Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Giovanni Pacioni , Cinzia Rapino , Osvaldo Zarivi , Anastasia Falconi , Marco Leonardi , Natalia Battista , Sabrina Colafarina , Manuel Sergi , Antonella Bonfigli , Michele Miranda , Daniela Barsacchi , Mauro Maccarrone Truffles are the fruiting body of fungi, members of the Ascomycota phylum endowed with major gastronomic and commercial value. The development and maturation of their reproductive structure are dependent on melanin synthesis. Since anandamide, a prominent member of the endocannabinoid system (ECS), is responsible for melanin synthesis in normal human epidermal melanocytes, we thought that ECS might be present also in truffles. Here, we show the expression, at the transcriptional and translational levels, of most ECS components in the black truffle Tuber melanosporum Vittad. at maturation stage VI. Indeed, by means of molecular biology and immunochemical techniques, we found that truffles contain the major metabolic enzymes of the ECS, while they do not express the most relevant endocannabinoid-binding receptors. In addition, we measured anandamide content in truffles, at different maturation stages (from III to VI), through liquid chromatography–mass spectrometric analysis, whereas the other relevant endocannabinoid 2-arachidonoylglycerol was below the detection limit.Overall, our unprecedented results suggest that anandamide and ECS metabolic enzymes have evolved earlier than endocannabinoid-binding receptors, and that anandamide might be an ancient attractant to truffle eaters, that are well-equipped with endocannabinoid-binding receptors.
Publication date: January 2015 Source:Phytochemistry, Volume 109 Author(s): Jian-Hong Yang , Jian-Xin Pu , Jin Wen , Xiao-Nian Li , Fei He , Jia Su , Yan Li , Han-Dong Sun Five 3,4-seco-cycloartane triterpenoids were isolated from the stems of Kadsura ananosma, two of which had rearranged 5/6 consecutive carbocycle rings C/D (trivially named ananosins A (1) and B (2)), one had a migrated CH3-18 (named ananosins C (3)), and two were analogs, ananosins D (4) and E (5). Their structures were characterized by comprehensive spectroscopic analysis, especially using 2D NMR spectra. A biogenetic pathway to 1 was proposed. These 5 compounds, together with 5 known analogs isolated from the same origin, were evaluated for their cytotoxicity against HL-60, SMMC-7721, A-549, PANC-1, and SK-BR-3 human cancer cells, but were inactive.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Milka Todorova , Antoaneta Trendafilova , Kalina Danova , Luke Simmons , Evelyn Wolfram , Beat Meier , Rainer Riedl , Luba Evstatieva Ten new sesquiterpene alcohols of which seven germacranes, a eudesmane, a guaiane and an oplopane were isolated from the aerial parts of Artemisia alba Turra. Their structures and relative stereochemistry were elucidated by spectral methods (1H and 13C NMR, COSY, HSQC, HMBC, NOESY, and MS). In addition, the known 7-hydroxycadin-4-en-3-one, centaureidin and axillarin were found for the first time in the studied species.
Publication date: Available online 4 February 2015 Source:Phytochemistry Author(s): Marian D. Quain , Matome E. Makgopa , James W. Cooper , Karl J. Kunert , Christine H. Foyer Cysteine proteases and cystatins have many functions that remain poorly characterised, particularly in crop plants. We therefore investigated the responses of these proteins to nitrogen deficiency in wild-type soybeans and in two independent transgenic soybean lines (OCI-1 and OCI-2) that express the rice cystatin, oryzacystatin-I (OCI). Plants were grown for four weeks under either a high (5mM) nitrate (HN) regime or in the absence of added nitrate (LN) in the absence or presence of symbiotic rhizobial bacteria. Under the LN regime all lines showed similar classic symptoms of nitrogen deficiency including lower shoot biomass and leaf chlorophyll. However, the LN-induced decreases in leaf protein and increases in root protein tended to be smaller in the OCI-1 and OCI-2 lines than in the wild type. When LN-plants were grown with rhizobia, OCI-1 and OCI-2 roots had significantly more crown nodules than wild-type plants. The growth nitrogen regime had a significant effect on the abundance of transcripts encoding vacuolar processing enzymes (VPEs), LN-dependent increases in VPE2 and VPE3 transcripts in all lines. However, the LN-dependent increases of VPE2 and VPE3 transcripts were significantly lower in the leaves of OCI-1 and OCI-2 plants than in the wild type. These results show that nitrogen availability regulates the leaf and root cysteine protease, VPE and cystatin transcript profiles in a manner that is in some cases influenced by ectopic OCI expression. Moreover, the OCI-dependent inhibition of papain-like cysteine proteases favours increased nodulation and enhanced tolerance to nitrogen limitation, as shown by the smaller LN-dependent decreases in leaf protein observed in the OCI-1 and OCI-2 plants relative to the wild type.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Carina N. Casero , Juan C. Oberti , Clara I. Orozco , Alejandro Cárdenas , Iván Brito , Gloria E. Barboza , Viviana E. Nicotra Nine withanolides were isolated from the aerial parts of Deprea bitteriana, Depreacuyacensis, and Depreazamorae. D.bitteriana yielded two withaphysalins, D. cuyacensis gave two 13,14-seco withaphysalins, while D. zamorae yielded five physangulidines. The compounds were fully characterized by a combination of spectroscopic methods (1D and 2D NMR and MS). All compounds isolated from D.bitteriana and D. cuyacensis were obtained as epimeric mixtures at C-18. The structure of physangulidine D was confirmed by X-ray diffraction analysis. The skeletons found in this research support the chemotaxonomical position of the genus Deprea in the tribe Physalideae.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Angela Bisio , Anna Maria Schito , Samad Nejad Ebrahimi , Matthias Hamburger , Giacomo Mele , Gabriella Piatti , Giovanni Romussi , Fabrizio Dal Piaz , Nunziatina De Tommasi From the aerial parts of Salvia adenophora Fernald four derivatives of 12-oxo-phytodienoic acid (1–4) together with five clerodane diterpenoids (5, 6, 8–10), and one known diterpene (7) have been isolated. Compounds 1–6 and 8–10 are described for the first time. The structures were established by extensive 1D, 2D NMR and HRESI-TOFMS spectroscopic methods. Finally, the absolute configuration has been established by comparing of experimental and quantum chemical calculation of ECD spectra. Despite a total lack of antimicrobial activity of the plant extract, hinting to the existence of antagonistic interactions in the crude material, three oxylipins (2–4) displayed a promising inhibition on Gram-positive multidrug-resistant clinical strains including Staphylococcus aureus, Streptococcus agalactiae and, particularly, Staphylococcus epidermidis, while the compounds 9 and 10 revealed a specific and strain-dependent activity against S. epidermidis. Interestingly, the inhibition provided by these compounds was independent of the resistance patterns of these pathogens to classic antibiotics. No action was reported on Gram-negative strains nor on Candida albicans. These results confirm that clerodanes and, particularly, prostaglandin-like compounds can be considered as interesting antimicrobial agents deserving further study.
