PubMed Health⌕ Search

Biomedical subjects

Hong-Xi Xu

Publications and source records attributed to Hong-Xi Xu.

At least 19 recordsLinked to original sources
PubMed2006

Maoecrystal Z, a cytotoxic diterpene from Isodon eriocalyx with a unique skeleton.

[structure: see text] A novel diterpene with an unprecedented tetracyclic 6,7:8,15-di-seco-7,20-olide-6,8-cyclo-ent-kaurane skeleton, named maoecrystal Z (1), has been isolated from the leaves of a Chinese medicinal herb, Isodon eriocalyx (Labiatae). Its structure was determined by comprehensive NMR and MS spectroscopic analysis coupled with single-crystal X-ray crystallographic diffraction. Compound 1 exhibited comparable inhibitory effect against human K562 leukemia, MCF7 breast, and A2780 ovarian tumor cells with IC(50) = 2.90, 1.63, and 1.45 microg/mL and with camptothecin and paclitaxel as the positive controls.

Antineoplastic Agents, Phytogenic↗
PubMed2006

Combinative method using HPLC quantitative and qualitative analyses for quality consistency assessment of a herbal medicinal preparation.

A selective and efficient quality consistency assessment system was developed for monitoring the manufacturing processes of a Chinese herbal preparation, qingfu guanjieshu (QFGJS) capsule, and for assessing its stability over time. This system is based on quantitative determination of four marker compounds, i.e., sinomenine, paeoniflorin, paeonol, and curcumin, and on qualitative fingerprinting analysis of QFGJS using high-performance liquid chromatography-photodiode array detection (HPLC-DAD) method. The separation was performed on a Phenomenex ODS column by gradient elution with acetonitrile and aqueous phase (containing 0.1% phosphoric acid, adjusted with triethylamine to pH 3.5+/-0.2) at a flow-rate of 1.0 ml/min. In fingerprinting analysis, the chemical characteristics of four herbs present in QFGJS (excluding radix Aconiti Lateralis Preparata) were present in the HPLC chromatographic file. In addition, quantitative determination of hypaconitine was carried out with our published HPLC method as a supplement for quality control of the radix Aconiti Lateralis Preparata in QFGJS. The results showed that the contents of these five marker compounds and HPLC fingerprint profiles of three batches of QFGJS products collected at 3 months after production in the stability testing were relatively consistent. This well-developed method could be used for quality assessment of the complex preparations of herbal medicine.

Aconitine↗
PubMed2006

Role of nitric oxide in the vasorelaxant and hypotensive effects of extracts and purified tannins from Geum japonicum.

Crude extracts and three purified tannins from Geum japonicum Thunberg (Rosaceae) were examined for relaxant effects in isolated rat thoracic aorta and for hypotensive effects in anesthetized normotensive and hypertensive rats. The acetone extract and the butyl alcohol extract of Geum japonicum at a cumulative concentration of 30mug/ml potently relaxed phenylephrine-precontracted aortic rings by 73+/-5% and 80+/-7%, respectively, without affecting the resting tension of these vessels. Removal of the vascular endothelium, inhibition of nitric oxide (NO) synthase with N(omega)-nitro-l-arginine (l-NA) or inhibition of cGMP biosynthesis with methylene blue all abolished the vasorelaxant effects of the Geum japonicum extracts. Addition of l-arginine, the substrate for NO biosynthesis, reversed the inhibitory effects of l-NA. Similar vasorelaxant effects of 82+/-10%, 61+/-8% and 82+/-14%, were observed with the purified tannins, penta-O-galloyl-beta-glucoside, casuariin and 5-desgalloylstachyurin, respectively, at a cumulative concentration of 10muM. Intravenous injection of the butyl alcohol extract of Geum japonicum at a cumulative dose of 2.5mg/kg into both hypertensive and normotensive rats resulted in a marked reduction in the mean arterial blood pressure by 46+/-6% and 34+/-7%, respectively, which was abolished by prior injection of l-NA. Therefore, these results suggest that tannins may be responsible for the vasorelaxant and hypotensive effects of Geum japonicum, mediated via endogenous NO and subsequent cGMP formation. The data suggest that extracts of Geum japonicum may have potential use as new anti-hypertensive agents for lowering arterial blood pressure in hypertensive patients.

