Publications by authors named "Xixi Song"

26 Publications

  • Page 1 of 1

SERPINB10 contributes to asthma by inhibiting the apoptosis of allergenic Th2 cells.

Respir Res 2021 Jun 14;22(1):178. Epub 2021 Jun 14.

Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Xuhui District, Shanghai, 200032, China.

Background: Serine peptidase inhibitor, clade B, member 10 (SERPINB10) contributes to allergic inflammation in asthma. However, its role in the T-helper type 2 (Th2) response of allergic asthma is not known. The goal of this study was to unveil the function of SERPINB10 in the Th2 response of allergic asthma and the mechanism by which SERPINB10 affects the viability of Th2 cells.

Methods: Th2 cytokines and serum levels of house dust mite (HDM)-specific IgE in bronchoalveolar lavage fluid were examined by ELISA in an HDM-induced asthma model. The number and apoptosis of Th1 and Th2 cells in mouse lungs were measured by flow cytometry. Naïve CD4 T cells from patients with asthma were cultured under appropriate polarizing conditions to generate Th1 and Th2 cells. SERPINB10 expression in polarized Th1 and Th2 cells was quantified by real-time reverse transcription-quantitative polymerase chain reaction. SERPINB10 expression was knocked down in human CD4 T cells with lentivirus.

Results: Knockdown of SERPINB10 expression significantly diminished HDM-induced Th2 cytokine secretion and level of HDM-specific IgE. After HDM exposure, SERPINB10-knockdown mice had diminished numbers of Th2 cells, but similar numbers of Th1 cells, compared with those in negative-control mice. Th2 cells of SERPINB10-knockdown mice were more susceptible to apoptosis than that of control mice. Stimulating T-cell receptors (TCRs) with anti-CD3 antibody caused upregulation of SERPINB10 expression in polarized Th2 cells, but not polarized Th1 cells. Knockdown of SERPINB10 expression resulted in fewer numbers and greater apoptosis of polarized Th2 cells.

Conclusion: Our results suggest that SERPINB10 may contribute to allergic inflammation and the Th2 response of asthma by inhibiting the apoptosis of Th2 cells.
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http://dx.doi.org/10.1186/s12931-021-01757-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8201873PMC
June 2021

A new asymmetric activation strategy for hydrazones as acyl anion equivalents in the bimetallic catalyzed carbonyl-ene reaction.

Org Biomol Chem 2021 Mar;19(9):2055-2062

The College of Chemistry and Molecular Engineering, Zhengzhou University, 75 Daxue Road, Zhengzhou, Henan 450052, P. R. China.

A new asymmetric activation strategy for hydrazones as acyl anion equivalents is developed in the bimetallic catalyzed carbonyl-ene reaction of isatins and hydrazones. Under mild conditions, optically active functionalized 3-hydroxy-2-oxindoles were furnished in up to 98% yield with up to 97% enantioselectivity. In this process, formaldehyde tert-butylhydrazone which is seldom employed in asymmetric carbonyl-ene reactions accelerated by a metallic catalyst can be activated well by a Brønsted base. A possible catalytic cycle is proposed.
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http://dx.doi.org/10.1039/d1ob00017aDOI Listing
March 2021

Proteomic Analysis of Serum Differentially Expressed Proteins Between Allergic Bronchopulmonary Aspergillosis and Asthma.

Mycopathologia 2021 Mar 12;186(1):1-13. Epub 2020 Nov 12.

Department of Respiratory Medicine, Zhongshan Hospital, Fudan University, No. 180 Fenglin Road, Xuhui District, Shanghai, 200032, China.

Background: Allergic bronchopulmonary aspergillosis (ABPA) constantly develops in asthmatics, which has not been fully investigated.

Objectives: This study aimed to investigate serum differentially expressed proteins (DEPs) between ABPA and asthma using the new approach isobaric tags by relative and absolute quantitation (iTRAQ).

Methods: Each 16 serum samples from ABPA or asthmatic subjects were pooled and screened using iTRAQ. After bioinformatic analysis, five candidate DEPs were validated in the enlarged serum samples from additional 21 ABPA, 31 asthmatic and 20 healthy subjects using ELISA. A receiver operating characteristic (ROC) curve was used to estimate the diagnostic power of carnosine dipeptidase 1 (CNDP1).

