Dual Parasiticidal Activities of Phthalimides: Synthesis and Biological Profile against Trypanosoma cruzi and Plasmodium falciparum

Chagas disease and malaria are two neglected tropical diseases (NTDs) that prevail in tropical and subtropical regions in 149 countries. Chagas is also present in Europe, the US and Australia due to immigration of asymptomatic infected individuals. In the absence of an effective vaccine, the control of both diseases relies on chemotherapy. However, the emergence of parasite drug resistance is rendering currently available drugs obsolete. Hence, it is crucial to develop new molecules. Phthalimides, thiosemicarbazones, and 1,3-thiazoles have been used as scaffolds to obtain antiplasmodial and anti-Trypanosoma cruzi agents. Herein we present the synthesis of 24 phthalimido-thiosemicarbazones ( 3 a – x ) and 14 phthalimido-thiazoles ( 4 a – n ) and the corresponding biological activity against T. cruzi, Plasmodium falciparum, and cytotoxicity against mammalian cell lines. Some of these compounds showed potent inhibition of T. cruzi at low cytotoxic concentrations in RAW 264.7 cells. The most active compounds, 3 t (IC₅₀=3.60 μM), 3 h (IC₅₀=3.75 μM), and 4 j (IC₅₀=4.48 μM), were more active than the control drug benznidazole (IC₅₀=14.6 μM). Overall, the phthalimido-thiosemicarbazone derivatives were more potent than phthalimido-thiazole derivatives against T. cruzi. Flow cytometry assay data showed that compound 4 j was able to induce necrosis and apoptosis in trypomastigotes. Analysis by scanning electron microscopy showed that T. cruzi trypomastigote cells treated with compounds 3 h , 3 t , and 4 j at IC₅₀ concentrations promoted changes in the shape, flagella, and surface of the parasite body similar to those observed in benznidazole-treated cells. The compounds with the highest antimalarial activity were the phthalimido-thiazoles 4 l (IC₅₀=1.2 μM), 4 m (IC₅₀=1.7 μM), and 4 n (IC₅₀=2.4 μM). Together, these data revealed that phthalimido derivatives possess a dual antiparasitic profile with potential effects against T. cruzi and lead-like characteristics.     

Pyrazoloadenine Inhibitors of the RET Lung Cancer Oncoprotein Discovered by a Fragment Optimization Approach

A fragment-based drug-discovery approach was used on a pyrazoloadenine fragment library to uncover new molecules that target the RET (REarranged during Transfection) oncoprotein, which is a driver oncoprotein in ∼2 % of non-small-cell lung cancers. The fragment library was screened against the RET kinase and LC-2/ad (RET-driven), KM-12 (TRKA-driven matched control) and A549 (cytotoxic control) cells to identify selective scaffolds that could inhibit RET-driven growth. An unsubstituted pyrazoloadenine fragment was found to be active on RET in a biochemical assay, but reduced cell viability in non-RET-driven cell lines (EC₅₀=1 and 3 μM, respectively). To increase selectivity for RET, the pyrazoloadenine was modeled in the RET active site, and two domains were identified that were probed with pyrazoloadenine fragment derivatives to improve RET affinity. Scaffolds at each domain were merged to generate a novel lead compound, 8 p , which exhibited improved activity and selectivity for the RET oncoprotein (A549 EC₅₀=5.92 μM, LC-2/ad EC₅₀=0.016 μM, RET IC₅₀=0.000326 μM).     

Design and Synthesis of Aminostilbene–Arylpropenones as Tubulin Polymerization Inhibitors

A series of aminostilbene—arylpropenones were designed and synthesized by Michael addition and were investigated for their cytotoxic activity against various human cancer cell lines. Some of the investigated compounds exhibited significant antiproliferative activity against a panel of 60 human cancer cell lines of the US National Cancer Institute, with 50 % growth inhibition (GI₅₀) values in the range from <0.01 to 19.9 μM . One of the compounds showed a broad spectrum of antiproliferative efficacy on most of the cell lines, with a GI₅₀ value of <0.01 μM . All of the synthesized compounds displayed cytotoxicity against A549 (non‐small‐cell lung cancer), HeLa (cervical carcinoma), MCF‐7 (breast cancer), and HCT116 (colon carcinoma) with 50 % inhibitory concentration (IC₅₀) values ranging from 0.011 to 8.56 μM . A cell cycle assay revealed that these compounds arrested the G2/M phase of the cell cycle. Two compounds exhibited strong inhibitory effects on tubulin assembly with IC₅₀ values of 0.71 and 0.79 μM . Moreover, dot‐blot analysis of cyclin B1 demonstrated that some of the congeners strongly induced cyclin B1 protein levels. Molecular docking studies indicated that these compounds occupy the colchicine binding site of tubulin.     

