982 resultados para 2,4-dichlorophenol


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Coumarins are extensively studied anticoagulants that exert additional effects such as anticancerogenic and even anti-inflammatory. In order to find new drugs with anticancer activities, we report here the synthesis and the structural analysis of new coumarin derivatives which combine the coumarin core and five member heterocycles in hydrazinylidene-chroman-2,4-diones. The derivatives were prepared by derivatization of the appropriate heterocyclic amines which were used as electrophiles to attack the coumarin ring. The structures were characterized by spectroscopic techniques including IR, NMR, 2D-NMR and MS. These derivatives were further characterized especially in terms of a potential cytotoxic and apoptogenic effect in several cancer cell lines including the breast and prostate cancer cell lines MCF-7, MDA-MB-231, PC-3, LNCaP, and the monocytic leukemia cell line U937. Cell viability was determined after 48 h and 72 h of treatment with the novel compounds by MTT assay and the 50% inhibitory concentrations (EC50 values) were determined. Out of the 8 novel compounds screened for reduced cell viability, 4c, 4d and 4e were found to be the most promising and effective ones having EC50 values that were several fold reduced when compared to the reference substance 4-hydroxycoumarin. However, the effects were cancer cell line dependent. The breast cancer MDA-MB-231 cells, the prostate cancer LNCaP cells, and U937 cells were most sensitive, MCF-7 cells were less sensitive, and PC-3 cells were more resistant. Reduced cell viability was accompanied by increased apoptosis as shown by PARP-1 cleavage and reduced activity of the survival protein kinase Akt. In summary, this study has identified three novel coumarin derivatives that in comparison to 4-hydroxycoumarin have a higher efficiency to reduce cancer cell viability and trigger apoptosis and therefore may represent interesting novel drug candidates

Relevância:

100.00% 100.00%

Publicador:

