Design,Synthesis, and Evaluation of an 18F‐Labeled Radiotracer Based on Celecoxib–NBD for Positron Emission Tomography (PET) Imaging of Cyclooxygenase‐2 (COX‐2)

A series of novel fluorine‐containing cyclooxygenase‐2 (COX‐2) inhibitors was designed and synthesized based on the previously reported fluorescent COX‐2 imaging agent celecoxib–NBD ( 3 ; NBD=7‐nitrobenzofurazan). In vitro COX‐1/COX‐2 inhibitory data show that N‐(4‐fluorobenzyl)‐4‐(5‐p‐tolyl‐3‐trifluoromethylpyrazol‐1‐yl)benzenesulfonamide ( 5 ; IC₅₀=0.36 μM , SI>277) and N‐fluoromethyl‐4‐(5‐p‐tolyl‐3‐trifluoromethylpyrazol‐1‐yl)benzenesulfonamide ( 6 ; IC₅₀=0.24 μM , SI>416) are potent and selective COX‐2 inhibitors. Compound 5 was selected for radiolabeling with the short‐lived positron emitter fluorine‐18 (¹⁸F) and evaluated as a positron emission tomography (PET) imaging agent. Radiotracer [¹⁸F] 5 was analyzed in vitro and in vivo using human colorectal cancer model HCA‐7. Although radiotracer uptake into COX‐2‐expressing HCA‐7 cells was high, no evidence for COX‐2‐specific binding was found. Radiotracer uptake into HCA‐7 tumors in vivo was low and similar to that of muscle, used as reference tissue.     

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 Biological Evaluation of Imidazo[2,1‐b][1,3,4]thiadiazole‐Linked Oxindoles as Potent Tubulin Polymerization Inhibitors

A series of imidazo[2,1‐b][1,3,4]thiadiazole‐linked oxindoles composed of an A, B, C and D ring system were synthesized and investigated for anti‐proliferative activity in various human cancer cell lines; test compounds were variously substituted at rings C and D. Among them, compounds 7 ((E)‐5‐fluoro‐3‐((6‐p‐tolyl‐2‐(3,4,5‐trimethoxyphenyl)‐imidazo[2,1‐b][1,3,4]thiadiazol‐5‐yl)methylene)indolin‐2‐one), 11 ((E)‐3‐((6‐p‐tolyl‐2‐(3,4,5‐trimethoxyphenyl)imidazo[2,1‐b][1,3,4]thiadiazol‐5‐yl)methylene)indolin‐2‐one), and 15 ((E)‐6‐chloro‐3‐((6‐phenyl‐2‐(3,4,5‐trimethoxyphenyl)imidazo[2,1‐b][1,3,4]thiadiazol‐5‐yl)methylene)indolin‐2‐one) exhibited potent anti‐proliferative activity. Treatment with these three compounds resulted in accumulation of cells in G₂/M phase, inhibition of tubulin assembly, and increased cyclin‐B1 protein levels. Compound 7 displayed potent cytotoxicity, with an IC₅₀ range of 1.1–1.6 μM , and inhibited tubulin polymerization with an IC₅₀ value (0.15 μM ) lower than that of combretastatin A‐4 (1.16 μM ). Docking studies reveal that compounds 7 and 11 bind with αAsn101, βThr179, and βCys241 in the colchicine binding site of tubulin.     

NBD‐Based Green Fluorescent Ligands for Typing of Thymine‐Related SNPs by Using an Abasic Site‐Containing Probe DNA

The binding behavior of green fluorescent ligands, derivatives of 7‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBD), with DNA duplexes containing an abasic (AP) site is studied by thermal denaturation and fluorescence experiments. Among NBD derivatives, N¹‐(7‐nitrobenzo[c][1,2,5]oxadiazol‐4‐yl)propane‐1,3‐diamine (NBD‐NH₂) is found to bind selectively to the thymine base opposite an AP site in a DNA duplex with a binding affinity of 1.52×10⁶ M ^?1. From molecular modeling studies, it is suggested that the NBD moiety binds to thymine at the AP site and a protonated amino group tethered to the NBD moiety interacts with the guanine base flanking the AP site. Green fluorescent NBD‐NH₂ is successfully applied for simultaneous G>T genotyping of PCR amplification products in a single cuvette in combination with a blue fluorescent ligand, 2‐amino‐6,7‐dimethyl‐4‐hydroxypteridine (diMe‐pteridine).     

