Linear and networked polymers formed by the near simultaneous occurrence of etherification and esterification under mild reaction conditions

Despite the large difference in their nucleophilicity, phenoxide and carboxylate anions take part nearly simultaneously in the aliphatic nucleophilic substitution reaction with 1,4‐dibromo‐2‐butene. This leads to the formation of ether (? O? ) and ester (? COO? ) linkages simultaneously under mild reaction conditions when hydroxyl benzoic acids are employed as nucleophiles. The process yields a new class of polymer broadly classified as unsaturated poly(ether ester) which are potentially functionalizable. This methodology has also been extended for preparing networked polymers by making use of 3,5‐dihydroxybenzoic acid as A₃ type monomer. Copyright © 2011 Society of Chemical Industry     

BDD anodic oxidation as tertiary wastewater treatment for the removal of emerging micro‐pollutants,pathogens and organic matter

This work reports for the first time the removal of 17α‐ethynylestradiol (EE2), a synthetic estrogen hormone, from secondary treated effluents by electrochemical oxidation. Experiments were conducted in a single compartment reactor comprising a boron‐doped diamond (BDD) anode and a zirconium cathode. EE2, in the range 100–800 µg L^?1, was spiked in the post‐chlorination effluent of a municipal treatment plant and oxidized at 0.9–2.6 mA cm^?2 current density. Complete degradation of 100 µg L^?1 EE2 was achieved in 7 min at 2.1 mA cm^?2 and inherent conditions, while the addition of 0.1 mol L^?1 NaCl achieved removal in just a few seconds. The process was then tested in the pre‐chlorination effluent at 2.1 mA cm^?2 and inherent conditions; complete E. coli killing and EE2 removal occurred in just 1.5 and 3.5 min, respectively, while overall estrogenicity (assessed by the YES assay) and residual organic matter (in terms of chemical oxygen demand (COD)) decreased by 50% and 85% after 30 min, respectively. These results clearly show the potential of BBD electrochemical oxidation to serve as an efficient tertiary wastewater treatment. Copyright © 2011 Society of Chemical Industry     

Mutation of herpesvirus thymidine kinase to generate ganciclovir-specific kinases for use in cancer gene therapies

Understanding the functional and mechanistic properties of themulti-substrate herpes simplex virus type-1 thymidine kinase(HSV-1 TK) remains critical to defining its role as a majorpharmacological target in herpesvirus and gene therapies forcancer. An inherent limitation of the activity of HSV-TK isthe >70-fold difference in the K_ms for phosphorylation ofthymidine over the pro-drug ganciclovir (GCV). To engineer anHSV-1 TK isoform that is specific for GCV as the preferred substrate,16 site-specific mutants were generated. The mutations wereconcentrated at conserved residues involved in nucleoside basebinding, Gln125 and near sites 3 and 4 involved in catalysisand substrate binding. The substrate preferences of each mutantenzyme were compared with wild-type HSV-1 TK. One mutant, termedQ7530 TK, had a lower K_m for GCV than thymidine. Expressionof the Q7530 TK in tumor cells indicated comparable metabolismto and improved sensitivity to GCV over wild-type HSV-1 TK,with minimal thymidine phosphorylation activity. A molecularmodeling simulation of the different HSV-1 TK active-sites wasdone for GCV and thymidine binding. It was concluded that mutationsat Gln125 and near site 4, especially at Ala168, were responsiblefor loss of deoxypyrimidine substrate binding.     

Chitosan-based fiber-sponge materials as a promising tool for microalgae harvesting from Lake Baikal

Mass eutrophication of microalgae and cyanobacteria is observed in Lake Baikal in the past decade. In this paper, the concept of replaceable adsorption filter material based on chitosan flocculant filler and chlorinated polyvinyl chloride polymer nonwoven material are proposed. Functional and mechanical properties and morphology of the material are investigated depending on a packing density and a degree of chitosan filling. The introduction of 45% chitosan increases the Young's modulus up to 10 times, and it makes the material more rigid in 2.8 times. The high efficiency of sorption and growth inhibition of cumulative biomass culture was shown. The biomass source is taken from the coast of Barguzinsky Bay of Lake Baikal. Dominant species is microalgae of Scenedesmus genus.     

Structural Consequences of the 1,2,3-Triazole as an Amide Bioisostere in Analogues of the Cystic Fibrosis Drugs VX-809 and VX-770

Although the 1,2,3-triazole is a commonly used amide bioisostere in medicinal chemistry, the structural implications of this replacement have not been fully studied. Employing X-ray crystallography and computational studies, we report the spatial and electronic consequences of replacing an amide with the triazole in analogues of cystic fibrosis drugs in the VX-770 and VX-809 series. Crystallographic analyses quantify subtle differences in the relative positions and conformational preferences of the R¹ and R² substituents attached to the amide and triazole bioisosteres. Computational studies derived from the X-ray data highlight the improved hydrogen bonding donor and acceptor capabilities of the amide in comparison to the triazole. This analysis of the spatial and electronic differences between the amide and 1,2,3-triazole will inform medicinal chemists as they consider using the triazole as an amide bioisostere.     

