Structure‐Based Design of a Monosaccharide Ligand Targeting Galectin‐8

Galectin‐8 is a β‐galactoside‐recognising protein that has a role in the regulation of bone remodelling and is an emerging new target for tackling diseases with associated bone loss. We have designed and synthesised methyl 3‐O‐[1‐carboxyethyl]‐β‐d ‐galactopyranoside (compound 6 ) as a ligand to target the N‐terminal domain of galectin‐8 (galectin‐8N). Our design involved molecular dynamics (MD) simulations that predicted 6 to mimic the interactions made by the galactose ring as well as the carboxylic acid group of 3′‐O‐sialylated lactose (3′‐SiaLac), with galectin‐8N. Isothermal titration calorimetry (ITC) determined that the binding affinity of galectin‐8N for 6 was 32.8 μm , whereas no significant affinity was detected for the C‐terminal domain of galectin‐8 (galectin‐8C). The crystal structure of the galectin‐8N– 6 complex validated the predicted binding conformation and revealed the exact protein–ligand interactions that involve evolutionarily conserved amino acids of galectin and also those unique to galectin‐8N for recognition. Overall, we have initiated and demonstrated a rational ligand design campaign to develop a monosaccharide‐based scaffold as a binder of galectin‐8.     

Galectin‐3‐Binding Glycomimetics that Strongly Reduce Bleomycin‐Induced Lung Fibrosis and Modulate Intracellular Glycan Recognition

Discovery of glycan‐competitive galectin‐3‐binding compounds that attenuate lung fibrosis in a murine model and that block intracellular galectin‐3 accumulation at damaged vesicles, hence revealing galectin‐3–glycan interactions involved in fibrosis progression and in intracellular galectin‐3 activities, is reported. 3,3′‐Bis‐(4‐aryltriazol‐1‐yl)thiodigalactosides were synthesized and evaluated as antagonists of galectin‐1, ‐2, ‐3, and ‐4 N‐terminal, ‐4 C‐terminal, ‐7 and ‐8 N‐terminal, ‐9 N‐terminal, and ‐9 C‐terminal domains. Compounds displaying low‐nanomolar affinities for galectins‐1 and ‐3 were identified in a competitive fluorescence anisotropy assay. X‐ray structural analysis of selected compounds in complex with galectin‐3, together with galectin‐3 mutant binding experiments, revealed that both the aryltriazolyl moieties and fluoro substituents on the compounds are involved in key interactions responsible for exceptional affinities towards galectin‐3. The most potent galectin‐3 antagonist was demonstrated to act in an assay monitoring galectin‐3 accumulation upon amitriptyline‐induced vesicle damage, visualizing a biochemically/medically relevant intracellular lectin–carbohydrate binding event and that it can be blocked by a small molecule. The same antagonist administered intratracheally attenuated bleomycin‐induced pulmonary fibrosis in a mouse model with a dose/response profile comparing favorably with that of oral administration of the marketed antifibrotic compound pirfenidone.     

Exploring the Structural Space of the Galectin‐1–Ligand Interaction

Galectin‐1 is a tumor‐associated protein recognizing the Galβ1‐4GlcNAc motif of cell‐surface glycoconjugates. Herein, we report the stepwise expansion of a multifunctional natural scaffold based on N‐acetyllactosamine (LacNAc). We obtained a LacNAc mimetic equipped with an alkynyl function on the 3′‐hydroxy group of the disaccharide facing towards a binding pocket adjacent to the carbohydrate‐recognition domain. It served as an anchor motif for further expansion by the Sharpless–Huisgen–Meldal reaction, which resulted in ligands with a binding mode almost identical to that of the natural carbohydrate template. X‐ray crystallography provided a structural understanding of the galectin‐1–ligand interactions. The results of this study enable the development of bespoke ligands for members of the galectin target family.     

