Search results for "Rite"
showing 10 items of 2726 documents
Biologically-induced transition of bio-silica sol to mesoscopic gelatinous flocs: a biomimetic approach to a controlled fabrication of bio-silica str…
2012
Siliceous sponges form their skeletal elements, the spicules, enzymatically via the sponge-specific enzyme silicatein. The enzymatic product of silicatein in vitro is a bio-silica polymer that is not processed/hardened by phase separation. In the present study we applied a two-phase system to investigate the transition of bio-silica, formed by silicatein, from the lucid state to the opaque/turbid state. We report for the first time that the polyether polyethylene glycol [PEG] causes a rapid transition of the lucid bio-silica to the opaque/turbid state. For the experiments the recombinant silicatein from the demosponge Suberites domuncula had been used. This process is rapid (1 h) and procee…
Silintaphin-1 - interaction with silicatein during structure-guiding bio-silica formation
2011
Silicateins are unique enzymes of sponges (phylum Porifera) that template and catalyze the polymerization of nanoscale silicate to siliceous skeletal elements. These multifunctional spicules are often elaborately shaped, with complex symmetries. They carry an axial proteinaceous filament, consisting of silicatein and the scaffold protein silintaphin-1, which guides silica deposition and subsequent spicular morphogenesis. In vivo, the synthesis of the axial filament very likely proceeds in three steps: (a) assembly of silicatein monomers to form one pentamer; (b) assembly of pentamers to form fractal-like structures; and finally (c) assembly of fractal-like structures to form filaments. The …
ChemInform Abstract: Two New Triterpene Saponins from Acanthophyllum laxiusculum
2015
Two new triterpene glycosides, 1 and 2, together with three known ones, were isolated from roots of Acanthophyllum laxiusculum Schiman-Czeika. The structures of the new compounds were established by extensive 1D- and 2D-NMR spectroscopic experiments and MS analyses as 23-O-β-D-galactopyranosylgypsogenic acid 28-O-{β-D-glucopyranosyl-(1→2)-6-O-[4-carboxy-3-hydroxy-3-methyl-1-oxobutyl]-β-D-glucopyranosyl-(1→6)}-[β-D-glucopyranosyl-(1→3)]-β-D-galactopyranosyl ester (1) and gypsogenic acid 28-O-{β-D-glucopyranosyl-(1→2)-6-O-[4-carboxy-3-hydroxy-3-methyl-1-oxobutyl]-β-D-glucopyranosyl-(1→6)}-[β-D-glucopyranosyl-(1→3)]-β-D-galactopyranosyl ester (2).
Two New Triterpene Saponins from Cyclamen africanumBoiss. & Reuter
2012
Two new oleanane-type triterpene saponins, afrocyclamins A and B (1 and 2, resp.), were isolated from a MeOH extract of the roots of Cyclamen africanum Boiss. & Reuter, together with three known triterpenoid saponins, lysikokianoside, deglucocyclamin I, and its dicrotalic acid derivative. The structures were elucidated, on the basis of 1D- and 2D-NMR experiments and mass spectrometry as (3β,20β)-13,28-epoxy-16-oxo-3-{O-β-D-xylopyranosyl-(12)-O-β-D-glucopyranosyl-(14)-O-[β-D-glucopyranosyl-(12)]-α-L-arabinopyranosyl}oxy}oleanan-29-al (1) and (3β,16α,20β)-16,28,29-trihydroxy-olean-12-en-3-yl O-4-O-(4-carboxy-3-hydroxy-3-methyl-1-oxobutyl)-β-D-xylopyranosyl-(12)-O-β-D-glucopyranosyl-(14)-O-[β-…
A dammarane-type saponin from the roots of Ampelozizyphus amazonicus.
1993
A new C31 dammarane-type triterpenoid saponin has been isolated from the roots of Ampelozizyphus amazonicus. Its structure was elucidated to be ampelozigenin-15 alpha-O-acetyl- 3-O-alpha-L-rhamnopyranosyl-(1--2)-beta-D-glucopyranoside by 1D and 2D NMR spectroscopic methods, and by chemical transformations. Ampelozigenin is a novel triterpene, (20R,22R)-16 beta,22:16 alpha, 30-diepoxydammar-24(24')- methylene-3 beta, 15 alpha, 20-triol.