Publication date: Available online 3 February 2015 Source:Phytochemistry Author(s): Stefania Paparella , Aldo Tava , Pinarosa Avato , Elisa Biazzi , Anca Macovei , Marco Biggiogera , Daniela Carbonera , Alma Balestrazzi In the present work, eleven saponins and three sapogenins purified from Medicago sativa were tested for their cytotoxicity against highly proliferating white poplar (Populus alba L.) cell suspension cultures. After preliminary screening, four saponins with different structural features in terms of aglycone moieties and sugar chains (saponin 3, a bidesmoside of hederagenin; saponins 4 and 5, monodesmoside and bidesmoside of medicagenic acid respectively, and saponin 10, a bidesmoside of zanhic acid) and different cytotoxicity were selected and used for further investigation on their structure–activity relationship. Transmission Electron Microscopy (TEM) analyses provided for the first time evidence of the effects exerted by saponins on plant cell wall integrity. Exposure to saponin 3 and saponin 10 resulted into disorganization of the outer wall layer and the effect was even more pronounced in white poplar cells treated with the two medicagenic acid derivatives, saponins 4 and 5. Oxidative burst and nitric oxide accumulation were common hallmarks of the response of white poplar cells to saponins. When DNA damage accumulation and DNA repair profiles were evaluated by Single Cell Gel Electrophoresis, induction of single and double strand breaks followed by effective repair was observed within 24h. The reported data are discussed in view of the current issues dealing with saponin structure–activity relationship.
Biological effects of Medicago sativa purified saponins were tested on proliferating white poplar cell suspension cultures. TEM analysis along with cytotoxicity and genotoxicity assays were performed.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Sinem Aslan Erdem , Anne-Claire Mitaine-Offer , Tomofumi Miyamoto , Murat Kartal , Marie-Aleth Lacaille-Dubois Four new oleanane-type saponins 3-O-?-l-rhamnopyranosyl-(1?4)-?-d-glucuronopyranosyl-22-O-?,?-dimethylacryloylA1-barrigenol (1), 3-O-?-l-rhamnopyranosyl-(1?4)-?-d-glucuronopyranosyl-22-O-angeloylA1-barrigenol (2), 3-O-?-d-glucopyranosyl-(1?2)-[?-d-glucopyranosyl-(1?6)]-?-d-glucopyranosyl-21,22,28-O-triacetyl-(3?,21?,22?)-olean-12-en-16-one (3), and 3-O-?-d-glucopyranosyl-(1?2)-glucopyranosyl-22-O-?-d-glucopyranosylsteganogenin (4), along with the known 3-O-?-d-galactopyranosyl-(1?2)-[?-l-arabinopyranosyl-(1?3)]-?-d-glucuronopyranosyl-22-O-angeloylA1-barrigenol and 3-O-?-l-rhamnopyranosyl-(1?4)-?-d-glucuronopyranosyloleanolic acid, were isolated from a methanol extract of the roots of Eryngium kotschyi by multiple chromatographic steps. Saponins 3 and 4 are unusual by the original structure of their aglycon. Compound 3 possessed an oleanane-type skeleton with a 21,22,28-triacetylation and a ketone function at the C-16 position. For compound 4, the 17,22-seco-oleanolic acid skeleton is rarely found in natural saponins.
Publication date: Available online 24 January 2015 Source:Phytochemistry Author(s): Jessie Moniodis , Christopher G. Jones , E. Liz Barbour , Julie A. Plummer , Emilio L. Ghisalberti , Joerg Bohlmann The fragrant heartwood oil of West Australian sandalwood (Santalum spicatum) contains a mixture of sesquiterpene olefins and alcohols, including variable levels of the valuable sesquiterpene alcohols, ?- and ?-santalol, and often high levels of E,E-farnesol. Transcriptome analysis revealed sequences for a nearly complete set of genes of the sesquiterpenoid biosynthetic pathway in this commercially valuable sandalwood species. Transcriptome sequences were produced from heartwood xylem tissue of a farnesol-rich individual tree. From the assembly of 12,537 contigs, seven different terpene synthases (TPSs), several cytochromes P450, and allylic phosphatases were identified, as well as transcripts of the mevalonic acid and methylerythritol phosphate pathways. Five of the S. spicatum TPS sequences were previously unknown. The full-length cDNA of SspiTPS4 was cloned and the enzyme functionally characterized as a multi-product sesquisabinene B synthase, which complements previous characterization of santalene and bisabolol synthases in S. spicatum. While SspiTPS4 and previously cloned sandalwood TPSs do not explain the prevalence of E,E-farnesol in S. spicatum, the genes identified in this and previous work can form a basis for future studies on natural variation of sandalwood terpenoid oil profiles.
Santalum spicatum heartwood xylem produces fragrant sesquiterpenoids. Sequences of sesquiterpenoid biosynthesis including terpene synthase and cytochrome P450 sequences were identified in a xylem transcriptome.
Publication date: Available online 13 January 2015 Source:Phytochemistry Author(s): Hideto Nakamura , Ken Sawada , Hiroya Araie , Iwane Suzuki , Yoshihiro Shiraiwa The hydrocarbons in cultures of marine haptophytes Emiliania huxleyi NIES837 and Gephyrocapsa oceanica NIES1315 were analyzed, and nonacosadienes and hentriacontadienes were detected as the major compounds in both strains. C29 and C31 monoenes and di-, tri- and tetra-unsaturated C33 alkenes were also detected as minor compounds but not C37 and C38 alkenes. The positions of the double bonds in the C29 and C31 alkenes were determined by mass spectrometry of their dimethyl disulfide (DMDS) adducts. Among the four C29 alkenes identified, the most abundant isomer was 2,20-nonacosadiene, and the other three compounds were 1,20-nonacosadiene, 3,20-nonacosadiene and 9-nonacosene, respectively. Hitherto, 2,20-nonacosadiene and 3,20-nonacosadiene were unknown to be natural products. The double bond at the n-9 (?9) position in these C29 alkenes is hypothesized to be derived from precursors of unsaturated fatty acids possessing an n-9 double bond, such as (9Z)-9-octadecenoic acid. Nonacosadienes have the potential for being used as distinct haptophyte biomarkers.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Marisa Freitas , Alexandre Campos , Joana Azevedo , Aldo Barreiro , Sébastien Planchon , Jenny Renaut , Vitor Vasconcelos The intensification of agricultural productivity is an important challenge worldwide. However, environmental stressors can provide challenges to this intensification. The progressive occurrence of the cyanotoxins cylindrospermopsin (CYN) and microcystin-LR (MC-LR) as a potential consequence of eutrophication and climate change is of increasing concern in the agricultural sector because it has been reported that these cyanotoxins exert harmful effects in crop plants. A proteomic-based approach has been shown to be a suitable tool for the detection and identification of the primary responses of organisms exposed to cyanotoxins. The aim of this study was to compare the leaf-proteome profiles of lettuce plants exposed to environmentally relevant concentrations of CYN and a MC-LR/CYN mixture. Lettuce plants were exposed to 1, 10, and 100?g/l CYN and a MC-LR/CYN mixture for five days. The proteins of lettuce leaves were separated by two-dimensional electrophoresis (2-DE), and those that were differentially abundant were then identified by matrix-assisted laser desorption/ionization time of flight-mass spectrometry (MALDI-TOF/TOF MS). The biological functions of the proteins that were most represented in both experiments were photosynthesis and carbon metabolism and stress/defense response. Proteins involved in protein synthesis and signal transduction were also highly observed in the MC-LR/CYN experiment. Although distinct protein abundance patterns were observed in both experiments, the effects appear to be concentration-dependent, and the effects of the mixture were clearly stronger than those of CYN alone. The obtained results highlight the putative tolerance of lettuce to CYN at concentrations up to 100?g/l. Furthermore, the combination of CYN with MC-LR at low concentrations (1?g/l) stimulated a significant increase in the fresh weight (fr. wt) of lettuce leaves and at the proteomic level resulted in the increase in abundance of a high number of proteins. In contrast, many proteins exhibited a decrease in abundance or were absent in the gels of the simultaneous exposure to 10 and 100?g/l MC-LR/CYN. In the latter, also a significant decrease in the fr. wt of lettuce leaves was obtained. These findings provide important insights into the molecular mechanisms of the lettuce response to CYN and MC-LR/CYN and may contribute to the identification of potential protein markers of exposure and proteins that may confer tolerance to CYN and MC-LR/CYN. Furthermore, because lettuce is an important crop worldwide, this study may improve our understanding of the potential impact of these cyanotoxins on its quality traits (e.g., presence of allergenic proteins).