Investigation into the Feasibility of Thioditaloside as a Novel Scaffold for Galectin‐3‐Specific Inhibitors

Galectin‐3 is extensively involved in metabolic and disease processes, such as cancer metastasis, thus giving impetus for the design of specific inhibitors targeting this β‐galactose‐binding protein. Thiodigalactoside (TDG) presents a scaffold for construction of galectin inhibitors, and its inhibition of galectin‐1 has already demonstrated beneficial effects as an adjuvant with vaccine immunotherapy, thereby improving the survival outcome of tumour‐challenged mice. A novel approach—replacing galactose with its C2 epimer, talose—offers an alternative framework, as extensions at C2 permit exploitation of a galectin‐3‐specific binding groove, thereby facilitating the design of selective inhibitors. We report the synthesis of thioditaloside (TDT) and crystal structures of the galectin‐3 carbohydrate recognition domain in complexes with TDT and TDG. The different abilities of galactose and talose to anchor to the protein correlate with molecular dynamics studies, likely explaining the relative disaccharide binding affinities. The feasibility of a TDT scaffold to enable access to a particular galectin‐3 binding groove and the need for modifications to optimise such a scaffold for use in the design of potent and selective inhibitors are assessed.     

Synthesis and Evaluation of New Thiodigalactoside‐Based Chemical Probes to Label Galectin‐3

Light up galectin: Photoprobes based on thiodigalactoside were prepared for galectin‐3, a lectin linked to cancer. The probes contained either benzophenone or acetophenone moieties as the photolabel for covalent attachment to the protein. One particular probe labeled galectin‐3 selectively, even in the presence of cell lysate.

     

Gadolinium‐conjugated FA‐PEG‐PAMAM‐COOH nanoparticles as potential tumor‐targeted circulation‐prolonged macromolecular MRI contrast agents

The aim of research is to develop potential tumor‐targeted circulation‐prolonged macromolecular magnetic resonance imaging (MRI) contrast agents without the use of low molecular gadolinium (Gd) ligands. The contrast agents were based on polymer–metal complex nanoparticles with controllable particle size to achieve the active and passive tumor‐targeted potential. In particular, poly (amidoamine) (PAMAM) dendrimer with 32 carboxylic groups was modified with folate‐conjugated poly (ethyleneglycol) amine (FA‐PEG‐NH₂, M_w: 2 k and 4 kDa). FA‐PEG‐PAMAM‐Gd macromolecular MRI contrast agents were prepared by the complex reaction between the carboxylic groups in PAMAM and GdCl₃. The structure of FA‐PEG‐PAMAM‐COOH was confirmed by nuclear magnetic resonance (¹H‐NMR), Fourier transform infrared (FTIR) spectra, and electrospray ionization mass spectra (ESI‐MS). The mass percentage content of Gd (III) in FA‐PEG‐PAMAM‐Gd was measured by inductively coupled plasma‐atomic emission spectrometer (ICP‐AES). The sizes of these nanoparticles were about 70 nm measured by transmission electron microscopy, suggestion of their passive targeting potential to tumor tissue. In comparison with clinically available small molecular Gadopentetate dimeglumine, FA‐PEG‐PAMAM‐Gd showed comparable cytotoxicity and higher relaxation rate, suggestion of their great potential as tumor‐targeted nanosized macromolecular MRI contrast agents due to the overexpressed FA receptor in human tumor cell surfaces. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Acetylation of dendrimer‐entrapped gold nanoparticles: Synthesis,stability, and X‐ray attenuation properties

