An ion-selective crown ether covalently grafted onto chemically exfoliated MoS2 as a biological fluid sensor

We describe the basal plane functionalization of chemically exfoliated molybdenum disulfide (ce-MoS2) nanosheets with a benzo-15-crown-5 ether (B15C5), promoted by the chemistry of diazonium salts en route to the fabrication and electrochemical assessment of an ion-responsive electrode. The success of the chemical modification of ce-MoS2 nanosheets was investigated by infrared and Raman spectroscopy, and the amount of the incorporated crown ether was estimated by thermogravimetric analysis. Raman spatial mapping at on-resonance excitation allowed us to disclose the structural characteristics of the functionalized B15C5-MoS2 nanosheets and the impact of basal plane functionalization to the stabilization of the 1T phase of ce-MoS2. Morphological investigation of the B15C5-MoS2 hybrid was implemented by atomic force microscopy and high-resolution transmission electron microscopy. Furthermore, fast-Fourier-transform analysis and in situ energy dispersive X-ray spectroscopy revealed the crystal lattice of the modified nanosheets and the presence of crown-ether addends, respectively. Finally, B15C5-MoS2 electrodes were constructed and evaluated as ion-selective electrodes for sodium ions in aqueous solution and an artificial sweat matrix.

Ratiometric Detection of Mercury (II) Ions in Living Cells Using Fluorescent Probe Based on Bis(styryl) Dye and Azadithia-15-Crown-5 Ether Receptor

Bis(styryl) dye 1 bearing N-phenylazadithia-15-crown-5 ether receptor has been evaluated as a ratiometric fluorescent chemosensor for mercury (II) ions in living cells. In aqueous solution, probe 1 selectively responds to the presence of Hg²⁺ via the changes in the emission intensity as well as in the emission band shape, which is a result of formation of the complex with 1:1 metal to ligand ratio (dissociation constant 0.56 ± 0.15 µM). The sensing mechanism is based on the interplay between the RET (resonance energy transfer) and ICT (intramolecular charge transfer) interactions occurring upon the UV/Vis (380 or 405 nm) photoexcitation of both styryl chromophores in probe 1. Bio-imaging studies revealed that the yellow (500-600 nm) to red (600-730 nm) fluorescence intensity ratio decreased from 4.4 ± 0.2 to 1.43 ± 0.10 when cells were exposed to increasing concentration of mercury (II) ions enabling ratiometric quantification of intracellular Hg²⁺ concentration in the 37 nM-1 μM range.

Silicon Quantum Dot-Based Fluorescence Turn-On Metal Ion Sensors in Live Cells

Multiple sensor systems are designed by varying aza-crown ether moiety in silicon quantum dots (SiQDs) for detecting individual Mg(2+), Ca(2+), and Mn(2+) metal ions with significant selectivity and sensitivity. The detection limit of Mg(2+), Ca(2+), and Mn(2+) can reach 1.81, 3.15, and 0.47 μM, respectively. Upon excitation of the SiQDs which are coordinated with aza-crown ethers, the photoinduced electron transfer (PET) takes place from aza-crown ether moiety to the valence band of SiQDs core such that the reduced probability of electron-hole recombination may diminish the subsequent fluorescence. The fluorescence suppression caused by such PET effect will be relieved after selective metal ion is added. The charge-electron binding force between the metal ion and aza-crown ether hinders the PET and thereby restores the fluorescence of SiQDs. The design of sensor system is based on the fluorescence "turn-on" of SiQDs while in search of the appropriate metal ion. For practical application, the sensing capabilities of metal ions in the live cells are performed and the confocal image results reveal their promising applicability as an effective and nontoxic metal ion sensor.

[Metabolic research of domestically developed small molecule tyrosine kinase inhibitors]

Drug metabolism research plays an essential role in drug discovery and development. Great efforts have been made domestically to be line with the international standardized research on drug metabolism. In this article, we will review new-generation of tyrosine kinase inhibitors(TKIs), these TKIs include icotinib, apatinib, famitinib, flumatinb, allitinib, fruquintinib, and selatinib, among which icotinib and apatinib have been approved by China food and drug administration(CFDA) to reach the market, while others are in clinical trials. For these TKIs, the structural modified sites are active metabolic centers and CYP3A4 is identified as the primary metabolic enzyme. Considering the active intermediates, the crown ether ring of icotinib is oxidated to open to form an aldehyde; the indolylidene ring of famitinib is oxidated followed by rearrangement to form a quinone- imine; the α, β-unsaturated carbonyl group of allitinib is oxidated to form an epoxide, these intermediates are capable of covalently binding biomolecules and generating toxicity. In addition, human (14)C radioactive trials of most of these TKIs have not been conducted, and the data of drug-drug interactions in clinic are also absent, which indicate our deficiency compared to the international regular approaches in metabolic research.