Engineered s-Triazine-Based Dendrimer-Honokiol Conjugates as Targeted MMP-2/9 Inhibitors for Halting Hepatocellular Carcinoma

Despite the advances in developing MMP-2/9 inhibitors, off-target side effects and pharmacokinetics problems remain major challenges hindering their clinical success in cancer therapy. However, recent targeting strategies have clearly revitalized MMP research. Herein, we introduce new s-triazine-based dendrimers endowed with intrinsic MMP-2/9 inhibitory potential and tetherable to hepatocellular carcinoma-specific targeting ligands and anticancer agents via biodegradable linkages for targeted therapy. The designed dendrimeric platform was built with potential zinc-binding branching linkers (hydrazides) and termini (carboxylic acids and hydrazides) to confer potency against MMP-2/9. Preliminary cytotoxicity screening and MMP-2/9 inhibition assay of the free dendrimers revealed promising potency (MMP-9; IC₅₀=0.35–0.57 μM, MMP-2; IC₅₀=0.39–0.77 μM) within their safe doses (EC₁₀₀=94.15–42.75 μM). The hydrazide dendrimer was comparable to NNGH and superior to the carboxylic acid analogue. MTT assay showed that the free dendrimers were superior to the reference anticancer agent honokiol. Their anticancer potency was enhanced by HK conjugation, targeting ligands installation and PEGylation as exemplified by the hydrazide dendrimer conjugate (TPG₃−NH₂)-SuHK-FA-SuPEG (Huh-7; IC₅₀=5.54 μM, HepG-2; IC₅₀=10.07 μM) being 4 folds more active than HK, followed by the carboxylic acid conjugate (TPG₃−OH)-HK-LA-PEG (Huh-7; IC₅₀=14.97, HepG-2; IC₅₀=21.29 μM). This was consistent with apoptosis studies.     

Design,Synthesis, and Evaluation of Novel Ferroquine and Phenylequine Analogues as Potential Antiplasmodial Agents

7‐Chloroquinoline‐based antimalarial drugs are effective in the inhibition of hemozoin formation in the food vacuole of the Plasmodium parasite, the causative agent of malaria. We synthesized five series of ferroquine (FQ) and phenylequine (PQ) derivatives, which display good in vitro efficacy toward both the chloroquine‐sensitive (CQS) NF54 (IC₅₀: 4.2 nm ) and chloroquine‐resistant (CQR) Dd2 (IC₅₀: 33.7 nm ) strains of P. falciparum. Several compounds were found to have good inhibitory activity against β‐hematin formation in an NP‐40 detergent assay, with IC₅₀ values ranging between 10.4 and 19.2 μm .     

Design and Synthesis of Imidazo[2,1‐b]thiazole–Chalcone Conjugates: Microtubule‐Destabilizing Agents

A series of chalcone conjugates featuring the imidazo[2,1‐b]thiazole scaffold was designed, synthesized, and evaluated for their cytotoxic activity against five human cancer cell lines (MCF‐7, A549, HeLa, DU‐145 and HT‐29). These new hybrid molecules have shown promising cytotoxic activity with IC₅₀ values ranging from 0.64 to 30.9 μM . Among them, (E)‐3‐(6‐(4‐fluorophenyl)‐2,3‐bis(4‐methoxyphenyl)imidazo[2,1‐b]thiazol‐5‐yl)‐1‐(pyridin‐2‐yl)prop‐2‐en‐1‐one ( 11 x ) showed potent antiproliferative activity with IC₅₀ values ranging from 0.64 to 1.44 μM in all tested cell lines. To investigate the mechanism of action, the detailed biological aspects of this promising conjugate ( 11 x ) were carried out on the A549 lung cancer cell line. The tubulin polymerization assay and immunofluoresence analysis results suggest that this conjugate effectively inhibits microtubule assembly in A549 cells. Flow cytometric analysis revealed that this conjugate induces cell‐cycle arrest in the G2/M phase and leads to apoptotic cell death. This was further confirmed by Hoechst staining, activation of caspase‐3, DNA fragmentation analysis, and Annexin V–FITC assay. Moreover, molecular docking studies indicated that this conjugate ( 11 x) interacts and binds efficiently with the tubulin protein.     