Functionalized dendrimer‐entrapped gold nanoparticles (Au DENPs) are of scientific and technological interest in biomedical applications. In this study, Au DENPs prepared with amine‐terminated generation 5 (G5) poly(amido amine) dendrimers as templates were subjected to acetylation to neutralize the positive surface charge of the particles. By varying the molar ratio of Au salt to G5 dendrimer, we prepared acetylated Au DENPs with a size range of 2–4 nm. Meanwhile, we attempted to add glucose to the dialysis liquid of the acetylated Au DENPs to prevent possible particle aggregation after lyophilization. The acetylated Au DENPs with different compositions (Au salt/dendrimer molar ratios) were characterized with ¹H‐NMR, transmission electron microscopy, ultraviolet–visible (UV–vis) spectrometry, and ζ‐potential measurements. We show that when the molar ratio of Au salt to dendrimer was equal to or larger than 75:1, the acetylated Au DENPs showed a significant aggregation after lyophilization, and the addition of glucose was able to preserve the colloidal stability of the particles. X‐ray absorption measurements showed that the attenuation of the acetylated Au DENPs was much higher than that of the iodine‐based contrast agent at the same molar concentration of the active element (Au vs iodine). In addition, the acetylated Au DENPs enabled X‐ray computed tomography (CT) imaging of mice after intravenous injection of the particles. These findings suggest a great potential for acetylated Au DENPs as a promising contrast agent for CT imaging applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Lecithin‐enhanced biotransformation of cholesterol to androsta‐1,4‐diene‐3,17‐dione and androsta‐4‐ene‐3,17‐dione

A biotransformation process using Mycobacterium sp was studied for androsta‐1, 4‐diene‐3,17‐dione (ADD) and androsta‐4‐ene‐3,17‐dione (AD) production from cholesterol. Cholesterol has a poor solubility in water (～1.8 mg dm^?3 at 25 °C), which makes it difficult to use as the substrate for biotransformation. Lecithin is a mixture of phospholipids of phosphatidylcholine (PC) and phosphatidylethanolamine (PE), which behave like surfactants and can form planar bi‐layer structures in an aqueous medium. Therefore, a small amount of lecithin (<1 g dm^?3) can be used to form stable colloids with cholesterol at a relatively high concentration (20 g dm^?3) in water. In this work, an energy density of 1000 J cm^?3 from sonication was provided to overcome the self‐association of cholesterol and to generate a stable lecithin–cholesterol suspension that could be used for enhanced biotransformation. The lecithin–cholesterol suspension was stable and could withstand typical autoclaving conditions (121 °C, 15 psig, 20 min). In contrast to conventional surfactants, such as Tween 80, that are commonly used to help solubilize cholesterol, lecithin did not change the surface tension of the aqueous solution nor cause any significant foaming problem. Lecithin was also biocompatible and showed no adverse effect on cell growth. Compared with the medium with Tween 80 as the cholesterol‐solubilizing agent, lecithin greatly improved the biotransformation process in regard to its final product yield (～59% w/w), productivity (0.127–0.346 g dm^?3 day^?1), ADD/AD ratio (6.7–8), as well as the long‐term process stability. Cells can be reused in repeated batch fermentations for up to seven consecutive batches, but then lose their bioactivity due to aging problems, possibly caused by product inhibition and nutrient depletion. © 2002 Society of Chemical Industry     

Hetero‐bivalent GLP‐1/Glibenclamide for Targeting Pancreatic β‐Cells

G protein‐coupled receptor (GPCR) cell signalling cascades are initiated upon binding of a specific agonist ligand to its cell surface receptor. Linking multiple heterologous ligands that simultaneously bind and potentially link different receptors on the cell surface is a unique approach to modulate cell responses. Moreover, if the target receptors are selected based on analysis of cell‐specific expression of a receptor combination, then the linked binding elements might provide enhanced specificity of targeting the cell type of interest, that is, only to cells that express the complementary receptors. Two receptors whose expression is relatively specific (in combination) to insulin‐secreting pancreatic β‐cells are the sulfonylurea‐1 (SUR1) and the glucagon‐like peptide‐1 (GLP‐1) receptors. A heterobivalent ligand was assembled from the active fragment of GLP‐1 (7–36 GLP‐1) and glibenclamide, a small organic ligand for SUR1. The synthetic construct was labelled with Cy5 or europium chelated in DTPA to evaluate binding to β‐cells, by using fluorescence microscopy or time‐resolved saturation and competition binding assays, respectively. Once the ligand binds to β‐cells, it is rapidly capped and presumably removed from the cell surface by endocytosis. The bivalent ligand had an affinity approximately fivefold higher than monomeric europium‐labelled GLP‐1, likely a result of cooperative binding to the complementary receptors on the βTC3 cells. The high‐affinity binding was lost in the presence of either unlabelled monomer, thus demonstrating that interaction with both receptors is required for the enhanced binding at low concentrations. Importantly, bivalent enhancement was accomplished in a cell system with physiological levels of expression of the complementary receptors, thus indicating that this approach might be applicable for β‐cell targeting in vivo.     