Results: A total of 29 DEPs were screened out between ABPA and asthmatic groups. Over half of them were enriched in proteolysis and regulation of protein metabolic process. Further verification showed serum levels of immunoglobulin heavy constant gamma 1, α-1-acid glycoprotein 1, corticosteroid-binding globulin and vitronectin were neither differentially altered between ABPA and asthma nor consistent with the proteomic analysis. Only serum CNDP1 was significantly decreased in ABPA patients, compared with asthmatics and healthy controls (P < 0.01 and P < 0.05). The ROC analysis determined 10.73 ng/mL as the cutoff value of CNDP1, which could distinguish ABPA among asthmatics (AUC 0.770, 95%CI 0.632-0.875, P < 0.001).

Conclusions: This study firstly identified serological DEPs between ABPA and asthma using the new technique iTRAQ. Serum CNDP1 might assist the differential diagnosis of ABPA from asthma and serve as a new pathogenetic factor in fungal colonization and sensitization.
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http://dx.doi.org/10.1007/s11046-020-00506-0DOI Listing
March 2021

Possible Novel Therapeutic Targets in Lymphangioleiomyomatosis Treatment.

Front Med (Lausanne) 2020 24;7:554134. Epub 2020 Sep 24.

Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China.

Lymphangioleiomyomatosis (LAM) is a rare systemic neoplastic disease that exclusively happens in women. Studies focusing on LAM and tuberous sclerosis complex (TSC) have made great progress in understanding the pathogenesis and searching for treatment. The inactive mutation of TSC1 or TSC2 is found in patients with LAM to activate the crucial mammalian target of rapamycin (mTOR) signaling pathway and result in enhanced cell proliferation and migration. However, it does not explain every step of tumorigenesis in LAM. Because cessation of rapamycin would break the stabilization of lung function or improved quality of life and lead to disease recurrent, continued studies on the pathogenesis of LAM are necessary to identify novel targets and new treatment. Researchers have found several aberrant regulations that affect the mTOR pathway such as its upstream or downstream molecules and compensatory pathways in LAM. Some therapeutic targets have been under study in clinical trials. New methods like genome-wide association studies have located a novel gene related to LAM. Herein, we review the current knowledge regarding pathogenesis and treatment of LAM and summarize novel targets of therapeutic potential recently.
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http://dx.doi.org/10.3389/fmed.2020.554134DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7542236PMC
September 2020

Salidroside suppresses group 2 innate lymphoid cell-mediated allergic airway inflammation by targeting IL-33/ST2 axis.

Int Immunopharmacol 2020 Apr 15;81:106243. Epub 2020 Feb 15.

Department of Respiratory Medicine, Zhongshan Hospital, Fudan University, Shanghai, China. Electronic address:

Salidroside, an active component extracted from Rhodiola rosea, has been reported to inhibit allergic asthma. However, its mechanism has not been fully elucidated. Group 2 innate lymphoid cells (ILC2s) accumulate in the lung and cooperate with other cells to drive type 2 inflammation stimulated by inhaled allergens. The study aims to explore the suppressive effect of salidroside on ILC2s and IL-33/IL-33R (ST2) axis in allergic airway inflammation. The ovalbumin (OVA)-sensitized/challenged mice were established. Airway eosinophil recruitment, increased total IgE in the serum and type 2 cytokines IL-4, IL-5, and IL-13 in the bronchoalveolar lavage fluids and lung tissues were identified in the OVA-induced mice model, all of which were inhibited by pretreatment with different doses of salidroside. Moreover, salidroside suppressed lung total ILC2 and ST2-expressing ILC2 accumulation, lung IL-33 and ST2 expressions in mice. In vitro, OVA could induce IL-33 expression in BEAS-2B cells, which was also effectively inhibited by salidroside. This study firstly reveals salidroside as a potential therapeutic drug for allergic asthma by inhibiting ILC2-mediated airway inflammation via targeting IL-33/ST2 axis.
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http://dx.doi.org/10.1016/j.intimp.2020.106243DOI Listing
April 2020

Stereoselective Sequential Spirocyclopropanation/Cloke-Wilson Rearrangement Reactions for Synthesis of -β,γ-Disubstituted γ-Butyrolactones Using Alkylidene Meldrum's Acid and Benzyl Halides.

J Org Chem 2020 02 22;85(4):2266-2276. Epub 2020 Jan 22.

College of Chemistry , Zhengzhou University , No. 100 Science Avenue , Zhengzhou 450001 , P. R. China.