N‐Cinnamoylation of Antimalarial Classics: Quinacrine Analogues with Decreased Toxicity and Dual‐Stage Activity

Plasmodium falciparum, the causative agent of the most lethal form of malaria, is becoming increasingly resistant to most available drugs. A convenient approach to combat parasite resistance is the development of analogues of classical antimalarial agents, appropriately modified in order to restore their relevance in antimalarial chemotherapy. Following this line of thought, the design, synthesis and in vitro evaluation of N‐cinnamoylated quinacrine surrogates, 9‐(N‐cinnamoylaminobutyl)‐amino‐6‐chloro‐2‐methoxyacridines, is reported. The compounds were found to be highly potent against both blood‐stage P. falciparum, chloroquine‐sensitive 3D7 (IC₅₀=17.0–39.0 nM ) and chloroquine‐resistant W2 and Dd2 strains (IC₅₀=3.2–41.2 and 27.1–131.0 nM , respectively), and liver‐stage P. berghei (IC₅₀=1.6–4.9 μM ) parasites. These findings bring new hope for the possible future “rise of a fallen angel” in antimalarial chemotherapy, with a potential resurgence of quinacrine‐related compounds as dual‐stage antimalarial leads.     

Synthesis of Combretastatin-A4 Carboxamidest that Mimic Sulfonyl Piperazines by a Molecular Hybridization Approach: in vitro Cytotoxicity Evaluation and Inhibition of Tubulin Polymerization

Molecular hybridization approach is a promising structural modification tool to design new chemical entities (NCEs) by mimicking two different pharmacophoric units into one scaffold to enhance the biological properties. With this aim, combretastatin-A4 acids were integrated with sulfonyl piperazine scaffolds as a one molecular platform and evaluated for their in vitro antiproliferative activity against a panel of human cancer lines cell lines namely, lung (A549), mouse melanoma (B16F10), breast (MDA MB-231and MCF-7) and colon (HCT-15) by MTT assay. Amongst which the compound (E)-3-(4-Chlorophenyl)-1-(4-((4-chlorophenyl)sulfonyl)piperazin-1-yl)-2-(3,4,5-trimethoxyphenyl)prop-2-en-1-one ( 5 ab ) displayed significant IC₅₀ values in the range of 0.36 to 7.08 μm against the selected cancer cell lines. Moreover, 5 ab was found to be the most potent member of this series with IC₅₀ 0.36±0.02 μm . Further investigations revealed that the compound 5 ab displayed significant inhibition of tubulin assembly with IC₅₀ 5.24±0.06 μm and molecular docking studies also disclosed the binding of 5 ab effectively in CA4 binding space at the colchicine binding site. The flow cytometric analysis demonstrated that the compound 5 ab caused cell cycle arrest at G2/M phase in A549 cells. Compound 5 ab induced apoptosis in A549 cells which was further evaluated by different staining assays such as DAPI and AO which undoubtedly speculated, the induction of apoptosis. To study the anti-migration with 5 ab , cell migration/scratch wound assay was performed and the extent of apoptosis was studied by Annexin-V, including mitochondrial potential by JC-1 staining.     