Publication date: Available online 10 January 2015 Source:Phytochemistry Author(s): Lívia S. de Medeiros , Lucas M. Abreu , Anita Nielsen , Hanne Ingmer , Thomas O. Larsen , Kristian F. Nielsen , Edson Rodrigues-Filho Dereplication methodology using UHPLC–DAD–QTOFMS was applied during the metabolic profiling investigation of the endophyte Setophoma sp., a fungus isolated from symptomless guava fruits. The approach performed allowed a fast analysis of the microbial secondary metabolites. From this fungus, seven highly C-alkylated depsides were isolated and identified as polyketides thielavins S, T, U and V and lecanorins D, E and F. Their structures were elucidated through spectroscopic methods including NMR, HRMS and especially with assistance of HRMS/MS experiments. The compounds were tested for quorum sensing regulation activity in the virulence gene expression of Staphylococcus aureus, but no inhibitory effect was detected. Nevertheless, moderate antibacterial activity was encountered in three of tested depsides, particularly with thielavin T, whose MIC was 6.25?g/mL against S. aureus.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Berenice Ovalle-Magallanes , Omar N. Medina-Campos , José Pedraza-Chaverri , Rachel Mata An aqueous extract from the seeds of Swietenia humilis (31.6–100mg/kg bw) lowered (p<0.05) blood glucose levels in normal and nicotinamide–streptozotocin (NA–STZ)-induced hyperglycemic mice. Furthermore, when administered to fructose-fed rats with metabolic syndrome, the decoction showed significant antihyperglycemic, hypoglycemic and hypolipidemic effects, as well as an augmentation of hepatic glycogen. Limonoids 2-hydroxy-destigloyl-6-deoxyswietenine acetate (1), humulin B (2), methyl-2-hydroxy-3-?-isobutyroxy-1-oxomeliac-8(30)-enate (3), methyl-2-hydroxy-3-?-tigloyloxy-1-oxomeliac-8(30)-enate (4), humilinolide G (5), humilinolide C (6), methyl-2-hydroxy-3-?-isobutyoyl-8?,30?-epoxy-1-oxo-meliacate (7), and humilinolide H (8), were isolated from a CH2Cl2–MeOH (1:1) extract of the seeds. Compounds 5 and 8 are analogs of compounds 6 and 7. The structure of 5 was unequivocally established by X-ray analysis. When tested in normal and NA–STZ-hyperglycemic mice, compounds 1, 2, and 4 (3.16–31.6mg/kg bw) decreased glycemia during an oral glucose tolerance test. The present investigation sustains the contemporary popular uses of S. humilis seeds for treating metabolic disorders, including diabetes and dyslipidemia and demonstrates the potential of the mexicanolides as antihyperglycemic agents.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Shuang-Shuang Zhang , Qing-Yun Ma , Sheng-Zhuo Huang , Hao-Fu Dai , Zhi-Kai Guo , Zhi-Fang Yu , You-Xing Zhao Nine lanostanoids, together with nine known ones, were isolated from the ethyl acetate extract of the fruiting bodies of the mushroom Haddowia longipes. Their structures were elucidated as 11-oxo-ganoderiol D, lanosta-8-en-7,11-dioxo-3?-acetyloxy-24,25,26-trihydroxy, lanosta-8-en-7-oxo-3?-acetyloxy-11?,24,25,26-tetrahydroxy, lanosta-7,9(11)-dien-3?-acetyloxy-24,25,26-trihydroxy, lanosta-7,9(11)-dien-3?-acetyloxy-24,26-dihydroxy-25-methoxy, 11-oxo-lucidadiol, 11?-hydroxy-lucidadiol, lucidone H and lanosta-7,9(11),24E-trien-3?-acetyloxy-26,27-dihydroxy by analysing their 1D/2D NMR and MS spectra. In addition, bioassays of inhibitory activity against acetylcholinesterase (AChE) of all compounds showed that thirteen compounds possessed inhibitory activity against AChE with the percentage inhibition ranging from 10.3% to 42.1% when tested at 100?M.
Nine lanostanoids (1–9) together with nine known ones were isolated from fungus Haddowia longipes. Thirteen of these compounds possessed substantial inhibitory activity against acetylcholinesterase (AChE).
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Fu Liu , Fu-shuang Li , Zi-ming Feng , Ya-nan Yang , Jian-shuang Jiang , Li Li , Pei-cheng Zhang Ten naphthalene derivatives including two unusual glycosides possessing a naphthalene-fused piceid via a [C8?-O-C6-C5-C7?]-trans-dihydrofuran ring, two flavan derivatives, as well as sixteen known phenolic compounds, were isolated from Polygonum cuspidatum. The structures were determined by extensive NMR, MS, CD data, and chemical evidence. In the in vitro neuroprotective assays, at the concentration of 10?M, five of these compounds exhibited significant effects against PC12 cells injured by rotenone.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Thomas Fester In spite of some inherent challenges, metabolite profiling is becoming increasingly popular under field conditions. It has been used successfully to address topics like species interactions, connections between growth and chemical stoichiometry or the plant’s stress response. Stress exerts a particularly clear impact on plant metabolomes and has become a central topic in many metabolite profiling experiments in the fields. In contrast to phytochambers, however, external stress is often at least partially absorbed by the environment when measuring under field conditions. Such stress-buffering capacities of (agro)-ecosystems are of crucial interest given the ever-increasing anthropogenic impact on ecosystems and this review promotes the idea of using plant metabolite profiles for respective measurements. More specifically I propose to use parameters of the response of key plant species to a given stress treatment as proxies for measuring and comparing stress-buffering capacities of ecosystems. Stress response parameters accessible by metabolite profiling comprise for example the intensity or duration of the impact of stress or the ability of the plant organism to recover from this impact after a given time. Analyses of ecosystem stress-buffering capacities may improve our understanding of how ecosystems cope with stress and may improve our abilities to predict ecosystem changes.
Buffering capacities of ecosystems are important properties regarding management and stability. Metabolite profiling of key plant species may be one approach to study such capacities.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Rob M. de Graaf , Sebastian Krosse , Ad E.M. Swolfs , Esra te Brinke , Nadine Prill , Roosa Leimu , Peter M. van Galen , Yanli Wang , Mark G.M. Aarts , Nicole M. van Dam Glucosinolates are secondary plant compounds typically found in members of the Brassicaceae and a few other plant families. Usually each plant species contains a specific subset of the ?130 different glucosinolates identified to date. However, intraspecific variation in glucosinolate profiles is commonly found. Sinalbin (4-hydroxybenzyl glucosinolate) so far has been identified as the main glucosinolate of the heavy metal accumulating plant species Noccaea caerulescens (Brassicaceae). However, a screening of 13 N. caerulescens populations revealed that in 10 populations a structurally related glucosinolate was found as the major component. Based on nuclear magnetic resonance (NMR) and mass spectrometry analyses of the intact glucosinolate as well as of the products formed after enzymatic conversion by sulfatase or myrosinase, this compound was identified as 4-?-rhamnosyloxy benzyl glucosinolate (glucomoringin). So far, glucomoringin had only been reported as the main glucosinolate of Moringa spp. (Moringaceae) which are tropical tree species. There was no apparent relation between the level of soil pollution at the location of origin, and the presence of glucomoringin. The isothiocyanate that is formed after conversion of glucomoringin is a potent antimicrobial and antitumor agent. It has yet to be established whether glucomoringin or its breakdown product have an added benefit to the plant in its natural habitat.
