DNA Binding Efficacy Research Articles

In-vitro and in-silico analysis and antitumor studies of novel Cu(II) and V(V) complexes of N-p-Tolylbenzohydroxamic acid

Copper(L2Cu) and vanadium(L2VOCl) complexes of N-p-tolylbenzohydroxamic acid (LH) ligand have been investigated for DNA binding efficacy by multiple analytical, spectral, and computational techniques. The results revealed that complexes as groove binders as evidenced by UV absorption. Fluorescence studies including displacement assay using classical intercalator ethidium bromide as fluorescent probe also confirmed as groove binders. The viscometric analysis too supports the inferences as strong groove binders for both the complexes. Molecular docking too exposed DNA as a target to the complexes which precisely binds L2Cu, in the minor groove region while L2VOCl in major groove region. Molecular dynamic simulation performed on L2Cu complex revealing the interaction of complex with DNA within 20 ns time. The complex stacked into the nitrogen bases of oligonucleotides and the bonding features were intrinsically preserved for longer simulation times. In-vitro cytotoxicity study was undertaken employing MTT assay against the breast cancer cell line (MCF-7). Potential cytotoxic activities were observed for L2Cu and L2VOCl complexes with IC50 values of showing 71 % and 74 % of inhibition respectively.

Synthesis, structure, and in vitro biological studies of benzothiazole based Schiff base ligand and its binary and ternary Co(III) and Ni(II) complexes

Schiff base and its complexes are a renowned class of compounds that are frequently used for clinical investigation to develop less toxic, more potent, and multidrug resistance reversing agents for anticancer activity and other pharmacological actions. Herein, we describe the synthesis of ternary and binary imine base metal complexes derived from benzothiazole heterocyclic core. The Schiff base ligand was prepared by the condensation reaction between of 2,5-dichlorosalicylaldehyde and 2-(2-aminophenyl) benzothiazole. The Schiff base, 2-((E)-(2-(benzo[d]thiazol-2-yl)phenylimino)methyl)-3,5-dichlorophenol, thus obtained was utilized for the preparation of Co(III) and Ni(II) complexes. In addition, 1,10 phenanthroline was used as a co-ligand in the formation of mixed ligand complexes with Co(III) and Ni(II) metal ions. The physico-chemical characterization of the above prepared ligand and coordination complexes was performed using methods viz., elemental analysis, electronic absorption, mass and NMR spectral studies and thermal analysis. Furthermore, the crystalline nature of the compounds was studied using powder-XRD patterns, which revealed that the mixed ligand complexes have a more amorphous nature with slight semicrystalline portions. All the synthesized coordination complexes agree with the expected octahedral geometry. The biological potency of the ligand and its complexes were evaluated for their antioxidant properties using DPPH assay, antibacterial studies against two gram-positive (Staphylococcus aureus, and Bacillus subtilis), and two gram-negative bacterial strains (Escherichia coli, andPseudomonas aeruginosa). The complexes were also investigated for their DNA binding efficacy, DNA incision properties, and in vitro cytotoxicity using the MTT assay. The current study indicates that the mixed complexes exhibit increased pharmacological behaviour compared to their ternary complexes and organic counterparts.

Sumoylation of Cas9 at lysine 848 regulates protein stability and DNA binding.

CRISPR/Cas9 is a popular genome editing technology. Although widely used, little is known about how this prokaryotic system behaves in humans. An unwanted consequence of eukaryotic Cas9 expression is off-target DNA binding leading to mutagenesis. Safer clinical implementation of CRISPR/Cas9 necessitates a finer understanding of the regulatory mechanisms governing Cas9 behavior in humans. Here, we report our discovery of Cas9 sumoylation and ubiquitylation, the first post-translational modifications to be described on this enzyme. We found that the major SUMO2/3 conjugation site on Cas9 is K848, a key positively charged residue in the HNH nuclease domain that is known to interact with target DNA and contribute to off-target DNA binding. Our results suggest that Cas9 ubiquitylation leads to decreased stability via proteasomal degradation. Preventing Cas9 sumoylation through conversion of K848 into arginine or pharmacologic inhibition of cellular sumoylation enhances the enzyme's turnover and diminishes guide RNA-directed DNA binding efficacy, suggesting that sumoylation at this site regulates Cas9 stability and DNA binding. More research is needed to fully understand the implications of these modifications for Cas9 specificity.

