Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
Molecules ; 28(19)2023 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-37836767

RESUMO

Cirsium japonicum DC. var. australe Kitam. has been used as an herbal remedy and often involves using the whole plant or roots. However, the bioactivities of different parts of the plant have been far less explored. This study aimed to evaluate the antioxidative ability of methanol extracts from the flowers, leaves, stems, and roots of the Cirsium plant and their possible active components against juglone-induced oxidative stress in the nematode Caenorhabditis elegans. The results showed that the highest dry weight (12.3 g per plant) was observed in leaves, which was followed by stems (8.0 g). The methanol extract yields from the flowers, leaves, and roots were all similar (13.0-13.8%), while the yield from stems was the lowest (8.6%). The analysis of the silymarin contents in the extracts indicated that the flowers, leaves, stems, and roots contained silychristin and taxifolin; however, silydianin was only found in the leaves, stems, and roots. The flower, leaf, and stem extracts, at a concentration of 10 mg/L, significantly reduced juglone-induced oxidative stress in C. elegans, which was potentially due to the presence of silychristin and taxifolin. Overall, C. japonicum DC. var. australe Kitam. contains a significant amount of silymarin and exhibits in vivo antioxidative activity, suggesting that the prospects for the plant in terms of health supplements or as a source of silymarin are promising.


Assuntos
Cirsium , Silimarina , Animais , Caenorhabditis elegans , Flavonoides/farmacologia , Extratos Vegetais/farmacologia , Metanol , Estresse Oxidativo , Antioxidantes/farmacologia
2.
PhytoKeys ; 210: 53-65, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36760411

RESUMO

A new species of Smithia Aiton, S.yehii C.M.Wang, Chih Y.Chang & Y.H.Tseng, sp. nov. from the wetlands of Taiwan is reported in this article. This species was mistakenly identified as S.sensitiva Aiton, but can be distinguished by its pale yellow corolla (vs. vivid yellow), often smaller flowers and shorter style. There is also a color gradient on the adaxial surface of the leaflets between young and mature leaves. Surface sculpture of pollen of S.yehii has significantly larger perforations, and muri are wider than those of S.sensitiva. An identification key to the Smithia taxa of Taiwan and S.sensitiva is presented.

3.
PhytoKeys ; 183: 35-53, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34720629

RESUMO

A new species of Cirsium, C.taiwanense Y.H.Tseng & Chih Y.Chang from central-northern Taiwan is reported in this article. This species is similar to C.hosokawae Kitam. in having a densely cobwebby abaxial leaf surface, but differs in its yellow (vs. vivid purplish red) corolla and the angle between the midrib and the lateral veins of the leaf, which is acute as opposed to nearly at a right angle in C.hosokawae. Cirsiumtaiwanense has 2n = 32 chromosomes, which is different from the other species in the Taiwanese subsect. Australicirsium Kitam. (2n = 34). An identification key to the Cirsium taxa of Taiwan is presented.

4.
Mol Neurobiol ; 58(5): 2396-2406, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33421017

RESUMO

Proper development of neuronal cells is important for brain functions, and impairment of neuronal development may lead to neuronal disorders, implying that improvement in neuronal development may be a therapeutic direction for these diseases. Huntington's disease (HD) is a neurodegenerative disease characterized by impairment of neuronal structures, ultimately leading to neuronal death and dysfunctions of the central nervous system. Based on previous studies, fibroblast growth factor 9 (FGF9) may provide neuroprotective functions in HD, and FGFs may enhance neuronal development and neurite outgrowth. However, whether FGF9 can provide neuronal protective functions through improvement of neuronal morphology in HD is still unclear. Here, we study the effects of FGF9 on neuronal length in HD and attempt to understand the related working mechanisms. Taking advantage of striatal cell lines from HD knock-in mice, we found that FGF9 increases total neuronal length and upregulates several structural and synaptic proteins under HD conditions. In addition, activation of nuclear factor kappa B (NF-kB) signaling by FGF9 was observed to be significant in HD cells, and blockage of NF-kB leads to suppression of these structural and synaptic proteins induced by FGF9, suggesting the involvement of NF-kB signaling in these effects of FGF9. Taken these results together, FGF9 may enhance total neuronal length through upregulation of NF-kB signaling, and this mechanism could serve as an important mechanism for neuroprotective functions of FGF9 in HD.