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.     

Synthesis and Evaluation of 1‐(1‐(Benzo[b]thiophen‐2‐yl)cyclohexyl)piperidine (BTCP) Analogues as Inhibitors of Trypanothione Reductase

Thirty two analogues of phencyclidine were synthesised and tested as inhibitors of trypanothione reductase (TryR), a potential drug target in trypanosome and leishmania parasites. The lead compound BTCP ( 1 , 1‐(1‐benzo[b]thiophen‐2‐yl‐cyclohexyl) piperidine) was found to be a competitive inhibitor of the enzyme (K_i=1 μM ) and biologically active against bloodstream T. brucei (EC₅₀=10 μM ), but with poor selectivity against mammalian MRC5 cells (EC₅₀=29 μM ). Analogues with improved enzymatic and biological activity were obtained. The structure–activity relationships of this novel series are discussed.     

Toward the Development of Dual‐Targeted Glyceraldehyde‐3‐phosphate Dehydrogenase/Trypanothione Reductase Inhibitors against Trypanosoma brucei and Trypanosoma cruzi

A significant improvement in the treatment of trypanosomiases has been achieved with the recent development of nifurtimox–eflornithine combination therapy (NECT). As an alternative to drug combinations and as a means to overcome most of the antitrypanosomatid drug discovery challenges, a multitarget drug design strategy has been envisaged. To begin testing this hypothesis, we designed and developed a series of quinone–coumarin hybrids against glyceraldehyde‐3‐phosphate dehydrogenase/trypanothione reductase (GAPDH/TR). These enzymes belong to metabolic pathways that are vital to Trypanosoma brucei and Trypanosoma cruzi, and have thus been considered promising drug targets. The synthesized molecules were characterized for their dual‐target antitrypanosomal profile, both in enzyme assays and in in vitro parasite cultures. The merged derivative 2‐{[3‐(3‐dimethylaminopropoxy)‐2‐oxo‐2H‐chromen‐7‐yl]oxy}anthracene‐1,4‐dione ( 10 ) showed an IC₅₀ value of 5.4 μM against TbGAPDH and a concomitant K_i value of 2.32 μM against TcTR. Notably, 2‐{4‐[6‐(2‐dimethylaminoethoxy)‐2‐oxo‐2H‐chromen‐3‐yl]phenoxy}anthracene‐1,4‐dione (compound 6 ) displayed a remarkable EC₅₀ value for T. brucei parasites (0.026 μM ) combined with a very low cytotoxicity toward mammalian L6 cells (7.95 μM ). This promising low toxicity of compound 6 might be at least partially due to the fact that it does not interfere with human glutathione reductase.     

Synthesis and Biological Evaluation of 1‐Methyl‐1H‐indole–Pyrazoline Hybrids as Potential Tubulin Polymerization Inhibitors

A series of 1‐methyl‐1H‐indole–pyrazoline hybrids were designed, synthesized, and biologically evaluated as potential tubulin polymerization inhibitors. Among them, compound e19 [5‐(5‐bromo‐1‐methyl‐1H‐indol‐3‐yl)‐3‐(3,4,5‐trimethoxyphenyl)‐4,5‐dihydro‐1H‐pyrazole‐1‐carboxamide] showed the most potent inhibitory effect on tubulin assembly (IC₅₀=2.12 μm ) and in vitro growth inhibitory activity against a panel of four human cancer cell lines (IC₅₀ values of 0.21–0.31 μm ). Further studies confirmed that compound e19 can induce HeLa cell apoptosis, cause cell‐cycle arrest in G₂/M phase, and disrupt the cellular microtubule network. These studies, along with molecular docking and 3D‐QSAR modeling, provide an important basis for further optimization of compound e19 as a potential anticancer agent.     