Synthesis, structure, DNA/protein molecular docking and biological studies of hydrazone ligand derived Cu(II) and VO(IV) complexes

In this study, Cu(II) (1) and VO(IV) (2) complexes are synthesized from hydrazones, HL1=(E)-N′-(2-hydroxy-3,5-diiodobenzylidene)-4-tert-butylbenzohydrazide and HL2=(E)-N′-(3-bromo-5-chloro-2-hydroxybenzylidene)-4-tert-butylbenzohydrazide and are well characterized by the way of different spectroscopic and analytical techniques. The chemical structure of complexes 1 and 2 is confirmed by single crystal X-ray crystallography studies. The molecular docking studies are carried out to better comprehend the preferential mode of binding of these compounds against biomecular targets such as DNA and plasma protein (HSA). Complex 1 revealed the lowest ACE value (−503.36 kcal/mol), suggests that the potential DNA binding efficacy of complex 1 is being stronger than the other compounds of interest. Besides, complexes 1 and 2 displayed better binding affinities with HSA protein molecules relative to their respective parent hydrozone ligands. These results have been reflected as their significant antibacterial and antifungal activities.

Etched Fiber Bragg Grating Sensor for Quantification of DNA

The detection and quantification of DNA is of critical importance in various molecular biology processes and has applications in fields ranging from forensics to environmental monitoring. Here, the development of a highly sensitive and label-free technique for DNA detection is reported. This article proposes a reduced graphene oxide (rGO) coated etched Fiber Bragg Grating (eFBG) sensor as a tool for the detection and quantification of dsDNA. The proposed sensor is found to have a limit of detection of 261.87 pg/$\mu \text{l}$ and the sensor response is a linear function of the dsDNA concentration in the range between 1 ng/$\mu \text{l}$ to 50 ng/$\mu \text{l}$ with excellent stability and repeatability. The paper also proposes a technique to quantitatively measure the amount of DNA bound to the sensor and thus, the DNA binding efficacy of the rGO coating on the sensor, utilizing UV spectrometry.

Cationic Block Copolymer Nanoparticles with Tunable DNA Affinity for Treating Rheumatoid Arthritis

AbstractA high concentration of cell‐free DNA (cfDNA) in joints is considered a disease causative agent of rheumatoid arthritis (RA) and cfDNA scavenging has been regarded as an efficient therapeutic avenue. Cationic polymers can hamper progression of joint inflammation in a rat model of RA by scavenging cfDNA; however, they may cause systemic toxicity due to the strong positive charges. To reduce the toxicity, herein a library of cationic nanoparticles (cNPs) of block copolymer micelles is developed and the effects of structure and surface composition on cNP efficacy to bind nucleic acids, toxicity, and therapeutic activity on a collagen induced arthritis (CIA) rat model of RA are assessed. The library includes cNPs with a homoshell from poly(lactic‐co‐glycolic acid)‐block‐poly(2‐(dimethylamino)ethyl methacrylate) (PLGA‐b‐PDMA) block copolymers and cNPs with a mixed shell of poly(ethylene glycol) (PEG) and PDMA by coself‐assembling PLGA‐b‐PDMA and PLGA‐b‐PEG block copolymers. Relatively to the homoshell cNPs, introduction of PEG segments translates into a lower DNA binding efficacy while preserving ability to hamper joint inflammation. Moreover, they show a greater accumulation and longer retention at the inflamed joints, allowing a lower administration frequency. In conclusion, this work shows that the therapeutic index of cationic materials can be tuned by introducing surface neutral moieties.

