8-Hydroxyflavonoid glucuronides of <Emphasis Type="Italic">Malope trifida</Emphasis>

The new flavonoid: herbacetin 3-O-β-glucopyranoside-8-O-β-glucuronopyranoside (1) together with known gossypetin 3-O-β-glucopyranoside - 8-O-β-glucuronopyranoside (2) and isoscutellarein: 8-O-β-glucuronopyranoside (3) as well as 4′-methyl ether-8-O-β-glucuronopyranoside (4), were isolated from the calyx and epicalyx leaves of Malope trifida and identified on the basis of their spectroscopic properties: UV, ¹H and ¹³C NMR, ESI/MS. Two other flavonoids were identified as isoscutellarein: 3′-hydroxy 4′-methyl ether-8-O-β-glucuronoside (5) and 8-O- rhamnoglucoside (6) on the basis of their UV and ESI/MS data.     

Chemosystematic investigations on phenolics from flowerheads of Central European taxa of Hieracium sensu lato (Asteraceae)

 HPLC-UV and HPLC-MS investigations of phenolic acids and flavonoids in flowerheads of 84 samples of 76 taxa belonging to 66 species of Hieracium resulted in the identification of three phenolic acids (chlorogenic acid, 3,5-dicaffeoyl quinic acid, 4,5-dicaffeoyl quinic acid) and six flavonoids (apigenin 4^′-O-β-D-glucuronide, isoetin 4^′-O-β-D-glucuronide, luteolin, luteolin 7-O-β-D-glucoside, luteolin 7-O-β-D-glucuronide, luteolin 4^′-O-β-D-glucoside). The contents of these secondary metabolites were quantified by HPLC using quercetin and cynarin as internal standards. In contrast to the previously investigated genera Leontodon and Crepis, cichoric acid and caffeoyl tartaric acid were not found in any of the investigated Hieracium taxa. Results of HPLC analyses revealed only a limited degree of qualitative variation between the different taxa, and luteolin 7-O-β-D-glucuronide and isoetin 4^′-O-β-D-glucuronide were the only compounds, which were not detectable in some of the investigated taxa. Quantitative patterns of phenolics differed markedly between particular taxa and Principal Component Analysis of the quantification results yielded separate clusters for the members of the subgenera Hieracium and Pilosella. Received January 23, 2001 Accepted October 11, 2001     

Accumulation of cyclohexenone derivatives in barley, wheat and maize roots in response to inoculation with different arbuscular mycorrhizal fungi

Glomus intraradices , Glomus mosseae, and Gigaspora rosea leads to the accumulation of cyclohexenone derivatives. Mycorrhizal roots of all plants accumulate in response to all three fungi blumenin [9-O-(2′-O-glucuronosyl)-β-glucopyranoside of 6-(3-hydroxybutyl)-1,1,5-trimethyl-4-cyclohexen-3-one], 13-carboxyblumenol C 9-O-gentiobioside, nicoblumin [9-O-(6′-O-β-glucopyranosyl)-β-glucopyranoside of 13-hydroxy-6-(3-hydroxybutyl)-1,1,5-trimethyl-4-cyclohexen-3-one] and another, as yet unidentified, cyclohexenone derivative. The accumulation of all four compounds in three tested mycorrhizal plants colonized by the three arbuscular mycorrhizal fungi indicates no fungus-specific induction of these compounds. Accepted: 6 October 1999     

Structures and cytotoxic activities of two new asterosaponins from the antarctic starfish <Emphasis Type="Italic">Diplasterias brucei</Emphasis>

Two new asterosaponins, diplasteriosides A and B, bearing the same β-D-Fucp-(1→2)-β-D-Galp-(1→4)-[β-D-Quip-(1→2)]-β-D-Quip-(1→3)-β-D-Quip-(1→ oligosaccharide chains linked to the C6 atom of the known genins, 3-O-sulfates of thornasterols A and B, respectively, were isolated from the Antarctic Diplasterias brucei starfish along with the previously known asteriidoside A. The structures of the new compounds were elucidated by two-dimensional NMR spectroscopy and mass spectrometry. Cytotoxicities of the isolated asterosaponins against the human colon cancer HCT-116, human breast cancer T-47D cell line, and human melanoma cancer RPMI-7951 cell lines were studied.     

