Publications by authors named "Da-wei Tan"

Background: Although progress has been made in managing cholesterol, targeting inflammation is essential for further reducing cardiovascular risk, as CVDs remain the leading cause of death globally. This study aimed to explore the association between plasma ceramide levels and residual inflammatory risk in patients with CAD.

Methods: A cross-sectional observational design was adopted using data from a secondary analysis of a multicenter prospective cohort study in China.

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This study aims to evaluate the clinical application value of two materials, drug-eluting stent, and biodegradable stent, in the treatment of coronary heart disease. The results show that the therapeutic effects of drug-eluting stents and biodegradable stents are similar. Both treatment methods have high safety and effectiveness.

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One hexanuclear Cu(I) cluster of 4,6-dimethylpyrimidine-2-thiolate efficiently catalyzes the dehydrogenative cross-coupling of secondary and primary alcohols to α-alkylated ketones with high selectivity. This transformation proceeds through a one-pot sequence of dehydrogenation of alcohols, condensation of aldehydes and ketones, hydrogenation of the resulting α,β-unsaturated ketones, and dehydrogenation of the α-alkylated alcohols to generate α-alkylated ketones. This catalytic system also displays high activity for the annulation reaction of secondary alcohols with γ-amino- and 2-aminobenzyl alcohols to yield pyridines and quinolines, respectively.

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Unsaturated alcohols and saturated carbonyls are important chemical, pharmaceutical, and biochemical intermediates. We herein report an efficient transfer hydrogenation protocol in which conversion of unsaturated carbonyl compounds to either unsaturated alcohols or saturated carbonyls was catalyzed by Cu(I) N-donor thiolate clusters along with changing hydrogen source (isopropanol or butanol) and base (NaOH or KCO). Mechanistic studies supported by DFT transition state modeling indicate that such a chemoselectivity can be explained by the relative concentrations of Cu(I) monohydride and protonated Cu(I) hydride complexes in each catalytic system.

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Reactions of a pincer ligand 2-(1H-pyrazol-1-yl)-6-(1H-pyrazol-3-yl)pyridine (pzpypzH) with Cu(NO3)2, Cu(ClO4)2, CuSO4, CuCl2 or CuI produced three dinuclear Cu(ii) complexes [{Cu(NO3)}(μ-pzpypz)]2 (1), [{Cu(ClO4)}(μ-pzpypz)]2 (2), [Cu2(μ-SO4)(μ-pzpypz)2]·2MeOH (3·2MeOH), one mononuclear Cu(ii) complex [CuCl2(pzpypzH)] (4) and one trinuclear Cu(i)/Cu(ii) complex [(ICu)(μ-I)2Cu2(μ-pzpypz)2] (5), respectively. Treatment of 4 with two equiv. of AgNO3 in DMF also gave rise to 1.

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Five new glucosylated steroidal glycosides, cantalasaponin I-B(1) (1), I-B(2) (2), I-B(3) (3), I-B(4) (4) and I-B(5) (5), were isolated and purified from the transformed product of the cantalasaponin I by using Toruzyme 3.0 l as biocatalyst. Their structures were elucidated on the basis of high-resolution electrospray ionization mass spectrometry, one-dimensional ((1) H and (13) C NMR) and two-dimensional [COSY, heteronuclear single-quantum correlation (HSQC), HMBC and HSQC-TOCSY] NMR spectral analyses and chemical evidence.

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Five new steroidal glycosides, timosaponin J ( 1), timosaponin K ( 2), (25 S)-karatavioside C ( 5), timosaponin L ( 6), and (25 S)-officinalisnin-I ( 8), together with eight known steroidal saponins, timosaponin E (1) ( 3), purpureagitosid ( 4), timosaponin BII ( 7), timosaponin B III ( 9), anemarrhenasaponin I ( 10), anemarrhenasaponin III ( 11), anemarrhenasaponin A (2) ( 12), and timosaponin A III ( 13), were isolated from the rhizomes of Anemarrhena asphodeloides. Their structures were elucidated on the basis of spectroscopic and chemical evidence. The aglycones of compounds 1 and 2 are new aglycones.

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Steroidal saponins in Rhizoma Paridis attract scientific attentions for their structural diversity and significant bioactivities. In this work, an ultra performance liquid chromatography coupled with a hybrid quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS) was used to rapidly separate and identify steroidal saponins from the extract of the rhizome of Paris polyphylla var. yunnanensis (PPY).

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In order to clarify the chemical constituents in Qiliqiangxin capsule, a rapid ultra-performance liquid chromatography/orthogonal acceleration time-of-flight mass spectrometry (UPLC-Q-TOF/MS(E)) method was established. Forty peaks were identified on line using this method. The herbal sources of these peaks were assigned.

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Nine spirostanol saponins (1-9) and seven mixtures of 25 R and 25 S spirostanol saponin isomers (10-16) were obtained from the seeds of Trigonella foenum-graecum after enzymatic hydrolysis of the furostanol saponin fraction by β-glucosidase. Their structures were determined by NMR and MS spectroscopy. Among them, 1- 4, 6, 8, and 9 were new compounds and five, 11B, 12A, 13B, 14A, and 14B, were new structures observed from seven mixtures.

