, and, in addition, they are also active on multidrug-resistant cell lines over-expressing P-glycoprotein. Antiproliferative activity was probably caused by the compounds binding to the colchicines site of tubulin polymerization and disrupting microtubule dynamics. Moreover, the most active compound 3e induced apoptosis through the activation of caspase-2, -3 and -8, but 3e did not cause mitochondrial depolarization.     

Natural product inspired allicin analogs as novel anti-cancer agents

A series of novel analogs of Allicin (S-allyl prop-2-ene-1-sulfinothioate) present in garlic has been synthesized in high yield. Synthesized 23 compounds were evaluated against different breast cancer cells (MDA-MB-468 and MCF-7) and non-cancer cells (WI38). Four compounds (3f, 3h, 3m and 3u) showed significant cytotoxicity against cancer cells whereas nontoxic to the normal cells. Based on the LD₅₀ values and selectivity index (SI), compound 3h (S-p-methoxybenzyl (p-methoxyphenyl)methanesulfinothioate) was considered as most promising anticancer agent amongst the above three compounds. Further bio-chemical studies confirmed that compound 3h promotes ROS generation, changes in mitochondrial permeability transition and induced caspase mediated DNA damage and apoptosis.     

4-(1H-Imidazo[4,5-f]-1,10-phenanthrolin-2-yl)phenol-based G-quadruplex DNA binding agents: Telomerase inhibition,cytotoxicity and DNA-binding studies

Four novel 4-(1H-imidazo[4,5-f]-1,10-phenanthrolin-2-yl)phenol derivatives 1–4 have been synthesized, and their G-quadruplex DNA-binding interactions, telomerase inhibition, antiproliferative activity, cell cycle arrest, and apoptotic induction were studied. All compounds show the preferential h-telo, c-myc, and c-kit2 G-quadruplex binding affinity and the G-quadruplex versus duplex selectivity. In the case of the same G-quadruplex target, the compound 1 exhibits better stabilization effect (ΔT_m) than the other three compounds and also gives 80.2% inhibition of telomerase activity at 7.5 μM. All compounds can promote selectively the formation of parallel G-quadruplex structure of both c-myc and c-kit2 without addition of any cations. Four compounds display the cytotoxicity activities against HeLa and HepG2 cells by MTT assay with IC₅₀ values of about 10^?6 and 10^?5 M, respectively, and cause a substantial decrease in the G₂/M-phase cell population and a significant increase in the number of apoptotic cells.     

Discovery of novel 4-aryl-thieno[1,4]diazepin-2-one derivatives targeting multiple protein kinases as anticancer agents

A series of 4-aryl-thieno[1,4]diazepin-2-one were synthesized and evaluated for their antiproliferative activities against the A375P melanoma and U937 hematopoietic cell lines. Several compounds showed very potent antiproliferative activities toward both cell lines and the activities were better than that of sorafenib, the reference standard. Derivatives were made as amide (8a–8i, 9a–9m) and urea (10a–10d, 11a–11d) with diverse hydrophobic moieties. One of the most potent inhibitor 10d, 1-(4-((4-ethylpiperazin-1-yl)methyl)-3-(trifluoromethyl)phenyl)-3-(4-(2-oxo-2,3-dihydro-1H-thieno [3,4-b][1,4]diazepin-4-yl)phenyl)urea was found to be very potent inhibitor of multi-protein kinases including FMS kinase (IC₅₀?=?3.73?nM) and is a promising candidate for further development in therapeutics for cancer.     

