Long Li

Jiangsu University of Science and Technology, Chenkiang, Jiangsu Sheng, China

Are you Long Li?

Claim your profile

Publications (11)21.2 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Flos Lonicerae (FL) was widely planted in China as a kind of pharmaceutical resource. In our research, the variations in content and antioxidant activity of essential oil of FL from five different sites of China were investigated. The results revealed that the essential oil content of samples varied over the range of 0.288 ± 0.015% to 0.387 ± 0.016%. The essential oil antioxidant activity of samples were also determined by scavenging activity against 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid ammonium salt) (ABTS), ferric reducing/antioxidant power (FRAP) test and β-carotene-linoleic acid bleaching test. The results indicated that the sample from Shaoyang showed better antioxidant activity than the others. And the β-carotene-linoleic acid bleaching activity could reach 92.31%, when the concentration of the sample from Shaoyang was 4 mg/mL, indicating that the sample from Shaoyang possessed excellent antioxidant activity. The chemical compositions of the essential oil were finally identified by GC-MS, and more than 20 compounds were identified. Principal component analysis was also performed to investigate the difference of the essential oil samples.
    No preview · Article · Dec 2015 · Industrial Crops and Products
  • [Show abstract] [Hide abstract]
    ABSTRACT: A Box-Behnken design (BBD) was applied to optimize the ultrasound-assisted extraction of polysaccharides from mulberry leaves. Under the optimum conditions of an extraction temperature of 57 °C, an extraction time of 80 min and a liquid/solid ratio of 53 mL/g, the mulberry leaf polysaccharide (MLP) yield was 6.92 ± 0.29%. Then, three fractions of MLPs were obtained by deproteinization, dialysis and decolorization. The carbohydrate content, FT-IR spectrum and monosaccharide composition of the MLPs were also investigated. The antioxidant activities of the three fractions were compared, and the results indicated that the antioxidant activities decreased with the increasing MLP purity. Therefore, highly concentrated MLPs were shown to have very little antioxidant activity. After quercetin (10 μg/mL) was added, the antioxidant activities were improved significantly. This result showed that MLPs and quercetin have a synergistic effect on the antioxidant activity. Although the MLPs have very little antioxidant activity alone, they greatly enhance the antioxidant activity of flavonoids. Thus, MLPs can be used as an antioxidant activity enhancer in the food industry.
    No preview · Article · Nov 2015 · Carbohydrate Polymers
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new method based on a Direct Analysis in Real Time (DART) ionization source coupled with triple quadrupole tandem mass spectrometry has been developed for rapid qualitative and quantitative analyses of 1-deoxynojirimycin (DNJ) in mulberry leaves. Two ions produced from DNJ, [M+H](+) (m/z 164) and [M-2H+H](+) (m/z 162), are observed using DART-MS in the positive ion mode. The peak areas of the two selected ions monitoring (SIM) signals of ([M+H](+) (m/z 164) and [M-2H+H](+) (m/z 162)) are integrated to determine the peak area for quantitative analyses. A reasonable linear regression equation is obtained in the range of 1.01 to 40.50μg/mL, with a linear coefficient (R(2)) of 0.996. The limits of detection (LOD) and quantification (LOQ) of the method are 0.25 and 0.80μg/mL, respectively. The range of recovery is shown to be 87.73-95.61%. The results derived from the developed DART-MS method are in good agreement with those from the conventional HPLC-FLD method. By contrast, DART-MS in SIM mode is a simple, rapid and high-throughput approach for the determination of the DNJ content in mulberry leaves. The present method is advantageous for the rapid screening of mulberry leaves containing high DNJ contents. Copyright © 2015 Elsevier B.V. All rights reserved.