The stereoselective sequential spirocyclopropanation/Cloke-Wilson rearrangement reactions have been developed to synthesize γ-butyrolactones using alkylidene Meldrum's acids and benzyl halides. The DBU-promoted spirocyclopropanation was carried out efficiently at room temperature to generate -isomeric spirocyclopropyl Meldrum's acid, and the following stereospecific thermal decarboxylative Cloke-Wilson rearrangement afforded -γ-butyrolactones. A variety of aromatic and aliphatic Meldrum's acid derived olefins and benzyl halides were tolerated. Various -β,γ-disubstituted γ-butyrolactones were produced with moderate to good overall yields from 46 to 96% and excellent diastereoselectivities.
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http://dx.doi.org/10.1021/acs.joc.9b02978DOI Listing
February 2020

Chemoselective syntheses of spirodihydrofuryl and spirocyclopropyl barbiturates via cascade reactions of barbiturate-based olefins and acetylacetone.

Org Biomol Chem 2019 03;17(10):2684-2690

College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, P. R. China.

The Michael addition initiated ring closure reaction of barbiturate-based olefins and acetylacetone with NBS has been explored. The efficient and chemoselective approach for the synthesis of barbiturate-fused spirocycles was established. Spirodihydrofuryl barbiturates and spirocyclopropyl barbiturates were synthesized selectively via cascade reactions under different basic conditions in moderate to excellent yields. The structure of 2-(4-chlorophenyl)-1,1-diacetyl-5,7-dimethyl-5,7-diazaspiro[2,5]octane-4,6,8-trione was confirmed by single crystal X-ray diffraction analysis.
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http://dx.doi.org/10.1039/c9ob00004fDOI Listing
March 2019

Ghrelin serves as a signal of energy utilization and is involved in maintaining energy homeostasis in broilers.

Gen Comp Endocrinol 2019 02 30;272:76-82. Epub 2018 Nov 30.

College of Animal Science and Technology, Shandong Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, No. 61 Daizong Street, Taian 271018, PR China. Electronic address:

Ghrelin, one of the most important appetite regulating peptides, is involved in the regulation of energy homeostasis. The anorexia effect of ghrelin in chickens is contrary to that of ghrelin in mammals. In the present study, the effects of feeding status and dietary energy level on plasma total ghrelin levels and expression were studied in broilers. The gene expression of ghrelin and its receptor GHS-R1a were measured in the hypothalamus, proventriculus, duodenum, liver, and abdominal fat pad. The results showed that ghrelin mRNA and GHS-R1a mRNA are moderately expressed in liver and abdominal fat. Ghrelin secretion was increased by fasting and refeeding. The gene expression of ghrelin and GHS-R1a in the hypothalamus, proventriculus, liver, and abdominal fat pad were changed by feeding status and dietary energy level. The results suggest that ghrelin is a signal of energy utilization in chickens. The abundant expression of ghrelin and GHS-R1a in liver and abdominal fat pad may be associated with energy balance.
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http://dx.doi.org/10.1016/j.ygcen.2018.11.017DOI Listing
February 2019

Dexamethasone and insulin stimulate ghrelin secretion of broilers in a different way.

Gen Comp Endocrinol 2018 11 2;268:14-21. Epub 2018 Aug 2.

College of Animal Science and Veterinary Medicine, Shandong Agricultural University, No. 61 Daizong Street, Tai'an 271018, PR China. Electronic address:

Ghrelin is one of the most important appetite regulating peptides, involved in the regulation of energy homeostasis. The role of ghrelin on the appetite and fat metabolism in chickens is different from that of ghrelin in mammals. Glucocorticoids and insulin are important hormones and work differently in energy regulation of body. In this study, the effects of dexamethasone (DEX, 2.0 mg/kg BW), subcutaneous insulin injection (40 µg/kg BW), and glucose load on ghrelin secretion and expression were determined in broilers. DEX treatment increased circulating ghrelin concentration in broiler fed with either a low-energy diet (11.05 MJ/kg of metabolizable energy) or a high-energy diet (14.44 MJ/kg of metabolizable energy). The expression levels of ghrelin were increased while both ghrelin and its receptor GHS-R1a expression levels were stimulated by DEX. A single subcutaneous insulin injection (40 µg/kg BW) or oral glucose infusion (2 g/kg BW) rise circulating ghrelin level. Ghrelin expression in the proventriculus was increased by insulin treatment but unchanged by glucose load. DEX had no detectable influence on ghrelin and GHS-R1a expression in the hypohtalamus, whereas insulin suppressed their expression. In conclusion, both insulin and glucocorticoid stimulate ghrelin secretion in chickens, in contrast to mammals. Glucocorticoids evoke peripheral ghrelin/GHS-R1a system while insulin increases peripheral ghrelin expression and suppress the activation of central ghrelin/GHS-R1a system. The result suggests that ghrelin involved in the modulating network of energy homeostasis in concert with glucocorticoids and insulin.
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http://dx.doi.org/10.1016/j.ygcen.2018.07.009DOI Listing
November 2018

miR-92a regulates the expression levels of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 3 via sirtuin 1 signaling in hydrogen peroxide-induced vascular smooth muscle cells.

