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PubMed2006

Bioactive polyacetylenes in food plants of the Apiaceae family: occurrence, bioactivity and analysis.

Many bioactive compounds with known effects on human physiology and disease have been identified through studies of plants used in traditional medicine. Some of these substances occur also in common food plants, and hence could play a significant role in relation to human health. Food plants of the Apiaceae plant family such as carrots, celery and parsley, contain a group of bioactive aliphatic C17-polyacetylenes. These polyacetylenes have shown to be highly toxic towards fungi, bacteria, and mammalian cells, and to display neurotoxic, anti-inflammatory and anti-platelet-aggregatory effects and to be responsible for allergic skin reactions. The effect of these polyacetylenes towards human cancer cells, their human bioavailability and their ability to reduce tumour formation in a mammalian in vivo model indicates that they may also provide benefits for health. The present state of knowledge on the occurrence of polyacetylenes in Apiaceae food plants, their biochemistry and bioactivity is presented in this review as well as relatively new methods for the isolation and quantification of these compounds from plants, plant products and biological fluids.

Acetylene↗
PubMed2003

Membrane binding and permeation by indolicidin analogs studied by a biomimetic lipid/polydiacetylene vesicle assay.

Membrane binding and relative penetration of indolicidin analogs were studied using lipid/polydiacetylene (PDA) chromatic biomimetic membranes. Colorimetric and fluorescence analyses determined that an indolicidin analog with a proline and tryptophan residue substituted with lysines showed more pronounced bilayer surface interactions, while indolicidin and particularly an indolicidin analog in which all prolines were replaced with alanine residues exhibited deeper insertion into the lipid bilayer. The colorimetric data demonstrated that more pronounced blue-red transitions were observed when the chromatic vesicles incorporated lipopolysaccharide (LPS) within the lipid bilayer, indicating that LPS promoted preferred binding and incorporation of the peptides at the lipid/water interface. The fluorescence quenching experiments further confirmed this outcome. The results indicate that the antibacterial activity of indolicidin most likely requires initial binding to the LPS moieties within bacterial membranes, as well as disruption of the bilayer interface. The degree of hemolysis induced by the analogs, on the other hand, correlated to the extent of penetration into the hydrophobic core of the lipid assembly.

Acetylene↗
PubMed2003

Quantitative interactions between cryptdin-4 amino terminal variants and membranes.

Paneth cells secrete alpha-defensins into the lumen from the base of small intestinal crypts, and cryptdin-4 (Crp4) is the most potent mouse alpha-defensin in vitro. Purified recombinant Crp4 and Crp4 variants with (des-Gly)-, (Gly1Val)-, (Gly1Asp)-, and (Gly1Arg)-substitutions were all bactericidal with Crp4 and (Gly1Arg)-Crp4 being slightly more active than other variants. Bactericidal activities correlated directly with permeabilization of live Escherichia coli, with equilibrium binding to E. coli membrane phospholipid bilayers and vesicles, and with induced graded fluorophore leakage from phospholipid vesicles. The Crp4 peptide N-terminus affects bactericidal activity modestly, apparently by influencing peptide binding to phospholipid bilayers and subsequent permeabilization of target cell membranes.

Acetylene↗
PubMed2006

Isolation and structure elucidation of cytotoxic polyacetylenes and polyenes from Echinacea pallida.

