A new acylated flavonoid tetraglycoside with anti-inflammatory activity from Tipuana tipu leaves

A new acylated kaempferol glycoside, kaempferol 3-O-α-l-rhamnopyranosyl-(1 → 6)-O-[β-d-glucopyranosyl-(1 → 2)-4-O-acetyl-α-l-rhamnopyranosyl-(1 → 2)]-β-d-galactopyranoside, has been isolated from the leaves of Tipuana tipu (Benth.) Lillo growing in Egypt, along with three known flavonol glycosides, kaempferol 3-O-rutinoside, quercetin 3-O-rutinoside (rutin) and kaempferol 3-O-[α-l-rhamnopyranosyl-(1 → 6)]-[α-l-rhamnopyranosyl-(1 → 2]-β-d-glucopyranoside. Structure elucidation was achieved through different spectroscopic methods. Structure relationship with anti-inflammatory activity using carrageenin-induced rat paw oedema model is discussed.     

New flavonol glycosides from the leaves of Caragana brachyantha

Two new flavonol glycosides, brachysides C and D, together with three known flavonol glycosides, were isolated from the leaves of Caragana brachyantha. The structures of brachysides C and D were elucidated on the basis of detailed spectroscopic analysis as quercetin 5-O-[α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside]-7-O-[α-l-rhamnopyranoside] and quercetin 5-O-[α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside]-7-O-[α-l-rhamnopyranoside]-4′-O-[α-l-rhamnopyranoside], respectively. The presence of flavonol tetra- and triglycosides bearing a sugar moiety at position 5 was the first report from this genus Caragana.     

A new flavonol glycoside and other flavonoids from the aerial parts of Taverniera aegyptiaca

Isolation of flavonoids from the aerial parts of Taverniera aegyptiaca Bioss. (Fabaceae) led to identification of one new flavonol glycoside, isorhamnetin-3-O-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside (1), along with eleven compounds, which previously have not been isolated from this plant quercetin-3-O-α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→6)-β-d-galactopyranoside] (2), isorhamnetin-3-O-α-l-arabinopyranoside (3), quercetin-3-O-α-l-rhamnopyranosyl-(1→6)-β-d-glucopyranoside (4), isorhamnetin-3-O-α-l-rhamnopyranosyl-(1→6)-β-d-glucopyranoside (7), isorhamnetin 3-O-α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→6)-β-d-galactopyranoside] (8), isorhamnetin 3-O-α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→6)-β-d-glucopyranoside] (9), kaempferol 3-O-α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→6)-β-d-galactopyranoside] (10), isorhamnetin (11), 4,4′-dihydroxy-2′-methoxychalcone (12), formononetin (13) and calycosin (15)] and some compounds already known from this plant [quercetin-3-O-robinobioside (5), isorhamnetin-3-O-robinobioside (6), afrormosin (14) and odoratin (16)].     

A new steroidal glycoside from Corypha taliera Roxb., a globally endangered species

The reversed-phased HPLC analysis of the methanol extract of the pericarp of C. taliera Roxb. (Talipalm), a rare species of Arecaceae family, afforded a new steroidal glycoside, β-sitosterol-3-O-α-l-rhamnopyranosyl-(1→4)-β-d-xylopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-β-d-glucopyranoside (1). The structure of the compound was elucidated unequivocally by UV, IR, HR-ESI-MS, ¹H and ¹³C NMR spectroscopic studies.     

Flavonoids of Alcea rosea L. and their immune stimulant,antioxidant and cytotoxic activities on hepatocellular carcinoma HepG-2 cell line

Alcea rosea L. is widely cultivated in gardens of Egypt as an ornamental plant and it has a great history of folkloric medicinal uses. In the present work, phytochemical investigation of the alcoholic extract of the flowers of A. rosea L. led to the isolation of six flavonoids (1–6). Dihydrokaempferol-4′-O-β-d-glucopyranoside (1), dihydrokaempferol (2), kaempferol-3-O-[6″-(E-coumaroyl)]-β-d-glucopyranoside (3), kaempferol-3-O-β-d-glucopyranoside (4), Apigenin (5) and kaempferol-3-O-α-l-rhamnopyranosyl-(1′″→6″)-β-d-glucopyranoside (6). Four of the isolated compounds were evaluated for their antioxidant, immunostimulant and cytotoxic activities against HepG-2 cell line. Compound (3) showed potent cytotoxic activity against HepG-2 cell line with high selectivity towards hepatocellular carcinoma in vitro (with IC₅₀ = 3.8 μg/mL). Compounds 1 and 2 exhibited significant antioxidant activity and compound 4 showed a significant immune stimulant activity. Compound 1 is isolated for the first time from genus Alcea and this is the first report for its biological investigation.     

