Punicafolin,an ellagitannin from the leaves of Punica granatum

A new ellagitannin, punicafolin has been isolated from the leaves of Punica granatum and characterized by physicochemical data and spectral evidence as 1,2,4-tri-O-galloyl-3,6-(R)-hexahydroxydiphenoyl-β-D-glucose. The occurrence in the leaves of the known tannins, granatins A and B, corilagin, strictinin, 1,2,4,6-tetra-O-galloyl-β-D-glucose and 1,2,3,4,6-penta-O-galloyl-β-D-glucose has also been demonstrated.     

Hydrolysable tannins and proanthocyanidins from green tea

Two hydrolysable tannins were isolated from green tea, and their structures were characterized by chemical and spectral means as 1,4,6-tri-O -galloyl-β-d-glucose and 1-O-galloyl-4,6-(?)-hexahydroxydiphenoyl-β-d-glucose. In addition, a new proanthocyanidin gallate was isolated, together with the known procyanidins B-2, B-4 and C-1. The structure of the proanthocyanidin was established as epigallocatechin-(4β → 8)-3-O-galloylepicatechin.     

Gallotannins of the freshwater green alga Spirogyra sp.

The green alga Spirogyra sp. accumulates tetra- through undecagalloylglucosyl gallotannins. The hexa- through undecagalloylglucoses are predominantly based on 1,2,3,4,6-penta-O-galloylglucose, whereas the major pentagalloylglucose is 3-O-digalloyl-1,2,6-tri-O-galloyl-β-D-glucose.     

Gemins D,E and F,ellagitannins from Geum japonicum

Three new ellagitannins, gemin D, E and F were isolated from the leaves of Geum japonicum. The structures of gemin D and F were established as 3-O-galloyl-4,6-O-[(S-hexahydroxydiphenoyl]-D-glucose and 6-O-caffeoyl-2,3-O-[(S-hexahydroxydiphenoyl]-D-glucose, respectively. Gemin E is a novel C-glucosidic ellagitanin having a dehydrohexahydroxydiphenoyl group in the molecule. Gemin D was also isolated from the flower buds of Camellia japonica.     

Hydrolysable tannins change physicochemical parameters of lipid nano-vesicles and reduce DPPH radical - Experimental studies and quantum chemical analysis

Tannins belong to plant secondary metabolites exhibiting a wide range of biological activity. One of the important aspects of the realization of the biological effects of tannins is the interaction with lipids of cell membranes. In this work we studied the interaction of two hydrolysable tannins: 1,2,3,4,6-penta-O-galloyl-β-d-glucose (PGG) and 1,2-di-O-galloyl-4,6-valoneoyl-β-d-glucose (T1) which had the same number of both aromatic rings (5) and hydroxyl groups (15) but differing in flexibility due to the presence of valoneoyl group in the T1 molecule with DMPC (dimyristoylphosphatidylcholine) lipid nano-vesicles (liposomes). Tannins-liposomes interactions were investigated using fluorescence spectroscopy, differential scanning calorimetry, laser Doppler velocimetry, dynamic light scattering and Fourier Transform Infra-Red spectroscopy. It was shown that more flexible PGG molecules stronger decreased the microviscosity of the liposomal membranes and increased the values of negative zeta potential in comparison with the more rigid T1. Both compounds diminished the phase transition temperature of DMPC membranes, interacted with liposomes via PO groups of head of phospholipids and their hydrophobic regions. These tannins neutralized DPPH free radicals with the stoichiometry of the reaction equal 1:1.The effects of the studied compounds on liposomes were discussed in relation to tannin quantum chemical parameters calculated by molecular modeling.     

Action of tannin on cellular membranes: Novel insights from concerted studies on lipid bilayers and native cells

Hydrolyzable tannin (3,6-bis-O-digalloyl-1,2,4-tri-O-galloyl-β-d-glucose) has a dual effect on the cell membrane: (1) it binds to a plasmalemmal protein of the Chara corallina cell (C₅₀ = 2.7 ± 0.3 μM) and (2) it forms ionic channels in the lipid membrane. Based on these facts, a molecular model for the interaction of tannins with the cell membrane is proposed. The model suggests that the molecules of hydrolyzable tannin bind electrostatically to the outer groups of the membrane protein responsible for the Ca²⁺-dependent chloride current and blocks it. Some tannin molecules penetrate into the hydrophobic region of the membrane, and when a particular concentration is reached, they form ion-conducting structures selective toward Cl^?.     

