Burcu Okutucu

Inhibition of alpha-glucosidase by aqueous extracts of some potent antidiabetic medicinal herbs.

Abstract Diabetes mellitus is one of the most prevalant diseases of adults. Agents with α‐glucosidase inhibitory activity have been useful as oral hypoglycemic drugs for the control of hyperglycemia in patients with type 2; noninsulin‐dependent, diabetes mellitus (NIDDM). Investigation of some medicinal herbs: Urtica dioica, Taraxacum officinale, Viscum album, and Myrtus communis with α‐glucosidase inhibitor activity was conducted to identify a prophylactic effect for diabetes in vitro. All plants showed differing potent α‐glucosidase inhibitory activity. However, Myrtus communis strongly inhibited the enzyme (IC50 = 38 µg/mL). The inhibitory effect of these plants and some common antidiabetic drugs against the enzyme source (bakers yeast, rabbit liver, and small intestine) were also searched. Approximately all inhibitors used in this study showed quite different inhibitory activities, according to α‐glucosidase origins. Furthermore, subsequent separation of the active material from Myrtus communis by HPLC showed that only one fraction acted as an α‐glucosidase inhibitor.

Molecularly imprinted polymers for separation of various sugars from human urine.

Molecularly imprinted polymers were the new, simple and unexpensive materials that can be used in several clinical applications. Phenylboronic acid has been frequently used as functional monomer for the covalent imprinting of diols. In this study, the phenylboronic acid esters of fructose, galactose, glucose and raffinose were synthesized and then used as template analytes. The adsorption capacities of fructose, galactose and glucose-phenylboronic acid imprinted polymers were 75, 10 and 30%, respectively. The batch rebinding studies and Scatchard analysis were done for all sugar imprinted polymer. Glucose is one of the mostly found sugar in the urine. The glucose:phenylboronic acid imprinted polymer was used for the analysis of glucose, fructose, galactose, sucrose, maltose, lactose and raffinose in spiked urine. The selectivity of glucose:phenylboronic acid imprinted polymer to urine monosaccharides was found as nearly 45-55% and to di- and polysaccharides was found as 30-35%, respectively.

Noncovalently galactose imprinted polymer for the recognition of different saccharides.

Molecularly imprinted polymers (MIPs) represent a new class of materials possessing high selectivity and affinity for the target molecule. The main goal of this study was to prepare a galactose imprinted polymer and its potential application for the recognition of different saccharides. The selectivity of galactose imprinted polymer for several saccharides; glucose, mannose, fructose, maltose, lactose, sucrose and raffinose was investigated. Macroporous polymer was prepared utilizing ethyleneglycoldimethacrylate as a crosslinking agent, in the presence of galactose as a template molecule with acrylamide as a functional monomer. After the synthesis of polymer, galactose was removed by methanol:acetic acid washing. The selectivity of galactose imprinted polymer for other saccharides was utilized by batch rebinding assay. The arrangement of functional groups within cavities versus shape selectivity is discussed. The results showed that, the orientation of the functional groups was the dominating factor for the selectivity of galactose imprinted polymer. The dissociation constants of polymer were determined by Scatchard analysis.

Optimization of serotonin imprinted polymers and recognition study from platelet rich plasma

Molecularly imprinted polymers using serotonin as the template molecule was prepared for selective recognition from platelet rich plasma by non-covalent imprinting approach. Four different monomers (methacrylic acid, acrylamide, 4-vinylpyridine and 2-acrylamido-2-methylpropane sulfonic acid) and acetonitrile and DMSO as porogen were investigated for the first time by bulk polymerization. The molecularly imprinted polymer which was prepared by acrylamide/methacrylic acid had the largest imprinting factor for serotonin. The affinity and specificity of these polymers were evaluated by equilibrium binding experiments. The effect of polarity of the solvents was examined by polymers binding capacity and imprinting factor. According to the Scatchard analysis the K(d) and Q(max) values were calculated as 1.95 micromoll(-1) and 19.129 micromolg(-1), respectively. The polymer was tested to evaluate serotonin from platelet rich plasma and 70% serotonin recovery was found.