A new triterpenoid glycoside from the leaves and stems of Duranta repens

A new triterpenoid glycoside (1) was isolated from the methanol extract of the leaves and stems of Duranta repens L. (Verbenaceae) along with 14 known compounds consisting of eight triterpenoids, four iridoids, one phenylethanoid glycoside and one flavonoid. The chemical structure of 1 was determined to be bayogenin 3-O-[β-D-glucopyranoside]-28-O-[α-L-rhamnopyranosyl-(1→5)-O-β-D-apiofuranosyl-(1→4)-O-α-L-rhamnopyranosyl-(1→2)-O-α-L-arabinopyranosyl] ester, based on spectroscopic data. In addition, the inhibitory effects of the isolates on lipoxygenase activity were examined. Among them, acteoside and apigenin resulted in 94 ± 3.6% and 82 ± 4.7% inhibition, respectively, at 0.5 mM.     

NON-ANOMERIC SUGAR ISOUREAS

Six non-anomeric isourea derivatives of d-fructose (7, 8), d-glucose (9, 10), 6-deoxy-l-altrose (11) and l-rhamnose (12) were synthesized from the precursors 1–6 by a CuCl-catalyzed addition of a non-glycosidic OH-group to DCC and DIPC, respectively. Subsequently, the isoureido group of phenyl 2,3,4-tri-O-benzyl-6-O-(N,N′-dicyclohexylisoureido)-β-d-glucopyranoside (10) was replaced by an azido and a thioacetyl group, respectively, yielding the corresponding 6-deoxy-6-azido-d-glucopyranoside (13) and 6-deoxy-6-thioacetyl-d-glucopyranoside (14) in moderate to good yields.     

Two new triterpenoids from Nauclea officinalis

Two new triterpenoids and three 27-nor-triterpenoids were isolated from the stems (with bark) of Nauclea officinalis. Their structures were identified to be 2β,3β,19α,23-tetrahydroxy-urs-12-en-28-oic acid (1), 2β,3β,19α,23-tetrahydroxy-urs-12-en-28-O-[β-d-glucopyranosyl (1-2)-β-d-glucopyranosyl] ester (2), pyrocincholic acid 3β-O-α-l-rhamnopyranoside (3), pyrocincholic acid 3β-O-α-l-rhamnopyranosy1-28-O-β-d-glucopyranosyl ester (4), pyrocincholic acid 3β-O-α-l-rhamnopyranosy1-28-O-β-d-glucopyranosyl-(1-6)-β-d-glucopyranosyl ester (5) by spectroscopic methods including 1D, 2D NMR and HR-MS analyses. The cytotoxic activity of 1–5 against lung cancer A-549 cells was also investigated.     

A Convenient Synthesis of Pyranosyl-1-carbaldoximes

Abstract

A simple high-yielding procedure is described for the preparation of tri-O-acetyl-β-l-fucopyranosylformaldoxime (1) involving stannate(II)-mediated reduction of the readily accessible tri-O-acetyl-β-l-fucopyranosylnitromethane (3). The d-mannosyl, d-glucosyl, d-galactosyl, and d-xylosyl analogues 7–12 were prepared similarly. The structure of tetra-O-acetyl-β-d-mannopyranosylformaldoxime (7) was determined by X-ray crystallography.     

