Biomedical subjects

Xiao-Li Li

Publications and source records attributed to Xiao-Li Li.

17 recordsLinked to original sources

PubMed2007

Przewalskin B, a novel diterpenoid with an unprecedented skeleton from Salvia przewalskii maxim.

Przewalskin B (1), a novel diterpenoid possessing a unique skeleton, was isolated from a Chinese medicinal plant Salvia przewalskii. Its structure and relative stereochemistry were elucidated by extensive NMR analysis and a single-crystal X-ray study. A possible biosynthetic pathway for 1 was proposed. Compound 1 exhibited modest anti-HIV-1 activity with EC50 = 30 microg/mL. [structure: see text].

Anti-HIV Agents↗

PubMed2006

Systematic gene function prediction from gene expression data by using a fuzzy nearest-cluster method.

BACKGROUND: Quantitative simultaneous monitoring of the expression levels of thousands of genes under various experimental conditions is now possible using microarray experiments. However, there are still gaps toward whole-genome functional annotation of genes using the gene expression data. RESULTS: In this paper, we propose a novel technique called Fuzzy Nearest Clusters for genome-wide functional annotation of unclassified genes. The technique consists of two steps: an initial hierarchical clustering step to detect homogeneous co-expressed gene subgroups or clusters in each possibly heterogeneous functional class; followed by a classification step to predict the functional roles of the unclassified genes based on their corresponding similarities to the detected functional clusters. CONCLUSION: Our experimental results with yeast gene expression data showed that the proposed method can accurately predict the genes' functions, even those with multiple functional roles, and the prediction performance is most independent of the underlying heterogeneity of the complex functional classes, as compared to the other conventional gene function prediction approaches.

Algorithms↗

PubMed2006

Przewalskin A: A new C23 terpenoid with a 6/6/7 carbon ring skeleton from Salvia przewalskii maxim.

Przewalskin A (1), a novel C23 terpenoid with a 6/6/7 carbon ring skeleton, was isolated from Salvia przewalskii. Its structure was determined by comprehensive 1D NMR, 2D NMR, and MS spectroscopic analysis and subsequently confirmed by a single-crystal X-ray diffraction study of its PDC oxidation derivative (2). Compounds 1 and 2 showed modest anti-HIV-1 activity with EC50 = 41 and 89 microg/mL, respectively.

Carbon↗

PubMed2006

Anti-osteoporotic effect of Erythrina variegata L. in ovariectomized rats.

The present study was designed to investigate whether Erythrina variegata L. (EV), which belongs to the leguminous family, exerted any beneficial effects on bone in ovariectomized rats. Daily oral administration of the EV extract at 300 and 600 mg/kg for 14 weeks to rats prevented the OVX-induced increase in the serum OCN, ALP, and urinary DPD levels. Histomorphometric analysis of the proximal end of the tibia showed that the EV extract prevented the estrogen deficiency-induced decrease in trabecular thickness and trabecular area, as well as restoring the increase in trabecular separation in a dose-dependent manner. Moreover, the EV extract improved the energy absorption and stiffness of the mid-shaft of the rat femur. Thus, the present study clearly demonstrated that EV could suppress the high rate of bone turnover induced by estrogen deficiency, inhibit bone loss and improve the biomechanical properties of bone in the OVX rats.

Animals↗

PubMed2006

Dichotomains A and B: two new highly oxygenated phenolic derivatives from Dicranopteris dichotoma.

[structure: see text] Dichotomains A (1) and B (2), two new highly oxygenated phenolic derivatives that feature a spirodilactone moiety in their structures, were isolated from the fronds of Dicranopteris dichotoma. Their structures were elucidated on the basis of NMR and MS spectroscopic data, and the stereochemistry of 1 was finally determined by single-crystal X-ray diffraction. Compound 2 showed weak anti-HIV-1 activity.

