Several C-8 long-chain fatty acid esters of aconitine-type norditerpenoid alkaloids namely, aconitine, delphinine, delphisine, falconerine-8-acetate, mesaconitine, and pseudaconitine bearing a C-8 ...acetyl group, have been prepared. Preparation was achieved by heating the alkaloids with the neat fatty acid under vacuum. All the compounds have been fully characterized by physical and spectroscopic data. Identification and characterization of reaction byproducts are also included.
The main objective of this research is to develop a photosensitive supramolecular assembly by incorporating a photochromic compound into the lipid bilayer of a liposome. Photoinduced changes in the ...structure of this compound was expected to affect the membrane permeability of liposome to afford selective release of encapsulated compounds. A photochromic compound, 1,2-bis(2-methyl-5-phenyl-3-thienyl) perfluorocyclopentene (1) was synthesized. The inclusion of 1 in a lipid bilayer of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and conservation of its photochromism were studied using differential scanning calorimetry (DSC) and absorption spectroscopy, respectively. From our DSC studies, a slight decrease of Tm and increase of ΔT 1/2 were observed with increasing concentration of 1 in DPPC multilamellar vesicles (MLVs). Compared to MLVs of pure DPPC, a shift of the pretransition to lower temperature and its relative disappearance were observed for MLV samples containing 1. These results suggest that 1 is located in the C2-C8 methylene region of the lipid hydrocarbon chains. To study changes in membrane permeability, a fluorophore-quencher pair, 8-hydroxypyrene-1,3,6-trisulfonic acid and p-xylene-bis-pyridinium bromide (HPTS-DPX) was encapsulated inside large unilamellar vesicles (LUVs) composed of DPPC. Membrane permeability was correlated with an increase in the emission of HPTS as it diffuses from the interior of the liposome into bulk aqueous solution where it is relatively free from quenching. In these studies, DPPC containing 1 and HPTS with its controls at a mole ratio of 1:DPPC at 1:3 were prepared. The irradiation studies were performed by photocycling 1 between the opened (1o ) and closed (1c) ring isomers with exposure to ultraviolet (UVA) and visible (Vis) light. The net change in fluorescence intensity of HPTS due solely to isomerization of 1 in lipid bilayer was determined after a series of corrections and comparisons with the controls. In addition, the percentage release of HPTS was calculated based on the 100% release of encapsulated HPTS, which was determined by the addition of a lipid soluble surfactant Triton X-100 to lyse the liposome membrane. From these studies, an increase in the fluorescence intensity of HPTS was not observed. As a result, we conclude that the photoisomerization of 1 does not have a large effect on the membrane permeability of DPPC LUVs. In addition, the large standard deviations suggest that we are approaching the detection limits of our experimental setup. One possible reason for why significant increases in membrane permeability were not observed is that the size of 1 is relatively small compared to the thickness of bilayer. As well, without a complementary lipid structure, 1 may lack the well-defined organization within the span of bilayer that would lead to a larger disruption in the local lipid order. In addition, the change in molecular structure accompanying the isomerization of 1 is potentially not large enough to disrupt the packing of the lipids within the bilayer, which may be necessary for large changes in membrane permeability.
Alpine wetlands in the Lhasa River Basin, China Zhang, Yili; Wang, Chunlian; Bai, Wanqi ...
Journal of Geographical Sciences/Journal of geographical sciences,
06/2010, Volume:
20, Issue:
3
Journal Article
Peer reviewed
Open access
The Lhasa River Basin is one of the typical distribution regions of alpine wetlands on the Tibetan Plateau. It is very important to get a better understanding of the background and characteristics of ...alpine wetland for monitoring, protection and utilization. Wetland construction and distribution in the basin were analyzed based on multi-source data including field investigation data, CBERS remote sensing data and other thematic data provided by 3S technology. The results are （1） the total area of wetlands is 209,322.26 hm^2, accounting for 6.37% of the total land area of the basin. The wetlands are mainly dominated by natural wetland, with artificial wetland occupying only 1.09% of the wetland area; marsh wetland is the principal part of natural wetland, dominated by Kobresia littledalei swampy meadow which is distributed in the river source area and upstream of Chali, Damshung and Medro Gongkar counties. The ratio and type of wetlands in different counties differ significantly, which are widely distributed in Chali and Damshung counties （accounting for 62% of the total wetland area）. （2） The concentrated vertical distribution of wetlands is at an elevation of 3600-5100 m The wetlands are widely distributed throughout the Yarlung Zangbo River Valley from river source to river mouth into the Yarlung Zangbo River. Marsh wetland is dominant in the source area and upstream of the river, with the mosaic distribution of lakes, Kobresia litUedalei and Carex moorcroftii swampy meadow, shrubby swamp and river; as for the middle-down streams, the primary types are river wetland and flooded wetland. The distribution is in a mosaic pattern of river, Kobresia humilis and Carex moorcroftii swampy meadow, Phragmites australis and subordinate grass marsh, flooded wetland and artificial wetland.