    No preview · Article · Oct 2015 · Journal of pharmaceutical and biomedical analysis
  • Zeyu Liu · Xiufen Yan · Long Li · Guohua Wu
    [Show abstract] [Hide abstract]
    ABSTRACT: The static first hyperpolarizabilities (β0) of several free-based and metal-doped rosarins were extracted from density functional theory (DFT) calculations. The calculated β0 value of the upward opening calix[n]pyrrole is almost 4.5 times larger than that of the downward one profiting from the greater separation of charge. Doping an alkali atom into the free-based rosarin can obtain a cation-anion separation molecule with enormous hyperpolarizability. The electride Cs@calix[6]pyrroles have considerably large β0 values with 31 002 and 82 647 a.u. for upward and downward opening configurations, while the β0 values of the related calix[6]pyrroles are only 784 and 3532 a.u., respectively.
    No preview · Article · Oct 2015 · Chemical Physics Letters
  • Zeyu Liu · Xiufen Yan · Long Li · Guohua Wu
    [Show abstract] [Hide abstract]
    ABSTRACT: The optical properties of two series of azobenzene derivatives were modulated by backbone modifications with the density functional theory (DFT) calculations. Compared to the short-chain molecule, the chromophore with an elongated π-bridge exhibits a greater extent of charge transfer during one-photon excitation and hence possesses a larger molecular first hyperpolarizability (β0). Meanwhile, an evident red-shift in the maximum absorption was observed after extension of the π-conjugated backbone. The tendency of the static β 0 value derived from the two-state model is consistent with the result of the calculation at M06-2X/6-311++G(d,p) level by means of analytical derivative method. The dynamic perturbations were revealed to cause the obvious enhancement of the first hyperpolarizability. The more closer the foundational wavelength to two times the value of the maximum absorption in one-photon transition, the larger βRHS value is observed for the chromophore. The nonlinear optical (NLO) properties augment with the introduction of the THF solvents by comparing the gas-phase values. With increasing the length of conjugated bridge, the dynamic βRHS value increases more rapidly in THF solution than in vacuum.
    No preview · Article · Jul 2015 · Journal of Theoretical and Computational Chemistry
  • [Show abstract] [Hide abstract]
    ABSTRACT: As the most important food plant for sericultural industry, mulberry trees have to suffer from a wide range of abiotic and biotic stresses, such as drought and high salinity. MicroRNAs (miRNAs) have been proved to play important roles in abiotic stresses regulation in many plants. However, there are seldom reports on the miRNAs expression profiles upon abiotic challenges in mulberry. In this study, three small RNA libraries from mulberry leaf tissue with or without drought or salt treatment were constructed and deep sequenced. Total of 48 conserved miRNAs (including miRNA*) and 162 novel miRNAs were identified (processing precision value>0.1). A total of 270 and 1963 target genes were predicted for conserved miRNAs and novel miRNAs, respectively. 13 differentially expressed miRNAs were detected under drought or salt stresses by deep sequencing and qRT-PCR. 5' RLM-RACE validated Morus 013341 to be the target gene of miR-395a. Our results provided initial clue to further study molecular mechanism on abiotic stresses regulation in mulberry. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
    No preview · Article · Jul 2015 · Plant Physiology and Biochemistry
  • [Show abstract] [Hide abstract]
    ABSTRACT: Methionine sulfoxide reductase plays a regulatory role in plant growth and development, especially in scavenging reactive oxygen species by restoration of the oxidation of methionine in protein. A fulllength cDNA sequence encoding methionine sulfoxide reductase (MSR) from mulberry, which we designated MMSR, was cloned based on mulberry expressed sequence tags (ESTs). Sequence analysis showed that the MMSR is 810 bp long, encoding 194 amino acids with a predicted molecular weight of 21.6 kDa and an isoelectric point of 6.78. The expression level of the MMSR gene under conditions of drought and salt stresses was quantified by qRT-PCR. The results show that the expression level changed significantly under the stress conditions compared to the normal growth environment. It helps us to get a better understanding of the molecular basis for signal transduction mechanisms underlying the stress response in mulberry.