A New Class of 1‐Aryl‐5,6‐dihydropyrrolo[2,1‐a]isoquinoline Derivatives as Reversers of P‐Glycoprotein‐Mediated Multidrug Resistance in Tumor Cells

A number of aza‐heterocyclic compounds, which share the 5,6‐dihydropyrrolo[2,1‐a]isoquinoline (DHPIQ) scaffold with members of the lamellarin alkaloid family, were synthesized and evaluated for their ability to reverse in vitro multidrug resistance in cancer cells through inhibition of P‐glycoprotein (P‐gp) and/or multidrug‐resistance‐associated protein 1. Most of the investigated DHPIQ compounds proved to be selective P‐gp modulators, and the most potent modulator, 8,9‐diethoxy‐1‐(3,4‐diethoxyphenyl)‐3‐(furan‐2‐yl)‐5,6‐dihydropyrrolo[2,1‐a]isoquinoline‐2‐carbaldehyde, attained sub‐micromolar inhibitory potency (IC₅₀: 0.19 μm ). Schiff bases prepared by the condensation of some 1‐aryl‐DHPIQ aldehydes with p‐aminophenol also proved to be of some interest, and one of them, 4‐((1‐(4‐fluorophenyl)‐5,6‐dihydro‐8,9‐dimethoxypyrrolo[2,1‐a]isoquinolin‐2‐yl)methyleneamino)phenol, had an IC₅₀ value of 1.01 μm . In drug combination assays in multidrug‐resistant cells, some DHPIQ compounds, at nontoxic concentrations, significantly increased the cytotoxicity of doxorubicin in a concentration‐dependent manner. Studies of structure–activity relationships and investigation of the chemical stability of Schiff bases provided physicochemical information useful for molecular optimization of lamellarin‐like cytotoxic drugs active toward chemoresistant tumors as well as nontoxic reversers of P‐gp‐mediated multidrug resistance in tumor cells.     

Structure–Activity Relationship of Tumor‐Selective 5‐Substituted 2‐Amino‐3‐carboxymethylthiophene Derivatives

Methyl‐2‐amino‐5‐[2‐(4‐methoxyphenethyl)]thiophene‐3‐carboxylate ( 8 c ) is the prototype of a well‐defined class of tumor‐selective agents. Compound 8 c preferentially inhibited the proliferation of a number of tumor cell lines including many human T‐lymphoma/leukemia cells, but also several prostate, renal, central nervous system and liver tumor cell types. Instead, a broad variety of other tumor cell lines including B‐lymphomas and HeLa cells were not affected. The tumor selectivity (TS; selectivity index or preferential suppression of CEM lymphoma (IC₅₀=0.90 μM ) versus HeLa tumor cell carcinoma (IC₅₀=39 μM )) amounted up to ～43 for 8 c . At higher concentrations, the compound proved cytotoxic rather than cytostatic. The antiproliferative potency and selectivity of 8 c could be preserved by replacing the ethyl linker between the 2‐amino‐3‐carboxymethylthiophene and the substituted aryl by a thioalkyl but not by an oxyalkyl nor an aminoalkyl. Among >50 novel 8 c derivatives, the 5‐(4‐ethyl‐ and 4‐isopropylarylmethylthio)thiophene analogues, methyl‐2‐amino‐5‐((4‐ethylphenylthio)methyl)thiophene‐3‐carboxylate ( 13 m ) and methyl‐2‐amino‐5‐((4‐isopropylphenylthio)methyl)thiophene‐3‐carboxylate ( 13 n ), were more potent (IC₅₀: 0.3–0.4 μM ) and selective (TS: 100–144) anti‐T‐lymphoma/leukemia agents than the prototype compound.     

