Fluorescent In Situ Targeting Probes for Rapid Imaging of Ovarian‐Cancer‐Specific γ‐Glutamyltranspeptidase

γ‐Glutamyltranspeptidase (GGT) is a tumor biomarker that selectively catalyzes the cleavage of glutamate overexpressed on the plasma membrane of tumor cells. Here, we developed two novel fluorescent in situ targeting (FIST) probes that specifically target GGT in tumor cells, which comprise 1) a GGT‐specific substrate unit (GSH), and 2) a boron–dipyrromethene (BODIPY) moiety for fluorescent signalling. In the presence of GGT, sulfur‐substituted BODIPY was converted to amino‐substituted BODIPY, resulting in dramatic fluorescence variations. By exploiting this enzyme‐triggered photophysical property, we employed these FIST probes to monitor the GGT activity in living cells, which showed remarkable differentiation between ovarian cancer cells and normal cells. These probes represent two first‐generation chemodosimeters featuring enzyme‐mediated rapid, irreversible aromatic hydrocarbon transfer between the sulfur and nitrogen atoms accompanied by switching of photophysical properties.     

Enzyme‐Triggered Fluorescence Turn‐on: A Probe for Specifically Imaging Ovarian‐Cancer‐Related γ‐Glutamyltranspeptidase

A fluorescent turn‐on probe for specifically targeting γ ‐glutamyltranspeptidase (GGT ) was designed and synthesized by integrating boron‐dipyrromethene (BODIPY ) as a chromophore and glutathione (GSH ) as the GGT substrate. GGT ‐catalyzed the cleavage of the γ ‐glutamyl bond and generated the aromatic hydrocarbon transfer between the sulfur and the nitrogen atom in BODIPY , leading to distinct optical changes. Such specific responsiveness provides an easily distinguishable fluorescence signal to visualize the GGT activity in living cells and differentiate GGT ‐positive cancer cells from GGT ‐negative cells.     

An Activatable Photosensitizer Targeted to γ‐Glutamyltranspeptidase

We adopted a spirocyclization‐based strategy to design γ‐glutamyl hydroxymethyl selenorhodamine green (gGlu‐HMSeR) as a photo‐inactive compound that would be specifically cleaved by the tumor‐associated enzyme γ‐glutamyltranspeptidase (GGT) to generate the potent photosensitizer HMSeR. gGlu‐HMSeR has a spirocyclic structure and is colorless and does not show marked phototoxicity toward low‐GGT‐expressing cells or normal tissues upon irradiation with visible light. In contrast, HMSeR predominantly takes an open structure, is colored, and generates reactive oxygen species upon irradiation. The γ‐glutamyl group thus serves as a tumor‐targeting moiety for photodynamic therapy (PDT), switching on tumor‐cell‐specific phototoxicity. To validate this system, we employed chick chorioallantoic membrane (CAM), a widely used model for preliminary evaluation of drug toxicity. Photoirradiation after gGlu‐HMSeR treatment resulted in selective ablation of implanted tumor spheroids without damage to healthy tissue.     

The Chaperone‐like Activity and Structure of Mutant H119G of Rat Lens αB‐crystallin: A Study of Divalent Metal Ion Binding Site

