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PubMed2005

In situ simultaneous analysis of polyacetylenes, carotenoids and polysaccharides in carrot roots.

This paper presents an approach to simultaneously analyze polyacetylenes, carotenoids, and polysaccharides in carrot (Daucus carota L.) roots by means of Raman spectroscopy. The components were measured in situ in the plant tissue without any preliminary sample preparation. The analysis is based on the intensive and characteristic key bands observed in the Raman spectrum of carrot root. The molecular structures of the main carrot polyacetylenes, falcarinol and falcarindiol, are similar, but their Raman spectra exhibit specific differences demonstrated by the shift of their -C[triple bond]C- mode from 2258 to 2252 cm(-)(1), respectively. Carotenoids can be identified by -C=C- stretching vibrations (about 1520 and 1155 cm(-)(1)) of the conjugated system of their polyene chain, whereas the characteristic Raman band at 478 cm(-)(1) indicates the skeletal vibration mode of starch molecule. The other polysaccharide, pectin, can be identified by the characteristic band at 854 cm(-)(1), which is due to the -C-O-C- skeletal mode of alpha-anomer carbohydrates. The Raman mapping technique applied here has revealed detailed information regarding the relative distribution of polyacetylenes, carotenoids, starch, and pectin in the investigated plant tissues. The distribution of these components varies among various carrot cultivars, and especially a significant difference can be seen between cultivated carrot and the wild relative D. carota ssp. maritimus.

Acetylene↗
PubMed2006

Simultaneous determination of ginsenosides and polyacetylenes in American ginseng root (Panax quinquefolium L.) by high-performance liquid chromatography.

A method for simultaneous determination of ginsenosides and polyacetylenes in Panax quinquefolium L. (American ginseng) roots was developed. The ginsenosides Rb1, Rb2, Rc, Rd, Re, Rg1, Ro, malonyl-Rb1, malonyl-Rc, and malonyl-Rd and the polyacetylenes falcarinol and panaxydol were extracted from fresh ginseng roots in a sequential extraction process with 100% methanol followed by 80% aqueous methanol and quantified simultaneously in extracts by high-performance liquid chromatography using diode array detection. Separations were achieved with a phosphate buffer-acetonitrile gradient system using an RP-C18 column. Except for Rd, the present extraction method resulted in similar or significantly higher concentrations of both ginsenosides and polyacetylenes in comparison to commonly used extraction methods for these compounds. The contents of polyacetylenes and ginsenosides were determined in the root hairs, lateral roots, and main roots of 6 year old ginseng plants. The total mean concentrations of ginsenosides and polyacetylenes in root hairs were 31.0 g/kg fresh weight (FW) and 2.6 g/kg FW, respectively, whereas the concentrations of these bioactive compounds in the main roots were significantly lower with total mean concentrations of 17.8 g/kg FW for ginsenosides and 0.6 g/kg FW for polyacetylenes. The concentration of individual and total ginsenosides and polyacetylenes did not differ significantly between main roots of different sizes. Consequently, it is possible to do quantitative screening for ginsenosides and polyacetylenes to breed ginseng roots with higher levels of bioactive compounds.

Chromatography, High Pressure Liquid↗
PubMed2001

First total synthesis of (-)-ichthyothereol and its acetate.

The first and stereoselective total syntheses of (-)-ichthyothereol (1) and its acetate ((+)-2) were achieved by incorporation of the two chiral centers of diethyl L-tartrate. The starting diethyl L-tartrate was converted into trans-2-ethynyl-3-hydroxytetrahydropyran 14 in a stereoselective manner via the endo mode cyclization of the epoxy-alkyne derivative 12. The alcohol 12 was then transformed into (E)-iodoolefin derivative 15, which was exposed to a coupling reaction with 1-tributylstannyl-1,3,5-heptyne (19), derived from the corresponding 1-trimethylsilyl-1,3,5-heptyne (18), under Stille conditions to produce the all-carbon framework of the target natural products. Chemical modification of the coupled product 20 under conventional conditions completed the first total synthesis of (-)-ichthyothereol (1) and its acetate ((+)-2).

