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[structure: see text] Callyberynes A and B, polyacetylenic hydrocarbons from Callyspongia sp., have been synthesized for the first time using highly convergent approaches based on optimized Cadiot-Chodkiewicz (Alami, Vasella) and sequential Sonogashira cross-coupling reactions.
Cirsium rhinoceros Nakai (Compositae) is a herbaceous perennial native to Korea, whole plant of which has been used in folklore medicine. C. rhinoceros was extracted by a standard extraction procedure. Its n-hexane, CHCl3 and n-BuOH extracts were fractionated by column chromatography to provide a polyacetylene, a coumarin and five flavonoids. Ciryneol C, scopoletin, acacetin, cirsimarin were isolated for the first time from this plant.
Novel lamellar nanocomposites composed of exfoliated SbP2O8- nanosheets and poly(N-methyl-2-ethynyl pyridinium iodide) (PNMe) or poly(N-octadecyl-2-ethynyl pyridinium bromide) (PNO) have been synthesized by exfoliation and re-stacking method. The XRD data of the nanocomposites SbP2O8-:PNMe and PNO:SbP2O8- indicate the formation of nanostructures containing SbP2O8- nanosheets and PNMe or PNO with interlayer expansions of 2.22 and 4.2 nm along the stacking direction of SbP2O8- nanosheets. Formation of these nanocomposites is further supported by the results obtained by FT-IR spectroscopy, scanning transmission electron microscopy and thermogravimetry. The values of electrical conductivity of the polymers and nanocomposites have also been measured.
The isolation and structure elucidation of 1 from the Basidomycete fungus Baeospora myosura is described. This new ene-triyne antibiotic was most potent against Gram-positive bacteria, while it was less active against Gram-negative bacteria and a yeast. MICs against several strains of Staphylococcus aureus were as low as 0.001 microg/mL. Analogues of 1 that did not contain the ene-triyne moiety were inactive against all microorganisms tested. The isolation of this new natural product was complicated by the highly reactive nature of the conjugated terminal polyacetylene.
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.
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.
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.
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.
A new polyacetylenic acid, callyspongynic acid (1), was isolated as an alpha-glucosidase inhibitor from the marine sponge Callyspongia truncata. Its structure was determined by spectroscopic and chemical methods.
alpha-Terthienyl and 5 polyacetylenes were examined for chromosome damaging activity using Syrian hamster cells. None of these naturally occurring compounds induced sister chromatid exchanges and neither alpha-terthienyl nor phenylheptatriyne induced chromosome aberrations.
We report the direct evidence for the macromolecular helicity inversion of a helical poly(phenylacetylene) bearing l- or d-alanine pendants with a long alkyl chain in different solvents by atomic force microscopy observations of the diastereomeric helical structures. The diastereomeric helical poly(phenylacetylene)s induced in polar and nonpolar solvents self-assembled into ordered, two-dimensional helix bundles with controlled molecular packing, helical pitch, and handedness on graphite upon exposure of each solvent. The macromolecular helicity deposited on graphite from a polar solvent further inverted to the opposite handedness by exposure to a specific nonpolar solvent, and these changes in the surface chirality based on the inversion of helicity could be visualized by atomic force microscopy with molecular resolution, and the results were quantified by X-ray diffraction of the oriented liquid crystalline, diastereomeric helical polymer films.
The CH2Cl2 extract of the leaves of Orophea enneandra displayed antifungal, antioxidant, and radical scavenging properties in bioautographic TLC assays. To obtain rapid information on the active compounds, on-flow LC/1H NMR and LC/UV/MS analyses of the antioxidant fraction were performed. The on-line information led rapidly to the partial identification of three closely related lignans, one tocopherol derivative, and one polyacetylene. This approach necessitated, however, large quantities to be injected to obtain satisfactory on-flow LC/1H NMR spectra, and isolation of the compounds was necessary to obtain complete NMR data. These compounds were isolated and identified as (-)-phylligenin (1), (-)-eudesmin (2), (-)-epieudesmin (3), polycerasoidol (4), and oropheic acid (5), a new polyacetylene. Their activities against the 2, 2-diphenyl-1-picrylhydrazyl radical and the fungus Cladosporium cucumerinum were investigated. This paper indicates the possibilities and limits of on-flow LC/1H NMR in this type of study.
Nine new polyacetylenes, triangulynes A-H (1-8) and triangulynic acid (9), have been isolated from the marine sponge Pellina triangulata (Oceanapiidae) through cytotoxicity-guided fractionation. Structural elucidations and stereochemistry assignments were based on chemical and spectral studies.
The Indonesian marine sponge Callyspongia pseudoreticulata was found to contain (3S,18S,4E,16E)-eicosa-1,19-diyne-3,18-diol-4,16-diene (1), the structure of which was determined by detailed spectroscopic analysis. Its absolute configuration was established using the modified Mosher's method after esterification of the secondary alcohols with Mosher's reagent.
Callyspongamide A (1), a new cytotoxic polyacetylenic amide, has been isolated from the marine sponge Callyspongia fistularis collected in the Red Sea. Callyspongamide A is an amide derivative of a C(17)-polyacetylenic acid and phenethylamine. It represents a new class of secondary metabolites within the family Callyspongiidae. Its structure was determined on the basis of 1D and 2D (COSY, HOHAHA, HMQC, and HMBC) NMR studies and high-resolution mass spectral measurement.
Structural and retrostructural analysis of helical dendronized polyacetylenes (i.e., self-organizable polyacetylenes containing first generation dendrons or minidendrons as side groups) synthesized by the polymerization of minidendritic acetylenes with [Rh(nbd)Cl]2 (nbd = 2,5-norbornadiene) reveals an approximately 10% change in the average column stratum thickness (l) of the cylindrical macromolecules with a chiral periphery, through which a strong preference for a single-handed screw-sense is communicated. The cylindrical macromolecules reversibly interconvert between a three-dimensional (3D) centered rectangular lattice (Phi r-c,k) exhibiting long-range intracolumnar helical order at lower temperatures and a two-dimensional (2D) hexagonal columnar lattice (Phi h) with short-range helical order at higher temperatures. A polymer containing chiral, nonracemic peripheral alkyl tails is found to have a larger l as compared to the achiral polymers. In methyl cyclohexane solution, the same polymer exhibits an intense signal in circular dichroism (CD) spectra, whose intensity decreases upon heating. The observed change in l indicates that the chiral tails alter the polymer conformation from that of the corresponding polymer with achiral side chains. This change in conformation results in a relatively large free energy difference (DeltaGh) favoring one helix-sense over the other (per monomer residue). The capacity to distort the polymer conformation and corresponding free energy is related to the population of branches in the chiral tails and their distance from the polymer backbone by comparison to recently reported first and second generation dendronized polyphenylacetylenes.
Investigation of the organic extract of a Red Sea sponge, Callyspongia sp., resulted in isolation and identification of three new C(22)-polyacetylenic alcohols, callyspongenols A-C (1-3), together with dehydroisophonochalynol (4). The structures of 1-3 were determined by 1D and 2D NMR studies and mass spectral determinations. Compounds 1-4 showed moderate cytotoxicity against P388 and HeLa cells.
Four novel straight-chain polyacetylenic alcohols were isolated from a marine ascidian (Phylum Chordata, subphyllum Urochordata) collected off Vigo, along the Atlantic coast of northwestern Spain. The chemical structures, which exhibit an uncommon dienyne group, were characterized by spectroscopic methods, mainly mono- and bi-dimensional NMR. This is the first finding of acetylenic lipids from an organism belonging to phylum Chordata.