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The potential of one- and two-dimensional NMR techniques for the identification of individual sugar residues, their anomeric configuration, interglycosidic linkages, sequencing and the site of any appended group, in establishing the structures of naturally occurring oligosaccharides and glycosides is presented.
From an ethanolic extract of the influorescence of Yucca aloifolia a new spirostanol glycoside has been isolated and characterized as 3-O[(alpha-L-rhamnopyranosyl(1----3)-beta-D-xylopyranosyl(1----2))(beta- D-glucopyranosyl(1----3)-beta-D-glucopyranosyl(1----3)-beta-D-glucopy ranosyl]-25R,5 alpha-spirostan-2 alpha, 3 beta-diol.
Seven flavonol glycosides were isolated from a leaf extract of cabbage and characterized by chemical and spectroscopic methods including 1H and 13C NMR and negative ion FAB-MS. Five compounds were new natural products or were fully characterized for the first time. They are derivatives of kaempferol-3-O-beta-D-sophoroside-7-O-beta-D-glucoside acylated at C-2"' with either caffeic acid, p-coumaric acid or ferulic acid, and of quercetin-3-O-beta-D-sophoroside-7-O-beta-D-glucoside acylated with either caffeic acid or ferulic acid. Kaempferol-3-O-beta-D- sophoroside-7-O-beta-D-glucoside and kaempferol-3-O-beta-D-(2-sinapoylsophoroside)-7-O-beta-D-glucoside were found for the first time in cabbage, but they have previously been found in other Brassica species.
Three new phenylethanoid glycosides, 2-(4-hydroxyphenyl)ethyl-beta-D-apiosyl-(1----6)-beta-D-glucopy ranoside(osmanthuside H), 2-(4-hydroxyphenyl)ethyl 5-O-trans-p-coumaroyl-beta-D-apiosyl(1----6)-beta-D-gluc+ ++ opy ranoside (osmanthuside I) and 2-(4-hydroxyphenyl)ethyl 5-O-trans-feruloyl-beta-D-apiosyl-(1----6)-beta-D-glucopy r ano side (osmanthuside J), were isolated from the bark of Osmanthus asiaticus. The structures were elucidated on the basis of spectroscopic evidence.
From a water extract of whole plants of Sesamum indicum, two new, and six known phenylethanoid glycosides, and three new triglycosides which had the same sugar sequence were isolated. The structures of the new compounds were elucidated from chemical and spectroscopic evidence.
Chemical studies of the bulbs of Allium albopilosum and A. ostrowskianum have led to the isolation of two new steroidal saponins and four new cholestane glycosides together with several known compounds. The structures of the new compounds were established by the spectroscopic data, hydrolysis and chemical correlations as (25 R and S)-5 alpha-spirostane-2 alpha,3 beta,6 beta-triol 3-O-(O-beta-D-glucopyranosyl-(1-->2)-O-[3-O-acetyl-beta-D-xylopyranosyl- (1-->3)]-O-beta-D-glucopyranosyl-(1-->4)-beta-D-galactopyranoside), (25R)-2-O-[(S)-3-hydroxy-3-methylglutaroyl]-5 alpha-spirostane-2 alpha, 3 beta, 6 beta-triol 3-O-(O-beta-D-glucopyranosyl-(1-->2)-O-[beta-D-xylopyranosyl-(1-->3)]-O- beta-D-glucopyranosyl-(1-->4)-beta-D-galactopyranoside), (22S)-cholest-5-ene-1 beta,3 beta,16 beta,22-tetraol 1-O-alpha-L-rhamnopyranoside 16-O-(O-alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucopyranoside), 1 beta,3 beta,16 beta-trihydroxycholest-5-en-22-one 1-O-alpha-L-rhamnopyranoside 16-O-(O-alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucopyranoside), 1 beta,3 beta,16 beta-trihydroxy-5 alpha-cholestan-22-one 1-O-alpha-L-rhamnopyranoside 16-O-(O-alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucopyranoside) and (22S)-cholest-5-ene-1 beta,3 beta,16 beta,22-tetraol 16-O-(O-beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranoside).
