Synthesis and cytotoxic evaluation of some new phthalazinylpiperazine derivatives

A new series of 1,4‐disubstituted phthalazinylpiperazine derivatives 7a–f , 12a–f and 20a–f were designed and synthesized in order to develop potent and selective antitumor agents. The target compounds were screened for their cytotoxic activities against A549, HT‐29 and MDA‐MB‐231 cancer cell lines in vitro. Among them, compounds 7a–f exhibited excellent selectivity for MDA‐MB‐231 with IC₅₀ values ranging from 0.013 µM to 0.079 µM. The most promising compound, 7e (IC₅₀ = 2.19 µM, 2.19 µM, 0.013 µM), was 9.3, 10, and 4.9 × 10³ times more active than vatalanib (IC₅₀ = 20.27 µM, 21.96 µM, 63.90 µM), respectively.     

Synthesis and anticancer activity of Indolin-2-one derivatives bearing the 4-thiazolidinone moiety

A novel series of indolin‐2‐one derivatives containing the 4‐thiazolidinone moiety ( 5a—5p ) was synthesized and the cytotoxicity of these derivatives was evaluated in vitro against three human cancer cell lines (HT‐29, H460 and MDA‐MB‐231) by standard MTT assay. Some prepared compounds exhibited significant cytotoxicity against different human cancer cell lines. Several potent compounds were further evaluated against one normal cell line (WI‐38). In particular, the promising compound 5h showed remarkable cytotoxicity and selectivity against the HT‐29 and H460 cancer cell lines (IC₅₀ = 0.016 µmol/L, 0.0037 µmol/L, respectively).     

The application of tandem aza-wittig reaction to synthesize artemisinin-guanidine hybrids and their anti-tumor activity

Three series of novel artemisinin–guanidine hybrids 4a–4f , 8a–8h and 9a–9h have been facilely synthesized via four‐component reaction (aza‐Wittig reaction) and evaluated for their anti‐tumor activities against A549, HT‐29 and MDA‐MB‐231 cell lines in vitro. All of the tested compounds showed enhanced anti‐tumor activities with IC₅₀ values ranging from 0.02 µM to 12.0 µM as compared to DHA (dihydroartemisinin). Among them, artemisinin derived dimers, compounds 9b (IC₅₀ = 0.05 µM), 9d (IC₅₀ = 0.06 µM) and 9f (IC₅₀ = 0.02 µM) were found to be most active against HT29 cells.     

Anti-tumor activity of new artemisinin-chalcone hybrids

In an attempt to develop potent and selective anti‐tumor agents, three new series of artemisinin–chalcone hybrids 10a – 10g , 11a – 11g and 12a–12h were designed, synthesized and screened for their anti‐tumor activity against five cell lines (HT‐29, A549, MDA‐MB‐231, HeLa and H460) in vitro. Among compounds 10a–g and 11a–11g , most of them displayed enhanced activity and good selectivity toward HT‐29 and HeLa cell lines with IC₅₀ values ranging from 0.12 to 0.85 µM as compared with DHA (dihydroartemisinin). Compounds 10a and 11a are most active toward HeLa cells with IC₅₀ values of 0.12 and 0.19 µM. The results revealed that the presence of chalcone moiety is beneficial to their activity and selectivity. In addition, compounds 12a ‐ 12h containing a ‘reversed chalcone’ moiety showed only slight improvement in activity than those of DHA.     

Synthesis and Biological Evaluation of Novel 6‐Hydrazinyl‐2,4‐bismorpholino pyrimidine and 1,3,5‐Triazine Derivatives as Potential Antitumor Agents

A series of 6‐hydrazinyl‐2,4‐bismorpholino pyrimidine and 1,3,5‐triazine derivatives ( 5a – 5l and 8a – 8o ) were synthesized and their chemical structures as well as the relative stereochemistry were confirmed. All the synthesized compounds were evaluated for antiproliferative activity against three cancer cell lines (H460, HT‐29, and MDA‐MB‐231). Several potent compounds were further evaluated against two other cell lines (U87MG, H1975). Most of the prepared compounds, particularly compounds 5c and 5j with IC₅₀ values (0.07 and 0.05 µM, respectively) in the nM range, exhibited moderate to excellent antiproliferative activity and high selectivity against the H460 cancer cell line as compared with compound 1 . The most promising compound 5j , possessing a cyano group at the 3‐position of the benzene ring, showed strong antiproliferative activity against H460, HT‐29, and MDA‐MB‐231 cell lines with IC₅₀ values of 0.05, 6.31, and 6.50 µM, which were 4.6‐ to 190.4‐fold more active than compound 1 (9.52, 29.24, and 36.21 µM), respectively.     