Microbial transformation of ginsenoside Rb<Subscript>1</Subscript> by <Emphasis Type="Italic">Acremonium strictum</Emphasis>

Preparative-scale fermentation of ginsenoside Rb₁ (1) with Acremonium strictum AS 3.2058 gave three new compounds, 12β-hydroxydammar-3-one-20 (S)-O-β-d-glucopyranoside (7), 12β, 25-dihydroxydammar-(E)-20(22)-ene-3-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranoside (8), and 12β, 20 (R), 25-trihydroxydammar-3-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranoside (9), along with five known compounds, ginsenoside Rd (2), gypenoside XVII (3), ginsenoside Rg₃ (4), ginsenoside F₂ (5), and compound K (6). The structural elucidation of these metabolites was based primarily on one- and two-dimensional nuclear magnetic resonance and high-resolution electron spray ionization mass spectra analyses. Among these compounds, 2–6 are also the metabolites of ginsenoside Rb₁ in mammals. This result demonstrated that microbial culture parallels mammalian metabolism; therefore, A. strictum might be a useful tool for generating mammalian metabolites of related analogs of ginsenosides for complete structural identification and for further use in pharmaceutical research in this series of compounds. In addition, the biotransformation kinetics was also investigated.     

A new acylated flavonol diglycoside from <Emphasis Type="Italic">Atriplex littoralis</Emphasis>

A new acetylated flavonol glycoside: patuletin 3-O-[5′″-O-feruloyl-β-D-apiofuransyl (1′″→2′′)-β-D-glucopyranoside] (2), together with a known patuletin 3-O-β-D-glucopyranoside (1) were isolated from the aerial part of Artiplex littoralis L. (Chenopodiacease). Their structures were elcidated by acid hydrolysis and spectroscopic methods including UV, ¹H, ¹³C NMR and ESI-MS for both compounds, additionally 2D-NMR, HSQC, HMBC experiments were performed for 2.     

A novel isoflavone glycoside fromCaragana alaica

3-O-Rhamnopyranosylisorhamnetin, 3-O-glucopyranosylisorhamnetin, 7-O-galactopyranosylluteolin, quercitrin, isoquercitrin, wistin, and a novel isoflavonoid, 3′-hydroxy-6,4′-dimethoxy-7-O-β-D-glucopyranosylisoflavone, were isolated from the aerial parts ofaragana alaica. Of these, the previously described compounds were identified on the basis of their physicochemical and spectral characteristics, whereas the spectral analysis and conversion to a known compound, cladrastin, allowed the structural elucidation of the novel isoflavone glycoside.     

Synthesis of a new neoglycopeptide for inhibition of lactose permease. Dedicated to Professor Fritz Jähnig,who inspired this work

Summary A new neoglycopeptide was synthesized and tested for its capability to bind to lactose permease ofEscherichia coli and to inhibit the transport of lactose. The free 5′-carboxypentyl-1-thio-β-d-galactopyranoside or the protected 2,3,4,6-tetra-O-acetyl-5′-carboxypentyl-1-thio-β-d-galactopyranoside was linked to the N-terminal α-amino group of the resin bound heptapeptide H-Phe-Phe-Gly-Gly-Gly-Gly-Ala-OH by different activation methods. Upon cleavage from the resin, deacetylation and purification, a neoglycopeptide which showed a significant inhibition of lactose permease was obtained.     

Presence of supercooling-facilitating (anti-ice nucleation) hydrolyzable tannins in deep supercooling xylem parenchyma cells in <Emphasis Type="Italic">Cercidiphyllum japonicum</Emphasis>

Xylem parenchyma cells (XPCs) in trees adapt to subzero temperatures by deep supercooling. Our previous study indicated the possibility of the presence of diverse kinds of supercooling-facilitating (SCF; anti-ice nucleation) substances in XPCs of katsura tree (Cercidiphyllum japonicum), all of which might have an important role in deep supercooling of XPCs. In the previous study, a few kinds of SCF flavonol glycosides were identified. Thus, in the present study, we tried to identify other kinds of SCF substances in XPCs of katsura tree. SCF substances were purified from xylem extracts by silica gel column chromatography and Sephadex LH-20 column chromatography. Then, four SCF substances isolated were identified by UV, mass and nuclear magnetic resonance analyses. The results showed that the four kinds of hydrolyzable gallotannins, 2,2′,5-tri-O-galloyl-α,β-d-hamamelose (trigalloyl Ham or kurigalin), 1,2,6-tri-O-galloyl-β-d-glucopyranoside (trigalloyl Glc), 1,2,3,6-tetra-O-galloyl-β-d-glucopyranoside (tetragalloyl Glc) and 1,2,3,4,6-penta-O-galloyl-β-d-glucopyranoside (pentagalloyl Glc), in XPCs exhibited supercooling capabilities in the range of 1.5–4.5°C, at a concentration of 1 mg mL⁻¹. These SCF substances, including flavonol glycosides and hydrolyzable gallotannins, may contribute to the supercooling in XPCs of katsura tree.     