Mol Med Rep 2018 Jan 2;17(1):1041-1048. Epub 2017 Nov 2.

Department of Internal Medicine, Shanghai Dermatology Hospital, Tongji University, Shanghai 200443, P.R. China.

Vascular smooth muscle cells (VSMCs) exhibit a notably increased rate of migration, which is one of the most common pathological changes in atherosclerosis. Investigations into the role of micro (mi)RNAs in the regulation of VSMC migration are beginning to emerge and additional miRNAs involved in VSMC migration modulation require identification. In the current study, VSMCs were primarily cultured from rat thoracic aortas, transfected with miR‑92a mimics and induced by hydrogen peroxide (H2O2) for 24 h. Total mRNA and protein were collected for quantitative polymerase chain reaction and western blot analysis. In addition, the sirtuin 1 (SIRT1) gene was detected by luciferase reporter assay and VSMC migration was detected by Transwell migration assay. The current results demonstrated that reduced expression of miR‑92a and overexpression of SIRT1 at the mRNA level were observed in H2O2‑induced VSMCs. Furthermore, luciferase reporter assay demonstrated that the activity of the SIRT1 3'‑untranslated region was reduced by miR‑92a mimics. The upregulation of MMP9 and the downregulation of TIMP3 in H2O2‑induced VSMCs were observed to be reversed by miR‑92a mimics in addition to SIRT1 siRNA. Finally, Transwell migration assay revealed that miR‑92a overexpression and silencing SIRT1 mitigated VSMC migration following H2O2 treatment. The present study indicated that miR‑92a prevented the migration of H2O2‑induced VSMCs by repressing the expression of SIRT1, and also provided a novel therapy to protect against the phenotypic change of VSMCs in atherosclerosis.
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http://dx.doi.org/10.3892/mmr.2017.7937DOI Listing
January 2018

Activation of nuclear β-catenin/c-Myc axis promotes oxidative stress injury in streptozotocin-induced diabetic cardiomyopathy.

Biochem Biophys Res Commun 2017 12 6;493(4):1573-1580. Epub 2017 Oct 6.

Department of Internal Medicine, Shanghai Dermatology Hospital, Tongji University, Shanghai 200443, China.

Myocardial oxidative stress injury plays a crucial role in the pathogenesis of diabetic cardiomyopathy (DCM). Wnt/β-catenin signaling has been reported to involve in various heart diseases. However, the underlying mechanism associated with β-catenin in DCM remains elusive. This study intended to explore the effect of β-catenin on oxidative damage of DCM by establishing streptozotocin (STZ)-induced diabetic mouse model and hydrogen peroxide (HO)-treated myocardial cell model. Cardiac oxidative stress in DCM was detected by measurements of lipid peroxidation and anti-oxidative enzyme activities as well as DHE staining. Nuclear β-catenin activity and oxidative damage degree were measured by western blotting, qPCR, MTT assay and TUNEL staining. Cardiac function and morphology were evaluated by echocardiography and histopathology. Under diabetic oxidative stress or HO stimulation, nuclear β-catenin accumulation upregulated downstream c-Myc and further facilitated DNA damage and p53-mediated apoptosis as well as cell viability reduction, followed by phenotypic changes of cardiac dysfunction, interstitial fibrosis deposition and myocardial atrophy. Conversely, through directly inhibiting nuclear β-catenin/c-Myc axis, not only did siRNA knockdown of β-catenin or c-Myc attenuate cell injury in HO-stimulated cardiomyocytes, but also diabetic cardiac-specific β-catenin-knockout mice displayed the same prevention of heart injury as insulin-treated diabetic mice. The present study demonstrated that activated nuclear β-catenin/c-Myc axis was responsible for oxidative cardiac impairment of DCM. Therefore, repressing functional nuclear β-catenin may provide a hopeful therapeutic strategy for DCM.
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http://dx.doi.org/10.1016/j.bbrc.2017.10.027DOI Listing
December 2017

Overexpressing the Cu/Zn Superoxide Dismutase Increased Resistance to Oxidative Stress in Transgenic .