Mimics of the Structural Elements of Type III Group B Streptococcus Capsular Polysaccharide. Part I: Synthesis of a Carboxylate-Containing Pentasaccharide

Abstract

A carboxylate-containing pentasaccharide, methyl O-(β-d-galactopyranosyl)-(1→4)-O-(β-d-glucopyranosyl)-(1→6)-O-{3-O-[(S)-1-carboxyethyl]-β-d-galactopyranosyl-(1→4)-O}-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-(1→3)-β-d-galactopyranoside (27) was synthesized by block condensation of suitably protected donors and acceptors. Phenyl 3-O-benzyl-4,6-di-O-chloroacetyl-2-deoxy-2-phthalimido-1-thio-β-d-glucopyranoside (17) was condensed with methyl 2,4,6-tri-O-benzyl-β-d-galactopyranoside (4) to afford a disaccharide, methyl O-(3-O-benzyl-4,6-di-O-chloroacetyl-2-deoxy-2-phthalimido-β-d-glucopyranosyl)-(1→3)-2,4,6-tri-O-benzyl-β-d-galactopyranoside (18). Removal of chloroacetyl groups gave 4,6-diol, methyl 0-(3-O-benzyl-2-deoxy-2-phthalimido-β-d-glucopyranosyl)-(1→3)-2,4,6-tri-O-benzyl-β-d-galactopyranoside (19), in which the primary hydroxy group (6-OH) was then selectively chloroacetylated to give methyl O-(3-O-benzyl-6-O-chloroacetyl-2-deoxy-2-phthalimido-β-d-glucopyranosyl)-(1→3)-2,4,6-tri-O-benzyl-β-d-galactopyranoside (20). This acceptor was then coupled with 2,4,6-tri-O-acetyl-3-O-[(S)-1-(methoxycarbonyl)ethyl]-α-d-galactopyranosyl trichloroacetimidate (14) to afford a trisaccharide, methyl O-{2,4,6-tri-O-acetyl-3-O-[(S)-l-(methoxycarbonyl)ethyl]-β-d-galactopyranosyl}-(1→4)-O-(3-O-benzyl-6-O-chloroacetyl-2-deoxy-2-phthalimido-β-d-glucopyranosyl)-(1→3)-2,4,6-tri-O-benzyl-β-d-galactopyranoside (21). Removal of the 6-O-chloroacetyl group in 21 gave 22, which was coupled with 4-O-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-2,3,6-tri-O-acetyl-α-d-glucopyranosyl trichloroacetimidate (23) to yield protected pentasaccharide 24. Standard procedures were used to remove acetyl groups and the phthalimido group, followed by N-acetylation, and debenzylation to yield pentasaccharide 27 and a hydrazide by-product (28) in a 5:1 ratio, respectively. Compound 27 contains a complete repeating unit of the capsular polysaccharide of type III group B Streptococcus in which terminal sialic acid is replaced by an (S)-1-carboxyethyl group.     

Anti-inflammatory flavanol glycosides from Saraca asoca bark

Saraca asoca (Roxb.) de Wilde, a common tree of India, is popularly used in the Ayurvedic and modern herbal systems of medicine for genito-urinary problems of women. Considering the reported antimicrobial or anti-inflammatory effect of S. asoca bark against such infections, we studied the anti-inflammatory activity-guided isolation of active compounds from methanol extract. The methanol extract of bark has yielded 10 compounds out of which 3′-deoxyepicatechin-3-O-β-d-glucopyranoside (6) and 3′-deoxycatechin-3-O-α-l-rhamnopyranoside (8) have been found to be in vitro and in vivo active. 3′,5-Dimethoxy epicatechin (3), 3′-deoxyepicatechin-3-O-β-d-glucopyranoside (6), 3′-deoxycatechin-3-O-α-l-rhamnopyranoside (8) and epigallocatechin (9) are being reported for the first time from S. asoca.     