Publication date: Available online 4 February 2015 Source:Phytochemistry Author(s): Dugassa Nemie-Feyissa , Behzad Heidari , Mickael Blaise , Cathrine Lillo The two Arabidopsis basic-helix-loop-helix transcription factors GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3) are positive regulators of anthocyanin biosynthesis, and form protein complexes (MBW complexes) with various R2R3 MYB transcription factors and a WD40 repeat protein TRANSPARENT TESTA GLABROUS1 (TTG1). In earlier studies, GL3, in contrast to EGL3, was shown to be essential for accumulation of anthocyanins in response to nitrogen depletion. This could not be fully explained by the strong induction of GL3 in response to nitrogen depletion because the EGL3 transcripts were constitutively at a relatively high level and transcripts levels of the two genes were similar under nitrogen depletion. Here the GL3 and EGL3 proteins were characterized with respect to their affinities for PRODUCTION OF ANTHOCYANIN PIGMENT2 (PAP2), a R2R3-MYB which is induced by nitrogen depletion and is part of MBW complexes promoting anthocyanin synthesis. GL3 and EGL3 were also tested for their binding to MYBL2, a negative regulator of anthocyanin synthesis and MBW complexes. Using heterologously expressed proteins and Microscale Thermophoresis, GL3 showed binding constants (Kd) of 3.5±1.7 and 22.7±3.7?M, whereas EGL3 showed binding constants of 7.5±2.3 and 8.9±1.4?M for PAP2 and MYBL2, respectively. This implies that MYBL2 will not inhibit a MBW complex containing GL3 as easily as for a complex containing EGL3. In transgenic plants where EGL3 reaches high concentrations compared with MYBL2 the equilibrium is shifted and MYBL2 is not likely to be an efficient competitor, hence anthocyanin formation could be restored by either EGL3 or GL3 genes when overexpressed by help of the 35S promoter. The present work underpins that GL3 is essential for anthocyanin accumulation under nitrogen depletion not only due to transcriptional activation, but also because of binding properties to proteins promoting or inhibiting the activity of the MBW complex.
Publication date: Available online 31 January 2015 Source:Phytochemistry Author(s): Sondès Rahoui , Abdelilah Chaoui , Cécile Ben , Martina Rickauer , Laurent Gentzbittel , Ezzeddine El Ferjani Six Medicago truncatula genotypes differing in cadmium susceptibility were used to test the effect of this heavy metal on mineral, carbohydrate and amino acid supply in growing radicles. Cadmium treatment caused alteration of macronutrient (Ca and K), microelement (Fe, Zn and Cu), carbohydrate (total soluble sugars (TSS), glucose, fructose and sucrose) and free amino acid (FAAS) accumulations. These mobilization changes differed in the tested genotypes. Carbohydrates were determining to susceptible lines’ growth in control condition; free amino acids enabled tolerant lines to counteract cadmium intrusion. Transcriptional changes in response to cadmium treatment were analyzed on MtMST, a gene encoding a monosaccharide transport protein. A significant down-regulation was observed in the most susceptible line TN1.11. Glucose was over-consumed in tolerant lines. Thus, glucose metabolism integrity seems essential to maintain growth under cadmium exposure. Analysis of germination medium showed solute losses at the expense of suitable mobilization to the growing embryonic axis and highlights cadmium-triggered membrane alterations. FAAS and TSS leakages were reduced in tolerant lines while monosaccharide losses were accentuated in susceptible lines. This research work gave an overview of cadmium deleterious effects on biomass mobilization and membrane integrity. Carbon metabolism is shown to be primordial to enhance early embryonic growth and nitrogen metabolism is revealed to be crucial to establish seedling growth under cadmium stress.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Yi Zhang , Hao Zhang , Zhi-Rong Zou , Yi Liu , Xiao-Hui Hu In this research, the protective effect of spermidine (Spd) in mitigating saline–alkaline stress in tomato (Solanum lycopersicum L.) at physiological and proteomic levels were examined. The results showed that saline–alkaline stress induced accumulation of H2O2 and O2?, and increased the activities of antioxidase (SOD, CAT, and POD). Spermidine efficiently alleviated the inhibitory role of saline–alkaline on plant growth and inhibited saline–alkaline stress-induced H2O2 and O2? accumulation. Proteomics investigations of the leaves of tomato seedlings, responding to a 75mM saline–alkaline solution and 0.25mM Spd, were performed. Maps of the proteome of leaf extracts were obtained by two-dimensional gel electrophoresis. An average of 49, 47 and 34 spots, which appeared repeatedly and that significantly altered the relative amounts of polypeptides by more than twofold, were detected for seedlings treated with saline–alkaline solution (S) compared to normal solution (CK), saline–alkaline plus spermidine (MS) compared to CK, or S versus MS, respectively. Thirty-nine of these proteins were identified by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and were classified into five functional categories, including energy and metabolism, signal transduction, amino acid metabolism, protein metabolism, and stress-defense response. Proteomics analysis coupled with bioinformatics indicated that Spd treatment helps tomato seedlings combat saline–alkaline stress by modulating the defense mechanism of plants and activating cellular detoxification, which protect plants from oxidative damage induced by saline–alkaline stress.
Publication date: Available online 29 January 2015 Source:Phytochemistry Author(s): Simona Birti? , Pierre Dussort , François-Xavier Pierre , Antoine C. Bily , Marc Roller Carnosic acid (salvin), which possesses antioxidative and antimicrobial properties, is increasingly exploited within the food, nutritional health and cosmetics industries. Since its first extraction from a Salvia species (?70years ago) and its identification (?50years ago), numerous articles and patents (?400) have been published on specific food and medicinal applications of Rosmarinus and Salvia plant extracts abundant in carnosic acid. In contrast, relevant biochemical, physiological or molecular studies in planta have remained rare. In this overview, recent advances in understanding of carnosic acid distribution, biosynthesis, accumulation and role in planta, and its applications are summarised. We also discuss the deficiencies in our understanding of the relevant biochemical processes, and suggest the molecular targets of carnosic acid. Finally, future perspectives and studies related to its potential roles are highlighted.
Publication date: Available online 14 January 2015 Source:Phytochemistry Author(s): Yulin Ren , Chunhua Yuan , Youcai Deng , Ragu Kanagasabai , Tran Ngoc Ninh , Vuong Tan Tu , Hee-Byung Chai , Djaja D. Soejarto , James R. Fuchs , Jack C. Yalowich , Jianhua Yu , A. Douglas Kinghorn A dichapetalin-type triterpenoid and a dibenzylbutyrolactone-type lignan, together with five known lignans, a known aromatic diterpenoid, and a known acylated phytosterol, were isolated from the aerial parts of Phyllanthus songboiensis, collected in Vietnam. Their structures were determined by interpretation of the spectroscopic data, and the inhibitory activity toward HT-29 human colon cancer cells of all isolates was evaluated by a cytotoxicity assay. The known arylnaphthalene lignan, (+)-acutissimalignan A, was highly cytotoxic toward HT-29 cells, with an IC50 value of 19 nM, but this compound was inactive as a DNA topoisomerase II? (topo II?) poison. The known phytosterol, (?)-?-sitosterol-3-O-?-d-(6-O-palmitoyl)glucopyranoside, was found to stimulate natural killer (NK) cells at a concentration of 10?M in the presence of interleukin 12 (IL-12).