Investigation of the inner bark of Alyxia reinwardti var. lucida led to the isolation of two new coumarin glycosides, 1 and 2, whose structures were determined by interpretation of their spectroscopic data, particularly NMR spectroscopy.
Five new triterpenoid glycosides designated decaisosides A-E together with five known ones were isolated from the stems of Decaisnea fargesii. Their structures were established by means of chemical and spectroscopic evidence.
Two new flavone diglycosides along with 7,4'-O-dimethylscuttelarein 6-O-beta-D-glucopyranoside, a known glycoside, were isolated from the seeds of Gelonium multiflorum and their structures were elucidated as 7,4'-O-dimethylscuttelarein 6-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranoside and 6-O-beta-D-xylopyranosyl(1-->2)-beta-D-glucopyranoside.
A new phenylethanoid glycoside, plantasioside, was isolated from the aerial parts of Plantago asiatica. The structure of plantasioside was deduced from chemical and spectral evidence to be 1',2'-[beta(3,4-dihydroxyphenyl)-alpha,beta-dioxoethanol]-6'-O- caffeoyl- O-beta-D-glucopyranoside. In addition, the structure of orobanchoside from P. depressa and P. camtschatica was revised to be 1',2'-[beta(3,4-dihydroxyphenyl)- alpha,beta-dioxoethanol]-4'-O-caffeoyl-O-alpha-L-rham- nopyranosyl-(1-->3)-O- beta-D-glucopyranoside from beta-hydroxy-[beta(3,4-dihydroxyphenyl)-ethyl]-4'-O-caffeoyl-O-alp ha-L- rhamnopyranosyl-(1-->2)-O-beta-D-glucopyranoside.
A bioactivity guided fractionation, using KB cells and brine shrimp assays, of the methanolic extract from the leaves of Picramnia antidesma yielded two known anthraquinones, aloe-emodin and aloe-emodin anthrone, and three new aloe-emodin C-glycosides, named picramnioside A, picramnioside B and picramnioside C. Structures were established by spectroscopic methods (UV, IR, mass spectrometry, 1H and 13C and 2D NMR including COSY 45, HMQC, HMBC and ROESY). CD was used to establish the absolute configuration of the picramniosides.
A new oleanane-type triterpene saponin named asteryunnanoside E and a new acetylene glycoside named asteryunnanoside I have been isolated from the roots of Aster yunnanensis, and their structures elucidated as 3-O-beta-D-glucopyranosyl-bayogenin-28-O-beta-D- glucopyranosyl-(1-->2)-beta-D-glucopyranoside and 2Z,8E-decadiene-4,6-diyn-1-O-beta-D-glucopyranos yl-(1-->2)-beta-D- glucopyranoside by means of 1D and 2D NMR techniques (COSY, HETCOR, COLOC, HOHAHA and ROESY) and chemical transformations.
Eleven new pregnane ester glycosides have been isolated from the aerial parts of Stapelia variegata. Eight of the recognized compounds were established to possess the same trioside moiety, viz. 3-O-[3-O-methyl-6-deoxy-beta-D-allopyranosyl-(1-4)-beta-D- cymaropyranosyl-(1-4)-beta-D-cymaropyranoside]. These compounds were identified as: stavaroside A: 12-O-beta-angeloyl-20-O-benzoyl sarcostin; stavaroside B: 12-O-beta-angeloyl-20-O-tigloyl sarcostin; stavaroside C: 11 alpha-acetoxy 2 beta-benzoxy-3 beta,8 beta, 14 beta-trihydroxy-pregn-5-ene-20-one; stavaroside D: 11 alpha-acetoxy- 12 beta-tigloxy-3 beta,8 beta,14 beta-trihydroxy-pregn-5-ene-20-one; stavaroside E: 12-O-beta-benzoyl sarcostin; stavaroside F: 11 alpha-acetoxy-12 beta-acetoxy-3 beta,8 beta,14 beta-trihydroxy-pregn-5- ene-20-one; stavaroside G: 12-O-beta,20-O-diacetyl sarcostin and stavaroside H: 3 beta, 8 beta, 11 alpha, 12 beta, 14 beta-pentahydroxy-pregn-5- ene-20-one. The other three compounds were shown to possess the same tetraside sugar moiety, viz. 3-O-[beta-D-glucopyranosyl- (1-4)-3-O-methyl-6-deoxy-beta-D-allopyranosyl-(1-4)-beta-D-cymaropyra nosyl- (1-4)-beta-D-cymaropyranoside]. These compounds were identified as: stavaroside I: 1 alpha, 12 beta-angeloxy and benzoxy-3 beta,8 beta,14 beta-trihydroxy- pregn-5-ene-20-one; stavaroside J: 11 alpha-acetoxy-12 beta-benzoxy-3 beta, 8 beta,14 beta-trihydroxy-pregn-5-ene-20-one and stavaroside K: 11 alpha-acetoxy-12 beta-tigloxy-3 beta,8 beta,14 beta-trihydroxy-pregn-5-ene- 20-one. The structural elucidation of the isolated compounds was aided significantly on the basis of the chemical and spectral evidence. The decisive assignments of the ester positions were based on the Inverse Detected-Heteronuclear Multiple Bond Connectivity (HMBC) experiments.