Simultaneous column preconcentration of ultra trace amounts of heavy metals with nano-adsorbent in some environmental and biological samples

In the present investigation, multi-walled carbon nanotubes impregnated by 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane were prepared and applied as adsorbent for the simultaneous separation of Bi(III), Cu(II), Cd(II) and Pb(II) ions prior to their determination by electrothermal atomic absorption spectrometry. The following analytical figures of merit were determined for bismuth, copper, cadmium and lead, respectively: enrichment factors of 168, 134, 111 and 146, assay precisions of ±4.6%, ±4.8%, ±5.3% and ±5.0% and detection limits of 11.3, 3.7, 0.5 and 0.3 ng L(-1). The method was successfully applied for the determination of heavy metals in environmental, biological and certified reference materials.

Factors that influence competitive intermolecular solvation of protonated groups in peptides and proteins in the gas phase

The ability of 18-crown-6 (18C6) to form noncovalent complexes with cationic groups in the gas phase has been leveraged in numerous, largely orthogonal mass spectrometry-based applications. Although the fundamental interaction between 18C6 and a charged group in the gas phase is quite strong, the strength of attachment of 18C6 to large molecules is more difficult to predict because intramolecular binding of the cation can be competitive. Herein, we demonstrate in experiments with model peptides that 18C6 adducts are not strongly attached to flexible molecules with numerous potential hydrogen bonding sites. 18C6 adduct stability is increased if intramolecular charge complexation is inhibited by sterics or competitive binding. It is demonstrated with molecular mechanics that significant structural changes occur upon loss of 18C6 in model peptides. Examination of the loss of 18C6 adducts from proteins following collisional activation reveals that lower charge states lose the most 18C6. The degree of 18C6 adduct stability may reflect the degree of structural reorganization that occurs following collisional activation, suggesting that lower charge states represent structures that are not similar to gas phase idealized states. In this regard, 18C6 may serve the function of protecting solution phase protein structure. Collisional activation of holomyoglobin with 18C6 adducts attached reveals that heme loss occurs primarily after 18C6 loss, further supporting the notion that 18C6 protects native structure by solvating charged sites.

Hydrogel-based microactuators with remote-controlled locomotion and fast Pb2+-response for micromanipulation

Hydrogel-based microactuators that enable remote-controlled locomotion and fast Pb(2+)-response for micromanipulation in Pb(2+)-polluted microenvironment have been fabricated from quadruple-component double emulsions. The microactuators are Pb(2+)-responsive poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) microgels, each with an eccentric magnetic core for magnetic manipulation and a hollow cavity for fast Pb(2+)-response. Micromanipulation of the microactuators is demonstrated by using them for preventing Pb(2+)-leakage from microchannel. The microactuators can be remotely and precisely transported to the Pb(2+)-leaking site under magnetic guide, and then clog the microchannel with Pb(2+)-responsive volume swelling to prevent flowing out of Pb(2+)-contaminated solution. The proposed microactuator structure provides a potential and novel model for developing multifunctional actuators and sensors, biomimetic soft microrobots, microelectro-mechanical systems and drug delivery systems.

High-throughput capillary electrophoresis-mass spectrometry: from analysis of amino acids to analysis of protein complexes

Recent advances in capillary electrophoresis-mass spectrometry (CE-MS) interfacing using porous tip is leading to commercialization of CE-MS with a sheathless interface for the first time. The new sheathless interface in conjunction with CE capillary coatings using self-coating background electrolytes (BGE) has significantly simplified CE-MS analysis of complex mixtures. CE-MS, with its high separation efficiency, compound identification capability, and ability to rapidly separate compounds with a wide range of mass and charge while consuming only nanoliters of samples, has become a valuable analytical technique for the analysis of complex biological mixtures. These advances have allowed a single capillary to analyze a range of compounds including amino acids, their D/L enantiomers, protein digests, intact proteins, and protein complexes. With these capabilities, CE-MS is poised to become the multipurpose tool of separation scientists. More recently, an eight-capillary CE in conjunction with an 8-inlet mass spectrometry has allowed 8 CE-MS analyses to be performed concurrently, significantly increasing throughput.