Front Plant Sci 2017 13;8:1010. Epub 2017 Jun 13.

State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of ForestryBeijing, China.

Superoxide dismutase (SOD) is a very important reactive oxygen species (ROS)-scavenging enzyme. In this study, the functions of a gene (), from , a cadmium (Cd)/zinc/lead co-hyperaccumulator of the Crassulaceae, was characterized. The expression of was induced by Cd stress. Compared with wild-type (WT) plants, overexpression of gene in transgenic plants enhanced the antioxidative defense capacity, including SOD and peroxidase activities. Additionally, it reduced the damage associated with the overproduction of hydrogen peroxide (HO) and superoxide radicals (O). The influence of Cd stress on ion flux across the root surface showed that overexpressing in transgenic plants has greater Cd uptake capacity existed in roots. A co-expression network based on microarray data showed possible oxidative regulation in after Cd-induced oxidative stress, suggesting that S may participate in this network and enhance ROS-scavenging capability under Cd stress. Taken together, these results suggest that overexpressing increased oxidative stress resistance in transgenic and provide useful information for understanding the role of in response to abiotic stress.
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http://dx.doi.org/10.3389/fpls.2017.01010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5469215PMC
June 2017

Functional Characterization of a Gene in Sedum alfredii Hance Resembling Rubber Elongation Factor Endowed with Functions Associated with Cadmium Tolerance.

Front Plant Sci 2016 29;7:965. Epub 2016 Jun 29.

State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, BeijingChina; Key Laboratory of Tree Breeding of Zhejiang Province, The Research Institute of Subtropical Forestry, Chinese Academy of Forestry, HangzhouChina.

Cadmium is a major toxic heavy-metal pollutant considering their bioaccumulation potential and persistence in the environment. The hyperaccumulating ecotype of Sedum alfredii Hance is a Zn/Cd co-hyperaccumulator inhabiting in a region of China with soils rich in Pb/Zn. Investigations into the underlying molecular regulatory mechanisms of Cd tolerance are of substantial interest. Here, library screening for genes related to cadmium tolerance identified a gene resembling the rubber elongation factor gene designated as SaREFl. The heterologous expression of SaREFl rescued the growth of a transformed Cd-sensitive strain (ycf1). Furthermore, SaREFl-expressing Arabidopsis plants were more tolerant to cadmium stress compared with wild type by measuring parameters of root length, fresh weight and physiological indexes. When under four different heavy metal treatments, we found that SaREFl responded most strongly to Cd and the root was the plant organ most sensitive to this heavy metal. Yeast two-hybrid screening of SaREFl as a bait led to the identification of five possible interacting targets in Sedum alfredii Hance. Among them, a gene annotated as prenylated Rab acceptor 1 (PRA1) domain protein was detected with a high frequency. Moreover, subcellular localization of SaREF1-GFP fusion protein revealed some patchy spots in cytosol suggesting potential association with organelles for its cellular functions. Our findings would further enrich the connotation of REF-like genes and provide theoretical assistance for the application in breeding heavy metal-tolerant plants.
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http://dx.doi.org/10.3389/fpls.2016.00965DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4925709PMC
July 2016

Integration of small RNAs, degradome and transcriptome sequencing in hyperaccumulator Sedum alfredii uncovers a complex regulatory network and provides insights into cadmium phytoremediation.

Plant Biotechnol J 2016 06 23;14(6):1470-83. Epub 2016 Jan 23.

State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing, China.

The hyperaccumulating ecotype of Sedum alfredii Hance is a cadmium (Cd)/zinc/lead co-hyperaccumulating species of Crassulaceae. It is a promising phytoremediation candidate accumulating substantial heavy metal ions without obvious signs of poisoning. However, few studies have focused on the regulatory roles of miRNAs and their targets in the hyperaccumulating ecotype of S. alfredii. Here, we combined analyses of the transcriptomics, sRNAs and the degradome to generate a comprehensive resource focused on identifying key regulatory miRNA-target circuits under Cd stress. A total of 87 721 unigenes and 356 miRNAs were identified by deep sequencing, and 79 miRNAs were differentially expressed under Cd stress. Furthermore, 754 target genes of 194 miRNAs were validated by degradome sequencing. A gene ontology (GO) enrichment analysis of differential miRNA targets revealed that auxin, redox-related secondary metabolism and metal transport pathways responded to Cd stress. An integrated analysis uncovered 39 pairs of miRNA targets that displayed negatively correlated expression profiles. Ten miRNA-target pairs also exhibited negative correlations according to a real-time quantitative PCR analysis. Moreover, a coexpression regulatory network was constructed based on profiles of differentially expressed genes. Two hub genes, ARF4 (auxin response factor 4) and AAP3 (amino acid permease 3), which might play central roles in the regulation of Cd-responsive genes, were uncovered. These results suggest that comprehensive analyses of the transcriptomics, sRNAs and the degradome provided a useful platform for investigating Cd hyperaccumulation in S. alfredii, and may provide new insights into the genetic engineering of phytoremediation.
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http://dx.doi.org/10.1111/pbi.12512DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066797PMC
June 2016