The structure of sulfated cauloside C

The structure of the sulfated analogue of cauloside C, a biologically active triterpenoid glycoside, was elucidated to be 3-O-[β-D-glucopyranosyl-(1→2)-α-L-arabinopyranosyl]-hederagenin 23,4′,4″,6″-tetrasulfate pentasodium salt by the comparison of its¹³C NMR spectrum with that of cauloside C potassium salt.     

Extracellular monoenzyme deglycosylation system of 7-O-linked flavonoid β-rutinosides and its disaccharide transglycosylation activity from Stilbella fimetaria

We screened for microorganisms able to use flavonoids as a carbon source; and one isolate, nominated Stilbella fimetaria SES201, was found to possess a disaccharide-specific hydrolase. It was a cell-bound ectoenzyme that was released to the medium during conidiogenesis. The enzyme was shown to cleave the flavonoid hesperidin (hesperetin 7-O-α-rhamnopyranosyl-β-glucopyranoside) into rutinose (α-rhamnopyranosyl-β-glucopyranose) and hesperetin. Since only intracellular traces of monoglycosidase activities (β-glucosidase, α-rhamnosidase) were produced, the disaccharidase α-rhamnosyl-β-glucosidase was the main system utilized by the microorganism for hesperidin hydrolysis. The enzyme was a glycoprotein with a molecular weight of 42224 Da and isoelectric point of 5.7. Even when maximum activity was found at 70°C, it was active at temperatures as low as 5°C, consistent with the psychrotolerant character of S. fimetaria. Substrate preference studies indicated that the enzyme exhibits high specificity toward 7-O-linked flavonoid β-rutinosides. It did not act on flavonoid 3-O-β-rutinoside and 7-O-β-neohesperidosides, neither monoglycosylated substrates. In an aqueous medium, the α-rhamnosyl-β-glucosidase was also able to transfer rutinose to other acceptors besides water, indicating its potential as biocatalyst for organic synthesis. The monoenzyme strategy of S. fimetaria SES201, as well as the enzyme substrate preference for 7-O-β-flavonoid rutinosides, is unique characteristics among the microbial flavonoid deglycosylation systems reported.     

Isolation and potential cancer chemopreventive activities of phenolic compounds of beer

Beer contains a variety of phenolic compounds. During the brewing process, some of these compounds are removed by polyvinylpolypyrrolidone (PVPP) to prevent haze formation. We have analyzed the phytochemical composition of a PVPP residue as well as of unstabilized beer and isolated a total of 51 compounds. Eight structures were identified as novel, i.e., 2-(4′-hydroxyphenyl)-3,5-dihydroxybenzoic acid (6), 2′-(4″-hydroxyphenyl)isoferulic acid ester (12), 1,2,5,7-tetrahydroxyanthraquinone (23) and 4,7-dihydroxy-5-(2′,4′,6′-trihydroxyphenyl)-indan-1,2-dione (24) from the PVPP residue, and catechin-7-O-β-(6″-O-nicotinoyl)-β-D-glucopyranoside (41), ent-epigallo-catechin-(4αto8, 2αtoOto7)catechin (44), ent-epigallocatechin (4αto6, 2αtoOto7)catechin (45) and 2,3-cis-3,4-trans-2-[2,3-trans-3,3′,4′,5,7-pentahydroxyflavan-8-yl]-4-(3,4-dihydroxyphenyl)3,5,7-trihydroxybenzopyran (46) from the unstabilized beer. Most of the compounds were tested for potential cancer chemopreventive activities in in vitro test systems detecting a modulation of carcinogen metabolism (inhibition of phase 1 cytochrome P450 1A (Cyp1A) activity, induction of NAD(P)H:quinone oxidoreductase (QR) activity) and anti-inflammatory mechanisms (inhibition of lipopolysaccharide (LPS)-mediated induction of inducible nitric oxide synthase (iNOS), inhibition of cyclooxygenase 1 (Cox-1) activity). 1,2,5,7-Tetrahydroxyanthraquinone (23) and xanthohumol (25), a prenylated chalcone derived from hop, were identified as the most potent compounds and were additionally tested for inhibition of chemically-induced preneoplastic lesions in an ex vivo mouse mammary gland organ culture model (MMOC). Importantly, both agents inhibited lesion formation with halfmaximal inhibitory concentrations (IC₅₀) of 0.1 and 0.02 μM, respectively. Our results demonstrate that beer is an interesting source of potential cancer chemopreventive agents and should be further investigated with this respect. This revised version was published online in June 2006 with corrections to the Cover Date.     

