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1.
Sci Adv ; 9(51): eadk1704, 2023 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-38117883

RESUMO

Here, an Ir/Zn-cocatalyzed atroposelective [2+2+2] cycloaddition of 1,6-diynes and ynamines was developed, forging various functionalized C─N axially chiral indoles and pyrroles in generally good to excellent yields (up to 99%), excellent chemoselectivities, and high enantioselectivities (up to 98% enantiomeric excess) with wide substrate scope. This cocatalyzed strategy not only provided an alternative promising and reliable way for asymmetric alkyne [2+2+2] cyclotrimerization in an easy handle but also settled the issues of previous [Rh(COD)2]BF4-catalyzed system on the construction of C─N axial chirality such as complex operations, limited substrate scope, and low efficiency. In addition, control experiments and theoretical calculations disclosed that Zn(OTf)2 markedly reduced the barrier of migration insertion to significantly increase reaction efficiency, which was distinctly different from previous work on the Lewis acid for improving reaction yield through accelerating oxidative addition and reductive elimination.

3.
Plant Biotechnol J ; 16(1): 151-164, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-28500777

RESUMO

Although starch degradation has been well studied in model systems such as Arabidopsis leaves and cereal seeds, this process in starchy fruits during ripening, especially in bananas, is largely unknown. In this study, 38 genes encoding starch degradation-related proteins were identified and characterized from banana fruit. Expression analysis revealed that 27 candidate genes were significantly induced during banana fruit ripening, with concomitant conversion of starch-to-sugars. Furthermore, iTRAQ-based proteomics experiments identified 18 starch degradation-associated enzymes bound to the surface of starch granules, of which 10 were markedly up-regulated during ripening. More importantly, a novel bHLH transcription factor, MabHLH6, was identified based on a yeast one-hybrid screening using MaGWD1 promoter as a bait. Transcript and protein levels of MabHLH6 were also increased during fruit ripening. Electrophoretic mobility shift assays, chromatin immunoprecipitation and transient expression experiments confirmed that MabHLH6 activates the promoters of 11 starch degradation-related genes, including MaGWD1, MaLSF2, MaBAM1, MaBAM2, MaBAM8, MaBAM10, MaAMY3, MaAMY3C, MaISA2, MaISA3 and MapGlcT2-2 by recognizing their E-box (CANNTG) motifs present in the promoters. Collectively, these findings suggest that starch degradation during banana fruit ripening may be attributed to the complex actions of numerous enzymes related to starch breakdown at transcriptional and translational levels, and that MabHLH6 may act as a positive regulator of this process via direct activation of a series of starch degradation-related genes.


Assuntos
Frutas/metabolismo , Musa/metabolismo , Proteínas de Plantas/metabolismo , Amido/metabolismo , Frutas/genética , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Musa/genética , Proteínas de Plantas/genética , Regiões Promotoras Genéticas/genética , Ativação Transcricional/genética , Ativação Transcricional/fisiologia
4.
Front Plant Sci ; 7: 1021, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27462342

RESUMO

Ethylene plays an essential role in many biological processes including fruit ripening via modulation of ethylene signaling pathway. Ethylene Response Factors (ERFs) are key transcription factors (TFs) involved in ethylene perception and are divided into AP2, RAV, ERF, and DREB sub-families. Although a number of studies have implicated the involvement of DREB sub-family genes in stress responses, little is known about their roles in fruit ripening. In this study, we identified a DREB TF with a EAR motif, designated as MaDEAR1, which is a nucleus-localized transcriptional repressor. Expression analysis indicated that MaDEAR1 expression was repressed by ethylene, with reduced levels of histone H3 and H4 acetylation at its regulatory regions during fruit ripening. In addition, MaDEAR1 promoter activity was also suppressed in response to ethylene treatment. More importantly, MaDEAR1 directly binds to the DRE/CRT motifs in promoters of several cell wall-modifying genes including MaEXP1/3, MaPG1, MaXTH10, MaPL3, and MaPME3 associated with fruit softening during ripening and represses their activities. These data suggest that MaDEAR1 acts as a transcriptional repressor of cell wall-modifying genes, and may be negatively involved in ethylene-mediated ripening of banana fruit. Our findings provide new insights into the involvement of DREB TFs in the regulation of fruit ripening.

5.
Sci Rep ; 6: 23632, 2016 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-27004441

RESUMO

Most harvested fruits and vegetables are stored at low temperature but many of them are highly sensitive to chilling injury. Jasmonic acid (JA), a plant hormone associated with various stress responses, is known to reduce chilling injury in fruits. However, little is known about the transcriptional regulation of JA biosynthesis in relation to cold response of fruits. Here, we show the involvement of a Group I WRKY transcription factor (TF) from banana fruit, MaWRKY26, in regulating JA biosynthesis. MaWRKY26 was found to be nuclear-localized with transcriptional activation property. MaWRKY26 was induced by cold stress or by methyl jasmonate (MeJA), which enhances cold tolerance in banana fruit. More importantly, MaWRKY26 transactivated JA biosynthetic genes MaLOX2, MaAOS3 and MaOPR3 via binding to their promoters. Further, MaWRKY26 physically interacted with a VQ motif-containing protein MaVQ5, and the interaction attenuated MaWRKY26-induced transactivation of JA biosynthetic genes. These results strongly suggest that MaVQ5 might act as a repressor of MaWRKY26 in activating JA biosynthesis. Taken together, our findings provide new insights into the transcriptional regulation of JA biosynthesis in response to cold stress and a better understanding of the molecular aspects of chilling injury in banana fruit.


