Biocatalytic and semisynthetic optimization of the anti-invasive tobacco (1S,2E,4R,6R,7E,11E)-2,7,11-cembratriene-4,6-diol

Tobacco cembranoids were reported to inhibit tumorigenesis. Biocatalysis of (1S,2E,4R,6R,7E,11E)-2,7,11-cembratriene-4,6-diol (1) using the symbiotic Bacillus sp. NC5, Bacillus sp. NK8, and Bacillus sp. NK7, isolated from the Red Sea sponge Negombata magnifica, afforded two new and four known hydroxylated metabolites 3-8. The use of symbiotic marine bacteria as biocatalysts for bioactive natural product scaffolds is very rare. Cembranoid 1 carbamate analogs 9-11 were prepared by its reaction with corresponding isocyanates. Cembranoid 1 and its bioconversion and carabamate products show anti-invasive activity against the human highly metastatic prostate PC-3M cancer cell line at 10-50 nM doses in Matrigel assay.     

Constitution and quantity of lysis buffer alters outcome of reverse phase protein microarrays

Application of novel technology to clinical samples requires optimization of procedures. Reverse phase protein lysate arrays use femtomolar quantities of tissue lysate from clinical samples with which to profile biochemical events happening in the tumor. We analyzed the effects of different tissue solubilization buffers on frozen ovarian tumor samples in order to identify the system with the best signal intensity dynamic range, reproducibility, tissue solubility, and signal consistency. A modified RIPA-like buffer supplemented with DTT and SDS was deemed optimal.     

Release of intracellular Zn<Superscript>2+</Superscript> in cultured neurons after brief exposure to low concentrations of exogenous nitric oxide

Several studies have shown intracellular Zn²⁺ release and concomitant cell death after prolonged exposure to exogenous NO. In the present study, we investigated whether cortical neurons briefly exposured to exogenous NO would demonstrate similar levels of intracellular Zn²⁺ release and subsequent cell death. Cortical neurons were loaded with the Zn²⁺ selective fluorophore FluoZin-3 and treated with various concentrations of the NO generator, spermine NONOate. Fluorescence microscopy was used to detect and quantify intracellular Zn²⁺ levels. Concomitant EDTA perfusion was used to eliminate potential effects of extracellular Zn²⁺. Neurons were perfused with the heavy metal chelator TPEN to selectively eliminate Zn²⁺ induced fluorescence changes. A significant increase of intracellular fluorescence was detected during a 5 min perfusion with spermine NONOate. The increase in intracellular Zn²⁺ release appeared to peak at 1 μM spermine NONOate (123.8 ± 28.5%, increase above control n = 20, P < 0.001). Further increases in spermine NONOate levels as high as 1 mM failed to further increase detectable intracellular Zn²⁺ levels. The NO scavenger hemoglobin blocked the effects of spermine NONOate and the inactive analog of the spermine NONOate, spermine, was without effect. No evidence of cell death induced by any of the brief treatments with exogenous NO was observed; only prolonged incubation with much larger amounts of exogenous NO resulted in significant cell death. These data suggest that in vivo release of NO may cause elevations of intracellular Zn²⁺ in cortical neurons. The possibility that release of intracellular Zn²⁺ in response to NO could play a role in intracellular signaling is discussed.     

Analysis of the mitochondrial genome of the Indian darter,Anhinga melanogaster,suggests a species status taxonomic rank

Molecular Biology Reports - Anhinga melanogaster is a carnivorous water bird native to many Asian countries. A. melanogaster is part of the Old World clade of darters. There is currently...     

Synthesis, antimicrobial and antioxidant evaluation of quinolines and bis(indolyl)methanes

An improved and practical synthesis of substituted quinolines and bis(indolyl)methanes was achieved under microwave condition using Zn(OTf)(2) as catalyst. The synthesized compounds have been screened for antimicrobial and antioxidant activities.     

Caged vanilloid ligands for activation of TRPV1 receptors by 1- and 2-photon excitation

Nociceptive neurons in the peripheral nervous system detect noxious stimuli and report the information to the central nervous system. Most nociceptive neurons express the vanilloid receptor, TRPV1, a nonselective cation channel gated by vanilloid ligands such as capsaicin, the pungent essence of chili peppers. Here, we report the synthesis and biological application of two caged vanilloids: biologically inert precursors that, when photolyzed, release bioactive vanilloid ligands. The two caged vanilloids, Nb-VNA and Nv-VNA, are photoreleased with quantum efficiency of 0.13 and 0.041, respectively. Under flash photolysis conditions, photorelease of Nb-VNA and Nv-VNA is 95% complete in approximately 40 micros and approximately 125 micros, respectively. Through 1-photon excitation with ultraviolet light (360 nm), or 2-photon excitation with red light (720 nm), the caged vanilloids can be photoreleased in situ to activate TRPV1 receptors on nociceptive neurons. The consequent increase in intracellular free Ca(2+) concentration ([Ca(2+)](i)) can be visualized by laser-scanning confocal imaging of neurons loaded with the fluorescent Ca(2+) indicator, fluo-3. Stimulation results from TRPV1 receptor activation, because the response is blocked by capsazepine, a selective TRPV1 antagonist. In Ca(2+)-free extracellular medium, photoreleased vanilloid can still elevate [Ca(2+)](i), which suggests that TRPV1 receptors also reside on endomembranes in neurons and can mediate Ca(2+) release from intracellular stores. Notably, whole-cell voltage clamp measurements showed that flash photorelease of vanilloid can activate TRPV1 channels in <4 ms at 22 degrees C. In combination with 1- or 2-photon excitation, caged vanilloids are a powerful tool for probing morphologically distinct structures of nociceptive sensory neurons with high spatial and temporal precision.     

Optimization of labile esters for esterase-assisted accumulation of nitroxides into cells: a model for in vivo EPR imaging

Nitroxide-based electron paramagnetic resonance (EPR) imaging agents are useful quantitative probes of O2 concentration in vivo in real time. Lipophilic, labile alkanoyloxymethyl esters of nitroxides can cross the blood-brain barrier, and after hydrolysis, the corresponding anionic nitroxide is intracellularly entrapped at levels sufficient to permit O2 measurements. The utility of nitroxides as EPR imaging agents depends critically on their ability to accumulate in the brain to high levels. In this study, we systematically investigated the relationship between the structure of the alkanoyl moiety and the ability of the corresponding labile ester to deliver nitroxide intracellularly. We demonstrate, in a cultured cell model, that for nitroxide labile esters with unbranched alkanoyl chains, increasing the chain length improves intracellular loading. Moreover, by studying an isomeric series of labile esters, we conclude that branching of the alkanoyl chain drastically reduces intracellular loading. These structural insights improve our general ability to use labile esters to deliver carboxylates intracellularly, and suggest a strategy for enhancing delivery of nitroxide imaging agents across the blood-brain barrier in a living animal.