A new β-galactosidase with a low temperature optimum isolated from the Antarctic <Emphasis Type="Italic">Arthrobacter</Emphasis> sp. 20B: gene cloning,purification and characterization

A psychrotrophic bacterium producing a cold-adapted β-galactosidase upon growth at low temperatures was classified as Arthrobacter sp. 20B. A genomic DNA library of strain 20B introduced into Escherichia coli TOP10F′ and screening on X-Gal (5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside)-containing agar plates led to the isolation of β-galactosidase gene. The β-galactosidase gene (bgaS) encoding a protein of 1,053 amino acids, with a calculated molecular mass of 113,695 kDa. Analysis of the amino acid sequence of BgaS protein, deduced from the bgaS ORF, suggested that it is a member of the glycosyl hydrolase family 2. A native cold-adapted β-galactosidase was purified to homogeneity and characterized. It is a homotetrameric enzyme, each subunit being approximately 116 kDa polypeptide as deduced from native and SDS–PAGE, respectively. The β-galactosidase was optimally active at pH 6.0–8.0 and 25°C. P-nitrophenyl-β-d-galactopyranoside (PNPG) is its preferred substrate (three times higher activity than for ONPG—o-nitrophenyl-β-d-galactopyranoside). The Arthrobacter sp. 20B β-galactosidase is activated by thiol compounds (53% rise in activity in the presence of 10 mM 2-mercaptoethanol), some metal ions (activity increased by 50% for Na⁺, K⁺ and by 11% for Mn²⁺) and inactivated by pCMB (4-chloro-mercuribenzoic acid) and heavy metal ions (Pb²⁺, Zn²⁺, Cu²⁺).     

Note: Characterisation of furcellaran samples from Estonian <Emphasis Type="Italic">Furcellaria lumbricalis</Emphasis> (Rhodophyta)

The structure of furcellarans obtained from red algae Furcellaria lumbricalis collected in Estonia was determined. Native and alkali-modified furcellarans were examined by gas chromatography/mass spectrometry (GC/MS), and ¹³C-nuclear magnetic resonance spectroscopy (NMR) and were compared with commercial furcellaran (FMC Food Ingredients). The polysaccharide preparation consisted mainly of (1→3) linked β-D-galactopyranose, (1→4) linked 3,6-anhydro-α-D-galactopyranose and (1→3) linked β-D-galactopyranose 4-sulphate. Alkaline treatment removed the sulphate precursor sequences with formation of 3,6-anhydrogalactose that improved the furcellaran gelling ability.     

Microchemical analysis of laser-microdissected stone cells of Norway spruce by cryogenic nuclear magnetic resonance spectroscopy

Stone cells (sclereids) in Norway spruce (Picea abies) bark have been reported to be highly lignified tissues that are important in physical defence against bark beetle invasion. Microchemical analyses of the low-molecular weight compounds in the stone cells of Norway spruce were carried out using laser microdissection in combination with cryogenic nuclear magnetic resonance and mass spectrometry (LMD/NMR/MS). Two phenolic compounds, the stilbene astringin and the dihydroflavonol dihydroxyquercetin 3′-O-β-d-glucopyranoside, were identified indicating that stone cells are more than just repositories for lignin. Both of these compounds were also found to be present in other phloem tissue at a higher level than in the stone cells based on quantification by cryogenic ¹H NMR. Our results suggest that stone cells may be involved in chemical as well as physical defense against bark beetles and their associated microorganisms. This paper reports on the identification of secondary plant metabolites from a single laser-microdissected population of plant cells offering a sensitive new way to determine the chemical profile of specific plant cell types with a high degree of precision.     