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Based on the GIMMS AVHRR NDVI data （8 km spatial resolution） for 1982-2000, the SPOT VEGETATION NDVI data （1 km spatial resolution） for 1998-2009, and observa- tional plant biomass data, the CASA ...model was used to model changes in alpine grassland net primary production （NPP） on the Tibetan Plateau （TP）. This study will help to evaluate the health conditions of the alpine grassland ecosystem, and is of great importance to the pro- motion of sustainable development of plateau pasture and to the understanding of the func- tion of the national ecological security shelter on the TP. The spatio-temporal characteristics of NPP change were investigated using spatial statistical analysis, separately on the basis of physico-geographical factors （natural zone, altitude, latitude and longitude）, river basin, and county-level administrative area. Data processing was carried out using an ENVI 4.8 platform, while an ArcGIS 9.3 and ANUSPLIN platform was used to conduct the spatial analysis and mapping. The primary results are as follows： （1） The NPP of alpine grassland on the TP gradually decreases from the southeast to the northwest, which corresponds to gradients in precipitation and temperature. From 1982 to 2009, the average annual total NPP in the TP alpine grassland was 177.2x1012 gC yrl（yr represents year）, while the average annual NPP was 120.8 gC m^-2 yr^-1. （2） The annual NPP in alpine grassland on the TP fluctuates from year to year but shows an overall positive trend ranging from 114.7 gC m^-2 yr^-1 in 1982 to 129.9 gC m^-2 yr^-1 in 2009, with an overall increase of 13.3%; 32.56% of the total alpine grassland on the TP showed a significant increase in NPP, while only 5.55% showed a significant decrease over this 28-year period. （3） Spatio-temporal characteristics are an important control on an- nual NPP in alpine grassland： a） NPP increased in most of the natural zones on the TP, only showing a slight decrease in the Ngari montane desert-steppe and desert zone. The positive trend in NPP in the high-cold shrub-meadow zone, high-cold meadow steppe zone and high-cold steppe zone is more significant than that of the high-cold desert zone; b） with in- creasing altitude, the percentage area with a positive trend in annual NPP follows a trend of ＂increasing-stable-decreasing＂, while the percentage area with a negative trend in annual NPP follows a trend of ＂decreasing-stable-increasing＂, with increasing altitude; c） the varia- tion in annual NPP with latitude and longitude co-varies with the vegetation distribution; d） the variation in annual NPP within the major river basins has a generally positive trend, of which the growth in NPP in the Yellow River Basin is most significant. Results show that, based on changes in NPP trends, vegetation coverage and phonological phenomenon with time, NPP has been declining in certain places successively, while the overall health of the alpine grassland on the TP is improving.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Delphinium leroyi plants grown from seed of Tanzanian origin yielded six norditerpenoid alkaloids: the known compounds browniine, delcosine, delcosine 14-O-acetate, and deltatsine, and two new ones, ...leroyine and its 14-O-acetate whose structures were established by spectrometric methods.
The vegetative parts of Galega orientalis Lam. cv. Gale, being tested in Canada as a new cold-hardy fodder crop, were found to contain two hemiterpenoid guanidines: the know alkaloid smirnovine, and ...its previously unknown (Z)-4-hydroxy derivative. The synthesis of smirnovine picrate is also described for the first time. A sample of G. orientalis from Estonia yielded smirnovine in similar concentrations (0.2%). Although these levels are low, more research is required to confirm that the alkaloids in fodder galega do not pose a threat to livestock in Canada. Keywords: Galega orientalis; fodder galega; guanidines; smirnovine; (Z)-4-hydroxysmirnovine
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19.
N-Oxides of Some Norditerpenoid Alkaloids Bai, Yili; Desai, Haridutt K; Pelletier, S. William
Journal of natural products (Washington, D.C.),
06/1995, Volume:
58, Issue:
6
Journal Article
Peer reviewed
Eight new N-oxides 1-8 of the norditerpenoid alkaloids aconitine, ajacine, delphinine, delphisine, deltaline, heteratisine, lappaconitine, and N-deacetyllappaconitine have been prepared with ...m-chloroperbenzoic acid. The structures of these compounds were established on the basis of their spectroscopic data (1H, 13C, DEPT, COSY, HETCOR, and selective INEPT nmr experiments). The complete nmr chemical shift assignments for all eight N-oxides are reported. Table 2 shows the differences between the 13C-nmr shifts of the N-oxides compared with those of the parent alkaloids.
New extraction procedures are described for the isolation and purification of ranunculin, the glycoside in members of the buttercup family which, upon autolysis, yield the vesicant oil, ...protoanemonin. The procedures permit the efficient determination of ranunculin in plant extracts by normal phase HPLC. Ranunculin levels in plant tissue ranged from 1.5 to 19.9% on a dry matter basis. Of the 11 species examined, 5 were new detections of ranunculin in the Ranunculaceae. The glycoside was rapidly hydrolyzed at room temperature in the presence of β-glucosidase as shown by HPLC of the reaction mixture. Autolysis occurred in aqueous acetone extracts at room temperature but not at −5 °C. Autolysis also occurred during cryogenic storage of plant tissue. Having extracted ranunculin with conventional solvents in the absence of acid, the glycoside can now be accepted as the natural storage form of protoanemonin and not an artifact arising from acid extraction. Keywords: Ranunculin; HPLC; β-glucosidase; aglycon; buttercup
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