Synthesis,structure elucidation and in vitro anticancer activities of novel derivatives of diethyl (2E)-2-[(2E)-(1-arylimidazolidin-2-ylidene)hydrazono]succinate and ethyl (4-oxo-8-aryl-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl)acetate

The worked out and optimized synthesis routes and remarkable antitumour activities in vitro of novel polynitrogenated derivatives of diethyl (2E)-2-[(2E)-(1-arylimidazolidin-2-ylidene)hydrazono]succinate (7–10) and ethyl (4-oxo-8-aryl-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl)acetate (11–16) are presented. Small molecules based on the privileged 7,8-dihydroimidazo[2,1-c][1,2,4]triazin-4(6H)-one scaffold (11–16) were obtained with fairly modest to good overall yields by very facile addition reactions of the nucleophilic centred 1-aryl-2-hydrazonoimidazolidine hydroiodides to diethyl acetylenedicarboxylate (DEAD) in the presence of triethylamine (TEA) and a subsequent cyclocondensation of the putative intermediate chain hydrazones. Heterobicyclic products 12 and 14–16 could also be prepared in high overall yields by an effective intramolecular cyclocondensation of the isolated stable and antiproliferative active heterocyclic hydrazones, namely, diethyl (2E)-2-[(2E)-(1-arylimidazolidin-2-ylidene)hydrazono]succinates (7–10), performed in refluxing DMF. These intermediates are the first products to be formed in the result of an addition of the nucleophilic reactants, namely, 1-aryl-2-hydrazonoimidazolidines of the 1–6 type, bearing the basic nitrogen atom of the hydrazono moiety (N–NH₂), to the carbon–carbon triple bond of the highly electrophilic alkyne, that is, DEAD. Molecular structures of the synthesized compounds (7–16) in the DMSO-d₆ solutions were verified by ¹H NMR and ¹³C NMR spectral data. These were finally confirmed based on the advanced 2D HMBC and HMQC NMR experiments, which were performed for the two representatives (8 and 11) of the two synthesized sets of the bioactive substances. Among the majority of antiproliferative active molecules, the disclosed herein ethyl [4-oxo-8-(3-chlorophenyl)-4,6,7,8-tetrahydroimidazo[2,1-c][1,2,4]triazin-3-yl]acetate (14) is proposed as a promising lead structure for the design of novel highly selective antitumour agents because of the distinctly marked lower cytotoxicity towards the primary cell line of normal HSF cells and several-fold higher against cancer cells used. A double fluorochrome mix-staining was performed in order to find out about the possible mode of action by which this novel small heterobicycle reveals remarkable antiproliferative effects in vitro. Taking into account the obtained double staining results, this small molecule was identified as capable of inducing significantly higher levels of necrotic cells in human cancer cell lines (T47D and HeLa) than in normal HSF cells. Furthermore, its cytotoxicity against cells was found to be connected to the predominant induction of necrosis over apoptosis.     

Design and synthesis of new triazoles linked to xanthotoxin for potent and highly selective anti-gastric cancer agents

Two series of xanthotoxin-triazole derivatives were designed, synthesized, and studied for their antiproliferative properties. The in vitro cytotoxicity of the compounds in the AGS cancer cell line and the L02 normal cell line was evaluated via MTT assay. Among the synthesized compounds, 9-((1-(4-(trifluoromethyl)phenyl)-1H-1,2,3-triazol-4-yl)methoxy)-7H-furo[3,2-g]chromen-7-one (6p) was found to have the greatest antiproliferative activity against AGS cells (IC₅₀ = 7.5 μM) and showed better activity than the lead compound (xanthotoxin, IC₅₀ > 100 μM) and the reference drug (5-fluorouracil, IC₅₀ = 29.6 μM) did. The IC₅₀ value of 6p in L02 cells was 13.3 times higher than that in the AGS cells. Therefore, the compound exhibited better therapeutic activity and specificity compared with the positive control 5-fluorouracil. Cell cycle analysis revealed that compound 6p inhibited cell growth via the induction of S/G2 phase arrest in AGS cells. Compound 6p was identified as a promising lead compound for the further development and identification of 1,2,3-triazole-based anticancer agents.     

