An acylated flavonoid from Nierembergia hippomanica

A new acylflavonoid has been isolated from Nierembergia hippomanica and identified by chemical and spectral data as pinocembrin 7-O-β-(2?-O-acetyl)neohesperidoside.     

Biotransformation of o- and p-aminobenzoic acids and N-acetyl p-aminobenzoic acid by cell suspension cultures of Solanum mammosum

Some new biotransformation products, p-aminobenzoic acid 7-O-β-d-glucopyranosyl ester, N-acetyl p-aminobenzoic acid 7-O-β-d-glucopyranosyl ester, o-aminobenzoic acid 7-O-β-d-(β-1,6-O-d-glucopyranosyl)glucopyranosyl ester and o-aminobenzoic acid 7-O-β-d-glucopyranosyl ester were isolated from cell suspension cultures of Solanum mammosum following administration of p-aminobenzoic acid, N-acetyl p-aminobenzoic acid or o-aminobenzoic acid respectively. N-acetyl p-aminobenzoic acid and N-formyl p-aminobenzoic acid were also identified as cell suspension metabolites of p-aminobenzoic acid.     

Characterization and quantification of flavonoid glycosides in the Prunus genus by UPLC-DAD-QTOF/MS

Widely distributed in plants, flavonoids reduce the incidence of cancer and cardiovascular disease. In this study, flavonoid content and composition in members of the Prunus genus were evaluated using liquid chromatography with diode array and electrospray ionization mass spectrometric detection (UPLC-DAD-ESI/QTOF-MS). Flavonoids in plants of the Prunus genus include the basic structures of kaempferol, quercetin, and catechin, and exist as mono-, di-, or tri-glycoside compounds mono-acylated with acetic acid. A total of 23 individual flavonoids were isolated and confirmed, three of which appear to be newly identified compounds: quercetin 3-O-(2″-O-acetyl)neohesperidoside, quercetin 3-O-(4″-O-acetyl)rutinoside, and kaempferol 3-O-(4″-O-acetyl)rutinoside. Japanese apricot and Chinese plum contained the highest amounts of flavonoids in the Prunus genus. During the ripening stage of Japanese apricot, the total flavonol content was reduced, while the catechin content was increased.     

Flavones and flavone glycosides from Halophila johnsonii

Halophila johnsonii Eiseman is a shallow-water marine angiosperm which contains UV-absorbing metabolites. Studies on methanol extracts of H. johnsonii by means of HPLC-UV, NMR, HPLC-MS resulted in isolation and identification of seven previously unknown flavone glycosides: 5,6,7,3′,4′,5′-hexahydroxyflavone-7-O-β-glucopyranoside (1), 5,6,7,3′,4′,5′-hexahydroxyflavone-7-O-(6″-O-acetyl)-β-glucopyranoside (2), 6-hydroxyluteolin-7-O-(6″-O-acetyl)-β-glucopyranoside (3), 6-hydroxyapigenin-7-O-(6″-O-acetyl)-β-glucopyranoside (4), 6-hydroxyapigenin-7-O-(6″-O-[E]-coumaroyl)-β-glucopyranoside (5), 6-hydroxyapigenin-7-O-(6″-O-[E]-caffeoyl)-β-glucopyranoside (6) and 6-hydroxyluteolin-7-O-(6″-O-[E]-coumaroyl)-β-glucopyranoside (7). Also isolated were three known flavone glycosides, 6-hydroxyluteolin 7-O-β-glucopyranoside (8), scutellarein-7-O-β-glucopyranoside (9), and spicoside (10), and five known flavones, pedalitin (11), ladanetin (12), luteolin (13), apegenin (14) and myricetin (15). Qualitative comparison of the flavonoid distribution in the leaf and rhizome-root portions of the plant was also investigated, with the aim of establishing the UV-protecting roles that flavonoids played in the sea grass.     