The molecular chaperone αB‐crystallin, the major player in maintaining the transparency of the eye lens, preventing the aggregation of stress‐damaged and aging lens proteins from aggregation. In nonlenticular cells, it is involved in various neurological diseases, diabetes, and cancer. The role of some metal ions in the αB‐crystallin biology has been reported. Theoretical calculations have proposed that the coordination sites involving His101, His119, Lys121, His18 and Glu99 of human αB‐crystallin were the binding sites for divalent metal ions. Our previous mutagenesis study suggested that His18 rat lens αB‐crystallin is a crucial binding site for Cu(II) and Zn(II) in terms of chaperone‐like activity and structure. In this study mutant H119G of rat lens αB‐crystalin was cloned and expressed to investigate whether His119 is the coordination binding site. Copper and zinc at 1 mM concentration significantly increase the chaperone‐like activity in wild type αB‐crystalin, whereas zinc, copper and magnesium at 1 mM reduced the activity of H119G significantly. The results from chaperone‐like activity, ANS fluorescence measurement and Far‐and Near‐UV CD studies suggest that the replacement of His119 with Glycine resulted in a conformational and minor environmental changes that decrease chaperone‐like activity in the presence of divalent ions suggested that His119 was a crucial binding site for Cu(II) and Zn(II), which was similar to our previous study results of His18. Both results together suggest that His18 and His119 coordinates each other for the binding site of Cu(II) and Zn(II) in terms of improving the chaperone‐like activity and stability of crystallin/metal ion complex.     

Direct Monitoring of γ‐Glutamyl Transpeptidase Activity In Vivo Using a Hyperpolarized 13C‐Labeled Molecular Probe

The γ‐glutamyl transpeptidase (GGT) enzyme plays a central role in glutathione homeostasis. Direct detection of GGT activity could provide critical information for the diagnosis of several pathologies. We propose a new molecular probe, γ‐Glu‐[1‐¹³C]Gly, for monitoring GGT activity in vivo by hyperpolarized (HP) ¹³C magnetic resonance (MR). The properties of γ‐Glu‐[1‐¹³C]Gly are suitable for in vivo HP ¹³C metabolic analysis since the chemical shift between γ‐Glu‐[1‐¹³C]Gly and its metabolic product, [1‐¹³C]Gly, is large (4.3 ppm) and the T₁ of both compounds is relatively long (30 s and 45 s, respectively, in H₂O at 9.4 T). We also demonstrate that γ‐Glu‐[1‐¹³C]Gly is highly sensitive to in vivo modulation of GGT activity induced by the inhibitor acivicin.     

Novel water soluble bis(μ‐chloro) bridged Cu(II) binuclear and mononuclear complexes: Synthesis,characterization and biological evaluation

A water soluble chloro bridged binuclear copper(II) complex (3) and mononuclear complex (4) have been synthesized from chloro substituted 2‐oxo‐1,2‐dihydroquinolin‐3‐yl‐methylene‐2 hydroxybenzohydrazide 1 and 2 and CuCl₂·2H₂O. The structures of the complexes have been determined by single crystal X‐ray diffraction. The binding interactions of the ligands and complexes with CT‐DNA and protein have been evaluated by absorption and emission spectroscopic method. CT‐DNA and ethidium bromide (EB) competitive studies revealed that the compounds could interact with CT‐DNA through intercalation binding mode. Interactions of the compounds with BSA were also studied by UV−visible, fluorescence and synchronous fluorescence spectroscopic methods which showed that the compounds had a strong binding affinity with BSA through static quenching process. The cytotoxic effect of the compounds examined on cancer cell lines, such as A549 (lung cancer) and MCF7 (breast cancer) cell lines showed that all four compounds exhibited substantial cytotoxic activity.     

Synthesis,characterization and biological evaluation of a cobalt(II) complex with 5‐chloro‐8‐hydroxyquinoline as anticancer agent