Evaluation of polymer inclusion membranes containing crown ethers for selective cesium separation from nuclear waste solution

Transport behaviour of (137)Cs from nitric acid feed was investigated using cellulose triacetate plasticized polymer inclusion membrane (PIM) containing several crown ether carriers viz. di-benzo-18-crown-6 (DB18C6), di-benzo-21-crown-7 (DB21C7) and di-tert-butylbenzo-18-crown-6 (DTBB18C6). The PIM was prepared from cellulose triacetate (CTA) with various crown ethers and plasticizers. DTBB18C6 and tri-n-butyl phosphate (TBP) were found to give higher transport rate for (137)Cs as compared to other carriers and plasticizers. Effect of crown ether concentration, nitric acid concentration, plasticizer and CTA concentration on the transport rate of Cs was also studied. The Cs selectivity with respect to various fission products obtained from an irradiated natural uranium target was found to be heavily dependent on the nature of the plasticizer. The present work shows that by choosing a proper plasticizer, one can get either good transport efficiency or selectivity. Though TBP plasticized membranes showed good transport efficiency, it displayed poor selectivities. On the other hand, an entirely opposite separation behaviour was observed with 2-nitrophenyloctylether (NPOE) plasticized membranes suggesting the possible application of the later membranes for the removal of bulk (137)Cs from the nuclear waste. The stability of the membrane was tested by carrying out transport runs for nearly 25 days.

Novel heavy-metal adsorption material: ion-recognition P(NIPAM-co-BCAm) hydrogels for removal of lead(II) ions

A novel polymeric lead(II) adsorbent is prepared by incorporating benzo-18-crown-6-acrylamide (BCAm) as metal ion receptor into the thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) hydrogel. Both stimuli-sensitive properties and the Pb(2+)-adsorption capabilities of the prepared P(NIPAM-co-BCAm) hydrogels are investigated. The prepared P(NIPAM-co-BCAm) hydrogels exhibit good ion-recognition and Pb(2+)-adsorption characteristics. When crown ether units capture Pb(2+) and form BCAm/Pb(2+) host-guest complexes, the lower critical solution temperature (LCST) of the hydrogel shifts to a higher temperature due to both the repulsion among charged BCAm/Pb(2+) groups and the osmotic pressure within the hydrogel. The adsorption results at different temperatures show that P(NIPAM-co-BCAm) hydrogels adsorb Pb(2+) ions at temperature lower than the LCST, but undergo desorption at temperature higher than the LCST due to the "stretch-to-shrink" configuration change of copolymer networks which is triggered by the change in environmental temperature. This kind of ion-recognition hydrogel is promising as a novel adsorption material for adsorption and separation of Pb(2+) ions. The adsorption and desorption of Pb(2+) could be rationally achieved by simply changing the environmental temperature.

Development of a carbon paste electrode containing benzo-15-crown-5 for trace determination of the uranyl ion by using a voltammetric technique

The interaction of macrocyclic compounds like crown ethers and UO2(2+) has been studied by electrochemical methods. A modified carbon paste electrode incorporating benzo-15-crown-5 (B15C5) was used to evaluate the electron transfer reaction of UO2(2+) by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Electrochemical impedance studies showed that charge transfer resistance was less for the B15C5-modified electrode than for the plain carbon paste electrode (PCPE). On the basis of these observations, a UO2(2+)-sensitive crown ether chemically modified electrode (CME) for trace analysis was fabricated and investigated in aqueous solutions. It was found that a 5% B15C5-CME for UO2(2+) showed a better voltammetric response than did the PCPE. UO2(2+) could be quantified at sub-microg/mL levels by differential pulse voltammetry with a detection limit of 0.03 microg/mL. By differential pulse adsorptive stripping voltammetry, UO2(2+) could be quantified in the working range of 0.002-0.2 microg/mL, with a detection limit of 1.1 microg/L. Simultaneous determination of UO2(2+), Pb(2+), and Cd(2+) was possible. The method was successfully applied to the determination of UO2(2+) in synthetic, as well as real, samples; the results were found to be comparable to those obtained by inductively coupled plasma-atomic emission spectroscopy.

