Low Molecular Weight Compounds (low + molecular_weight_compound)

Distribution by Scientific Domains

Selected Abstracts

JS-K, a novel non-ionic diazeniumdiolate derivative, inhibits Hep 3B hepatoma cell growth and induces c-Jun phosphorylation via multiple MAP kinase pathways

Zhenggang Ren
JS-K, a non-ionic diazeniumdiolate derivative, is capable of arylating nucleophiles and spontaneously generating nitric oxide (NO) at physiological pH. This recently synthesized low molecular weight compound is shown here to be an inhibitor of cell growth with concomitant activation of mitogen-activated protein kinase (MAPK) members ERK, JNK, and p38 and their downstream effectors c-Jun and AP-1. Inhibitors of these MAPK pathways abrogated the growth inhibitory actions of JS-K. In addition to the well-described actions of JNK as a kinase for c-Jun, we show that c-Jun is also an ERK target. Furthermore, JS-K generated NO in culture and NO inhibitors antagonized both MAPK induction and the growth inhibitory effects of JS-K. These results suggest two possible mechanisms for the mediation of JS-K growth inhibitory actions, namely NO-induction of MAPK pathway constituents as well as possible arylation reactions. The data support the idea that prolonged MAPK activation by JS-K action is important in mediating its growth-inhibitory actions. JS-K thus represents a promising platform for novel growth inhibitory analog synthesis. J. Cell. Physiol. 197: 426,434, 2003© 2003 Wiley-Liss, Inc. [source]

DOC Release from Alder Leaves and Catkins during Decomposition in a Small Lowland Stream

árka Axmanová
Abstract Alder leaves and catkins were placed in a small stream, then retrieved in weekly intervals, and rates of release of dissolved organic carbon (DOC) and substantial DOC characteristics were determined. Decomposition rates of leaves and catkins were 0.026 d,1 and 0.011 d,1 on the streambed, and 0.017 d,1 and 0.009 d,1 in the sediments, respectively, during 5 weeks of decomposition. The rate of DOC release from leaves declined from 18.0% d,1 to 0.7% d,1, and had a higher proportion of low molecular weight compounds, more saturated and contained larger humic molecules than DOC from catkins, which rate of release declined from 10.6% d,1 to 0.1% d,1. In initial stages of the decomposition, leaf material produced more biodegradable DOC (BDOC) than catkins. During the period of low leaf litter input, DOC released from catkins can become an important instream source of labile DOC. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Removal of organic contaminants in paper pulp effluents by AOPs: an economic study

Montserrat Pérez
Abstract The degradation of the organic content of a bleaching Kraft mill effluent was carried out using Advanced Oxidation Processes (AOPs). The study was focused on the identification of the AOP, or combination of AOPs, that showed the highest efficiency together with the lowest cost. Direct UV photolysis (UV), TiO2 assisted-photocatalysis (TiO2/UV), Fenton, Fenton-like, and photo-Fenton reactions (Fe(II)/H2O/UV), UV-assisted ozonation (O3/UV) and addition of Fe2+ and/or H2O2 to the TiO2/UV and the O3/UV systems, were used for the degradation of a conventional cellulose bleaching effluent. The effluent was characterized by the general parameters TOC, COD and color, and analyzed for chlorinated low molecular weight compounds using GC,MS. The costs of the systems per unit of TOC reduction were compared. Fenton, Fenton-like and photo-Fenton reactions achieved better levels of TOC degradation than photocatalysis and with lower cost's than photocatalytic treatments. Ozonation is an effective but rather expensive process. The use of UVA light, however, increased the effectiveness of ozonation with a significant decrease (>25%) in the operational cost. © 2002 Society of Chemical Industry [source]

Highly cross-linked polymeric capillary monoliths for the separation of low, medium, and high molecular weight analytes

Said H. Lubbad
Abstract Highly rigid capillary monoliths with low swelling propensity were prepared within the confines of 200 ,m ID fused silica capillaries via thermally induced free radical polymerization of tetrakis(4-vinylbenzyl)silane (TVBS) in the presence of 1-dodecanol and toluene. ,,,,-Azobisisobutyronitrile (AIBN) was used as initiator. The resulting monoliths were optimized for the separation of low, medium, and high molecular weight analytes. The microstructure and porosity of the monoliths prepared were studied by SEM and inverse size-exclusion chromatography (ISEC). The porosity of the monolithic supports was tuned by varying the amount of initiator (i. e. AIBN) between 0.5 and 2 wt%. All monoliths were tested for a series of low molecular weight compounds including alkylbenzenes, amines, carboxylic acids, phenols, carbonyl compounds, and ,-blockers, as well as for the separation of medium molecular weight analytes such as peptides and high-molecular weight analytes such as proteins. Due to the microporous structure, the novel monoliths displayed high efficiency and performance particularly in the separation of low molecular weight analytes. Relevant chromatographic parameters including permeability, swelling propensity, and height equivalents to theoretical plates were determined. [source]

Anticandidal low molecular compounds from higher plants with special reference to compounds from essential oils,

A. Pauli
Abstract The most active low molecular weight compounds from higher plants against Candida species are compiled from a database of antimicrobials (Amicbase) to find out new hints on their mechanism of action. The selected compounds possess strong inhibitory activities in vitro against Candida species either in the agar diffusion test, bioautography, agar dilution test, serial dilution test, or activity in the vapour phase. The test conditions are listed thoroughly and aspects of the different methods and recent developments in the testing of anticandidal drugs are discussed. The anticandidal spectra of drugs, antiseptics, and disinfectants licensed on the major markets are given for comparision of activities with compounds from natural sources. So far known mechanisms of action are described and some new structure,activity relationships are deduced from relationships between biological activities and chemical and physical parameters. Main specific targets of natural anticandidals are the ergosterol pathway, respiratory chain, and chitin biosynthesis. © 2005 Wiley Periodicals, Inc. Med Res Rev [source]

Cross-linked agarose for separation of low molecular weight natural products in hydrophilic interaction liquid chromatography

Tianwei Tan
Abstract Following its market introduction in 1982, the cross-linked 12% agarose gel media Superose 12 has become widely known as a tool for size exclusion chromatography of proteins and other biological macromolecules. In this review it is shown that, when appropriate mobile phases are used, Superose possesses adsorption properties similar to that of traditional media for hydrophilic interaction liquid chromatography (HILIC). This is illustrated by the separation and purification of low molecular weight compounds such as polyphenols including active components of traditional Chinese medicinal herbs and green tea. Structural features of the cross-linked agarose that likely cause the observed adsorption effects are discussed aswell. These are identified as being primarily ether bonds acting as strong hydrogen bond acceptors as well as hydrophobic residues originating from the cross-linking reagents. [source]

Everything depends on everything else

J. Davies
Abstract In physics the concept of entanglement is well established and it has become increasingly apparent that all levels of biological organization (communities, organisms, cells, metabolism) consist of mosaics of interactive networks. There is a universe of bioactive microbial chemicals that have so far only been considered for their therapeutic applications; for example, the environmental roles of antibiotics have been little investigated. At sub-inhibitory concentrations, so-called antibiotics have been shown to modulate bacterial functions in subtle ways; they behave more like signals than toxins. It is proposed that networks of microbial cell signalling are primarily based on the interactions of low molecular weight compounds with macromolecular receptors; studies of the nature of these signals will reveal important information on the functions of microbial communities. [source]