Pendulaosides A and B. Two acylated triterpenoid saponins from Harpullia pendula seed extract

Two new acylated triterpenoid saponins named pendulaosides A and B as well as the known phenolic compounds methyl gallate, gallic acid, 1,2,3,6-tera-O-galloyl-β-d-glucose and 1,2,3,4,6-penta-O-galloyl-β-d-glucose, were isolated from the seeds of Harpullia pendula. The structures of pendulaosides A and B were determined using extensive 1D and 2D NMR analysis and mass spectrometry as well as acid hydrolysis, as 3-O-β-d-glucopyranosyl-(1→2)-[α-L-arabinofuranosyl-(1→3)]-β-d-glucuronopyranosyl-22-O-angeloyl-3β,16α,22α,24β,28-pentahydroxylolean-12-ene and 3-O-β-d-glucopyranosyl-(1→2)-[α-L-arabinofuranosyl-(1→3)]-β-d-glucuronopyranosyl-16-O-(2-methylbutyroyl)-3β,16α,22α,24β,28-pentahydroxylolean-12-ene, respectively. To the best of our knowledge the two triterpene parts 22-O-angeloyl-3β,16α,22α,24β,28-pentahydroxylolean-12-ene and16-O-(2-methylbutyroyl)-3β,16α,22α,24β,28-pentahydroxylolean-12-ene have never been characterized before. The two isolated saponins were assayed for their in-vitro cytotoxic activity against the three human tumor cell lines HepG2, MCF7 and PC3. The results showed that pendulaoside A exhibited moderate activity on PC3 cell line with IC50value equal to 13.0 μM and weak activity on HepG2 cell line with IC50 value equal to 41.0 μM. Pendulaoside B proved to be inactive against the three used cell lines.     

Syntheses of 2-acetamido-2-deoxy-4-O-βD-galacto-pyranosyl-D-mannose and -D-glucose and of 2-acetamido-2-deoxy-4-O-βD-mannopyranosyl-D-mannose and -D-glucose

2-acetamido-2-deoxy-4-O-β-D-galactopyranosyl-D-mannose (6) and -D-glucose (7) were prepared by addition of nitromethane to 3-O-β-D-galactopyranosyl-D-arabinose, followed by acetylation, ammonolysis, and application of the Nef reaction. Similarly, 2-acetamido-2-deoxy-4-O-β-D-mannopyranosyl-D-mannose (14) and -D-glucose (15) were prepared by the same scheme from 3-O-β-D-mannopyranosyl-D-arabinose. In the two series of experiments, 6 and 14 were the respective major products. Epimerization of the 2-acetamido-2-deoxy-D-mannose residue in 6 and 14 yielded 7 and 15, respectively.     

Oxazoline synthesis of 1,2-trans-2-acetamido-2-deoxyglycosides. Glycosylation with 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-D-galactopyrano)-[2′,1′:4,5]-2-oxazoline

The glycosylating activity of 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-D-galactopyrano)-[2′,1′:4,5]-2-oxazoline has been tested in reaction with partially protected saccharides having free primary or secondary hydroxyl groups or with hydroxy amino acids. 3-O-(2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-D-galactopyranosyl)-N-benzyloxycarbonyl-L-serine benzyl ester (3), 6-O-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-D-galactopyranose (5), p-nitrophenyl 2-acetamido-6-O-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-2-deoxy-β-D-glucopyranoside (7), 6-O-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-D-glucose (9), and 3-O-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-D-glucose (11) were synthesized in high yield.     

Synthèse du 4-O-[(s)-1-carboxyéthyl]-d-glucose et de son isomère (R)

Alkylation of benzyl 2,3,6-tri-O-benzyl-β-D-glucopyranoside in N,Ndimethyl formamide with (R)-2-chloropropionic acid gave crystalline benzyl 2,3,6-tri-O-benzyl-4-O-[(S)-carboxyethyl]-β-D-glucopyranoside. After hydrogenolysis of the benzyl group 4-O-[(S)-D-carboxyethyl]-D-glucose was obtained which lactonized very easily. Treatment of benzyl 2,3,6-tri-O-benzyl-4-O-[(S)-1-carboxyethyl]-β-D-glucopyranoside with diazomethane gave cristalline benzyl 2,3,6-tri-O-benzyl-4-O-[(S)-1-(methoxycarbonyl)ethyl]-β-D-glucopyranoside, which was reduced with lithium aluminium hydride to crystalline benzyl 2,3,6-tri-O-benzyl-4-O-[(S)-1-(hydroxymethyl)ethyl]-β-D-glucopyranoside After hydrogenolysis of the benzyl groups 4-O-[(S)-1-(hydroxymethyl)ethyl]-D-glucose was obtained. A similar sequence of reactions was performed with (S)-2-chloropropionic acid.     