Design and synthesis of 2-iminothiazolidin-4-one moiety-containing compounds as potent antiproliferative agents

A new series of 2,5‐diaryliminothiazolidin‐4‐ones were designed and synthesized as potent antiproliferative agents. The antiproliferative activities of the 25 target compounds were evaluated against three cancer cell lines (A549, H460 and HT29) by MTT assay. Pharmacological data indicated that most of the compounds possessed moderate activity, some showed remarkable activity against one or more cell lines. As the most promising compound, 8s (with IC₅₀ values of 1.1, 0.01 and 1.3 µM against the A549, H460 and HT29 cell lines) was 1.1‐ to 270‐fold more potent than the reference drug sorafenib. Furthermore, preliminary structure–activity relationships (SARs) were summarized to provide guidance for further design and discovery of 2‐iminothiazolidin‐4‐one‐based antiproliferative agents.     

Design,Synthesis and Molecular Docking Studies of Novel Indole–Pyrimidine Hybrids as Tubulin Polymerization Inhibitors

A series of novel hybrids of indole–pyrimidine‐containing piperazine moiety were designed, synthesized and evaluated for their antiproliferative and tubulin polymerization inhibitory activities. The results indicated that most of these compounds possessed significant cytotoxic potency against four cancer cell lines, HT‐29, A549, MDA‐MB‐231 and MCF‐7. Particularly, the most promising compound 34 showed more potent and broad‐spectrum cytotoxic activities with the IC₅₀ values ranged from 5.01 to 14.36 μm against A549, MDA‐MB‐231 and MCF‐7 cell lines. Meanwhile, 34 also displayed the most potent tubulin polymerization inhibitory activity with IC₅₀ value of 11.2 μm . Furthermore, molecular docking analysis demonstrated 34 interacts and binds efficiently with the tubulin protein at the colchicine‐binding site. It was worth noting that the compound did not affect the normal human embryonic kidney cells, HEK‐293. These results suggest that this novel class of indole–pyrimidine hybrids may have potential to be developed as new a class of tubulin polymerization inhibitors.     

Synthesis and biological activities of 2-amino-thiazole-5-carboxylic acid phenylamide derivatives

In an attempt to develop potent and selective anti‐tumor drugs, a series of novel 2‐amino‐thiazole‐5‐carboxylic acid phenylamide derivatives were designed based on the structure of dasatinib. All compounds were synthesized by a systematic combinatorial chemical approach. Biological evaluation revealed that N‐(2‐chloro‐6‐methylphenyl)‐2‐(2‐(4‐methylpiperazin‐1‐yl)acetamido)thiazole‐5‐carboxamide ( 6d ) exhibited high antiproliferative potency on human K563 leukemia cells comparable to dasatinib. Against mammary and colon carcinoma cells 6d was either inactive (MDA‐MB 231) or distinctly less active (MCF‐7 and HT‐29: IC₅₀ = 20.2 and 21.6 µM, respectively). Dasatinib showed at each cell line IC₅₀ < 1 µM. The results of this structure activity relationship study clearly documented that the pyrimidin‐4‐ylamino core of dasatinib is responsible for the anti‐tumor activity against non‐leukemia cell lines.     