Designing Dual Transglutaminase 2/Histone Deacetylase Inhibitors Effective at Halting Neuronal Death

In recent years there has been a clear consensus that neurodegenerative conditions can be better treated through concurrent modulation of different targets. Herein we report that combined inhibition of transglutaminase 2 (TG2) and histone deacetylases (HDACs) synergistically protects against toxic stimuli mediated by glutamate. Based on these findings, we designed and synthesized a series of novel dual TG2–HDAC binding agents. Compound 3 [(E)‐N‐hydroxy‐5‐(3‐(4‐(3‐oxo‐3‐(pyridin‐3‐yl)prop‐1‐en‐1‐yl)phenyl)thioureido)pentanamide] emerged as the most interesting of the series, being able to inhibit TG2 and HDACs both in vitro (TG2 IC₅₀=13.3±1.5 μm , HDAC1 IC₅₀=3.38±0.14 μm , HDAC6 IC₅₀=4.10±0.13 μm ) and in cell‐based assays. Furthermore, compound 3 does not exert any toxic effects in cortical neurons up to 50 μm and protects neurons against toxic insults induced by glutamate (5 mm ) with an EC₅₀ value of 3.7±0.5 μm .     

Novel Tacrine‐Grafted Ugi Adducts as Multipotent Anti‐Alzheimer Drugs: A Synthetic Renewal in Tacrine–Ferulic Acid Hybrids

Herein we describe the design, multicomponent synthesis, and biological, molecular modeling and ADMET studies, as well as in vitro PAMPA‐blood–brain barrier (BBB) analysis of new tacrine–ferulic acid hybrids (TFAHs). We identified (E)‐3‐(hydroxy‐3‐methoxyphenyl)‐N‐{8[(7‐methoxy‐1,2,3,4‐tetrahydroacridin‐9‐yl)amino]octyl}‐N‐[2‐(naphthalen‐2‐ylamino)2‐oxoethyl]acrylamide (TFAH 10 n ) as a particularly interesting multipotent compound that shows moderate and completely selective inhibition of human butyrylcholinesterase (IC₅₀=68.2 nM ), strong antioxidant activity (4.29 equiv trolox in an oxygen radical absorbance capacity (ORAC) assay), and good β‐amyloid (Aβ) anti‐aggregation properties (65.6 % at 1:1 ratio); moreover, it is able to permeate central nervous system (CNS) tissues, as determined by PAMPA‐BBB assay. Notably, even when tested at very high concentrations, TFAH 10 n easily surpasses the other TFAHs in hepatotoxicity profiling (59.4 % cell viability at 1000 μM ), affording good neuroprotection against toxic insults such as Aβ_1–40, Aβ_1–42, H₂O₂, and oligomycin A/rotenone on SH‐SY5Y cells, at 1 μM . The results reported herein support the development of new multipotent TFAH derivatives as potential drugs for the treatment of Alzheimer′s disease.     

Heme Oxygenase Inhibition by 1‐Aryl‐2‐(1H‐imidazol‐1‐yl/1H‐1,2,4‐triazol‐1‐yl)ethanones and Their Derivatives

Previous studies by our research group have been concerned with the design of selective inhibitors of heme oxygenases (HO‐1 and HO‐2). The majority of these were based on a four‐carbon linkage of an azole, usually an imidazole, and an aromatic moiety. In the present study, we designed and synthesized a series of inhibition candidates containing a shorter linkage between these groups, specifically, a series of 1‐aryl‐2‐(1H‐imidazol‐1‐yl/1H‐1,2,4‐triazol‐1‐yl)ethanones and their derivatives. As regards HO‐1 inhibition, the aromatic moieties yielding best results were found to be halogen‐substituted residues such as 3‐bromophenyl, 4‐bromophenyl, and 3,4‐dichlorophenyl, or hydrocarbon residues such as 2‐naphthyl, 4‐biphenyl, 4‐benzylphenyl, and 4‐(2‐phenethyl)phenyl. Among the imidazole‐ketones, five ( 36 – 39 , and 44 ) were found to be very potent (IC₅₀<5 μM ) toward both isozymes. Relative to the imidazole‐ketones, the series of corresponding triazole‐ketones showed four compounds ( 54 , 55 , 61 , and 62 ) having a selectivity index >50 in favor of HO‐1. In the case of the azole‐dioxolanes, two of them ( 80 and 85 ), each possessing a 2‐naphthyl moiety, were found to be particularly potent and selective HO‐1 inhibitors. Three non‐carbonyl analogues ( 87 , 89 , and 91 ) of 1‐(4‐chlorophenyl)‐2‐(1H‐imidazol‐1‐yl)ethanone were found to be good inhibitors of HO‐1. For the first time in our studies, two azole‐based inhibitors ( 37 and 39 ) were found to exhibit a modest selectivity index in favor of HO‐2. The present study has revealed additional candidates based on inhibition of heme oxygenases for potentially useful pharmacological and therapeutic applications.     