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This study was aimed to investigate the effect of bortezomib alone or combined with arsenic trioxide on the apoptosis of Jurkat cells and expression of livin mRNA. The Jurkat cells were cultured and treated with different concentrations of bortezomib, arsenic trioxide or their combination for 24 hours. Then, the expression of livin mRNA was detected by RT-PCR, the cell proliferation was analyzed with MTT assay and flow cytometry.

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Timosaponin BII (BII), a steroidal saponin showing potential anti-dementia activity, was converted into its glucosylation derivatives by Toruzyme 3.0L. Nine products with different degrees of glucosylation were purified and their structures were elucidated on the basis of (13)C NMR, HR-ESI-MS, and FAB-MS spectra data.

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Two new spirostanol saponins, named kingianoside H (1) and kingianoside I (2), were isolated from the processed rhizomes of Polygonatum kingianum, along with a known triterpenoid saponin ginsenoside-Rc (3), four known spirostanol saponins Tg (4), (5), polygonatoside C(1) (6) and ophiopogonin C' (7). The structures of the new compounds were elucidated by detailed spectroscopic analyses, including 1D and 2D NMR techniques and chemical methods. Compounds 3 and 5 were first reported from the genus Polygonatum.

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Further studies on the fresh rhizomes of Polygonatum kingianum led to the isolation of one new spirostanol saponin (25R)-kingianoside G (1), and two pairs mixture of 25R and 25S stereoisomeric spirostanol saponins (25R, S)-pratioside D1 (2a, 2b) and (25R, S)-kingianoside A (3a, 3b), among them 2b and 3b were new spirostanol saponins, together with another two known compounds, disporopsin (4) and daucosterol (5). The structures of the new saponins were determined by detailed analysis of their 1D and 2D NMR spectra, and chemical evidences.

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Two new furostanol saponins and one new spirostanol saponin were isolated from the rhizome of Paris polyphylla Smith var. yunnanensis, together with 18 known steroidal saponins. The structures of the new steroidal saponins were elucidated as 26-O-beta-D-glucopyranosyl-(25R)-5-ene-furost-3 beta, 17 alpha, 22 alpha, 26-tetrol-3-O-alpha-L-arabinofuranosyl-(1-->4)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranoside (2, parisyunnanoside A), 26-O-beta-D-glucopyranosyl-(25R)-5, 20 (22)-diene-furost-3 beta, 26-diol-3-O-alpha-L-arabinofuranosyl-(1-->4)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranoside (7, parisyunnanoside B), and (25R)-spirost-5-ene-3 beta, 12 alpha-diol-3-O-alpha-L-rhamnopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->4)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranoside (13, parisyunnanoside C) by MS and 1 D and 2 D NMR analysis.

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Four triterpenoid saponins were isolated from Albizziae cortex, and a complete assignment of their (1)H and (13)C NMR spectra was carried out using 1D and 2D NMR ((1)H-(1)H COSY, HSQC, HMBC, and HSQC-TOCSY) methods. Their (1)H NMR assignments were reported for the first time and some of their (13)C NMR spectral data reported in literature were corrected.

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An analysis of the polar extracts from Allium ascalonicum L. led to the isolation of two new furostanol saponins (compound 1 and 2) and two known furostanol saponins (compound 3 and 4). On the basis of 1D and 2D NMR (including (1)H, (13)C NMR, (1)H--(1)H COSY, HSQC, TOCSY, HMBC, and NOESY), FAB-MS spectrometry, and chemical methods, their structures were elucidated as (25R)-26-O-beta-D-glucopyranosyl-22-hydroxy-5alpha-furost-2-one-3beta, 5, 6beta, 26-tetraol-3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside (ascalonicoside C, 1), (25R)-26-O-beta-D-glucopyranosyl-22-methoxy-5alpha-furost-2-one-3beta, 5, 6beta, 26-tetraol- 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranoside (ascalonicoside D, 2), (25R)-26-O-beta-D-glucopyranosyl-22-hydroxy-5-ene-furostan-3beta, 26-diol-3-O-alpha-L-rhamnopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->4)-[alpha-L-rhamnopyranosyl-(1-->2)]-beta-D-glucopyranoside (dichotomin, 3), and (25R)-26-O-beta-D-glucopyranosyl-22-hydroxy-5-ene-furostan-3beta, 26-diol-3-O-alpha-L-rhamnopyranosyl-(1-->2)-[alpha-L-arabinofuranosyl-(1-->4)]-beta-D- glucopyranoside (parisaponin I, 4).

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Objective: To isolate and identify steroidal saponins from the rhizomes of Dioscorea septemloba Thunb.

Methods: The compounds were isolated by solvent extraction, column chromatography on silica gel and ODS, and their structures were elucidated on the base of chemical and spectral analyses.

Results: Three steroidal saponins were isolated from the rhizomes of Dioscorea septemloba Thunb, and their structures were detemined as dioscin (I), protodioscin (II), protogracillin (III).

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