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.     

Synthesis and cytotoxicity studies of novel 2-Hydrazonylpyrido[2,3-b]pyrazin-3(4H)-ones

In an attempt to develop potent antitumor agents, a series of novel 2‐hydrazonylpyrido[2,3‐b]pyrazin‐3(4H)‐one derivatives were designed and synthesized. All the prepared compounds were screened for their cytotoxic activities against A549, MDA‐MB‐231 and HT‐29 cell lines in vitro. Pharmacological data indicated that five of the target compounds showed cytotoxicity against A549 cell line below a concentration of 1 µM. Compound 15g was the most potent one with IC₅₀ values of 0.19, 2.11 and 2.15 µM against A549, MDA‐MB‐231 and HT29 cell lines, 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).     

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.     

Conjugation of Uridine with Oleanolic Acid Derivatives as Potential Antitumor Agents

According to fused two bioactive moieties together by bonds covalently and available as a new single hybrid entity known as pharmacophore hybridization, a total of 10 targeted uridine–oleanolic acid hybrids were synthesized. Most of these hybrids showed excellent proliferation inhibition against tested Hep‐G2, A549, BGC‐823, MCF‐7, and PC‐3 tumor cell lines (IC₅₀ < 8 μm ), even with some IC₅₀ values under 0.1 μm . The detection of cytotoxicity selectivity revealed that hybrids 5 and 18 exhibited low cytotoxicity toward normal human liver cell HL‐7702. Further studies revealed that selected hybrid 5 could induce apoptosis in Hep‐G2 cells through the investigation of acridine orange/ethidium bromide, Hoechst 33258 fluorescence stainings, and annexin V/propidium iodide assay. It was also found that hybrid 5 could induce mitochondrial membrane potential disruption, arrest Hep‐G2 cell line at G1 phase, and activate effector caspase‐3/9 to trigger cell apoptosis.     

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.     

Click chemistry‐based synthesis and cytotoxic activity evaluation of 4α‐triazole acetate podophyllotoxin derivatives

A series of novel 4α‐triazole acetate podophyllotoxin derivatives were synthesized via click chemistry. In vitro cytotoxic activity evaluation showed that most of the derivatives exhibited potent inhibitory activities against the tested cancer cell lines with low nanomolar IC₅₀ values. Further studies demonstrated that compound 31 exhibited broad‐spectrum cytotoxic activities, effectively overcame drug‐resistance, and showed relatively weak cytotoxicity on non‐cancer cells. Preliminary mechanistic studies indicated that 31 might have action on microtubule, cause cell cycle arrest at G₂/M phase, and induce apoptosis in human PC‐3 cancer cells.     

Design,synthesis, and evaluation of the anticancer activity of 2‐amino‐aryl‐7‐aryl‐benzoxazole compounds

A series of 2‐amino‐aryl‐7‐aryl‐benzoxazole derivatives have been designed, synthesized, and evaluated as anticancer agents. Fourteen of the compounds exhibited cytotoxic effects toward human A549 lung cancer cells. We found 12l was the most potent with an EC₅₀ of 0.4 μm , equivalent to the anticancer drug doxorubicin, but had low selectivity following cross screening in monkey kidney Vero cells. Eight of the most potent or most selective compounds were further profiled in additional cell lines (MCF7, NCI‐H187, and KB) to better understand their cytotoxic activity. Only compound 12l had a measurable EC₅₀ in a single cell line (3.3 μm in the KB cell line). Taken together, this data suggest the series as a whole display specific cytotoxicity toward A549 cells. Cheminformatics searches pointed to JAK2 as a possible target. A subset of compounds assayed at this target showed IC₅₀s ranging from 10 to 0.08 μm ; however, no clear correlation between JAK2 potency and A549 cytotoxicity was observed.     

Synthesis of new arylisoxazole–oxindole conjugates as potent antiproliferative agents

A new series of arylisoxazole–oxindole derivatives ( 6a–r ) were synthesized and evaluated for their antiproliferative activity against human cancer cell lines including non‐small cell lung (A549), cervical (HeLa), breast (MCF‐7), and prostate (DU‐145) cancer cell lines. The synthesized compounds ( 6a–r ) demonstrated excellent to moderate cytotoxicity with IC₅₀ values ranging from 0.82 to 3.69 μm . Some new compounds ( 6m–r ) exhibited profound cytotoxicity better or similar to positive control. More particularly, the compound 6q possesses donating substituent like methoxy group presented at 5‐position on D ring exhibited remarkable antiproliferative activity against A‐549 (lung cancer) with an IC₅₀ value 0.82 μm . Further studies to determine the mechanistic aspects of these conjugates are under progress.     

Synthesis and cytotoxic activity of two steroids: icogenin aglycone analogs

During the process of icogenin analog research, we obtained two cytotoxic steroids: compound 4 and compound 6 casually. Their in vitro antitumor activities were tested by the standard MTT assay. The results disclosed that compound 4 (IC₅₀ = 3.65–6.90 μM) showed potential antitumor activities against HELA, KB cell lines and compound 6 (IC₅₀ = 2.40–9.05 μM) showed potential antitumor activities against HELA, BGC-823, KB, A549, HCT-8 cell lines.     