Bioassay-guided fractionation of n-hexane extracts of Echinacea pallida (Asteraceae) roots led to the isolation and structure elucidation of two polyacetylenes (1, 3) and three polyenes (2, 4, 5). Two are known hydroxylated compounds, namely 8-hydroxy-pentadeca-(9E)-ene-11,13-diyn-2-one (1) and 8-hydroxy-pentadeca-(9E,13Z)-dien-11-yn-2-one (2). Two dicarbonylic constituents, namely pentadeca-(9E)-ene-11,13-diyne-2,8-dione (3) and pentadeca-(9E,13Z)-dien-11-yne-2,8-dione (4), were isolated and characterized for the first time. Furthermore, the structure elucidation of pentadeca-(8Z,13Z)-dien-11-yn-2-one (5) is described. The structure of the compounds isolated was determined on the basis of UV, IR, NMR (including 1D and 2D NMR experiments, such as 1H-1H gCOSY, gHSQC-DEPT, gHMBC, gNOESY) and MS spectroscopic data. The cytotoxic activity of the isolated constituents against MIA PaCa-2 human pancreatic adenocarcinoma cells was evaluated in the concentration range 1-100 microg/ml. Results show that the hydroxylated compounds (1, 2) have low cytotoxicity, while the more hydrophobic polyacetylenes (3) and polyenes (4, 5) displayed moderate activity.

Acetylene↗
PubMed2003

Detection and analysis of membrane interactions by a biomimetic colorimetric lipid/polydiacetylene assay.

We describe applications of a colorimetric assay based on supramolecular assemblies of lipid-polydiacetylene vesicles for analysis and screening of membrane interactions of lipophilic enzymes, peptides, and ions and for study of the effects of lipid composition upon membrane properties. The lipid-polymer aggregates undergo visible and quantifiable blue-to-red transitions following interfacial interactions and perturbation by varied biochemical processes. Specifically, we show that the colorimetric assay can be tuned for selective detection of enzymes reacting with different lipid species. The experiments also demonstrate that the lipid/polymer platform facilitates screening of peptide-membrane interactions in multicomponent mixtures. The colorimetric vesicles can incorporate lipid species from different cellular sources facilitating analysis of the contribution of molecular components to membrane properties and lipid interactions.

Acetylene↗
PubMed2002

Morphological manipulation of bolaamphiphilic polydiacetylene assemblies by controlled lipid doping.

Morphological transformations of bolaamphiphilic polydiacetylene (L-Glu-Bis-3) lipid assemblies from helical ribbons to vesicles and flat sheets through controlled doping are described, and the role of specific lipid dopants in these processes is discussed. Upon doping with cell surface receptor G(M1) ganglioside, fluid vesicular structures start to emerge, coexisting with the micro-crystalline helical ribbons. The vesicle formation is further facilitated and stabilized by the introduction of cholesterol into the system, presumably through surface curvature variation induced by inhomogeneous distribution and dynamic clustering of G(M1) and cholesterol within the doped assemblies. Extended helical ribbons are "truncated" into patches of flat sheets when a sufficient amount of Bis-1, a structurally compatible symmetric bolaamphiphilic diacetylene lipid, is doped. The results reaffirm the important roles of packing geometry and headgroup chirality in the formation of extended helical ribbon structures. The doped assemblies of bolaamphiphiles allow for capture of intermediate structures of morphological transformation using transmission electron microscopy (TEM). A vesicle-to-ribbon transformation mechanism via lateral reorganization within relatively fluid vesicular microstructures has been suggested. Understanding of the doping-induced transformation process provides useful information for the design of advanced materials where the microscopic morphology of material is crucial to its function.

Acetylene↗
PubMed2003

Polyacetylene glycosides from Pratia nummularia cultures.

Two polyacetylene glycosides, lobetyol 9-O-glc(6)-(1)rha (pratialin-A) and lobetyol 9-O-glc(6)-(1)glc(6)-(1)glc (pratialin-B), were isolated from Pratia nummularia (Campanulaceae) callus and hairy root cultures and their chemical structures were determined by analysis of spectroscopic data. From the methanol extract of the hairy root cultures, together with the known polyacetylene constituents lobetyol, lobetyolin, and lobetyolinin, tryptophan was also isolated. This report is the first example of the isolation and structure elucidation of rutinoside (pratialin-A) and triglucoside (pratialin-B) derivatives of polyacetylene constituents.

Acetylene↗
PubMed1999

Immunosuppressive and anti-inflammatory effects of methanolic extract and the polyacetylene isolated from Bidens pilosa L.