C31,-secodammarane-type triterpenoid saponins from the male flowers of Alnus pendula

Six C₃₁-secodammarane-type triterpenoid saponins, in addition to alnustic acid, were isolated from the male flowers of Alnus pendula. Two of these saponins were new and were shown to be the 12-O-(2′-O-acetyl)-β-d-xylopyranoside and the 12-O-(2′-O-acetyl)-β-d-glucopyranoside of alnustic acid, respectively, on the basis of their physico-chemical data.     

Acylated flavonol tetraglycosides from Delphinium gracile

An ethanol extract of the aerial parts of Delphinium gracile DC. yielded five flavonol glycosides quercetin-3-O-{[β-d-xylopyranosyl (1 → 3)-4-O-(E-p-caffeoyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranosyl (1 → 2)]}-β-d-glucopyranoside (1), quercetin-3-O-{[β-d-xylopyranosyl (1 → 3)-4-O-(E-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranosyl (1 → 2)]}-β-d-glucopyranoside (2), quercetin-3-O-{[β-d-xylopyranosyl (1 → 3)-4-O-(Z-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranosyl (1 → 2)]}-β-d-glucopyranoside (3), kaempferol-3-O-{[β-d-glucopyranosyl (1 → 3)-4-O-(E-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranoside-7-O-(4-O-acetyl)-α-l-rhamnopyranoside (4) kaempferol-3-O-{[β-d-glucopyranosyl (1 → 3)-4-O-(E-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranoside-7-O-(4-O-acetyl)-α-l-rhamnopyranoside (5) in addition to 4-(β-d-glucopyranosyloxy)-6-methyl-2H-pyran-2-one (6) and rutin. Structures were elucidated by spectroscopic methods.     

Astrasieversianins IX,XI and XV,cycloartane derived saponins from Astragalus sieversianus

Sixteen triterpenoid saponins, astrasieversianins I–XVI, have been isolated from the methanol extract of the roots of Astragalus sieversianus. By heterogeneous acidic hydrolysis, all glycosides produced only one common aglycone which was identified as the known natural product astramembrangenin or cycloastragenol. On the basis of spectral analysis and chemical reactions, the structures of two new triterpenoid glycosides, astrasieversianin IX and XI, were assigned as the 3-0-[α-l-rhamnopyranosyl(1 → 2)]-(3'-O-acetyl)-β-d-xylopyranosyl-6-O-β-d-xylopyranoside and the 3-O-[α-l-rhamnopyranosyl(1 → 2)]-(4'-O-acetyl)-β-d-xylopyranosyl-6-β-d-xylopyranoside of cycloastragenol. Astrasieversianin XV was identified as the 20,24-epimer (20R,24S) of cyclosieversiside G (20S,24R).     

Acylated flavonol glucosides of Pinus contorta needles

From fresh Pinus contorta Doug (Coastal) needles four flavonol acylated glucosides and 6-methyl-kaempferol 3-β-D-glucoside were isolated. The three monoacylated glucosides were kaempferol-3-β-D(6-O-p- coumaryl)glucoside, isorhamnetin-3-β-D-(6-O-acetyl)glucoside, quercetin-3-β-D-(p-coumaryl)glucoside and the diacyl compound was kaempferol-3-β-D-(di-p-coumaryl)glucoside.     

Identification of 2-O (indole-3-acetyl)-D-glucopyranose, 4-O-(indole-3-acetyl)-D-glucopyranose and 6-O-(indole-3-acetyl)-D-glucopyranose from kernels of Zea mays by gas-liquid chromatography-mass spectrometry

New esters of indole-3-acetic acid and d-glucose have been isolated from mature sweet-corn kernels of Zea mays. The esters were resolved by t.l.c. into two fractions having R_F values distinct from that of authentic 1-O-(indole-3-acetyl)-β-d-glucopyranose. Analysis of the trimethylsilyl ethers of the two fractions by combined gas-liquid chromatography-mass spectrometry (g.l.c.-m.s.) showed that the esters have a free carbonyl group. Labeling of the carbonyl carbon atom with an O-methyloxime group, and analysis of the O-trimethylsilyl O-methyloxime derivatives by g.l.c.-m.s. permitted the new compounds to be identified as a mixture of 2-O-(indole-3-acetyl)-d-glucopyranose, 4-O-(indole-3-acetyl)-d-glucopyranose, and 6-O-(indole-3-acetyl)-d-glucopyranose.     

