Lignan, phenolic and iridoid glycosides from Stereospermum cylindricum

A lignan glycoside [(+)-cycloolivil 4'-O-beta-d-glucopyranoside], a phenolic glycoside [3,4-dimethoxyphenyl 1-O-beta-d-xylopyranosyl-(1-->6)-beta-d-glucopyranoside] and a iridoid glycoside (stereospermoside) were isolated from the leaves and branches of Stereospermum cylindricum, together with (+)-cycloolivil, (+)-cycloolivil 6-O-beta-d-glucopyranoside, (-)-olivil, (-)-olivil 4-O-beta-d-glucopyranoside, (-)-olivil 4'-O-beta-d-glucopyranoside, vanilloloside, decaffeoyl-verbascoside, isoverbascoside, 3,4,5-trimethoxyphenyl 1-O-beta-d-xylopyranosyl-(1-->6)-beta-d-glucopyranoside, ajugol, verminoside, and specioside. The structure elucidations were based on spectroscopic evidence.     

Sublethal effects of resin glycosides from the periderm of sweetpotato storage roots on Plutella xylostella (Lepidoptera: Plutellidae)

Resin glycoside material extracted from the periderm tissue of storage roots from sweetpotato, Ipomoea batatas (L.) Lam., was bioassayed for effects on survival, development, and fecundity of the diamondback moth, Plutella xylostella (L.). The resin glycoside was incorporated into an artificial diet and fed to P. xylostella larvae. First instars were placed individually into snap-top centrifuge vials containing artificial diet with one of six concentrations of resin glycoside material (0.00, 0.25, 0.50, 1.00, 1.50, and 2.00 mg/ml). Each replication consisted of 10 individuals per concentration, and the experiment was repeated 13 times. Vials were incubated at 25 degrees C and a photoperiod of 14:10 (L:D) h in a growth chamber. After 6 d, surviving larvae were weighted and their sex determined, then returned to their vials. Later, surviving pupae were weighed and incubated at 25 degrees C until moths emerged. Females were fed, mated with males from the laboratory colony, and allowed to lay eggs on aluminum foil strips. Lifetime fecundity (eggs/female) was measured. There were highly significant negative correlations between resin glycoside levels and survival, and between glycoside levels and larval weight after 6 d of feeding. For larvae that lived at least 6 d, there was no additional mortality that could be attributed to the resin glycoside material. However, there was a significant positive correlation between glycoside dosages and developmental time of larvae (measured as days until pupation). Lifetime fecundity also was negatively affected at sublethal doses. Resin glycosides may contribute to the resistance in sweetpotato breeding lines to soil insect pests.     

Glycosides from Phlomis lunariifolia

An aliphatic alcohol glycoside, lunaroside 1-octen-3-yl [O-beta-apiofuranosyl-(1-->6)-O-[beta-glucopyranosyl-(1-->2)]-beta-glucopyranoside, a phenylethanoid glycoside, lunariifolioside 2-(3,4-dihydroxyphenyl)ethylO-beta-apiofuranosyl-(1-->6)-O-[O-beta-apiofuranosyl-(1-->4)-alpha-rhamnopyranosyl-(1-->3)]-4-O-(E)-caffeoyl-beta-glucopyranoside and a flavone glycoside, luteolin 7-O-[4-O-acetyl-alpha-rhamnopyranosyl-(1-->2)]-beta-glucuronopyranoside, were isolated from the aerial parts of Phlomis lunariifolia, in addition to 15 known glycosides. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic interpretation and chemical degradation.     

Coumaroyl triterpene lactone, phenolic and naphthalene glycoside from stem bark of Diospyros angustifolia

From the ethanolic extract of stem bark of D. angustifolia three new compounds, a coumaroyl triterpene lactone, diospyrosooleanolide (1), a phenolic glycoside, diospyrososide (2) and a naphthalene glycoside, diospyrosonaphthoside (3) were isolated along with five known compounds (4-8). The structures of these compounds were established on the basis of spectroscopic and chemical evidences.     