The immunomodulatory effect of the methanolic extract obtained from dried leaves of Bidens pilosa L. (Asteraceae) and the polyacetylene 2-O-beta-D-glucosyltrideca-11 E-en-3,5,7,9-tetrayn-1,2-diol (PA-1) isolated from it was investigated. The extract inhibited the proliferative response in two in vitro models: human lymphocytes stimulated by 5 microg ml(-1) phytohemagglutinin (PHA) or to 100 nM 12-O-tetradecanoyl phorbol-13-acetate (TPA) plus 0.15 microM ionomycin and murine lymphocytes stimulated by 5 microg ml(-1) concanavalin A (Con A) or in the mixed leukocyte reaction (IC50 = 12.5 to 25 microg ml(-1)). PA-1 was 10-told more potent than the original extract in blocking both human and murine lymphocyte proliferation (IC50 = 1.25 to 2.5 microg ml(-1)). In mice, the intraperitoneal (i.p.) administration of methanolic extract of B. pilosa significantly reduced the size of the popliteal lymph node (PLN) after the inflammation induced by zymosan. One week after the injection of zymosan (150 microg) in the foot pad, PLN weighed 4.6 +/- 0.6 mg in comparison with 0.5 +/- 0.07 mg of the contralateral non-inflamed foot pad. The i.p. treatment with 10 mg extract from day 2 to day 6 after zymosan injection reduced the PLN weight to 1.8 +/- 0.3 mg. The data suggest an immunosuppressive activity of components of B. pilosa that may explain its popularly perceived anti-inflammatory effect.

Acetylene↗
PubMed2000

Statistical analysis of elicitation strategies for thiarubrine A production in hairy root cultures of Ambrosia artemisiifolia.

Elicitation strategies were studied for yield enhancement of thiarubrine A, a secondary metabolite and a potential pharmaceutical, produced by hairy root cultures of Ambrosia artemisiifolia. Abiotic elicitation was performed using vanadyl sulfate solution and biotic elicitation using autoclaved cell wall filtrates of the fungi Protomyces gravidus, a pathogen of A. artemisiifolia and Botrytis cinereae. The factors considered were age of the culture, concentration of the elicitor used and the time period of exposure or contact. Statistical methods were used to determine the strength of the interaction between the various factors and their response on the yield of the secondary metabolite. The maximum increase in the yield relative to the control, 8-fold corresponding to 569 microg g(-1) of biomass, was observed when 16-day-old cultures were elicited with 50 mg l(-1) of vanadyl sulfate for a time period of 72 h. The maximum yield of 647 microg g(-1) was achieved when the cultures were exposed to 5 microM autoclaved cell wall filtrates of P. gravidus for a time period of 48 h. The yield increase was 3-fold in the case of elicitation with autoclaved cell wall filtrates of B. cinereae. The methodology used in this report can be extended to determine the optimum conditions of other elicitors.

Alkynes↗
PubMedDate not supplied

A semiconductive polymer film sensor for glucose.

The electrical conductivity of organic polymers such as polyacetylene and its derivatives can be varied over twelve orders of magnitude with small amounts (0-3%) of various dopants, such as iodine, bromine, and perchloric acid. Semiconductive polyacetylene film doped with iodine is sensitive to hydrogen peroxide, and can be used as a quantitative hydrogen peroxide sensor. A rapid, quantitative sensor for glucose, using the flavoprotein glucose oxidase, is described and introduces a novel electroactive material, polyacetylene, as the basis for a new biosensor. A significant increase in the sensitivity of this device has been obtained by mediating the doping reaction through lactoperoxidase and potassium iodide.

Acetylene↗
PubMed2002

Polyacetylenes from a marine sponge Petrosia sp. inhibit DNA replication at the level of initiation.

