High-throughput quantification of lincomycin traces in fermentation broth of genetically modified Streptomyces spp. Comparison of ultra-performance liquid chromatography and high-performance liquid chromatography with UV detection

A new separation and quantification method using ultra-performance liquid chromatography (UPLC) with UV detection was developed for detection of lincomycin traces in fermentation broth of different Streptomyces spp. A similar high-performance liquid chromatography (HPLC) protocol was simultaneously developed for comparison purposes. Both methods were validated and showed a linear range of detector response for quantification of lincomycin in concentration from 3.125 to 1000.0 microgml(-1) with correlation coefficient 0.999 and recoveries ranging from 81.5 to 89.85% with precision < or =5%. Compared with the HPLC, the UPLC method offered high sample throughput and about 10 times lower consumption of solvents. The developed assays were used for determination of lincomycin production in genetically manipulated production strain Streptomyces lincolnensis and for determination of lincomycin production after heterologous expression of lincomycin biosynthetic gene cluster in non-producing strain Streptomyces coelicolor.     

Existence and reactivity of three forms of orthophthalaldehyde in aqueous solutions. Polarographic, voltammetric, and spectrophotometric study

Orthophthalaldehyde (1,2-dicarboxaldehyde) (OPA) forms in the presence of a strong nucleophile with amino acids isoindole derivatives. The reaction is used in fluorometric determination of amino acids. The mechanism of these processes is not understood. OPA is present in aqueous solutions in three forms: unhydrated (I(a)), monohydrated acyclic (I(b)), and cyclic hemiacetal (I(c)). The absence of data for the molar absorptivities of these forms, together with overlap of their absorption bands, limits the application of spectrophotometry. Measurement of polarographic limiting currents of forms I(a) and I(b) enables determination of equilibrium constants K1 (formation of I(b)) and K2 (for the ring formation). The presence of these forms was supported by 1H NMR and 13C NMR. The rate of hydration of OPA is general-acid-base-catalyzed, but that of dehydration shows only specific-acid-base catalysis. The rate of hydration is controlled by general-acid-base-catalyzed addition of water to I(a). The rate of dehydration depends on the opening of the ring in I(c), which is specific-acid-base-catalyzed. At pH > 10 OPA undergoes a complex set of acid-base reactions (Scheme 3). The presence of polarographic anodic waves and oxidation on the gold electrode indicates the importance of the presence of a geminal diol form (II(a)). Establishment of equilibria among the three forms of OPA together with reactions at pH > 10 has to be considered in elucidating the reaction scheme of procedures using OPA as a reagent in the determination of amino acids.     

Advanced Analysis of Isobaric Heat Capacities by Mathematical Gnostics

Two novel imidazolium based ether-functionalized room temperature ionic liquids were synthesized to study the temperature dependence of the isobaric heat capacity in the temperature range 298.15–348.15 K. In-house synthesized ionic liquids are often available in small amounts only, owing to the high cost of the precursors and difficulties during the synthesis itself. It is therefore impossible to repeat measurement many times so that a statistically significant data sample can be obtained. In addition, to obtain at least several values of the measured property, the ionic liquid must be recycled and reused. In this work two recycling techniques were used and their influence on the values of the experimental isobaric heat capacity was analyzed. Advantages of a modern nonstatistical data analysis technique, namely mathematical gnostics, were demonstrated.     

Interior regularity of space derivatives to an evolutionary,symmetric $$\varphi $$-Laplacian

We consider the Orlicz-growth generalization to the evolutionary p-Laplacian and to the evolutionary symmetric p-Laplacian. We derive the spatial second-order Caccioppoli-type estimate for a local weak solution to these systems. Our result is new even for the p-case.     

Contribution to cation–π interaction of the univalent silver cation with racemic [7]helicene in the solid state

Structural Chemistry - Yellow crystals of the complex [7]helicene–silver perchlorate (i.e., C30H18–AgClO4 or more accurately [Ag(η4-C30H18)]ClO4, respectively), crystallizing in...     

Colored graphs without colorful cycles

A colored graph is a complete graph in which a color has been assigned to each edge, and a colorful cycle is a cycle in which each edge has a different color. We first show that a colored graph lacks colorful cycles iff it is Gallai, i.e., lacks colorful triangles. We then show that, under the operation mon ≡ m + n − 2, the omitted lengths of colorful cycles in a colored graph form a monoid isomorphic to a submonoid of the natural numbers which contains all integers past some point. We prove that several but not all such monoids are realized. We then characterize exact Gallai graphs, i.e., graphs in which every triangle has edges of exactly two colors. We show that these are precisely the graphs which can be iteratively built up from three simple colored graphs, having 2, 4, and 5 vertices, respectively. We then characterize in two different ways the monochromes, i.e., the connected components of maximal monochromatic subgraphs, of exact Gallai graphs. The first characterization is in terms of their reduced form, a notion which hinges on the important idea of a full homomorphism. The second characterization is by means of a homomorphism duality. The first author would like to express his thanks for support by project LN 00A056 of the Ministry of Education of the Czech Republic. The second author would like to express his thanks for support by project LN 00A056 of the Ministry of Education of the Czech Republic, by the NSERC of Canada and by the Gudder Trust of the University of Denver.     

1,8,9-Substituted anthracenes, intramolecular phosphine donor stabilized metaphosphonate and phosphenium

A series of 1,8,9-tris(phosphorus) substituted anthracenes was synthesised and fully characterised. Their molecular geometry is such that the middle phosphorus atom is in a highly congested space, with terminal phosphorus atoms in close proximity. The middle phosphorus atom accepts electron density from none, one or both terminal phosphorus atoms to form P-P bonds. Thus phosphino (repulsively interacting), metaphosphonato (single donor stabilised) as well as phosphenium (doubly phosphine donor stabilised) environments around the phosphorus atom in position 9 were synthesized and structurally characterised. Observed P[dot dot dot]P distances range from 2.22 to 3.27 A.     

Mechanism of anti-inflammatory action of liquorice extract and glycyrrhizin

The antiradical activity, protective effect against lipid peroxidation of liposomal membrane, and inhibitory effect on whole blood reactive oxygen species (ROS) liberation of Glycyrrhiza glabra crude extract and glycyrrhizin, its major compound, were assessed. The liquorice extract showed significant activity in all the three assay systems used in a dose dependent manner. It displayed remarkable reactivity with free stable 1,1'-diphenyl-2-picrylhydrazyl (DPPH) radical, inhibitory efficacy in peroxidatively damaged unilamellar dioleoyl phosphatidylcholine (DOPC) liposomes, and inhibition of ROS chemiluminescence, generated by whole blood, induced by both receptor-bypassing stimuli (PMA) and receptor operating stimuli (Opz) in the ranking order of stimuli PMA> Opz. These activities may be attributed to phenolic antioxidants involving isoflavan derivatives, coumarins and chalcones. Nonetheless, triterpene saponin glycyrrhizin exhibited no efficacy in the system of DPPH reaction and peroxidation of liposomal membrane, and negligible inhibition of chemiluminescence generated by inflammatory cells. These results indicate that the mechanism of anti-inflammatory effect of glycyrrhizin most probably does not involve ROS and this major constituent is not responsible for the inhibition effects of liquorice extract on neutrophil functions.