Assuntos
Ciclopentanos/metabolismo , Musa/fisiologia , Oxilipinas/metabolismo , Estresse Fisiológico , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Vias Biossintéticas , Núcleo Celular/metabolismo , Temperatura Baixa , Regulação da Expressão Gênica de Plantas , Musa/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regiões Promotoras Genéticas , Ligação Proteica
6.
J Ethnopharmacol ; 137(3): 1089-94, 2011 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-21798328

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Siegesbeckia orientalis has been traditionally used as a topical anti-inflammatory and analgesic agent. AIMS OF THE STUDY: Current study was designed to explore the topical anti-inflammatory and analgesic effects of a constituent isolated from Siegesbeckia orientalis (Compositae), in order to validate its folk use. MATERIALS AND METHODS: Kirenol was isolated from ethanolic extract of Siegesbeckia orientalis. Several topical formulations containing kirenol were investigated for anti-inflammatory and analgesic activities in rat. The effects were studied using carrageenan-induced rat acute inflammation model, complete Freund's adjuvant (CFA)-induced chronic inflammation and formalin test in rats. Piroxicam gel and methyl salicylate ointment were studied as positive control for anti-inflammatory and analgesic activity, respectively. RESULTS: The anti-inflammatory effect of kirenol 0.4-0.5% (w/w) was similar to the effect of piroxicam gel 4h after carrageenan injection. The analgesic activity of topical preparation with more than 0.4% (w/w) was observed in the late phase. These effects may be due, at least in part, to the pro-inflammatory cytokine production of IL-1ß and TNF-α. The administration of kirenol cream at the dose of 0.3, 0.4 and 0.5% (w/w) significantly inhibited the development of joint swelling induced by CFA, which was auxiliary supported by histopathological studies. CONCLUSION: Kirenol has demonstrated its significant potential to be further investigated for its discovery as a new lead compound for management of topical pain and inflammation, although further pharmacological research is necessary to fully understand its mechanism of action. It also supports the potential beneficial effect of topically administered Siegesbeckia orientalis in inflammatory diseases.


Assuntos
Analgésicos/farmacologia , Artrite Experimental/prevenção & controle , Asteraceae , Diterpenos/farmacologia , Medicamentos de Ervas Chinesas/farmacologia , Inflamação/prevenção & controle , Dor/prevenção & controle , Administração Tópica , Analgésicos/administração & dosagem , Analgésicos/isolamento & purificação , Animais , Anti-Inflamatórios/administração & dosagem , Anti-Inflamatórios/isolamento & purificação , Anti-Inflamatórios/farmacologia , Artrite Experimental/induzido quimicamente , Artrite Experimental/imunologia , Asteraceae/química , Carragenina , Diterpenos/administração & dosagem , Diterpenos/isolamento & purificação , Relação Dose-Resposta a Droga , Medicamentos de Ervas Chinesas/administração & dosagem , Medicamentos de Ervas Chinesas/isolamento & purificação , Etanol/química , Formaldeído , Adjuvante de Freund , Inflamação/induzido quimicamente , Inflamação/imunologia , Mediadores da Inflamação/metabolismo , Interleucina-1beta/metabolismo , Dor/induzido quimicamente , Dor/imunologia , Piroxicam/farmacologia , Componentes Aéreos da Planta , Plantas Medicinais , Ratos , Salicilatos/farmacologia , Solventes/química , Fatores de Tempo , Fator de Necrose Tumoral alfa/metabolismo
7.
Artigo em Chinês | MEDLINE | ID: mdl-20137405

RESUMO

OBJECTIVE: To establish the biological exposure limit values of urinary S-phenylmercapturic acid (SPMA) for assessing occupational exposure to benzene. METHODS: Study participants were selected from 55 workers of benzene exposures below 32.5 mg/m(3). The concentration of personal exposure to benzene was measured by gas chromatography and sampled with personal sampler. The urine samples were collected at the end of work shift and individual internal exposure level was evaluated by determination of SPMA in urine by HPLC/MS method. Comparison of external and internal exposure was assessed by the relative internal exposure (RIE) index. RESULTS: The benzene exposure level ranged from 0.71 to 32.17 mg/m(3) (geometric mean 6.98 mg/m(3), median 7.50 mg/m(3)). The urinary SPMA at the end of the work shift were significantly correlated with benzene exposure, (microg/g Cr) = -8.625 + 18.367X (mg/m(3)), r = 0.8035, (P < 0.01). According to the occupational exposure limit for benzene in China and calculation of regression equation, the expected value of urinary SPMA was 101.58 microg/g Cr. Mean level of biotransformation of per mg/m(3) benzene to urinary SPMA was 18.23 microg/g Cr and the metabolic efficiencies of benzene transformation to urinary SPMA decreased with benzene exposure increased. CONCLUSION: Based on abroad documents and data, biological limit value for occupational exposure to benzene in China is recommended as follows: 100 microg/g Cr (47 micromol/mol Cr) for SPMA in the urine at the end of shift.


Assuntos
Acetilcisteína/análogos & derivados , Derivados de Benzeno/urina , Benzeno/efeitos adversos , Exposição Ocupacional/efeitos adversos , Acetilcisteína/urina , Adulto , Benzeno/análise , China , Humanos , Pessoa de Meia-Idade , Exposição Ocupacional/análise , Níveis Máximos Permitidos , Adulto Jovem
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