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Plants differ greatly in their susceptibility to insect herbivory, suggesting both local adaptation and resistance tradeoffs. We used maize (Zea mays) recombinant inbred lines to map a quantitative trait locus (QTL) for the maize leaf aphid (Rhopalosiphum maidis) susceptibility to maize Chromosome 1. Phytochemical analysis revealed that the same locus was also associated with high levels of 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside (HDMBOA-Glc) and low levels of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one glucoside (DIMBOA-Glc). In vitro enzyme assays with candidate genes from the region of the QTL identified three O-methyltransferases (Bx10a-c) that convert DIMBOA-Glc to HDMBOA-Glc. Variation in HDMBOA-Glc production was attributed to a natural CACTA family transposon insertion that inactivates Bx10c in maize lines with low HDMBOA-Glc accumulation. When tested with a population of 26 diverse maize inbred lines, R. maidis produced more progeny on those with high HDMBOA-Glc and low DIMBOA-Glc. Although HDMBOA-Glc was more toxic to R. maidis than DIMBOA-Glc in vitro, BX10c activity and the resulting decline of DIMBOA-Glc upon methylation to HDMBOA-Glc were associated with reduced callose deposition as an aphid defense response in vivo. Thus, a natural transposon insertion appears to mediate an ecologically relevant trade-off between the direct toxicity and defense-inducing properties of maize benzoxazinoids.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Synthetic chemical elicitors of plant defense have been touted as a powerful means for sustainable crop protection. Yet, they have never been successfully applied to control insect pests in the field. We developed a high-throughput chemical genetics screening system based on a herbivore-induced linalool synthase promoter fused to a β-glucuronidase (GUS) reporter construct to test synthetic compounds for their potential to induce rice defenses. We identified 2,4-dichlorophenoxyacetic acid (2,4-D), an auxin homolog and widely used herbicide in monocotyledonous crops, as a potent elicitor of rice defenses. Low doses of 2,4-D induced a strong defensive reaction upstream of the jasmonic acid and ethylene pathways, resulting in a marked increase in trypsin proteinase inhibitor activity and volatile production. Induced plants were more resistant to the striped stem borer Chilo suppressalis, but became highly attractive to the brown planthopper Nilaparvata lugens and its main egg parasitoid Anagrus nilaparvatae. In a field experiment, 2,4-D application turned rice plants into living traps for N. lugens by attracting parasitoids. • Our findings demonstrate the potential of auxin homologs as defensive signals and show the potential of the herbicide to turn rice into a selective catch crop for an economically important pest.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The title compound, C21H33N3O3, is a tri-substituted cyclo­hex­yloxy triazine. In the crystal, the triazine rings form (C3i-PU) Piedfort units. The inter-centroid distance of the [pi]-[pi] inter­action involving the triazine rings is 3.3914 (10) Å. In the crystal, mol­ecules are linked by C-H...O hydrogen bonds, forming ribbons propagating along [1-10]. There are also weak C-H...N and C-H...O contacts present, linking inversion-related ribbons, forming a three-dimensional structure.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A bitopic ligand, 4-(3,5-dimethylpyrazol-4-yl)-1,2,4-triazole (Hpz-tr) (1), containing two different heterocyclic moieties was employed for the design of copper(II)–molybdate solids under hydrothermal conditions. In the multicomponent CuII/Hpz-tr/MoVI system, a diverse set of coordination hybrids, [Cu(Hpz-tr)2SO4]·3H2O (2), [Cu(Hpz-tr)Mo3O10] (3), [Cu4(OH)4(Hpz-tr)4Mo8O26]·6H2O (4), [Cu(Hpz-tr)2Mo4O13] (5), and [Mo2O6(Hpz-tr)]·H2O (6), was prepared and characterized. A systematic investigation of these systems in the form of a ternary crystallization diagram approach was utilized