Anticancer Potency Studies of Coordination Driven Self‐Assembled Arene–Ru‐Based Metalla‐Bowls

New tetranuclear cationic metalla‐bowls 5 – 7 with the general formula [Ru₄(p‐cymene)₄(N∩N)₂(OO∩OO)₂]⁴⁺ (N∩N=2,6‐bis(N‐(4‐pyridyl carbamoyl)pyridine, OO∩OO=2,5‐dihydroxy‐1,4‐benzoquinonato ( 5 ), OO∩OO=5,8‐dioxydo‐1,4‐naphthaquinonato ( 6 ), OO∩OO=hoxonato ( 7 )) were prepared by the reaction of the respective dinuclear ruthenium complexes 2 – 4 with a bispyridine amide donor ligand 1 in methanol in the presence of AgO₃SCF₃.These new molecular metalla‐bowls were fully characterized by analytical techniques including elemental analysis as well as ¹H and ¹³C NMR and HR‐ESI‐MS spectroscopy. The structure of metalla‐bowl 6 was determined from X‐ray crystal diffraction data. A UV/visible study was also carried out for the entire suite of new complexes. As with recent studies of similar arene–Ru complexes, the inhibition of cell growth by metalla‐bowls was established against SK‐hep‐1 (liver cancer), AGS (gastric cancer), and HCT‐15 (colorectal cancer) human cancer cell lines. Inhibition of cell growth by 6 was found to be considerably stronger against all cancer cell lines than the anticancer drugs, doxorubicin and cisplatin. In particular, in colorectal cancer cells, expression of the cancer suppressor genes APC and p53 was increased following exposure to 6 .     

Synthesis,characterization and (electro)chemical polymerization of triphenylamine‐end‐functionalized poly(ε‐caprolactone)

Triphenylamine‐based oligomers and polymers with linear, hyperbranched, star‐shaped or dendrimer architectures have been synthesized and studied due to their interesting electro‐optical properties. In many cases insoluble materials are obtained. In this study, we report the synthesis of grafted polytriphenylamine by chemical and electrochemical polymerization of triphenylamine‐end‐functionalized poly(ε‐caprolactone). Functionalized ε‐caprolactone oligomers were obtained by ring‐opening polymerization of ε‐caprolactone initiated by 4‐hydroxymethyltriphenylamine/stannous octanoate (tin 2‐ethylhexanoate). The ring‐opening polymerization of ε‐caprolactone using 4‐hydroxymethyltriphenylamine/stannous octanoate as initiating system provided ε‐caprolactone oligomers, with well‐defined molecular weights, containing a triphenylamine terminal group. Chemical and electrochemical coupling oxidation of the triphenylamine ends allowed the formulation of polyarylamines with ε‐caprolactone oligomers as grafts. Graft copolymers with an aryleneamine backbone and short poly(ε‐caprolactone) grafts were obtained by (electro)chemical oxidation of oligomers containing triphenylamine terminal groups. Copyright © 2009 Society of Chemical Industry     

An Engineered Biocatalyst for the Synthesis of Glycoconjugates: Utilization of β1,3‐N‐Acetyl‐D‐glucosaminyltransferase from Streptococcus agalactiae Type Ia Expressed in Escherichia coli as a Fusion with Maltose‐Binding Protein