Synthesis,in‐vitro Cytotoxicity,and a Preliminary Structure‐Activity Relationship Investigation of Pyrimido[4,5‐c]quinolin‐1(2H)‐ones

As part of our ongoing research effort to develop new antimitotic agents based on the recently reported pyrimido[4,5‐c]quinoline‐1(2H)‐one ring skeleton, we were interested in identifying structural elements that contribute to the cytotoxicity of this class of compounds. The effect of several quinoline‐ring substituents was examined and the new compounds were evaluated in vitro for cytotoxicity against three human cancer cell lines namely, lung fibrosarcoma HT‐1080, colon adenocarcinoma HT‐29, and breast carcinoma MDA‐MB‐231. Most of the compounds showed cytotoxic activity in the low micromolar and sub‐micromolar range. Structure‐activity relationship information revealed that a combination of electronic and steric factors may be involved. Flow cytometric cell cycle analysis performed on HT‐1080 cells revealed that the most cytotoxic compounds 48 , 50 , 54 , 59 , and 63 inhibit the S‐phase and arrest the cells in the G2/M phase of the cell cycle suggesting an antimitotic action of these compounds.     

Exploration of imidazole and imidazopyridine dimers as anticancer agents: Design,synthesis, and structure–activity relationship study

Dimerization of proteins/receptors plays a critical role in various cellular processes, including cell proliferation and differentiation. Therefore, targeting such dimeric proteins/receptors by dimeric small molecules could be a potential therapeutic approach to treating various diseases, including inflammation‐associated diseases like cancer. A novel series of bis‐imidazoles ( 13–18 ) and bis‐imidazo[1,2‐a]pyridines ( 19–28 ) were designed and synthesized from Schiff base dimers ( 1–12 ) for their anticancer activities. All the synthesized compounds were screened for anticancer activities against three cancer cell lines, including cervical (HeLa), breast (MDA‐MB‐231), and renal cancer (ACHN). From structure–activity relationship studies, imidazo[1,2‐a]pyridines ( 19–28 ) showed remarkable cytotoxic activities, with compounds 19 and 24 showing the best inhibitory activities against all three cell lines. Especially, both 19 and 24 were very effective against the breast cancer cell line ( 19 , GI₅₀ = 0.43 µM; 24 , GI₅₀ = 0.3 µM), exceeding the activity of the control adriamycin (GI₅₀ = 0.51 µM). The in vivo anticancer activity results of compounds 19 and 24 were comparable with those of the animals treated with the standard drug tamoxifen. Therefore, the dimeric imidazo[1,2‐a]pyridine scaffold could serve as a potential lead for the development of novel anticancer agents.     

In-vitro antiproliferative activity of benzopyranone derivatives in comparison with standard chemotherapeutic drugs

The cytotoxic activities of five new benzopyranone derivatives containing basic amino side chain are described. Their cytotoxicities against ER(+) MCF‐7 and ER(–) MDA‐MB‐231 human breast cancer cell lines, and Ishikawa human endometrial cell line were determined after 72 h drug exposure employing CellTiter‐Glo assay at concentrations ranging from 0.01–1.0 × 10⁵ nM. The antiproliferative activities of these compounds were compared to tamoxifen (TAM), 4‐hydroxytamoxifen (4‐OHT, active metabolite of tamoxifen), and raloxifene (RAL). In‐vitro results indicated that compounds 9 , 10 , 12 , and 13 were more potent than TAM against the human breast cancer cell lines with IC₅₀ < 20 µM. The in‐silico structure–activity relationships of these compounds and their binding mode within the estrogen receptor (ER) binding site using AutoDock vina are discussed.     

Synthesis and antitumor activity of 2‐isocamphanyl thiosemicarbazone derivatives via ROS‐enhanced mitochondrial damage

A series of novel 2‐isocamphanyl thiosemicarbazone derivatives were synthesized and characterized by ¹H NMR, ¹³C NMR, and HRMS. In in vitro anticancer activity, most derivatives showed considerable cytotoxic activity against four cancer cell lines (RPMI‐8226, A549, MDA‐MB‐231, and HepG2 cancer cells) and showed low toxicity against human gastric mucosal cells (GES‐1). Among them, compound 4h exhibited excellent antitumor activity against the tested cancer cells with IC₅₀ values of 0.4, 1.1, 1.6, and 1.7 μM for MDA‐MB‐231, RPMI‐8226, A549, and HepG2, respectively. Further, mechanism studies indicated that compound 4h induced apoptosis in MDA‐MB‐231 cells through enhancing reactive oxygen species levels, inducing mitochondrial membrane potential decrease, and influencing the expression of Bax, Bcl‐2, caspase‐3, and caspase‐9.     