to show the influence of the molar ratios of starting reagents, the metal (CuII and MoVI) sources, the temperature, etc., on the reaction products outcome. Complexes 2–4 dominate throughout a wide crystallization range of the composition triangle, while the other two compounds 5 and 6 crystallize as minor phases in a narrow concentration range. In the crystal structures of 2–6, the organic ligand behaves as a short [N–N]-triazole linker between metal centers Cu···Cu in 2–4, Cu···Mo in 5, and Mo···Mo in 6, while the pyrazolyl function remains uncoordinated. This is the reason for the exceptional formation of low-dimensional coordination motifs: 1D for 2, 4, and 6 and 2D for 3 and 5. In all cases, the pyrazolyl group is involved in H bonding (H-donor/H-acceptor) and is responsible for π–π stacking, thus connecting the chain and layer structures in more complicated H-bonding architectures. These compounds possess moderate thermal stability up to 250–300 °C. The magnetic measurements were performed for 2–4, revealing in all three cases antiferromagnetic exchange interactions between neighboring CuII centers and long-range order with a net moment below Tc of 13 K for compound 4.

Relevância:

100.00% 100.00%

Publicador:

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Rhodobacter sphaeroides 2.4.1 is a Gram negative facultative photoheterotrophic bacterium that has been shown to have an N-acyl homoserine lactone-based quorum sensing system called cer for c&barbelow;ommunity e&barbelow;scape r&barbelow;esponse. The cer ORFs are cerR, the transcriptional regulator, cerI, the autoinducer synthase and cerA , whose function is unknown. The autoinducer molecule, 7,8- cis-N-(tetradecenoyl) homoserine lactone, has been characterized. The objective of this study was to identify an environmental stimulus that influences the regulation of cerRAI and, to characterize transcription of the cer operon. ^ A cerR::lacZ transcriptional fusion was made and β-Galactosidase assays were performed in R. sphaeroides 2.4.1 strains, wild type, AP3 (CerI−) and AP4 (CerR−). The cerR::lacZ β-Galactosidase assays were used as an initial survey of the mode of regulation of the Cer system. A cerA::lacZ translational fusion was created and was used to show that cerA can be translated. The presence of 7,8-cis-N-(tetradecenoyl) homoserine lactone was detected from R. sphaeroides strains wild type and AP4 (CerR−) using a lasR::lacZ translational fusion autoinducer bioassay. The cerR::lacZ transcriptional fusion in R. sphaeroides 2.4.1 wild type was tested under different environmental stimuli, such as various carbon sources, oxygen tensions, light intensities and culture media to determine if they influence transcription of the cer ORFs. Although lacZ assay data implicated high light intensity at 100 W/m2 to stimulate cer transcription, quantitative Northern RNA data of the cerR transcript showed that low light intensity at 3 W/m2 is at least one environmental stimulus that induces cer transcription. This finding was supported by DNA microarray analysis. Northern analysis of the cerRAI transcript provided evidence that the cer ORFs are co-transcribed, and that the cer operon contains two additional genes. Bioinformatics was used to identify genes that may be regulated by the Cer system by identifying putative lux box homologue sequences in the presumed promoter region of these genes. Genes that were identified were fliQ, celB and calsymin, all implicated in interacting with plants. Primer extension was used to help localize cis-elements in the promoter region. The cerR::lacZ transcriptional fusion was monitored in a subset of different global DNA binding transcriptional regulator mutant strains of R. sphaeroides 2.4.1. Those regulators involved in maintaining an anaerobic photosynthetic lifestyle appeared to have an effect. Collectively, the data imply that R. sphaeroides 2.4.1 activates the Cer system when grown anaerobic photosynthetically at low light intensity, 3 W/m2, and it may be involved in an interaction with plants. ^

