Xiang Yu

Oak Ridge National Laboratory, Oak Ridge, Florida, United States

Are you Xiang Yu?

Claim your profile

Publications (44)164.11 Total impact

  • Huan Qu · Min Lv · Xiang Yu · Xihong Lian · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: By structural modification of piperine, some piperine-based phenylsulfonylhydrazone derivatives exhibited an unprecedented and potent narcotic activity against the oriental armyworm, Mythimna separata (Walker). The ND50 values of compounds 6c and 6e against the third-instar larvae of M. separata, which were more potent than those of wilfortrine and wilforgine, were 0.0074 μmol (after 3.5 h), and 0.0075 μmol (after 7 h) per larvae, respectively. By transmission electron microscope, it demonstrated that mitochondria were vacuolated and swollen in the ganglion cell of M. separata after treatment with 6c. More importantly, 6c selectively displayed the inhibition activity on acetylcholine esterase (AchE) of M. separata. This work paved the way for further studying the insecticidal mechanism of 6c as a new and promising botanical narcotic agent.
    Scientific Reports 08/2015; 5:13077. DOI:10.1038/srep13077 · 5.58 Impact Factor
  • Xiang Yu · Danfeng Shi · Xiaoyan Zhi · Qin Li · Xiaojun Yao · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: As part of our ongoing search for new insecticidal agents originating from natural products, in the present paper, we have prepared a series of C7-oxime ester derivatives of obacunone and evaluated their insecticidal activity at 1 mg/mL against the pre-third-instar larvae of oriental armyworm (Mythimna separata Walker), a typical lepidopteran pest. The structures of all target compounds were well characterized by 1H NMR, HRMS, optical rotation, IR, and mp. More importantly, three key steric structures of 3m, 3r, and 3s were unambiguously determined by single-crystal X-ray diffraction. Compounds 3e, 3r, 3s and 3w exhibited the more promising insecticidal activity with the final mortality rates greater than 60%, when compared with their precursor obacunone and toosendanin (a positive control). To C7-oxime alkylester series, the proper length of their side chain at the C-7 position of C7-oximeobacunone to the insecticidal activity was very important; to C7-oxime arylester series, introduction of the chlorine atom on the phenyl ring at the C-7 position of C7-oximeobacunone could lead to the best potent compounds. According to the QSAR model, five descriptors such as RDF100v, RDF105u, Dm, Mor15m and R1u, were likely to affect the biological activity of these compounds. Among them, the most important one was RDF100v. The correlation coefficient (R2), the cross-validation correlation coefficient (Q2) and the standard deviation error in prediction (SDEP) are 0.891, 0.835 and 0.0358, respectively.
    RSC Advances 01/2015; 5(40):31700-31707. DOI:10.1039/C5RA01411E · 3.84 Impact Factor
  • Xiang Yu · Guodong Ding · Xiaoyan Zhi · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: Here we have prepared a series of ester compounds of obacunone, a naturally occurring limonoid, isolated from plants such as Citrus and Dictamnus angustifolius. Their insecticidal activity was evaluated at 1mg/mL against the pre-third-instar larvae of oriental armyworm (Mythimna separata Walker), a typical lepidopteran pest. When obacunone reacted with NaBH4, the ratio of two reduction products, C7α-hydroxyobacunone (2) and C7β-hydroxyobacunone (3), was related to the reaction mixing solvents. C7α-Propionyloxybacunone (4b) and C7β-(n)heptanoyloxybacunone (5g) exhibited the more promising insecticidal activity than their precursor obacunone and toosendanin. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Bioorganic & Medicinal Chemistry Letters 11/2014; 25(1):25-29. DOI:10.1016/j.bmcl.2014.11.027 · 2.33 Impact Factor
  • Xiaoyan Zhi · Chun Yang · Xiang Yu · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: To discover new natural-product-based insecticidal agents, a series of novel oxime derivatives of podophyllotoxin-based phenazines modified in the C, D and E rings of podophyllotoxin were prepared and tested as insecticidal agents against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at 1 mg/mL. The steric configuration of IIIc was unambiguously confirmed by single-crystal X-ray diffraction analysis. Compounds IIIa–d, and IIIi exhibited an equal or higher insecticidal activity than toosendanin.