Publication date: Available online 21 January 2015 Source:Phytochemistry Author(s): Miriam Payá-Milans , Mónica Venegas-Calerón , Joaquín J. Salas , Rafael Garcés , Enrique Martínez-Force The acyl-[acyl carrier protein]:sn-1-glycerol-3-phosphate acyltransferase (GPAT; E.C. 126.96.36.199) catalyzes the first step of glycerolipid assembly within the stroma of the chloroplast. In the present study, the sunflower (Helianthus annuus, L.) stromal GPAT was cloned, sequenced and characterized. We identified a single ORF of 1344base pairs that encoded a GPAT sharing strong sequence homology with the plastidial GPAT from Arabidopsis thaliana (ATS1, At1g32200). Gene expression studies showed that the highest transcript levels occurred in green tissues in which chloroplasts are abundant. The corresponding mature protein was heterologously overexpressed in Escherichia coli for purification and biochemical characterization. In vitro assays using radiolabelled acyl-ACPs and glycerol-3-phosphate as substrates revealed a strong preference for oleic versus palmitic acid, and weak activity towards stearic acid. The positional fatty acid composition of relevant chloroplast phospholipids from sunflower leaves did not reflect the in vitro GPAT specificity, suggesting a more complex scenario with mixed substrates at different concentrations, competition with other acyl-ACP consuming enzymatic reactions, etc. In summary, this study has confirmed the affinity of this enzyme which would partly explain the resistance to cold temperatures observed in sunflower plants.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Doris Gangl , Julie A.Z. Zedler , Artur W?odarczyk , Poul Erik Jensen , Saul Purton , Colin Robinson The unicellular green alga Chlamydomonas reinhardtii has potential as a cell factory for the production of recombinant proteins and other compounds, but mainstream adoption has been hindered by a scarcity of genetic tools and a need to identify products that can be generated in a cost-effective manner. A promising strategy is to use algal chloroplasts as a site for synthesis of high value bioactive compounds such as diterpenoids since these are derived from metabolic building blocks that occur naturally within the organelle. However, synthesis of these complex plant metabolites requires the introduction of membrane-associated enzymes including cytochrome P450 enzymes (P450s). Here, we show that a gene (CYP79A1) encoding a model P450 can be introduced into the C. reinhardtii chloroplast genome using a simple transformation system. The gene is stably expressed and the P450 is efficiently targeted into chloroplast membranes by means of its endogenous N-terminal anchor domain, where it is active and accounts for 0.4% of total cell protein. These results provide proof of concept for the introduction of diterpenoid synthesis pathways into the chloroplast of C. reinhardtii.
A cytochrome P450 has been expressed in Chlamydomonas chloroplasts and targeted into the membranes in an active form.
Publication date: Available online 14 January 2015 Source:Phytochemistry Author(s): Wolfgang Brandt , Kerstin Manke , Thomas Vogt Crystal structure data of cation-dependent catechol O-methyltransferases (COMTs) from mammals and related caffeoyl coenzyme A OMTs (CCoAOMTs) from plants have suggested operative molecular mechanisms. These include bivalent cations that facilitate deprotonation of vicinal aromatic dihydroxy systems and illustrate a conserved arrangement of hydroxyl and carboxyl ligands consistent with the requirements of a metal-activated catalytic mechanism. The general concept of metal-dependent deprotonation via a complexed aspartate is only one part of a more pronounced proton relay, as shown by semiempirical and DFT quantum mechanical calculations and experimental validations. A previously undetected catalytic triad, consisting of Lys157-Asn181-Asp228 residues is required for complete methyl transfer in case of a cation-dependent phenylpropanoid and flavonoid OMT, as described in this report. This triad appears essential for efficient methyl transfer to catechol-like hydroxyl group in phenolics. The observation is consistent with a catalytic lysine in the case of mammalian COMTs, but jettisons existing assumptions on the initial abstraction of the meta-hydroxyl proton to the metal stabilizing Asp154 (PFOMT) or comparable Asp-carboxyl groups in type of cation-dependent enzymes in plants. The triad is conserved among all characterized plant CCoAOMT-like enzymes, which are required not only for methylation of soluble phenylpropanoids like coumarins or monolignol monomers, but is also present in the similar microbial and mammalian cation-dependent enzymes which methylate a comparable set of substrates.
Publication date: Available online 12 January 2015 Source:Phytochemistry Author(s): Shuai Gao , Hai-Na Yu , Rui-Xue Xu , Ai-Xia Cheng , Hong-Xiang Lou Plant phenylpropanoids represent a large group of secondary metabolites which have played an important role in terrestrial plant life, beginning with the evolution of land plants from primitive green algae. 4-Coumarate: coenzyme A ligase (4CL) is a provider of activated thioester substrates within the phenylpropanoid synthesis pathway. Although 4CLs have been extensively characterized in angiosperm, gymnosperm and moss species, little is known of their functions in liverworts. Here, a 4CL homolog (designated as Pa4CL1) was isolated from the liverwort species Plagiochasma appendiculatum. The full-length cDNA sequence of Pa4CL1 contains 1644bp and is predicted to encode a protein with 547amino acids. The gene products were 40–50% identical with 4CL sequences reported in public databases. The recombinant protein was heterologously expressed in Escherichia coli and exhibited a high level of 4CL activity, catalyzing formation of hydroxycinnamate-CoA thioesters by a two-step reaction mechanism from corresponding hydroxycinnamic acids. Kinetic analysis indicated that the most favorable substrate for Pa4CL1 is p-coumaric acid. The transcription of Pa4CL1 was induced when P. appendiculatum thallus was treated with either salicylic acid or methyl jasmonate.
Publication date: Available online 12 January 2015 Source:Phytochemistry Author(s): Tamami Tokunaga , Hideo Hayashi , Kohki Akiyama A major strigolactone produced by the model legume Medicago truncatula (barrel medic) has been tentatively identified as a didehydro-orobanchol isomer. In this study, a putative didehydro-orobanchol isomer was isolated from root exudates collected from barrel medic grown hydroponically under phosphate-starved conditions. The structure and absolute configurations of this strigolactone, named medicaol, were determined by a combination of spectroscopic analysis and spectral comparison with 4-deoxymedicaol which was synthesized using solvolysis and rearrangement of hydroxymethylhexahydroindenone to tetrahydroazulenone as a key step. Medicaol has a seven-membered cycloheptadiene in the A ring instead of a typical six-membered cyclohexene. Medicaol and 4-deoxymedicaol showed activity comparable to their corresponding six-membered A ring relatives, orobanchol and 4-deoxyorobanchol (ent-2?-epi-5-deoxystrigol), in inducing hyphal branching of germinating spores of an arbuscular mycorrhizal fungus Gigaspora margarita. Plausible biosynthetic pathways from 4-deoxyorobanchol to medicaol are also proposed.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Anil Bhatia , Santosh K. Bharti , Tusha Tripathi , Anuradha Mishra , Om P. Sidhu , Raja Roy , Chandra Shekhar Nautiyal Guggul gum resin from Commiphora wightii (syn. Commiphoramukul) has been used for centuries in Ayurveda to treat a variety of ailments. The NMR and GC–MS based non-targeted metabolite profiling identified 118 chemically diverse metabolites including amino acids, fatty acids, organic acids, phenolic acids, pregnane-derivatives, steroids, sterols, sugars, sugar alcohol, terpenoids, and tocopherol from aqueous and non-aqueous extracts of leaves, stem, roots, latex and fruits of C. wightii. Out of 118, 51 structurally diverse aqueous metabolites were characterized by NMR spectroscopy. For the first time quinic acid and myo-inositol were identified as the major metabolites in C. wightii. Very high concentration of quinic acid was found in fruits (553.5±39.38mgg?1 dry wt.) and leaves (212.9±10.37mgg?1 dry wt.). Similarly, high concentration of myo-inositol (168.8±13.84mgg?1 dry wt.) was observed from fruits. The other metabolites of cosmeceutical, medicinal, nutraceutical and industrial significance such as ?-tocopherol, n-methylpyrrolidone (NMP), trans-farnesol, prostaglandin F2, protocatechuic, gallic and cinnamic acids were identified from non-aqueous extracts using GC–MS. These important metabolites have thus far not been reported from this plant. Isolation of a fungal endophyte, (Nigrospora sps.) from this plant is the first report. The fungal endophyte produced a substantial quantity of bostrycin and deoxybostrycin known for their antitumor properties. Very high concentrations of quinic acid and myo-inositol in leaves and fruits; a substantial quantity of ?-tocopherol and NMP in leaves, trans-farnesol in fruits, bostrycin and deoxybostrycin from its endophyte makes the taxa distinct, since these metabolites with medicinal properties find immense applications as dietary supplements and nutraceuticals.