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Vorlesung: "Einführung in die Philosophie der Gegenwart", SS 1926, Typoskript mit eigenhändigen Korrekturen, 185 Blatt; Vortrag: "Über Sinn und Grenze einer soziologischen Behandlungen der Philosophie", 1928 (?), Typsokript mit eigenhändigen Korrekturen, 10 Blatt (GS 11, S. 209-220); Vortrag, gehalten zu Beginn der Vorlesung: "Max Scheler (1874-1928)", "Einführung in die Geschichtsphilosophie", SS 1928, Typoskript mit eigenhändigen Korrekturen, 13 Blatt (GS 11, 145-157); Vortrag: "Über Kantische und moderne Ethik" Typsokript mit eigenhändigen Korrekturen, 6 Blatt (GS 11, S. 138-144);

Relevância:

100.00% 100.00%

Publicador:

Resumo:

"Antisemitism and American Labor. A Research Project of the Institut of Social Research", Januar 1944 (revised June 1944); a) als Typoskript vervielfältigt, 14 Blatt; b) Typoskript, 14 Blatt; Institut of Social Research: "Project an Antisemitism and American Labor", Januar 1944; a) Typoskript, 18 Blatt; b) Typoskript, mit handschriftlichen Korrekturen, 17 Blatt, c) Teilstück, Typoskript mit handschriftlichen Korrekturen, 1 Blatt; d) Teilstück, Typoskript mit handschriftlichen Korrekturen, 1 Blatt; e) Teilstück, Typoskript mit handschriftlichen Korrekturen, 5 Blatt; f) Teilstück, Typoskript mit handschriftlichen Korrekturen, 4 Blatt; "Project on Antisemitism an American Labor", Dezember 1943; a) Typoskript mit handschriftlichen Korrekturen, 18 Blatt; b) Typoskript mit handschriftlichen Korrekturen von Theodor W. Adorno, 17 Blatt; c) Typoskript mit handschriftlichen Korrekturen, 12 Blatt; Memoranden 1941-1949; Adorno, Theodor W. to Löwenthal, Leo: "Supplement to the Memorandum of 7/28/49 by Pollock, Friedrich re Labor Study", 18.09.1949. Typoskript, 6 Blatt; Adorno, Theodor W.: "Memorandum re: Antisemitism among American Labor, as edited by the Bureau of Applied Social Research", 19.07.1949. Typoskript, 8 Blatt; "Expenses for Project: Antisemitism among Labor, june 1, 1944- May 31,1945". Typoskript, 1 Blatt; Institut of Social Research: "Interim Memorandum on Progress of Project on Antisemitism within Labor", 04.09.1944. Typoskript, 11 Blatt; Institut of Social Research: "Re: Project on Labor and Antisemitism. Difficulties to be expected", 21.03.1944. Typoskript, 3 Blatt; "Re: Project on Labor and Antisemitism. Plants to be Contacted", 21.03.1944. Typoskript, 2 Blatt; "Some Remarks to Dr. Gelle's Report 'Der deutsche Progrom, a, 10. November 1938'", 11.03.1944. Typoskript, 12 Blatt; Adorno, Theodor W. ?: "Adress to ameeting of the Jewish Labor Committee, January 20th, 1944, los Angeles". Typoskript mit eigenhändigen Ergänzungen, 2 Blatt; Pollock, Friedrich: "Re: Sherman", 31.12.1943, 1 Blatt; "Memorandum re: Jewish Labor Committee", 23.12.1943. Typoskript mit handschriftlichen Korrekturen, 2 Blatt; "Tentative Budget for a Trial Survey on Antisemitism among American Labor", 23.12.1943. Typoskript, 1 Blatt; "Council for Democracy. Survey on Antisemitism. Hartford, Conn., late 1941". Typoskript, 4 Blatt; "Council for Democracy. Survey on Antisemitism. Terre Haute, Ind.". Typoskript, 2 Blatt; Horkheimer, Max: Eigenhändige Notizen zum Projekt, 3 Blatt; "Some heading lind", handschriftlichen Notizen, 1 Blatt; Institut of Social research: "Instructuins", Fragebogen, als Typoskript vervielfältigt, 3 Blatt; "Instructions for Interviews on Attitudes of Workers and White Collar Workers towards Jews". Als Typoskript vervielfältigt, 1 Blatt; Horkheimer, Max: 1 Briefentwurf an Friedrich Pollock, ohne Ort, ohne Datum, 1 Blatt; Pollock, Friedrich: 3 Briefe an Max Horkheimer, ohne Ort, 1943, 3 Blatt; Sherman, Charles B.: 1 Brief mit Unterschrift an Friedrich Pollock, New York, 23.12.1943; 3 Briefe von Friedrich Pollock, New York, 1943-1944, 5 Blatt;

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We present Plio-Pleistocene records of sediment color, %CaCO3, foraminifer fragmentation, benthic carbon isotopes (d13C) and radiogenic isotopes (Sr, Nd, Pb) of the terrigenous component from IODP Site U1313, a reoccupation of benchmark subtropical North Atlantic Ocean DSDP Site 607. We show that (inter)glacial cycles in sediment color and %CaCO3 pre-date major northern hemisphere glaciation and are unambiguously and consistently correlated to benthic oxygen isotopes back to 3.3 million years ago (Ma) and intermittently so probably back to the Miocene/Pliocene boundary. We show these lithological cycles to be driven by enhanced glacial fluxes of terrigenous material (eolian dust), not carbonate dissolution (the classic interpretation). Our radiogenic isotope data indicate a North American source for this dust (~3.3-2.4 Ma) in keeping with the interpreted source of terrestrial plant wax-derived biomarkers deposited at Site U1313. Yet our data indicate a mid latitude provenance regardless of (inter)glacial state, a finding that is inconsistent with the biomarker-inferred importance of glaciogenic mechanisms of dust production and transport. Moreover, we find that the relation between the biomarker and lithogenic components of dust accumulation is distinctly non-linear. Both records show a jump in glacial rates of accumulation from Marine Isotope Stage, MIS, G6 (2.72 Ma) onwards but the amplitude of this signal is about 3-8 times greater for biomarkers than for dust and particularly extreme during MIS 100 (2.52 Ma). We conclude that North America shifted abruptly to a distinctly more arid glacial regime from MIS G6, but major shifts in glacial North American vegetation biomes and regional wind fields (exacerbated by the growth of a large Laurentide Ice Sheet during MIS 100) likely explain amplification of this signal in the biomarker records. Our findings are consistent with wetter-than-modern reconstructions of North American continental climate under the warm high CO2 conditions of the Early Pliocene but contrast with most model predictions for the response of the hydrological cycle to anthropogenic warming over the coming 50 years (poleward expansion of the subtropical dry zones).