    Bioorganic & Medicinal Chemistry Letters 11/2014; 24(24). DOI:10.1016/j.bmcl.2014.10.081 · 2.33 Impact Factor
  • Yuanyuan Yan · Rui Zhang · Xiang Yu · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: Based on specific reactivity of the vinyloxy group to Hg2+ ions, a new ratiometric phenanthroimidazole-based fluorescent sensor, 2-(2-(vinyloxy)phenyl)-1 H-phenanthro[9,10-d]imidazole, is prepared. The selectivity of the probe toward Hg2+ ions is very high, and shows minimal interference from other commonly coexistent metal ions. The reactive stoichiometry of the probe with Hg2+ ion is 2:1. Its detection limit is evaluated and Hg2+ ions can be detected down to a lower limit of 2.5×10−8 M. Moreover, the Hg2+-promoted selective hydrolysis of a vinyloxy group of the probe is further confirmed by 1H NMR spectroscopy and mass spectrometry.
    ChemPlusChem 10/2014; DOI:10.1002/cplu.201402266 · 3.24 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Using a modified Walden plot analysis, we demonstrate that polyether-based solid electrolytes have intrinsic limitations for ionic transport at ambient and low temperatures, due to strongly coupled segmental and ion dynamics. On the other hand, rigid polymers can exhibit ionic conductivity that is highly decoupled from segmental relaxation, thus providing a significant advantage over traditional polyether electrolytes. Our analysis emphasizes that decoupling of ionic transport from segmental dynamics is the key for macromolecular design of “superionic” polymers.
    Solid State Ionics 09/2014; 262:782-784. DOI:10.1016/j.ssi.2013.09.026 · 2.11 Impact Factor
  • Juanjuan Wang · Xiang Yu · Xiaoyan Zhi · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: In continuation of our program aimed at the discovery of new natural-product-based insecticidal agents, twenty-six deoxypodophyllotoxin derivatives modified in the D-ring were synthesized and evaluated as insecticidal agents against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at 1mg/mL. The configuration of three compounds 3, 4, and IIIi was unambiguously determined by single-crystal X-ray diffraction. It demonstrated that aminolysis of deoxypodophyllotoxin in the presence of pyrrolidine and piperidine could result in complete inversion of the configuration of the carbonyl group at its C-2 position. Five compounds IIa, IIi-k, and IIIh showed the equal or higher insecticidal activity than toosendanin. Especially IIj displayed the most potent insecticidal activity with the final mortality rate of 65.5%.
    Bioorganic & Medicinal Chemistry Letters 08/2014; 24(18). DOI:10.1016/j.bmcl.2014.07.076 · 2.33 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Replacing traditional liquid electrolytes by polymers will significantly improve electrical energy storage technologies. Despite significant advantages for applications in electrochemical devices, the use of solid polymer electrolytes is strongly limited by their poor ionic conductivity. The classical theory predicts that the ionic transport is dictated by the segmental motion of the polymer matrix. As a result, the low mobility of polymer segments is often regarded as the limiting factor for development of polymers with sufficiently high ionic conductivity. Here, we show that the ionic conductivity in many polymers can be strongly decoupled from their segmental dynamics, in terms of both temperature dependence and relative transport rate. Based on this principle, we developed several polymers with "superionic" conductivity. The observed fast ion transport suggests a fundamental difference between the ionic transport mechanisms in polymers and small molecules and provides a new paradigm for design of highly conductive polymer electrolytes.
