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Biomedical subjects

R S Xu

Publications and source records attributed to R S Xu.

At least 19 recordsLinked to original sources
PubMed2001

A new bicoumarin from Stellera chamaejasme L.

Thirteen compounds were isolated from roots of Stellera chamaejasme L. (Thymelaeaceae). They are 3-sitosterol (2), simplexin (3), pimelea factor P2 (4), daucosterol (5), (+)-3-hydroxy-1,5-diphenyl-1-pentanone (6), 4-ethoxy-benzoic acid (7), 2,4,6-Trimethoxy-benzoic acid (8), (+)-afzelechin (9), fumaric acid (10), N,N-dimethyl-L-aspartic acid (11), umbelliferone (12), daphniretin (13) and a novel bicoumarin named bicoumastechamin (1). Among the known compounds, 7, 8, 9, 10 and 11 were first isolated from this plant, and 6 was first isolated from the natural resources. Their structures have been elucidated on the basis of spectral data. In vitro bioassays showed that 4 inhibited cancer cell growth, 13 exhibited immunomodulatory activity, and 6 exhibited both immunomodulatory and anti-tumor activity.

Chromatography, Gel↗
PubMed2001

[Experimental study on combining selective rhizotomy of different anterior and posterior sacral roots for restoration of bladder function after spinal cord injury].

OBJECTIVE: To investigate an alternative procedure for complete denervation of bladder in the supra-cone cord injury to restore the bladder function. METHODS: Sixteen dogs were included in this study after their spinal cords were transected above the cone. They were divided into 6 groups and performed the rhizotomy of L7 to S3 root in different combination respectively. The bladder and urethra pressure change by electrostimulation during operation and cystometrogram change after operation were tested. RESULTS: 1. Electrostimulation study: for bladder innervation, S2 was the most important and S1 was secondary. While for urethra innervation, S1 was more important than S2. When the anterior and posterior roots of S1 and S2 were intact with rhizotomy of posterior roots of L7 and S3, stimulated the common or posterior root of S1 and S2, the change of pressure in bladder and urethra was the same. When the anterior roots of S1 and S2 were resected with rhizotomy of posterior roots of L7 and S3, the pressure in bladder and urethra was significant decreased compared to stimulating the corresponding posterior roots. 2. Cystometrogram (CMG) study: in the complete deafferented group, resecting the posterior roots of L7 to S3, the bladder became flaccid. While resecting the posterior root of S2 and anterior root of S1 or, resecting the posterior root of S1 and anterior root of S2, combining with rhizotomy of posterior roots of L7 and S3, the CMG curve was similar to the complete deafferented group. In the S1 and S2 intact group, the bladder became spastic. CONCLUSION: Combining rhizotomy of anterior and posterior sacral root in different level has the same effects on bladder as complete deafferentation.

Animals↗
PubMed2001

New biflavanones and bioactive compounds from Stellera chamaejasme L.

AIM: To study the chemical constituents of the root of Stellera chamaejasme L. METHODS: Various column chromatographies on silica gel and RP-18 were employed for isolation and purification. Structures of compounds were elucidated by spectral analysis. RESULTS: Eight lignans and three biflavonoids possessing a C-3/C-3" linkage were isolated. They are ruixianglangdusu A (1) and B (2), 4',4'",5,5",7,7"-hexahydroxy-3,3"-biflavone (3), (+)-kusunokinin (4), lirioresinol-B (5), magnolenin C (6), (-)-pinoresinol monomethyl ether (7), (-)-pinoresinol (8), (+)-matairesinol (9), isohinokinin (10) and (-)-eudesmin (11). CONCLUSION: Compounds 1 and 2 are new biflavanones, 1 is enantiomeric to known chamaejasmenin C, 4, 6, 8, 9, 10 and 11 were isolated from this plant for the first time, and 7 was isolated from natural resources for the first time. In vitro bioassays showed that 3 and 8 exhibited antibacterial activity, and 1, 2, 9 and 11 exhibited immunomodulatory activity.

Adjuvants, Immunologic↗
PubMed2000

An isopimarane diterpene from Euphorbia ebracteolata Hayata.

From the ethanolic extract of the roots of Euphorbia ebracteolata Hayata four compounds were isolated. They are 24-methylenecycloartanone, tirucallol, procesterol and a new isopimarane diterpene, namely yuexiandajisu C. The structure of yuexiandajisu C was elucidated by spectral analysis. The bioassay in vitro showed yuexiandajisu C exhibited immunomodulatory activity.

Adjuvants, Immunologic↗
PubMed1998

Recent advances on bioactive natural products from Chinese medicinal plants.

China has accumulated a rich body of empirical knowledge of the use of medicinal plants for the treatment of various diseases throughout its long history. Chemical studies on Chinese medicinal plants provide a valuable material base for the discovery and development of new drugs of natural origin. In this article recent chemical work on various Chinese medicinal plants is reviewed, including Mussaenda pubescens (Rubiaceae), Isatis indigotica (Cruciferae), Euphorbia fischeriana, and E. ebracteolata (Euphorbiaceae), and Stemona species (Stemonaceae). The structural diversity of the medicinal chemical constituents of the above plants is discussed.

Animals↗
PubMed1997

Triterpenes and triterpenoid saponins from Mussaenda pubescens.

Two novel triterpenoid saponins, named mussaendosides U and V, together with one known saponin and four known triterpenes were isolated from the aerial parts of Mussaenda pubescens (Rubiaceae). The structures were determined on the basis of chemical analysis ad spectral methods. All these compounds were identified for the first time from the genus Mussaenda.

Carbohydrate Conformation↗
PubMed1995

[In vitro inhibition of celastrol on spermatozoa fertilization ability of guinea pig].