Liquid chromatographic direct resolution of β-amino acids on a doubly tethered chiral stationary phase containing NH amide linkage based on (+)-(18-crown-6)- 2,3,11,12-tetracarboxylic acid

A doubly tethered chiral stationary phase (CSP) prepared by bonding (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid to doubly tethered primary aminoalkyl silica gel was used for the resolution of various beta-amino acids. All the beta-amino acids tested were resolved quite well, the separation (alpha) and the resolution factors (RS) being in the ranges 1.34-2.09 and 2.52-7.45, respectively, with a mobile phase of methanol-water (50:50, v/v) containing 10 mM acetic acid. The chiral recognition efficiency of the doubly-tethered CSP was found to be generally superior to that of the corresponding singly-tethered CSP in the resolution of beta-amino acids. The chiral recognition behaviors for the resolution of beta-amino acids on the doubly tethered CSP were examined by varying the type and content of organic and acidic modifiers in the aqueous mobile phase and the column temperature.

Chiral NMR discrimination of amines: Analysis of secondary, tertiary, and prochiral amines using (18-crown-6)-2,3,11,12-tetracarboxylic acid

Enantiomeric discrimination is observed in the 1H and 13C NMR spectra of secondary and tertiary amines in the presence of (-)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (1). Nonequivalence of the resonances of prochiral nuclei in primary and secondary amines is also observed when they associate with 1. The amines are added in their neutral form and are protonated by the carboxylic acid groups of 1 to produce the corresponding ammonium and carboxylate ions. Secondary amines associate with 1 through two hydrogen bonds and an ion pair interaction. Tertiary amines can only form one hydrogen bond to accompany the ion pairing. Chiral discrimination in the 1H and 13C NMR spectra of a series of aryl-containing secondary amines is of sufficient magnitude to determine enantiomeric purities. The discrimination in the spectra of tertiary amines with 1 is smaller, but 13C NMR spectra provided enough distinction for the determination of enantiomeric purity.

Stereoisomeric separation of pharmaceutical compounds using CE with a chiral crown ether

Optical pure (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid, a chiral crown ether, was successfully used as a chiral selector for the stereoisomeric separation of numerous real pharmaceutical compounds. Both practical and mechanistic aspects were described. Effects of chiral selector concentration under different pH values of BGE were discussed. Chiral recognition for the enantiomeric compounds with (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid was investigated through model compounds using CE and infrared spectroscopic techniques. Relations between the enantioselectivity of the chiral crown ether and the structural features of the studied compounds were also investigated. Unusual resolutions of compound-p and its enantiomer as well as compound-o and its 2b epimer were described. These compounds contained only tertiary amine, believed to be nonbinding with crown ethers in general. The possible mechanisms for the interaction between compound-o and the chiral crown ether were investigated using CE, electrospray MS (ESI-MS), and proton ((1)H) NMR spectroscopy. All experiments provided clear evidence that binding between compound-o and the chiral crown ether had occurred. ESI-MS spectra indicated that the complexes had a 1:1 stoichiometric ratio. The advantages and disadvantages of using chiral crown ether for stereoisomeric separations were compared with those using sulfated CDs.

Molecular modelling approaches to host-guest complexes

Host-guest interactions can be modelled as a non-bonding recognition process using long-range electrostatic forces. By using molecular isopotential maps the differences between the methotrexate-dihydrofolate reductase and folate-dihydrofolate reductase complexes can be predicted. By extending the technique to molecule-molecule docking the interaction of formamide with the crown ether 18-crown-6 can be simulated with reasonable accuracy. The closely related problem of predicting the separation of enantiomers of chiral molecules by chromatography has been attempted with encouraging results. A preliminary report is presented on the progress being made towards a better model for simulating stacking arrangement of pi systems by charge distribution.

Visible fluorescence chemosensor for saxitoxin

Absorption spectra of a number of shellfish extracts have been obtained and reveal prominent absorptions in all samples at 210 and 260 nm and at 325 nm in some of them. These absorptions preclude the use of chromophores with similar absorptions in testing of shellfish samples for paralytic shellfish toxins. Two crown ether chemosensors featuring a boron azadipyrrin chromophore have been synthesized; both have absorption maxima at 650 nm, where all the shellfish extracts are transparent. The synthetic sensors feature either 18- or 27-membered crown ether rings and have been evaluated as visible sensors for the paralytic shellfish toxin saxitoxin. The binding constant for one of them is in the range of 3-9x10(5) M-1 and exhibits a fluorescence enhancement of over 100% at 680 nm in the presence of 40 microM saxitoxin.