Animals↗
PubMed2006

High-performance thin-layer chromatographic fingerprints of isoflavonoids for distinguishing between Radix Puerariae Lobate and Radix Puerariae Thomsonii.

The roots of Pueraria lobata (Wild.) Ohwi and Pueraria thomsonii Benth have been officially recorded in all editions of Chinese Pharmacopoeia under the same monograph 'Gegen' (Radix Puerariae, RP). However, in its 2005 edition, the two species were separated into both individual monographs, namely 'Gegen' (Radix Puerariae Lobatae, RPL) and 'Fenge' (Radix Puerariae Thomsonii, RPT), respectively, due to their obvious content discrepancy of puerarin, the major active constituent. In present paper, the fingerprint of high-performance thin-layer chromatography (HPTLC) combining digital scanning profiling was developed to identify and distinguish the both species in detail. The unique properties of the HPTLC fingerprints were validated by analyzing ten batches of Pueraria lobata and P. thomsonii samples, respectively. The common pattern of the HPTLC images of the roots of Pueraria spp. and the respective different ratios of the chemical distribution can directly discern the two species. The corresponding digital scanning profiles provided an easy way for quantifiable comparison among the samples. Obvious difference in ingredient content and HPTLC patterns of the two species questioned their bio-equivalence and explained that recording both species separately in the current edition of Chinese Pharmacopoeia (2005 edition) is reasonable due to not only the content of major constituent, puerarin, but also the peak-to-peak distribution in the fingerprint and integration value of the total components. Furthermore, the HPTLC fingerprint is also suitable for rapid and simple authentication and comparison of the subtle difference among samples with identical plant resource but different geographic locations.

Chromatography, Thin Layer↗
PubMed2006

Antitussive effects of Stemona tuberosa with different chemical profiles.

The root tubers of Stemona tuberosa, Stemona japonica and Stemona sessilifolia are recognized by the Pharmacopoeia of the People's Republic of China as authentic sources of the herb Radix Stemonae (Baibu). Careful anatomical analyses of these three species, whose identities were confirmed by flowering and fruiting samples, revealed that the root tubers of Stemona tuberosa could be distinguished from those of the other two species by the presence of scattered fibers in the cortex and pith and by the absence of thickened striations on the surface of velamen cells. HPLC analyses demonstrated that the total alkaloid profiles could be grouped into four types represented as the major component by stenine-type Stemona alkaloids such as tuberostemonine (4) and neotuberostemonine (3), or by non-stenine types such as croomine (1) and stemoninine (2). Nevertheless, all these samples demonstrated different degrees of antitussive properties in guinea pigs. These results suggested that non-stenine-type of Stemona alkaloids also contributed to the antitussive properties. The variations in chemical profiles among herb samples add difficulty in ensuring quality control in botanical products.

Alkaloids↗
PubMed2006

Puerarin decreases serum total cholesterol and enhances thoracic aorta endothelial nitric oxide synthase expression in diet-induced hypercholesterolemic rats.

Hypercholesterolemia is a dominant risk factor for the development and progression of atherosclerosis and cardiovascular diseases. Natural compounds have been proved to be useful in lowering serum cholesterol to slow down the progression of cardiovascular diseases. Pueraria lobata is employed clinically to treat cardiovascular diseases in China. In the present study, the atheroscleroprotective potential of the herb's major active compound, puerarin, was investigated by monitoring serum lipid profile and major enzyme expressions on cholesterol homeostasis in Sprague-Dawley rats fed with control diet, hypercholesterolmic diet or hypercholesterolmic diet plus administration of puerarin (300 mg/kg/day, p.o.) for 4 weeks. Puerarin markedly attenuated the increased total cholesterol induced by hypercholesterolmic diet in both serum and liver. It caused a significant reduction in the atherogenic index. Expression of mRNA for hepatic 7alpha-hydroxylase (CYP7A1) was significantly enhanced but not for those of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) and lanosterol 14alpha-demethylase (CYP51). To further explore the atheroscleroprotective potential of puerarin, acetylcholine induced endothelium-dependent vasorelaxation and endothelial nitric oxide synthase (eNOS) expression on isolated thoracic aortas were analyzed. Animals administered with puerarin suppressed the hypercholesterolemic diet induced impairment of eNOS expression, whereas there was no significant difference in the endothelium-dependent vasorelaxation among various groups of animals. These data indicated that puerarin reduced the atherogenic properties of dietary cholesterol in rats. Its hypocholesterolemic function may be due to the promotion of cholesterol and bile acids excretion in liver. Whether puerarin targets directly on cholesterol homeostasis or both cholesterol homeostasis and endothelial function remains to be determined.

