Extraction of humic acids in two-phase aqueous polymeric systems

Extraction of humic acids isolated from various soils was studied in polyethylene glycol(NH₄)₂SO₄, polyethylene glycol-dextran, and polyethylene glycol-dextran sodium salt two-phase aqueous polymeric systems. It was shown that, in all systems, humic acids are extracted into the polyethylene glycolrich phase. It was studied how the composition of the extraction system, molecular weight of the polymer, and the sample nature affect the distribution ratios of humic acids.     

Extraction of the antimicrobial peptide cerein 8A by aqueous two-phase systems and aqueous two-phase micellar systems

Cerein 8A is an antimicrobial peptide with potential application against food spoilage and pathogenic bacteria. The partitioning of cerein 8A was investigated in two liquid-liquid extraction systems that are considered promising for bioseparation and purification purposes. Aqueous two-phase systems (ATPSs) were prepared with polyethylene glycol (PEG) and inorganic salts, and the addition of NaCl was investigated in this system. The best results concerning partition coefficients (K (b)) were obtained with PEG?+?ammonium sulphate, and K (b) value significantly increases when NaCl was added. Cerein 8A was effectively extracted into the micelle-rich phase in a 4% Triton X-114 medium. Recovery yield was higher for ATPS compared to micellar systems. Cerein 8A can be isolated from a crude suspension containing the bioactive molecule by ATPSs. Successful implementation of peptide partitioning represents an important step towards developing a low-cost effective separation method for cerein 8A.     

Mechanical composites based on biologically active compounds from larch wood

Mechanical composites were prepared by mechanical chemical processing of a mixture of biologically active preparations of arabinogalactan (AG) and dihydroquercetin (DQ) isolated from larch wood. Their properties were studied using HPLC, ¹³C NMR, and IR spectroscopy. It was found that AG and DQ did not react chemically under the studied conditions. According to x-ray phase and thermal analyses, mechanical processing destroyed the DQ crystalline structure and dispersed it into the AG matrix. The resulting mechanical composites had significantly higher (up to 38 times) solubility in water compared with starting DQ and an unprocessed AG/DQ mixture. It was shown that DQ reduces the extent of destruction of polysaccharide macromolecules during mechanical processing.     

Synthesis of biologically active compounds based on 2-ferrocenylmethylene-3-quinuclidone

Biologically active nitrogen heterocycles (1–7) containing ferrocene and quinuclidine fragments were synthesized. 3-Methylene-2-ferrocenylmethylenequinuiclidine forms adducts withN-phenylimides of azodicarboxylic (the structure was established by X-ray structural analysis) and malefic acids. 3-Methylene-2-fer-rocenylmethylenequinticlidine also undergoes [4+2]-cyclodimerization when heated and adds salts of the 3-methyl-2-ferrocenylmethyleneI-azoniabicyclo[2.2.2]oct-3-yl cation at the terminal methylene group to form a linear addition product.Instituto de Quimica, Universidad Nacional Autonoma de Mexico (UNAM), Circuito Exterior, Ciudad Universitaria, Coyoacan.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp 2743–2750, November, 1996.     

Silyl modification of biologically active compounds

A series of derivatives of (1,2,3,4-tetrahydro-1-quinolyl)-, (1,2,3,4-tetrahydro-2-isoquinolyl)-, and (1,2,3,4-tetrahydrosila-2-isoquinolyl)acetic acid, which are structural analogs of glycine, were synthesized. The psychotropic activity and the acute toxicity of the compounds were studied.For Communication 3, see [6].Latvian Institute of Organic Synthesis, Riga. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 270–274, February, 1997.     

Drop formation in aqueous two-phase systems

Extraction using aqueous two-phase systems (ATPSs) is a versatile technique for the downstream processing of various proteins/enzymes. The study of drop formation deals with the fundamental understanding of the behavior of liquid drops under the influence of various external body as well as surface forces. These studies provide a basis for designing of the extractions in column contactors in which liquid drops play a major role. Most of the drop formation studies reported so far is restricted to aqueous-organic systems. ATPSs, differ from aqueous-organic systems in their physical properties. In view of this, an attempt was made to develop a model for drop formation in ATPSs adopting the information available on aqueous-organic systems. In order to validate the model, experiments were performed by using polyethylene glycol (PEG)/salt systems of different phase compositions at various flow rates. At low flow rates the single stage model and at high flow rates the two stage model are able to predict the drop volume during its formation from tip of capillary. The experimental results were found to agree reasonably well with those predicted by the model.     

Microfluidics with aqueous two-phase systems

An overview is given about research activities in which aqueous two phase systems (ATPSs) are utilized in microfluidic setups. ATPSs consist of two immiscible aqueous phases and have traditionally been used for the separation and purification of biological material such as proteins or cells. Microfluidic implementations of such schemes are usually based on a number of co-flowing streams of immiscible phases in a microchannel, thereby replacing the standard batch by flow-through processes. Some aspects of the stability of such flow patterns and the recovery of the phases at the channel exit are reviewed. Furthermore, the diffusive mass transfer and sample partitioning between the phases are discussed, and corresponding applications are highlighted. When diffusion is superposed by an applied electric field normal to the liquid/liquid interface, the transport processes are accelerated, and under specific conditions the interface acts as a size-selective filter for molecules. Finally, the activities involving droplet microflows of ATPSs are reviewed. By either forming ATPS droplets in an organic phase or a droplet of one aqueous phase inside the other, a range of applications has been demonstrated, extending from separation/purification schemes to the patterning of surfaces covered with cells.     