DNA binding efficacy with functionalized folic acid-PAMAM nanoparticles

Functionalized folic-polymers were often used for gene and drug delivery. DNA binding to folic acid-PAMAM conjugates was studied, using multiple spectroscopic methods, thermodynamic analysis and transmission electron microscopy (TEM). Thermodynamic parameters showed DNA-folic acid-PAMAM conjugation occurs via H-bonding, hydrophobic and van der Waals contacts. As nanoparticle size increases the loading efficacy and the stability of DNA conjugates are enhanced. TEM analysis showed major DNA morphological changes, upon folic acid-PAMAM conjugation. Folic acid-PAMAM nanoparticles can transport DNA in vitro.

Synthesis of a Naturally Occurring Plant Alkaloid Berberine Analogue and Its Application in Nanomolar Selective Detection of Hydrazine in Free and DNA‐Binding Situation.

AbstractA sensitive platform for in vivo selective detection of the toxic element by a DNA stabilized biomolecule is of great importance. Particularly sensing of hydrazine in the presence of DNA is very important during cell damage and post‐mortem. In this study, a new 9‐O‐(4‐nitrobenzoyl) berberine analogue was designed and synthesized. The Calf thymus DNA (CT‐DNA) binding affinity studies revealed that the analogue was excellent DNA binding efficacy with groove binding mode (K= 4.2 × 106 M−1) compared to parent berberine (K= 2.2 ×105 M−1). Importantly, our synthesized analogue for the first time a berberine analogue that can effectively use as a selective ratiometric colorimetric probe for hydrazine detection based on ICT (intramolecular charge transfer) mechanism with a good limit of detection (20nM) which is much below the threshold limiting value (TLV) of hydrazine (10 ppb or 312 nM) as regulated by Environmental protection agency (EPA). Interestingly, we report a new avenue in sensing study in the presence of DNA i. e. our DNA groove binding analogue (at maximum saturation) also can serve as a promising turn on fluorimetric sensor for hydrazine detection with high selectivity over biologically abundant amines and metal cations with well limit of detection (LOD) value (14 nM). The sensing mechanism in the absence of DNA and in the presence of DNA was established by different spectroscopic methods. In addition, the berberine analogue could also be utilized for qualitative detection of hydrazine in the vapor phase and for the imaging of hydrazine in living Michigan Cancer Foundation‐7 (MCF‐7) cells.

An investigation on the DNA/protein binding, DNA cleavage and in vitro anticancer properties of SNO pincer type palladium(II) complexes with N-substituted isatin thiosemicarbazone ligands

Three pincer type palladium(II) complexes (1–3) were synthesised from the reactions of PdCl2 with thiosemicarbazone ligands (L1–L3), and characterized by elemental analyses and UV Visible, FT-IR, 1H &13C NMR spectroscopic techniques. The molecular structure of 2 was confirmed by single crystal X-ray crystallography. The X-ray diffraction study of complex 2 revealed the pincer type tridentate SNO coordination of N-substituted isatin thiosemicarnbazone with the palladium ion. The binding affinity and mode of the palladium(II) complexes (1–3) toward calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) were determined by UV–Visible and fluorescence spectrophotometric methods. Spectral evidences showed intercalative mode of DNA binding with the palladium(II) complexes. The magnitude of hypochromism is in the order of 3>2>1, which reflects the DNA binding efficacy of the complexes. The binding mode was further confirmed by CD spectra which indicate the non-groove mode of binding; hence the intercalative mode of binding is proposed. The alterations in the secondary structure of the protein by the complexes were confirmed by synchronous fluorescence spectroscopic studies. Spectral evidences also showed good binding property of the complexes with the protein. Complexes (1–3) cleaved the pUC19 plasmid DNA in the absence of an external agent. The complexes were found to possess significant in vitro cytotoxicity against human breast (MCF7) and lung (A549) cancer cell lines.