The aerial part of Cynanchum caudatum afforded 10 new pregnane glycosides which had sarcostin or deacylmetaplexigenin as the aglycone moiety. The structures of these compounds were elucidated by spectroscopic methods and from chemical evidence.
Five cucurbitacin glycosides named cabenosides D-L were isolated from 'Cabeça-de-negro', the roots of Caput nigri. Among them, the structures of cabenosides D-H were elucidated as 10 alpha-cucurbit-5-en-11-oxo-3 beta,24R,25-triol-3-O-beta-D-glucopyranoside, 10 alpha-cucurbit-5-en-24-oxo-3 beta, 11 alpha,25-triol-25-O-beta-D- glucopyranosyl, [3,O-beta-D-glucopyranoside, 3-O-beta-D-glucopyranosyl-(1-2)-beta-D-glucopyranoside, 3-O-beta-D-glucopyranosyl-(1-6)-beta-D-glucopyranoside] and 10 alpha-cucurbit-5-en-11,24-dioxo-3 beta,25-diol-25-O-beta-D- glucopyranosyl, 3-O-beta-D-glucopyranosyl-(1-6)-beta-D-glucopyranoside, respectively, on the basis of chemical and spectral evidence.
The chemical structures of cabenosides I-L were investigated. These are four of the 12 cucurbitacin glycosides isolated from 'Cabeça-de-negro', the roots of Caput nigri. By means of chemical analyses the structures of cabenosides I-L were elucidated as 10 alpha-cucurbit-5-ene-3 beta,11 alpha,20S,24 xi,25-pentaol [3, 25-di-O-beta-D-glucopyranoside, and 3-O-beta-D-glucopyranosyl-(1-2)-beta-D-glucopyranosyl (sophorosyl), 25-O-beta-D-glucopyranoside], and 10 alpha-cucurbit-5,20,24-triene-11-oxo-3 beta,26-diol [3-O-beta-D-glucopyranosyl-(1-6)-beta-D-glucopyranosyl (gentiobiosyl), 26-O-beta-D-glucopyranoside and 3,26-di-O-gentiobioside], respectively.
Besides rutin, quercetin 3-rhamnoside and kaempferol 3-rhamnosyl(1-->6) galactoside, a new flavonol glycoside, quercetin 3-glucosyl(1-->4)galactoside, and 1,6,8-trihydroxy-3-methyl anthraquinone (emodin) have been characterized from leaves of Rumex chalepensis. The structures were established on the basis of Rf values, acid hydrolysis to aglycone and sugar and UV, EI and FAB-mass spectra, 1H NMR, 13C DEPT NMR, NOE difference measurement, 1H-H COSY and 1H-13C COSY spectral data.
Two new triterpenoid glycosides, quinovic acid-3 beta-O-beta-D- glucopyranosyl-(1-->4)-alpha-L-rhamnopyranoside and quinovic acid-3 beta-O-beta-D-glucopyranosyl-(1-->3)-beta-D-fucopyranoside (named rubelloside A and B, respectively), were isolated from roots of Adina rubella. Their structures were elucidated by spectral and chemical means. Rubelloside B exhibited immunological enhancement.