Three-phase liquid-phase microextraction of weakly basic drugs from whole blood

The behaviour of weak basic analytes in liquid-phase microextraction (LPME) and the optimisation of parameters in whole blood are described. Benzodiazepines and non-benzodiazepine drugs were chosen as model substances. Liquid-phase microextraction based on disposable polypropylene hollow fibres was used in the three-phase extraction of five weak bases from whole blood. The sample work up with the liquid-phase microextraction technique can be impeded by low recovery due to incomplete trapping in the acceptor phase of weakly basic drugs and the complexity of the whole blood matrix. Different parameters related to this problem were experimentally studied. Additionally the stability of the analytes was examined because of low pH in the acceptor phase. The investigation resulted in optimised LPME conditions for the extraction of weak bases from whole blood. The parameters limiting the recovery were evaluated.     

Feeding preferences of eastern spruce budworm larvae in two-choice tests with combinations of host-plant extracts

Three extracts were obtained from each of four host plants: sugars/glycosides; amino acids/bases; and organic acids. The four hosts studied were balsam fir, black spruce, red spruce, and white spuce. The effects of recombined host plant extracts on the feeding behaviour of eastern spruce budworm larvae were examined in two-choice tests. Results compare feeding preferences as well as feeding rates between combinations of extracts. The importance of each class of polar compounds is discussed.

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Préférences des larves de la tordeuse des bourgeons de l'épinette envers extraits combinés de leurs plantes-hôtes

Résumé Trois extraits ont été obtenus de chacune de quatre plantes-hôtes: sucres/glycosides; acides aminées/bases organiques; acides organiques. Les quatre plantes-hôtes étudiées furent le sapin baumier, et les épinettes blanc, noir, et rouge. Le comportement gustatoire des larves a été étudié en raison de l'effet de combinaisons d'extraits de chaque plantehôte. Les résultats comparent la préférence des larves ainsi que leur consommation totale envers ces extraits.

     

The inhibitory effects of phenolic Mannich bases on carbonic anhydrase I and II isoenzymes

Phenolic mono Mannich bases [2-[4-hydroxy-3-(aminomethyl)benzylidene]-2,3-dihydro-1H-inden-1-one (8–15)] and bis Mannich bases [2-[4-hydroxy-3,5-bis(aminomethyl)benzylidene]-2, 3-dihydro-1H-inden-1-one (2–7)] were synthesized starting from 2-(4-hydroxybenzylidene)-2, 3-dihydro-inden-1-one (1). This study was designed in order to investigate the carbonic anhydrase (CA, EC 4.2.1.1) inhibitory properties of a library of compounds incorporating the phenol functional group. All prepared compounds showed a low inhibition percentages on both human (h) isoforms hCA I and hCA II compared to the reference sulfonamide acetazolamide. Mannich bases 2–15 had lower inhibition percentages than the compound 1 on hCA I and hCA II, except compound 14, which is a Mannich base derivative of dipropylamine, which had a similar inhibitory power as compound 1 on hCA II. All compounds synthesized 1–15 were 1.3–1.9 times more effective on hCA II comparing with the effectivenes of the compounds on hCA I.     

Effects of deforestation and cultivation on soil CEC and contents of exchangeable bases: A case study in Simlipal National Park,India

Deforestation in the tropics seems to be a serious problem probably because of the reduction in soil CEC and the consequent losses of nutrients from the soils. Here, changes in these parameters as influenced by deforestation as well as vegetative cover were studied; statistical methods were applied to interpret the results. Cultivation causes a significant reduction in CEC, total content of the exchangeable bases and exchangeable Ca2+ and Mg2+ levels compared to the adjoining unmanaged forest land. Levels of exchangeable K⁺ and Na⁺, however, do not change significantly. Evergreen forest soils have the highest levels of CEC, total exchangeable bases, exchangeable Ca²⁺ and K⁺. Deciduous forest, grassland and cultivated soils have statistically similar contents of exchangeable Ca²⁺, Mg²⁺, K⁺ and Na⁺. Exchangeable Mg²⁺, however, is not affected by vegetative cover. Soil CEC shows fairly good correlation with the organic carbon content only in evergreen forest soils. In others, organic carbon apparently does not influence CEC significantly. All soils show excellent correlation between their CEC and total exchangeable bases. It is concluded that for regeneration of weathered tropical soils, an evergreen cover provides the most effective means; deciduous vegetation or grass cover do not seem promising.     

Antibacterial and antifungal metal based triazole Schiff bases

A new series of four biologically active triazole derived Schiff base ligands (L¹–L⁴) and their cobalt(II), nickel(II), copper(II) and zinc(II) complexes (1–16) have been synthesized and characterized. The ligands were prepared by the condensation reaction of 3-amino-5-methylthio-1H-1,2,4-triazole with chloro-, bromo- and nitro-substituted 2-hydroxybenzaldehyde in an equimolar ratio. The antibacterial and antifungal bioactivity data showed the metal(II) complexes to be more potent antibacterial and antifungal than the parent Schiff bases against one or more bacterial and fungal species.     

Chemical biology on the genome

In this article I discuss studies towards understanding the structure and function of DNA in the context of genomes from the perspective of a chemist. The first area I describe concerns the studies that led to the invention and subsequent development of a method for sequencing DNA on a genome scale at high speed and low cost, now known as Solexa/Illumina sequencing. The second theme will feature the four-stranded DNA structure known as a G-quadruplex with a focus on its fundamental properties, its presence in cellular genomic DNA and the prospects for targeting such a structure in cels with small molecules. The final topic for discussion is naturally occurring chemically modified DNA bases with an emphasis on chemistry for decoding (or sequencing) such modifications in genomic DNA. The genome is a fruitful topic to be further elucidated by the creation and application of chemical approaches.     

Synthesis and SAR studies of potent H+/K+-ATPase inhibitors of quinazolinone-Schiff’s base analogues

A series of quinazolinone derived Schiff base derivatives 7–36 were synthesized and characterized by analytical and spectroscopic techniques. The synthesized analogues were screened for their in vitro H⁺/K⁺-ATPase inhibition. Most of the compounds showed excellent activity, compared to that of omeprazole, a reference drug. In particular, hydroxy and methoxy derivatives 13–24 were the most active compounds possessing a significant increase for different substituents on the benzene ring thus, contributing positively to gastric H⁺/K⁺-ATPase inhibition. Preliminary structure-activity relationship revealed that the compounds 13–24 with electron donating moiety (OH, OCH₃) were found to be excellent activity and compounds 9–12 and 25–36 with electron withdrawing moiety (Cl, F, NO₂ and Br) were found to be least antiulcer agents.     

Evidence for two distinct pyruvate kinase genes in Escherichia coli K-12

A strain of Escherichia coli K-12 defective in pyruvate kinase F has been produced. The existence of this mutant, in conjunction with earlier results, strongly suggests that the two pyruvate kinases in this bacterium are distinct forms and not interconvertible. Either form of pyruvate kinase appeared to be equally effective in the glycolytic conversion of phosphoenolpyruvate to pyruvate. Genes specifying pyruvate kinase A and pyruvate kinase F were present on the small F-prime F506 and the locus for pyruvate kinase F was found to be at minute 36.5 on the E. coli genetic map.