A fusion protein composed of β1,3‐N‐acetyl‐D ‐glucosaminyltransferase (β1,3‐GlcNAcT) from Streptococcus agalactiae type Ia and maltose‐binding protein (MBP) was produced in Escherichia coli as a soluble and highly active form. Although this fusion protein (MBP‐β1,3‐GlcNAcT) did not show any sugar‐elongation activity to some simple low‐molecular weight acceptor substrates such as galactose, Galβ(1→4)Glc (lactose), Galβ(1→4)GlcNAc (N‐acetyllactosamine), Galβ(1→4)GlcNAcβ(1→3)Galβ(1→4)Glc (lacto‐N‐tetraose), and Galβ(1→4)GlcβCer (lactosylceramide, LacCer), the multivalent glycopolymer having LacCer‐mimic branches (LacCer mimic polymer, LacCer primer) was found to be an excellent acceptor substrate for the introduction of a β‐GlcNAc residue at the O‐3 position of the non‐reducing galactose moiety by this engineered enzyme. Subsequently, the polymer having GlcNAcβ(1→3)Galβ(1→4)Glc was subjected to further enzymatic modifications by using recombinant β1,4‐D ‐galactosyltransferase (β1,4‐GalT), α2,3‐sialyltransferase (α2,3‐SiaT), α1,3‐L ‐fucosyltransferase (α1,3‐FucT), and ceramide glycanase (CGase) to afford a biologically important ganglioside; Neu5Aα(2→3)Galβ(1→4)[Fucα(1→3)]GlcNAcβ(1→3)Galβ(1→4)GlcCerα(IV3Neu5Acα,III3Fucα‐nLc4Cer) in 40% yield (4 steps). Interestingly, it was suggested that MBP‐β1,3‐GlcNAcT could also catalyze a glycosylation reaction of the LacCer mimic polymer with N‐acetyl‐D ‐galactosamine served from UDP‐GalNAc to afford a polymer carrying trisaccharide branches, GalNAcβ(1→3)Galβ(1→4)Glc. The versatility of the MBP‐β1,3‐GlcNAcT in the practical synthesis was preliminarily demonstrated by applying this fusion protein as an immobilized biocatalyst displayed on the amylose resin which is known as a solid support showing potent binding‐affinity with MBP.     

Microdomain Formation Controls Spatiotemporal Dynamics of Cell‐Surface Glycoproteins

The effect of galectin‐mediated microdomain formation on the spatiotemporal dynamics of glycosylated membrane proteins in human microvascular endothelial cells (HMEC‐1) was studied qualitatively and quantitatively by high‐resolution fluorescence microscopy and artificially mimicked by metabolic glycoprotein engineering. Two types of membrane proteins, sialic acid‐bearing proteins (SABPs) and mucin‐type proteins (MTPs), were investigated. For visualization they were metabolically labeled with azido sugars and then coupled to a cyclooctyne‐conjugated fluorescent dye by click chemistry. Both spatial (diffusion) and temporal (residence time) dynamics of SABPs and MTPs on the membrane were investigated after treatment with exogenous galectin‐1 or ‐3. Strong effects of galectin‐mediated lattice formation were observed for MTPs (decreased spatial mobility), but not for SABPs. Lattice formation also strongly decreased the turnover of MTPs (increased residence time on the cell membrane). The effects of galectin‐mediated crosslinking was accurately mimicked by streptavidin‐mediated crosslinking of biotin‐tagged glycoproteins and verified by single‐molecule tracking. This technique allows the induction of crosslinking of membrane proteins under precisely controlled conditions, thereby influencing membrane residence time and the spatial dynamics of glycans on the cell membrane in a controlled way.     