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 cytotoxicity evaluation of novel podophyllotoxin derivatives

Seven benzylamino derivatives of podophyllotoxin 8a–8g were synthesized and their chemical structures were confirmed by IR, ¹H‐NMR, ¹³C‐NMR and ESI‐MS spectral analyses. Their abilities to inhibit the growth of cancer cells A549, HCT‐116 and HepG2, were investigated by MTT assay. Compound 8b possessed the highest cytotoxicity on cancer cell lines with average IC₅₀ values of 3.8 µM. All we synthetic compounds were cytotoxic against three cancer cell lines at the micromolar range, indicating podophyllotoxin derivatives with structural modification of benzylamino possess potent antitumor activity.     

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.     

Cytotoxic Activity and Three-Dimensional Quantitative Structure Activity Relationship of 2-Aryl-1,8-naphthyridin-4-ones

A series of substituted 2-arylnaphthyridin-4-one analogues, which were previously synthesized in our laboratory, were evaluated for their in vitro cytotoxic activity against human lung cancer A549 and human renal cancer Caki-2 cells using MTT assay. Some compounds (11, 12, and 13) showed stronger cytotoxicity than colchicine against both tumor cell lines, and compound 13 exhibited the most potent activity with IC₅₀ values of 2.3 and 13.4 µM, respectively. Three-dimensional quantitative structure activity relationship (3D-QSAR) studies of comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed. Predictive 3D-QSAR models were obtained with q² values of 0.869 and 0.872 and r²_ncv values of 0.983 and 0.993 for CoMFA and CoMSIA, respectively. These results demonstrate that CoMFA and CoMSIA models could be reliably used in the design of novel cytotoxic agents.     

Synthesis and Evaluation of Salicylanilide Derivatives as Potential Epidermal Growth Factor Receptor Inhibitors

Two series of novel salicylanilide were synthesized as potential epidermal growth factor receptor (EGFR) inhibitors. The enzyme inhibitory activity against EGFR of all compounds was carried out, and their antiproliferative activities against the A549 and A431 cell lines were also evaluated. Of the compounds studied, majority of them exhibited high antiproliferative activities compared with gefitinib; especially, 12a and 12b exhibited stronger inhibitory activity against EGFR with IC₅₀ values of 10.4 ± 2.25 and 15.4 ± 2.33 nm , respectively, which were comparable to the positive control of gefitinib (IC₅₀ = 12.1 ± 2.21 nm ). Compound 12b also showed outstanding inhibitory activity against A431 and A549 cell lines with the IC₅₀ values of 0.42 ± 0.43 μm and 0.57 ± 0.43 μm , which was better than the positive controls. In the molecular modeling study, compound 12b was bound into the active pocket of EGFR with two hydrogen bond and with minimum binding free energy ▵G_b = −25.1125 kcal/mol. The result also suggested that compound 12b could bind the EGFR kinase well.     

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.     

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.     

A new bis-γ-pyrone polypropionate from a marine pulmonate mollusc Onchidium struma

A new bis-γ-pyrone polypropionate compound onchidione II (1), together with three known compounds, was isolated from a marine pulmonate mollusc Onchidium struma, collected at Hainan Island of China. The structure of new compound was determined by extensive spectroscopic analyses including IR, 1D and 2D NMR techniques, and chemical methods. Compounds 1–4 were evaluated for their cytotoxicity against human tumor cell lines HepG-2, A549, and MCF-2. The results showed that compounds 1 and 2 were moderate cytotoxic against HepG-2, A549, and MCF-2 cell lines, with IC₅₀ values from 13.2 to 22.4 μM.     

Synthesis and in‐vitro Cytotoxicity of Poly‐functionalized 4‐(2‐Arylthiazol‐4‐yl)‐4H‐chromenes

A new series of 4‐aryl‐4H‐chromenes bearing a 2‐arylthiazol‐4‐yl moiety at the 4‐position were prepared as potential cytotoxic agents. The in‐vitro cytotoxic activity of the synthesized 4‐aryl‐4H‐chromenes was investigated in comparison with etoposide, a well‐known anticancer drug, using MTT colorimetric assay. Among them, the 2‐(2‐chlorophenyl)thiazol‐4‐yl analog 4b showed the most potent activity against nasopharyngeal epidermoid carcinoma KB, medulloblastoma DAOY, and astrocytoma 1321N1, and compound 4d bearing a 2‐(4‐chlorophenyl)thiazol‐4‐yl moiety at the 4‐position of the chromene ring exhibited the best inhibitory activity against breast cancer cells MCF‐7, lung cancer cells A549, and colon adenocarcinoma cells SW480 with IC₅₀ values less than 5 μM. The ability of compound 4b to induce apoptosis was confirmed in a nuclear morphological assay by DAPI staining in the KB and MCF‐7 cells.     

Synthesis of novel spin-labeled podophyllotoxin derivatives as potential antineoplastic agents: Part XXV

A series of novel spin-labeled 4β-[(4-substituted)-1,2,3-triazol-1-yl]podophyllotoxin derivatives (17a–h) were firstly designed and synthesized with significant regioselectivity by employing Cu(I) catalyzed click approach, and evaluated for cytotoxicity against four human tumor cell lines (A-549, DU145, KB, and KBvin). Among them, compound 17h displayed the highest cytotoxic activity against the tumor cell lines tested. Significantly, compound 17h showed superior cytotoxic activity compared with etoposide (IC₅₀ 6.30 to >10 μM), a clinically available anticancer drug. Significant activity toward the drug resistant KBvin cell line revealed promising future for compound 17h as a new generation of epipodophyllotoxin-derived antitumor clinical trial candidate.