Small hydrophobe substitution on polyethyleneimine for effective plasmid DNA delivery

Event Abstract Back to Event Small hydrophobe substitution on polyethyleneimine for effective plasmid DNA delivery Bindu Thapa1, Samarwadee Plianwong2, Remant Kc3, Bradely Rutherford3 and Hasan Uludag1, 3, 4 1 University of Alberta, Faculty of Pharmacy and Pharmaceutical Sciences, Canada 2 Silpakorn University, Faculty of Pharmacy, Thailand 3 University of Alberta, Department of Chemical and Material Engineering, Canada 4 University of Alberta, Department of Biomedical Engineering, Canada Introduction: Improved delivery systems are needed for intracellular delivery of sensitive biologics such as plasmid DNA. Cationic polymers have been developed for this end due to their safety and facile chemistry to tailor their properties. These polymers complex with DNA via electrostatic interactions, and condense them into compact nano-sized polyplexes. Chemical modification of low molecular weight PEIs with hydrophobic groups improves delivery due enhanced cellular uptake and unpacking efficacy of the polyplexes. Unlike bulky lipids, the impact of small hydrophobes on cationic polymers for DNA delivery has not been explored in detail; it is possible that small hydrophobes might be superior substituents due to better grafting reactions and unique properties. In this study, we modified 1.2 kDa PEIs using small hydrophobe propionate (PrA; CH2-CH3) and extensively explored the features of resultant DNA polyplexes and delivery efficiency. Materials and Methods: The PrA grafted 1.2 PEI (PEI-PrA; Figure 1) was synthesized via N-acylation and characterized through 1H-NMR spectroscopy[1]. DNA binding efficacy of PEI1.2-PrAs were investigated through agarose gel electrophoresis and size-surface charge through dynamic light scattering[2]. Cellular toxicity, DNA uptake (with Cy3-labeleld DNA) and transfection efficacy of PEI1.2-PrA/DNA complexes was studied in breast cancer cells MDA-231 and MCF-7 as a function of PrA substitution amount, post transfection time and polymer:DNA ratio for complex formation. Green fluorescent protein (GFP) transfection was assessed by flow cytometry. Results and Discussions: Substitution efficacy of PrA onto 1.2 PEI was increased with feed ratio (PrA/PEI) with highest grafting of 1.6 PrA/PEI. DNA binding efficacy of PEI-PrA was decreased in proportion with PrA substitution as a consequences of –NH2 consumption and/or steric hindrances. Hydrodynamic size of polyplexes was identical irrespective to PrA substitution, but surface charge initially increased with PrA substitution and later decreased at high PrA substitutions. Cellular toxicity of the polymers was increased with PrA substitution but the polymers still displayed less toxicity compared to 25 kDa PEI (PEI25). GFP transfection efficiency in both MDA-231 and MCF-7 was significantly increased with optimal PrA substitution (0.5-1 PrA/PEI) while polymers with the highest substitution and parent polymer were ineffective (Figure 2). These results paralleled the results obtained from cellular uptake of plasmid DNA. Importantly, transfection efficiency of PEI-PrA1 (PrA/PEI = 0.76) was higher than long chain lipid (C=18) grafted 1.2 PEI and comparable to PEI25. In addition, PEI-PrA1 showed higher transfection than PEI 25 at day 7 and 14, showing a relatively stable transfection in MDA-231 cells. Conclusions: Substitution of small hydrophobe PrA onto PEI1.2 enhanced transfection efficiency in breast cancer cells, but excess substitution (>1.2 PrA/PEI) was detrimental, emphasizing the importance of balancing polymer hydrophobicity for effective gene delivery. Thus, integration of small hydrophobe onto low molecular weight PEIs seems as effective as large lipids. This study was supported by an NCPRM (NSERC CREATE program for regenerative medicine)

New 13-pyridinealkyl berberine analogues intercalate to DNA and induce apoptosis in HepG2 and MCF-7 cells through ROS mediated p53 dependent pathway: biophysical, biochemical and molecular modeling studies

A new series of 13-pyridinealkyl berberine analogues was synthesized and their DNA binding efficacy studied by employing spectroscopic, calorimetric and molecular modeling techniques.