Alkynes↗
PubMed2004

Total synthesis of (S)-(-)-(E)-15,16-dihydrominquartynoic acid: a highly potent anticancer agent.

The conjugated entriyne natural product, (S)-(E)-15,16-dihydrominquartynoic acid (1), is synthesized in five linear steps and 30% overall yield from the known aldehyde 11. The key step is a one-pot in situ desilylation/Cadiot-Chodkiewicz coupling reaction affording the entriyne unit. The bromoalkyne 6 with an omega-carboxylic acid group was found to undergo a copper-catalyzed cross-coupling reaction producing the desired diyne intermediate 10, while the corresponding omega-ester bromoalkyne 14 failed to couple with triethylsilylacetylene under a variety of conditions.

Alkynes↗
PubMed2006

Synthesis of marine polyacetylenes callyberynes A-C by transition-metal-catalyzed cross-coupling reactions to sp centers.

Efficient total syntheses of the sponge-derived hydrocarbon polyacetylenes callyberynes A-C have been achieved using metal-catalyzed cross-coupling reactions of highly unsaturated 1,3-diyne fragments as the key steps, namely: Cadiot-Chodkiewicz reaction under Alami's optimized conditions (sp-sp), sequential Sonogashira reaction of a cis,cis-divinyl dihalide (sp2-sp), and Kumada-Corriu reaction of an unactivated alkyl iodide (sp3-sp). This last approach constitutes the first application of a metal-catalyzed sp3-sp Kumada-Corriu cross-coupling reaction to the synthesis of a natural product.

Animals↗
PubMed2005

Raman microspectroscopic study on polymerization and degradation processes of a diacetylene derivative at surface enhanced Raman scattering active substrates. 2. Confocal Raman microscopic observation of polydiacetylene adsorbed on active sites.

Confocal Raman microscopic measurements were performed at room temperature on the Langmuir-Blodgett (LB) monolayer of 10,12-pentacosadiynoic acid (DA) prepared on surface enhanced Raman scattering (SERS) active Ag island films, two-dimensional (2D) Raman images of which exhibit bright and dim spots on a dark background. The measurements performed by focusing the excitation laser light (488 nm) on the dark background indicate the prompt appearance of the Raman bands (1515 and 2115 cm(-1)) due to polydiacetylene (PDA) in the red phase and subsequent diminution of the Raman bands. On the other hand, the spectra observed by focusing the excitation laser spot on the dim and bright spots exhibit almost random fluctuations, giving rather narrow Raman bands in the 1620-1000 cm(-1) region, which appear and disappear temporarily with varying intensities under the continuous irradiation at 488 nm. Broad Raman bands appear around 1580 and 1360 cm(-1), which are ascribable to amorphous carbon, at a later stage of the observation, the intensities from the bright spot being more than 100 times stronger than those from the dim spot. The narrow bands are ascribed to a series of carbonaceous intermediates such as polyenes, graphite sheets with various sizes, and folded or reorganized forms of the sheets including carbon nanotubes and fullerenes, which are formed during the conversion of PDA to amorphous carbon. The random spectral fluctuation was interpreted by considering that the intermediates undergo thermally activated diffusion and get temporarily in contact with the SERS-active site, resulting in the enhancement of their Raman bands and the fluctuation.

Adsorption↗
PubMed2005

Size effect of polydiacetylene vesicles functionalized with glycolipids on their colorimetric detection ability.

In this paper, the size effect of the polydiacetylene vesicles functionalized with glycolipids on their colorimetric detection ability has been studied. Polydiacetylene vesicles in which were incorporated glycolipids acted as a model system for the affinochromatic property. Visible color changes from blue to red could be observed to the naked eye owing to Con A binding to the sugar moiety and be detected quantitatively by the visible absorption spectrum. In the experiment, small and uniform vesicles were obtained after extrusion through membranes with different pore sizes. The morphology and mean size distribution of the extruded vesicles were studied by transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. Our work shows that the smaller the vesicles are, the stronger is the effect, making the detection of Con A easier. The results may apply to the sensitivity enhancement of polydiacetylene biosensors for the recognition of other biomolecules.