Acetylcholine↗
PubMed2006

A pair of novel cytotoxic polyprenylated xanthone epimers from gamboges.

Two new polyprenylated xanthone epimers were isolated from gamboges of Garcinia hanburyi, and identified by detailed spectroscopic analysis as 30-hydroxygambogic acid (2a) and its (2S)-epimer 30-hydroxyepigambogic acid (2b). Both compounds exhibited significant cytotoxicities against the human leukemia K562/S and the corresponding doxorubicin-resistant K562/R cell lines (Table 2).

Cell Line, Tumor↗
PubMed2006

Analyses of Stemona alkaloids in Stemona tuberosa by liquid chromatography/tandem mass spectrometry.

Alkaloid profiles in Stemona tuberosa were found to be highly variable. Six Stemona alkaloids isolated from the plant were subjected to on-line high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) and tandem mass spectrometry (MS/MS) analyses. Their fragmentation patterns and products were useful for their characterization. The LC/MS fingerprints of these alkaloids, though variable among samples, could provide an overall characterization of the authenticity and quality of this species and help to differentiate it from S. japonica and S. sessilifolia, as all three species are recognized as genuine sources of the herb Radix Stemonae in the Pharmacopoeia of the People's Republic of China.

Alkaloids↗
PubMed2006

Quantitative analyses of indoloquinazoline alkaloids in Fructus Evodiae by high-performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry.

Fructus Evodiae (Wuzhuyu), the fruits of Evodia rutaecarpa and related varieties, is widely used in traditional Chinese medicine. The bioactive constituents include the indoloquinazoline alkaloids rutaecarpine, evodiamine and dehydroevodiamine. A new assay based on high-performance liquid chromatography/atmospheric pressure chemical ionization tandem mass spectrometry (HPLC/UV/APCI-MS/MS) was developed for the measurement of the indoloquinazoline alkaloids in commercial Fructus Evodiae products. Initially, the MS/MS fragmentation pathways of indoloquinazoline alkaloids were investigated to identify fragment ions that might be useful for the sensitive and selective detection of trace indoloquinazoline alkaloids during LC/MS/MS. Then, quantitative MS analysis of five indoloquinazoline alkaloids in 12 commercial Fructus Evodiae products from different geographical sources was performed. Analyte recovery was in the range of 97.5-105.3% for all with relative standard deviations (RSDs) below 6%, the intra-assay and inter-assay RSDs were less than 7%, and good linear relationships were shown with correlation coefficients for the analytes exceeding 0.999. Therefore, this LC/MS/MS assay facilitated the rapid quantitative analysis of rutaecarpine, evodiamine, evodiamide, 14-formyldihydrorutaecarpine and dehydroevodiamine in 12 commercial Fructus Evodiae products with excellent recovery, repeatability, accuracy and sensitivity. This method is simple and specific and can be used for identification and quality control of this traditional Chinese remedy.

Chromatography, High Pressure Liquid↗
PubMed2006

Alkaloids and chemical diversity of Stemona tuberosa.

Phytochemical investigation of the chemical components of Stemona tuberosa led to the isolation of two new alkaloids named tuberostemonine K (1) and tuberospironine (2), together with the known tuberostemonine (3). The new structures of 1 and 2 were elucidated through extensive spectroscopic analyses, while the molecular structure of 3 was confirmed by X-ray analysis. A gradient reversed-phase HPLC-ELSD method was established for the investigation of the chemical diversity of S. tuberosa from 13 localities, and four types of chemical variation featured by the major components 3, neotuberostemonine (4), croomine (5), and stemoninine (6), respectively, were observed.

