Publications by authors named "Jianbei Li"

Background: For microorganisms on a paper surface, the lack of water is one of the most important stress factors. A strain of Bacillus megaterium FDU301 was isolated from plaques on a paper surface using culture medium with polyethylene glycol 200 (PEG200) to simulate an arid condition. Global transcriptomic analysis of B.

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is a conserved miRNA highly expressed in insects. We previously showed that the antisense inhibitor (antagomiR) of improved the infection by baculovirus Autographa californica nucleopolyhedrovirus (AcMNPV) in and larvae. Here, we constructed a recombinant AcMNPV (vPH-banS) expressing sponge, an mRNA containing eight antisense binding sites for .

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Frankincense resins are extensively used as natural remedies in regions ranging from North Africa to China. Triterpenoid metabolites from frankincense exhibit notable anti-inflammatory and anti-tumor properties. In the present paper, without the use of an isolation process, the fragmentation rules and NMR spectral characteristics of triterpenoid metabolites in frankincense are summarized through a coupling method using high performance liquid chromatography-diode array detection/electrospray ionization tandem mass spectrometry (HPLC-DAD/ESI-MS(n)) combined with HPLC-nuclear magnetic resonance (NMR) experiments.

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Hydroxysafflor yellow A (HSYA) is the main active component of the Chinese herb Carthamus tinctorius L.. Purified HSYA is used as a neuroprotective agent to prevent cerebral ischemia.

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Cardiac glycosides are a class of naturally occurring compounds that are characterized by some interesting biological activities and are widely distributed in the plant kingdom and can also be found in some animals. There is an interest in the chemical characterization of these molecules due to their toxicity and their use in medicines. In the study reported here, a combination of electrospray ionization tandem mass spectrometry with high-performance liquid chromatography equipped with diode-array detector (HPLC-DAD/ESI-MS(n)), and hyphenation to both liquid chromatography and nuclear magnetic resonance spectroscopy (HPLC/NMR) were utilized for the on-line analyses of cardiac glycosides from Periploca forrestii.

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The mass fragmentation patterns of stilbene glycosides isolated from the genus Lysidice were investigated by negative ion electrospray ionization tandem mass spectrometry, and the influence of collision energy on their fragmentation behavior is discussed. It is found that the presence of the Y(0)(-) and B(0)(-) ions in the MS(2) spectra is characteristic for 1-->6 linked diglycosyl stilbenes, while the Y(0)(-), Y(1)(-), and Z(1)(-) ions are representative ions of 1-->2 linked diglycosyl stilbenes. These results indicate that ESI-MS(n) in the negative ion mode can be used to differentiate 1-->6 and 1-->2 linked diglycosyl stilbenes.

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The MS fragmentation behavior of the C-21 steroidal glycosides from Dregea sinensis var. corrugata was investigated by positive and negative ion electrospray ionization MS using a multistage tandem mass spectrometer equipped with an ion trap analyzer. The mass fragmentation patterns of steroidal glycosides substituted with an orthoacetate group were summarized, and the fragmentation patterns were applied to the online structure identification of the steroidal glycosides in the extract.

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Triterpenoid saponins are the major bioactive constituents of Panax notoginseng. In the study reported here, the fragmentation behavior of triterpenoid saponins from P. notoginseng was investigated by electrospray ionization tandem mass spectrometry (ESI-MS(n))and high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC/ESI-MS(n)).

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An efficient procedure based on biological and chemical screening has been performed to investigate the antioxidant constituents of the bark of Lysidice brevicalyx Wei. The procedure allowed the rapid identification of known compounds and tentative characterization of unknown compounds by online LC/UV/ESIMS(n) analyses of the antioxidant fraction. Targeted isolation of the unknown compounds has led to the discovery of seven new stilbene glycosides, named lysidisides L-R (1-7), together with a known stilbene glycoside, (E)-resveratrol 3-O-rutinoside (8).

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The fragmentation behaviors of the two types of modified pregnane glycosides from Cynanchum forrestii were investigated by positive ion electrospray ionization multi-stage tandem mass spectrometry equipped with an ion trap analyzer. The spectral data further illuminated the predominance of ESI-MS(n) technique on the identification of pregnane glycosides, especially of two sorts of modified pregnane glycosides with aglycone skeletons of 13,14:14,15-disecopregnane-type and 14,15-secopregnane-type, which differed in the presence of the characteristic [M-46+Na]+ ion. For sugar residues, the fragment ions were analyzed and some possible fragmentation pathways were proposed, especially for 3-demethyl-2-deoxythevetose, the glycosidic cleavage reaction was easier to occur than those of other sugar units in its moiety.