Assuntos
Corpo Estriado/efeitos dos fármacos , Fator 9 de Crescimento de Fibroblastos/farmacologia , Doença de Huntington/metabolismo , NF-kappa B/metabolismo , Crescimento Neuronal/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Animais , Linhagem Celular , Corpo Estriado/metabolismo , Modelos Animais de Doenças , Camundongos , Neurônios/metabolismo , Transdução de Sinais/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos
5.
Life Sci ; 267: 118952, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33383048

RESUMO

AIMS: Huntington's disease (HD) is a neurodegenerative disease that causes deficits in neurite outgrowth, which suggests that enhancement of neurite outgrowth is a potential direction by which to improve HD. Our previous publications showed that fibroblast growth factor 9 (FGF9) provides anti-apoptosis and anti-oxidative functions in striatal cell models of HD through the extracellular signal-regulated kinases (ERK) pathway, and FGF9 also stimulates cytoskeletons to enhance neurite outgrowth via nuclear factor kappa B (NF-kB) signaling. In this study, we further demonstrate the importance of the ERK pathway for the neurite outgrowth induced by FGF9 in HD striatal models. MATERIALS AND METHODS: FGF9 was treated with ERK (U0126) or NF-kB (BAY11-7082) inhibitors in STHdhQ7/Q7 and STHdhQ111/Q111 striatal knock-in cell lines to examine neurite outgrowth, cytoskeletal markers, and synaptic proteins via immunofluorescence staining and Western blotting. NF-kB activity was analyzed by NF-kB promoter reporter assay. KEY FINDINGS: Here, we show that suppression of ERK signaling significantly inhibits FGF9-induced neurite outgrowth, cytoskeletal markers, and synaptic proteins in HD striatal cells. In addition, we also show suppression of ERK signaling significantly decreases FGF9-induced NF-kB activation, whereas suppression of NF-kB does not decrease FGF9-induced ERK signaling. These results suggest that FGF9 activates ERK signaling first, stimulates NF-kB upregulation, and then enhances neurite outgrowth in HD striatal cells. SIGNIFICANCE: We elucidate the more detailed mechanisms of neurite outgrowth enhanced by FGF9 in these HD striatal cells. This study may provide insights into targeting neurite outgrowth for HD therapy.


Assuntos
Fator 9 de Crescimento de Fibroblastos/metabolismo , Fator 9 de Crescimento de Fibroblastos/farmacologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Neuritos/metabolismo , Animais , Butadienos/farmacologia , Linhagem Celular , Células Cultivadas , Corpo Estriado/metabolismo , Inibidores Enzimáticos/farmacologia , Fator 9 de Crescimento de Fibroblastos/antagonistas & inibidores , Humanos , Proteína Huntingtina/genética , Proteína Huntingtina/metabolismo , Doença de Huntington/metabolismo , Camundongos , Camundongos Transgênicos , NF-kappa B/antagonistas & inibidores , NF-kappa B/metabolismo , Neuritos/efeitos dos fármacos , Crescimento Neuronal/fisiologia , Nitrilas/farmacologia , Proteínas Nucleares/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Proteínas Recombinantes/farmacologia , Transdução de Sinais , Sulfonas/farmacologia
6.
PhytoKeys ; (117): 119-132, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30804699

RESUMO

A new species of Cirsium, Cirsiumtatakaense Y.H.Tseng & C.Y.Chang, from central-southern Taiwan is described and illustrated. This species is similar to C.kawakamii Hayata in leaf shape, achene and chromosome number (2n = 64), but can be readily distinguished from C.kawakamii by the narrower leaf lobes, usually higher number of florets and phyllaries, the purplish-red corolla (vs. white) and larger pollen grains. A key to the species of Cirsium in Taiwan is also presented.