A new cobalt(II) complex ( 1 ) of 5‐chloro‐8‐hydroxyquinoline was prepared and structurally characterized using infrared spectroscopy, electrospray ionization mass spectrometry, elemental analysis, single‐crystal X‐ray diffraction as well as powder X‐ray diffraction. Its biological activities including DNA binding and anticancer activity were investigated. The DNA binding study of complex 1 suggested that it interacted with calf thymus DNA mainly via an intercalative binding mode. The in vitro anticancer activity of complex 1 was screened against a series of tumor cell lines as well as the normal liver cell line HL‐7702 using MTT assay. complex 1 showed much higher cytotoxicity than corresponding metal salt and ligand towards the five tested tumor cell lines, in which T‐24 was the most sensitive tumor cell line towards 1, with IC₅₀ value of 7.04 ± 0.06 μM. complex 1 was found to greatly induce cell cycle arrest in T‐24 cells at S phase, and consequently to induce cell apoptosis in a dose‐dependent mode suggested by cell apoptosis analysis via Hoechst 33258 and acridine orange/ethidium bromide staining assays. The cell apoptosis mechanism of 1 was studied targeting the mitochondrion‐mediated pathway, since the apoptotic mechanism in the T‐24 cells treated by 1 was investigated by reactive oxygen species (ROS) detection, intracellular calcium concentration measurement and caspase‐9/3 activity assay. The results suggested that the cell apoptosis induced by 1 was closely related to the loss of mitochondrial membrane potential, ROS production and enhancement of intracellular [Ca²⁺], which would trigger the caspase‐9/3 activation via a mitochondrial dysfunction pathway. Copyright © 2016 John Wiley & Sons, Ltd.     

Carbophilic 3‐Component Cascades: Access to Complex Bioactive Cyclopropyl Diindolylmethanes

Naturally occurring indole‐3‐carbinol and 3,3‐diindolylmethane show bioactivity in a number of disparate disease areas, including cancer, prompting substantial synthetic analogue activity. We describe a new approach to highly functionalised derivatives that starts from allene gas and proceeds via the combination of a three‐component Pd⁰‐catalysed cascade with a one‐pot, three‐component carbophilic Pt^II cascade linked to a stereoselective acid‐catalysed Mannich–Michael reaction that generates complex cyclopropyl diindolylmethanes which show selective activity against prostate cancer cell lines.     

Histidine‐Rich Oligopeptides To Lessen Copper‐Mediated Amyloid‐β Toxicity

Brain copper imbalance plays an important role in amyloid‐β aggregation, tau hyperphosphorylation, and neurotoxicity observed in Alzheimer's disease (AD). Therefore, the administration of biocompatible metal‐binding agents may offer a potential therapeutic solution to target mislocalized copper ions and restore metallostasis. Histidine‐containing peptides and proteins are excellent metal binders and are found in many natural systems. The design of short peptides showing optimal binding properties represents a promising approach to capture and redistribute mislocalized metal ions, mainly due to their biocompatibility, ease of synthesis, and the possibility of fine‐tuning their metal‐binding affinities in order to suppress unwanted competitive binding with copper‐containing proteins. In the present study, three peptides, namely HWH , HK^CH , and HAH , have been designed with the objective of reducing copper toxicity in AD. These tripeptides form highly stable albumin‐like complexes, showing higher affinity for Cu^II than that of Aβ(1‐40). Furthermore, HWH , HK^CH , and HAH act as very efficient inhibitors of copper‐mediated reactive oxygen species (ROS) generation and prevent the copper‐induced overproduction of toxic oligomers in the initial steps of amyloid aggregation in the presence of Cu^II ions. These tripeptides, and more generally small peptides including the sequence His‐Xaa‐His at the N‐terminus, may therefore be considered as promising motifs for the future development of new and efficient anti‐Alzheimer drugs.     

Synthesis,characterization and anticancer activity of new palladacycles derived from chiral α‐diimines

Optically pure α‐diimines quantitatively obtained in solvent‐free conditions starting from 2,3‐butanedione and (S)‐(?)‐1‐phenylethylamine and (S)‐(?)‐1‐(4‐methylphenyl)ethylamine, respectively, yielded the new chiral mono‐Pd complexes 2a–b, which have been partly characterized by IR, ¹H‐ and ¹³C‐NMR spectroscopies along with MS‐FAB⁺ spectrometry. The crystal and molecular structure for palladacycle 2a has been fully confirmed by single‐crystal X‐ray studies. Studies in vitro of 2a–b have displayed growth inhibition against different classes of cancer: leukemia (K‐562 CML), colon cancer (HCT‐15), breast cancer (MCF‐7), central nervous system (U‐251 Glio) and prostate cancer (PC‐3) cell lines. Copyright © 2009 John Wiley & Sons, Ltd.     