Structural Determinants of the Selectivity of 3‐Benzyluracil‐1‐acetic Acids toward Human Enzymes Aldose Reductase and AKR1B10

The human enzymes aldose reductase (AR) and AKR1B10 have been thoroughly explored in terms of their roles in diabetes, inflammatory disorders, and cancer. In this study we identified two new lead compounds, 2‐(3‐(4‐chloro‐3‐nitrobenzyl)‐2,4‐dioxo‐3,4‐dihydropyrimidin‐1(2H)‐yl)acetic acid (JF0048, 3 ) and 2‐(2,4‐dioxo‐3‐(2,3,4,5‐tetrabromo‐6‐methoxybenzyl)‐3,4‐dihydropyrimidin‐1(2H)‐yl)acetic acid (JF0049, 4 ), which selectively target these enzymes. Although 3 and 4 share the 3‐benzyluracil‐1‐acetic acid scaffold, they have different substituents in their aryl moieties. Inhibition studies along with thermodynamic and structural characterizations of both enzymes revealed that the chloronitrobenzyl moiety of compound 3 can open the AR specificity pocket but not that of the AKR1B10 cognate. In contrast, the larger atoms at the ortho and/or meta positions of compound 4 prevent the AR specificity pocket from opening due to steric hindrance and provide a tighter fit to the AKR1B10 inhibitor binding pocket, probably enhanced by the displacement of a disordered water molecule trapped in a hydrophobic subpocket, creating an enthalpic signature. Furthermore, this selectivity also occurs in the cell, which enables the development of a more efficient drug design strategy: compound 3 prevents sorbitol accumulation in human retinal ARPE‐19 cells, whereas 4 stops proliferation in human lung cancer NCI‐H460 cells.     

Thin Films Bearing Conjugated Polymer Nanoparticles Fabricated by Microliter‐Scale Layer‐by‐Layer Deposition

A conjugated polymer, poly(9,9‐bis(6‐bromohexyl)‐9H‐fluorene‐alt‐1,4‐phenylene), is synthesized, converted to nanoparticles via a nanoprecipitation process, and utilized to fabricate thin films including conjugated polymer nanoparticles. The nanoparticles with surface bromides can be conjugated with an amine‐functionalized dendrimer via a nucleophilic coupling reaction. Thus, when microliter solutions of the particulates are dragged at a constant velocity on substrates alternately in a layer‐by‐layer manner, thin films composed of the nanoparticles and dendrimers can be successfully built up on the substrates. Our results suggest a methodology to control the deposition of thin films bearing conjugated polymer nanoparticles while minimizing processing time and decreasing material consumption.

     

Sialic Acid Hydroxamate: A Potential Antioxidant and Inhibitor of Metal‐Induced β‐Amyloid Aggregates

Current methods for Alzheimer's treatment require a three‐component system: metal chelators, antioxidants, and amyloid β (Aβ)‐peptide‐binding scaffolds. We report sialic acid (Sia) hydroxamate as a potential radical scavenger and metal chelator to inhibit Aβ aggregation. A cell viability assay revealed that Sia hydroxamate can protect HeLa and glioblastoma (LN229) cells from oxidative damage induced by the Fenton reaction. Sedimentation and turbidity assays showed profound protection of neuroblastoma SH‐SY5Y cells from metal‐induced Aβ aggregation and neural toxicity.     

Exploiting the Lactose–GM3 Interaction for Drug Delivery

Protein–protein and protein–carbohydrate interactions as a means to target the cell surface for therapeutic applications have been extensively investigated. However, carbohydrate–carbohydrate interactions (CCIs) have largely been overlooked. Here, we investigate the concept of CCI‐mediated drug delivery. Lactose‐functionalized β‐cyclodextrin (L‐β‐CD) hosting doxorubicin (Dox) was evaluated for site‐specific delivery to cancer cells via interaction with GM₃, a cell‐surface carbohydrate. The host–guest complex was evaluated in B16 melanoma cells, which express exceptionally high levels of GM₃, and acute monocytic leukemia (THP‐1) and mouse fibroblast (NIH‐3T3) cells, which lack GM₃ on the cell surface. Doxorubicin (Dox) was delivered more efficiently into B16 cells compared with NIH‐3T3 and THP‐1 cells. In B16 cells pretreated with sialidase or sodium periodate, thus preventing CCI formation, drug uptake was significantly decreased. Taken together, the results of these studies strongly support CCI‐mediated uptake via the GM₃–lactose interaction as the mechanism of controlled drug delivery.     