Antiplasmodial and Antimalarial Activity of 3,5-Diarylidenetetrahydro-2H-pyran-4(3H)-ones via Inhibition of Plasmodium falciparum Pyridoxal Synthase

A series of 22 different 3,5-diarylidenetetrahydro-2H-pyran-4(3H)-ones (DATPs) were synthesized, characterized, and screened for their in vitro antiplasmodial activities against chloroquine (CQ)-sensitive Pf3D7, CQ-resistant PfINDO, and artemisinin-resistant PfMRA-1240 strains of Plasmodium falciparum. DATP 19 ( 3,5-bis(4-hydroxy-3,5-dimethoxybenzylidene)tetrahydro-2H-pyran-4(3H)-one) was found to be the most potent (IC₅₀ 1.07 μM) against PfMRA-1240, whereas 21 (3,5-bis(3,4,5-trimethoxybenzylidene)tetrahydro-2H-pyran-4(3H)-one) showed IC₅₀ values of 1.72 and 1.44 μM against Pf3D7 and PfINDO, respectively. Resistance indices (RI) as low as 0.2 to 0.5 for 10 (3,5-bis(4-nitrobenzylidene)tetrahydro-2H-pyran-4(3H)-one) and 20 (3,5-bis(3-nitrobenzylidene)tetrahydro-2H-pyran-4(3H)-one), and <1 for most other DATPs reveals their greater potency against resistant strains than the sensitive one. The single-crystal XRD data for DATP 21 are reported. In silico support was obtained through docking studies. Killing all three strains within 4–8 h, these DATPs showed rapid kill kinetics toward the trophozoite stage. Furthermore, DATP 18 (3,5-bis(quinolin-4-ylmethylene)tetrahydro-2H-pyran-4(3H)-one) inhibited PfPdx1 enzyme activity with IC₅₀ 20.34 μM, which is about twofold lower than that (IC₅₀ 43 μM) for an already known inhibitor 4PEHz. At an oral dose of 300 mg/kg body weight, DATPs 19 and 21 were found to be nontoxic to mice, and at 100 mg/kg body weight, DATP 19 was found to suppress parasitaemia, which led to an increase in median survival time by three days relative to untreated control mice in a malaria curative study.     

2‐Anilino‐3‐Aroylquinolines as Potent Tubulin Polymerization Inhibitors

Several 2‐anilino‐3‐aroylquinolines were designed, synthesized, and screened for their cytotoxic activity against five human cancer cell lines: HeLa, DU‐145, A549, MDA‐MB‐231, and MCF‐7. Their IC₅₀ values ranged from 0.77 to 23.6 μm . Among the series, compounds 7 f [(4‐fluorophenyl)(2‐((4‐fluorophenyl)amino)quinolin‐3‐yl)methanone] and 7 g [(4‐chlorophenyl)(2‐((4‐fluorophenyl)amino)quinolin‐3‐yl)methanone] showed remarkable antiproliferative activity against human lung cancer and prostate cancer cell lines. The IC₅₀ values for inhibiting tubulin polymerization were 2.24 and 2.10 μm for compounds 7 f and 7 g , respectively, and were much lower than that of the reference compound E7010 [N‐(2‐(4‐hydroxyphenylamino)pyridin‐3‐yl)‐4‐methoxybenzenesulfonamide]. Furthermore, flow cytometric analysis revealed that these compounds arrest the cell cycle at the G₂/M phase, leading to apoptosis. Apoptosis was also confirmed by mitochondrial membrane potential, Annexin V–FITC assay, and intracellular ROS generation. Immunohistochemistry, western blot, and tubulin polymerization assays showed that these compounds disrupt tubulin polymerization. Molecular docking studies revealed that these compounds bind efficiently to β‐tubulin at the colchicine binding site.     

Synthesis and Antitrypanosomal Activity of 1,4-Disubstituted Triazole Compounds Based on a 2-Nitroimidazole Scaffold: a Structure-Activity Relationship Study