Phenolic glycosides from Symplocos racemosa: natural inhibitors of phosphodiesterase I

One new phenolic glycoside named benzoylsalireposide (1) along with one known phenolic glycoside named salireposide (2) have been isolated from Symplocos racemosa. Four other known compounds i.e. beta-amyrin (3), oleonolic acid (4), beta-sitosterol (5) and beta-sitosterol glycoside (6) were also isolated from this plant. The structure elucidation of the isolated compounds was based primarily on 1D- and 2D-NMR analysis, including COSY, HMQC, and HMBC correlations. The compound 1 and 2 showed inhibitory activity against snake venom phosphodiesterase I.     

Iridoid and bisiridoid glycosides from Globularia cordifolia

From the methanolic extract of the underground parts of Globularia cordifolia, a new iridoid glycoside, 5-hydroxydavisioside (1) and a new bisiridoid glycoside, globuloside C (2) were isolated along with six known iridoid glycosides, aucubin, melampyroside, monomelittoside, globularifolin, alpinoside and asperuloside. The structures of the isolates were established by 1D and 2D NMR spectroscopy in combination with IR, UV and MS analyses.     

Phenylethanoid and aliphatic alcohol glycosides from Acanthus ilicifolius

A phenylethanoid glycoside (ilicifolioside A) and an aliphatic alcohol glycoside (ilicifolioside B), have been isolated from the aerial parts of Acanthus ilicifolius, together with eight known compounds. Their structures were determined from spectroscopic analyses.     

Iridoid and phenolic glycosides from Wulfenia carinthiaca

Two new phenylpropanoid glycosides (2'-O-acetylplantamajoside and 2'-O, 6"-O-diacetylplantamajoside), a new iridoid glycoside (10-O-(cinnamoyl)-6'-O-(desacetylalpinosidyl)-catalpol), the two known iridoid glycosides globularin and isoscrophularioside, and the known phenylpropanoid glycoside platamajoside were isolated from the methanolic extract of the underground parts of Wulfenia carinthiaca. Structure elucidations were based on high-resolution mass spectrometry and extensive 1-D and 2-D NMR spectroscopy.     

Synthesis and biological activity of anomeric muramoyldipeptide butylglycosides

The synthesis of anomeric butyl glycosides of muramyl dipeptide was reported. alpha-Butyl glycoside of N-acetyl-D-glucosamine was 4,6-O-benzylidenated and the benzylidene derivative was 3-O-alkylated by the Williamson reaction with sodium (S)-2-chloropropionate. The resulting protected alpha-butyl glycoside of muramic acid was then condensed with L-Ala-D-iGln-OBzl by the DCC-HOSu method. Mild acidic hydrolysis and subsequent catalytic hydrogenolysis of the resulting glycopeptide yielded the target alpha-butyl glycoside of N-acetyl-L-alanyl-D-isoglutamine. In the synthesis of beta-butyl glycoside of N-acetylmuramyl-L-alanyl-D-isoglutamine, 2-acetamido- 4,6-di-O-acetyl-2-deoxy-3-O-[(R)-1-(methoxycarbonyl)ethyl]-alpha- D-glucopyranose, a 1-OH derivative of muramic acid, was the key compound. Its interaction with the excess thionyl chloride resulted in the corresponding glycosyl halide, which was condensed with n-butanol according to Helferich. O-Deacetylation, 4,6-isopropylidenation, and subsequent alkaline hydrolysis of the resulting compound gave the protected beta-butyl glycoside of muramic acid. Its activation and condensation with L-Ala-D-iGln-OBzl and the subsequent removal of protective groups were performed in the same manner as the reactions in the synthesis of alpha-butyl glycoside of N-acetyl-L-alanyl-D-isoglutamine. The adjuvant activity of the butyl glycosides to HIV proteins rgp160 and rgp120 and their ability to affect in vitro HIV replication and the proliferation of mouse spleen T-cells were examined. The biological activity of anomeric muramyl dipeptides was shown to depend essentially on the configuration of their anomeric center.     