Scyllo-quercitol gallates and hexahydroxydiphenoates from quercus stenophylla

A series of gallotannins and ellagitannins based on a scyllo-quercitol core have been isolated from the bark of Quercus stenophylla. On the basis of chemical and spectroscopic evidence, the structures of the gallotannins have been established as 2-O-, 1,2-di-O-, 1,2,3-tri-O-, 1,2,3,4-tetra-O- and 1,2,3,4,5-penta-O-galloyl-scyllo-quercitols, and the ellagitannins as 1,5-di-O-galloyl-2,3-(S)-hexahydroxydiphenoyl-scyllo-quercitol and 1,4-(or 4,5)-di-O-galloyl-2,3-(S)-hexahydroxydiphenoyl-     

Hydrolyzable tannins of tamaricaceous plants. IV: Micropropagation and ellagitannin production in shoot cultures of Tamarix tetrandra

Shoot cultures of Tamarix tetrandra on Linsmaier–Skoog (LS) agar medium with 30 g l⁻¹ sucrose, 2.13 mg l⁻¹ indoleacetic acid and 2.25 mg l⁻¹ benzyl adenine produced ellagitannins found in intact plants of the Tamaricaceae. This was demonstrated by the isolation of 14 monomeric–tetrameric ellagitannins from the aq. Me₂CO extract of the cultured tissues. This is the first report on the production of ellagitannin tetramers by plant tissue culture. The effects of light and certain medium constituents on tissue growth and ellagitannin production were examined. The contents of representative tannins of different types [i.e., tellimagrandin II (monomer), hirtellin A (linear GOG-type dimer), hirtellin B (hellinoyl-type dimer), hirtellin C (macrocyclic-type dimer), and hirtellin T1 (linear GOG-type trimer)] in the resultant tissues in response to these factors were estimated by HPLC, and the optimal condition for production of these tannins were established. Shoots cultured on LS hormone-free medium promoted root development, and regenerated plants could adapt to ordinary soil and climate. Acclimatized and intact T. tetrandra plants that were collected in November and May, respectively, demonstrated seasonal differences in individual ellagitannin contents. HPLC comparison of individual ellagitannin contents in different plant materials (i.e., leaves, stems, and roots) of intact T. tetrandra plants is also reported. The results are discussed with respect to cellular deposition and biosynthetic relationship of tannins.     

Glycosylation of 2-phenylpropionic acid and its ethyl ester in suspension cultures of Nicotiana tabacum,Dioscoreophyllum cumminsii and Aconitum japonicum

Suspension cultures of Nicotiana tabacum and Dioscoreophyllum cumminsii converted 2-(RS)-phenylpropionic acid and its ethyl ester into 2-(RS)-phenylpropionyl β-D-glucopyranoside, 2-(RS)-phenylpropionyl 6-O-β-D-glucopyranosyl-β-D-glucopyranoside and 6-O-β-D- glucopyranosyl-2-O-[2-(RS)-phenylpropionyl]-D-glucose which accumulated in the cells. A suspension culture of Aconitum japonicum converted these substrates into ethyl 6-O-[2-(RS)-phenylpropionyl]- β-D-glucopyranoside which was mostly excreted into the medium. The diastereomeric mixture of the glucosyl esters of 2-(RS)-phenylpropionic acid was resolved by HPLC to show the ratio of R:S was 1:1.     

Sclerophylly in Qualea Parviflora (Vochysiaceae): Influence of Herbivory, Mineral Nutrients, and Water Status