Publication date: Available online 12 January 2015 Source:Phytochemistry Author(s): Yoshinori Fujimoto , Izumi Maeda , Kiyoshi Ohyama , Juri Hikiba , Hiroshi Kataoka 3?-Hydroxy-5?-cholestan-6-one was identified in the EtOAc extract of Ajuga hairy roots by micro-analysis using LC–MS/MS in the multiple reaction mode (MRM). Furthermore, administration of (2,2,4,4,7,7-2H6)- and (2,2,4,4,6,7,7-2H7)-cholesterols to the hairy roots followed by LC–MS/MS analysis of the EtOAc extract of the hairy roots indicated that cholesterol was converted to the 5?-ketone with hydrogen migration from the C-6 to the C-5 position. These findings, in conjunction with the previous observation that the ketone was efficiently converted to 20-hydroxyecdysone, strongly suggest that the 5?-ketone is an intermediate immediately formed after cholesterol during 20-hydroxyecdysone biosynthesis in Ajuga sp. In addition, the mechanism of the 5?-ketone formation from cholesterol is discussed.
Publication date: Available online 9 January 2015 Source:Phytochemistry Author(s): Xue Chen , Thu-Thuy T. Dang , Peter J. Facchini Noscapine is a phthalideisoquinoline alkaloid, which represents a class of plant specialized metabolites within the large and structurally diverse group of benzylisoquinoline alkaloids. Along with the narcotic analgesic morphine, noscapine is a major alkaloid in the latex of opium poppy (Papaver somniferum) that has long been used as a cough suppressant and has undergone extensive investigation as a potential anticancer drug. Cultivated opium poppy plants remain the only commercial source of noscapine. Despite its isolation from opium more than two centuries ago, the almost complete biosynthesis of noscapine has only recently been established based on an impressive combination of molecular genetics, functional genomics, and metabolic biochemistry. In this review, we provide a historical account of noscapine from its discovery through to initial investigations of its formation in opium poppy. We also describe recent breakthroughs that have led to an elucidation of the noscapine biosynthetic pathway, and we discuss the pharmacological properties that have prompted intensive evaluation of the potential pharmaceutical applications of noscapine and several semi-synthetic derivatives. Finally, we speculate on the future potential for the production of noscapine using metabolic engineering and synthetic biology in plants and microbes.
Publication date: Available online 9 January 2015 Source:Phytochemistry Author(s): Atsushi Kato , Yuki Hirokami , Kyoko Kinami , Yutaro Tsuji , Shota Miyawaki , Isao Adachi , Jackie Hollinshead , Robert J. Nash , J.L. Kiappes , Nicole Zitzmann , Jin K. Cha , Russell J. Molyneux , George W.J. Fleet , Naoki Asano We report the isolation and structural determination of fourteen iminosugars, containing five pyrrolizidines and five indolizidines, from Castanospermum australe. The structure of a new alkaloid was elucidated by spectroscopic methods as 6,8-diepi-castanospermine (13). Our side-by-side comparison between bicyclic and corresponding monocyclic iminosugars revealed that inhibition potency and spectrum against each enzyme are clearly changed by their core structures. Castanospermine (10) and 1-deoxynojirimycin (DNJ) have a common d-gluco configuration, and they showed the expected similar inhibition potency and spectrum. In sharp contrast, 6-epi-castanospermine (12) and 1-deoxymannojirimycin (manno-DNJ) both have the d-manno configuration but the ?-mannosidase inhibition of 6-epi-castanospermine (12) was much better than that of manno-DNJ. 6,8-Diepi-castanospermine (13) could be regarded as a bicyclic derivative of talo-DNJ, but it showed a complete loss of ?-galactosidase A inhibition. This behavior against ?-galactosidase A is similar to that observed for 1-epi-australine (6) and altro-DMDP.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Tomáš ?ezanka , Jaromír Lukavský , Karel Sigler , Linda Nedbalová , Milada Vítová This study describes the identification of regioisomers and enantiomers of triacylglycerols of C20 polyunsaturated fatty acids (PUFAs) in the alga Trachydiscus minutus cultivated at different temperatures using reversed- and chiral-phase liquid chromatography–mass spectrometry. The use of the two different phases contributes to ready identification, both qualitative and semiquantitative, of regioisomers and enantiomers of triacylglycerols containing eicosapentaenoic and arachidonic in the molecule. The ratio of regioisomers and enantiomers of triacylglycerols (TAG) depends on the temperature of cultivation; with lowering temperature the proportion of the achiral TAG increases and the enantiomer ratio diverges from 1:1.
Publication date: Available online 9 January 2015 Source:Phytochemistry Author(s): Malinna Jusoh , Saw Hong Loh , Tse Seng Chuah , Ahmad Aziz , Thye San Cha Microalgae lipids and oils are potential candidates for renewable biodiesel. Many microalgae species accumulate a substantial amount of lipids and oils under environmental stresses. However, low growth rate under these adverse conditions account for the decrease in overall biomass productivity which directly influence the oil yield. This study was undertaken to investigate the effect of exogenously added auxin (indole-3-acetic acid; IAA) on the oil content, fatty acid compositions, and the expression of fatty acid biosynthetic genes in Chlorella vulgaris (UMT-M1). Auxin has been shown to regulate growth and metabolite production of several microalgae. Results showed that oil accumulation was highest on days after treatment (DAT)-2 with enriched levels of palmitic (C16:0) and stearic (C18:0) acids, while the linoleic (C18:2) and ?-linolenic (C18:3n3) acids levels were markedly reduced by IAA. The elevated levels of saturated fatty acids (C16:0 and C18:0) were consistent with high expression of the ?-ketoacyl ACP synthase I (KAS I) gene, while low expression of omega-6 fatty acid desaturase (?-6 FAD) gene was consistent with low production of C18:2. However, the increment of stearoyl-ACP desaturase (SAD) gene expression upon IAA induction did not coincide with oleic acid (C18:1) production. The expression of omega-3 fatty acid desaturase (?-3 FAD) gene showed a positive correlation with the synthesis of PUFA and C18:3n3.
Publication date: Available online 2 January 2015 Source:Phytochemistry Author(s): Russell J. Chedgy , Tobias G. Köllner , C. Peter Constabel Salicinoids are phenolic glycosides (PGs) characteristic of the Salicaceae and are known defenses against insect herbivory. Common examples are salicin, salicortin, tremuloidin, and tremulacin, which accumulate to high concentrations in the leaves and bark of willows and poplars. Although their biosynthetic pathway is not known, recent work has suggested that benzyl benzoate may be a potential biosynthetic intermediate. Two candidate genes, named PtACT47 and PtACT49, encoding BAHD-type acyl transferases were identified and are predicted to produce such benzylated secondary metabolites. Herein described are the cDNA cloning, heterologous expression and in vitro functional characterization of these two BAHD acyltransferases. Recombinant PtACT47 exhibited low substrate selectivity and could utilize acetyl-CoA, benzoyl-CoA, and cinnamoyl-CoA as acyl donors with a variety of alcohols as acyl acceptors. This enzyme showed the greatest Km/Kcat ratio (45.8nM?1s?1) and lowest Km values (45.1?M) with benzoyl-CoA and salicyl alcohol, and was named benzoyl-CoA: salicyl alcohol O-benzoyltransferase (PtSABT). Recombinant PtACT49 utilized a narrower range of substrates, including benzoyl-CoA and acetyl-CoA and a limited number of alcohols. Its highest Km/Kcat (31.8nM?1s?1) and lowest Km (55.3?M) were observed for benzoyl-CoA and benzyl alcohol, and it was named benzoyl-CoA: benzyl alcohol O-benzoyltransferase (PtBEBT). Both enzymes were also capable of synthesizing plant volatile alcohol esters, such as hexenyl benzoate, at trace levels. Although the activities demonstrated are consistent with roles in salicinoid biosynthesis, direct tests of this hypothesis using transgenic poplar must still be performed.