Discovery of N-aryl-9-oxo-9H-fluorene-1-carboxamides as a new series of apoptosis inducers using a cell- and caspase-based high-throughput screening assay. 1. Structure–activity relationships of the carboxamide group

N-(2-Methylphenyl)-9-oxo-9H-fluorene-1-carboxamide (2a) was identified as a novel apoptosis inducer through our caspase- and cell-based high-throughput screening assay. Compound 2a was found to be active with sub-micromolar potencies for both caspase induction and growth inhibition in T47D human breast cancer, HCT116 human colon cancer, and SNU398 hepatocellular carcinoma cancer cells. It arrested HCT116 cells in G₂/M followed by apoptosis as assayed by the flow cytometry. Structure–activity relationship (SAR) studies of the carboxamide group identified the lead compound N-(2-(1H-pyrazol-1-yl)phenyl)-9-oxo-9H-fluorene-1-carboxamide (6s). Compound 6s, with increased aqueous solubility, was found to retain the broad activity in the caspase activation assay and in the cell growth inhibition assay with sub-micromolar EC₅₀ and GI₅₀ values in T47D, HCT116, and SNU398 cells, respectively.     

Design and synthesis of novel nitrogen mustard-evodiamine hybrids with selective antiproliferative activity

A series of novel nitrogen mustard-evodiamine hybrids were synthesized and evaluated for their antitproliferative properties. The antiproliferative activities of 10a–d, 11a–d, and 12a–d against four different kinds of human cancer cell lines (PC-3, HepG2, THP-1 and HL-60) and human normal peripheral blood mononuclear cells (PBMC) were determined. The results showed that all the target hybrid compounds exhibited antiproliferative activities against tested human tumor cell lines to some extent and no antiproliferative activities (>200?μM) against human normal PBMC cells. The antiproliferative selectivity between tumorous and normal cells was very useful for further antitumor drug development. Among the target compounds, 12c showed the strongest cytotoxicity against two tumor cell lines (THP-1 and HL-60) with IC₅₀ values of 4.05?μM and 0.50?μM, respectively, and selected for further mechanism study in HL-60 cells. The results showed that 12c could induce HL-60 cells apoptosis and arrest at G₂ phase at low sub-micromolar concentrations via mitochondria-related pathways.     

Novel 5,6-disubstituted pyrrolo[2,3-d]pyrimidine derivatives as broad spectrum antiproliferative agents: Synthesis,cell based assays,kinase profile and molecular docking study

Two new series of 5-subtituted and 5,6-disubstituted pyrrolo[2,3-d]pyrimidine octamides (4a–o and 6a–g) and their corresponding free amines 5a–m and 7a–g have been synthesized and biologically evaluated for their antiproliferative activity against three human cancer cell lines. The 5,6-disubstituted octamides 6d–g as well as the amine derivative 7b have shown the best anticancer activity with single digit micromolar GI₅₀ values over the tested cancer cells, and low cytotoxic effects (GI₅₀?>?10.0?µM) against HFF-1 normal cell. A structure activity relationship (SAR) study has been established and disclosed that terminal octamide moiety at C2 as well as disubstitution with fluorobenzyl piperazines at C5 and C6 of pyrrolo[2,3-d]pyrimidine are the key structural features prerequisite for best antiproliferative activity. Moreover, the most active member 6f was tested for its antiproliferative activity over a panel of 60 cancer cell lines at NCI, and exhibited distinct broad spectrum anticancer activity with submicromolar GI₅₀ and TGI values over multiple cancer cells. Kinase profile of compound 6f over 53 oncogenic kinases at 10?µM concentration showed its highly selective inhibitory activity towards FGFR4, Tie2 and TrkA kinases. The observed activity of 6f against TrkA (IC₅₀?=?2.25?µM), FGFR4 (IC₅₀?=?6.71?µM) and Tie2 (IC₅₀?=?6.84?µM) was explained by molecular docking study, which also proposed that 6f may be a type III kinase inhibitor, binding to an allosteric site rather than kinase hinge region. Overall, compound 6f may serve as a promising anticancer lead compound that could be further optimized for development of potent anticancer agents.