Adsorption of copper and lead in aqueous solution onto bentonite modified by 4'-methylbenzo-15-crown-5

The adsorption of heavy metal ions (Cu2+ and Pb2+) onto organobentonite modified by 4'-methylbenzo-15-crown-5 (MB15C5) from bentonite compared with natural bentonite (N-Bentonite) is described in this paper. The kinetic parameters of the models are calculated and discussed, and closely fitted a pseudo-second-order model in all cases. For bentonite modified with MB15C5 (MB15C5-Bentonite) and N-Bentonite, the equilibrium data closely fitted the Langmuir model and showed the following affinity order: Pb2+ > Cu2+, and the adsorption capacity of MB15C5-Bentonite is higher than that of N-Bentonite for Pb2+ and Cu2+. The effect of pH is examined over the range 1.5-6. The adsorption of Cu2+ and Pb2+ increases with increasing pH and the adsorption of Cu2+ and Pb2+ reaches a maximum at pH 3.5-6.

Liquid chromatographic enantiomer resolution ofN-hydrazide derivatives of 2-aryloxypropionic acids on a crown ether derived chiral stationary phase

The liquid chromatographic separation of the enantiomers of several N-hydrazide derivatives of 2-aryloxypropionic acids was performed on a crown ether type chiral stationary phase derived from (18-crown-6)-2,3,11,12-tetracarboxylic acid. The behavior of chromatographic parameters by the change of mobile phases and additives for the resolution of these analytes was investigated. The enantiomers of all analytes were base-line resolved with a mobile phase of 100% methanol containing 20 mM H2SO4. These results are the first reported for enantiomer resolution of chiral acids of 2-aryloxypropionic acids as their N-hydrazide derivatives.

Crown Ether-Mediated Extraction and Functional Conversion of Cytochrome c in Ionic Liquids

We report that a macrocyclic ligand enables transfer of a protein from an aqueous phase to ionic liquids. The extraction behavior of heme protein cytochrome c (Cyt-c) from an aqueous phase into ionic liquids was investigated with crown ethers. A hydroxyl-group-containing ionic liquid with dicyclohexano-18-crown-6 was found to be capable of quantitative partitioning of Cyt-c, whereas the protein transfer using conventional organic solvents was negligibly small. Furthermore, we clarified that Cyt-c solubilized in ionic liquids caused a structural transformation of Cyt-c, which triggers its functional conversion from an electron-transfer protein to peroxidase.

Enantioseparation of aromatic amino acids and amino acid esters by capillary electrophoresis with crown ether and prediction of enantiomer migration orders by a three-dimensional quantitative structure-property relationship/comparative field analysis model

The complete enantioseparations of eight aromatic amino acids and four alkyl esters of 2-phenylglycine were achieved by chiral capillary electrophoresis employing 20 mM Tris-citric acid background electrolyte (pH 2.50) containing 5.0 mM of (+)-18-crown-6-tetracarboxylic acid. The relative migration times (RMTs) to that of 6-aminonicotinic acid were characteristic of each enantiomer with good within-day precisions (% relative standard deviation (RSD) < or = 2.0). Quantitative structure-property relationship (QSPR) modeling based on comparative molecular field analysis (CoMFA) was performed to investigate the correlation between the molecular field descriptor values of each enantiomer studied as analyte and its RMT. The resulting CoMFA model allowed reliable prediction for the RMT values (q2= 0.406, r2 = 0.996), thus being expected to become a valuable tool to predict enantiomer migration orders (EMOs) of amino acids and amines whose pure enantiomers are unavailable. The CoMFA steric fields supported the well-established chiral recognition mechanism based on molecular interaction between chiral selector (+)-18-crown-6-tetracarboxylic acid and amino acid enantiomers.

Development of a capillary electrophoretic method for the separation of diastereoisomers of a new human immunodeficiency virus protease inhibitor

A capillary electrophoretic (CE) method was developed for the separation of diastereoisomers of a new human immunodeficiency virus (HIV) protease inhibitor TMC114. In total 16 isomers of this drug have been synthesized (eight pairs of enantiomers). We succeeded in the separation of the eight diastereoisomers, but no enantiomers could be separated. Because of the high similarity and water-insolubility of these isomers, the separation is a real challenge. Different CE modes were tried out: capillary zone electrophoresis (CZE), nonaqueous capillary electrophoresis (NACE), micellar electrokinetic capillary chromatography (MEKC), and microemulsion electrokinetic capillary chromatography (MEEKC). Only MEEKC offered resolution of these compounds.