Publication date: Available online 6 January 2015 Source:Phytochemistry Author(s): Youping Zhou , Hilary Stuart-Williams , Kliti Grice , Zachary E. Kayler , Saša Zavadlav , Angela Vogts , Florian Rommerskirchen , Graham D. Farquhar , Arthur Gessler It has long been theorized that carbon allocation, in addition to the carbon source and to kinetic isotopic effects associated with a particular lipid biosynthetic pathway, plays an important role in shaping the carbon isotopic composition (13C/12C) of lipids (Park and Epstein, 1961). If the latter two factors are properly constrained, valuable information about carbon allocation during lipid biosynthesis can be obtained from carbon isotope measurements. Published work of Chikaraishi et al. (2004) showed that leaf lipids isotopic shifts from bulk leaf tissue ??13Cbk?lp (defined as ?13Cbulkleaftissue??13Clipid) are pathway dependent: the acetogenic (ACT) pathway synthesizing fatty lipids has the largest isotopic shift, the mevalonic acid (MVA) pathway synthesizing sterols the lowest and the phytol synthesizing 1-deoxy-d-xylulose 5-phosphate (DXP) pathway gives intermediate values. The differences in ??13Cbk?lp between C3 and C4 plants are also pathway-dependent: >> . These pathway-dependent differences have been interpreted as resulting from kinetic isotopic effect differences of key but unspecified biochemical reactions involved in lipids biosynthesis between C3 and C4 plants. After quantitatively considering isotopic shifts caused by (dark) respiration, export-of-carbon (to sink tissues) and photorespiration, we propose that the pathway-specific differences can be successfully explained by C4?C3 carbon allocation (flux) differences with greatest flux into the ACT pathway and lowest into the MVA pathways (when flux is higher, isotopic shift relative to source is smaller). Highest carbon allocation to the ACT pathway appears to be tied to the most stringent role of water-loss-minimization by leaf waxes (composed mainly of fatty lipids) while the lowest carbon allocation to the MVA pathway can be largely explained by the fact that sterols act as regulatory hormones and membrane fluidity modulators in rather low concentrations.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Carina Verónica González , Martín Leandro Fanzone , Leandro Emanuel Cortés , Rubén Bottini , Diego Claudio Lijavetzky , Carlos Luis Ballaré , Hernán Esteban Boccalandro Sunlight exposure has multiple effect on fruits, as it affects the light climate perceived by fruit photoreceptors and fruit tissue temperature. In grapes (Vitis vinifera L.), light exposure can have a strong effect on fruit quality and commercial value; however, the mechanisms of light action are not well understood. The role of fruit-localized photoreceptors in the control of berry quality traits was evaluated under field conditions in a commercial vineyard in Mendoza (Argentina). Characterization of the diurnal dynamics of the fruit light environment in a vertical trellis system indicated that clusters were shaded by leaves during most of the photoperiod. Supplementation of the fruit light environment from 20days before veraison until technological harvest showed that red (R, 660nm) and blue (B, 470nm) light strongly increased total phenolic compound levels at harvest in the berry skins without affecting sugar content, acidity or berry size. Far-red (FR, 730nm) and green (G, 560nm) light supplementation had relatively small effects. The stimulation of berry phytochromes and cryptochromes favored accumulation of flavonoid and non-flavonoid compounds, including anthocyanins, flavonols, flavanols, phenolic acids and stilbenes. These results demonstrate that the chemical composition of grape berries is modulated by the light quality received by the clusters under field conditions, and that fruit photoreceptors are not saturated even in areas of high insolation and under management systems that are considered to result in a relatively high exposure of fruits to solar radiation. Therefore, manipulation of the light environment or the light sensitivity of fruits could have significant effects on critical grape quality traits.
Publication date: January 2015 Source:Phytochemistry, Volume 109 Author(s): Jonathon Roepke , Gale G. Bozzo Kaempferol and quercetin 3-O-?-glucoside-7-O-?-rhamnoside (K3G7R and Q3G7R, respectively) are major flavonol bisglycosides accumulating in Arabidopsis thaliana with synergistic abiotic stresses (i.e., nitrogen deficiency and low temperature, NDLT). However, these molecules disappear rapidly during recovery from NDLT. Typically, catabolism of related chemicals relies on ?-glucosidase (BGLU) action. Evidence for flavonol 3-O-?-glucoside-7-O-?-rhamnoside BGLU activity is provided here. Major losses of Q3G7R and K3G7R coincided with an approximate 250% induction in flavonol 3-O-?-glucoside-7-O-?-rhamnoside BGLU activity within 2days of NDLT recovery relative to plants cultured under nitrogen sufficiency and high temperature (NSHT, control). QTOF-MS/MS established the product of Q3G7R hydrolysis in the presence of Arabidopsis cell free extracts was quercetin 7-O-?-rhamnoside. A phylogenetic analysis of the Arabidopsis glycoside hydrolase family 1 identified BGLU15 (At2g44450) and five other members that cluster with Fabaceae hydrolases known to attack isoflavones and isoflavonoids, which are structurally somewhat related to flavonol 3-O-?-glucoside-7-O-?-rhamnosides. Real time quantitative PCR analysis established a 300% higher expression of BGLU15 within 1day of the recovery from NDLT relative to control plants; lower or negligible changes in expression were evident for the remaining BGLUs. Recombinant thioredoxin-His6-tagged mature BGLU15 protein was expressed in Escherichia coli and purified to homogeneity. A comparison of a wide spectrum of ?-glucosides showed that recombinant BGLU15 preferentially hydrolyses the 3-O-?-glucosides of flavonols, but does not attack quercetin 3-O-?-rhamnoside, quercetin 3-O-?-galactoside and rutin. BGLU15 displayed the highest catalytic efficiency for Q3G7R and K3G7R yielding their respective 7-O-rhamnosides as products; flavonol 3-O-glucosides were also attacked, albeit with lower efficiency. Together, it appears the loss of flavonol 3-O-?-glucoside-7-O-?-rhamnosides in Arabidopsis is dependent upon the enzyme-mediated cleavage of the 3-O-? linked glucose moiety.