Overexpression of quinone reductase from Salix matsudana Koidz enhances salt tolerance in transgenic Arabidopsis thaliana.

Gene 2016 Jan 2;576(1 Pt 3):520-7. Epub 2015 Nov 2.

State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, China; Key Laboratory of Tree Breeding of Zhejiang Province, The Research Institute of Subtropical of Forestry, Chinese Academy of Forestry, China. Electronic address:

Quinone reductase (QR) is an oxidative-related gene and few studies have focused on its roles concerning salt stress tolerance in plants. In this study, we cloned and analyzed the QR gene from Salix matsudana, a willow with tolerance of moderate salinity. The 612-bp cDNA corresponding to SmQR encodes 203 amino acids. Expression of SmQR in Escherichia coli cells enhanced their tolerance under salt stress. In addition, transgenic Arabidopsis thaliana lines overexpressing SmQR exhibited higher salt tolerance as compared with WT, with higher QR activity and antioxidant enzyme activity as well as higher chlorophyll content, lower methane dicarboxylic aldehyde (MDA) content and electric conductivity under salt stress. Nitro blue tetrazolium (NBT) and 3,3'-diaminobenzidine (DAB) staining also indicated that the transgenic plants accumulated less reactive oxygen species compared to WT when exposed to salt stress. Overall, our results suggested that SmQR plays a significant role in salt tolerance and that this gene may be useful for biotechnological development of plants with improved tolerance of salinity.
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http://dx.doi.org/10.1016/j.gene.2015.10.069DOI Listing
January 2016

A New Strategy for Enantioselective Construction of Multisubstituted Five-Membered Oxygen Heterocycles via a Domino Michael/Hemiketalization Reaction.

Chemistry 2015 Aug 14;21(34):11994-8. Epub 2015 Jul 14.

College of Chemistry and Molecular Engineering, Zhengzhou University, 75, Daxue Street, Zhengzhou City, 450052 (China).

A new highly enantioselective domino Michael/hemiketalization reaction of α-hydroxyacetophenone with β,γ-unsaturated α-keto esters for the synthesis of 2,2,4,5-tetrasubstituted chiral tetrahydrofurans is reported. With 2 mol % intramolecular dinuclear zinc-AzePhenol complex prepared in situ from the reaction of multidentate semi-azacrown ether ligand with ZnEt2 , the corresponding anti-multisubstituted tetrahydrofuran products were obtained in up to 90 % yields, and 98 % enantiomeric excess (ee) at 0 °C for 45 min. Moreover, the products were easily converted to 2,3,5-trisubstituted 2,3-dihydrofurans without any loss in optical activity.
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http://dx.doi.org/10.1002/chem.201501655DOI Listing
August 2015

Enantioselective Friedel-Crafts alkylation of pyrrole with chalcones catalyzed by a dinuclear zinc catalyst.

J Org Chem 2014 Dec 20;79(23):11690-9. Epub 2014 Nov 20.

College of Chemistry and Molecular Engineering, Zhengzhou University , No. 75, Daxue Street, Zhengzhou City, Henan Province 450052, P. R. China.

A highly enantioselective Friedel-Crafts (F-C) alkylation of pyrrole with a wide range of simple nonchelating chalcone derivatives catalyzed by a chiral (Zn2EtL)n (L = (S,S)-1) complex has been developed. The catalyst (Zn2EtL)n complex was prepared in situ by reacting the chiral ligand (S,S)-1 with 2 equiv of diethylzinc. A series of β-pyrrole-substituted dihydrochalcones were usually formed mostly in excellent yields (up to 99%) and excellent enantioselectivity [up to 99% enantiomeric excess (ee)] by using 15 mol % catalyst loading under mild conditions. The absolute stereochemistry of the products was determined to be the S-configuration by X-ray crystallographic analysis of 13g. Meanwhile, a weak negative nonlinear effect was observed. On the basis of the experimental results and previous reports, a possible mechanism was proposed to explain the origin of the asymmetric induction.
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http://dx.doi.org/10.1021/jo5023712DOI Listing
December 2014

Diastereomeric aziridine carbinol catalyzed enantioselective arylation reaction: toward the asymmetric synthesis of both enantiomers of chiral 3-aryl phthalide.