    Polymer 08/2014; 55(16). DOI:10.1016/j.polymer.2014.06.085 · 3.77 Impact Factor
  • Yi Wang · Xiang Yu · Xiaoyan Zhi · Xiao Xiao · Chun Yang · Hui Xu
    Bioorganic & medicinal chemistry letters 06/2014; 24(12):2621–2624. · 2.33 Impact Factor
  • Yi Wang · Xiang Yu · Xiaoyan Zhi · Xiao Xiao · Chun Yang · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, a series of novel hydrazone derivatives of podophyllotoxin, which is a naturally occurring aryltetralin lignan and isolated as the main secondary metabolite from the roots and rhizomes of Podophyllum species, were synthesized and evaluated as insecticidal agents against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at 1mg/mL. Especially compounds 8i, 8j, 8t, and 8u showed the more potent insecticidal activity with the final mortality rates greater than 60%.
    Bioorganic & medicinal chemistry letters 04/2014; 24(12). DOI:10.1016/j.bmcl.2014.04.074 · 2.33 Impact Factor
  • Lingling Fan · Yong Guo · Xiaoyan Zhi · Xiang Yu · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: As part of our ongoing efforts to discover new natural-product-based insecticidal agents, in the present study, an efficient method for the stereoselective α-chlorination at the C-2 position of 2'(2',6')-(di)halogenopodophyllotoxin derivatives was firstly developed. Subsequently, a series of novel esters of 2α-chloro-2'(2',6')-(di)halogenopicropodophyllotoxin with modified C, D and E rings of podophyllotoxin were smoothly obtained. Finally, all the title compounds were tested against the pre-third-instar larvae of oriental armyworm (Mythimna separate Walker) at 1 mg/mL. It was found that besides their 2'-halogen-substituted E-ring, the stereoselective α-chlorination at the C-2 position of 2'(2',6')-(di)halogenopodophyllotoxins was also related to the chlorination reagents. Especially 2α-chloro-4α-(benzoyl)oxy-2'-chloropicropodophyllotoxin (6e) and 2α-chloro-4α-(2-chlorophenylacyl)oxy-2'-bromopicropodophyllotoxin (8f) showed the most potent insecticidal activity with the final mortality rates greater than 60%. For 4α-(alkylacyl)oxy derivatives of 2α-chloro-2'(2',6')-(di)halogenopicropodophyllotoxin, the effect of the length of their side chain at the C-4 position of podophyllotoxin skeleton on the insecticidal activity was not very obvious; For 4α-(arylacyl)oxy derivatives of 2α-chloro-2'-chloro/bromopicropodophyllotoxin, the electronic effect of the substituents on their phenyl ring at the C-4 position of podophyllotoxin skeleton on the insecticidal activity was observed.
    Journal of Agricultural and Food Chemistry 04/2014; 62(17). DOI:10.1021/jf405316w · 3.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To discover the new natural-product-based insecticidal agents, four series of sixty novel 4β-acyloxypodophyllotoxin analogs modified in the C and E rings were prepared, and their insecticidal activity was tested against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at the concentration of 1mg/mL. It demonstrated that the position of the dioxo group on the E-ring of 4'-demethylepipodophyllotoxin was regioselectively controlled by the chlorine atom at its C-2' position when 2'-chloro-4'-demethylepipodophyllotoxin was oxidized by sodium periodate. Among all the derivatives, IIIi exhibited the best potent insecticidal activity with the final mortality rate of 63.3%. To alkylacyloxy series, the proper length of the side chain at the C-4 position of Ia-g, IIa-g and IIIa-g was important for their insecticidal activity.
    Bioorganic & medicinal chemistry letters 01/2014; 24(3). DOI:10.1016/j.bmcl.2013.12.105 · 2.33 Impact Factor
  • Yong Guo · Huan Qu · Xiaoyan Zhi · Xiang Yu · Chun Yang · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: Herein we prepared a series of novel fraxinellone derivatives modified at the C-1 or C-8 position in its B ring as insecticidal agents against the pre-third-instar larvae of oriental armyworm, Mythimna separata Walker at 1 mg/mL. Five key steric configurations of compounds 2, 3, 8f, 8g, and 8j were further determined by single-crystal X-ray diffraction. It was found that the kinds and the amount of the reduction products of fraxinellone were related to the molar ratio between the reduction agent Red-Al® and the substrate fraxinellone. Among all the derivatives, compounds 2, 8i, 8j and 8o displayed the more promising insecticidal activity than their precursor fraxinellone and toosendanin. The preliminary structure-activity relationships revealed that the lactone (B-ring) of fraxinellone contributed to the observed insecticidal activity; the double bond at the C-2 position of fraxinellone was not necessary for the insecticidal activity; conversion of the oxygen atom of carbonyl group on the lactone of fraxinellone to the sulfur one can not improve the insecticidal activity; introduction of the electron-withdrawing groups on the phenyl ring of 8f, to benzoyloxy series, could result in the more potent compounds.