Genomic Heat Shock Element Sequences Drive Cooperative Human Heat Shock Factor 1 DNA Binding and Selectivity

The heat shock transcription factor 1 (HSF1) activates expression of a variety of genes involved in cell survival, including protein chaperones, the protein degradation machinery, anti-apoptotic proteins, and transcription factors. Although HSF1 activation has been linked to amelioration of neurodegenerative disease, cancer cells exhibit a dependence on HSF1 for survival. Indeed, HSF1 drives a program of gene expression in cancer cells that is distinct from that activated in response to proteotoxic stress, and HSF1 DNA binding activity is elevated in cycling cells as compared with arrested cells. Active HSF1 homotrimerizes and binds to a DNA sequence consisting of inverted repeats of the pentameric sequence nGAAn, known as heat shock elements (HSEs). Recent comprehensive ChIP-seq experiments demonstrated that the architecture of HSEs is very diverse in the human genome, with deviations from the consensus sequence in the spacing, orientation, and extent of HSE repeats that could influence HSF1 DNA binding efficacy and the kinetics and magnitude of target gene expression. To understand the mechanisms that dictate binding specificity, HSF1 was purified as either a monomer or trimer and used to evaluate DNA-binding site preferences in vitro using fluorescence polarization and thermal denaturation profiling. These results were compared with quantitative chromatin immunoprecipitation assays in vivo. We demonstrate a role for specific orientations of extended HSE sequences in driving preferential HSF1 DNA binding to target loci in vivo. These studies provide a biochemical basis for understanding differential HSF1 target gene recognition and transcription in neurodegenerative disease and in cancer.

Quercetin counteracts the cellular damage caused by HNE and inhibits inflammation in ARPE‐19 cells

AbstractPurpose Age‐related macular degeneration(AMD) is the leading cause of blindness in the western world. And despite extensive research many questions about disease progression and formation still remain unanswered. One of the driving factors of AMD is a chronic inflammatory process, stimulated by life‐long exposure to light and oxidative stress. In the current study we try to evaluate the anti‐inflammatory properties of Quercetin, a plant derived polyphenol, and to determine the pathways by which it inhibits inflammation.Methods Cultured ARPE‐19 cells were treated with the lipid peroxidation endproduct 4‐Hydroxynonenal (HNE) to induce an inflammatory response. Quercetin was added 1 hour after stimulation with HNE to assess its power to suppress an already activated inflammatory response. The effects of the treatment on intracellular inflammation were measured with ELISA and quantitative Real‐Time PCR. Cell viability was assessed using the lactate dehydrogenase (LDH)‐assay.Results Our results show that Quercetin decreased the levels of the pro‐inflammatory cytokines MCP‐1 and IL‐8. It also protected the cells from HNE‐induced toxicity, as was evidenced by a decrease in LDH levels. Quercetin lowered the levels of mitogen‐activated protein kinase (MAP) p38 and of phospho‐CREB but did not affect the levels of NF‐κB or the DNA binding efficacy of its subunit p65.Conclusion Our results show that Quercetin can reduce the inflammatory response in retinal pigment epithelial cells by down regulating the MAPK pathway and decreasing the phosphorylation of CREB. Furthermore it is able to protect cells from death induced by oxidative stress. Quercetin may, therefore, be a valuable tool in the therapy of inflammation in AMD.

