Inclusion complexes of N-sulfamoyloxazolidinones with beta-cyclodextrin

A study of inclusion complexes of six N-sulfamoyloxazolidinone derivatives with beta-cyclodextrin is described. The inclusion complexes were prepared in solution and in solid state with stoichiometry host-guest 1:1, and characterized. In solution, the complexation was carried out by spectrophotometric measurements at 25 degrees C. The stoichiometries and stability constants of complexes at various pHs have been determined using second-derivative spectrophotometry UV-vis. Hydrophobic properties of N-sulfamoyloxazolidinones are improved following their inclusion into beta-CD.     

Inclusion complexes of ketosteroids with beta-cyclodextrin

Inclusion complexes of several steroid derivatives with beta-cyclodextrin (7) were studied in dimethylsulfoxide solution. The investigated molecules were ketosteroids with different functional groups on the skeleton: 3beta-acetoxypregn-5-en-20-one (1), 3beta-acetoxypregna-5,16-dien-20-one (2), 3beta-acetoxyandrost-5-en-17-one (3), 3beta-hydroxyandrost-5-en-17-one (4), 5alpha-androstane-3,17-dione (5) and 17beta-hydroxyandrost-4-en-3-one (6). Complex formation was monitored by two-dimensional ROESY experiments through the detection of intermolecular dipolar interactions. In case of inclusion complex formation, the steroid molecule penetrates the cavity of the cyclodextrin and dipole-dipole interactions (ROEs) can be detected between the glucose H-3 and H-5 protons inside the cyclodextrin cavity and the steroid skeletal protons. Intermolecular interactions were detected in all six cases. However, ROESY experiments provided data indicating only partial immersion (A and B ring of the steroid skeleton) in case of 1, 2 and 6. On the contrary, compounds 3 and 5, showing the most correlation rich spectra, seem to fully immerse in the beta-cyclodextrin cavity.     

Inclusion complex of fenbufen with beta-cyclodextrin

An inclusion complex of fenbufen with beta-cyclodextrin (beta-CD) in aqueous solution was characterized by (1)H-NMR spectroscopy. The [1:1] stoichiometry was determined and a stability constant of several 1000s (M(-1)) was calculated. The geometry of the inclusion complex was established based on MM(+) molecular mechanics calculations.     

Molecularly imprinted polymer microspheres for solid-phase extraction of chloramphenicol residues in foods

Preparation of molecularly imprinted polymer microspheres (MIPMs) for chloramphenicol (CAP) by aqueous suspension polymerization is reported for the first time in this study. The resulting MIPMs had the ability to specifically adsorb CAP, and the molecularly imprinted solid phase extraction (MISPE) based on the MIPMs was shown to be applicable for clean-up and preconcentration of trace CAP in milk and shrimp samples with high recoveries of 92.7% and 84.9%, respectively. Combined with MISPE, the conventional HPLC-UV analysis sensitivity for CAP in foods could be significantly increased.     

A new molecularly imprinted polymer for the selective extraction of naproxen from urine samples by solid-phase extraction

A non-covalent molecularly imprinted polymer (MIP) was synthesised using naproxen (a non-steroidal, anti-inflammatory drug (NSAID)) as a template molecule. The MIP was chromatographically evaluated to confirm the imprinting effect, and was then applied as a selective sorbent in solid-phase extraction (SPE) to selectively extract naproxen. After this study, the MIP was used to extract naproxen from urine samples; it was demonstrated that by applying a selective washing step with acetonitrile (ACN) the compounds in the sample that were structurally related to naproxen could be eliminated.     