    No preview · Article · Sep 2013 · Russian Journal of Bioorganic Chemistry
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) is one of the most important pathogens of silkworm. MicroRNAs (miRNAs) have been demonstrated to play key roles in regulating host-pathogen interaction. However, there are limited reports on the miRNAs expression profiles during insect pathogen challenges. In this study, four small RNA libraries from BmCPV-infected midgut of silkworm at 72 h post-inoculation and 96 h post-inoculation and their corresponding control midguts were constructed and deep sequenced. A total of 316 known miRNAs (including miRNA*) and 90 novel miRNAs were identified. Fifty-eight miRNAs displayed significant differential expression between the infected and normal midgut (P value < = 0.01 and fold change > = 2.0 or < = 0.5), among which ten differentially expressed miRNA were validated by qRT-PCR method. Further bioinformatics analysis of predicted target genes of differentially expressed miRNAs showed that the miRNA targets were involved in stimulus and immune system process in silkworm.
    Preview · Article · Jul 2013 · PLoS ONE
  • Ping Wu · He-Ying Qian · Xi-Jie Guo · Long Li · Tao Chen
    [Show abstract] [Hide abstract]
    ABSTRACT: A pair of specific primers were designed according to the published 118 bp conserved sequence of polyhedrin gene of Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) in GenBank and a serial dilutions of a recombinant plasmid were prepared and used to generate standard curves, to establish a real-time fluorescent quantitative PCR method for detection of BmCPV. The results showed that the linear relationship between virus concentration (X) and Ct (Y) was Y = -3. 582 lgX + 38.748 with the correlation coefficient R2 = 0999. The method was very sensitive, specific and reproducible. It can be applied in the rapid detection of BmCPV and the prevalence investigation of this disease.
    No preview · Article · Apr 2013 · Bing du xue bao = Chinese journal of virology / [bian ji, Bing du xue bao bian ji wei yuan hui]
  • [Show abstract] [Hide abstract]
    ABSTRACT: A full-length cDNA sequence encoding polygalacturonase-inhibiting protein (PGIP) from mulberry, which we designated MPGIP (GenBank accession no.: HM044383), was cloned based on mulberry expressed sequence tags (ESTs). Sequence analysis showed that the MPGIP is 1,274 base pairs (bp) in length, encoding 333 amino acids with a predicted molecular weight of 37.29 kDa and an isoelectric point of 7.25. The expression levels of MPGIP at different developmental stages in mulberry leaves and flowers and in different tissues were investigated. The results showed that MPGIP transcripts were most abundantly expressed in the young leaf, and the expression level of the mRNA could be increased significantly under salicylic acid (SA), abscissic acid (ABA), and NaCl stress conditions compared to the normal growth environment. And we also expressed the recombinant protein. This is to help understand a molecular basis for signal transduction mechanism underlying the stress response in mulberry.
    No preview · Article · Feb 2012 · Plant Molecular Biology Reporter
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A full-length cDNA sequence encoding CaM from mulberry, which we designated MCaM-3 (GenBank accession No: GQ303247), was cloned based on mulberry expressed sequence tags(ESTs). Sequence analysis showed that MCaM-3 is 951 base pairs in length, encoding 149 amino acids with a predicted molecular weight of 16.85 kD and an isoelectric point of 3.95. Online SMART analysis showed that the MCaM-3 protein has four EFh functional domains, which can bind calcium. The expression level of MCaM-3at different developmental stages in mulberry leaves and flowers and in different tissues was investigated. The results showed that MCaM-3 transcripts are most abundantly expressed in mature tissues, such as mature female flowers and climax leaves, and the expression level of the mRNA could be increased significantly under low temperature, drought, and salt stress conditions compared to the normal growth environment. This research will help us understand the resistance mechanism of functional genes in mulberry. Keywords Morus L. MCaM-3 gene–Molecular cloning–Gene expression
    Full-text · Article · Apr 2011 · Genes & genomics