Cell‐Selective,Apoptosis‐inducing Rhodium(III) Crown Thiaether Complexes

Half‐sandwich rhodium(III) polypyridyl (pp) complexes with the metal atom capped by the facial crown thiaether 1,4,7‐trithiacyclononane [9]aneS₃ represent a promising class of apoptosis‐inducing potent cytostatic agents. The necrotic damage caused by the complexes is negligible. In vitro cytotoxicity assays with the human cancer cell lines MCF‐7 and HT‐29 and immortalized HEK‐293 cells indicate that the dicationic κ²N(imino) complexes [([9]aneS₃)RhCl(pp)]²⁺ are much more active than monocationic complexes [([9]aneS₃)RhCl₂(L)]⁺ (L=imidazole, CH₃CN). Whereas the κ²N(amino) complex [([9]aneS₃)RhCl(piperazine)]²⁺ is inactive, replacing piperazine with the structurally analogous κ²S (thiaether) ligand 1,4‐dithiane restores cytotoxicity as evidenced by IC₅₀ values in the range 8.1‐11.6 μM . Spectroscopic (CD, UV/Vis, NOESY) and viscosity measurements indicate that the active dppz complex 8 (IC₅₀ values: 4.7–8.9 μM ) exhibits strong intercalative binding towards DNA whereas the even more potent bipyrimidine complex 9 (IC₅₀ values: 0.6–1.9 μM ) causes no alteration of the duplex B conformation. Weaker intercalative binding is observed for the dpq complex 7 . A comparative annexin V–propidium iodide binding assay with lymphoma (BJAB) cells and healthy leukocytes demonstrates that the cytotoxic activity of complex 8 and particularly complex 9 is highly selective towards the malignant cells.     

Discovery of a Small‐Molecule pBcl‐2 Inhibitor that Overcomes pBcl‐2‐Mediated Resistance to Apoptosis

Although the role of Bcl‐2 phosphorylation is still under debate, it has been identified in a resistance mechanism to BH3 mimetics, for example ABT‐737 and S1 . We identified an S1 analogue, S1‐16 , as a small‐molecule inhibitor of pBcl‐2. S1‐16 efficiently kills EEE‐Bcl‐2 (a T69E, S70E, and S87E mutant mimicking phosphorylation)‐expressing HL‐60 cells and high endogenously expressing pBcl‐2 cells, by disrupting EEE‐Bcl‐2 or native pBcl‐2 interactions with Bax and Bak, followed by apoptosis. In vitro binding assays showed that S1‐16 binds to the BH3 binding groove of EEE‐Bcl‐2 (K_d=0.38 μM by ITC; IC₅₀=0.16 μM by ELISA), as well as nonphosphorylated Bcl‐2 (npBcl‐2; K_d=0.38 μM ; IC₅₀=0.12 μM ). However, ABT‐737 and S1 had much weaker affinities to EEE‐Bcl‐2 (IC₅₀=1.43 and >10 μM , respectively), compared with npBcl‐2 (IC₅₀=0.011 and 0.74 μM , respectively). The allosteric effect on BH3 binding groove by Bcl‐2 phosphorylation in the loop region was illustrated for the first time.     