Novel quinazolin‐4(3H)‐one linked to 1,2,3‐triazoles: Synthesis and anticancer activity

In this work, a wide range of novel quinazolin‐4(3H)‐one linked to 1,2,3‐triazoles was designed, synthesized, and evaluated against a panel of three human breast (MDA‐MB‐231, MCF‐7, T‐47D), lung (A549), and prostate (PC3) cancer cell lines. Our results revealed that the anticancer activity of the synthesized compounds was selectively affected by the presence of methoxy group on the linker between quinazolinone and 1,2,3‐triazole moieties. According to the calculated IC₅₀ values, compounds 6q , 6w , and 6x showed good cytotoxicity against breast cancer cell lines even more effective than the reference drug, etoposide. Compounds 6q and 6u were found to be potent compounds against A549, non‐small‐cell lung cancer (NSCLC), comparing with erlotinib. Also, the morphological analysis by acridine orange/ethidium bromide double staining test and flow cytometry analysis indicated that potent compounds induced apoptosis in human cancer cell lines. Molecular docking studies were performed to clarify the inhibition mode of compounds 6g , 6u , 6w , and 6x over the EGFR active site. The most promising compounds, 6q and 6u , possessing 3‐methoxy group were well oriented to the gatekeeper hydrophobic pocket of EGFR active site and interact well with Ala719, Val702, and Leu820 through hydrophobic interaction.     

Synthesis and Cytotoxic Evaluation of 6‐(3‐Pyrazolylpropyl) Derivatives of 1,4‐Naphthohydroquinone‐1,4‐diacetate

Several new 6‐(3‐pyrazolylpropyl) derivatives of 1,4‐naphthohydroquinone‐1,4‐diacetate (NHQ‐DA) have been prepared by chemical modifications of the Diels–Alder adduct of α‐myrcene and 1,4‐benzoquinone. All these new compounds and precursors have been evaluated in vitro for their cytotoxicity against cultured human cancer cells of MB‐231 breast‐adeno carcinoma, A‐549 lung carcinoma, and HT‐29 colon carcinoma. GI₅₀ values ranged in and below the micromolar concentration level.     

Design, synthesis and cytotoxicity of novel chalcone analogs derived from 1-cyclohexylpyrrolidin-2-one and 2,3-dihydrobenzo[f]chromen-1-one

Two divergent series of novel chalcone analogs, one derived from 1‐cyclohexylpyrrolidin‐2‐one and the other derived from 1‐benzo[f]chromanone, were designed, synthesized and evaluated for cytotoxicity against two murine cancer cell lines. Two 1‐benzo[f]chromanone analogs, 4g and 4j yielded moderate toxicity against both melanoma B16 and lymphoma L1210 cell lines with IC₅₀ values between the range of 5 and 6 µM. With an IC₅₀ value of 3.4 µM, compound 4g was also active against human MDA‐MB‐435 melanoma cells. X‐ray structures of the β‐hydroxy ketone product ( 4a ) and the α,β‐unsaturated ketone ( 4h ) were collected, and confirm the syn‐configuration between the carbonyl moiety and the β‐vinylic proton in 4h . X‐ray structures of two 1‐cyclohexylpyrrolidin‐2‐one derivatives were also obtained, and both showed an E‐configuration for the double bond.     

Design,synthesis, and biological evaluation of novel 4‐phenoxypyridine derivatives as potential antitumor agents