Anti-HIV Agents↗

PubMed2006

Sphenadilactones A and B, two novel nortriterpenoids from Schisandra sphenanthera.

[structure: see text] Two novel nortriterpenoid compounds, sphenadilactones A (1) and B (2), have been isolated from the leaves and stems of Schisandrasphenanthera. The structural elucidation of 1 and 2 was accomplished by extensive NMR analysis. The relative stereochemistry of 1 was established by single-crystal X-ray crystallography. Both compounds were tested for their cytotoxicities against K562, A549, and HT-29, and compound 1 was further tested for its anti-HIV-1 activity.

Anti-HIV Agents↗

PubMed2006

Rubriflordilactones A and B, two novel bisnortriterpenoids from Schisandra rubriflora and their biological activities.

Rubriflordilactones A (1) and B (2), two novel highly unsaturated rearranged bisnortriterpenoids possessing a biosynthetically modified aromatic D-ring, were isolated from the leaves and stems of Schisandra rubriflora. Their structures were established on the basis of extensive spectroscopic methods, including two-dimensional NMR techniques, and confirmed by X-ray crystallographic analysis. Compound 1 showed weak anti-HIV-1 activity, and compound 2 exhibited an EC50 value of 9.75 microg/mL (SI=12.39) against HIV-1 replication with low cytotoxicity.

Anti-HIV Agents↗

PubMed2006

Nortriterpenoids from Schisandra lancifolia.

Six new nortriterpenoids, lancifodilactones I-N (1-6), as well as nine known ones, were isolated from the leaves and stems of Schisandra lancifolia. Their structures were elucidated on the basis of spectroscopic methods including 2D NMR analysis, and the structures of compounds 1 and 4 were further confirmed by single-crystal X-ray crystallography. In addition, all new compounds were tested for anti-HIV-1 activity.

Anti-HIV Agents↗

PubMed2006

Taxoids from Taxus chinensis.

Two new taxoids, 13,15-epoxy-13-epi-taxayunnasin A (1) and taxchinin N (2), were isolated from the leaves and stems of Taxus chinensis. Compound 2 is the first taxoid to be reported with an alpha,beta-unsaturated lactone at C-4, C-5, C-20, and C-2. The structure of 1 was elucidated by spectroscopic analysis and confirmed by semisynthesis from taxayunnasin A, while 2 was determined structurally using spectroscopic methods and by single-crystal X-ray diffraction.

Crystallography, X-Ray↗

PubMed2006

Two new abietane diterpenoids from Salvia yunnanensis.

Two new abietane diterpenoids, yunnannin A and danshenol C, were isolated from Salvia yunnanensis together with ten known diterpenoids, danshenol A, przewalskin, tanshinone IIA, tanshinone I, crypotanshinone, 1,2-dihydrotanshinone, tanshinlactone, 5,6-dehydrosugiol, 12-hydroxy-6,7-seco-8,11,3-abietatriene-6,7-dial and phytol. Their structures were established based on spectroscopic data, chemical reactions and comparison with literature data. Compounds were tested for their antitumor activity in T-24, QGY, K562, Me180 and BIU87 cell lines. Compound showed inhibited growth of K562 (IC50=0.53 microg/mL), T-24 (IC50=7.94 microg/mL), QGY (IC50=4.65 microg/mL) and Me180 (IC50=6.89 microg/mL) cell lines while compound was inactive. Compound showed moderate inhibitory activity on QGY (IC50=16.75 microg/mL) and Me180 (IC50=5.84 microg/mL) cells.

Abietanes↗

PubMed2006

[Research of kingsbrain on improving the learning and memory ability of MCAO rats].