Degradation of phenol by polymer entrapped microorganisms

Summary A Pseudomonas sp. which was isolated from phenol-containing soil was immobilized in alginate and polyacrylamide-hydrazide (PAAH) and cultivated in a special airlift fermenter.The immobilized Pseudomonas sp. was able to degrade phenol at initial concentrations up to 2 g/l in less than 2 days, although the free cells did not grow at this concentration.The immobilization materials act as a protective cover against phenol, PAAH being more effective than alginate. The degradation activity as well as the outgrowth of bacteria can be manipulated by the concentration of the immobilization material, the temperature and the nitrogen content in the medium.The cells grew predominantly in microcolonies in the outer area of the beads when nitrogen was available as 1.0g NH₄NO₃/l and 0.5g (NH₄)₂SO₄/l.Prof. Dr. A. Fiechter dedicated to his 60th birthday     

Studies on adsorption of dyes on beta-cyclodextrin polymer

Beta-cyclodextrin (beta-CD) polymers are used for the removal of various dyes from aqueous solutions. Three insoluble polymers with different degrees of beta-CD were used. Results of adsorption experiments showed that these polymers exhibited high sorption capacities toward dyes. The mechanism of adsorption was both physical adsorption and hydrogen bonding due to the polymer and the formation of an inclusion complex due to the beta-CD molecules through host-guest interactions.     

Inclusion complexes of bisphenol A with cyclomaltoheptaose (beta-cyclodextrin): solubilization and structure

The inclusion complexation behavior and the solubilization effects of Bisphenol A (BPA, an endocrine-disrupting chemical) by cyclomaltohexaose, -heptaose, and -octaose (alpha-, beta-, and gamma-cyclodextrins) were investigated by (1)H NMR spectroscopy and by elemental analysis. The results showed that beta- and gamma-cyclodextrins gave the satisfactory solubilization ability to BPA up to 7.2x10(3)mgL(-1) and 9.0x10(3)mgL(-1), respectively. X-ray crystallographic diffraction and ROESY spectroscopy were also employed to investigate the structure of the beta-CD/BPA inclusion complex in both aqueous solution and the solid state. The result showed that this complex adopted a 2:2 stoichiometry in the solid state, that is, a head-to-head beta-CD dimer accommodated two BPA molecules. The inclusion of BPA led to the desolvation of the beta-CD cavity and the destruction of the circularly closed hydrogen-bond network in the secondary side of beta-CD, which made the complex more soluble.     

Storage of industrial microorganisms entrapped into polymer matrices

Our study of the techniques of long-term storage of the biomass of various strains of microorganisms, which cause breakdown or transformation of synthetic organic compounds, demonstrates that desiccated agar beads with immobilized microbial cells can be used for this purpose. In addition, the cells can be stored in desiccated matrices of agar or polyvinyl alcohol, coating synthetic cords. Such dry biocatalysts may be used for quick starting of bioreactors and in other biotechnological processes. The technique is applicable to storage of various strains of Pseudomonas, Corynebacterium, Rhodococcus, and, to a lesser extent, Enterobacteriaceae.     

Molecularly imprinted polymer of 5-methyluridine for solid-phase extraction of pyrimidine nucleoside cancer markers in urine

Normal and modified urinary nucleosides represent potential biomarkers for cancer diagnosis. To selectively extract modified nucleosides, we developed a molecularly imprinted polymer (MIP) of 5-methyluridine as selective material for molecularly imprinted solid-phase extraction (MISPE). The MIPs were obtained from vinyl-phenylboronate ester derivative of the template, acrylamide and pentaerythritol triacrylate co-polymer, and were tested in batch and cartridge experiments with aqueous samples. Our results indicated that the imprinted polymer was selective for pyrimidine nucleosides with a K(d) and a B(max) of 46 microM and 18 micromol/g, respectively. Finally, a MISPE of the most common pyrimidine nucleoside cancer markers in urine sample was realized.     

