Search results for " Fast Atom Bombardment"
showing 10 items of 10 documents
Effects of glycosylation on fragments of tumour associated human epithelial mucin MUC1.
1998
The glycodecapeptide AcPAPGS(alpha GalNAc)T(alpha GalNAc)APPA and the C-terminal glycohexapeptide AcS(alpha GalNAc)T(alpha GalNAc)APPA have been synthesized by applying the N-terminal Fmoc group in combination with the heptyl ester cleavable by lipase-catalyzed hydrolysis at pH 7. The solution conformation of these MUC1-related synthetic glycopeptides and the control, non-glycosylated decapeptide AcPAPGSTAPPA have been investigated using NMR spectroscopy. The structural studies indicate that the glycohexapeptide has a folded structure in solution. For this molecule, unrestrained molecular dynamics has been used to confirm the presence of the observed solution through-space connections. The …
Novel bioactive bromopyrrole alkaloids from the Mediterranean sponge Axinella verrucosa
2005
The Mediterranean sponge Axinella verrucosa has been investigated for its alkaloid composition and has been found to produce a complex mixture of bromopyrrole alkaloids. Along with the previously isolated compounds 5-18, four novel alkaloids of this class, compounds 1-4, have been isolated, and their structures established through spectroscopic methods. Compounds 1-4 were found to display neuroprotective activity against the agonists serotonin and glutamate in vitro.
Two new biologically active triterpene saponins from Acanthophyllum squarrosum.
2000
Two novel triterpenoid saponins (1 and 2) have been isolated from the roots of Acanthophyllum squarrosum. The structures were established mainly by a combination of 2D NMR techniques as 3-O-beta-D-galactopyranosyl-(1-->2)-[beta-D-xylopyranosyl-(1-->3)]-be ta-D-glucuronopyranosylgypsogenin-28-O-beta-D-xylopyranosyl-(1-->3 )-b eta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->4)-[alpha-L- rhamnopyranosyl-(1-->3)]-beta-D-fucopyranoside (1) and 3-O-beta-D-glucopyranosylgypsogenin-28-O-alpha-L-rhamnopyranosyl-( 1-- >2)-alpha-L-arabinopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->6 )]- beta-D-glucopyranoside (2). Compound 1 showed a moderate concentration-dependent immunomodulatory effect …
A new biologically active acylated triterpene saponin from Silene fortunei.
1998
A new acylated triterpene-saponin (1), together with a mixture of the known jenisseensosides C and D, has been isolated from the roots of Silene fortunei. The structure of the new compound was established by chemical means and spectroscopic methods as 3-O-[beta-D-galactopyranosyl-(1-->2)-beta-D-glucuronopyranosyl]-28 -O- [[alpha-L-arabinopyranosyl-(1-->2)-alpha-L-arabinopyranosyl- (1-->3)-b eta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)]-[beta-D- glucopyranosyl-(1-->3)]-4-O-acetyl-beta-D-fucopyranosyl]quillaic acid. This saponin showed a significant enhancement of granulocyte phagocytosis in vitro.
Guest-to-host proton transfer in melatonin-beta-cyclodextrin inclusion complex by ionspray, fast atom bombardment and tandem mass spectrometry.
2001
Ionspray (IS) and fast atom bombardment (FAB) positive ionization mass spectrometry (MS) of 1:1 β-cyclodextrin (β-CD)-melatonin (MLT) host-guest complex allowed the detection of gaseous protonated 1:1 β-CD-MLT. Tandem MS collision-induced dissociation (CID) of such protonated 1:1 β-CD-MLT species showed the proton (charge) to be retained to a significant extent by the host and by its cage fragmentation products, in spite of the higher proton affinity of MLT with respect to that of β-CD. This requires an endothermic guest-to-host proton transfer to occur within the gaseous association. Collisional activation could be accounted for by the promotion of such an endothermic process; however…
Triterpene Saponins from Tupidanthus calyptratus
2001
Five new bisdesmosidic saponins (1--5) were isolated from the aerial parts of Tupidanthus calyptratus. Their structures were determined by (1)H--(1)H correlation spectroscopy (COSY, TOCSY, ROESY) and (1)H--(13)C correlation (HSQC, HMBC) NMR experiments, FABMS, and chemical data.
Biologically Active Triterpene Saponins from Callus Tissue of Polygala amarella
1999
A new bioactive saponin (1), together with a known saponin (polygalasaponin XXVIII) has been isolated from the callus tissue culture of Polygala amarella. Based on spectroscopic data, especially direct and long-range heteronuclear 2D NMR analysis and on chemical transformations, the structure of 1 was elucidated as 3-O-beta-D-glucopyranosyl presenegenin-28-O-beta-D-galactopyranosyl-(1 --> 3)-beta-D-xylopyranosyl-(1 --> 4)-alpha-L-rhamnopyranosyl-(1 --> 2)-[beta-D-glucopyranosyl-(1 --> 3)]-beta-D-fucopyranoside. Both saponins showed significant immunological properties based on the enhancement of granulocyte phagocytosis in vitro.
Sulfated Lupane Triterpene Derivatives and a Flavone C-Glycoside from Gypsophila repens
2007
A new sulfated lupane triterpene, Gypsophilin (1), and its glucosyl ester, Gypsophilinoside (2) were isolated from the roots of Gypsophila repens whereas a new flavone C-glycoside (3) was obtained from the aerial parts. Their structures were established as (3beta)-3-O-(sulfo)lup-20(29)-en-23,28-dioic acid (1), (3beta)-3-O-(sulfo)lup-20(29)-en-23,28-dioic acid -28-O-beta-D-glucopyranosyl ester (2) and luteolin-7-O-alpha-L-arabinopyranosyl-6-C-beta-glucopyranoside (3) by spectroscopic methods such as 1D and 2D NMR, HR-ESI-MS and FAB-MS.
Steroidal saponins from the roots of Smilax aspera subsp. mauritanica
2008
Two new steroidal saponins (1, 2) were isolated from the roots of Smilax aspera subsp. mauritanica (POIR.) ARCANG. (Liliaceae), together with the known curillin G (3), asparagoside E (4), asparoside A (5), asparoside B (6) and the phenolic compound resveratrol (7). Their structures were established mainly on the basis of 600 MHz 2D-NMR spectral data. 3 exhibited antifungal activity against the human pathogenic yeasts Candida albicans, C. glabrata and C. tropicalis (minimum inhibitory concentrations of 25, 25 and 50 microg/ml, respectively) whereas the other compounds were inactive.
Two New Glycosides from Astragalus caprinus
2001
A new glycoside of flavonol (1) and a new glycoside of a cycloartane-type triterpene (2) were isolated from the leaves and the roots of Astragalus caprinus, respectively. Their structures were elucidated in turn by spectroscopic data interpretation as 3-O-[[beta-D-xylopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->6)][beta-D-apiofuranosyl(1-->2)]]-beta-D-galactopyranosyl kaempferol (1) and 3-O-(beta-D-xylopyranosyl)-24-O-(beta-D-glucopyranosyl)-20,25-epoxycycloartane-3beta,6alpha,16beta,24alpha-tetrol (2).