Managing trust in peer-to-peer systems using reputation-based techniques

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)27622-1

Determination of aconitine-type alkaloids as markers in fuzi (Aconitum carmichaeli) by LC/(+)ESI/MS3

LC/(+)ESI/MS3 was used to determine aconitine, mesaconitine, and hypaconitine as target markers in crude methanol extracts of (i) the raw lateral roots of Aconitum carmichaeli, (ii) roots treated by three different refining processes, and (iii) eight generally available traditional Chinese medicine (TCM) preparations containing fuzi (treated lateral roots of A. carmichaeli). The optimal ionization behavior resulted when using electrospray ionization (ESI) in positive-ion mode with 0.005% TFA as an additive in the mobile phase. The consecutive reaction monitoring(CRM) mode provided additional improvements in selectivity, which was exploited to minimize the noise and interference problems. Employing this approach, aconitine and mesaconitine were found to decompose readily during the refining processes, but hypaconitine remains present at the same content, presumably because of its characteristic chemical Structure. Thus, treated and untreated fuzi samples can be distinguished by monitoring the ratio of aconitine and mesaconitine to hypaconitine. The limits of detection (LODs) for these three markers were 0.05, 0.08, and 0.03 ng/ml. The linearity range for the three marker compounds was 0.1-1000 ng/ml. The analysis time was 12 min per sample. (C) 2008 Elsevier B.V. All rights reserved

Supercritical carbon dioxide extraction of triglycerides from Aquilaria crassna seeds

This study examines the effects of pressure, temperature and solvent to solid ratio (SSR) on extraction efficiency of triglycerides from powdered Aquilaria crassna seeds by using supercritical carbon dioxide (SC-CO(2)) extraction. Supercritical extractions were designed for pressures ranging from 250 to 350 bar, temperatures ranging from 313 to 333 K and SSR values ranging from 60:1 to 120:1. All values were selected using response surface methodology (RSM) in order to determine their effects on the concentration of triglycerides from the SC-CO(2) extracted oil. Using 3000 g of carbon dioxide over 4 h, a supercritical carbon dioxide extraction (at 310 bar, 333 K and an SSR value of 100:1) yielded 33.99% oil having the concentration of triglycerides of 568.3 mg/g. The extraction efficiency (i.e. recovery) of triglycerides reached 96.77%. Changes in pressure presented more effective in increasing the recovery of triglycerides. Both temperature and the SSR value are important in obtaining high concentration of triglycerides from the A. crassna seeds that are potential for biodiesel materials. (C) 2010 Elsevier B.V. All rights reserved

Isolation and Cytotoxicity of the Lignanoids from Chamaecyparis formosensis

In this study, we assessed the antitumor activity of the methanol extract from wood chips of the heartwood of the Taiwan red cypress, Chamaecyparis formosensis Matsumura, which is a precious tree species endemic to Taiwan. A brine shrimp lethality test (BST) indicated that the ethyl acetate (EtOAc)-soluble extract from the MeOH extract was a suitable candidate (LC(50) = 15.36 mu g/mL) for further studies of the antitumor activity of its components. From this EtOAc fraction, we isolated six lignans and two norlignans and tested their cytotoxic activities in vitro against promyelocytic leukemia (HL-60) and hepatoma (Hepa-G2) cell lines. Among these compounds, 7,7' (S)-dihydrotaiwanin C, isolated for the first time from nature, with its single crystal Structure depicted in this study, exhibited significant cytotoxic activity against HL60 cell lines in vitro (IC(50) = 4.03 mu g/mL) after 24 hours

Extraction and purification of flavanone glycosides and kaemferol glycosides from defatted Camellia oleifera seeds by salting-out using hydrophilic isopropanol