Structure–activity relationship of human liver-expressed antimicrobial peptide 2

Liver-expressed antimicrobial peptide 2 (LEAP-2) is a 40-residue cationic peptide originally purified from human blood ultrafiltrate. The native peptide contains two disulfide bonds and is unique regarding its primary structure. Its biological role is not known but a previous study showed that chemically synthesized LEAP-2 exhibited in vitro antimicrobial activities against several Gram-positive bacteria. In order to determine its antimicrobial mode of action, we expressed human recombinant LEAP-2 in Escherichia coli. Circular dichroism spectroscopy and nuclear magnetic resonance analyses showed that the structure of the recombinant peptide was identical to that of the chemically synthesized and oxidized LEAP-2, with two disulfide bonds between Cys residues in relative 1–3 and 2–4 positions. Minimal inhibitory concentration (MIC) of the recombinant human LEAP-2 was determined by a conventional broth dilution assay. It was found to be bactericidal against Bacillus megaterium at a 200μM concentration. Interestingly, the linear LEAP-2 had a greater antimicrobial activity with a MIC value of 12.5μM, which was comparable to that of magainin2. SYTOX Green uptake was used to assess bacterial membrane integrity. Linear LEAP-2 and magainin2 permeabilized B. megaterium membranes with the same efficiency, whereas oxidized LEAP-2 did not induce stain uptake. Binding of the peptides to plasmid DNA was evaluated by gel retardation assays. The DNA-binding efficacy of linear LEAP-2 was three times higher than that of the peptide-containing disulfide bridges. Altogether, these results show that the secondary structure of human LEAP-2 has a profound impact on its antibacterial activity.

DNA cleavage, binding and intercalation studies of drug-based oxovanadium(IV) complexes

The complexes of oxovanadium(IV) with ciprofloxacin and various uni-negative bidentate ligands have been prepared and their structure investigated using spectral, physicochemical and elemental analyses. The viscosity measurement suggest that the complexes bind to DNA by intercalation. The DNA binding efficacy was determined using absorption titration to obtain the binding constant (Kb). The DNA cleavage efficacy was determined using gel electrophoresis. The DNA binding and cleavage efficacy were increased in the complexes relative to the parental ligands and metal salts. Antibacterial activity has been assayed against two Gram( − ve) i.e. Escherichia coli, Pseudomonas aeruginosa and three Gram( + ve) Staphylococcus aureus, Bacillus subtilis, Serratia marcescens microorganisms using the doubling dilution technique. The results show a significant increase in antibacterial activity in the complexes compared with parental ligands and metal salts.

Substituent control of DNA binding modes in a series of chalcogenoxanthylium photosensitizers as determined by isothermal titration calorimetry and topoisomerase I DNA unwinding assay

The DNA binding efficacy and preferred mode of binding of a series of rhodamine-related chalcogenoxanthylium dyes was investigated by isothermal titration calorimetry (ITC) using ctDNA, [poly(dCdG)] 2 and [poly(dAdT)] 2, and by a topoisomerase I DNA unwinding (Topo I) assay. The dyes of this study showed tight binding to ctDNA with binding constants, K b, on the order of 10 6–10 7 M −1. The ITC and Topo I assay studies suggested that the 9-substituent has a strong impact on binding modes ranging from an apparent preference for intercalation with a 9-2-thienyl substituent (similar binding to [poly(dCdG)] 2 and [poly(dAdT)] 2, re-supercoiling of DNA in the Topo I assay at <10 −5 M dye), to mixed binding modes with 9-phenyl derivatives (2- to 3-fold preference for binding to [poly(dAdT)] 2, re-supercoiling of DNA in the Topo I assay at ∼2 × 10 −5 M dye), to minor groove binding in a 9-(2-thienyl-5-diethylcarboxamide) derivative (strong preference for binding to [poly(dAdT)] 2, did not show complete re-supercoiling in the Topo I assay). No binding to ctDNA was observed in one derivative with a 9-(3-thienyl-2-diethylcarboxamide) substituent, which cannot be co-planar with the xanthylium core. In series of dyes where the chalcogen atom was varied, the selenoxanthylium derivatives had 2- to 3-fold higher values of K b than the corresponding xanthylium, thioxanthylium, or telluroxanthylium derivatives, which all showed comparable values of K b. The chalcogen atom appeared to have little influence on binding mode.

