Showing papers on "Xanthone published in 1989"
TL;DR: Swertiabisxanthone-I as discussed by the authors was isolated from Swertia macrosperma and its structure elucidated as 1,3,5,8-tetrahydroxy-7-(1,1.3, 3, 5, 8, 5, 8, 8, 2.2′-xanthonyl) xanthone by 1 H, 13 C NMR and mass spectral evidence.
44 citations
TL;DR: Four new prenylated xanthones are isolated from the bark of Cudrania cochinchinensis, named gerontoxanthones E, G, H and I, along with the known xanthone, cUDraniaxanthone.
37 citations
TL;DR: In this paper, three prenylated xanthones, 1−3, have been isolated from the root bark of Garcinia gerrardii and structure elucidation was achieved by a combination of one-and two-dimensional NMR spectroscopic techniques, including long-range HETCOR, mass spectroscopy, and chemical methods.
Abstract: Three novel prenylated xanthones, 1–3, have been isolated from the root bark of Garcinia gerrardii HARVEYex T. R. SIM (G. natalensis SCHLECHTER; G. transvaalensis BURTT DAVY; Guttiferae). Structure elucidation was achieved by a combination of one- and two-dimensional NMR spectroscopic techniques, including long-range HETCOR, mass spectroscopy, and chemical methods. Garcigerrin A (1) and B (2) are pyrano derivatives of 3. They all show a rare 1,4,5 oxygenation pattern of the xanthone nucleus. Xanthone 3 is fungicidal against Cladosporium cucumerinum.
35 citations
TL;DR: Two new xanthone glucosides, 2,3,7-trimethoxyxanthone-1- O -glucoside and 2, 3,5-tricyclic Xanthone 1-Oglucose, were isolated from the whole plant of Halenia elliptica and identified through their acetates as mentioned in this paper.
16 citations
13 citations
TL;DR: The molecular structure of gaseous xanthone has been determined from electron diffraction data as mentioned in this paper, showing that the molecule is planar and has C 2v symmetry, and that the benzene ring in the molecule was assumed to be a regular hexagon in the analysis, but the symmetry of the ring appeared to be lower.
12 citations
TL;DR: Sapxanthone, a novel xanthone with a polyfunctional side chain, has been isolated along with 1,8-dihydroxy-3,5-dimetboxy-9H-xanthen-9-one from Saponaria vaccaria.
10 citations
8 citations
TL;DR: In this paper, the triplet state of xanthone embedded in a cyclodextrin cavity was studied using time-resolved ESR, and the specific spin polarization induced through triplet-triplet energy transfer between aromatic molecules proves some fixed orientation of the energy donor and acceptor in γ-cyclodextrins.
8 citations
Journal Article•
7 citations
01 Jul 1989
TL;DR: In this article, the 0-0 bands of the first electronic transitions of monomer, dimer, and tetramer in MP are at 334.6 nm (room temperature), 346.7 nm (132 K), and 357.7nm (101 K), respectively.
Abstract: Absorption spectra of xanthone have been measured in polyethylene film, a 1:1 mixture of methanol and ethanol, a 1:1 mixture of methylcyclohexane and isopentane (MP) at various temperatures. It is found that xanthone forms dimer and tetramer in MP at low temperatures. As for the dimer, phosphorescence and its excitation spectra have been observed. From comparison of the observed and the MO calculated results, assignment of the electronic bands has been made. The 0-0 bands of the first electronic transitions of monomer, dimer, and tetramer in MP are at 334.6 nm (room temperature), 346.7 nm (132 K), and 357.7 nm (101 K), respectively. The structure of the dimer is considered to be a C2 sandwich type.
TL;DR: The incorporation of synthetic deuterium-labeled moniliphenone into chloromonilicin and into its xanthone precursor, 4-chloropinselin, was confirmed by ’H-NMR spectrometry.
Abstract: The biosynthetic route for chloromonilicin, an antifungal substance from cherry rot fungus, was investigated using deuterium-labeled precursors. The incorporation of synthetic deuterium-labeled moniliphenone into chloromonilicin and into its xanthone precursor, 4-chloropinselin, was confirmed by ’H-NMR spectrometry.
Journal Article•
TL;DR: The 2-Hydroxyacetyl-7-acetylxanthone (V) was synthesized in four steps starting from xanthene, by two synthetic approaches as discussed by the authors.
Abstract: 2-Hydroxyacetyl-7-acetylxanthone (V), a new xanthone derivative, was synthesized in four steps starting from xanthene, by two synthetic approaches. The new compound displayed antianaphylactic activity in the PCA test and in the anaphylaxis shock test in rats. It also displayed analgesic activity in the writhing test in mice, and antiinflammatory activity in the carrageenin edema test in rats. The activity of the new compound has been tentatively interpreted on the basis of its chemical and structural analogy with known drugs.
TL;DR: A new xanthone was isolated from the trunk wood of Haploclathra leiantha and H. paniculata and its structure determined by UV, IR, NMR and mass spectrometry as 1,3,7-trihydroxy-8methoxyxanthone.
TL;DR: Vaccaxanthone, a 7-carboxy-1,3,5,8-tetraoxygenated xanthone has been isolated from Saponaria vaccaria as mentioned in this paper.
Abstract: Vaccaxanthone, a novel 7-carboxy-1,3,5,8-tetraoxygenated xanthone has been isolated from Saponaria vaccaria. its structure has been established from spectroscopic data including uv, ir, high resolution-ms, 1 H- and 13 C-nmr as 1,8-dihydroxy-3,5-dimethoxyxanthone-7-carboxylic acid
TL;DR: In this article, two xanthones from Centaurium limarifolium were identified based on their spectral data, and the synthesis of these two compounds was performed to confirm the assigned structures.
Abstract: From Centaurium limarifolium several new xanthones were isolated; two were identified on the basis of their spectral data. We describe the synthesis of this two compounds, performed to confirm the assigned structures
TL;DR: In this article, the 0-0 bands of the first electronic transitions of monomer, dimer, and tetramer in MP are at 334.6 nm (room temperature), 346.7 nm (132 K), and 357.7nm (101 K), respectively.
Abstract: Absorption spectra of xanthone have been measured in polyethylene film, a 1:1 mixture of methanol and ethanol, a 1:1 mixture of methylcyclohexane and isopentane (MP) at various temperatures. It is found that xanthone forms dimer and tetramer in MP at low temperatures. As for the dimer, phosphorescence and its excitation spectra have been observed. From comparison of the observed and the MO calculated results, assignment of the electronic bands has been made. The 0-0 bands of the first electronic transitions of monomer, dimer, and tetramer in MP are at 334.6 nm (room temperature), 346.7 nm (132 K), and 357.7 nm (101 K), respectively. The structure of the dimer is considered to be a C2 sandwich type.