    Journal of Agricultural and Food Chemistry 11/2013; 61(49). DOI:10.1021/jf404195m · 3.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A chemically diverse library of benzimidazole-azo-phenol derivatives was efficiently prepared and screened for their antifungal activities against five phytopathogenic fungi. Some compounds exhibited the potent antifungal activities. As compared with a commercially available agricultural fungicide, hymexazol, especially compound V-5 showed the most promising broad-spectrum antifungal activities against five phytopathogenic fungi. The EC50 values of V-5 against F. graminearum, A. solani, V. mali, B. cinerea, and C. lunata were 0.09, 0.08, 0.06, 0.07, and 0.11 μmol/mL, respectively.
    Combinatorial chemistry & high throughput screening 10/2013; DOI:10.2174/13862073113166660058 · 1.93 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Well-defined conjugated polymers in confined geometries are challenging to synthesize and characterize, yet they are potentially useful in a broad range of organic optoelectronic devices such as transistors, light emitting diodes, solar cells, sensors, and nanocircuits. Herein we report a systematic study of optoelectrical properties, grafting density effects, and nanopatterning of a model, end-tethered conjugated polymer system. Specifically, poly(para-phenylene) (PPP) brushes of various grafting density are created in situ by aromatizing well-defined, end-tethered poly(1,3-cyclohexadiene) (PCHD) “precursor brushes”. This novel precursor brush approach provides a convenient way to make and systematically control the grafting density of high molecular weight conjugated polymer brushes that would otherwise be insoluble. This allows us to examine how grafting density impacts the effective conjugation length of the conjugated PPP brushes and to adapt the fabrication method to develop spatially patterned conjugated brush systems, which is important for practical applications of conjugated polymer brushes.
    10/2013; 1(43). DOI:10.1039/C3TA12745A
  • Huan Qu · Xiang Yu · Xiaoyan Zhi · Min Lv · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, twenty-six new piperine-based hydrazone derivatives were synthesized from piperine, an alkaloid isolated from Piper nigrum Linn. The single-crystal structures of 6c, 6q and 6w were unambiguously confirmed by X-ray crystallography. Their insecticidal activity was evaluated against the pre-third-instar larvae of Mythimna separata Walker in vivo. Especially compounds 6b, 6i and 6r, the final mortality rates of which, at the concentration of 1mg/mL, were 62.1%, 65.5% and 65.5%, respectively, exhibited more pronounced insecticidal activity compared to toosendanin at 1mg/mL, a commercial botanical insecticide isolated from Melia azedarach. It suggested that introduction of the substituents at the C-2 position on the phenyl ring of the hydrazone derivatives was important for their insecticidal activity.
    Bioorganic & medicinal chemistry letters 08/2013; 23(20). DOI:10.1016/j.bmcl.2013.08.053 · 2.33 Impact Factor
  • Zhiping Che · Xiang Yu · Lingling Fan · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: Unexpected sequential E-ring dihalogenation of podophyllotoxin analogues is reported. It demonstrated that a chlorine/bromine atom was prior introduced at the C2' position of podophyllotoxin, and the corresponding free rotation of E-ring around the C1-C1' bond of 2'-chloro or 2'-bromopodophyllotoxin was restricted. When 2'-chloro or 2'-bromopodophyllotoxin reacted with N-chlorosuccinimide (NCS), the chlorine atom was regioselectively introduced at their C6' position on the E-ring. Whereas 2'-chloro or 2'-bromopodophyllotoxin reacted with NBS, the bromine atom was regioselectively introduced at their C5 position on the B-ring. When 2'-chloropodophyllotoxin reacted with different carboxylic acids in the presence of BF3·Et2O, the steric effect of its E-ring for stereoselective synthesis of 4β-acyloxy-2'-chloropodophyllotoxin derivatives was observed. The insecticidal activity of 2'(2',6')-(di)halogen-substituted podophyllotoxin derivatives were evaluated with Mythimna separata Walker.