Liquid chromatographic enantioseparation of aryl?-amino ketones on a crown ether-based chiral stationary phase

A liquid chromatographic chiral stationary phase based on (3,3'-diphenyl-1,1'-binaphthyl)-20-crown-6 covalently bonded to silica gel was applied in the resolution of aryl alpha-amino ketones including cathinone, the main psychoactive alkaloid found in the leaves of the khat plant. The resolution was excellent, the separation factors ranging between 1.72 and 8.58 and the resolution factors (R(S)) ranging between 2.60 and 11.10. The chromatographic resolution behaviour was dependent on the type and the content of organic and acidic modifiers and the ammonium acetate concentration in aqueous mobile phase and the column temperature.

Synthesis and characterization of covalently immobilized bis-crown ether based potassium ionophore

The synthesis of a novel covalently immobilized crown ether based potassium ionophore is presented. Apart from previously proposed methods for the preparation of PVC linked ionophores based on the chemical modification of functionalized PVC polymers, the hereby proposed procedure involves the direct copolymerization of a suitable derivative of the bis-crown ether type potassium ionophore (BME 44) and vinyl chloride monomer. The analytical performance of the potentiometric ion selective electrodes incorporating the PVC bound ionophore were optimized and determined. Compared with electrodes based on other bis-crown ether type immobilized potassium selective ionophores a slightly improved logK(K, Na)(Pot) and a longer lifetime was found. Spectral imaging and chronoamperometry were used to study the mobility of different bis-crown ether derivatives in plasticized PVC membranes.

In vivo determination of tumor oxygenation during growth and in response to carbogen breathing using 15C5-loaded alginate capsules as fluorine-19 magnetic resonance imaging oxygen sensors

PURPOSE

The objective was to present a method for the repeated noninvasive measurement of tumor oxygenation (Po(2)) over the whole period of tumor growth.

METHODS AND MATERIALS

A mixture of tumor homogenate (GH3 prolactinoma) and alginate capsules loaded with perfluoro-15-crown-5-ether (15C5) was injected into the flanks of Wistar Furth rats. The temporal behavior of tumor Po(2) was monitored between Day 1 and 26 after injection using fluorine-19 ((19)F) magnetic resonance imaging (MRI). In addition, the response of tumor Po(2) to modifiers of the tumor microenvironment (carbogen [95% O(2)/5% CO(2)], nicotinamide, and hydralazine) was investigated.

RESULTS

An initial increase of tumor Po(2), probably reflecting neovascularization, followed by a decrease after Week 2, probably indicating tumor hypoxia or necrosis, were observed. The minimum and maximum average Po(2) +/- SEM observed were 3.3 +/- 2.0 mm Hg on Day 2 and 25.7 +/- 3.8 mm Hg on Day 13, respectively. Carbogen increased the tumor Po(2), whereas nicotinamide caused no significant change and hydralazine induced a significant decrease in tumor oxygenation.

CONCLUSIONS

A preclinical method for the repeated noninvasive determination of tumor Po(2) was presented. It might help to investigate tumor physiology and the mechanisms of modifiers of the tumor microenvironment and their role in different therapeutic approaches.

Biological activity of bacterial lectins and their molecular complexes with heterocyclic bis-adducts

A new convenient method for the preparation of heterocyclic bis-adducts: of imidazole, benzimidazole, uracile with 1,1,1-trifluoro-2-bromo-2-chloroethane is described. The reactions are catalysed by the 18-crown-6-complex. The critical toxicity and antitumour activity of saprophytic strains Bacillus genus (B. subtilis 668 IMV and B. polymyxa 102 KSU) extracellular lectins were studies. It was discovered that these substances apply to a few toxic preparations and have a expression antitumour action on the tumours: Walker carcinosarcoma 256, Pliss' lymphosarcoma and Sarcoma 45. The new molecular complexes were created with bacterial lectins and the same heterocyclic-bis-adducts of unsubstituted benzimidazole and 6-methyluracile. A strongly antitumour effect of these complexes has been discovered: of growth relaxation of Pliss' lymphosarcoma tumour mass was 62.5-82.01%.