In the course of our search for bioactive metabolites from the marine sponges collected from Korean water, we found that the polyacetylenes of marine sponge, genus Petrosia, deliver significant selective cytotoxicity against several human tumor cell lines. The effects of polyacetylene on DNA replication were examined using simian virus 40 DNA replication system in vitro. We found that polyacetylenes inhibited DNA replication, and predominantly inhibited the initiation stage of DNA replication. Polyacetylenes inhibited the DNA cleavage by topoisomerase I, and also significantly reduced polymerase alpha-primase activity. The ssDNA binding activity of replication protein A was little affected by polyacetylenes. We suggest that polyacetylenes might inhibit proteins required to establish replication forks during the initiation reaction, and their cytotoxicities might be related to the inhibitory effect they have on this fundamental cellular process.

Acetylene↗
PubMed1998

Hepatoprotective and nitric oxide production inhibitory activities of coumarin and polyacetylene constituents from the roots of Angelica furcijuga.

The methanolic extract from the roots of Angelica furcijuga KITAGAWA was found to exhibit protective effects on liver injury induced by D-galactosamine (D-GalN) and lipopolysaccharide (LPS). From the methanolic extract, seventeen coumarins, two phenylpropanoids, and two polyacetylenes were isolated and examined their in vitro and in vivo hepatoprotective effects and inhibitory activity of NO production in macrophages. A acylated khellactone, isoepoxypteryxin, showed protective activity against D-GalN-induced cytotoxicity in primary cultured rat hepatocytes. On the other hand, six acylated khellactones (hyuganins A, B, C, and D, anomalin, isopteryxin) and two polyacetylenes [(-)-falcarinol and falcarindiol] strongly inhibited NO production induced by LPS in cultured mouse peritoneal macrophages, and also other acylated khellactones (isoepoxypteryxin, pteryxin, and suksdorfin) and a coumarin glycosides (praeroside II) were found to show the activity. By comparison of the inhibitory activities for acylated khellactones with those for other coumarins, acyl groups were found to be essential to exerting potent activity.

Acetylene↗
PubMed1998

Interfacial catalysis by phospholipases at conjugated lipid vesicles: colorimetric detection and NMR spectroscopy.

BACKGROUND: Self-assembled conjugated polymers are rapidly finding biological and biotechnological applications. This work describes a synthetic membrane system based on self-assembled polydiacetylenes, which are responsive to the enzymatic activity of phospholipases - a ubiquitous class of enzymes that catalyze the hydrolysis of phospholipid molecules embedded in cell membranes. RESULTS: We show that phospholipases are active at bilayer vesicles composed of the natural enzyme substrate, dimyristoylphosphatidylcholine (DMPC), and a synthetic pi-conjugated polymerized lipid based on polydiacetylene (PDA). In addition, the enzymatic reaction induces an optical transition in the surrounding PDA matrix, visible to the naked eye. Nuclear magnetic resonance spectroscopy confirms the occurrence of enzymatic catalysis and reveals the fate of the cleavage products. CONCLUSIONS: The results indicate that the structural and color changes of the PDA matrix are directly related to interfacial catalysis by phospholipase. This novel biocatalytic method of inducing optical transitions in conjugated polymers might lead to new approaches towards rapidly screening new enzyme inhibitor compounds.

Acetylene↗
PubMed2001

Ab initio calculations of electronically excited states of cyano-substituted polyacetylene cations.

The transition energies for the lowest energy pi --> pi* electronic excitations are calculated with the complete active space self-consistent field method (CASSCF) and with the complete active space second-order perturbation theory method (CASPT2) for the linear cyano-substituted polyacetylene cations, H-Cn-CN+, n = 4-11, and NC-Cn-CN+, n = 2-10. These systems are models for an important class of interstellar species. We demonstrate the utility of the theoretical calculations in assigning the experimental spectra.

Acetylene↗
PubMed2002

Electrochemical and Raman studies of the biointeraction between Escherichia coli and mannose in polydiacetylene derivative supported on the self-assembled monolayers of octadecanethiol on a gold electrode.

