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Biomedical subjects

Dean Guo

Publications and source records attributed to Dean Guo.

At least 37 records · Page 2Linked to original sources
PubMed2005

Determination of triptolide and triptonide in human plasma by high-performance liquid chromatography.

An isocratic high-performance liquid chromatographic method for determination of triptolide and triptonide in human plasma is described. Plasma samples were extracted with OasisHLB solid-phase extraction (SPE) cartridges. After pretreatment, they were separated on a SymmetryShieldRP(18) column with a mobile phase of acetonitrile-water (40:60,v/v) at 40 degrees C. The effluent was monitored at UV 217 nm. Linearity (0.010-1.0 mg/L) was good, and the lower limit of detection was 3 ng/mL for triptolide and 4.5 ng/mL for triptonide (S/N = 3). The relative standard deviations of intra- and inter-day assay were less than 15% and the recoveries were better than 80%. The developed method was applied to the determination of triptolide and triptonide concentration in a patient's plasma after taking the medicament containing Tripterygium wilfordii Hook. F.

Adult↗
PubMed2005

Analysis of homoisoflavonoids in Ophiopogon japonicus by HPLC-DAD-ESI-MSn.

The homoisoflavonoids in Ophiopogon japonicus (Thunb.) Ker-Gawler were analyzed by high-performance liquid chromatography-diode array detection-electrospray ion trap tandem mass spectrometry (HPLC-DAD-ESI-MSn). Homoisoflavonoids gave prominent [M - H]- ions by electrospray ionization monitored in the negative ion mode. They could be classified into two types depending on the fragmentation behavior of their [M - H]- ions in the ion trap mass analyzer. The [M - H]- ions of homoisoflavonoids with a saturated C2-3 bond underwent C3-9 bond cleavage to lose the B-ring, which was followed by the loss of a molecule of CO. The [M - H]- ions of homoisoflavonoids with a C2-3 double bond usually eliminated a CO molecule first, and then underwent the cleavage of C3-9 or C9-1' bonds. For homoisoflavonoids with a C-6 formyl group, however, the neutral loss of CO was the first fragmentation step; the presence of a methoxyl group at C-8 could lead to the cleavage of C-ring. No retro Diels-Alder (RDA) fragmentation characteristic for normal flavonoids was observed. The above fragmentation rules were reported for the first time, and were implemented for the analysis of homoisoflavonoids in O. japonicus. The CHCl3-MeOH extract was separated on a Zorbax Extend-C18 column, eluting with a acetonitrile-0.3% acetic acid gradient. A total of 18 homoisoflavonoids, including seven new minor constituents, were identified or tentatively characterized based on the UV spectra and tandem mass spectra of the HPLC peaks.

Chromatography, High Pressure Liquid↗
PubMed2005

Silenorubicosides A-D, triterpenoid saponins from Silene rubicunda.

Four novel triterpenoid saponins, silenorubicosides A-D (1-4), together with four known saponins were isolated from the roots of Silene rubicunda. Their structures were established on the basis of spectroscopic analysis, including extensive 1D and 2D NMR (DQF-COSY, TOCSY, HETCOR, HMBC, and phase-sensitive NOESY) studies and chemical degradation.

Carbohydrate Sequence↗
PubMed2005

Microbial transformation of 20(S)-protopanaxatriol by Mucor spinosus.

Microbial biotransformation of 20(S)-protopanaxatriol (1) by the fungus Mucor spinosus (AS 3.3450) yielded four new metabolites, the structures of which were determined to be 12-oxo-15alpha-hydroxyl-20(S)-protopanaxatriol (2), 27-hydroxyl-20(S)-protopanaxatriol (3), 12-oxo-26-hydroxyl-20(S)-protopanaxatriol (4), and 12-oxo-27-hydroxyl-20(S)-protopanaxatriol (5), respectively, on the basis of their chemical and spectroscopic data. All the new metabolites, as well as the substrate, had significant cytotoxic effects on HL-60 cells (human leukemia cells).

Antineoplastic Agents↗
PubMed2005

Microbial hydroxylation of bufalin by Cunninghamella blakesleana and Mucor spinosus.

The microbial transformation of a cytotoxic bufadienolide, bufalin (1), was carried out using two strains of filamentous fungi. Cunninghamella blakesleana catalyzed the specific 12alpha-hydroxylation of bufalin and produced 12alpha-hydroxybufalin (2) and 7beta,12alpha-dihydroxybufalin (3) as the major metabolites, together with 7beta-hydroxybufalin (4) and 12beta-hydroxybufalin (5) in low yields. Two minor products were isolated from the culture broth of Mucor spinosus and were identified as 7beta,15alpha-dihydroxybufalin (6) and 5beta,7beta-dihydroxybufalin (7), respectively. Metabolites 2, 3, 6, and 7 are new compounds, and their structures were fully characterized by NMR and MS spectroscopy.