Separation and purification of six compounds from the flowers of Cerasus yedoensis (Matsum.) by high-speed countercurrent chromatography in stepwise elution mode

Six compounds from the flower of Cerasus yedoensis (Matsum.) were successfully isolated by high-speed countercurrent chromatography (HSCCC) and preparative high performance liquid chromatography using stepwise elution with a pair of two-phase solvent systems composed of ethyl acetate–n-butanol–formic acid–water at volume ratio of 4:1.5:0.15:5 and ethyl acetate–ethanol–formic acid–water at volume ratio of 4:1:0.15:5 for the first time. This separation process produced (a) 141 mg of 1-O-caffeoyl-β-D-glucopyranoside, (b) 28 mg of p-coumaric acid glucoside, (c) 13 mg of chlorogenic acid, (d) 21 mg of quercetin-3-O-β-D-glucopyranoside, (e) 19 mg of kaempferol 3-O-β-D-glucopyranoside, and (f) 25 mg of caffeic acid from 400 mg of crude sample with the purities of 96.51, 98.82, 94.96, 99.01, 82.51, and 82.45%, respectively. MS, ¹H NMR, and ¹³C NMR analyses were used for the chemical structure identification.     

A new caffeoylgluconic acid derivative from the nearly ripe fruits of Evodia rutaecarpa

A new caffeoylgluconic acid derivative, trans-caffeoyl-6-O-d-gluconic acid methyl ester (1), together with two known compounds named trans-caffeoyl-6-O-d-glucono-γ-lactone (2) and trans-caffeoyl-6-O-d-gluconic acid (3), was isolated from the nearly ripe fruits of Evodia rutaecarpa (Juss.) Benth.. These compounds were isolated by various separation methods associated with the UPLC-Q-TOF-MS technique. Their structures were elucidated on the basis of extensive spectroscopic methods.     

SYNTHESIS OF AMINOACYL SUGAR DERIVATIVES AND THEIR TASTE CHARACTERISTICS. I. 2,3-DI- O-AMINOACYL DERIVATIVES OF ALKYL d-GLUCOPYRANOSIDES

Aminoacyl derivatives of methyl α- and β-d-glucopyranosides have been synthesized in order to ascertain the structural features required for the perception of a sweet taste. 2,3-Di-O-(l-aminoacyl) derivatives of methyl α-d-glucopyranoside showed a strong sweet taste (16–35× sucrose), which decreased or disappeared when either one of the two l-aminoacyl groups was absent or substituted by a d-aminoacyl group. In the case of 2,3-di-O-(l-alanyl) derivatives of methyl d-glucopyranoside, the α-anomer was very sweet (16–25× suc.) whereas the β-anomer was not sweet. The structural prerequisite for sweetness in this group of compounds proved to be the presence of l-aminoacyl groups at C-2 and C-3, and the α-configuration at C-1. Its α-isopropyl anomer showed the highest sweetness (64× suc.), hence the increased lipophilicity is also an important criterion.     

Assignment of the NMR Parameters of the Branch-Point Trisaccharide of Ahylopectin Using 2-D NMR Spectroscopy at 500 MHz

Abstract

The proton and carbon nuclear magnetic resonance spectroscopic data for methyl 4-O-α-d-glucopyranosyl-[6-O-a-u-glucopyranosyl]-β-d-glucopyranoside (1), a model for the branch-point trisacch-aride of amylopectin, have been analysed using 2-D-heteronuclear correlated spectroscopy. Similar data are presented for the related disaccharide structures methyl β-d-maltopyranoside and β-d-isomal topyranoside.     

SYNTHESIS OF A XYLOSYLATED RHAMNOSE PENTASACCHARIDE—THE REPEATING UNIT OF THE O-SPECIFIC SIDE CHAIN OF LIPOPOLYSACCHARIDES FROM THE REFERENCE STRAINS FOR Stenotrophomonas maltophilia SEROGROUP O18

A xylosylated rhamnose pentasaccharide, α- l-Rha p-(1→3)-[β- l-Xyl p-(1→2)-] [β- l-Xyl p-(1→4)-]α- l-Rha p-(1→3)- l-Rha p, the repeating unit of the O-specific side chain of the lipopolysaccharides from the reference strains for Stenotrophomonas maltophilia serogroup O18, was synthesized by a highly regio- and stereoselective procedure. Thus coupling of methyl rhamnopyranoside (9) with 2,3,4-tri- O-acetyl-α- l-rhamnopyranosyl trichloroacetimidate (8) gave the (1→3)-linked disaccharide (10), and subsequent benzoylation and deacetylation afforded the disaccharide acceptor 12. Condensation of 12 with 8 yielded methyl 2,3,4-tri- O-acetyl-α- l-rhamnopyranosyl-(1→3)-α- l-rhamnopyranosyl-(1→3)-2,4-di- O-benzoyl-α- l-rhamnopyranoside (13). Coupling of 13 with 2,3,4-tri- O-benzoyl-α- l-xylopyranosyl trichloroacetimidate (4) followed by deprotection gave the target pentasaccharide (15).     