Exploring the DNA binding mode of transition metal based biologically active compounds

Few novel 4-aminoantipyrine derived Schiff bases and their metal complexes were synthesized and characterized. Their structural features and other properties were deduced from the elemental analysis, magnetic susceptibility and molar conductivity as well as from mass, IR, UV-vis, (1)H NMR and EPR spectral studies. The binding of the complexes with CT-DNA was analyzed by electronic absorption spectroscopy, viscosity measurement, and cyclic voltammetry. The interaction of the metal complexes with DNA was also studied by molecular modeling with special reference to docking. The experimental and docking results revealed that the complexes have the ability of interaction with DNA of minor groove binding mode. The intrinsic binding constants (K(b)) of the complexes with CT-DNA were found out which show that they are minor groove binders. Gel electrophoresis assay demonstrated the ability of the complexes to cleave the pUC19 DNA in the presence of AH(2) (ascorbic acid). Moreover, the oxidative cleavage studies using distamycin revealed the minor groove binding for the newly synthesized 4-aminoantipyrine derived Schiff bases and their metal complexes. Evaluation of antibacterial activity of the complexes against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, and Klebsiella pneumoniae exhibited that the complexes have potent biocidal activity than the free ligands.     

具生物活性有机磷化合物的设计与合成

对氨基膦酸及磷肽的合成作了研究,同时考察了引入二氟次甲基及三氟甲基的方法。在此基础上研究成功基于[1,2]不对称诱导及[1,3]质子转移反应的手性合成方法。对多官能团的氨基膦酸及磷肽也作了研究。此外还制备了具1,1-双膦酸基的多种碳环化合物,对含磷酰基,特别对既含磷酰基又含三氟甲基的多种杂环化合物的合成方法与反应机理进行了报导。     

13C NMR spectra of biologically active compounds

The diastereomeric effects on the¹³C NMR chemical shifts of thirteen epimeric pairs of 16-aryloxy-11-deoxyprostaglandins of the E₁ and F₁ series caused by the change in the configuration of the 15-hydroxy group, which are differential parameters for assigning epimers to the 15- and 15-stereochemical series, have been determined.For Communication (VIII), see [1].Institute of Chemistry, Bashkir Scientific Center, Urals Branch, Academy of Sciences of the USSR, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 123–128, January–February, 1991.     

Water-soluble polymers for binding hydrophobic biologically active compounds

Russian Chemical Bulletin - Water-soluble neutral and charged copolymers of cholesterol methacrylate with 2-deoxy2-methacrylamido-D-glucose and methyl sulfate salt of N,N,N-trimethyl(aminoethyl...     

Electrochemical DNA-sensors for determining biologically active low-molecular compounds

General tendencies of the progress in the development of electrochemical DNA sensors devoted to the determination of biologically active low-molecular compounds have been considered on the base on own authors investigations and literary data. The ways for the generation of analytical signal of DNA sensors are considered depending on the mechanism of DNA- analyte interaction. The application of DNA sensors for the determination of pharmaceuticals (anthracyclines,. phenothiazines, sulfonylamides etc.) and environmental pollutants is described. The prospects of DNA sensor development are discussed.     

Germapharmaca: Some recent studies on biologically active organogermanium compounds

Recent research results on biologically active organogermanium compounds are described. Emphasis is placed on two categories based on (1) carbethoxyethylgermanium sesquioxide and (2) the ‘spirogermanium’ system. Other organogermanium derivatives covered include various mono-, di-, tri- and tetra-compounds. Mention is also made of organogermanium compounds as food additives and as the products of biological methylation.     

Structural features of biologically active coordination compounds of vanillinsemicarbazone

Summary Complexes of vanillinsemicarbazone (VSC) with Mn^II, Fe^II, Co^II, Ni^II, Cu^II, Zn^II, Cd^II and Hg^II have been prepared and characterised by elemental analyses, molar conductance, magnetic susceptibility and spectral data. Probable structures for the complexes are suggested on the basis of their physico-chemical properties. The fungitoxicity of VSC and the isolated complexes have been tested on pathogenic fungi. On leave from the University of Mysore, India.     

The Grandberg reaction in the synthesis of biologically active compounds

The review is focused on the Grandberg synthesis, namely, the synthesis of tryptamines from arylhydrazines and γ-halocarbonyl compounds, as an exceptionally useful and efficient methodology to access biologically active indole heterocycles.     

Electrophoretic transport of solutes in aqueous two-phase systems.

Electrophoretic transport of proteins across the interface between the phases of an aqueous polymer two-phase system can be greatly impeded in comparison with transport within the individual phase. This effect can be controlled by modifying the affinity of the protein for a phase by suitable manipulations of such variables as pH. The effect is not caused by differences in the electrophoretic velocity between the two phases, nor by large changes in pH at the interface. An analogy exists between this phenomenon and the related subject of diffusion of electrolytes across the phase interface.