Identification of N, O-diacetyl-, N-acetyl- and N-glycolylneuraminyl-(2 → 3)-lactose in rat urine

The structure of three neuraminyl-oligosaccharides isolated from rat urine-have been studied by chromatographic and mass spectrometric analyses of different hydrolysis and methylation products. The structures of the oligosaccharides were identifies as O-α-N-acetyl(O-acetyl)neuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose, O-α-N-acetylneuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose and O-α-N-glycolylneuraminyl-(2 → 3)-O-β-galactopyranosyl-(1 → 4)-glucopyranose.     

Anthocyanins from red flowers of Camellia cultivar 'Dalicha'

Five anthocyanins, cyanidin 3-O-(2-O-β-xylopyranosyl-6-O-(Z)-p-coumaroyl)-β-galactopyranoside (2), cyanidin 3-O-(2-O-β-xylopyranosyl-6-O-(E)-p-coumaroyl)-β-galactopyranoside (3), cyanidin 3-O-(2-O-β-xylopyranosyl-6-O-(E)-caffeoyl)-β-galactopyranoside (4), cyanidin 3-O-(2-O-β-xylopyranosyl-6-O-acetyl)-β-galactopyranoside (5), and cyanidin 3-O-(2-O-β-xylopyranosyl-6-O-acetyl)-β-glucopyranoside (6), together with the known cyanidin 3-O-(2-O-β-xylopyranosyl)-β-galactopyranoside (1), were isolated from red flowers of Camellia cultivar ‘Dalicha’ (Camellia reticulata) by chromatography using open columns. Their structures were subsequently determined on the basis of spectroscopic analyses, i.e., ¹H NMR, ¹³C NMR, HMQC, HMBC, HR ESI-MS and UV-vis.     

Hydrogenolysis of benzylidene acetals of 1,6-anhydro-β-d-galactopyranose derivatives with the LiAlH4—AlCl3 reagent

Benzylidenation of 1,6-anhydro-β-d-galactopyranose (1) and its 2-O-acetyl (2) and 2-O-allyl (3) derivatives under various conditions afforded mixtures of 1,6-anhydro-exo- and -endo-3,4-O-benzylidene-β-d-galactopyranose (4 and 5) and the2-O-acetyl (6 and 7) and 2-O-allyl (8 and 9) derivatives, respectively. Hydrogenolysis of the exo (4 and 8) or the endo (5 and 9) derivatives with the LiAlH₂—AlCl₃ reagent gave only the 3-O-benzyl derivatives (10 and 11).     

The synthesis of oligosaccharide-asparagine compounds. V. O- -D-mannopyranosyl-(1 leads to 6)-O-(2-acetamido-2-deoxy- -D-glucopyranosyl)-(1 leads to 4)-2-acetamido-N-(L-aspart-4-oyl)-2-deoxy- -D-glucopyranosylamine

O-α-d-Mannopyranosyl-(1→6)-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-(1→4)-2-acetamido-N-(l-aspart-4-oyl)-2-deoxy-β-d-glucopyranosylamine (12), used in the synthesis of glycopeptides and as a reference compound in the structure elucidation of glycoproteins, was synthesized via condensation of 2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl bromide with 2-acetamido-4-O-(2-acetamido-3-O-acetyl-2-deoxy-β-d-glucopyranosyl)-3,6-di-O-acetyl-2-deoxy-β-d-glucopyranosyl azide (5) to give the intermediate, trisaccharide azide 7. [Compound 5 was obtained from the known 2-acetamido-4-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)-3,6-di-O-acetyl-2-deoxy-β-d-glucopyranosyl azide by de-O-acetylation, condensation with benzaldehyde, acetylation, and removal of the benzylidene group.] The trisaccharide azide 6 was then acetylated, and the acetate reduced in the presence of Adams' catalyst. The resulting amine was condensed with 1-benzyl N-(benzyloxycarbonyl)-l-aspartate, and the O-acetyl, N-(benzyloxycarbonyl), and benzyl protective groups were removed, to give the title compound.     