J Org Chem 2014 Jul 13;79(13):6087-93. Epub 2014 Jun 13.

The College of Chemistry and Molecular Engineering, Zhengzhou University , No. 75 Daxue Road, Zhengzhou, Henan Province 450052, P. R. China.

The diastereomeric aziridine carbinols are applied, respectively, as efficient chiral ligand in the catalysis of asymmetric arylation and sequential arylation-lactonization cascade. The two diastereomers, which are facilely synthesized from the same chiral source, function as pseudo enantiomers in arylation of aromatic aldehydes providing the different enantiomers of the diarylmethanols with almost the same excellent enantioselectivities. The arylation method is also carried out in tandem with lactonization process to afford a concise synthetic approach to both enantiomers of optically active 3-aryl phthalide.
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http://dx.doi.org/10.1021/jo500796wDOI Listing
July 2014

Construction of chiral bridged tricyclic benzopyrans: enantioselective catalytic Diels-Alder reaction and a one-pot reduction/acid-catalyzed stereoselective cyclization.

Angew Chem Int Ed Engl 2014 May 24;53(19):4940-4. Epub 2014 Mar 24.

Department of Chemistry & Chemical Biology, University of New Mexico, Albuquerque, NM 87131 (USA) http://chemistry.unm.edu/faculty_bio/wwang.html.

An asymmetric two-step approach to chiral bridged tricyclic benzopyrans, core structures featured in various natural products, is described. In the synthesis, an unprecedented enantioselective catalytic decarboxylative Diels-Alder reaction is developed using readily available coumarin-3-carboxylic acids and aldehydes as reactants under mild reaction conditions. Notably, the decarboxylation-assisted release of the catalyst enables the process to proceed efficiently with high enantio- and diastereoselectivity. Furthermore, a one-pot procedure for either a LiAlH4 - or NaBH4 -mediated reduction with subsequent acid-catalyzed intramolecular cyclization of the Diels-Alder adducts was identified for the efficient formation of the chiral bridged tricyclic benzopyrans.
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http://dx.doi.org/10.1002/anie.201402170DOI Listing
May 2014

Synthesis of benzoxazoles via an amine-catalyzed [4 + 1] annulation.

Org Lett 2013 May 8;15(10):2510-3. Epub 2013 May 8.

Department of Chemistry and Chemical Biology, University of New Mexico , Albuqueruqe, New Mexico 87131-0001, United States, and School of Pharmacy, East China University of Science & Technology , Shanghai 200237, China.

An unprecedented simple pyrrolidine catalyzed [4 + 1] annulation reaction of ynals with N-protected-2-aminophenols is reported. The utilization of the unique property and reactivity of the C≡C triple bond in ynals leads to two consecutive conjugate addition reactions at the same β-position with pyrrolidine via iminium activation. The powerful cascade process affords a new alternative approach to biologically and synthetically important benzoxazoles in high yields (83-95%).
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http://dx.doi.org/10.1021/ol400988eDOI Listing
May 2013

Ionic liquids dispersive liquid-liquid microextraction and HPLC-atomic fluorescence spectrometric determination of mercury species in environmental waters.

J Sep Sci 2013 Jan 15;36(2):414-20. Epub 2012 Dec 15.

College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, P R China.

An ionic liquid (IL) based dispersive liquid-liquid microextraction combined with HPLC hydride generation atomic fluorescence spectrometry method for the preconcentration and determination of mercury species in environmental water samples is described. Four mercury species (MeHg(+), EtHg(+), PhHg(+), and Hg(2+)) were complexed with dithionate and the neutral chelates were extracted into IL drops using dispersive liquid-liquid microextraction. Variables affecting the formation and extraction of mercury dithizonates were optimized. The optimum conditions found were as follows: IL-type and amount, 0.05 g of 1-octyl-3-methylimidazolium hexafluorophosphate; dispersive solvents type and amount, 500 μL of acetone; pH, 6; extraction time, 2 min; centrifugation time, 12 min; and no sodium chloride addition. Under the optimized conditions, the detection limits of the analytes were 0.031 μg/L for Hg(2+), 0.016 μg/L for MeHg(+), 0.024 μg/L for EtHg(+), and 0.092 μg/L for PhHg(+), respectively. The repeatability of the method, expressed as RSD, was between 1.4 and 5.2% (n = 10), and the average recoveries for spiked test were 96.9% for Hg(2+), 90.9% for MeHg(+), 90.5% for EtHg(+), 92.3% for PhHg(+), respectively. The developed method was successfully applied for the speciation of mercury in environmental water samples.
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http://dx.doi.org/10.1002/jssc.201200571DOI Listing
January 2013

Direct transformation of simple enals to 3,4-disubstituted benzaldehydes under mild reaction conditions via an organocatalytic regio- and chemoselective dimerization cascade.