Bioactive saponins with cancer related and immunomodulatory activity: Recent developments
2005
Abstract Saponins are natural glycosides of steroid or triterpene which exhibited many different biological and pharmacological actions: e.g. immunomodulatory, antitumor, antiinflammatory, molluscicidal, antiviral, antifungal, hypoglycemic, hypocholesterolemic, to mention just a few. The aim of this summarize recent advances on the bioactivity of saponins related to cancer and immune system, which has attracted a great attention during the last five years
α-L-rhamnosidases: Old and New Insights
2007
L-Rhamnose is a component of plant cell wall pectic polysaccharides (Mutter et al., 1994; Ridley et al., 2001), glycoproteins (Haruko and Haruko, 1999) and secondary metabolites such as anthocyanins (Renault et al., 1997), flavonoids (Bar-Peled et al., 1991) and triterpenoids (Friedman and McDonald, 1997). It has also been found in bacterial heteropolysaccharides (Hashimoto and Murata, 1998), rhamnolipids (Ochsner et al., 1994) and in the repeating units of the O-antigen structure of the lipopolysaccharide component of bacterial outer membranes (Chua et al., 1999). Some rhamnosides are important bioactive compounds, e.g. cytotoxic saponins (Bader et al., 1998; Yu et al., 2002), antifungal p…
Triterpene saponins from Eryngium kotschyi
2015
Four new oleanane-type saponins 3-O-alpha-L-rhamnopyranosyl-(1 -> 4)-beta-D-glucuronopyranosyl-22-O-beta, beta-dimethylacryloylA1-barrigenol (1), 3-O-alpha-L-rhamnopyranosyl-(1 -> 4)-beta-D-glucuronopyranosyl-22-O-angeloylA1-barrigenol (2), 3-O-beta-D-glucopyranosyl-(1 -> 2)-[beta-D-glucopyranosyl-(1 -> 6)]-beta-D-glucopyranosyl-21,22,28-O-triacetyl-(3 beta,21 beta,22 alpha)-olean-12-en-16-one (3), and 3-O-beta-D-glucopyranosyl-(1 -> 2)-glucopyranosyl-22-O-beta-D-glucopyranosylsteganogenin (4), along with the known 3-O-beta-D-galactopyranosyl-(1 -> 2)-[alpha-L-arabinopyranosyl-(1 -> 3)]-beta-D-glucuronopyranosyl-22-O-angeloylA1-barrigenol and 3-O-alpha-L-rhamnopyranosyl-(1 -> 4)-beta-D-gluc…
Two new triterpene saponins from Eryngium campestre.
2005
Two new triterpene saponins, 3-O-beta-D-glucopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->4)]-beta-D-glucuronopyranosyl-22-O-angeloyl-R1-barrigenol (1) and 3-O-beta-D-glucopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->4)]-beta-D-glucuronopyranosyl-22-O-beta,beta-dimethylacryloyl-A1-barrigenol (2), were isolated from the roots of Eryngium campestre (Apiaceae). Their structures were established mainly by 2D NMR techniques and mass spectrometry.
Development of a Matrix-Matched Sphalerite Reference Material (MUL-ZnS-1) for Calibration of In Situ Trace Element Measurements by Laser Ablation-Ind…
2016
Sphalerite (ZnS) is an abundant ore mineral and an important carrier of elements such as Ge, Ga and In used in high-technology applications. In situ measurements of trace elements in natural sphalerite samples using LA-ICP-MS are hampered by a lack of homogenous matrix-matched sulfide reference materials available for calibration. The preparation of the MUL-ZnS1 calibration material containing the trace elements V, Cr, Mn, Co, Ni, Cu, Ga, Ge, As, Se, Mo, Ag, Cd, In, Sn, Sb, Tl and Pb besides Zn, Fe and S is reported. Commercially available ZnS, FeS, CdS products were used as the major components, whereas the trace elements were added by doping with single-element ICP-MS standard solutions a…