<Superscript>1</Superscript>H-NMR Spectroscopy as a New Tool in the Assessment of the Oxidative State in Edible Oils

Within the course of lipid peroxidation, hydroperoxides are formed as primary products. They can be used as analytical markers to assess the deterioration status of oils and fats. Here a new ¹H-NMR assay to determine the hydroperoxide amount in edible oils is presented. We were able to show that the analytical performance of the method is similar to that of the commonly used peroxide value (PV) according to Wheeler. A total of 290 edible oil samples were analyzed using both methods. For some oil varieties considerable discrepancies were found between the results obtained. In the case of black seed and olive oil, two substances could be identified that cause positive (black seed oil) and negative (olive oils) deviations from the theoretical PV expected from the NMR values.     

Activation of the glmS Ribozyme Confers Bacterial Growth Inhibition

The ever‐growing number of pathogenic bacteria resistant to treatment with antibiotics call for the development of novel compounds with as‐yet unexplored modes of action. Here, we demonstrate the in vivo antibacterial activity of carba‐α‐d ‐glucosamine (CGlcN). In this mode of action study, we provide evidence that CGlcN‐mediated growth inhibition is due to glmS ribozyme activation, and we demonstrate that CGlcN hijacks an endogenous activation pathway, hence utilizing a prodrug mechanism. This is the first report describing antibacterial activity mediated by activating the self‐cleaving properties of a ribozyme. Our results open the path towards a compound class with an entirely novel and distinct molecular mechanism.     

Peptide Paratope Mimics of the Broadly Neutralizing HIV‐1 Antibody b12

The broadly neutralizing HIV‐1 antibody b12 recognizes the CD4 binding site of the HIV‐1 envelope glycoprotein gp120 and efficiently neutralizes HIV‐1 infections in vitro and in vivo. Based on the 3D structure of a b12 ? gp120 complex, we have designed an assembled peptide (b12‐M) that presents the parts of the three heavy‐chain complementarity‐determining regions (CDRs) of b12, which contain the contact sites of the antibody for gp120. This b12‐mimetic peptide, as well as a truncated peptide presenting only two of the three heavy‐chain CDRs of b12, were shown to recognize gp120 in a similar manner to b12, as well as to inhibit HIV‐1 infection, demonstrating functional mimicry of b12 by the paratope mimetic peptides.     

Host Suitability Affects Odor Association in <Emphasis Type="Italic">Cotesia marginiventris</Emphasis>: Implications in Generalist Parasitoid Host-Finding

Insect herbivores often induce plant volatile compounds that can attract natural enemies. Cotesia marginiventris (Hymenoptera: Braconidae) is a generalist parasitoid wasp of noctuid caterpillars and is highly attracted to Spodoptera exigua-induced plant volatiles. The plasticity of C. marginiventris associative learning to volatile blends of various stimuli, such as host presence, also has been shown, but little is known about how this generalist parasitoid distinguishes between host species of varying suitability. Spodoptera exigua is an excellent host that yields high parasitoid emergence, while Trichoplusia ni serves as a sub-optimal host species due to high pre-imaginal wasp mortality. We have found that S. exigua and T. ni induce different volatile blends while feeding on cotton. Here, wind tunnel flight assays were used to determine the importance of differentially induced volatiles in host-finding by C. marginiventris. We found that, while this generalist parasitoid wasp can distinguish between the two discrete volatile blends when presented concurrently, a positive oviposition experience on the preferred host species (S. exigua) is more important than host-specific volatile cues in eliciting flight behavior towards plants damaged by either host species. Furthermore, wasps with oviposition experience on both host species did not exhibit a deterioration in positive flight behavior, suggesting that oviposition in the sub-optimal host species (T. ni) does not cause aversive odor association.     

Do Bumble Bee, <Emphasis Type="Italic">Bombus impatiens</Emphasis>, Queens Signal their Reproductive and Mating Status to their Workers?

Reproduction in social insect societies reflects a delicate balance between cooperation and conflict over offspring production, and worker reproduction is widespread even in species showing strong reproductive skew in favor of the queen. To navigate these conflicts, workers are predicted to develop the means to estimate the queen’s fecundity - potentially through behavioral and/or chemical cues - and to adjust their reproduction to maximize their fitness. Here, we introduced bumble bee, Bombus impatiens, workers to queens of different mating and reproductive status and examined worker reproduction and expression levels of two genes which were previously shown to be sensitive to the presence of the queen, vitellogenin and Krüppel-homolog 1. We further explored whether the queen’s chemical secretion alone is sufficient to regulate worker reproduction, aggression and gene expression. We found that worker ovary activation was inhibited only in the presence of egg-laying queens, regardless of their mating status. Workers reared in the presence of newly-mated queens showed intermediate vitellogenin expression levels relative to workers reared with mated egg-laying and virgin queens. However, none of the whole-body chemical extracts of any of the queen treatment groups affected ovary activation, aggressive behavior, or gene expression in workers. Our findings indicate that only the presence of a freely-behaving, egg-laying queen can fully inhibit worker reproduction. It remains to be determined if workers detect differences in queen mating status and fecundity through differences in the queens’ behavior alone or through the queen’s behavior in concert with fertility signals.