7.
Free Radic Biol Med ; 130: 256-266, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30391672

RESUMO

Huntington's disease (HD) is a heritable neurodegenerative disorder, and has been characterized as an increase of oxidative stress in brain regions. In our previous results, we showed fibroblast growth factor 9 (FGF9) provides neuroprotective functions to suppress cell death in HD striatal cells dominantly through ERK signalling. However, whether the working mechanism of FGF9 is related to anti-oxidative stress in HD is still unknown. In this study, STHdhQ7/Q7 (Q7) and STHdhQ111/Q111 (Q111) striatal knock-in cell lines were used to examine the neuroprotective effects of FGF9 against oxidative stress in HD. Results show that FGF9 alleviates oxidative stress induced by starvation in Q7 and Q111 cells. The treatment of FGF9 not only induces upregulation and activation of nuclear factor erythroid 2-like 2 (Nrf2), a critical transcription factor for anti-oxidative stress, but also further upregulates its downstream targets, such as superoxide dismutase 2, gamma-glutamylcysteine synthetase and glutathione reductase. Furthermore, blockage of the Nrf2 pathway abolishes the anti-oxidative functions of FGF9, and inhibition of ERK signalling reduces the activation of the FGF9-Nrf2 pathway, resulting in higher level of oxidative stress in HD cells. These results support the neuroprotective effects of FGF9 against oxidative stress through the ERK-Nrf2 pathway, and imply one of potential strategies for therapy of HD.


Assuntos
Antioxidantes/farmacologia , Encéfalo/metabolismo , Fator 9 de Crescimento de Fibroblastos/genética , Doença de Huntington/tratamento farmacológico , Fator 2 Relacionado a NF-E2/genética , Animais , Encéfalo/patologia , Linhagem Celular , Regulação da Expressão Gênica/efeitos dos fármacos , Glutamato-Cisteína Ligase/genética , Glutationa Redutase/genética , Humanos , Proteína Huntingtina/genética , Doença de Huntington/genética , Doença de Huntington/patologia , Sistema de Sinalização das MAP Quinases/genética , Camundongos , Fármacos Neuroprotetores/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Superóxido Dismutase/genética , Córtex Visual/metabolismo , Córtex Visual/patologia
8.
Cell Physiol Biochem ; 48(2): 605-617, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30021209

RESUMO

BACKGROUND/AIMS: Huntington's disease (HD) is a heritable neurodegenerative disorder, and there is no cure for HD to date. A type of fibroblast growth factor (FGF), FGF9, has been reported to play prosurvival roles in other neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. However, the effects of FGF9 on HD is still unknown. With many similarities in the cellular and pathological mechanisms that eventually cause cell death in neurodegenerative diseases, we hypothesize that FGF9 might provide neuroprotective functions in HD. METHODS: In this study, STHdhQ7/Q7 (WT) and STHdhQ111/Q111 (HD) striatal knock-in cell lines were used to evaluate the neuroprotective effects of FGF9. Cell proliferation, cell death and neuroprotective markers were determined via the MTT assay, propidium iodide staining and Western blotting, respectively. The signaling pathways regulated by FGF9 were demonstrated using Western blotting. Additionally, HD transgenic mouse models were used to further confirm the neuroprotective effects of FGF9 via ELISA, Western blotting and immunostaining. RESULTS: Results show that FGF9 not only enhances cell proliferation, but also alleviates cell death as cells under starvation stress. In addition, FGF9 significantly upregulates glial cell line-derived neurotrophic factor (GDNF) and an anti-apoptotic marker, Bcl-xL, and decreases the expression level of an apoptotic marker, cleaved caspase 3. Furthermore, FGF9 functions through ERK, AKT and JNK pathways. Especially, ERK pathway plays a critical role to influence the effects of FGF9 toward cell survival and GDNF production. CONCLUSIONS: These results not only show the neuroprotective effects of FGF9, but also clarify the critical mechanisms in HD cells, further providing an insight for the therapeutic potential of FGF9 in HD.


Assuntos
MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Fator 9 de Crescimento de Fibroblastos/farmacologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Animais , Apoptose/efeitos dos fármacos , Butadienos/farmacologia , Caspase 3/metabolismo , Linhagem Celular , MAP Quinases Reguladas por Sinal Extracelular/antagonistas & inibidores , Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Doença de Huntington/metabolismo , Doença de Huntington/patologia , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Camundongos , Camundongos Transgênicos , Nitrilas/farmacologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Córtex Visual/citologia , Córtex Visual/efeitos dos fármacos , Córtex Visual/metabolismo , Proteína bcl-X/metabolismo
9.
J Med Chem ; 61(3): 905-917, 2018 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-29304284