The purpose of this research was to investigate a salting-out procedure for isolating four flavonoid glycosides from defatted Camellia oleifera seeds. The procedure included extraction with 80% methanol, methanol removal and addition of an equal amount of hydrophilic isopropanol and salt to separate the isopropanol fraction from the water layer. Using successive column chromatography, kaemferol-3-O-[2-O-beta-D-glucopyransoyl-6-O-alpha-L-rhamnopyranosyl]-beta-D-glucopyranoside (compound 1), kaemferol-3-O-[2-O-beta-D-xylopyranosyl-6-O-alpha-L-rhamnopyranosyl]-beta-D-glucopyranoside (compound 2), naringenin-7-O-[beta-D-xylopyranosyl(1 -> 6)][beta-D-glucopyranosyl(1 -> 3)-alpha-L-rhamnopyranosyl(1 -> 2)]-beta-D-glucopyranoside (compound 3) and naringenin-7-O-beta-D-xylopyranosyl(1 -> 6)-beta-D-glucopyranoside (compound 4) were obtained. The structure of compound 3, a new flavanone glycoside, was analyzed using UV, FT-IR, (1)H NMR, (13)C NMR and HR-FAB-MS. Quantification using high-performance liquid chromatography (HPLC) demonstrated that defatted C. oleifera seed cake contains 7.92, 17.7, 2.23 and 1.06 mg/g of the four compounds. The extraction efficiencies of the four compounds were increased by 23.17%, 7.59%, 48.67% and 47.22% from those obtained with n-butanol partition extraction. This new extraction technique is simpler, faster and less expensive than the traditional extraction method. Accordingly, this salting-out method can potentially replace the existing one. (C) 2009 Elsevier B.V. All rights reserved

LC-APCI-MS method for detection and analysis of tryptanthrin, indigo, and indirubin in Daqingye and Banlangen

A rapid, selective, and sensitive LC-APCI-MS method is developed in this study for detecting and analyzing tryptanthrin, indigo, and indirubin in Daqingye and Banlangen, which are, respectively, the leaves and roots of Isatis indigotica and Strobilanthes cusia in traditional Chinese medicine. The detection of the three active components is linear in concentrations ranging from 100 to 1500 ng/mL, the squared correlation coefficient is higher than 0.996, the precision as measured by the relative standard deviation is no larger than 9.5%, and the recovery is greater than 86.6%. The analysis of the 21 Banlangen samples led to considerably different conclusions on the contents of tryptanthrin, indigo, and indirubin in fresh leaves versus those in dried leaves. These results should shed some light on future plant selection and breeding. Compared with the traditional TLC and HPLC-UV methods, the new LC-APCI-MS approach has proven to be an optimal tool for detecting and analyzing the three marker compounds in the Chinese herbal medicines of Daqingye and Banlangen. (c) 2006 Elsevier B.V. All rights reserved

Quality control of Chinese medicinal preparations LC/ESI(+)/MS/MS analyses of saikosaponins-a and -c as markers of Bupleuri radix samples

We have used LC/ion trap tandem MS analysis to determine saikosaponin-a and -c as target markers in crude 70% methanol extracts from three different species of Bupleuri radix and the 10 most-popular Chinese medicinal preparations containing "Chaihu" (B. radix) without any clean-up. The optimal ionization characteristics were obtained when using positive-ion electrospray ionization (ESI) with 50 mu M sodium acetate as an additive in the mobile phase. We observed good linearity over the range from 0.02 to 2 mu g/ml for saikosaponin-a and from 0.02 to 1 mu g/ml for saikosaponin-c. The intra-day precisions varied between 3.3 and 8.8% for saikosaponin-a and 0.3 and 11.1% for saikosaponin-c. The limits of detection were 0.01 mu g/ml for both markers. The recoveries of saikosaponin-a and -c from the extract of a medicinal preparation sample (Chai-Hu-Ching-Gan-Tang, No. 13 in the table of section Analysis on actual samples) were 97 and 100%, respectively, at a 1 mu g/ml spiking concentration of each marker. The highest concentrations of saikosaponin-a and -c among the three B. radixes were found in B. kaoi Liu Chao & Chuang (10.1 mg/g) and in B. falcatum (3.4 mg/g), respectively. The amounts of these saikosaponins in the 10 Chinese medicinal preparations ranged between 0.11 and 1.22 mg/g for saikosaponin-a and between 0.01 and 0.33 mg/g for saikosaponin-c. (c) 2006 Elsevier B.V. All rights reserved