The effects of celastrol (Cel), isolated from Tripterygium wilfordii, on guinea pig sperm forward motility (FM), capacitation (Cap), the acrosome reaction (AR) and sperm penetration assay (SPA) were assessed in vitro. Cel (5 micrograms.ml-1) was found to inhibit these spermatozoal functions, and the inhibitions were proportional to the concentrations of Cel used. The potency of inhibition of Cel on the fertilizing ability in guinea pig spermatozoa in vitro seems to follow the order: Cap > FM > SPA > AR. The inhibitory effect appeared to be reversible after washing away Cel if the duration of exposure of spermatozoa to Cel was shorter than 3 h. In a comparative study, the inhibitory effects of Cel on guinea pig sperm FM and AR were significantly stronger than those of gossypol acetic acid.

Animals↗
PubMed1993

[Studies on circular dichroism of diterpenoids from Mallotus anomalus and sesquiterpenoid tussilagone].

This paper reports the circular dichroism and octant rule projection of 5 diterpenoids from Mallotus anomalus (compounds 1-5) and 3 sesquiterpenoids tussilagones (compounds 6-8): they are new compounds. Using ketone octant rule, planar cyclohexenone rule, beta, gamma-unsaturated ketone rule and Harada rule, the nature of A/B and B/C ring fusion was determined, thus, their absolute configurations were assigned.

Circular Dichroism↗
PubMed1992

Four new cycloartane saponins from Curculigo orchioides.

Four new cycloartane-type triterpene glycosides named curculigosaponins G, H, I, and J have been isolated from rhizomes of Curculigo orchioides (Chinese Name: Xiao Mao; Hypoxidaceae). Their structures were elucidated by FAB-MS, 1H-, 13C-NMR, and 2D-NMR analysis and chemical evidence. A pharmacological study showed that curculigosaponin G increased the weight of the thymus in vivo in mice.

Animals↗
PubMed1992

[Studies on the alkaloids of Cephalotaxus. VII. Structures and semi-synthesis of two anticancer cephalotaxine esters].

Two new alkaloids, namely neoharringtonine (1) and anhydroharringtonine (2) with significant antileukemic activity were isolated from Cephalotaxus fortunei Hook f.. Their structures have been established by spectral analyses and semi-synthesis. Seven known alkaloids, deoxyharringtonine (3), isoharringtonine (4), isocephalotaxinone (5), acetylcephalotaxine (6), cephalotaxine (7), harringtonine (8) and homoharringtonine (9), were also isolated and identified.

Animals↗
PubMed1992

[Studies on the alkaloids of Cephalotaxus. IX. Semi-synthesis of cephalotaxine esters and their anti-leukemic activity].

Harringtonine, homoharringtonine, deoxyharringtonine and isoharringtonine isolated from Cephalotaxus plant are the esters of cephalotaxine with significant inhibitory activity against P-388 leukemia. In this investigation seventeen new esters of cephalotaxine type alkaloids have been synthesized. Preliminary pharmacological examination showed that compounds 1, 2, 2 + 3, 6 and 8 showed similar antileukemic activity as homoharringtonine. Compounds 4, 5, 15 and 16 showed moderate inhibitory activity. Some structure activity correlations of these esters were discussed.

Animals↗
PubMed1992

[Phenyl glycosides from Curculigo orchioides].

One new phenyl glycoside and two new chlorophenyl glycosides were isolated from rhizomes of Curculigo orchioides (Chinese name: Xian Mao, Hypoxidaceae). Based on HRMS, FABMS, 1H-, 13C-NMR and other spectral data as well as chemical evidence, the structures of curculigoside B, curculigine B and C were elucidated to be 2-beta-D-glucopyranosyloxy-5-hydroxybenzyl-2'-methoxy-6'-hydroxybe nzoate (I),24-dichloro-3-methyl-5-methoxy-phenol-O-beta-D-apiofuranosyl (1-6)-beta-D-glucopyanoside (III) and 2,4,6-trichloro-3-methyl-5-methoxyphenol-O-beta-D-xylopyranosyl (1-6)-beta-D-glucopyranoside (IV), respectively.

Drugs, Chinese Herbal↗
PubMed1992

[The research of orthodontic therapy in second molar overjet]

The malocclusion of overjet of second molars is very frequent,When the 2183 patients were examined,we found that the above-mentioned malocclusion had 420 cases.It accounts for 19.22%.The factors led this malocclusion are many.The cases of buccoversion of second molar in maxilla and normal of this tooth in mandible are 257.That upper second molar is buccoversion and lower second molar is linguoversion.all in one side,are 104 cases.Upper normal and lower linguoversion are 24.Buccoversion of two second molars only in upper dental arch and lingual position of second molar in one side of lower dental arch are 31.Even that bilateral lower second molars are linguoversion and this tooth of upper jaw in one side is buccoversion are 4.Therefore,we must adopt various technique according to malposition condition of second molar.This paper will describe five corrective.

Journal Article↗
PubMed1991

Studies on bioactive components from Chinese medicinal plants.

Several novel bioactive components isolated from Chinese medicinal plants will be presented. These include novel maytansinoid tumor inhibitors, some new ent-kaurane and rosane diterpenoids from Mallotus anomalus Meer et Chun (Euphorbiaceae), as well as novel insecticide, stemona alkaloids from Stemona parviflora C. H. Wright (Stemonaceae). Both are native plants of Hainan island, China. 2D NMR techniques such as mono and hetero-COSY, NOESY, COLOC as well as 1H-NMR line broadening effect were utilized for structure elucidation. The separation techniques, structure elucidations and bioassay results will be reported.

Animals↗