α‐Bis and α,ω‐tetrakis(4‐dimethylaminophenyl) functionalized polymers by atom transfer radical polymerization using 1,1‐bis[(4‐dimethylamino)phenyl]ethylene as tertiary diamine initiator precursor and functionalizing agent

The quantitative syntheses of α‐bis and α,ω‐tetrakis tertiary diamine functionalized polymers by atom transfer radical polymerization (ATRP) methods are described. A tertiary diamine functionalized 1,1‐diphenylethylene derivative, 1,1‐bis[(4‐dimethylamino)phenyl]ethylene (1), was evaluated as a unimolecular tertiary diamine functionalized initiator precursor as well as a functionalizing agent in ATRP reactions. The ATRP of styrene, initiated by a new tertiary diamine functionalized initiator adduct (2), affords the corresponding α‐bis(4‐dimethylaminophenyl) functionalized polystyrene (3). The tertiary diamine functionalized initiator adduct (2) was prepared in situ by the reaction of (1‐bromoethyl)benzene with 1,1‐bis[(4‐dimethylamino)phenyl]ethylene (1) in the presence of a copper (I) bromide/2,2′‐bipyridyl catalyst system. The ATRP of styrene proceeded via a controlled free radical polymerization process to afford quantitative yields of the corresponding α‐bis(4‐dimethylaminophenyl) functionalized polystyrene derivative (3) with predictable number‐average molecular weight (M_n) and narrow molecular weight distribution (M_w/M_n) in a high initiator efficiency reaction. The polymerization process was monitored by gas chromatography analysis. Quantitative yields of α,ω‐tetrakis(4‐dimethylaminophenyl) functionalized polystyrene (4) were obtained by a new post ATRP chain end modification reaction of α‐bis(4‐dimethylaminophenyl) functionalized polystyrene (3) with excess 1,1‐bis[(4‐dimethylamino)phenyl]ethylene (1). The tertiary diamine functionalized initiator precursor 1,1‐bis[(4‐dimethylamino)phenyl]ethylene (1) and the different tertiary amine functionalized polymers were characterized by chromatography, spectroscopy and non‐aqueous titration measurements. Copyright © 2012 Society of Chemical Industry     

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.     

Preparation and characteristic of lactose‐oleoylchitosan and the application of its self‐aggregates as drug delivery system

Amphiphilic polymers lactose‐oleoylchitosan (Lac‐OCH) with different degree of substitution (DS) of lactose were prepared. The chemical structure of the new chitosan derivative was tested and verified. The rheological features including solubility and viscosity of Lac‐OCH were investigated. The introduction of hydrophilic group lactose could improve the solubility of the polymer and Lac‐OCH was soluble in acetic acid solution under pH 7.0. The viscosity of Lac‐OCH decreased a little along with the increasing of DS of lactose. Lac‐OCH with high DS, middle DS, and low DS of lactose possessed small critical aggregation concentration value, and the critical aggregation concentration value rised along with the increasing of DS of lactose. However, the affect was not obvious. In brief, the CAC values were 0.0325, 0.0340, and 0.0344 mg/mL corresponding to the samples of low DS, middle DS, and high DS. Lac‐OCH, obtained by hydrophilic modified using lactose, could also form self‐assembled nanoparticles by oil/water (O/W) emulsification method comparing with OCH. The Lac‐OCH nanoparticles showed dense, axiolitic texture, and the average diameter was approximate 200 nm. The sustained‐release characteristics of Lac‐OCH nanoparticles were studied using Doxorubicin as model drug. The results revealed the promising potential of amphiphilic Lac‐OCH as drug carrier. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011