Publication date: January 2015 Source:Phytochemistry, Volume 109 Author(s): Nadine Meitinger , Daniel Geiger , Thierry W. Augusto , Rodrigo Maia de Pádua , Wolfgang Kreis The isomerization of 5-pregnene-3,20-dione into 4-pregnene-3,20-dione was investigated to shed further light on cardenolide biosynthesis and to characterize the enzymes involved in cardenolide formation. It was shown that the ?5-3-ketosteroid isomerase of Digitalis lanata, which catalyzes this isomerization, is an individual enzyme and not, as previously thought, associated with ?5-3?-hydroxysteroid dehydrogenase. The enzyme was purified by fractionated ammonium sulfate precipitation, hydrophobic interaction chromatography and gel filtration. The purification protocol resulted in a 68.1-fold enriched specific enzyme activity with a yield of 2.2%. After an additional chromatofocusing step the 3KSI activity appeared as a single protein band at 17kDa in SDS–PAGE. Plant 3KSI displayed similar properties to microbial 3-ketosteroid isomerases.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Lionel Faure , Ronaldo Cavazos , Bibi Rafeiza Khan , Robby A. Petros , Peter Koulen , Elison B. Blancaflor , Kent D. Chapman Alkamides and N-acylethanolamines (NAEs) are bioactive, amide-linked lipids that influence plant development. Alkamides are restricted to several families of higher plants and some fungi, whereas NAEs are widespread signaling molecules in both plants and animals. Fatty acid amide hydrolase (FAAH) has been described as a key contributor to NAE hydrolysis; however, no enzyme has been associated with alkamide degradation in plants. Herein reported is synthesis of 12 compounds structurally similar to a naturally occurring alkamide (N-isobutyl-(2E,6Z,8E)decatrienamide or affinin) with different acyl compositions more similar to plant NAEs and various amino alkyl head groups. These “hybrid” synthetic alkamides were tested for activity toward recombinant Arabidopsis FAAH and for their effects on plant development (i.e., cotyledon expansion and primary root length). A substantial increase in FAAH activity was discovered toward NAEs in vitro in the presence of some of these synthetic alkamides, such as N-ethyllauroylamide (4). This “enhancement” effect was found to be due, at least in part, to relief from product inhibition of FAAH by ethanolamine, and not due to an alteration in the oligomerization state of the FAAH enzyme. For several of these alkamides, an inhibition of seedling growth was observed with greater results in FAAH knockouts and less in FAAH over-expressing plants, suggesting that these alkamides could be hydrolyzed by FAAH in planta. The tight regulation of NAE levels in vivo appears to be important for proper seedling establishment, and as such, some of these synthetic alkamides may be useful pharmacological tools to manipulate the effects of NAEs in situ.
Publication date: January 2015 Source:Phytochemistry, Volume 109 Author(s): Laura Carmona-Salazar , Mohammed El Hafidi , Nora Gutiérrez-Nájera , Liliana Noyola-Martínez , Ariadna González-Solís , Marina Gavilanes-Ruíz It is essential to establish the composition of the plant plasma membrane in order to understand its organization and behavior under continually changing environments. Knowledge of the lipid phase, in particular the fatty acid (FA) complex repertoire, is important since FAs determine many of the physical–chemical membrane properties. FAs are constituents of the membrane glycerolipid and sphingolipid backbones and can also be linked to some sterols. In addition, FAs are components of complex lipids that can constitute membrane micro-domains, and the use of detergent-resistant membranes is a common approach to study their composition. The diversity and cellular allocation of the membrane lipids containing FAs are very diverse and the approaches to analyze them provide only general information. In this work, a detailed FA analysis was performed using highly purified plasma membranes from bean leaves and germinating maize embryos and their respective detergent-resistant membrane preparations. The analyses showed the presence of a significant amount of very long chain FAs (containing 28C, 30C and 32C), in both plasma membrane preparations from bean and maize, that have not been previously reported. Herein is demonstrated that a significant enrichment of very long chain saturated FAs and saturated FAs can occur in detergent-resistant membrane preparations, as compared to the plasma membranes from both plant species. Considering that a thorough analysis of FAs is rarely performed in purified plasma membranes and detergent-resistant membranes, this work provides qualitative and quantitative evidence on the contributions of the length and saturation of FAs to the organization of the plant plasma membrane and detergent-resistant membranes.
Publication date: January 2015 Source:Phytochemistry, Volume 109 Author(s): Abdulmagid Alabdul Magid , Hamid Morjani , Dominique Harakat , Claudie Madoulet , Vincent Dumontet , Catherine Lavaud Seven triterpenoid glycosides, named meliosmosides A–G, were isolated from the leaves of Meliosma henryi Diels (Sabiaceae). Their structures were elucidated by different spectroscopic methods including 1D and 2D NMR experiments as well as HRESIMS analysis. Isolated compounds were evaluated for their cytotoxic activity against KB cell line.
Publication date: January 2015 Source:Phytochemistry, Volume 109 Author(s): Chrysoula Gousiadou , Tetsuo Kokubun , Charlotte H. Gotfredsen , Søren R. Jensen From Manulea altissima (Scrophulariaceae) were isolated five known secoiridoid glucosides sweroside, eustomoside, eustoside, secoxyloganin and secologanoside as well as the 4?-O-rhamnopyranosyl-feruloyl ester of adoxosidic acid, named altissimoside. Also, the caffeoyl phenylethanoid glycoside verbascoside was isolated. In addition two previously unknown terpenoid esters of 6?-hydroxy 8-epi-boschnaloside, named manucoside A and B were isolated from a formerly obtained fraction from the work-up of Manulea corymbosa. The distribution of iridoid glucosides in the Scrophulariaceae is discussed.
Publication date: February 2015 Source:Phytochemistry, Volume 110 Author(s): Marília Almeida Trapp , Marco Kai , Axel Mithöfer , Edson Rodrigues-Filho Bioassay-guided fractionation of Alternanthera brasiliana stem extracts resulted in the isolation of an antibiotically active fraction. Five human pathogenic bacteria were used to guide the fractionation process for the isolation of antimicrobial compounds. Finally, 17 linoleate oxylipins were identified by LC–MS/MS and NMR spectroscopy. Five of the isolated compounds present in A. brasiliana tissues were also detected to be synthesized by endophytic bacteria of the genus Bacillus that were isolated from A. brasiliana. It is speculated that the antibiotic oxylipins from A. brasiliana might derive from bacteria and be involved in an ecological relationship between this plant and its endophytes.
Publication date: January 2015 Source:Phytochemistry, Volume 109 Author(s): Alessio Cimmino , Mónica Fernández-Aparicio , Fabiana Avolio , Koichi Yoneyama , Diego Rubiales , Antonio Evidente Orobanche and Phelipanche species (the broomrapes) are root parasitic plants, some of which represent serious weed problems causing heavy yield losses on important crops. Current control relies on the use of certain agronomic practices, resistant crop varieties, and herbicides, albeit success has been marginal. Agronomic practices such as the use of allelopathic species in intercropping or cover crops, or the use of direct seedling over residues of allelopathic species incorporate the principle of allelopathy exerted by molecules exuded from roots or released by crop residues to control broomrapes. In addition, the isolation of natural substances from root exudates of plants with potential to inhibit broomrape development opens the door to the design of new herbicides based on natural and benign sources. Ryecyanatines A and B and ryecarbonitrilines A and B, the first new substituted cyanatophenol, substituted cyanatobenzo[1,3]dioxole, and the latter two new substituted benzo[1,3]dioxolecarbonitriles were isolated from rye (Secale cereale L.) root exudates. They were characterized as 4-cyanato-2-methoxyphenol, 2-cyanato-benzo[1,3]dioxole, 2-methoxybenzo[1,3]dioxole-5-carbonitrile and benzo[1,3]dioxole-2-carbonitrile by spectroscopic (essentially NMR and HRESI MS spectra) methods. These compounds were investigated for allelopathic activity on Orobanche germination and development. Ryecarbonitriline A induced germination of Orobanche cumana seeds, and this germination can be considered as suicidal because O. cumana does not parasite rye roots and cannot survive without host resources beyond germination stage. In addition, ryecyanatine A promotes a rapid cessation of O. cumana, Orobanche crenata and Orobanche minor radicle growth with the promotion of a layer of papillae at the radicle tip in O. cumana and O. crenata hampering the contact of the parasite to the host. Ryecarbonitriline B also displayed the same activity although being less active than ryecyanatine A and mainly restricted to O. cumana.
Posted on 6 February 2015 | 9:12 am
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