Chagas disease affects 6–8 million people worldwide, remaining a public health concern. Toxicity, several adverse effects and inefficiency in the chronic stage of the disease are the major challenges regarding the available treatment protocols. This work involved the synthesis of twenty-two 1,4-disubstituted-1,2,3-triazole analogues of benznidazole (BZN), by using a click chemistry strategy. Analogues were obtained in moderate to good yields (40-97 %). Antitrypanosomal activity was evaluated against the amastigote forms of Trypanosoma cruzi. Compound 8 a (4-(2-nitro-1H-imidazol-1-yl)methyl)-1-phenyl-1H-1,2,3-triazole) without substituents on phenyl ring showed similar biological activity to BZN (IC₅₀=3.0 μM, SI>65.3), with an IC₅₀=3.1 μM and SI>64.5. Compound 8 o (3,4-di-OCH₃−Ph) with IC₅₀ = 0.65 μM was five-fold more active than BZN, and showed an excellent selectivity index (SI>307.7). Compound 8 v (3-NO₂, 4-CH₃−Ph) with IC₅₀=1.2 μM and relevant SI>166.7, also exhibited higher activity than BZN. SAR analysis exhibited a pattern regarding antitrypanosomal activity relative to BZN, in compounds with electron-withdrawing groups (Hammett σ+) at position 3, and electron-donating groups (Hammett σ-) at position 4, as observed in 8 o and 8 v . Further research might explore in vivo antitrypanosomal activity of promising analogues 8 a , 8 o , and 8 v . Overall, this study indicates that approaches such as the bioisosteric replacement of amide group by 1,2,3-triazole ring, the use of click chemistry as a synthesis strategy, and design tools like Craig-plot and Topliss tree are promising alternatives to drug discovery.     

Structure–Activity and Structure–Toxicity Relationships of Peptoid-Based Histone Deacetylase Inhibitors with Dual-Stage Antiplasmodial Activity

Novel malaria intervention strategies are of great importance, given the development of drug resistance in malaria-endemic countries. In this regard, histone deacetylases (HDACs) have emerged as new and promising malaria drug targets. In this work, we present the design, synthesis, and biological evaluation of 20 novel HDAC inhibitors with antiplasmodial activity. Based on a previously discovered peptoid-based hit compound, we modified all regions of the peptoid scaffold by using a one-pot multicomponent pathway and submonomer routes to gain a deeper understanding of the structure–activity and structure–toxicity relationships. Most compounds displayed potent activity against asexual blood-stage P. falciparum parasites, with IC₅₀ values in the range of 0.0052–0.25 μm and promising selectivity over mammalian cells (SI^Pf3D7/HepG2: 170–1483). In addition, several compounds showed encouraging sub-micromolar activity against P. berghei exo-erythrocytic forms (PbEEF). Our study led to the discovery of the hit compound N-(2-(benzylamino)-2-oxoethyl)-N-(4-(hydroxycarbamoyl)benzyl)-4-isopropylbenzamide ( 2 h ) as a potent and parasite-specific dual-stage antiplasmodial HDAC inhibitor (IC₅₀ Pf3D7=0.0052 μm , IC₅₀ PbEEF=0.016 μm ).     

Synthesis,Cytotoxicity, and Insight into the Mode of Action of Re(CO)3 Thymidine Complexes

Nucleoside analogues are extensively used in the treatment of cancer and viral diseases. The antiproliferative properties of organorhenium(I) complexes, however, have been scarcely explored to date. Herein we present the syntheses, characterization, and in vitro evaluation of Re^I(CO)₃ core complexes of thymidine and uridine. For the binding of the Re^I(CO)₃ core, a tridentate dipicolylamine metal chelate was introduced at positions C5′, C2′, N3, and C5 with spacers of various lengths. The corresponding organometallic thymidine complexes were fully characterized by IR and NMR spectroscopy and mass spectrometry. Their cytotoxicity was assessed against the A549 lung carcinoma cell line. Toxicity is dependent on the site and mode of conjugation as well as on the nature and the length of the tether. Moderate toxicity was observed for conjugates carrying the rhenium moiety at position C5′ or N3 (IC₅₀=124–160 μM ). No toxicity was observed for complexes modified at C2′ or C5. Complex 53 , with a dodecylene spacer at C5′, exhibits remarkable toxicity and is more potent than cisplatin, with an IC₅₀ value of 6.0 μM . To the best of our knowledge, this is the first report of the antiproliferative properties of [M(CO)₃]⁺¹–nucleoside conjugates. In competitive inhibition experiments with A549 cell lysates and purified recombinant human thymidine kinase 1 (hTK‐1), enzyme inhibition was observed for complexes modified at either N3 or C5′, but our results suggest that the toxicity cannot be attributed solely to interaction with hTK‐1.     