Determination of tobramycin in soil by HPLC with ultrasonic-assisted extraction and solid-phase extraction

Pharmaceuticals residues in the environment have become a growing scientific interest worldwide. In the light of the possible harmful effects of tobramycin, a rapid and sensitive analytical method for determination of tobramycin in soil was developed. The extraction and purification methods, derivatization conditions, and chromatographic conditions in the determination of tobramycin in soil have been fully investigated. Extraction was carried out by a combination of vortex mixer and ultrasonic oscillation using acetone/water as the extraction agent. The extract was concentrated to 1 mL and passed through the C(18) SPE cartridge rinsed with water (3 mL), methanol (3 mL). The derivatization procedure was followed by the reaction of tobramycin with 4-Chloro-3,5-dinitrobenzotrifluoride at 60°C for 10 min in pH 9.0 H(3)BO(3)-Na(2)B(4)O(7) medium. The labeled tobramycin was determined by high performance liquid chromatography at 245 nm. Separation was accomplished within 15 min in gradient elution mode with trifluoroacetic acid in mobile phase as ion-pair reagent. The correlation coefficient for the method was 0.9999 in concentrations ranging from 0.10 to 100.0 μg/g. The limit of detection was 0.02 μg/g for tobramycin in soil at a signal-to-noise ratio of 3. The calculated recoveries of the proposed method were from 78.0 to 91.0% and RSDs were 3.38-9.79% in the application to the quantitative determination of tobramycin in all types of soil. The method will help to establish adequate monitoring of tobramycin residue in soil and make the contribution to environmental behavior evaluation.     

Selective solid-phase extraction using molecularly imprinted polymer for analysis of methamidophos in water and soil samples

An analytical methodology for the analysis of methamidophos in water and soil samples incorporating a molecularly imprinted solid-phase extraction process using methamidophos-imprinted polymer was developed. Binding study demonstrated that the polymer exhibited excellent affinity and high selectivity to the methamidophos. Evidence was also found by FT-IR analysis that hydrogen bonding between the CO(2)H in the polymer cavities and the NH(2) and P=O of the template was the origin of methamidophos recognition. The use of molecularly imprinted solid-phase extraction improved the accuracy and precision of the GC method and lowered the limit of detection. The recovery of methamidophos extracted from a 10.0 g soil sample at the 100 ng/g spike level was 95.4%. The limit of detection was 3.8 ng/g. The recovery of methamidophos extracted from 100 mL tap and river water at 1 ng/mL spike level was 96.1% and 95.8%, and the limits of detection were 10 and 13 ng/L respectively. These molecularly imprinted solid-phase extraction procedures enabled selective extraction of polar methamidophos successfully from water and soil samples, demonstrating the potential of molecularly imprinted solid-phase extraction for rapid, selective, and cost-effective sample pretreatment.     

Group-selective molecularly imprinted polymer solid-phase extraction for the simultaneous determination of six sulfonamides in aquaculture products

Group-selective molecularly imprinted polymers (MIPs) made from sulfonamides (SAs) using functional monomer methacrylic acid (MAA) were synthesized. The derived molecularly imprinted solid-phase extraction (MISPE) cartridges were developed for the purification and enrichment of aquatic products. The optimum template molecule and the ratio of the functional monomer to the template for obtaining group selectivity to SAs were sulfadimethoxine (SDM) and 4:1, respectively. The MIPs were characterized by Brunauer-Emmett-Teller (BET), scatchard plot, and chromatography analysis, all of which demonstrate better chromatographic behavior and group-selectivity of MIPs for SAs compared with those of corresponding NIPs. The extraction conditions of MISPE for six SAs were optimized; the method precision and accuracy were satisfactory for the fish and shrimp samples at 0.05, 0.1, and 0.2 mg kg(-1) spiked levels. Recoveries ranging from 85.5% to 106.1% (RSD, 1.2-7.0%, n=3) were achieved. The limits of detection (S/N=3) and quantitation (S/N=10) in the shrimp and fish samples were achieved from 8.4 to 10.9 μg kg(-1) and from 22.4 to 27.7 μg kg(-1), respectively. Therefore, the obtained MIPs and MISPE can be employed for the enrichment and clean-up of SAs. This paper presents a new analytical method which enables the simultaneous determination and quantification of SAs in aquaculture products.     