Enzymatic Esterification of Indole-3-acetic Acid to myo-Inositol and Glucose

Incubation of mature sweet corn kernels of Zea mays in dilute solutions of ¹⁴C-labeled indole-3-acetic acid leads to the formation of ¹⁴C-labeled esters of myo-inositol, glucose, and glucans. Utilizing this knowledge it was found that an enzyme preparation from immature sweet corn kernels of Zea mays catalyzed the CoA- and ATP-dependent esterification of indole-3-acetic acid to myo-inositol and glucose. The esters formed were 2-O-(indole-3-acetyl)-myo-inositol, 1-dl-1-O-(indole-3-acetyl)-myo-inositol, di-O-(indole-3-acetyl)-myo-inositol, tri-O-(indole-3-acetyl)-myo-inositol, 2-O-(indole-3-acetyl)-d-glucopyranose, 4-O-(indole-3-acetyl)-d-glucopyranose and 6-O-(indole-3-acetyl)-d-glycopyranose. An assay system was developed for measuring esterification of ¹⁴C-labeled indole-3-acetic acid by ammonolysis of the esters followed by isolation and counting the radioactive indole-3-acetamide.     

Ketodeoxyhexosylpurines. Synthesis and properties of keto derivatives of 7-(beta-L-fucopyranosyl)-theophylline

Catalytic fusion of 1,2,3,4-tetra-O-acetyl-L-fucose with theophylline gave 7-(2,3,4-tri-O-acetyl-6-deoxy-β-L-galactopyranosyl)theophylline (1) which was deacetylated with sodium methoxide to give 7-(6-deoxy-β-L-galactopyranosyl)theophylline (2), further transformed by selective condensation with acetone into 7-(6-deoxy-3,4-O-isopropylidene-β-L-galactopyranosyl)theophylline (3). Oxidation of 3 employing a modified Pfitzner-Moffatt procedure led to 7-(6-deoxy-3,4-O-isopropylidene-β-L-lyxo-hexopyranosulosyl)theophylline (5). However, treatment of 3 with dimethyl sulfoxide-acetic anhydride according to the procedure used for deoxy hexoses gave only the 2′-O-acetyl analog 4. Treatment of 5 with alkali showed it to be more stable than 2′-ketouridine or 2′-ketocytidine. Finally, in vivo biological assays showed that 7-(6-deoxy-β-L-lyxo-hexopyranosulosyl)theophylline (7) inhibits cellular growth, whereas the nucleoside 2 is inactive before oxidation.     

Chemotaxonomic contribution to the Sideritis species dilemma on the Balkans

Forty-two samples of Sideritis species (Sideritis scardica, Sideritis raeseri, Sideritis syriaca, Sideritis taurica and Sideritis lanata) from the Balkan Peninsula were evaluated for their polyphenolic profiles in order to establish a correlation between the taxonomy, geographical location and nature and content of phenolic compounds.Eight compounds were detected in all analyzed Sideritis samples: 5-caffeoylquinic acid, lavandulifolioside, verbascoside, isoscutellarein 7-O-allosyl(1→2)glucoside, hypolaetin 7-O-[6‴-O-acetyl]-allosyl(1→2)glucoside, isoscutellarein 7-O-[6‴-O-acetyl]-allosyl(1→2)glucoside, 3′-O-methylhypolaetin 7-O-[6‴-O-acetyl]-allosyl(1→2)glucoside and 4′-O-methylhypolaetin 7-O-[6‴-O-acetyl]-allosyl-(1→2)-[6″-O-acetyl]-glucoside). They present from 50 to 80% of total phenolic content in S. scardica, S. raeseri, S. syriaca and S. taurica and up to 90% in S. lanata and the similarity of their polyphenolic profiles implies that they are systematically very closely related.Based on their polyphenolic patterns, very good differentiation between the samples of S. lanata (sect. Hesiodia) and S. scardica, S. syriaca and S. raeseri (sect. Empedoclia) was observed, that is mainly due to the very high content of 5-cafeoylquinic acid and very low amount of phenylethanoid glycosides and flavonoid glycosides.The obtained results demonstrate considerable degree of similarity between S. scardica, S. raeseri and Bulgarian S. syriaca that give contribution to the dilemma that Bulgarian S. syriaca is very similar to Turkish S. taurica and suggest further verification of its taxonomic status.     