Biotransformation of eugenol by suspension cultures of transgenic crown galls of <Emphasis Type="Italic">Panax quinquefolium</Emphasis> and suspension cultures of <Emphasis Type="Italic">Nicotiana tabacum</Emphasis>

The biocatalytic ability of transgenic crown galls of Panax quinquefolium was evaluated by using eugenol (1) as a substrate and suspension cultures of Nicotiana tabacum as control system. Three biotransformed products, namely: 2-methoxy-4-(2-propenyl)phenyl-O-β-d-glucopyranoside (2, 67.11%), 2-methoxy-4-(2-propenyl)phenyl-O-β-d-glucopyranosyl (6′ → 1″)-β-d-xylopyranoside (3, 2.85%) and methyl eugenol (4, 14.30%) were obtained after 5 days of administration of eugenol to the suspension cultures of transgenic crown galls of P. quinquefolium. In contrast, only one product, compound 2 (15.41%), was obtained in suspension cultures of N. tabacum after 5 days of incubation. The results indicated that the glycosylation ability of transgenic crown galls of P. quinquefolium was much higher than that of the cultured cells of N. tabacum.     

Low-Molecular-Weight Compounds

Self-association of caffeine has been investigated using mass spectrometry. It was found that associates are composed of caffeine trimers and hexamers. The possibility of complex formation of caffeine with triterpene glycosides 3-O-α-L-rhamnopyranosyl-(1→2)-O-α-L-arabinopyranoside of hederagenin and its 28-O-α-L-rhamnopyranosyl-(1→4)-O-β-D-glucopyranosil-(1→6)-O-β-D-glucopyranosil ester have been considered. Under the experimental conditions, inclusion compounds do not form and only self-associates of caffeine and glycosides are found.     

Canna indica flower: New source of anthocyanins

In this study the red flowers of Canna indica (Cannaceae) were extracted by using sonicator and isolation of anthocyanins have been carried out. Four anthocyanin pigments have been isolated apart from quercetin and lycopene. They are Cyanidin-3-O-(6′′-O-α-rhamnopyranosyl)-β-glucopyranoside (1), Cyanidin-3-O-(6′′-O-α-rhamnopyranosyl)-β-galactopyranoside (2), Cyanidin-3-O-β-glucopyranoside (3) and Cyanidin-O-β-galactopyranoside (4). These compounds were isolated by using HPLC and their structures were subsequently determined on the basis of spectroscopic analyses, i.e., ¹H NMR, ¹³C NMR, HMQC, HMBC, ESI-MS, FTIR, UV–Visible etc. The isolated compounds showed good antioxidant activity thus makes it suitable for use in food coloration and as a nutraceutical. Thus it is a promising pigment source for food applications.     

Hemiterpene glucosides and other constituents from Spiraea canescens

Five glycosides, 2-(trans-cinnamoyloxy-methyl)-1-butene-4-O-β-d-glucopyranoside (1), 4-(6′-O-trans-cinnamoyl)-(2-hydroxymethyl-4-hydroxy-butenyl-β-d-glucopyranoside (2), 6′′-O-trans-p-coumaroyl-(4-hydroxybenzoyl)-β-d-glucopyranoside (3), 6′-O-(4-methoxy-trans-cinnamoyl) α/β-d-glucopyranose (4) 6′-O-(4′′-methoxy-trans-cinnamoyl)-kaempferol-3-β-d-glucopyranoside (7) along with six known compounds, (+)-isolariciresinol 3a-O-β-d-glucopyranoside (8) (+)-lyoniresinol 3a-O-β-d-glucopyranoside (9), apigenin 7-O-β-d-glucopyranoside (10), quercetin 3-O-β-d-glucopyranoside (11), 6′-O-cinnamoyl-α/β-d-glucopyranose (6) 6’-O-p-coumaroyl-α/β-d-glucopyranose (5) were isolated from the whole plant of Spiraea canescens. Some of these compounds showed potent radical scavenging activity in relevant non-physiological assays. Their structures were determined by NMR spectroscopic and CID mass spectrometric techniques.     

Biosynthesis of Coumarin Glycosides by Transgenic Hairy Roots of Polygonum multiflorum

To investigate the substrate specificity and regio-selectivity of coumarin glycosyltransferases in transgenic hairy roots of Polygonum multiflorum, esculetin (1) and eight hydroxycoumarins (2–9) were employed as substrates. Nine corresponding glycosides (10–18) involving four new compounds, 6-chloro-4-methylcoumarin 7-O-β-D-glucopyranoside (15), 6-chloro-4-phenylcoumarin 7-O-β-D-glucopyranoside (16), 8-hydroxy-4-methylcoumarin 7-O-β-D-glucopyranoside (17), and 8-allyl-4-methylcoumarin 7-O-β-D-glucopyranoside (18), were biosynthesized by the hairy roots.