Identification of a Small‐Molecule Inhibitor of HIV‐1 Assembly that Targets the Phosphatidylinositol (4,5)‐bisphosphate Binding Site of the HIV‐1 Matrix Protein

The development of drug resistance remains a critical problem for current HIV‐1 antiviral therapies, creating a need for new inhibitors of HIV‐1 replication. We previously reported on a novel anti‐HIV‐1 compound, N²‐(phenoxyacetyl)‐N‐[4‐(1‐piperidinylcarbonyl)benzyl]glycinamide ( 14 ), that binds to the highly conserved phosphatidylinositol (4,5)‐bisphosphate (PI(4,5)P₂) binding pocket of the HIV‐1 matrix (MA) protein. In this study, we re‐evaluate the hits from the virtual screen used to identify compound 14 and test them directly in an HIV‐1 replication assay using primary human peripheral blood mononuclear cells. This study resulted in the identification of three new compounds with antiviral activity; 2‐(4‐{[3‐(4‐fluorophenyl)‐1,2,4‐oxadiazol‐5‐yl]methyl})‐1‐piperazinyl)‐N‐(4‐methylphenyl)acetamide ( 7 ), 3‐(2‐ethoxyphenyl)‐5‐[[4‐(4‐nitrophenyl)piperazin‐1‐yl]methyl]‐1,2,4‐oxadiazole ( 17 ), and N‐[4‐ethoxy‐3‐(1‐piperidinylsulfonyl)phenyl]‐2‐(imidazo[2,1‐b][1,3]thiazol‐6‐yl)acetamide ( 18 ), with compound 7 being the most potent of these hits. Mechanistic studies on 7 demonstrated that it directly interacts with and functions through HIV‐1 MA. In accordance with our drug target, compound 7 competes with PI(4,5)P₂ for MA binding and, as a result, diminishes the production of new virus. Mutation of residues within the PI(4,5)P₂ binding site of MA decreased the antiviral effect of compound 7 . Additionally, compound 7 displays a broadly neutralizing anti‐HIV activity, with IC₅₀ values of 7.5–15.6 μM for the group M isolates tested. Taken together, these results point towards a novel chemical probe that can be used to more closely study the biological role of MA and could, through further optimization, lead to a new class of anti‐HIV‐1 therapeutics.     

Development of 3‐Phenyl‐N‐(2‐(3‐phenylureido)ethyl)‐thiophene‐2‐sulfonamide Compounds as Inhibitors of Antiapoptotic Bcl‐2 Family Proteins

Antiapoptotic Bcl‐2 family proteins, such as Bcl‐x_L, Bcl‐2, and Mcl‐1, are often overexpressed in tumor cells, which contributes to tumor cell resistance to chemotherapies and radiotherapies. Inhibitors of these proteins thus have potential applications in cancer treatment. We discovered, through structure‐based virtual screening, a lead compound with micromolar binding affinity to Mcl‐1 (inhibition constant (K_i)=3 μM ). It contains a phenyltetrazole and a hydrazinecarbothioamide moiety, and it represents a structural scaffold not observed among known Bcl‐2 inhibitors. This work presents the structural optimization of this lead compound. By following the scaffold‐hopping strategy, we have designed and synthesized a total of 82 compounds in three sets. All of the compounds were evaluated in a fluorescence‐polarization binding assay to measure their binding affinities to Bcl‐x_L, Bcl‐2, and Mcl‐1. Some of the compounds with a 3‐phenylthiophene‐2‐sulfonamide core moiety showed sub‐micromolar binding affinities to Mcl‐1 (K_i=0.3–0.4 μM ) or Bcl‐2 (K_i≈1 μM ). They also showed obvious cytotoxicity on tumor cells (IC₅₀<10 μM ). Two‐dimensional heteronuclear single quantum coherence NMR spectra of three selected compounds, that is, YCW‐E5, YCW‐E10, and YCW‐E11, indicated that they bind to the BH3‐binding groove on Bcl‐x_L in a similar mode to ABT‐737. Several apoptotic assays conducted on HL‐60 cells demonstrated that these compounds are able to induce cell apoptosis through the mitochondrial pathway. We propose that the compounds with the 3‐phenylthiophene‐2‐sulfonamide core moiety are worth further optimization as effective apoptosis inducers with an interesting selectivity towards Mcl‐1 and Bcl‐2.     