Synthesis and Characterization of AICAR and DOX Conjugated Multifunctional Nanoparticles as a Platform for Synergistic Inhibition of Cancer Cell Growth

The success of cancer treatment depends on the response to chemotherapeutic agents. However, malignancies often acquire resistance to drugs if they are used frequently. Combination therapy involving both a chemotherapeutic agent and molecularly targeted therapy may have the ability to retain and enhance therapeutic efficacy. Here, we addressed this issue by examining the efficacy of a novel therapeutic strategy that combines AICAR and DOX within a multifunctional platform. In this context, we reported the bottom-up synthesis of Fe3O4@SiO2(FITC)-FA/AICAR/DOX multifunctional nanoparticles aiming to neutralize survivin (BIRC5) to potentiate the efficacy of DOX against chemoresistance. The structure of nanoparticles was characterized by dynamic light scattering (DLS), zeta-potential measurement, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and electron microscopy (SEM and STEM with EDX) techniques. Cellular uptake and cytotoxicity experiments demonstrated preferentially targeted delivery of nanoparticles and an efficient reduction of cancer cell viability in five different tumor-derived cell lines (A549, HCT-116, HeLa, Jurkat, and MIA PaCa-2). These results indicate that the multifunctional nanoparticle system possesses high inhibitory drug association and sustained cytotoxic effect with good biocompatibility. This novel approach which combines AICAR and DOX within a single platform might be promising as an antitumor treatment for cancer.

Immobilization of α‐Glucosidase in Chitosan Coated Polygalacturonic Acid

Abstract Crude α‐glucosidase from Bakers yeast was immobilized in polygalacturonic acid beads and coated with chitosan. Chemical and physical characterization were performed by using p‐nitrophenyl‐α‐D‐glucopyranoside (pNPG) as an artificial substrate. Operation, thermal, pH, and strorage stabilities of the free and immobilized enzyme were also examined. The stabilities of immobilized enzyme were found to be better than that of the free enzyme. Furthermore, the hydrolysis rate of the chitosan coated α‐glucosidase polygalacturonic acid beads were studied. In conclusion, the enzyme beads appear to have good characteristics and offer the prospect that this system may find application in enzyme immobilization, in addition to controlled drug release studies.

Covalent attachment of oligonucleotides to cellulose acetate membranes

During the last decade, DNA has become an increasingly important biomolecule in several areas. DNA technology has found many applications, e.g., in forensic science, environmental studies, diagnosis and archeometry. DNA microarrays and DNA biosensors applying the principle of immobilization of oligonucleotide on solid supports are used in these areas. DNA immobilization can be performed by adsorption and covalent attachment. In this study cellulose acetate was used as a solid support for oligonucleotide immobilization. Cellulose acetate was activated with 1,1′-Carbonyldiimidazole (CDI) and then coupled with 1,6-hexanediamine (HDA) as a linker. A hexadecadesoxy oligonucleotide was also activated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and immobilized on the membrane by coupling via amino groups. The effects of various parameters on the immobilization oligonucleotide were investigated.

Therapeutic Effects of AICAR and DOX Conjugated Multifunctional Nanoparticles in Sensitization and Elimination of Cancer Cells via Survivin Targeting