OBJECTIVE: To explore the influence of Kingsbrain (GETO) on the learning memory impairment of rats with cerebral ischemia. METHOD: Rats with cerebral ischemia were administered GETO orally once a day for one month. The ability of spatial-learning memory of rats was evaluated by Morris Water Maze (MWM). Duxil was used as a positive control. RESULT: the results of place navigation of MWM showed that at the 3rd time of swimming training, the escape latency of rats of the GETO group, Duxil group and Sham group were shorter than that of model group. The escape latency were (54.1 +/- 43.94), (55.9 +/- 43.49), (50.4 +/- 34.99) and (85.4 +/- 42.8) s, respectively; but there was no significantly difference. After the 6th time of swimming training, the escape latency of rats of the GETO group (37.8 +/- 38.69) s, the Duxil group (37.4 +/- 38.03) s and the sham group (26.9 +/- 21.63) s were significantly shorter than that of model rats (77.5 +/- 47.59) s, P < 0.05, respectively. Comparison of the swimming distance among groups were similar to the escape latency among groups. In the test of spatial probe, results of the ratio of the swimming time of platform quadrant (tP) vs the total swimming time (tT) and the ratio of the swimming distance of platform quadrant (dP) vs the total swimming distance (dT) indicated that the ratios of the GETO group (0.347 +/- 0.0662, 0.344 +/-0.055 1), the Duxil group (0.345 +/- 0.0984, 0.34 +/- 0.0934) and the sham group (0.35 +/- 0.0662, 0.349 +/- 0.0589) were significantly higher than those of the Model group (0.261 +/- 0.0689, 0.274 +/- 0.0544), P < 0.05, respectively. CONCLUSION: GETO can significantly improve the spatial learning and memory ability of rats with cerebral ischemia, which provides the pharmacodynamics evidence for its clinical application of improveing the learning and memory ability in poststroke patients.

Animals↗

PubMed2006

[Discrimination of varieties of apple using near infrared spectra based on principal component analysis and artificial neural network model].

A new method for the discrimination of varieties of apple by means of near infrared spectroscopy (NIRS) was developed. First, principal component analysis (PCA) was used to compress thousands of spectral data into several variables and describe the body of spectra, the analysis suggested that the cumulate reliabilities of PC1 and PC2 (the first two principle components) were more than 98%, and the 2-dimentional plot was drawn with the scores of PC1 and PC2. It appeared to provide the best clustering of the varieties of apple. The loading plot was drawn with PC1 and PC2 through the whole wavelength region. The fingerprint spectra, which were sensitive to the variety of apple, were obtained from the loading plot. The fingerprint spectra were applied as ANN-BP inputs. Seventy five samples from three varieties were selected randomly, then they were used to build discrimination model. This model was used to predict the varieties of 15 unknown samples; the distinguishing rate of 100% was achieved. This model is reliable and practicable. So the present paper could offer a new approach to the fast discrimination of varieties of apple.

Malus↗

PubMed2005

Lancifodilactone F: a novel nortriterpenoid possessing a unique skeleton from Schisandra lancifolia and its anti-HIV activity.

[structures: see text] Lancifodilactone F (1), possessing an unprecedented rearranged pentanortriterpenoid backbone derived from cycloartane, was isolated from the leaves and stems of Schisandra lancifolia (Rehd. et Wils) A. C. Smith. Its structure was established by comprehensive NMR and MS spectroscopic analysis, coupled with single-crystal X-ray experiment. Compound 1 exerted minimal cytotoxicity against C8166 cells (CC50 > 200 microg/mL) and showed anti-HIV activity with EC50 = 20.69 +/- 3.31 microg/mL and a selectivity index > 6.62.

Anti-HIV Agents↗

PubMed2005

[Cardiovascular disease in Chinese chronic renal insufficiency patients-epidemiology survey].