A series of novel 4‐phenoxypyridine derivatives containing the 4‐oxo‐1,4‐dihydropyridazine‐3‐carboxamide moiety were synthesized and evaluated for their in vitro cytotoxic activity against the A549 cancer cell line, and some compounds were further examined for their cytotoxic activity against the H460, BGC823, MKN45, and HT‐29 cancer cell lines. Most of the compounds exhibited moderate to significant cytotoxicity. The most promising compound 15b (with VEGFR2 inhibitory concentration [IC₅₀] value of 0.23 μM) showed remarkable cytotoxicity against A549, BGC‐823, MKN45, H460, and HT‐29 cells, with IC₅₀ values of 0.75, 1.68, 2.63, 5.08 and 7.22 μM, respectively. Their preliminary structure‐activity relationship studies indicate that electron‐withdrawing groups on the terminal phenyl rings are beneficial for improving the antitumor activity. Moreover, treatment of A549 cells with compound 15b resulted in cell cycle arrest in the G₀/G₁ phase in a dose‐dependent manner. Further apoptotic studies and acridine orange/ethidium bromide staining were also performed on A549 cells, which showed that compound 15b could induce apoptosis. Wound‐healing assay results indicated that compound 15b strongly inhibited A549 cell motility.     

Design,synthesis, and molecular docking study of 3H‐imidazole[4,5‐c]pyridine derivatives as CDK2 inhibitors

A novel series of imidazo[4,5‐c]pyridine‐based CDK2 inhibitors were designed from the structure of CYC202 via scaffold hopping strategy. These compounds were synthesized and biologically evaluated for their CDK2 inhibitory and in vitro anti‐proliferation potential against cancer cell lines. Several compounds exhibited potent CDK2 inhibition with IC₅₀ values of less than 1 µM. The most potent compound 5b showed excellent CDK2 inhibitory (IC₅₀ = 21 nM) and in vitro anti‐proliferation activity against three different cell lines (HL60, A549, and HCT116). The molecular docking and dynamic studies portrayed the potential binding mechanism between 5b and CDK2, and several key interactions between them were observed, which would be the reason for its potent CDK2 inhibitory and anti‐proliferation activities. Therefore, the pyridin‐3‐ylmethyl moiety would serve as an excellent pharmacophore for the development of novel CDK2 inhibitors for targeted anti‐cancer therapy.

     

Synthesis and Biological Evaluation of Distamycin Analogues – New Potential Anticancer Agents

Eight of analogues of distamycin, potential minor‐groove binders, were synthesized and tested for in‐vitro cytotoxicity towards human breast cancer cells MCF‐7 and MDA‐MB‐231. The method of synthesis is simple and convenient. All of the compounds 1 – 8 showed antiproliferative and cytotoxic effects against both cell lines in the range 3.47 to 12.53 μM for MDA‐MB‐231 and 4.35 to 12.66 μM for MCF‐7. All compounds demonstrated activity against DNA topoisomerases I and II at a concentration of 50 μM. The ethidium bromide assay showed that these compounds bind to plasmid pBR322, yet weaker than distamycin. Further investigations concerning the mechanism of cytotoxicity are now in progress, but the IC₅₀ values suggest that synthetic distamycin analogues with a free amino group, 3 – 4 and 7 – 8 , can serve as potential carriers of strong acting elements, e. g. alkylating groups.     

Design,synthesis, and cytotoxic evaluation of novel scopoletin derivatives

A series of scopoletin derivatives were designed and synthesized by introducing α‐aminoacetamide, acrylamide and β‐aminopropamide, respectively, to 3‐position of scopoletin, and their chemical structures were confirmed by ESI‐MS, IR, ¹H NMR, and ¹³C NMR spectra. All target compounds were evaluated in vitro against four human cancer cell lines (MDA‐MB‐231, MCF‐7, HepG2, and A549) by MTT method. Cytotoxic assay showed that compounds 7a , 7b , 7e , 7f , 8a , and 8e exhibited more potent cytotoxicities compared to scopoletin. Besides, we have further evaluated the growth inhibitory activities of these selected compounds against normal tissue cell lines HFL‐1. Although compound 8a showed the strongest antiproliferative activity in vitro, it exhibited strong cytotoxicity on normal cells HFL‐1, which limited its further study. Compound 7a and 7b exhibited higher antiproliferative activity against MDA‐MB‐231 and HepG2 cells and weak cytotoxicity on HFL‐1, which suggested that 7a and 7b might be ideal anticancer candidates. The SARs showed that the introduction of the acrylamide and its analogues β‐aminopropamide could significantly improve activity, while the α‐aminoacetamide failed to enhance potency obviously. Therefore, the mechanism of compound 7a and 7b is worthy of further research and the structure of compound 8a should be further optimized.