Search results for "glycoside"
showing 10 items of 296 documents
Glycosidsynthese mit 2,3,4,6-Tetra-O-pivaloyl-α-D-glucopyrancsylbromid
1982
Die Glycosylierung von Benzylalkohol und Cholesterin gelingt mit 2,3,4,6-Tetra-O-pivaloyl-α-D-glucopyranosylbromid (2) in Gegenwart von Silbersalzen in hoher Ausbeute. Die bei Koenigs-Knorr-Synthesen mit 2,3,4,6-Tetra-O-acetyl-α-D-glucopyranosylbromid (5) storende Orthoesterbildung wird beim Einsatz von 2 weitgehend unterdruckt. Die Lenkung der Reaktion zugunsten der Glycosidbildung wird dadurch erklart, das der tert-Butyl-Substituent im zwischenzeitlich gebildeten Acyloxoniumion A den nucleophilen Angriff am Acyloxoniumkohlenstoff sterisch behindert. Glycoside Synthesis Using 2,3,4,6-Tetra-O-pivaloyl-α-D-glucopyranosyl Bromide In the presence of silver salts the glycosylation of benzyl alc…
Steviol Glycosides Stability after Pulsed Electric Technologies and Ultrasounds Treatments in Fruit Juice Blend Sweetened with Stevia rebaudiana
2016
Stevia rebaudiana bartoni due to its high content in steviol glycosides and the ability to serve as a natural antimicrobial to complement the effectiveness of pulsed electric technologies for food preservation, has been used more frequently to improve sensorial properties of liquid foods.
Flavones, sesquiterpene lactones and glycosides isolated from Centaurea aspera var. Stenophylla
1984
Abstract From the alcoholic extract of Centaurea aspera var. stenophylla benzoic acid, p-hydroxybenzoic acid, apigenin, 6-methoxyluteolin, 11,13-dehydromelitensin, melitensin, stenophyliolide, ethyl-7-O-apigenin-glucuronate and the glucosides of sitosterol and stigmasterol were isolated and characterized. Stenophyllolide was shown to be 9,15-dihydroxygermacra-1(10),4,11-trien-12,6-olide.
Phytochemical analysis of two Weigela florida cultivars, “Pink Poppet” and “Jean’s Gold”
2020
Abstract Nine different oleanane-type glycosides were extracted and isolated by various chromatographic methods from two Weigela florida cultivars, “Pink Poppet” and “Jean’s Gold”. From the roots of W. florida “Pink Poppet”, three monodesmosidic oleanolic acid saponins 1, 4, 5 were obtained, together with one hederagenin ester 6 from the leaves, and six bidesmosidic saponins 2, 3, 6-9 were isolated from the leaves of W. florida “Jean’s Gold”. Among compounds 1-9, three were previously undescribed (1-3) and six (4-9) were already published in the literature. Their structures were assigned by spectroscopic analysis mainly 2D NMR and mass spectrometry (ESI-MS). The cytotoxicity of the isolated…
Two New Acylated Tridesmosidic Saponins from Astragalus armatus
2010
Two new tridesmosidic glycosides of (3β,6α,16β,20R,24S)-20,24-epoxycycloartane-3,6,16,25-tetrol (=cycloastragenol), armatosides I and II (1 and 2, resp.), were isolated from the roots of Astragalus armatus (Fabaceae) as well as the known bidesmosidic glycosides of cycloastragenol, trigonoside II (3) and trojanoside H (4). Their structures were elucidated as (3β,6α,16β,20R,24S)-3-O-(2,3-di-O-acetyl-β-D-xylopyranosyl)-20,24-epoxy-25-O-β-D-glucopyranosyl-6-O-β-D-xylopyranosylcycloartane-3,6,16,25-tetrol (1), and (3β,6α,16β,20R,24S)-3-O-(2-O-acetyl-β-D-xylopyranosyl)-20,24-epoxy-25-O-β-D-glucopyranosyl-6-O-β-D-xylopyranosylcycloartane-3,6,16,25-tetrol (2). These structures were established by e…
Quantitative Comparison of Free and Bound Volatiles of Two Commercial Tomato Cultivars (Solanum lycopersicumL.) during Ripening
2009
The changes in the profile of both free and glycosidically bound volatiles were studied in Moneymaker and Raf tomato cultivars during fruit ripening. The concentrations of 20 of 24 and of 27 of 30 compounds detected in the free volatile fraction (FVF) and glycosidically bound fraction (GBF), respectively, differed significantly between cultivars during ripening. Most free and bound volatiles increased during ripening in both cultivars. The contribution of each free volatile compound to the overall aroma was estimated by calculating its log U value, which indicated that only 11 compounds seem to exert a strong influence. Nine volatiles were detected exclusively in the GBF, among them geranio…
Monoterpenes in grape juice and wines.
2000
The importance of monoterpenes on varietal flavour of wines has been reviewed. These compounds were mainly found linked to sugar moieties in the grape juice and wines, showing no olfactive characteristics. In this way, mechanisms to liberate terpenes were studied, making a comparative study between acidic and enzymic hydrolysis of terpene glycosides. Finally, analytical techniques developed to study these compounds, in both free or glycosidically forms, and also to fractionate glycosidic precursors, have been discussed.
Cycloartane Glycosides from Three Species of Astragalus (Fabaceae)
2011
Nine cycloartane-type glycosides were isolated from three species of the genus Astragalus (Fabaceae): From the aerial parts of A. cicer L., two new saponins, cicerosides A and B (1 and 2, resp.), i.e., a tetradesmosidic and tridesmosidic cycloartane-type glycosides besides one known compound, from the roots of A. sempervirensLam., one known saponin, and from the roots of A. ptilodesBoiss. var. cariensisBoiss., five known compounds. Their structures were established mainly by 600-MHz 2D-NMR techniques (1H,1H-COSY, TOCSY, NOESY, HSQC, and HMBC) and mass spectroscopy.
Three Spirostanol Glycosides from the Seeds of Hyoscyamus Niger L.
2006
Three steroidal glycosides of spirostane series have been isolated from the seeds of Hyoscyamus niger L.(Solanaceae). Their structures were determined on the basis of chemical evidence and extensive spectroscopic methods including one-dimensional, two-dimensional NMR and MS analysis. In the genus Hyoscyamus the given compounds have been found out for the first time.
Foetidissimosides C–F, Novel Glycosides from the Roots ofCucurbita foetidissima
2004
Two novel echinocystic acid (=(3β,16α)-3,16-dihydroxyolean-12-en-28-oic acid) glycosides, foetidissimosides C (1), and D (2), along with new cucurbitane glycosides, i.e., foetidissimosides E/F (3/4) as an 1 : 1 mixture of the (24R)/(24S) epimers, were obtained from the roots of Cucurbita foetidissima. Their structures were elucidated by means of a combination of homo- and heteronuclear 2D-NMR techniques (COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC), and by FAB-MS. The new compounds were characterized as (3β,16α)-28-{[O-β-D-glucopyranosyl-(13)-O-β-D-xylopyranosyl-(14)-O-6-deoxy-α-L-mannopyranosyl-(12)-α-L-arabinopyranosyl]oxy}-16-hydroxy-28-oxoolean -12-en-3-yl β-D-glucopyranosiduronic acid (1…