OBJECTIVE: Cardiovascular (CV) disease (CVD) is the single most important cause of death among Chinese dialysis patients, accounting for 51% of overall mortality. The study was performed to investigate the prevalence and the spectrum of CVD in Chinese chronic kidney disease (CKD) patients. METHODS: The multicenter Chinese cohort study examined 1239 CKD patients from 7 main medical centers (distributed in 5 regions of China) who were hospitalized between 2002 and 2003. RESULTS: (1) The most prevalent pathological form of CVD was left ventricular (LV) hypertrophy (LVH), accounting for 58.5% of total patients. The prevalence of coronary artery disease (CAD), congestive heart failure (CHF), and cerebrovascular accidents (CVA) was 16.5%, 27.7% and 5.6%, separately. (2) The cohort with minor renal dysfunction (stage 2-3) had higher prevalence of CAD (5.9%) and CVA (1.0%) compared with general population in the same regions. Up to 41.2% of minor CKD patients were complicated with LVH, and 13.8% of them had clinical evidence of CHF. The prevalence of CAD, LVH and CHF increased as glomerular filtration decline. (3) The prevalence of CAD (20.0%) was much lower and the prevalence of CVA (5.4%) was higher in Chinese dialysis patients than that in American dialysis population. There was significant geographical variations in CAD prevalence, but it was not different between genders. CONCLUSION: The CV risk is significantly increased in patients with CKD. Even minor CKD has a major impact on the CV risk. The prevalence of CAD in Chinese dialysis patients is markedly lower than that in American dialysis population.

Adult↗

PubMed2005

Two new icetexane diterpenoids from Salvia przewalskii.

Two new icetexane diterpenoids, przewalskin C, D (1, 2), together with sixteen known diterpenoids, were isolated from Salvia przewalskii. Eight of known ones (compounds 3, 12-18) were reported firstly from this plant. To the best of our knowledge, it's the first report of icetexane diterpenoids from this plant. The identification and structural elucidation of these compounds were based on 1D- and 2D-NMR spectral data analysis.

Diterpenes↗

PubMed2005

Interaction graph mining for protein complexes using local clique merging.

While recent technological advances have made available large datasets of experimentally-detected pairwise protein-protein interactions, there is still a lack of experimentally-determined protein complex data. To make up for this lack of protein complex data, we explore the mining of existing protein interaction graphs for protein complexes. This paper proposes a novel graph mining algorithm to detect the dense neighborhoods (highly connected regions) in an interaction graph which may correspond to protein complexes. Our algorithm first locates local cliques for each graph vertex (protein) and then merge the detected local cliques according to their affinity to form maximal dense regions. We present experimental results with yeast protein interaction data to demonstrate the effectiveness of our proposed method. Compared with other existing techniques, our predicted complexes can match or overlap significantly better with the known protein complexes in the MIPS benchmark database. Novel protein complexes were also predicted to help biologists in their search for new protein complexes.

Algorithms↗

PubMed2004

[Study on configuration fabric and germinative conditions of Salvia miltiorrhizy seeds].

OBJECTIVE: To provide theoretic warrant and technical reference for Salvia miltiorrhizr standardization planting, by carrying out various systemic studies such as observation of seeds configuration fabric, idiosyncrasy of water absorption and groping germinating conditions. METHOD: In the study of configuration fabric, seeds were observed and taken photos by scanning electronic microscope, and heft method was used for measuring changes of water absorption velocity and dehydration velocity. Seeds germination conditions were probed into under the national test regulations for crop seeds and related prescription from international standards. RESULT: (1) There was a layer of slime about 10-20 microm thickness covering epicarp of Danshen seeds. The slime formed as diamond meshwork (reseau) and the weight of it was 8%-10% of total seeds weight. (2) The speed of water absorption of seeds was extremely rapid. The weight of seeds could increase above 10 times as original while the dehydration velocity was quite low. (3) The optimal temperature for the seeds germination is around 25 degrees C, and the germination rate of the new seeds gained yearly was above 75%, but the rate would decrease sharply as years went by. It was also found that the seeds germination power and exponent of vigor were quite high under the temperature transformation between 23 degrees C, 28 degrees C. Such treatments as pre-cool, PEG treatment and infusing with GA3 could increase the rate of seeds germination capacity obviously.

Germination↗