Biotransformation↗
PubMed2005

Acryloylated glucose 3-nitropropanoates from Indigofera kirilowii.

Two unique glucose esters of 3-nitropropanoic acid with acryloyl moieties, kirilowin A and kirilowin B, were isolated from the roots of Indigofera kirilowii. Their structures were elucidated by detailed spectroscopic analysis. The two acrylates constitute new additions to the toxic glucose conjugates of 3-nitropropanoic acid in angiosperms.

Acrylates↗
PubMed2005

Determination of four active saponins of Panax notoginseng in rat feces by high-performance liquid chromatography.

A method is developed for the determination of ginsenoside Rg1, Rb1, Rd, and notoginsenoside R1 of Panax notoginseng (PNS) in rat feces after oral and intravenous administration of total saponins of PNS. The fecal samples are treated with organic extraction and solid-phase extraction prior to high-performance liquid chromatography. The calibration curves for the four saponins are linear in the given concentration ranges. The precision of the method is in the range of 1.0-10.0% (relative standard deviation), and the accuracy is between 80.0% and 110%. The recoveries of this method are all over 75%. This method is successfully applied to the analyses of fecal samples of rats treated with PNS.

Animals↗
PubMed2005

[Effect of rare-earth element Eu3+ on callus growth and flavonoids content in Glycyrrhiza uralensis].

The effect of rare-earth element Eu3+ on callus growth and its flavonoids content in Glycyrrhiza uralensis was studied. The results showed that lower concentration of rare-earth element Eu3+ could promote the callus growth and flavonoids productions. 0.1 mg/l Eu3+ was the most suitable for the biomass accumulation of the callus and flavonoids biosynthesis. In that concentration flavonoids content was 2.7 times and liquiritigenin was 4 times as that of the control.

Culture Media↗
PubMed2004

Solid-phase extraction-liquid chromatographic method for the determination and pharmacokinetic studies of albiflorin and paeoniflorin in rat serum after oral administration of Si-Wu decoction.

A sensitive and rapid high-performance liquid chromatography (HPLC) method with solid-phase extraction (SPE) to simultaneously determine albiflorin and paeoniflorin in rat serum was described. Serum samples were pretreated with solid-phase extraction using Extract-Clean cartridges, and the extracts were analyzed by HPLC on a reversed-phase C(18) column and a mobile phase of acetonitrile-0.03% formic acid (17:83 (v/v)) with ultraviolet detection at 230 nm. Pentoxifylline was used as the internal standard (IS). The linear ranges of the calibration curves were 29-1450 ng/ml for albiflorin and 10-2000 ng/ml for paeoniflorin. The intra- and inter-day precisions (R.S.D.) were <or=10.49% for albiflorin and <or=11.29% for paeoniflorin, respectively. Mean recovery was determined to be 89.75% for albiflorin and 85.82% for paeoniflorin. The limit of quantification was 29 ng/ml for albiflorin and 10 ng/ml for paeoniflorin, respectively. The validated method was applicable to pharmacokinetic studies of albiflorin and paeoniflorin from rat serum after oral administration of Si-Wu decoction. The pharmacokinetic study indicated that albiflorin and paeoniflorin had poor absorption and rapid elimination. This assay result was necessary for the pharmacokinetic evaluation of Si-Wu decoction.

Administration, Oral↗
PubMed2004

Simultaneous determination of four bufadienolides in human liver by high-performance liquid chromatography.

A high-performance liquid chromatographic method for the simultaneous quantitation of four bufadienolides-cinobufotalin, bufalin, cinobufagin and resibufogenin-in human liver was investigated. The procedure involved solid phase extraction of human liver with an Oasis HLB cartridge coupled with reversed-phase HPLC and photodiode array detection. Recoveries obtained from spiked liver for the bufadienolides were better than 70%. The linearity was studied up to 1.2 mg/kg and the detection limits of the method were 0.4 ng for cinobufotalin and bufalin and 0.5 ng for cinobufagin and resibufogenin. The developed method was successfully applied to a lethal poisoning case.

Adult↗
PubMed2004

Simultaneous determination of albiflorin and paeoniflorin in rat urine by solid-phase extraction and high-performance liquid chromatography following oral administration of Si-Wu decoction.

