125 research outputs found
SESQUITERPENE LACTONES FROM PERITYLE EMORYI
Abstract-The extract of the aerial parts of Perityle emoryi gave, in addition to seven known sesquiterpene lactones, six new germacranolides and a guaianolide as well as a further thymol derivative together with several known ones and two labdanes. The structures were elucidated by high field 'H NMR spectroscopy. The chemotaxonomic aspects are discussed briefly
Effect of head size and rotation on taper corrosion in a hip simulator
Aims
This study investigates head-neck taper corrosion with varying head size in a novel hip simulator instrumented to measure corrosion related electrical activity under torsional loads.
Methods
In all, six 28 mm and six 36 mm titanium stem-cobalt chrome head pairs with polyethylene sockets were tested in a novel instrumented hip simulator. Samples were tested using simulated gait data with incremental increasing loads to determine corrosion onset load and electrochemical activity. Half of each head size group were then cycled with simulated gait and the other half with gait compression only. Damage was measured by area and maximum linear wear depth.
Results
Overall, 36 mm heads had lower corrosion onset load (p = 0.009) and change in open circuit potential (OCP) during simulated gait with (p = 0.006) and without joint movement (p = 0.004). Discontinuing gaitâs joint movement decreased corrosion currents (p = 0.042); however, wear testing showed no significant effect of joint movement on taper damage. In addition, 36 mm heads had greater corrosion area (p = 0.050), but no significant difference was found for maximum linear wear depth (p = 0.155).
Conclusion
Larger heads are more susceptible to taper corrosion; however, not due to frictional torque as hypothesized. An alternative hypothesis of taper flexural rigidity differential is proposed. Further studies are necessary to investigate the clinical significance and underlying mechanism of this finding
Potent cytotoxic effects of Calomeria amaranthoides on ovarian cancers
<p>Abstract</p> <p>Background</p> <p>Ovarian cancer remains the leading cause of death from gynaecological malignancy. More than 60% of the patients are presenting the disease in stage III or IV. In spite of combination of chemotherapy and surgery the prognosis stays poor for therapy regimen.</p> <p>Methods</p> <p>The leaves of a plant endemic to Australia, <it>Calomeria amaranthoides</it>, were extracted and then fractionated by column chromatography. <it>In vitro </it>cytotoxicity tests were performed with fractions of the plant extract and later with an isolated compound on ovarian cancer cell lines, as well as normal fibroblasts at concentrations of 1-100 Όg/mL (crude extract) and 1-10 Όg/mL (compound). Cytotoxicity was measured after 24, 48 and 72 hours by using a non-fluorescent substrate, Alamar blue.</p> <p><it>In vivo </it>cytotoxicity was tested on ascites, developed in the abdomen of nude mice after inoculation with human OVCAR<sub>3 </sub>cells intraperitoneally. The rate of change in abdomen size for the mice was determined by linear regression and statistically evaluated for significance by the unpaired t test.</p> <p>Results</p> <p>Two compounds were isolated by chromatographic fractionation and identified by <sup>1</sup>H-NMR, <sup>13</sup>C-NMR and mass spectrometry analyses, EPD, an α-methylene sesquiterpene lactone of the eremophilanolide subtype, and EPA, an α-methylene carboxylic acid.</p> <p>Cytotoxicity of EPD for normal fibroblasts at all time points IC<sub>50 </sub>was greater than 10 Όg/mL, whereas, for OVCAR<sub>3 </sub>cells at 48 hours IC<sub>50 </sub>was 5.3 Όg/mL (95% confidence interval 4.3 to 6.5 Όg/mL).</p> <p>Both, the crude plant extract as well as EPD killed the cancer cells at a final concentration of 10 Όg/mL and 5 Όg/mL respectively, while in normal cells only 20% cell killing effect was observed. EPA had no cytotoxic effects.</p> <p>Changes in abdomen size for control versus Cisplatin treated mice were significantly different, P = 0.023, as were control versus EPD treated mice, P = 0.025, whereas, EPD versus Cisplatin treated mice were not significantly different, P = 0.13.</p> <p>Conclusions</p> <p>For the first time both crude plant extract from <it>Calomeria amaranthoides </it>and EPD have been shown to have potent anti-cancer effects against ovarian cancer.</p
Mono- versus polyaxial locking plates in distal femur fractures â a biomechanical comparison of the Non-Contact-Bridging- (NCB) and the PERILOC-plate
The effect of isolates from 'Cassipourea flanaganii' (Schinz) alston, a plant used as a skin lightning agent, on melanin production and tyrosinase inhibition
Ethnopharmacological relevance
The Zulu and Xhosa people of South Africa use the stem bark of Cassipourea flanaganii as a skin-lightning cosmetic.