Qualea parviflora Mart. (Vochysiaceae) is a deciduous tree, commonly observed in campo sujo, cerrado sensu stricto and cerradão vegetation types in Brazilian cerrado (savannas). In this study we investigated herbivory, nutritional, and water status effects on leaf sclerophylly of Q. parviflora. Twenty fully expanded leaves were taken from 10 plants in each vegetation type four times a year. Mean leaf concentration of N, P, K, Ca, C, Al, Si, and percentage of total phenols, herbivory and tannins were measured on a plant basis. Leaf specific mass (LSM) (g m^?2), a sclerophylly index, and pre-dawn leaf water potential (MPa) were also recorded. Soil samples below each tree were collected to quantify N–NO₃, N–NH₄, P, K, Mn, soil moisture, organic matter, Si, and Al. Qualea parviflora showed a LSM from 69 to 202 g m^?2 and leaves were younger and less sclerophyllous in November (beginning of rainy season). Q. parviflora inhabiting the cerradão had leaves with higher concentration of nutrients and lower sclerophylly while trees in campo sujo and cerrado sensu stricto did not show significant differences in leaf sclerophylly. The concentrations of N, P, K and tannins had an inverse relationship with leaf age. Concentration of phenols, Al, C, Ca, Si, C/N and Ca/K increased with leaf age. The concentrations of P and Ca/K ratio in leaves explained 60% of variation observed in leaf sclerophylly. We did not find any significant relationship between the level of sclerophylly and water potential or herbivory. Our results corroborate the hypothesis that predicts lower concentrations of essential macronutrients would be the main factors influencing higher sclerophylly in leaves of Q. parviflora plants in Cerrado.     

Distribution of metabolites in galled and non-galled foliar tissues of Tibouchina pulchra

This paper reports the contents of foliar metabolites of Tibouchina pulchra (Melastomataceae) in (a) galls induced by a lepidopteran, (b) remaining parts of the galled leaf after gall removal, (c) leaves opposite to the galled leaf, and (d) leaves of non-infested stem branches (control). The parameters assayed were soluble phenols, flavonoids, tannins, lignins, fibers, soluble carbohydrates, lipids and organic nitrogen. Differences in the parameters assayed were evaluated using Principle Components Analysis. Compared to other tissues, galls showed significantly higher contents of soluble phenols, tannins, lignins, fibers, soluble carbohydrates and lipids, and significantly lower contents of flavonoids and organic nitrogen. Apart from gall tissues, in most cases no significant differences were detected in the quantitative analyses among the leaf tissues assayed. Flavonols and flavones were not detected in galls. Other tissues revealed a similar flavonoid pattern, characterized by 3-O-monoglycosides of kaempferol, myricetin and quercetin. A luteolin glycoside was obtained exclusively from control leaves. Carbohydrate amounts are lower in the foliar tissues closer to the galls than in non-galled tissues. Palmitic acid was essentially the sole fatty acid found in all tissues analysed. The high lipid content of the galls suggests that such substances represent the main energy source for the insect, and suggests that the studied galls could be classified as cynipid galls. The observed metabolic changes taking place in the galls strengthen the hypotheses that galls behave as new organs, operating a metabolic machinery of their own.     

Chromone acyl glucosides and an ayanin glucoside from Dasiphora parvifolia

Two new chromone acyl glucosides, 5-hydroxy-7-O-(6-O-p-cis-coumaroyl-β-D-glucopyranosyl)-chromone (1) and 5-hydroxy-7-O-(6-O-p-trans-coumaroyl-β-D-glucopyranosyl)-chromone (2), and a new flavonoid glucoside, ayanin 3′-O-β-D-glucopyranoside (3) were isolated from aerial parts of Dasiphora parvifolia, together with flavonoid glycosides (4–10), catechins (11, 12), and hydrolysable tannins (13, 14). The chemical structures of these compounds were elucidated on the basis of spectroscopic data. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and the hyaluronidase inhibitory activity of these compounds were evaluated.     

Tellimagrandin I,HCV invasion inhibitor from Rosae Rugosae Flos

By use of the model virus, expressing the HCV envelope proteins E1 and E2, bioassay guided separation of the MeOH extract from Rosa rugosa Thunb. disclosed tellimagrandin I (1) together with eugeniin (2) and casuarictin (3) as the potent HCV invasion inhibitors. Furthermore, structure–activity relationship analysis of some relative tannins including the synthesized analogs elucidated the partial structures crucial for potent activity of 1.     

Analysis of sugar derivatives by chemical-ionization mass-spectrometry

D-Glucose diethyl dithioacetal (1), its penta-O-acetyl derivative (2), penta-O-acetyl-aldehydo-D-glucose (3), L-xylo-hexulose phenylosotriazole (4), 1,2:5,6-di-O-isopropylidene-D-mannitol (5), 1,2:4,5-di-O-isopropylidene-β-D-fructopyranose (6), 1,2-O-isopropylidene-α-D-glucofuranose (7) and its triacetate (8), 1,6-anhydro-β-D-galactopyranose (9) and its triacetate (10), D-glucopyranose (11), methyl β-D-glucopyranoside tetraacetate (12), 1-thio-β-D-glucopyranose pentaacetate (13), β-D-fructofuranose pentaacetate (14), and raffinose hendecaacetate (15) have been examined by chemical-ionization mass-spectrometry with both isobutane and ammonia as ionizing intermediates. Extreme simplicity characterizes these spectra, and, in most instances, molecular-weight data are available from intact, protonor NH₄⁺capture ions; the limited fragmentation that occurs corresponds in large measure to simple dehydration or substituent-cleavage processes, and is strongly dependent upon the groups present, so that considerable information about the substituent groups in the sugar molecule may be inferred.     