Colorimetry↗
PubMed2004

Microscopic visualization of alamethicin incorporation into model membrane monolayers.

Lipid interactions and cooperative assembly properties are fundamental determinants for the action of antimicrobial membrane-active peptides. Here we analyze the interactions and aggregation properties of alamethicin, an antimicrobial pore-forming peptide, with films formed at the air/water interface. Surface-area/pressure isotherms, Brewster angle microscopy, and fluorescence-confocal microscopy provided detailed information on the morphologies and structural properties of the peptide and its effect on the film components. The pressure-area analysis and microscopy experiments facilitated unprecedented visualization of the structural consequences of alamethicin association at the air/water interface, with pure phospholipid films, and within mixed phospholipid/polydiacetylene (PDA) films. The analysis exposed the kinetic features and the interplay between the peptide aggregates and film constituents. In particular, the results demonstrate the use of phospholipid/PDA film assemblies for studying membrane-peptide association and interactions within two-dimensional films.

Acetylene↗
PubMed2005

Vesicular polydiacetylene sensor for colorimetric signaling of bacterial pore-forming toxin.

A vesicle-based polydiacetylene biosensor for colorimetric detection of bacterial pore-forming toxin streptolysin O (SLO) is reported. The sensor was constructed with three lipid constituents: glycine-terminated diacetylene lipid Gly-PCDA, cell membrane-mimicking component PC-DIYNE, and cholesterol (CHO), which serves as the bait molecule. UV irradiation led to photopolymerization of the diacetylene lipids that gave the material a blue appearance. Incubation of the vesicles with SLO from Streptococcus pyrogenes turned the vesicle solution red, and the color change was found to be correlated to SLO concentration. The optimal sensing performance was found with vesicles consisting of 71% Gly-PCDA, 25% CHO, and 4% PC-DIYNE, and a correlation relationship was obtained for 20 HU to 500 HU/mL, or 100 pM to 6.3 nM of SLO toxin. Transmission electron microscopy and dynamic light scattering was used for further characterization of the vesicular assemblies. Transmembrane pores (holes) with diameter around 30 nm were observed on the vesicle membranes, in particular on the peripheral of the membrane structures, suggesting pore formation by SLO toxin provides the driving force for the color change of the functional vesicles.

Acetylene↗
PubMed2006

Manipulating FRET with polymeric vesicles: development of a "mix-and-detect" type fluorescence sensor for bacterial toxin.

A simple "mix-and-detect" type of fluorescence sensor for cholera toxin (CT) is reported. The sensor consists of a BODIPY lipid dye and polydiacetylene (PDA) vesicles and utilizes the lipid insertion and FRET mechanism to offer a direct and fluorescence "turn-on" detection of the analyte. BODIPY conjugated GM1, dissolved in a Tris buffer through aggregate formation, demonstrated substantial fluorescence quenching with addition of PDA vesicle solution. The close proximity of the dye molecules to the conjugated chains as a result of lipid insertion enables energy transfer from dye to the polymer backbone, yielding the observed phenomenon. When CT is present, the binding of BO-GM1 to CT results in formation of a complex that prohibits it from membrane insertion, leading to the blocking of the quenching process. The fluorescence signal was found to be proportional to the CT concentration. The method is very simple and allows specific and sensitive detection of the protein toxin with just a few mixing steps. It can be further developed into a general sensing strategy for detection of other proteins with amplified FRET mechanism.

Biosensing Techniques↗
PubMed2000

Polyacetylenes from a red sea sponge Callyspongia species.

From the methanolic extract of the Red Sea sponge Callyspongia sp. six new polyacetylenic compounds, aikupikanynes A-F, together with octahydrosiphonochalyne, were isolated and identified. Their structures, which comprise four hydrocarbons, two alcohols, and one unprecedented alpha-hydroxy carboxylic acid, were determined by extensive 1D and 2D NMR studies and mass spectral determinations.