Biological transformations of steroidal compounds: A review

Microbial transformation is an important tool for structural modification of organic compounds, especially natural products with complex structures like steroids. It can be used to synthesize chemical structures that are difficult to obtain by ordinary methods and as a model of mammalian metabolism due to similarity between mammalian and microbial enzyme systems. During recent years research has been focused on the structural modifications of bioactive steroids by using various microorganisms, in order to obtain biologically potent compounds with diverse structures. Steroidal compounds are responsible for important biological functions in the cells and manifest a variety of activities. This article covers the microbial transformation of sterols, steroidal hormones and some new types of steroids known as bufadienolides. Emphasis has placed on reporting metabolites that may be of general interest and on the practical aspects of work in the field of microbial transformations. The review covers the literature from 1994 to 2011.     

Application of cross-linked beta-cyclodextrin polymer for adsorption of aromatic amino acids

Beta-cyclodextrin (beta-CyD) was cross-linked by hexamethylene diisocyanate and the polymer was investigated for adsorption of aromatic amino acids (AAA) from phosphate buffer. High adsorption rates were observed at the beginning and the adsorption equilibrium was then gradually achieved in about 45 min. The adsorption of AAA decreased with the increase of initial concentration and also temperature. Under the same conditions, the adsorption efficiencies of AAA were in the order of L-tryptophan (L-Trp) > L-phenylalanine (L-Phe) > L-tyrosine (L-Tyr). Much higher adsorption values, up to 52.4 and 43.0 mg/g for L-Trp and L-Phe, respectively, at 50 mmol/L and 3.2 mg/g for L-Tyr at 2 mmol/L, were obtained with the beta-CyD polymer at 37 degrees C. It was shown that the adsorption of AAA on the beta-CyD polymer was consistent with the Freundlich isotherm equation. The adsorption of mixed aromatic amino acids and branched-chain amino acids (BCAA) showed that AAA were preferentially adsorbed with adsorption efficiencies 10-24%, while those of BCAA were lower than 2%. It seems that the structure and hydrophobicity of amino acid molecules are responsible for the difference in adsorption, by influencing the strength of interactions between amino acid molecule and the polymer.     

Synthesis and antiproliferative activity of some steroidal lactone compounds

Using cholesterol as starting material, some steroidal lactone compounds with the structures of 3-substituted-6-oxo-7-oxa-B-homo-cholestane or 3-substituted-7-oxo-6-oxa-B-homo-cholestane were synthesized by oxidation, reduction, Baeyer-Villiger reaction and condensation reaction. The cytotoxicity of these compounds against MGC 7901 (human gastric carcinoma), HeLa (human cervical carcinoma) and SMMC 7404 (human liver carcinoma) cells was investigated. Our results showed that the synthesized compounds displayed a distinct cytotoxicity against these cancer cells. In particular, compounds 8 and 9 have similar cytotoxic capability as cisplatin does. The information obtained from the studies may be useful for the design of novel chemotherapeutic drugs.     

Application of solid-phase extraction to agar-supported fermentation

Agar-supported fermentation (Ag-SF), a variant of solid-state fermentation, has recently been improved by the development of a dedicated 2 m² scale pilot facility, Platotex. We investigated the application of solid-phase extraction (SPE) to Ag-SF in order to increase yields and minimize the contamination of the extracts with agar constituents. The selection of the appropriate resin was conducted on liquid-state fermentation and Diaion HP-20 exhibited the highest recovery yield and selectivity for the metabolites of the model fungal strains Phomopsis sp. and Fusarium sp. SPE applied to Ag-SF resulted in a particular compartmentalization of the culture. The mycelium that requires oxygen to grow migrates to the top layer and formed a thick biofilm. The resin beads intercalate between the agar surface and the mycelium layer, and trap directly the compounds secreted by the mycelium through a “solid–solid extraction” (SSE) process. The resin/mycelium layer is easily recovered by scraping the surface and the target metabolites extracted by methanol. Ag-SF associated to SSE represents an ideal compromise for the production of bioactive secondary metabolites with limited economic and environmental impact.     