Development of Zinc‐Specific iCEST MRI as an Imaging Biomarker for Prostate Cancer

The healthy prostate contains the highest concentration of mobile zinc in the body. As this level decreases dramatically during the initial development of prostate cancer, in vivo detection of prostate zinc content may be applied for diagnosis of prostate cancer. Using ¹⁹F ion chemical exchange saturation transfer magnetic resonance imaging (iCEST MRI) and TF‐BAPTA as a fluorinated Zn‐binding probe with micromolar sensitivity, we show that iCEST MRI is able to differentiate between normal and malignant prostate cells with a 10‐fold difference in contrast following glucose‐stimulated zinc secretion in vitro. The iCEST signal decreased in normal prostate cells upon downregulation of the ZIP1 zinc transporter. In vivo, using an orthotopic prostate cancer mouse model and a transgenic adenocarcinoma of the mouse prostate (TRAMP) model, a gradual decrease of >300 % in iCEST contrast following the transition of normal prostate epithelial cells to cancer cells was detected.     

Efficient Synthesis of Some New 1,3,4‐Thiadiazoles and 1,2,4‐Triazoles Linked to Pyrazolylcoumarin Ring System as Potent 5α‐Reductase Inhibitors

The current study in this article concerned with construction of five‐membered heterocycles with multiple heteroatoms as nitrogen and sulfur from readily available starting materials and reagents. Treatment of 1‐(2‐oxo‐2H‐chromene‐3‐carbonyl)‐3‐phenyl‐1H‐pyrazol‐5(4H)‐one with each of phenylisothiocyanate in alcoholic potassium hydroxide and carbon disulfide in basic medium gave rise to a thioanilide and methylthio derivatives, respectively. Treatment of the latter compounds with a variety of hydrazonoyl halides resulted in construction of thiadiazole moiety linked to pyrazole ring. Furthermore, triazole derivatives were synthesized from the thioanilide derivative through its reaction with methyl iodide followed by reaction with hydrazonoyl halides. 5α‐Reductase inhibition activity for the prepared compounds was investigated against the reference drug anastrozole, and the results showed that the inhibition activity of compounds 5g and 11g is more potent than anastrozole. Also compounds bearing triazole moiety is more potent than compounds bearing thiadiazole one. Moreover, the anti‐prostate cancer screening anti‐androgenic bioassay in human prostate cancer cells for the tested compounds was evaluated, and the results showed great inhibition growth and potential antiandrogens.     

Synthesis,Characterization, Crystal Structure,and Biological Activities of Transition Metal Complexes with 1‐Phenyl‐3‐methyl‐5‐hydroxypyrazole‐4‐methylene‐8′‐quinolineimine

The Schiff base ligand, 1‐phenyl‐3‐methyl‐5‐hydroxypyrazole‐4‐methylene‐8′‐quinolineimine, and its Cu^II, Zn^II, and Ni^II complexes were synthesized and characterized. The crystal structure of the Zn^II complex was determined by single‐crystal X‐ray diffraction, indicating that the metal ions and Schiff base ligand can form mononuclear six‐coordination complexes with 1:1 metal‐to‐ligand stoichiometry at the metal ions as centers. The binding mechanism and affinity of the ligand and its metal complexes to calf thymus DNA (CT DNA) were investigated by UV/Vis spectroscopy, fluorescence titration spectroscopy, EB displacement experiments, and viscosity measurements, indicating that the free ligand and its metal complexes can bind to DNA via an intercalation mode with the binding constants at the order of magnitude of 105–106 M ^–1, and the metal complexes can bind to DNA more strongly than the free ligand alone. In addition, antioxidant activities of the ligand and its metal complexes were investigated through scavenging effects for hydroxyl radical in vitro, indicating that the compounds show stronger antioxidant activities than some standard antioxidants, such as mannitol. The ligand and its metal complexes were subjected to cytotoxic tests, and experimental results indicated that the metal complexes show significant cytotoxic activity against lung cancer A 549 cells.     