Comparison of the Effects of Statins on A549 Nonsmall-Cell Lung Cancer Cell Line Lipids Using Fourier Transform Infrared Spectroscopy: Rosuvastatin Stands Out

Statins are commonly prescribed antilipidemic and anticholesterol class of drugs. In addition to their major role, they have been found to have anticancer effects on in vitro, animal and clinical studies. The aim of this study was to investigate the effects of six different statins (rosuvastatin, pravastatin, simvastatin, lovastatin, fluvastatin, and atorvastatin) on A549 cancer cells lipids by Fourier transform infrared (FTIR) spectroscopy. Proliferation tests were carried out to detect the half-maximal inhibitory concentrations (IC₅₀) of each statin on A549 cells. The IC₅₀ values were 50 μM for simvastatin, 150 μM for atorvastatin and pravastatin, and 170 μM for fluvastatin, 200 μM for rosuvastatin and lovastatin on A549 cells. No correlation was found between the antiproliferative effects of the statins and lipid-lowering effect. The cells were treated with IC₅, IC₁₀, and IC₅₀ values of each statins concentration and lipid extracts were compared using FTIR spectroscopy. The results indicated that different statins had different effects on the lipid content of A549 cells. The FTIR spectra of the lipid exctracts of statin-treated A549 cells indicated that the value of hydrocarbon chain length, unsaturation index, oxidative stress level, and phospholipid containing lipids increased except for rosuvastatin-treated A549 cells. In addition, rosuvastatin significantly lowered cholesterol ester levels. In conclusion, the contrasting effects of rosuvastatin should be further investigated.     

2-amino-3,4,5-trimethoxybenzophenones as potent tubulin polymerization inhibitors

A series of novel 2‐amino‐3,4,5‐trimethoxybenzophenone analogues exhibited excellent activity as tubulin polymerization inhibitors by targeting the colchicine binding site of microtubules. The lead compound 17 exhibited an IC₅₀ value of 1.6 μM , similar to that of combretastatin A‐4 (IC₅₀=1.9 μM ). It also displayed remarkable anti‐proliferative activity, with IC₅₀ values ranging from 7–16 nM against a variety of human cancer cell lines and one MDR(+) cancer cell line. SAR information indicated that the introduction of an amino group at the C2 position of benzophenone ring A and the C3’ position of benzophenone ring B play important roles in maximizing activity.     

Tropinone-Derived Alkaloids as Potent Anticancer Agents: Synthesis,Tyrosinase Inhibition,Mechanism of Action,DFT Calculation,and Molecular Docking Studies

A new series of hybrid compounds with tropinone and thiazole rings in the structure was designed and synthesized as potential anticancer agents. They were tested against human multiple myeloma (RPMI 8226), lung carcinoma (A549), breast adenocarcinoma (MDA-MB-231), and mouse skin melanoma (B16-F10) cell lines. Toxicity was tested on human normal skin fibroblasts (HSF) and normal colon fibroblasts (CCD-18Co). The growth inhibition mechanism of the most active derivative was analyzed through investigation of its effect on the distribution of cell cycle phases and ability to induce apoptosis and necrosis in RPMI 8226 and A549 cancer cells. The tyrosinase inhibitory potential was assessed, followed by molecular docking studies. Compounds 3a–3h show high anticancer activity against MDA-MB-231 and B16-F10 cell lines with IC₅₀ values of 1.51–3.03 µM. Moreover, the cytotoxic activity of the investigated compounds against HSF and CCD-18Co cells was 8–70 times lower than against the cancer cells or no toxicity was shown in our tests, with derivative 3a being particularly successful. The mechanism of action of compound 3a in RPMI 8226 cell was shown to be through induction of cell death through apoptosis. The derivatives show ability to inhibit the tyrosinase activity with a mixed mechanism of inhibition. The final molecular docking results showed for IC₅₀ distinct correlation with experiment.     