Alkaloids↗
PubMed2006

Cytotoxic polyprenylated xanthones from the resin of Garcinia hanburyi.

Thirteen xanthones (1-13) were isolated from the resin of Garcinia hanburyi. Among them, two new compounds (namely gaudichaudic acid, and isogambogenic acid, 1, 2), and one new natural product (deoxygaudichaudione A, 3) were identified on the basis of extensive spectral evidence including detailed 2D NMR data. Ten of these xanthones were tested for their cytotoxicities against human leukemia K562 (K562/S) and doxorubicin-resistant K562 (K562/R) cell lines, and showed similar inhibitory effects on both cell lines, suggesting that this group of polyprenylated xanthones might not be multidrug resistance (MDR) substrates.

Antineoplastic Agents, Phytogenic↗
PubMed2005

Isolation and chemotaxonomic significance of tuberostemospironine-type alkaloids from Stemona tuberosa.

An alkaloid named 6alpha-hydroxycroomine (1) as well as the known croomine (2), both belonging to the tuberostemospironine-alkaloid type, were isolated from Stemona tuberosa as the major components. The structure of 1 was elucidated through extensive spectroscopic analyses. Comparison of the HPLC profiles of the total alkaloids and the crude methanol extract showed that both compounds are naturally occurring. The first isolation of 1 and 2 from S. tuberosa has chemotaxonomic significance, confirming the close relationship between Stemona and Croomia. The trnL sequences of plants from the four genera of Stemonaceae cluster together as a clade, further lending support to retaining them in a single family.

Alkaloids↗
PubMed2005

Isolation of iridoid and secoiridoid glycosides and comparative study on Radix gentianae and related adulterants by HPLC analysis.

HPLC profile guided study led to the isolation of an acylated secoiridoid glycoside, named gentiotrifloroside (1), together with six known compounds, i.e., loganic acid (2), 6-O-beta-d-glucopyranosylgentiopicroside (3), swertiamarin (4), gentiopicroside (5), sweroside (6) and 2 -(o,m-dihydroxybenzyl)-sweroside (7) from Gentiana triflora and Gentiana rigescens. The structure of 1 was deduced from one- and two-dimensional NMR spectroscopic experiments. Compounds 1-7 were used successfully as chemical markers for the comparison of the four species of Gentiana used as Radix gentianae. Additionally, differentiation of Gentiana species mentioned and those used as adulterants was evaluated. The close similarity of chemical composition among the four genuine Gentiana species explain their popular usage as R. gentianae in Chinese medicine. We have also shown that the variation of chemical composition in R. gentianae and related adulterants agree well with their botanical phylogeny.

Animals↗
PubMed2005

The effects of sinomenine on intestinal absorption of paeoniflorin by the everted rat gut sac model.

Paeoniflorin and sinomenine, derived from the root of Paeonia lactiflora Pall. (family Ranunculaceae) and the stem of Sinomenium acutum Rehder & Wilson (family Menispermaceae), respectively, have been, and are currently, widely used for treatment of rheumatic and arthritic diseases in China and Japan. Our previous studies demonstrated that sinomenine could significantly improve the bioavailability of paeoniflorin in rats, but the underlying mechanisms remain unknown. The present study aims to investigate the intestinal kinetic absorptive characteristics of paeoniflorin as well as the absorptive behavior influenced by co-administration of sinomenine using an in vitro everted rat gut sac model. The results showed a good linear correlation between the paeoniflorin absorption in sac contents and the incubation time from 0 to 90 min. However, the concentration dependence showed that a non-linear correlation exists between the paeoniflorin absorption and its concentrations from 10 to 160 microM, and the absorption was saturated at about 80 microM of the drug. Sinomenine at 16 and 136 microM concentrations could significantly enhance the absorption of paeoniflorin (20 microM) by 1.5- and 2.5-fold, respectively. Moreover, two well-known P-glycoprotein inhibitors, verapamil and quinidine, could significantly elevate the absorption of paeoniflorin by 2.1- and 1.5-fold, respectively. Furthermore, sinomenine in a pattern, which influenced paeoniflorin's absorption, manifested as similar to that of P-glycoprotein inhibitors. In conclusion, sinomenine significantly enhance the intestinal absorption of paeoniflorin, subsequently improve the bioavailability of paeoniflorin. The mechanism underlying the improvement of paeoniflorin's bioavailability was proposed that sinomenine could decrease the efflux transport of paeoniflorin by P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

The pharmacokinetics and tissue distribution of sinomenine in rats and its protein binding ability in vitro.