Synthesis,structure, characterization and biological evaluation of 3‐substituted 1‐pyridin‐2‐ylimidazo[1,5‐a]pyridine‐based copper(I)–phosphine complexes for anticancer drug screening

Copper(I) complexes of the types [Cu(N–N)(PPh₃)₂]NO₃ (LC41–LC44) and [Cu(N–N)(PPh₃)(NO₃)] (LC45) carrying 3‐substituted 1‐pyridine‐2‐ylimidazo[1,5‐a]pyridine (N–N) derivatives and triphenylphosphine (PPh₃) ligands have been prepared. The synthesized copper(I)–phosphine complexes were fully characterized by NMR, IR, ESI‐MS and UV–visible spectroscopy as well as by cyclic voltammetry. Selected structures such as LC42, LC43 and LC45 were additionally analysed by single‐crystal X‐ray method, which show that copper(I) centre adopts a highly distorted tetrahedral geometry. The ¹H and ¹³C NMR spectral data of the complexes throw light on the nature of metal–ligand bonding. They display dπ–π* metal‐to‐ligand charge transfer (MLCT) transition and show quasireversible Cu^I/Cu^II metal oxidation. Among the copper(I)–phosphine complexes, LC41–LC44 exhibit moderate cytotoxicity (IC₅₀: 24 h, 67–74 μM; 48 h, 58–70 μM) against human lung epithelial adenocarcinoma A549 cells, whereas LC45 displays the best activity (IC₅₀: 24 h, 42 μM; 48 h, 34 μM) for A549 cancer cell line, which is better than that of the commercial antitumor drug cisplatin. All the complexes also displayed excellent selectivity by being relatively inactive against the human lung epithelial L132 normal cell line with selectivity index (SI) values ranging from 3.4 to 7.4. The complexes block cell cycle progression of A549 cells in G₀/G₁ phase. FACSVerse analyses are suggestive of reactive oxygen species (ROS) generation and apoptotic cell death induced by the LC41, LC43 and LC45. The induction of apoptosis in A549 cells was shown by Annexin V with propidium iodide (PI) and 4′,6‐diamidino‐2‐phenylindole (DAPI) staining methods and established the ability of LC41, LC43 and LC45 to accumulate in the cell nuclei.     

Synthesis and In Vitro Anticancer Activity of Novel 1,3,4‐Oxadiazole‐Linked 1,2,3‐Triazole/Isoxazole Hybrids

A series of new 1,3,4‐oxadiazole‐linked 1,2,3‐triazole/isoxazole derivatives were designed and synthesized. All the synthesized compounds were screened for in vitro anticancer activity against four human cancer cells: HeLa (cervical), MDA‐MB‐231 (breast), DU‐145 (prostate), and HEPG2 (liver). Among 17 compounds tested, 7a , 7c , and 7d showed potent activity toward four cell lines.     

Structural Studies and Anticancer Activity of a Novel Class of β‐Peptides

Functionalized oligomeric organic compounds with well‐defined β‐proline scaffold have been synthesized by a cycloadditive oligomerization approach in racemic and enantiopure forms. The structure of the novel β‐peptides was investigated by NMR spectroscopic and X‐ray methods determining the conformational shapes of the β‐proline oligomers in solution and solid states. The main structural elements subject to conformational switches are β‐peptide bonds between 5‐arylpyrrolidine‐2‐carboxylic acid units existing in Z/E configurations. The whole library of short β‐peptides and intermediate acrylamides has been tested on antiproliferative activity towards the hormone‐refractory prostate cancer cell line PC‐3 revealing several oligomeric compounds with low micromolar and submicromolar activities. Bromine‐substituted dimeric and trimeric acrylamides induced caspase‐dependent apoptosis of PC‐3 cells through cell‐cycle arrest and mitochondrial damage.     