Bitter phenylpropanoid glycosides from Conandron ramoidioides

A new bitter glycoside, conandroside and a known glycoside, acteoside were isolated from Conandron ramoidioides. On the basis of the chemical and spectral evidence, conandroside was shown to be 2-(3′,4′-dihydroxy-phenyl)-ethanol 1-O-β-D-xylosyl-(1 → 3)-β-D-(4-caffeyl)-glucoside.     

Flavonol glycosides from the stems of Trigonella foenum-graecum

Two kaempferol glycosides [kaempferol 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside 7-O-beta-D-glucoside and kaempferol 3-O-beta-D-glucosyl(1-->2)-(6"-O-acetyl)-beta-D-galactoside 7-O-beta-D-glucoside] as well as the quercetin glycoside [quercetin 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside 7-O-beta-D-glucoside] were isolated from the stems of Trigonella foenum-graecum L. (Leguminosae) along with a known kaempferol glycoside, lilyn [kaempferol 3-O-beta-D-glucosyl(1-->2)-beta-D-galactoside]. Their structures were established by analysis of chemical and spectral evidence.     

半制备高效液相色谱制备5种苯乙醇苷类单体

利用MCI柱层析和半制备型反相高效液相色谱法从牛耳朵中分离制备了5种苯乙醇苷类单体。在Eclipse XDB-C18(9.4mm×250mm,5μm)半制备柱上,以甲醇-水为流动相,流速为4mL/min,采用梯度洗脱方式,制备得到5个组分。经波谱(EI-MS、1H-NMR、13C-NMR)分析,分别鉴定为plantainoside(1)、chirito-sideC(2)、plantaninosideB(3)、plantamajoside(4)和desrhamnosylverbascoside(5)。高效液相色谱分析表明所制备5种化合物纯度均高于98%。该方法分离条件简单,高效,一次可得到5个单体,目标产物纯度较高。     

New steroidal glycosides from rhizomes of Clintonia udensis

A total of 10 steroidal glycosides, together with three new spirostanol glycosides (6-8), a new furostanol glycoside (9), and a new cholestane glycoside (10), were isolated from the rhizomes of Clintonia udensis (Liliaceae). The structures of the new compounds were determined on the basis of extensive spectroscopic analyses, including 2-D nuclear magnetic resonance (NMR) data, and of hydrolytic cleavage followed by chromatographic or spectroscopic analyses. The isolated glycosides were evaluated for their cytotoxic activity against HL-60 leukemia cells. Spirostanol glycosides 1 and 2, and furostanol glycoside 4 showed cytotoxic activity with IC(50) values of 3.2+/-0.02, 2.2+/-0.12, and 2.2+/-0.06 microg/ml, respectively. Neither the spirostanol and furostanol saponins with a hydroxy group at C-1 (6 and 9) and C-12 (7 and 8) nor cholestane glycosides (5 and 10) exhibited apparent cytotoxic activity at a sample concentration of 10 microg/ml.     

Synthesis and immunological evaluation of the 4-β-glucoside of HMBPP

HMBPP ((E)-4-hydroxy-3-methyl-2-butenyl pyrophosphate) is a highly potent innate immunogen that stimulates human γδ T cells expressing the Vγ2Vδ2 T cell antigen receptor. To determine if glycoside conjugates of HMBPP retain activity, the 4-β-glucoside and its acetylated homolog were synthesized and tested for their ability to stimulate γδ T cells. The glycoside HMBPP conjugate stimulated human γδ T cells with an EC(50) of 78nM. The tetraacetyl glycoside HMBPP conjugate was also active (EC(50)=360nM). The two isomeric mono-β-glucosides of the parent (E)-2-methylbut-2-ene-1,4-diol, however, were not active. Thus, HMBPP glycosylated at the 4-OH position stimulates γδ T cells as long as the pyrophosphate moiety is present.     