Automated solid-phase synthesis of linear nitrogen-linked compounds

A synthetic library motif has been developed to create linear, nitrogen-linked compounds as screening libraries to target structured RNA for drug discovery. Scaffolds were created in situ from suitably protected bifunctional compounds linked together either by acyl or amine links. Acyl links were created from amino acids, which also introduce one degree of functionality. Amine links from the amino acid nitrogen were created from an N-protected amino alcohol via Fukuyama Mitsunobu alkylation. Each amine site can then be used for introducing functionality or extending the scaffold. This synthetic scheme can be used to create a wide variety of modified-backbone PNA in situ, as shown by the synthesis of a PNA-type monomer. The synthesis steps have been enabled on a 96-well parallel-array synthesizer for high-throughput synthesis. The present study represents a versatile synthetic approach to a wide variety of potential RNA-binding molecules.     

Omega-pyridiniumalkylethers of steroidal phenols: new compounds with potent antibacterial and antiproliferative activities

Novel omega-pyridiniumalkylethers of two steroidal phenols were synthesized as compounds with potential antimicrobial activity. 3-Hydroxy-estra-1,3,5(10)-triene-17-one and 1-hydroxy-4-methyl-estra-1,3,5(10)-triene-17-one were reacted with omega,omega'-dibromoalkanes to omega-bromoalkoxy-estra-1,3,5(10)-trienes followed by reaction with pyridine to obtain the desired steroidal omega-pyridiniumalkoxy compounds as bromides. Their antimicrobial activity against strains of multiresistant Staphylococcus aureus (MRSA), a vancomycin resistant Enterococcus faecalis and fast growing mycobacteria depends clearly on the length of the alkyl chain. A strong broadband activity has been found for the compounds with eight or 10 C-atoms; in some cases better than ciprofloxacin or cetylpyridinium salts. In addition, the antiproliferative and cytotoxic activity depends on the chain length, too. The differentiation between antibacterial and cytotoxic activity is better for the steroid hybrid molecules than the cetylpyridinium salts. These new compounds can serve as lead compounds for further optimization.     

Synergie between molecular imprinted polymer based on solid-phase extraction and quartz crystal microbalance technique for 8-OHdG sensing

Recently, the 8-hydroxy-2'-deoxyguanosine (8-OHdG) has been used as a marker to determine the oxidative stress. There is no any cheap and easy determination method based on chips and sensor systems for the determination of 8-OHdG. In this study, we have proposed imprinting methods for 8-OHdG recognition and determination using methacryloylamidohistidine-platinum(II) [MAH-Pt(II)] as a new metal-chelating monomer. The study includes the solid-phase extraction (SPE) of blood sample by a new 8-OHdG imprinted sorbent and the measurement of binding interaction of 8-OHdG imprinted quartz crystal microbalance (QCM) sensor via ligand interaction. 8-OHdG imprinted sorbent has prepared by bulk polymerization of MAH-Pt(II) and N-N'-methylenebisacrylamide. 8-OHdG imprinted sensor has prepared on a QCM chip coating the thiol pretreated Au electrode. At the end of these steps, a thin molecular imprinted polymer (MIP) film for the detection of 8-OHdG has developed and analytical performance of QCM sensor which has prepared using MIP was investigated. The affinity constant (K(a)) for 8-OHdG using MAH-Pt-based thin film has determined by using the Scatchard method. The average percentage recovery of 8-OHdG from plasma samples was found as 80% by using of 8-OHdG imprinted SPE material. At the last step, 8-OHdG level in several blood plasma has been determined by this improved QCM sensor. The obtained results confirmed that the 8-OHdG level in cancer patient's blood was significantly higher than in general subjects.