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A combination of electrospray ionization tandem mass spectrometry with high-performance liquid chromatography (HPLC/ESI-MSn), and hyphenation of liquid chromatography to nuclear magnetic resonance spectroscopy (HPLC/NMR), have been extensively utilized for on-line analysis of natural products, analyzing metabolite and drug impurity. In our last paper, we reported an on-line analytical method for structural identification of trace alkaloids in the same class. However, the structural types of the constituents in plants were various, such as flavanoids, terpenoids and steroids.

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Three new dibenz[b,f]oxepins: 6-methoxy-7-methyl-8-hydroxydibenz[b, f]oxepin (1), 1,8-dimethoxy-6-hydroxy-7-methyldibenz[b, f]oxepin (2), and 1-hydroxy-6,8-dimethoxy-7-methyldibenz[b,f]oxepin (3), along with two known dibenz[b,f]oxepins pacharin (4) and bauhiniastatin 4 (5), were isolated from Cercis chinensis Bunge (Leguminosae). Their structures were elucidated on the basis of spectroscopic evidence (EI-MS, UV, IR, (1)H, (13)C and 2D NMR). Compounds 1-5 were isolated from the Cercis genus for the first time.

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Objective: To study the chemical constituents in the root of Isatis indigotica.

Method: The constituents root were separated through various chromatographic techniques and their structures were elucidated by means of physicochemical properties and the analysis of their spectral data.

Result: Eleven compounds were isolated and identified as (+) -isolariciresinol (1), lariciresinol (2), lariciresinol-9-O-beta-D-glucopyranoside (3), lariciresinol-4'-O-beta-D-glucopyranoside (4), lariciresinol-4,4'-bis-O-beta-D-glucopyranoside (5), 3-formylindole (6), 1-methoxy-3-indolecarbaldehyde (7), 1-methoxy-3-indoleacetonitrile (8), deoxyvasicinone (9), epigoitrin (10), adenosine (11).

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Electrospray ionization multi-stage tandem mass spectrometry (ESI-MSn), and combination with HPLC (HPLC/ESI-MSn), have been extensively applied to on-line analysis of natural products. Hyphenation of liquid chromatography to nuclear magnetic resonance spectroscopy (HPLC/NMR) has been developed in the last decade, which is utilized for the analysis of metabolites and drug impurities. In the study reported here, the fragmentation behaviors of eight cassaine-type diterpenoid amides from Erythrophleum fordii were investigated by ESI-MSn.

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The analgesic and anti-inflammatory activities of a salicylate derivatives fraction (SDF) isolated from Gaultheria yunnanensis (FRANCH.) REHDER and the mechanisms of actions were investigated in the present study. The major constituent of SDF, which represented around 50% of this fraction, was a methyl salicylate diglycoside named gaultherin.

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Six new sesquiterpene glycosides, compounds 1-6, with eudesmanolide, elemanolide, lindenane, and germacranolide sesquiterpene aglycons, along with one known compound, chloranoside A (7), have been isolated from the whole plant of Sarcandra glabra. The structures of 1-6 were elucidated by chemical and spectroscopic methods including (1)H-(1)H COSY, HMQC, HMBC, and NOESY NMR experiments. In addition, compounds 1-7 showed pronounced hepatoprotective activities against D-galactosamine-induced toxicity in WB-F344 rat hepatic epithelial stem-like cells.

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Two new type dicoumarins (dicoumaro-p-menthanes), named dibothrioclinins I (1) and II (2) were isolated from the roots and rhizomes of Gerbera piloselloides (L.) CASS., collected in Yunnan Province, China.

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Dibothrioclinin I and II, namely (+)-(11R,12S,25R,27S)- and (+/-)-(11RS,12RS,25RS,27SR)-3,3,7,17,21-pentamethyl-4,12,18,26-tetraoxaheptacyclo[15.11.1.

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Objective: To study the chemical constituents from the roots and rhizomes of Gerbera piloselloides.

Method: The compounds were isolated by silica gel column chromatography, and their structures were elucidated by means of spectral analysis.

Result: Seven compounds were identified as bothrioclinin (I), hydroquinone (II), marmesin (III), succinic acid (IV), umbelliferone (V), isoarborinol (VI) and beta-sitosterol (VII).

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