Ferrocene‐substituted 3,3′‐diindolylmethanes with improved anticancer activity

A series of ferrocene‐substituted derivatives ( 2a , 2b , 2c , 2d , 2e , 2f , 2g ) of the known drug 3,3′‐diindolylmethane ( DIM ) were prepared and tested for their in vitro antitumor activity. The derivatives 2a (featuring indole moiety), 2b (featuring 2‐methylindole moiety) and 2f (featuring 5‐nitroindole moiety) were growth‐inhibiting in vitro at lower concentrations than DIM in various tumor cells including pancreas cancer (BcPC‐3), three DIM‐resistant cancer cell lines (518 A2, KB‐V1/Vbl, HT‐29), triple‐negative breast cancer (MDA‐MB‐231) and prostate cancer (PC‐3). Derivatives 2a , 2b and 2f were the most active compounds of this series, qualifying as drug candidates for various cancer diseases. Copyright © 2016 John Wiley & Sons, Ltd.     

A mononuclear copper(II) complex containing benzimidazole and pyridyl ligands: Synthesis,characterization, and antiproliferative activity against human cancer cells

Metal complexes are recently being hybridized with different moieties to discover new drugs due to their advantageous attributes. Among the metals, copper is a good one to synthesize a metal complex due to its being endogenous, redox and DNA cleavage potential, reported anti-cancer efficacies and selective permeability for cancer cells. In this study, first we synthesized a new copper (II) complex and determined its toxic doses on NIH/3T3 normal fibroblast cells, SPC212 mesothelioma and DU145 prostate cancer cells. Then, we ascertained anti-proliferative, apoptotic, morphological, oxidative and endoplasmic reticulum (ER) stress inducing effects of these newly synthesized compounds on DU145 prostate cancer cells. A novel Copper(II)/1-(4-(trifluoromethyl)benzyl)-1H-benzimidazole/2,2′-bipyridyl complex was synthesized and mainly characterized by single crystal X-ray diffraction analysis. Anti-proliferative effect of copper(II) complex was gauged by MTT. Oxidative and ER stress were evaluated by ELISA and Western blot. The morphological effect was examined by microscope analysis. Besides, immunocytochemistry of Bax, a pro-apoptotic protein and PCNA, a proliferation marker protein was performed. As a result, the inhibitory effect of newly synthesized substance was superior to the chemicals from which it was synthesized. Its IC₅₀s against DU145 were 37.0, 21.1 and 10.0 µM for 24, 48 and 72 h-treatments, respectively. Oxidative and ER stress increased after treatment. In microscopy, we observed apoptotic hallmarks like nuclear condensation, cellular shrinkage and membrane blebbings. In immunochemistry, increased Bax and decreased PCNA were apparent. Copper(II) complex with its relatively low IC₅₀ can also be tested on other cancer and normal cell lines.     

Synthesis and In Vitro Anticancer Evaluation of Symmetrically Bridged 1,3‐thiazine Derivatives

A series of bis‐1,3‐thiazine derivatives 3a–o were synthesized from the condensation reactions of symmetric dialdehydes 1a–c possessing aliphatic ether spacer units with 3‐substituted‐amino‐2‐cyano‐3‐mercaptoacrylamides 2a–e . The chemical structures of the products were fully characterized by using different spectroscopic techniques, such as ¹H NMR, ¹³C NMR, IR, electron impact mass spectrometry, and elemental analysis. Compounds 3a , 3f , and 3k underwent ring opening followed by recyclization and alkylation in basic medium to afford bis‐pyrimidinones 4a–c and 5a–c . The anticancer potential of the new bis‐1,3‐thiazines was assessed in vitro against six different human cell lines, including lung A549, colon HCT116, breast MCF‐7, prostate PC3, liver HepG2, and normal melanocyte HFB4. The results revealed a potent activity of compounds 3e and 3k against breast and liver cancer cell lines in comparison with the reference drug doxorubicin with no noticeable toxicity on normal cells.