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In this study, Cu(II) (1) and VO(IV) (2) complexes are synthesized from hydrazones, HL1=(E)-N′-(2-hydroxy-3,5-diiodobenzylidene)-4-tert-butylbenzohydrazide and HL2=(E)-N′-(3-bromo-5-chloro-2-hydroxybenzylidene)-4-tert-butylbenzohydrazide and are well characterized by the way of different spectroscopic and analytical techniques. The chemical structure of complexes 1 and 2 is confirmed by single crystal X-ray crystallography studies. The molecular docking studies are carried out to better comprehend the preferential mode of binding of these compounds against biomecular targets such as DNA and plasma protein (HSA). Complex 1 revealed the lowest ACE value (−503.36 kcal/mol), suggests that the potential DNA binding efficacy of complex 1 is being stronger than the other compounds of interest. Besides, complexes 1 and 2 displayed better binding affinities with HSA protein molecules relative to their respective parent hydrozone ligands. These results have been reflected as their significant antibacterial and antifungal activities.

Investigation of DNA-Binding Properties of an Aminoglycoside-Polyamine Library Using Quantitative Structure−Activity Relationship (QSAR) Models

We have recently developed a novel multivalent cationic library based on the derivatization of aminoglycosides by linear polyamines. In the current study, we describe the DNA-binding activity of this library. Screening results indicated that several candidates from the library showed high DNA-binding activities with some approaching those of cationic polymers. Quantitative Structure-Activity Relationship (QSAR) models of the screening data were employed to investigate the physicochemical effects governing polyamine-DNA binding. The utility of these models for the a priori prediction of polyamine-DNA-binding affinity was also demonstrated. Molecular descriptors selected in the QSAR modeling indicated that molecular size, basicity, methylene group spacing between amine centers, and hydrogen-bond donor groups of the polyamine ligands were important contributors to their DNA-binding efficacy. The research described in this paper has led to the development of new multivalent ligands with high DNA-binding activity and improved our understanding of structure-activity relationships involved in polyamine-DNA binding. These results have implications for the discovery of novel polyamine ligands for nonviral gene delivery, plasmid DNA purification, and anticancer therapeutics.

Antitumor-Active Cobalt−Alkyne Complexes Derived from Acetylsalicylic Acid: Studies on the Mode of Drug Action

Cobalt-alkyne complexes are drugs with remarkable cytotoxicity. From the complexes tested up to now we selected the aspirin derivative [2-acetoxy-(2-propynyl)benzoate]hexacarbonyldicobalt (Co-ASS) as the lead compound. To get more insight into the mode of action, we systematically modified the alkyne ligand and determined the cytotoxic properties of the resulting cobalt complexes. Further investigations were performed on the drug lipophilicity, the cellular uptake into MCF-7 and MDA-MB 231 breast cancer cells, the DNA-binding efficacy, and the nuclear drug content. The ability to inhibit glutathione reductase and cyclooxygenase (COX) enzymes, the binding to the estrogen receptor, and the induction of apoptotic processes were examined for selected compounds. Interestingly, the most antitumor active compounds were potent COX inhibitors (COX-1 and COX-2). The presented results indicate that cobalt-alkyne complexes of the Co-ASS type, represent a new class of organometallic cytostatics with a mode of drug action in which COX inhibition probably plays a major role.

Chemoenzymatic synthesis and high-throughput screening of an aminoglycoside-polyamine library: identification of high-affinity displacers and DNA-binding ligands.

Chemoenzymatic parallel synthesis and high-throughput screening were employed to develop a multivalent aminoglycoside-polyamine library for use as high-affinity cation-exchange displacers and DNA-binding ligands. Regioselective lipase-catalyzed acylation, followed by chemical aminolysis, was used to generate vinyl carbonate and vinyl carbamate linkers, respectively, of the aminoglycosidic cores. These were further derivatized with polyamines, leading to library generation. A parallel batch-displacement assay was employed to identify the efficacy of the library candidates as potential displacers for protein purification. Using this approach, low-molecular-mass displacers with affinities higher than those previously observed have been identified. The aminoglycoside-polyamine library was also screened for DNA binding efficacy using an ethidium bromide displacement assay. These highly cationic molecules exhibited strong DNA-binding properties and may have potential for enhanced gene delivery.