Here, we describe a new method to study the biointeraction between Escherichia coli and mannose by using supramolecular assemblies composed of polydiacetylene supported on the self-assembled monolayer of octadecanethiol on a gold electrode. These prepared bilayer materials simply are an excellent protosystem to study a range of important sensor-related issues. The experimental results from UV-vis spectroscopy, resonance Raman spectroscopy, and electrochemistry confirm that the specific interactions between E. coli and mannose can cause conformational changes of the polydiacetylene backbone rather than simple nonspecific adsorption. Moreover, the direct electrochemical detection by polydiacetylene supramolecular assemblies not only opens a new path for the use of these membranes in the area of biosensor development but also offers new possibilities for diagnostic applications and screening for binding ligands.

Acetylene↗
PubMed2006

pH response of carboxy-terminated colorimetric polydiacetylene vesicles.

Carboxy-terminated polydiacetylene vesicles are known to undergo dramatic color transitions in response to exposure to external stimuli such as pH, temperature, and receptor-ligand binding. FTIR spectroscopy was used to identify the breakdown in the interfacial hydrogen-bonding interactions of the carboxylic acid headgroups of polymerized 10,12-tricosadiynoic acid (TRCDA) vesicles in aqueous solution during pH chromic transition. The headgroup structure was monitored as the chromic transition takes place and the dissociation dependence of the pKa was determined. Due to the attenuated acidity of the interfacially confined carboxy groups, which exhibit pKa values in the range 9.5-9.9, it was found that the deprotonation-triggered blue-red chromic transition occurred in the pH range 9.0-10.1 and that the mechanism of the transition required interaction with the surface carboxyl group, which is of importance in the design of a biochromic mechanism using PDA assemblies. Transmission electron microscopy and FTIR spectroscopy revealed that the surface ionization and the pH-induced chromogenic transition was also accompanied by a dramatic vesicle-planar morphological transition alongside subtle changes to the alkyl chain conformation and packing. A two-step mechanism was implicated as causing the chromic transition that first involves surface deprotonation and then specific cation binding, which can aid the design of sensitive surface-ligand chemistry for new PDA structures.

Binding Sites↗
PubMed2005

Functional polyacetylenes.

Polyacetylene (PA) is a Nobel Prize-winning macromolecule. In this work, PA is molecularly functionalized, which endows it with an array of new functional properties. The molecular functionalization is realized by attachment of functional pendants to the polyene backbone. Our efforts in the catalyst exploration and reaction optimization have led to the syntheses of a large number of PA derivatives carrying functional groups. Polymer reactions are exploited as an alternative route to the functional PAs that are difficult or impossible to access by direct polymerizations of their monomers. The new PAs with appropriate backbone-pendant combinations show various functional properties such as liquid crystallinity, photoconductivity, light emission, ionic susceptibility, photoresistance, chromism, helical chirality, optical nonlinearity, self-assembly, cytocompatibility, and bioactivity. The properties of the PAs are tuned internally and manipulated externally: the former is achieved by changing their molecular structures, especially their functional pendants, while the latter is accomplished by applying thermal, mechanical, electrical, photonic, and chemical stimuli.

Acetylene↗
PubMed2000

Peptide-membrane interactions studied by a new phospholipid/polydiacetylene colorimetric vesicle assay.

Interactions between peptides and lipid membranes play major roles in numerous physiological processes, such as signaling, cytolysis, formation of ion channels, and cellular recognition. We describe a new colorimetric technique for studying peptide-membrane interactions. The new assay is based on supramolecular assemblies composed of phospholipids embedded in a matrix of polydiacetylene (PDA) molecules. The phospholipid/PDA vesicle solutions undergo visible color changes upon binding of membrane peptides. Experiments utilizing various analytical techniques confirm that the blue-to-red color transitions of the phospholipid/PDA vesicles are directly related to adoption of helical conformations by the peptides and their association with the lipids. Spectroscopic data indicate that the colorimetric transitions are correlated with important molecular parameters, such as the degree of penetration of the peptides into lipid bilayers, and the mechanisms of peptide-lipid binding. The results suggest that the new colorimetric assay could be utilized for studying interactions and organization of membrane peptides.

Acetylene↗