SYNTHESIS OF SIALYL-α-(2→3)-NEOLACTOTETRAOSE DERIVATIVES MODIFIED AT C-2 OF THE N-ACETYLGLUCOSAMINE RESIDUE: PROBES FOR INVESTIGATION OF ACCEPTOR SPECIFICITY OF HUMAN α-1,3-FUCOSYLTRANSFERASES,FUC-TVII,AND FUC-TVI *

A variety of sialyl-α-(2→3)-neolactotetraose (IV³NeuAcnLcOse₄ or IV³NeuGcnLcOse₄) derivatives (23, 31–37, 58–60) modified at C-2 of the GlcNAc residue have been synthesized. The phthalimido group at C-2 of GlcNAc in 2-(trimethylsilyl)ethyl (3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-d-glucopyranosyl)-(1→3)-(2,4,6-tri-O-benzyl-β-d-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-d-glucopyranoside (5) was systematically converted to a series of acylamino groups, to give the per-O-benzylated trisaccharide acceptors (6–11). On the other hand, modification of the hydroxyl group at C-2 of the terminal Glc residue in 2-(trimethylsilyl)ethyl (4,6-O-benzylidene-β-d-glucopyranosyl)-(1→3)-(2,4,6-tri-O-benzyl-β-d-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-d-glucopyranoside (42) gave three different kinds of trisaccharide acceptors containing D-glucose (49), N-acetyl-d-mannosamine (50), and D-mannose (51) instead of the GlcNAc residue. Totally ten trisaccharide acceptors (5–11 and 49–51) were each coupled with sialyl-α-(2→3)-galactose donor 12 to afford the corresponding pentasaccharides (14–21 and 52–54) in good yields, respectively, which were then transformed into the target compounds. Acceptor specificity of the synthetic sialyl-α-(2→3)-neolactotetraose probes for the human α-(1→3)-fucosyltransferases, Fuc-TVII and Fuc-TVI, was examined.     

Total Asymmetric Synthesis of 5-Deoxy-5-thio-l-allose

Abstract

The optically pure Diels-Alder adduct of furan to 1-cyanovinyl (1R)-camphanate was converted to methyl(methyl 5-bromo-5-deoxy-2,3-O-isopropylidene-β-l-allo-hexo-furanosid)uronate. Ester reduction, followed by HBr elimination afforded (+)-methyl 5,6-anhydro-2,3-O-isopropylidene-d-β-talo-hexofuranoside. Applying the method of Adley and Owen, (+)-methyl 5,6-dideoxy-5,6-epithio-2,3-O-isopropylidene-l-β-allo-hexofuranoside was obtained and acetolysed to give, after deprotection, (-)-5-deoxy-5-thio-l-allose.     

A new cytotoxic diterpenoid glycoside from the leaves of Blumea lacera and its effects on apoptosis and cell cycle

A new diterpenoid glycoside, 6E,10E,14Z-(3S)-17-hydroxygeranyllinalool-17-O-β-d-glucopyranosyl-(1?→?2)-[α-l-rhamnopyranosyl-(1?→?6)]-β-d-glucopyranoside (1) together with the known diterpenoid glycoside (2) and two known flavonoid glycosides (3, 4) were isolated from the methanol extract of Blumea lacera leaves. The structures were determined by the interpretation of their spectroscopic data and comparison with the literature. All compounds were isolated for the first time from B. lacera and evaluated for their cytotoxic activity. Only the new compound (1) showed strong cytotoxic activity with the lowest IC₅₀ value (8.3 μM) being displayed against MCF-7 breast cancer cells. In apoptosis and cell cycle analysis, 1 revealed strong apoptotic activity against MCF-7 cells (45.5% AV⁺/PI^?) after 24 h, but showed no arresting of any of the cell cycle phases in MCF-7.