Effects of artificial grassland establishment on soil nutrients and carbon properties in a black-soil-type degraded grassland

Despite a growing knowledge of nutrient limitation for mangrove species and how mangroves adapt to low nutrients, there is scant information about the relative importance of N:P ratio and leaf phenolics variability in determining nutrient conservation. In this study, we evaluated possible nutrient conservation strategies of a mangrove Rhizophora stylosa under nutrient limitation. 1. The leaf nutrient concentrations of R. stylosa changed with season, with the highest N concentration in winter and the highest P concentration in spring for both mature and senescent leaves. Leaf N and P concentrations decreased significantly during leaf senescence. Based on N:P ratios R. stylosa forest was N-limited. Accordingly, the nitrogen resorption efficiency (NRE) was significantly higher than phosphorus resorption efficiency (PRE) for the R. stylosa leaves during leaf senescence. The NRE and PRE both reached the highest in the autumn. Average N and P concentrations in the senescent leaves were 0.15% and 0.06% for R. stylosa, respectively, indicating a complete resorption of N and an incomplete resorption of P. There was a significant negative correlation between nitrogen resorption proficiency (NRP) and NRE, meanwhile phosphorus resorption proficiency (PRP) and PRE correlation was also highly significantly. 2. R. stylosa leaves contained relatively high tannin level. Total phenolics, extractable condensed tannins and total condensed tannins contents increased during leaf senescence, and changed between seasons. The lowest concentrations of total phenolics, extractable condensed tannins and total condensed tannins occurred in summer, total phenolics concentrations were inversely related to nitrogen or phosphorus concentrations. 3. Our results confirmed that resorption efficiency during leaf senescence depends on the type of nutrient limitation, and NRE was much higher than PRE under N-limited conditions. R. stylosa forest developed several nutrient conservation strategies in the intertidal coastline surroundings, including high nitrogen resorption efficiency, low nutrient losses and high tannins level.     

Leaf litter quality affects aquatic insect emergence: contrasting patterns from two foundation trees

Reciprocal subsidies between rivers and terrestrial habitats are common where terrestrial leaf litter provides energy to aquatic invertebrates while emerging aquatic insects provide energy to terrestrial predators (e.g., birds, lizards, spiders). We examined how aquatic insect emergence changed seasonally with litter from two foundation riparian trees, whose litter often dominates riparian streams of the southwestern United States: Fremont (Populus fremontii) and narrowleaf (Populus angustifolia) cottonwood. P. fremontii litter is fast-decomposing and lower in defensive phytochemicals (i.e., condensed tannins, lignin) relative to P. angustifolia. We experimentally manipulated leaf litter from these two species by placing them in leaf enclosures with emergence traps attached in order to determine how leaf type influenced insect emergence. Contrary to our initial predictions, we found that packs with slow-decomposing leaves tended to support more emergent insects relative to packs with fast-decomposing leaves. Three findings emerged. Firstly, abundance (number of emerging insects m^?2 day^?1) was 25 % higher on narrowleaf compared to Fremont leaves for the spring but did not differ in the fall, demonstrating that leaf quality from two dominant trees of the same genus yielded different emergence patterns and that these patterns changed seasonally. Secondly, functional feeding groups of emerging insects differed between treatments and seasons. Specifically, in the spring collector-gatherer abundance and biomass were higher on narrowleaf leaves, whereas collector-filterer abundance and biomass were higher on Fremont leaves. Shredder abundance and biomass were higher on narrowleaf leaves in the fall. Thirdly, diversity (Shannon’s H′) was higher on Fremont leaves in the spring, but no differences were found in the fall, showing that fast-decomposing leaves can support a more diverse, complex emergent insect assemblage during certain times of the year. Collectively, these results challenge the notion that leaf quality is a simple function of decomposition, suggesting instead that aquatic insects benefit differentially from different leaf types, such that some use slow-decomposing litter for habitat and its temporal longevity and others utilize fast-decomposing litter with more immediate nutrient release.