Acetylated allose-containing flavonoid glucosides from Stachys anisochila

In continuation of our chemosystematic study of Stachys (Labiatae) we have isolated the previously reported isoscutellarein 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-β-D-glucopyranoside] (1) and 3′-hydroxy-4′-O-methylisoscutellarein 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-β-D-glucopyranoside] (4) and four new allose-containing flavonoid glycosides from S. anisochila. The new glycosides are hypolaetin 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-β-D-glucopyranside] (6) as well as the three corresponding diacetyl analogues of 1, 4 and 6, isoscutellarein 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-6″-O-acetyl-β-D-glucopyranoside], 3′-hydroxy-4′-O-methylisoscutellarein 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-6″-O-acetyl-β-D-glucopyranoside] and hypolaetin 7-O-[6″'-O-acetyl-β-D-allopyranosyl-(1 → 2)-6″-O-acetyl-β-D-glucopyranoside]. Extensive two-dimensional NMR studies (proton-carbon correlations, COSY experiments) allowed assignment of all ¹H NMR sugar signals and a correction of the ¹³C NMR signal assignments for C-2 and C-3 of the allose.     

Phenolic Glycosides with antiproteasomal activity from Centaurea urvillei DC. subsp. urvillei

A new flavanone glycoside, naringenin-7-O-β-d-glucuronopyranoside, and a new flavonol glycoside, 6-hydroxykaempferol-7-O-β-d-glucuronopyranoside were isolated together with 12 known compounds, 5 flavone glycoside; hispidulin-7-O-β-d-glucuronopyranoside, apigenin-7-O-β-d-methylglucuronopyranoside, hispidulin-7-O-β-d-methylglucuronopyranoside, hispidulin-7-O-β-d-glucopyranoside, apigenin-7-O-β-d-glucopyranoside, a flavonol; kaempferol, two flavone; apigenin, and luteolin, a flavanone glycoside; eriodictyol-7-O-β-d-glucuronopyranoside, and three phenol glycoside; arbutin, salidroside, and 3,5-dihydroxyphenethyl alcohol-3-O-β-d-glucopyranoside from Centaurea urvillei subsp. urvillei. The structure elucidation of the new compounds was achieved by a combination of one- (¹H and ¹³C) and two-dimensional NMR techniques (G-COSY, G-HMQC, and G-HMBC) and LC-ESI-MS. The isolated compounds were tested for their antiproteasomal activity. The results indicated that kaempferol, a well known and widely distributed flavonoid in the plant kingdom, was the most active antiproteasomal agent, followed by apigenin, eriodictyol-7-O-β-d-glucuronopyranoside, 3,5-dihydroxyphenethyl alcohol-3-O-β-d-glucopyranoside, and salidroside, respectively.     

Flavonoid glycosides from needles of Pinus massoniana

Seven flavonoids have been isolated from Pinus massoniana needles and identified as taxifolin and its 3′-O-β-D-glucopyranoside, (+)-catechin, naringenin-7-O-β-D-glucopyranoside and three new flavonoid glycosides, 6-C-methylaromadendrin 7-O-β-D-glucopyranoside, taxifolin 3′-O-β-D-(6″-O-phenylacetyl)-glucopyranoside and eriodictyol 3′-O-β-D-glucopyranoside.