Pinpointing the sites of hydroxylysine glycosides in peptide alpha 1-CB7 of bovine corneal collagen, and their possible role in determining fibril diameter and thus transparency

Two cyanogen bromide fragments (alpha 1-CB7 and alpha 1-CB8) of bovine corneal stromal collagen have been isolated and characterized. These added to those characterized in our previous work account for 95% of the amino acid sequence of the alpha 1(1)-chain. The hydroxylysine glycoside content of each fragment was determined and in this way the general distribution of glycoside over the entire molecule was deduced accounting for all the galactosylhydroxylysine and most of the glucosylgalactosylhydroxylysine of this heavily glycosylated type I collagen. The characterization of fragments alpha 1-CB7 and alpha 1-CB8 has enabled us to resolve the controversy over the relative mobilities of these fragments on SDS gels. Fragment alpha 1-CB7 of bovine corneal collagen was digested by trypsin and by staphylococcal proteinase V8. The resultant peptides were isolated by gel and ion-exchange chromatography and identified in relation to the known amino acid sequence of type I collagen. The hydroxylysine glycosides were determined in the relevant peptides providing a complete account of their distribution along this part of the collagen molecule. Most of the glycoside was found in the gap region of collagen especially near the edges of the axial holes where it could act as a peg to facilitate fibre formation. In addition, some glycoside was found in the overlap region where, being unable to fit into axial holes, it might impede the growth of the fibre and, with other glycoside of the overlap region, might be responsible for the narrow fibres of corneal collagen that are essential for corneal transparency. This glycoside, with that previously found in the peptide alpha 1-CB3 is the only hydroxylysine glycoside identified in the overlap region of a type I collagen.     

Monoterpene and lignan glycosides in the leaves of Crataegus pinnatifida

In the present phytochemical study on the leaves of Crataegus pinnatifida, a new monoterpene glycoside, (3S,5R,6R,7E,9R)-3,6-epoxy-7-megastigmen-5,9-diol-9-O-β-Dglucopyranoside(6) and a new sesquilignan glycoside, acernikol-4’’-O-β-D-glucopyranoside (15), together with thirteen known compounds were isolated.     

Molecular design of fluorescent labeled glycosides as acceptor substrates for sialyltransferases

A series of dansyl-labeled glycosides with di-, tetra-, and hexasaccharides carrying the terminal N-acetyllactosamine (LacNAc) sequence were synthesized as acceptor substrates for α2,6- and α2,3-sialyltransferases. As an alternative design, dansyl-labeled LacNAc glycoside carrying a long-spacer linked glycan was engineered by replacement of the LacNAc or lactose units with an alkyl chain. In addition, we designed a dansyl-labeled bi-antennary LacNAc glycoside as an N-linked oligosaccharide mimetic, such as asialo-α(1)-acid glycoprotein. The kinetic parameters for the transfer reaction of synthesized dansyl-labeled glycosides by sialyltransferases were determined by the fluorescent HPLC method. The catalytic efficiencies (V(max)/K(m)) of acceptor substrates carrying the terminal LacNAc sequence with various length glycans in the array for α2,6- and α2,3-sialyltransferases decreased in a glycan length-dependent manner. Furthermore, of the acceptor substrates tested, dansyl-labeled bi-antennary LacNAc glycoside displayed the most favorable K(m) value for α2,6- and α2,3-sialyltransferases.     

Effect of O-glycosilation on the antioxidant activity and free radical reactions of a plant flavonoid,chrysoeriol