RESUMO

A series of bicyclic arylamino/heteroarylamino hydroxamic acids (7-31) have been examined as novel histone deacetylase 6 (HDAC6) inhibitors. One compound (13) exhibits remarkable inhibitory activity of HDAC6 with an IC50 value of 0.29 nM, which is 4,000-43,000 times more selective over other HDAC isoforms. Compound 13 was shown to have antiproliferative activity against human multiple myeloma RPMI 8226, U266, and NCI-H929 cells with no effect on normal bone marrow cells. Compound 13, as a single drug, suppresses the growth of tumors by a %TGI factor of 60.4% in human multiple myeloma RPMI 8226 xenograft models and, in combination with bortezomib, shows significant in vivo antitumor activity (%TGI = 86.2%). Compound 13 also demonstrates good human hepatocytic stability and high permeability, without any effect on mutagenicity and cytotoxicity. Thus, compound 13 is a potent HDAC6 inhibitor that could be developed for the treatment of multiple myeloma in the future.


Assuntos
Antineoplásicos/farmacologia , Desacetilase 6 de Histona/antagonistas & inibidores , Inibidores de Histona Desacetilases/farmacologia , Mieloma Múltiplo/patologia , Quinolinas/farmacologia , Animais , Antineoplásicos/química , Células CACO-2 , Proliferação de Células/efeitos dos fármacos , Inibidores de Histona Desacetilases/química , Humanos , Quinolinas/química , Ratos
10.
Theranostics ; 7(9): 2452-2462, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28744327

RESUMO

MicroRNAs (miRNAs) play important roles in several neurobiological processes, including the development and progression of diseases. Previously, we identified that one specific miRNA, miR-196a, provides neuroprotective effects on Huntington's disease (HD), although the detailed mechanism is still unclear. Based on our bioinformatic analyses, we hypothesize miR-196a might offer neuroprotective functions through improving cytoskeletons of brain cells. Here, we show that miR-196a could enhance neuronal morphology, further ameliorating intracellular transport, synaptic plasticity, neuronal activity, and learning and memory abilities. Additionally, we found that miR-196a could suppress the expression of RAN binding protein 10 (RANBP10) through binding to its 3' untranslated region, and higher expression of RANBP10 exacerbates neuronal morphology and intracellular transport. Furthermore, miR-196a enhances neuronal morphology through suppressing RANBP10 and increasing the ability of ß-tubulin polymerization. Most importantly, we observed higher expression of RANBP10 in the brains of HD transgenic mice, and higher expression of RANBP10 might exacerbate the pathological aggregates in HD. Taken together, we provide evidence that enhancement of neuronal morphology through RANBP10 is one of the neuroprotective mechanisms for miR-196a. Since miR-196a has also been reported in other neuronal diseases, this study might offer insights with regard to the therapeutic use of miR-196a in other neuronal diseases.


Assuntos
Fatores de Troca do Nucleotídeo Guanina/antagonistas & inibidores , Doença de Huntington/patologia , MicroRNAs/metabolismo , Proteínas Associadas aos Microtúbulos/antagonistas & inibidores , Neurônios/citologia , Neurônios/patologia , Neuroproteção , Animais , Modelos Animais de Doenças , Camundongos Transgênicos , Multimerização Proteica , Tubulina (Proteína)/metabolismo
11.
Eur J Med Chem ; 122: 92-101, 2016 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-27344487

RESUMO

This study reports the design and synthesis of 2-(phenylsulfonyl)quinoline N-hydroxyacrylamides (8a-k). Structure-activity relationship studies focusing on regio-effect of N-hydroxyacrylamide moiety and influence of the sulfonyl linker revealed that N-hydroxy-3-[3-(quinoline-2-sulfonyl)-phenyl]-acrylamide (8f) showed remarkable enzymatic and cellular activity. The GI50 values of 8f for HL-60, HCT116, PC-3, and A549 cells were found to be 0.29, 0.08, 0.15, and 0.27 µM, respectively. The compounds are therefore more potent than FDA approved PXD-101 and SAHA. They also have an effect on the acetylation degree of histone H3 and α-tubulin. In in vivo studies, 8f showed marked inhibition of the growth of HCT116 xenografts.


Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Inibidores de Histona Desacetilases/química , Inibidores de Histona Desacetilases/farmacologia , Histona Desacetilases/metabolismo , Quinolinas/química , Quinolinas/farmacologia , Animais , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Histonas/metabolismo , Humanos , Masculino , Camundongos , Relação Estrutura-Atividade , Tubulina (Proteína)/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
12.
Chem Sci ; 7(10): 6492-6498, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28451107

RESUMO

UiO-66 and analogues were successfully tailored to chemoselectively capture AsV oxyanions at the hydroxylated node and neutral AsIII species with the thiolated organic linkers. More efficient and faster uptake can be achieved with increasing defect densities, increasing pore aperture sizes, and decreasing particle sizes.

13.
Bioorg Med Chem ; 23(15): 4230-4236, 2015 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-26160020

RESUMO

This study reports the synthesis of a series of heteroaroyl-2-hydroxy-3,4,5-trimethoxybenzenes, which are potent antitubulin agents. Compound 13, (2-hydroxy-3,4,5-trimethoxyphenyl)-(6-methoxy-1H-indol-3-yl)-methanone exhibits marked antiproliferative activity against KB and MKN45 cells with IC50 values of 8.8 and 10.5 nM, respectively, binds strongly to the colchicine binding site and leads to inhibition of tubulin polymerization. It also behaves as a vascular disrupting agent which suppresses the formation of capillaries. The C2-OH group in the A-ring of this compound not only retains the biological activity but has valuable physicochemical properties.


Assuntos
Antimitóticos/química , Antimitóticos/farmacologia , Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores da Angiogênese/química , Inibidores da Angiogênese/farmacologia , Antimitóticos/metabolismo , Benzeno/química , Sítios de Ligação , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Técnicas de Química Sintética , Colchicina/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Células HT29/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Humanos , Concentração Inibidora 50 , Relação Estrutura-Atividade , Moduladores de Tubulina/química , Moduladores de Tubulina/metabolismo , Moduladores de Tubulina/farmacologia
14.
Brain Pathol ; 25(4): 481-90, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25178567

RESUMO

Huntington's disease (HD) is a genetic and neurodegenerative disease, leading to motor and cognitive dysfunction in HD patients. At cellular level, this disease is caused by the accumulation of mutant huntingtin (HTT) in different cells, and finally results in the dysfunction of different cells. To clean these mutant proteins, ubiquitin-proteasome system (UPS) and autophagy system are two critical pathways in the brain; however, little is known in other peripheral tissues. As mutant HTT affects different tissues progressively and might influence the UPS and autophagy pathways at early stages, we attempted to examine two clearance systems in HD models before the onset. Here, in vitro results showed that the accumulation of UPS signals with time was observed obviously in neuroblastoma and kidney cells, not in other cells. In HD transgenic mice, we observed the impairment of UPS, but not autophagy, over time in the cortex and striatum. In heart and muscle tissues, disturbance of autophagy was observed, whereas dysfunction of UPS was displayed in liver and lung. These results suggest that two protein clearance pathways are disturbed differentially in different tissues before the onset of HD, and enhancement of protein clearance at early stages might provide a potential stratagem to alleviate the progression of HD.


Assuntos
Doença de Huntington/genética , Doença de Huntington/patologia , Complexo de Endopeptidases do Proteassoma/genética , Ubiquitina/metabolismo , Animais , Autofagia/genética , Encéfalo/metabolismo , Encéfalo/patologia , Linhagem Celular , Modelos Animais de Doenças , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Proteína Huntingtina , Rim/metabolismo , Rim/patologia , Fígado/metabolismo , Fígado/patologia , Pulmão/metabolismo , Pulmão/patologia , Camundongos , Camundongos Transgênicos , Músculos/metabolismo , Músculos/patologia , Mutação/genética , Miocárdio/metabolismo , Miocárdio/patologia , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Neuroblastoma/patologia , Ubiquitina/genética
15.
Eur J Med Chem ; 77: 306-14, 2014 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-24657567

RESUMO

2-Hydroxy-3,4,5-trimethoxybenzophenones (8-16) manifest pseudo-ring formation involving intramolecular hydrogen bonding of the 2-OH and the carbonyl group. Among the synthetic products described in this report, (3-hydroxy-4-methoxyphenyl)(2-hydroxy-3,4,5-trimethoxyphenyl)-methanone (14) and (3-amino-4-methoxyphenyl)(2-hydroxy-3,4,5-trimethoxy-phenyl)methanone (16) exhibit significant antiproliferative activity against KB cells with IC50 values of 11.1 and 11.3 nM, respectively. These two compounds also displayed tubulin affinity comparable to that of combretastatin A-4. In studies with human umbilical vein endothelial cells, compounds 14 and 16 revealed concentration-dependent vascular-disrupting properties. The results support the rationale of the pseudo-ring concept and suggest further investigation of A-ring modification in these benzophenones.