Design,Synthesis, Structure-Activity Relationship and Docking Studies of Novel Functionalized Arylvinyl-1,2,4-Trioxanes as Potent Antiplasmodial as well as Anticancer Agents

A novel series of synthetic functionalized arylvinyl-1,2,4-trioxanes ( 8 a – p ) has been prepared and assessed for their in vitro antiplasmodial activity against the chloroquine-resistant Pf INDO strain of Plasmodium falciparum by using a SYBR green-I fluorescence assay. Compounds 8 g (IC₅₀=0.051 μM; SI=589.41) and 8 m (IC₅₀=0.059 μM; SI=55.93) showed 11-fold and >9-fold more potent antiplasmodial activity, respectively, as compared to chloroquine (IC₅₀=0.546 μM; SI=36.63). Different in silico docking studies performed on many target proteins revealed that the most active arylvinyl-1,2,4-trioxanes ( 8 g and 8 m ) showed dihydrofolate reductase (DHFR) binding affinities on a par with those of chloroquine and artesunate. The in vitro cytotoxic potentials of 8 a – p were also evaluated against human lung (A549) and liver (HepG2) cancer cell lines along with immortalized normal lung (BEAS-2B) and liver (LO2) cell lines. Following screening, five derivatives viz. 8 a , 8 h , 8 l , 8 m and 8 o (IC₅₀=1.65–31.7 μM; SI=1.08–10.96) were found to show potent cytotoxic activity against (A549) lung cancer cell lines, with selectivity superior to that of the reference compounds artemisinin (IC₅₀=100 μM), chloroquine (IC₅₀=100 μM) and artesunic acid (IC₅₀=9.85 μM; SI=0.76). In fact, the most active 4-naphthyl-substituted analogue 8 l (IC₅₀=1.65 μM; SI >10) exhibited >60 times more cytotoxicity than the standard reference, artemisinin, against A549 lung cancer cell lines. In silico docking studies of the most active anticancer compounds, 8 l and 8 m , against EGFR were found to validate the wet lab results. In summary, a new series of functionalized aryl-vinyl-1,2,4-trioxanes ( 8 a – p ) has been shown to display dual potency as promising antiplasmodial and anticancer agents.     

N‐Benzyl Substitution of Polyhydroxypyrrolidines: The Way to Selective Inhibitors of Golgi α‐Mannosidase II

Inhibition of the biosynthesis of complex N‐glycans in the Golgi apparatus influences progress of tumor growth and metastasis. Golgi α‐mannosidase II (GMII) has become a therapeutic target for drugs with anticancer activities. One critical task for successful application of GMII drugs in medical treatments is to decrease their unwanted co‐inhibition of lysosomal α‐mannosidase (LMan), a weakness of all known potent GMII inhibitors. A series of novel N‐substituted polyhydroxypyrrolidines was synthesized and tested with modeled GH38 α‐mannosidases from Drosophila melanogaster (GMIIb and LManII). The most potent structures inhibited GMIIb (K_i=50–76 μm , as determined by enzyme assays) with a significant selectivity index of IC₅₀(LManII)/IC₅₀(GMIIb) >100. These compounds also showed inhibitory activities in in vitro assays with cancer cell lines (leukemia, IC₅₀=92–200 μm ) and low cytotoxic activities in normal fibroblast cell lines (IC₅₀>200 μm ). In addition, they did not show any significant inhibitory activity toward GH47 Aspergillus saitoiα1,2‐mannosidase. An appropriate stereo configuration of hydroxymethyl and benzyl functional groups on the pyrrolidine ring of the inhibitor may lead to an inhibitor with the required selectivity for the active site of a target α‐mannosidase.