Acetylene↗
PubMed2001

Cytotoxic polyacetylenes from the twigs of Ochanostachys amentacea.

Bioassay-guided investigation of the twigs of Ochanostachys amentacea using LNCaP (hormone-dependent human prostate cancer) cells as a monitor led to the isolation of three alkynes, the known (S)-17-hydroxy-9,11,13,15-octadecatetraynoic acid (minquartynoic acid, 1) and two novel analogues, (S)-17,18-dihydroxy-9,11,13,15-octadecatetraynoic acid (2) and (S)-17-hydroxy-15E-octadecen-9,11,13-triynoic acid (3). Compounds 1-3 were tested against a panel of human tumor cell lines and found to be significantly cytotoxic.

Alkynes↗
PubMed2001

Cytotoxic polyacetylenic alcohols from the marine sponge Petrosia species.

New polyacetylenic alcohols (1-5) have been isolated as cytotoxic principles from the marine sponge Petrosia sp. The compounds were particularly cytotoxic against a human melanoma cell line (SK-MEL-2). The gross structures were established on the basis of NMR and MS data, and the absolute configuration was determined by the modified Mosher's method.

Acetylene↗
PubMed2001

Polyacetylene carboxylic acids from Mitrephora celebica.

A new polyacetylene carboxylic acid, 13(E),17-octadecadiene-9,11-diynoic acid (13,14-dihydrooropheic acid, 1), and the known 17-octadecene-9,11,13-triynoic acid (oropheic acid, 2) were isolated from the stem bark of Mitrephora celebica through bioassay-guided fractionation. Both compounds demonstrated significant activity against methicillin-resistant Staphylococcus aureus and Mycobacterium smegmatis.

Acetylene↗
PubMed2002

Gymnasterkoreaynes A-F, cytotoxic polyacetylenes from Gymnaster koraiensis.

Six new polyacetylenes, gymnasterkoreaynes A-F (1-6), were isolated from the roots of Gymnaster koraiensis, together with 2,9,16-heptadecatrien-4,6-diyn-8-ol (7) and 1,9,16-heptadecatriene-4,6-diyn-3,8-diol (8), by bioassay-guided fractionation using the L1210 tumor cell line as a model for cytotoxicity. The structures of compounds 1-6 were established spectroscopically, which included 2D NMR experiments. Gymnasterkoreaynes A-F (1-6) are linear diacetylenes and are structurally related to falcarinol, panaxynol, panaxydiol, and panaxytriol. Of the compounds isolated, gymnasterkoreaynes B (2), C (3), F (6), and 1,9,16-heptadecatrien-4,6-diyn-3,8-diol (8) exhibited significant cytotoxicity against L1210 tumor cells with ED(50) values of 0.12-3.3 microg/mL.

Acetylene↗
PubMed2002

Corticatic acids D and E, polyacetylenic geranylgeranyltransferase type I inhibitors, from the marine sponge Petrosia corticata.

Two new polyacetylenic acids, corticatic acids D (2) and E (3), have been isolated from the marine sponge Petrosia corticata along with the known corticatic acid A (1) as geranylgeranyltransferase type I (GGTase I) inhibitors. Their structures were elucidated on the basis of spectroscopic and chemical methods. Compounds 1-3 inhibited GGTase I from Candida albicans with IC(50) values of 1.9-7.3 microM.

Alkyl and Aryl Transferases↗
PubMed2003

Brominated polyacetylenes from the Philippines sponge Diplastrella sp.

Five novel brominated polyacetylenic diols, diplynes A-E (2-6), and three sulfated analogues, diplyne A 1-sulfate (7), diplyne C 1-sulfate (8), and 2-deoxydiplyne D sulfate (9), were isolated from the Philippines sponge Diplastrella sp. by employing bioassay-guided fractionation using the HIV-1 integrase inhibition assay. The novel metabolites were characterized by interpretation of spectroscopic data.

Acetylene↗