Aim of the study
To isolate and identify compounds responsible for the skin lightning properties from the stem bark of Cassipourea flanaganii and to evaluate their cytotoxicity towards skin cells.
Materials and methods
Extracts from the stem bark of Cassipourea flanaganii were isolated using chromatographic methods and structures were determined using NMR, IR and MS analysis. The tyrosinase inhibitory activity and the ability to inhibit the production of melanin were determined using human primary epidermal melanocyte cells. Cytoxicity was established using the same melanocytes and a neutral red assay.
Results
One previously undescribed compound, ent-atis-16-en-19-al (1) along with the known ent-atis-16-en-19-oic acid (2), ent-atis-16-en-19-ol (3), ent-kaur-16-en-19-oic acid (4), ent-kaur-16-en-19-al (5), ent-manoyl oxide (6), guinesine A (7), guinesine B (8), guinesine C (9), lichenxanthone (10), 2,4-dihydroxy-3,6-dimethyl benzoic acid methyl ester (11), lynoside (12), lupeol (13), ÎČ-amyrin (14), docosyl ferulate (15), stigmasterol, sitosterol and sitosterol-O-glucoside were isolated in this investigation. An impure fraction containing compound 3 was acetylated to obtain 19-acetoxy-ent-atis-16-ene (3a). Compounds 10 and 11 are usually isolated from lichen, hence they are possible contaminants of lichen harvested with the bark. Compounds 1, 3a, 5â14 were not significantly cytotoxic to the primary epidermal melanocyte cells (P > 0.05) when compared to the negative and positive controls (DMSO, 0.1% and hydrogen peroxide, 30 wt% in water). Inhibition of tyrosinase was significantly greater with respect to the negative control (P < 0.001) for compounds 3a, 5â8 and 9â10 at 10 ÎŒM and for compounds 5â8 and 9â10 at 100 ÎŒM. Compared to hydroquinone (the positive control) at 10 ÎŒM, the level of inhibition was comparable or to that of compounds 3a, 5, 6, and 8â10 at 10 ÎŒM, with 9 and 10 showing a greater level of inhibition. Inhibition of melanin was both concentration and time dependent for all compounds tested with higher melanin content at 24 h compared to 48 h s and at 10 mM compared to100 mM at both time points; melanin content was significantly lower for hydroquinone at both time points and concentrations.
Conclusions
Compounds 1, 5â14, isolated from Cassipourea flanaganii and the derivative 3a showed low cytotoxicity. All compounds had a clear time and concentration dependent effect on melanin content which did not appear to be dependent on their inhibition of tyrosinase
Atividade antiproliferativa e mutagĂȘnica dos extratos aquosos de Baccharis trimera (Less.) A. P. de Candolle e Baccharis articulata (Lam.) Pers. (Asteraceae) sobre o sistema teste de Allium cepa
An unusual dimeric sesquiterpene and other constituents from Chilean Baccharis species
The aerial parts of B. santelicis afforded several known furoclerodanes and phenolics. In addition to known compounds an unusual dimeric sesquiterpene and five labdane derivatives were isolated from B. petiolata. The structures were elucidated by high field NMR techniques and a few chemical transformations. © 1991
A heliangolide, 3-hydroxyumbelliferone derivatives and diterpenes from Bahia ambrosioides
The aerial parts of Bahia ambrosioides afforded several germacranolides and heliangolides one of which has not been reported previously. Furthermore, in addition to widespread compounds, four 3-hydroxyumbelliferone derivatives were present as well as two new diterpenes, an ent-kaurane diol and an ent-rosane diol. The structures were elucidated by high field NMR spectroscopy. The chemotaxonomic aspects are discussed briefly. © 1990
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