    Bioorganic & medicinal chemistry letters 08/2013; 23(20). DOI:10.1016/j.bmcl.2013.08.044 · 2.33 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In continuation of our program aimed at the discovery and development of natural -product-based insecticidal agents, we have prepared three series of novel 4α-acyloxy-2'(2',6')-(di)halogenopodophyllotoxin derivatives modified in the C and E rings of podophyllotoxin, which is a naturally occurring aryltetralin lignan isolated from the roots and rhizomes of Podophyllum hexandrum. Their structures were well characterized by 1H NMR, HRMS, ESI-MS, optical rotation and mp. The stereochemical configurations of compounds 5s, 6b, 6d, and 7q were unambiguously confirmed by single-crystal X-ray diffraction. Their insecticidal activity was evaluated against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at a concentration of 1 mg/mL. Among all the derivatives, especially compounds 5a, 5n, 7f, 7n and 7w exhibited the most potent insecticidal activity with the final mortality rates of 70% or so. It suggested that a chlorine or bromine atom introduced at the C2' or C2' and C6' position on the E-ring of podophyllotoxin was necessary for obtaining the potent compounds. It will pave the way for further design, structural modification and development of podophyllotoxin derivatives as insecticidal agents.
    Journal of Agricultural and Food Chemistry 08/2013; 61(34). DOI:10.1021/jf4025079 · 3.11 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, four series of novel cholesterol-based hydrazone derivatives were synthesized, and their insecticidal activity was tested against the pre-third-instar larvae of oriental armyworm, Mythimna separata (Walker) in vivo at 1mg/mL. All the derivatives showed the better insecticidal activity than their precursor cholesterol. Quantitative structure-activity relationship (QSAR) model demonstrated that six descriptors such as RDF085v, Mor06u, Mor11u, Dv, HATS0v and H-046, are likely to influence the insecticidal activity of these compounds. Among them, two important ones are the Mor06u and RDF085v.
    Bioorganic & medicinal chemistry letters 07/2013; 23(17). DOI:10.1016/j.bmcl.2013.06.099 · 2.33 Impact Factor
  • Juan Juan Wang · Xiaoyan Zhi · Xiang Yu · Hui Xu
    [Show abstract] [Hide abstract]
    ABSTRACT: In continuation of our program aimed at the discovery and development of natural-product-based insecticidal agents, a series of new deoxypodophyllotoxin-based phenazine analogs modified in its E-ring were prepared, and their structures were well characterized by 1H NMR, HRMS, ESI-MS, IR, optical rotation and mp. The absolute steric configuration of one key isomer was unambiguously confirmed by X-ray crystallography. Their insecticidal activity was examined against the pre-third-instar larvae of Mythimna separate Walker in vivo at the concentration of 1 mg/mL. All derivatives showed delayed insecticidal activity. Especially compound 9i, containing p-methoxybenzoylamnio at the C-9' position of deoxypodophyllotoxin-based phenazine fragment, exhibited the most promising insecticidal activity with the final mortality rate of 72.4%. According to the symptoms of the tested M. separate, the derivatives likely displayed the anti-molting hormone effect. In addition, preliminary structure-activity relationships were observed. It suggested that the proper length of the side chain of alkylacylamino might be important for their insecticidal activity, and introduction of the acylamino groups at the C-9' position of deoxypodophyllotoxin-based phenazine fragment usually afforded the more potent compounds than those containing the same ones at the C-10' position. It will pave the way for further design, structural modification and development of deoxypodophyllotoxin-based derivatives as insecticidal agents.
    Journal of Agricultural and Food Chemistry 06/2013; 61(26). DOI:10.1021/jf4011033 · 3.11 Impact Factor