AbstractPurposeResistance to chemotherapy is one of the major problems facing current cancer research. Enhancing tumor cell response to anticancer agents increases chemotherapeutic effectiveness. We have recently addressed this issue and reported on producing multifunctional nanoparticles (Fe3O4@SiO2(FITC)-FA/AICAR/DOX) aiming to overcome chemoresistance with synergetic effect of AICAR and DOX. In the present study, we demonstrated that these nanoparticles not only show enhanced cellular uptake and cytotoxic effect but can also show enhanced pro-apoptotic and anti-proliferative effects in five different tumor-derived cell lines (A549, HCT-116, HeLa, Jurkat and MIA PaCa-2).MethodsThe nanoparticles were examined by using flow cytometric analyses of apoptosis and cell cycle. In addition, we performed caspase-3 activity assay, which supported our flow cytometric data. Furthermore, we demonstrated the applicability of this approach in a variety of cancer types confirming the potential widespread utility of this approach.ResultsWith the concept of co-delivery of AICAR and DOX in the nanoparticle formulation, the use of AICAR against survivin (BIRC5) sensitized cancer cells to DOX chemotherapy which resulted in effective cancer cell elimination. These result showed that combination therapy involving both a molecularly targeted therapy and chemotherapeutic agent has the ability to retain and enhance therapeutic efficacy.ConclusionFe3O4@SiO2(FITC)-FA/AICAR/DOX nanoparticles is superior to monotherapy via the synergetic effect of AICAR and DOX and also the nanoparticle formulation could overcome issues of toxicity with targeted therapy while maintaining the potent anticancer effects of AICAR and DOX. Graphical AbstractApoptosis analysis of A549 cells by flow cytometry-based PE-annexin-V / 7-ADD double staining treated with low-dose (10 μg/ml) concentration of (1) Fe3O4@SiO2(FITC)-FA (2) Fe3O4@SiO2(FITC)-FA/AICAR, (3) Fe3O4@SiO2(FITC)-FA/DOX or (4) Fe3O4@SiO2(FITC)-FA/AICAR/DOX nanoparticles. Viable cells labelled with PE-annexin-V(-)/7-ADD(-), early apoptotic cells labelled with PE-annexin-V(+)/7-ADD(-) and apoptotic cells labelled with PE-annexin-V(+)/ 7-ADD(+) in flow cytometric graphics.

Decolorization of textile wastewater by dye-imprinted polymer

AbstractAdsorption of dye molecules onto a sorbent can be an effective, low-cost method of decolorization of textile wastewater. Most of the techniques used for this aim were the high cost of production and the regeneration also makes them uneconomical. Molecular imprinting polymers are a new kind of materials which can be economical and effective adsorbents. In this study, a molecularly imprinted polymer (MIP) of textile dyes (Direct Red 23) was prepared for decolorization of textile wastewater and also used for leaching of this dye from the wastewater by adsorption of onto polymer. Acrylamide was used as a monomer and dimethyl sulfoxide was used as a porogen. The selective recognition ability of the MIP was studied by an equilibrium-adsorption batch method. The effective adsorption properties of the polymer were tested in synthetic dye wastewater. The high adsorption rate and the amount of imprinted dye that was removed from the polymer was nearly 65%. 80% of the dye was adsorbed by imprinted polymer in...

CONVERSION OF TRYPSIN TO A COPPER ENZYME: TYROSINASE/CATECHOL OXIDASE BY CHEMICAL MODIFICATION

New active sites can be introduced into naturally occurring enzymes by the chemical modification of specific amino acid residues in concert with genetic techniques. Chemical strategies have had a significant impact in the field of enzyme design such as modifying the selectivity and catalytic activity which is very different from those of the corresponding native enzymes. Thus, chemical modification has been exploited for the incorporation of active site binding analogs onto protein templates and for atom replacement in order to generate new functionality such as the conversion of a hydrolase into a peroxidase. The introduction of a coordination complex into a substrate binding pocket of trypsin could probably also be extended to various enzymes of significant therapeutic and biotechnological importance. The aim of this study is the conversion of trypsin into a copper enzyme: tyrosinase by chemical modification. Tyrosinase is a biocatalyst (EC.1.14.18.1) containing two atoms of copper per active site with monooxygenase activity. The active site of trypsin (EC 3.4.21.4), a serine protease was chemically modified by copper (Cu+2) introduced p-aminobenzamidine (pABA- Cu+2: guanidine containing schiff base metal chelate) which exhibits affinity for the carboxylate group in the active site as trypsin-like inhibitor. Trypsin and the resultant semisynthetic enzyme preparation was analysed by means of its trypsin and catechol oxidase/tyrosinase activity. After chemical modification, trypsin-pABA-Cu+2 preparation lost 63% of its trypsin activity and gained tyrosinase/catechol oxidase activity. The kinetic properties (Kcat, Km, Kcat/Km), optimum pH and temperature of the trypsin-pABA-Cu+2 complex was also investigated.