Chemistry 2012 Aug 28;18(32):9770-4. Epub 2012 Jun 28.

Department of Chemistry and Chemical Biology, University of New Mexico, MSC03 2060, Albuquerque, NM 87131-0001, USA.

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http://dx.doi.org/10.1002/chem.201201709DOI Listing
August 2012

An organocatalytic cascade approach toward polysubstituted quinolines and chiral 1,4-dihydroquinolines-unanticipated effect of N-protecting groups.

Angew Chem Int Ed Engl 2012 Jul 13;51(29):7282-6. Epub 2012 Jun 13.

Department of Chemistry & Chemical Biology, University of New Mexico, MSC03 2060, Albuquerque, NM 87131-0001, USA.

A matter of protection: The outcome of a divergent organocatalytic aza-Michael/aldol cascade process toward quinolines and 1,4-dihydroquinolines depends on the choice of the N-protecting group (see scheme; TEA = triethylamine, TMS = trimethylsilyl). Use of an electron-donating sulfonyl group results in an unanticipated aza-Michael/aldol/aromatization cascade to give polysubstituted quinolines (right). In contrast, chiral 1,4-dihydroquinolines are obtained with an electron-withdrawing sulfonyl group (left).
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http://dx.doi.org/10.1002/anie.201202161DOI Listing
July 2012

Total synthesis of polyene natural product dihydroxerulin by mild organocatalyzed dehydrogenation of alcohols.

Chemistry 2012 Feb 25;18(8):2230-4. Epub 2012 Jan 25.

Department of Chemistry & Chemical Biology, University of New Mexico, MSC03 2060, Albuquerque, NM 87131-0001, USA.

Polyene synthesis: An efficient approach to the total synthesis of polyene natural product dihydroxrulin (1) is described. A novel, mild, direct organocatalytic IBX-mediated dehydrogenation process of simple alcohols to enals has been developed, which serves as a key step in the synthesis (see scheme).
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http://dx.doi.org/10.1002/chem.201103325DOI Listing
February 2012

Direct stereoselective α-arylation of unmodified enals using an organocatalytic cross-coupling-like reaction.

Nat Commun 2011 Nov 8;2:524. Epub 2011 Nov 8.

Department of Chemistry & Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA.

Cross-coupling reactions typically rely on the use of transition metal catalysis. However, although achieving this process using metal-free organocatalysts is highly challenging, it could offer unique opportunities to discover novel bond-forming strategies in organic synthesis. Here we report a new amine catalysed direct stereoselective C-H α-arylation reaction of unmodified enals with bromoarenes. The power of this process, which involves an unprecedented iminium-Michael-alkylation-enamine-retro-Michael cascade sequence, has been demonstrated in the context of direct α-functionalization reactions of simple, unmodified enals with 4-bromophenols, 1-bromo-2-naphthol and 3-bromoindoles under mild reaction conditions. Notably, the process can be used for highly stereoselective syntheses of non-readily accessible E isomers, which normally require the use of transition metal-promoted cross-couplings and functionalized enals. The results of these studies significantly expand the scope of aminocatalysis.
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http://dx.doi.org/10.1038/ncomms1541DOI Listing
November 2011

Organocatalytic asymmetric synthesis of chiral fluorinated quaternary carbon containing beta-ketoesters.

Chem Commun (Camb) 2009 Apr 12(16):2136-8. Epub 2009 Mar 12.

Department of Chemistry, University of New Mexico, Albuquerque, NM 87131, USA.

Organocatalytic enantioselective conjugate addition of alpha-fluoroketoesters to nitroolefins efficiently catalyzed by a cinchona alkaloid-derivative affords versatile non-enolizable ketoesters by forming two consecutive fluorinated quaternary and tertiary chiral carbon centers with excellent enantioselectivity.
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http://dx.doi.org/10.1039/b900777fDOI Listing
April 2009
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