Assuntos
Antimitóticos/farmacologia , Benzofenonas/farmacologia , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Antimitóticos/síntese química , Antimitóticos/química , Benzofenonas/síntese química , Benzofenonas/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Colchicina/antagonistas & inibidores , Relação Dose-Resposta a Droga , Células HT29 , Humanos , Células KB , Estrutura Molecular , Polimerização/efeitos dos fármacos , Relação Estrutura-Atividade , Tubulina (Proteína)/metabolismo
16.
Environ Sci Pollut Res Int ; 19(9): 3743-50, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23054736

RESUMO

INTRODUCTION: Solar wastewater treatment based on photocatalytic reactions is a green process that utilizes renewable energy resources and minimizes secondary pollution. Reactor design plays an important role in promoting treatment efficiency and throughput density (based on unit volume of the reactor). EXPERIMENTAL: A rotating disk reactor that significantly increases the process efficiency has been designed and evaluated for application to photocatalytic decomposition of dye pollutants in aqueous solutions. In this process, a novel multi-layer rotating disk reactor (MLRDR) was presented. Photocatalyst (TiO(2)) particles are immobilized on the surfaces of disks. Within each layer of the reactor, methyl orange aqueous solution is allowed to flow from the center of the disk in a radial direction along the surface of the disk, which is rotating at high speed and is irradiated with UV lamps. The effluent is then directed to the center of another layer that lies underneath. Up to four stacked layers have been tested in this study, and the effects due to the number of the layers and volumetric flow rate on reaction conversion are investigated. RESULTS AND DISCUSSION: The efficiency of this photocatalytic reactor exhibits complex dependence on these parameters. With selected operating conditions, conversions greater than 95% can be achieved within seconds of residence time. Design equations of the reactor have been derived based on fluid dynamics and kinetic models, and the simulation results show promising scale-up potential of the reactor.


Assuntos
Compostos Azo/química , Poluentes Químicos da Água/química , Catálise , Cinética , Modelos Químicos , Oxidantes Fotoquímicos/química , Fotólise , Titânio/química , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química
17.
J Org Chem ; 74(20): 7994-7, 2009 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-19761203

RESUMO

1-Bromo-2-phenylcyclopropene (2) underwent [2+2] dimerization to generate 1,2-dibromo-4,5-diphenyltricyclo[3.1.0.0(2,4)]hexane (5), which was heated to form 1,2-dibromo-4,5-diphenylcyclohexa-1,4-diene (6) followed by oxidation to yield 4',5'-dibromo-o-terphenyl (7). o-Terphenyl 7 could be synthesized in one-pot reactions from 1,1,2-tribromocyclopropane (3). When cyclopropane 3 was treated with 1.5 equiv of methyllithium followed by slowly adding the proton source, crossed [2+2] adduct 8 was isolated in 40% yield. Compound 8 was heated and oxidated to produce 4'-bromo-o-terphenyl (11).

18.
J Org Chem ; 69(25): 8949-51, 2004 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-15575781

RESUMO

1-Phenylcyclopropene (1) was synthesized by treatment of 1,1,2-tribromo-2-phenylcyclopropane (2) with 2.5 equiv of methyllithium followed by protonation. Compound 1 underwent ene dimerization to form ene dimer 5 followed by ene reaction with monomer 1 (enophile) to give an ene trimer 6. Both of these two ene reactions derived endo transition states. In the meantime, the [2+2] adduct, trans-1,2-diphenylbicyclo[3.1.0.0(2,4)]hexane (7), was also formed. When the adduct 7 was heated at THF refluxing temperature, 1,2-diphenylcyclohexa-1,4-diene (8) was obtained. Compound 8 was treated with DDQ to yield o-diphenylbenzene.


Assuntos
Ciclopropanos/química , Ciclopropanos/síntese química , Modelos Moleculares , Conformação Molecular , Pirrolidinonas/química , Estereoisomerismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA