Vyacheslav S. Grinev

The coupling of the plant and microbial catabolisms of phenanthrene in the rhizosphere of Medicago sativa.

We studied the catabolism of the polycyclic aromatic hydrocarbon phenanthrene by four rhizobacterial strains and the possibility of enzymatic oxidation of this compound and its microbial metabolites by the root exudates of alfalfa (Medicago sativa L.) in order to detect the possible coupling of the plant and microbial metabolisms under the rhizospheric degradation of the organic pollutant. A comparative study of phenanthrene degradation pathways in the PAH-degrading rhizobacteria Ensifer meliloti, Pseudomonas kunmingensis, Rhizobium petrolearium, and Stenotrophomonas sp. allowed us to identify the key metabolites from the microbial transformation of phenanthrene, including 9,10-phenanthrenequinone, 2-carboxybenzaldehyde, and 1-hydroxy-2-naphthoic, salicylic, and o-phthalic acids. Sterile alfalfa plants were grown in the presence and absence of phenanthrene (0.03 g kg(-1)) in quartz sand under controlled environmental conditions to obtain plant root exudates. The root exudates were collected, concentrated by ultrafiltration, and the activity of oxidoreductases was detected spectrophotometrically by the oxidation rate for various substrates. The most marked activity was that of peroxidase, whereas the presence of oxidase and tyrosinase was detected on the verge of the assay sensitivity. Using alfalfa root exudates as a crude enzyme preparation, we found that in the presence of the synthetic mediator, the plant peroxidase could oxidize phenanthrene and its microbial metabolites. The results indicate the possibility of active participation of plants in the rhizospheric degradation of polycyclic aromatic hydrocarbons and their microbial metabolites, which makes it possible to speak about the coupling of the plant and microbial catabolisms of these contaminants in the rhizosphere.

Crystal structure of 3-(2-(2-nitrophenyl)hydrazono)-5-phenyl-3H-furan-2-one

The X-ray crystallographic method is used to determine the crystal structure and characteristic features of the molecular structure of 3-(2-(2-nitrophenyl)hydrazono)-5-phenyl-3H-furan-2-one produced by the reaction of azo coupling of 2-nitrophenyldiazonium salt with 5-phenyl-3Н-furan-2-one.

Structural studies of the polysaccharides from the lipopolysaccharides of Azospirillum brasilense Sp246 and SpBr14

Lipopolysaccharides from closely related Azospirillum brasilense strains, Sp246 and SpBr14, were obtained by phenol-water extraction. Mild acid hydrolysis of the lipopolysaccharides followed by GPC on Sephadex G-50 resulted in polysaccharide mixtures. On the basis of sugar and methylation analyses, Smith degradation and (1)H and (13)C NMR spectroscopy data, it was concluded that both bacteria possess the same two distinct polysaccharides having structures 1 and 2: [structure: see text]. Structure 1 has been reported earlier for a polysaccharide of A. brasilense 54 [Fedonenko et al., 2011] whereas to our knowledge structure 2 has not been hitherto found in bacterial polysaccharides.

Reaction of 4-oxocarboxylic acids and 5-substituted 3H-furan-2-ones with 1,2-binucleophiles of aromatic and alicyclic series

Based on reactions of 5-substituted 3H-furan-2-ones or 4-oxocarboxylic acids with 1,2-binucleophiles of aromatic and aliphatic series methods were developed for the synthesis of tricyclic structures containing a pyrrolidine fragment fused with imidazolidine or oxazolidine ring. The pathways of the reactions are considered. It was demonstrated that the nature of the substrate did not affect the reaction direction, but changed the scheme of the interaction. The structures of compounds obtained for the first time were proved using IR and 1H NMR spectra.

Degradation of fluorene and fluoranthene by the basidiomycete Pleurotus ostreatus

The dependence of the degree of fluorene and fluoranthene degradation by the fungus Pleurotus ostreatus D1 on the culture medium composition has been studied. Polycyclic aromatic hydrocarbons (PAHs) have been transformed in Kirk’s medium (under conditions of laccase production) with the formation of a quinone metabolite and 9-fluorenone upon the use of fluoranthene and fluorene as substrates, respectively. More complete degradation with the formation of an intermediate metabolite, phthalic acid that has undergone subsequent utilization, has occurred in basidiomycete-rich medium (under the production of both laccase and versatile peroxidase). The formation of phthalic acid as a metabolite of fluoranthene degradation by lignolytic fungi has been revealed for the first time. The data allow the supposition that both extracellular laccase and laccase on the mycelium surface can participate in the initial stages of PAH metabolism, while versatile peroxidase is necessary for the oxidation of the formed metabolites. A scheme of fluorene metabolism by Pleurotus ostreatus D1 is suggested.

Gas-liquid chromatography-obtained differences in the dissolution enthalpy between two positional isomers in a polar stationary phase: a measure of the inter- or intramolecular hydrogen bond energy?

Previous GLC work with several 2- and 4-substituted phenols and anilines, as well as with a pyrrolizidine alcohol, had determined the difference between the heats of dissolution of two positional isomers in a strong polar stationary liquid phase; one of these isomers forms an intramolecular hydrogen bond (intra-HB) and the other has no such bond for steric reasons. The energies of the intermolecular hydrogen bonds (inter-HBs), ΔH(inter-HB), formed by the 1,2- and 1,4-isomers with the molecules of a polar phase had been assumed approximately equal, so the difference between them could be ignored. The same assumption had been made for the energies of nonspecific interactions (NSIs), ΔH(NSI). It had been concluded that the found difference can be considered as an intra-HB energy (enthalpy), ΔH(intra-HB), when the energies (enthalpies) of inter-HBs formed by the 1,2- and 1,4-isomers under study with the molecules of a polar phase are much greater in absolute value than ΔH(intra-HB). And, conversely, when |ΔH(intra-HB)|>|ΔH(inter-HB)|, an inter-HB enthalpy will result. With the same assumptions, we here obtained an extended thermodynamic equation and corrected this above conclusion on the basis of a general consideration of the dissolution thermodynamics for two isomers of a molecule in a polar phase. Account was taken of the coefficients of isomer partitioning between the liquid and the gaseous phase at the experimental temperature. The conclusion made previously was adjusted for ΔH(NSI) and formulated as follows: The GLC method determines the intra-HB energy at |ΔH(intra-HB)|≤|ΔH(inter-HB)+ΔH(NSI)|. If |ΔH(intra-HB)|>|ΔH(inter-HB)+ΔH(NSI)|, the method yields the values of ΔH(inter-HB)+ΔH(NSI). This new conclusion was illustrated with virtual (numerical) experiments in which various ΔH(intra-HB), ΔH(inter-HB), and ΔH(NSI) values were postulated and results were obtained that would have been achieved by GLC if it had been done. Using a capillary column with the PEG 20M stationary phase, we measured the differences between the heats of dissolution for six pairs of isomers of phenolic compounds and for seven pairs of disubstituted benzene derivatives, which have similar structures but cannot form an intra-HB. The benzene derivatives served to make an approximate experimental estimate of the difference between the energies of NSIs of the isomers under study with a polar phase, ΔH(NSI).

Study of E/Z isomerization of (arylamino)methylidenefuran-2(3H)-ones by 1H, 13C, 15N spectroscopy and DFT calculations in different solvents: Study of E/Z isomerization of (arylamino)methylidenefuran-2(3H)-ones

The structure and configuration of the series of previously unknown arylaminomethylidenefuran‐2(3H)‐ones have been determined in solution by 1H, 13C, 15N nuclear magnetic resonance spectroscopy including two‐dimensional experiments such as 1H─1H COSY, dqCOSY, 1H─13C HSQC, 1H─13C HMBC. It was found that synthesized substances exist as an equilibrium mixture of E‐ and Z‐enamines in solution. It was established on the basis of density functional theory calculations that the exchange between the two push–pull enamines is a simple rotation around an exocyclic partial double bond that depends on the effect of the solvents. Copyright

Synthesis of 1-substituted 5-alkyl(aryl)-1,3-dihydro-2H-pyrrol-2-ones. Azocoupling with diazonium salts

Reactions of 5-alkyl- and 5-aryl-3H-furan-2-ones with 1,3- and 1,4-binucleophiles of aromatic series were carried out for the first time under various conditions. In the presence of a base the reaction resulted in 1-R-1,3-dihydro-2Н-pyrrol-2-ones, under milder conditions intermediates were isolated, 4-aryl-4-oxobutanamides. The structure of the latter was proved by spectral methods. By an example of 1-R-1,3-dihydro-2Н-pyrrol-2-ones the possibility was demonstrated of their functionalization via introducing an aryldiazenyl fragment.

Reaction of 5-alkyl- and 5-arylfuran-2(3H)-ones with aliphatic amino acids

Amino acids are polyfunctional reagents allowing target-oriented synthesis of various heterocyclic structures. The reaction of cysteine with levulinic acid gives a dibasic acid which readily loses water at elevated temperature, yielding bicyclothiazinone [1]. In the reaction of cysteine with 5-methylfuran-2(3H)-one, the amino acid initially adds to the double bond in the furan ring, and opening of the latter and subsequent dehydration lead to heterocyclic compound. The product is stabilized via further dehydration with formation of 5-oxothiazolidinecarboxylic acid [2]. The reaction of furan-2(3H)-one with L-cysteine involves initial attack by the amino group on the carbonyl carbon atom to produce oxo acid amide which is converted in solution into bicyclic hexahydropyrrolothiazole structure [3, 4]. Levulinic and β-benzoylpropionic acids were reported to react with anthranilic acid on heating in dichlorobenzene to produce 3a-methyland 3a-phenyl3,3a-dihydro-5H-benzo[d]pyrrolo[1,2-b][1,3]oxazine1,5(2H)-diones, respectively [5, 6]. In the reactions of anthranilic acid amide with levulinic and β-benzoylpropionic acids on heating in chlorobenzene 3a-methyland 3a-phenyl-2,3,3a,4-tetrahydropyrrolo[1,2-a]quinazoline-1,6-diones were obtained, respectively. Binucleophilic α-amino acids (cysteine, penicillamine, serine, and threonine) were studied in reactions

The degradative activity and adaptation potential of the litter-decomposing fungus Stropharia rugosoannulata

The ability of the litter-decomposing basidiomycete Stropharia rugosoannulata DSM 11372 to degrade a wide range of structurally different environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs: phenanthrene, anthracene, fluorene, pyrene, and fluoranthene), synthetic anthraquinone dyes containing condensed aromatic rings, environmentally relevant alkylphenol and oxyethylated alkylphenol representatives, and oil was demonstrated within the present study. 9,10-Anthraquinone, phenanthrene-9,10-quinone, and 9-fluorenone were identified as products of anthracene, phenanthrene, and fluorene degradation, respectively. Fungal degradation was accompanied by the production of the ligninolytic enzymes: laccase and Mn peroxidase, suggesting their involvement in pollutant degradation. Extracellular polysaccharide(s) (EPS) and emulsifying compound(s) were concomitantly produced. EPS composed of mannose, glucose, and galactose was isolated from the cultivation medium, and its effects on catalytic properties of purified laccase from S. rugosoannulata (the dominating ligninolytic enzyme under the applied conditions) were studied. A simultaneous decrease of KM and Vmax values observed for the enzymatic oxidation of non-phenolic (2,2-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt; ABTS) and phenolic compounds (2,6-dimethoxyphenol) in presence of EPS suggest an interaction of EPS and laccase resulting in a modulation of the catalytic performance of the enzyme, which has, to the best of our knowledge, not been reported before. In line with such a modulation, the laccase-catalyzed oxidation of natural aromatic compounds (veratryl alcohol, adlerol) and environmental pollutants (the alkylphenol representative nonylphenol, the diphenylmethane derivative bisphenol A, and the PAH representative anthracene) was found to be enhanced in presence of EPS. The relevance of such effects for real environmental processes and their implications remain to be investigated.Graphical abstract