Sinomenine, an alkaloid derived from the Chinese medical plant Sinomenium acutum, was studied with regard to its pharmacokinetics and tissue distribution in rats, and to its protein binding ability in the plasma of rats and rabbits and in the solutions of albumin and alpha-1-acid-glycoprotein. An HPLC analytical method was developed for determining sinomenine. The results demonstrated that oral administration with a single dosage at a rate of 90 mg sinomenine/kg in rats achieved about 80% bioavailability, while most of the other pharmacokinetic parameters were similar to the data from the animals treated intravenously. This indicates that oral administration of sinomenine would be appropriate in clinics. In rats, at 45 min after oral dosage, the drug was found to distribute widely in the internal organs, with tissue concentrations (from highest to lowest) in the order of kidneys, liver, lungs, spleen and heart, brain and testicles. At 90 min after dosing, the tissue concentrations in the organs were markedly decreased. The liver and kidneys manifested as the dominant organs with high tissue concentrations that might be responsible for metabolism and elimination of sinomenine. Examination of the protein binding ability showed that sinomenine with 4 microg/ml concentration in the plasma of rats and rabbits or in the albumin solution achieved a protein binding rate of more than 60%, while in the solution of alpha-1-acid-glycoprotein the rate was only about 33%. This result suggests that sinomenine might have much more potent binding ability with albumin than with alpha-1-acid-glycoprotein, resulting from its acidic property.

Administration, Oral↗
PubMed2005

Authentication and quantitative analysis on the chemical profile of cassia bark (cortex cinnamomi) by high-pressure liquid chromatography.

Cassia bark or cortex cinnamomi, the dried stem bark of Cinnamomum cassia Presl. (Lauraceae), is a popular natural spice and a commonly used herb in traditional Chinese medicine. However, adulterants are frequently found in the market. In this study, 44 samples of Cassia bark including bark from seven related Cinnamomum species were collected from fields and market. Four characteristic components, cinnamaldehyde, cinnamic acid, cinnamyl alcohol, and coumarin were determined by RP-HPLC, and a fingerprint comprised of five markers was established. These results showed that cassia barks contained high contents of cinnamaldehyde (13.01-56.93 mg/g). The highest content of cinnamaldehyde (up to 93.83 mg/g) was found in debarked cortex, which is traditionally regarded as having the best quality in local herb shops. In contrast, the adulterants from the other Cinnamomum species, C. wilsonii Camble, C. japonicum Sieb., C. mairei Levl. and C. burmanii (Nees) Blume, contained low contents of cinnamaldehyde (<2.00 mg/g). The content of cinnamaldehyde in C. loureirii Nees was comparable to that in C. cassia. It is suggested that five characteristic peaks by HPLC are suitable for distinguishing genuine cassia bark from the adulterants and could be applied in the quality control of this commodity.

Acrolein↗
PubMed2005

Stability and cytotoxicity of gambogic acid and its derivative, gambogoic acid.

In this study, the stability of gambogic acid (GA), a polyprenylated xanthone with potent cytotoxicities against various cancer cell lines, was evaluated under several experimental conditions including addition of acids, alkalis and organic solvents. GA was stable when dissolved in acetone, acetonitrile, and chloroform, even when acids were added. However, a new derivative was produced after GA was stored in the methanol solution for a week at room temperature. The addition of alkalis could increase the rate of this chemical transformation. This derivative was determined to be gambogoic acid (GOA) by the HPLC-MS comparison with the known compound. GOA was proposed to be the product of neuclophilic addition of methanol to the olefinic bond at C-10 of GA. Furthermore, when these two compounds were tested for their cytotoxicity, GOA showed significantly weaker inhibitory effects than GA. It was therefore deduced that the alpha,beta-unsaturated carbonyl moiety at C-10 contributed to the cytotoxicity of gambogic acid.

Antineoplastic Agents↗