Chrysoeriol and its glycoside (chrysoeriol-6-O-acetyl-4'-beta-D-glucoside) are two natural flavonoids extracted from the tropical plant Coronopus didymus. The aqueous solutions of both the flavonoids were tested for their ability to inhibit lipid peroxidation induced by gamma-radiation, Fe (III) and Fe (II). In all these assays chrysoeriol showed better protecting effect than the glycoside. The compounds were also found to inhibit enzymatically produced superoxide anion by xanthine/xanthine oxidase system; here the glycoside is more effective than the aglycone. The rate constants for the reaction of the compounds with superoxide anion determined by using stopped-flow spectrometer were found to be nearly same. Chrysoeriol glycoside reacts with DPPH radicals at millimolar concentration, but the aglycone showed no reaction. Using nanosecond pulse radiolysis technique, reactions of these compounds with hydroxyl, azide, haloperoxyl radicals and hydrated electron were studied. The bimolecular rate constants for these reactions and the transient spectra of the one-electron oxidized species indicated that the site of oxidation for the two compounds is different. Reaction of hydrated electron with the two compounds was carried out at pH 7, where similar reactivity was observed with both the compounds. Based on all these studies it is concluded that chrysoeriol exhibits potent antioxidant activity. O-glycosylation of chrysoeriol decreases its ability to inhibit lipid peroxidation and reaction with peroxyl radicals. However the glycoside is a more efficient scavenger of DPPH radicals and a better inhibitor of xanthine/xanthine oxidase than the aglycone.     

Controlling selectivity and enhancing yield of flavonoid glycosides in recombinant yeast

Flavonoid glycosides are known for their medicinal properties and potential use as natural sweeteners. In this study, Saccharomyces cerevisiae expressing a flavonoid glucosyltransferase from Dianthus caryophyllus was used as a whole-cell biocatalyst. The yeast system’s performance was characterized using the flavanone naringenin as a model substrate for the production of naringenin glycosides. It was found that final naringenin glycoside yields increased in a dose-dependent manner with increasing initial naringenin substrate concentrations. However, naringenin concentrations >0.5 mM did not give further enhancements in glycoside yield. In addition, a method for controlling overall selectivity was discovered where the glucose content in the culture medium could be altered to control the selectivity, making either naringenin-7-O-glucoside (N7O) or naringenin-4′-O-glucoside (N4O) the major products. The highest yields achieved were 87 mg/L of N7O and 82 mg/L of N4O using 40MSGI and 2xMSGI media, respectively. The effects of two intermediates involved in UDP-glucose biosynthesis, uridine 5′-monophosphate (UMP) and orotic acid, on glycoside yields were also determined. Addition of UMP to the culture medium significantly decreased glycoside yield. In contrast, addition of orotic acid to the culture medium significantly enhanced the glycoside yield and shifted the selectivity toward N7O. The highest naringenin glycoside yield achieved using 10 mM orotic acid in the 40MSGI media was 155 mg/L, a 71% conversion of substrate to product.     

Evidence for different glycohydrolase and glycosyltransferase activities of beta-N-acetylglucosaminidases A and B.

1) Two forms of beta-N-acetylglucosaminidase--known as form A and form B - were purified from bovine spleen homogenates and efficaciously separated by preparative disc electrophoresis on polyacrylamide gel. Studies on the enzymatic specificity revealed that the two forms have different glycoside hydrolase and glycosyl transferase activities towards substrates of natural origin. 2) With the trisaccharide GlcNAc-GlcUA-GlcNAc from hyaluronate as substrate, form A released free N-acetylglucosamine at a rate 35-40 times higher than form B. The B form, however, transferred N-acetyl-[6-3H]glucosamine from phenyl-beta-N-acetyl-D[6-3H]glucosaminide to the tetrasaccharides GlcUA-GalNAc-4-sulfate-GlcUA--GalNAc-4-sulfate or GlcUA-GlcNAc-GlcUA-GlcNAc isolated from chondroitin 4-sulfate or hyaluronate at rates 5-10 times higher than beta-N-acetyl-glucosaminidase A, the corresponding 3H-pentasaccharides being isolated as reaction products. 3) The pH optimum of the glycoside hydrolase activity is 4.5, while optimum glycosyl transfer proceeds at pH 6.5. Under condition optimum for glycoside transferase, hydrolytic activity is still observed with each form, but the B form exhibits about equal glycoside hydrolase and glycoside transferase activity, whereas the A form has a predominant glycoside hydrolase action.