Synthesis of Tamoxifen-Artemisinin and Estrogen-Artemisinin Hybrids Highly Potent Against Breast and Prostate Cancer

In the search for new and effective treatments of breast and prostate cancer, a series of hybrid compounds based on tamoxifen, estrogens, and artemisinin were successfully synthesized and analyzed for their in vitro activities against human prostate (PC-3) and breast cancer (MCF-7) cell lines. Most of the hybrid compounds exhibit a strong anticancer activity against both cancer cell lines – for example, EC₅₀ (PC-3) down to 1.07 μM, and EC₅₀ (MCF-7) down to 2.08 μM – thus showing higher activities than their parent compounds 4-hydroxytamoxifen (afimoxifene, 7 ; EC₅₀=75.1 (PC-3) and 19.3 μM (MCF-7)), dihydroartemisinin ( 2 ; EC₅₀=263.6 (PC-3) and 49.3 μM (MCF-7)), and artesunic acid ( 3 ; EC₅₀=195.1 (PC-3) and 32.0 μM (MCF-7)). The most potent compounds were the estrogen-artemisinin hybrids 27 and 28 (EC₅₀=1.18 and 1.07 μM, respectively) against prostate cancer, and hybrid 23 (EC₅₀=2.08 μM) against breast cancer. These findings demonstrate the high potential of hybridization of artemisinin and estrogens to further improve their anticancer activities and to produce synergistic effects between linked pharmacophores.     

Novel Phenylmethylenecyclohexenone Derivatives as Potent TrxR Inhibitors Display High Antiproliferative Activity and Induce ROS,Apoptosis, and DNA Damage

The natural product piperlonguminine (PL) has been shown to exert potential anticancer activity against several types of cancer via elevation of reactive oxidative species (ROS). However, the application of PL has been limited due to its poor water solubility and moderate activity. To improve PL's potency, we designed and synthesized a series of 17 novel phenylmethylenecyclohexenone derivatives and evaluated their pharmacological properties. Most of them exerted antiproliferative activities against four cancer cell lines with IC₅₀ values lower than PL. Among these, compound 10 e not only showed good water solubility and exerted the most potent antiproliferative activity against HGC27 cells (IC₅₀=0.76 μM), which was 10-fold lower than PL (IC₅₀=7.53 μM), but also exhibited lower cytotoxicity in human normal gastric epithelial cells GES-1 compared with HGC27 cells. Mechanistically, compound 10 e inhibited thioredoxin reductase (TrxR) activity, increased ROS levels, and diminished mitochondrial transmembrane potential (MTP) in HGC27 cells. Furthermore, 10 e also induced G₂/M cell-cycle arrest, and triggered cancer cell apoptosis through the regulation of apoptotic proteins. Finally, 10 e promoted DNA damage in HGC27 cells via the activation of the H2AX(S139ph) and p53 signaling. In conclusion, 10 e , with prominent tumor selectivity and water solubility, could be a promising candidate for the treatment of cancer and, as such, warrants further investigation.     

Synthesis and Biological Evaluation of Benzo[b]furans as Inhibitors of Tubulin Polymerization and Inducers of Apoptosis

A series of benzo[b]furans was synthesized with modification at the 5‐position of the benzene ring by introducing C‐linked substituents (aryl, alkenyl, alkynyl, etc.). These compounds were evaluated for their antiproliferative activities, inhibition of tubulin polymerization, and cell‐cycle effects. Some compounds in this series displayed excellent activity in the nanomolar range against lung cancer (A549) and renal cell carcinoma (ACHN) cancer cell lines. (6‐Methoxy‐5‐((4‐methoxyphenyl)ethynyl)‐3‐methylbenzofuran‐2‐yl)(3,4,5‐trimethoxyphenyl)methanone ( 26 ) and (E)‐3‐(6‐methoxy‐3‐methyl‐2‐(1‐(3,4,5‐trimethoxyphenyl)vinyl)benzofuran‐5‐yl)prop‐2‐en‐1‐ol ( 36 ) showed significant activity in the A549 cell line, with IC₅₀ values of 0.08 and 0.06 μM , respectively. G₂/M cell‐cycle arrest and subsequent apoptosis was observed in the A549 cell line after treatment with these compounds. The most active compound in this series, 36 , also inhibited tubulin polymerization with a value similar to that of combretastatin A‐4 (1.95 and 1.86 μM , respectively). Furthermore, detailed biological studies such as Hoechst 33258 staining, DNA fragmentation and caspase‐3 assays, and western blot analyses with the pro‐apoptotic protein Bax and the anti‐apoptotic protein Bcl‐2 also suggested that these compounds induce cell death by apoptosis. Molecular docking studies indicated that compound 36 interacts and binds efficiently with the tubulin protein.