A high performance liquid chromatographic method (HPLC), together with solid phase extraction (SPE), was developed for simultaneous determination of albiflorin and paeoniflorin in rat urine after oral administration of Si-Wu decoction. The samples were pretreated with solid phase extraction using Extract-Cleantrade mark cartridges. Analysis of the extract was performed on a reversed-phase C18 column and a mobile phase made up of acetonitrile and 0.03% formic acid (17:83, v/v). UV detection was set at 230 nm. The assay was linear over the range 2.625-52.50 mg/mL for albiflorin and 3.875-77.50 microg/mL for paeoniflorin. The average percentage recoveries of three spiked urines were 97.01 +/- 3.32 and 102.32 +/- 6.97 for albiflorin and paeoniflorin, respectively. The intra-day precision (RSD) ranged from 0.21 to 1.79% at concentrations of 4.20, 10.50, 26.25 and 39.375 microg/mL of albiflorin and 0.12 to 2.92% at concentrations of 3.875, 10.85, 23.25 and 58.125 microg/mL of paeoniflorin, and inter-day precision (RSD) was from 1.02 to 1.86% for albiflorin and 0.94 to 3.30% for paeoniflorin, at the same four concentrations. This method was applied in order to analyze albiflorin and paeoniflorin in rat urine following oral administration of traditional Chinese medicinal preparation of Si-Wu decoction.

Animals↗
PubMed2004

HPLC determination of four active saponins from Panax notoginseng in rat serum and its application to pharmacokinetic studies.

Four main active saponins (ginsenosides Rg1, Rb1, Rd and notoginsenoside R1) in Panax notoginseng in rat serum after oral and intravenous administration of total saponins of P. notoginseng (PNS) to rats were determined using a simple and sensitive high-performance chromatographic method. The serum samples were pretreated with solid-phase extraction before analysis. The calibration curves for the four saponins were linear in the given concentration ranges. The intra-day and inter-day assay coefficients in serum were less than 10.0% and the recoveries of the method were higher than 80.0% in the high, middle and low concentrations. This method was applied to study the pharmacokinetics following oral and intravenous administration of PNS.

Animals↗
PubMed2004

Novel cytotoxic bufadienolides derived from bufalin by microbial hydroxylation and their structure-activity relationships.

Microbial transformation was used to prepare novel cytotoxic bufadienolides. Twelve products (3-14) were obtained from bufalin (1) by the fungus Mucor spinosus. Their structures were elucidated by high-resolution mass spectroscopy (HR-MS) and extensive NMR techniques, including 1H NMR, 13C NMR, DEPT, 1H-1H correlation spectroscopy (COSY), two dimensional nuclear Overhauser effect correlation spectroscopy (NOESY), heteronuclear multiple quantum coherence (HMQC), and heteronuclear multiple bond coherence (HMBC). Compounds 3, 4, 9 and 11-14 are new mono- or dihydroxylated derivatives of bufalin with novel oxyfunctionalities at C-1beta, C-7beta, C-11beta, C-12beta and C-16alpha positions. The in vitro cytotoxic activities against human cancer cell lines of 3-14, together with 16 biotransformed products derived from cinobufagin (15-30) were determined by the MTT method, and their structure-activity relationships (SAR) were discussed.

Bacteria↗
PubMed2004

Maltol glucosides from the tuber of Smilax bockii.

Two maltol glucosides, bockiosides A and B, along with 10 known compounds, were isolated from the tuber of Smilax bockii (Liliaceae), and their structures were elucidated by spectral experiments, chemical analysis and comparison with literature data.

Glucosides↗
PubMed2004

Saponins from the flower buds of Buddleja officinalis.

Five new saponins, mimengosides C-G (1-5), were isolated from the flower buds of Buddleja officinalis along with five known compounds, namely, songaroside A, acteoside, phenylethyl 2-glucoside, echinacoside, and phenylethyl alcohol 8-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside. The structures of 1-5 were elucidated using spectroscopic and chemical methods, and these compounds were evaluated for their inhibitory effects against HL-60 leukemia cells.

Buddleja↗
PubMed2004

Microbial glycosylation of four free anthraquinones by Absidia coerulea.

Absidia coerulea transformed four anthraquinones from rhubarb, chrysophanol, physcion, emodin and aloe-emodin to their corresponding glycosylated metabolites. The structures of the products were characterized as chrysophanol 8-O-beta-D-glucoside, physcion 8-O-beta-D-glucoside, emodin 6-O-beta-D-glucoside, and aloe-emodin 1-O-beta-D-glucoside, respectively.

Absidia↗