Showing papers on "Xanthone published in 1986"
TL;DR: While the fluorescence of xanthone, thioxanthone and N-methylacridone shows the customary red shift with increasing solvent polarity, as measured by a polarization function, indicating an increase in dipole moment on excitation, the triplet-triplet (T1Tn) absorption spectra are strongly blue shifted, indicating a decrease in dipoles moment on the excitation as discussed by the authors.
49 citations
35 citations
TL;DR: Yellow ring-fission metabolite appears to be 4-hydroxy-3-(2'-oxo-3-trans-butenoate)-coumarin, based on its nuclear magnetic resonance spectrum and mass spectral fragmentation pattern, indicating that ring cleavage of 3,4-dihydroxyxanthone was by an extra-diol (meta- fission) mechanism.
Abstract: This study examined the catabolism of xanthone by an Arthrobacter sp. (strain GFB100) capable of growth on xanthone as its main source of carbon and energy. An early catabolic intermediate was 3,4-dihydroxyxanthone. This compound was isolated from the growth medium of a mutant strain of the Arthrobacter sp. which lacked the xanthone-inducible dihydroxyxanthone ring-fission dioxygenase of the wild-type strain. Cell extracts from wild-type xanthone-grown cells oxidized 3,4-dihydroxyxanthone to a yellow ring-fission metabolite. The same yellow compound accumulated in xanthone-grown cultures of a spontaneous mutant which lacked an active, xanthone-inducible, NADPH-linked ring-fission metabolite reductase. The yellow ring-fission metabolite appears to be 4-hydroxy-3-(2'-oxo-3-trans-butenoate)-coumarin, based on its nuclear magnetic resonance spectrum and mass spectral fragmentation pattern, indicating that ring cleavage of 3,4-dihydroxyxanthone was by an extra-diol (meta-fission) mechanism. Enzymatic analyses indicated that growth on xanthone induced a complete gentisate pathway: dioxygenase-catalyzed cleavage of gentisate to maleylpyruvate, isomerization of maleylpyruvate to fumarylpyruvate, and hydrolysis of fumarylpyruvate to fumarate and pyruvate. 4-Hydroxycoumarin was thought to be a likely pathway intermediate linking the early xanthone catabolic steps to the gentisate pathway, since 2-hydroxyacetophenone, a byproduct of 4-hydroxycoumarin hydrolysis, was formed when wild-type cells were cultured with xanthone. Chlorinated 2-hydroxyacetophenones were also obtained from specific chloro-substituted xanthones.
29 citations
17 citations
TL;DR: On etudie par une technique de CIDEP le mecanisme de formation du radical de type cyclohexadienyle par mesure de l'effet du solvant sur la reaction d'enlevement d'hydrogene de la xanthone a l'etat triplet par Sn(C 4 H 9 ) 3 H as discussed by the authors.
Abstract: On etudie par une technique de CIDEP le mecanisme de formation du radical de type cyclohexadienyle par mesure de l'effet du solvant sur la reaction d'enlevement d'hydrogene de la xanthone a l'etat triplet par Sn(C 4 H 9 ) 3 H
11 citations
10 citations
TL;DR: A new xanthone was isolated from the trunk wood of Haploclathra paniculata and its structure determined by UV, IR, NMR and mass spectrometry as 3,7-dihydroxy-1,8-dimethoxyxanthone.
9 citations
TL;DR: In this article, a comminuted herb was extracted exhaustively with hot 70% ethanol, the extract was concentrated and diluted with water (1:2) and was treated successively with petroleum ether (I) with chloroform (II), and with chlorofornr-ethyl acetate (2:1) (III).
Abstract: To isolate the coumarins, the comminuted herb was extracted exhaustively with hot 70% ethanol, the extract was concentrated and diluted with water (1:2) and was treated successively with petroleum ether (I) with chloroform (II), and with chlorofornr-ethyl acetate (2:1) (III) [i]. The combined dry residues II and III were transferred to a column of Woelm polyamide (5 x 20 cm). The fractions eluted by chloroform and chloroform-ethanol (2:1) were rechromatographed on Silufol plates in the benzene-ethyl acetate (2:1) system [2]. Two individual substances were isolated: A with Rf 0.72 and B with Rf 0.36. When the column was washed further with chloroform-acetone (7:3), the fractions contained a substance C with Rf 0.09 [3, 4]. The substances obtained were subjected to repeated recrystallization from methanol.
7 citations
TL;DR: A new xanthone was isolated from the trunk wood of Haploclatha leiantha and its structure determined by UV, IR and mass spectrometry as 1,3-dihydroxy-5,6-dimethoxyxanthone as mentioned in this paper.
7 citations
TL;DR: In this paper, the emission spectra of low molecular ketones (benzophenone, 9-anthrone, 9,10-anthraquinone, xanthone and thioxanthone) in polymeric matrices, namely polyethylene (PE), isotactic polypropylene (iPP), atactic polypolypropylene(aPP), polystyrene (PS) and poly(methyl methacrylate) (PMMA), exhibit the same main features as in non-polar and polar glasses of high molecular solvents at 77 K.
5 citations
Patent•
09 Sep 1986
TL;DR: In this paper, a molding obtd. by molding a PVA/xanthone blend composed of not more than 50 pts. xanthone and 100 pts. PVA into the desired shape is immersed in an aq. soln. for 1-24hr.
Abstract: PURPOSE:To obtain the title blend having excellent resistance to acids and hot water, by treating a PVA/xantone blend with a carbamoylating agent. CONSTITUTION:A molding obtd. by molding a PVA/xanthone blend composed of not more than 50 pts.wt. xanthone and 100 pts.wt. PVA into the desired shape is immersed in an aq. soln. of a carbamoylating agent such as a monofunctional (iso)cyanic acid (salt) or a compd. capable of forming a monofunctional isocyanic acid by heating, such as urea, biuret or triuret. Optionaly, methanol is added thereto and the mixture is reacted at 0-10 deg.C for 1-24hr.
TL;DR: Xanthone and 1-hydroxyxanthone polymers were prepared by the Kostanecki reaction on salicylic acid-formaldehyde and 4-(amino, chloro, and bromo)-salicylic ac-fentaldehyde polymers, respectively, with phenol and resorcinol as discussed by the authors.
Abstract: Xanthone and 1-hydroxyxanthone polymers were prepared by the Kostanecki reaction on salicylic acid-formaldehyde and 4-(amino, chloro, and bromo)-salicylic acid-formaldehyde polymers, respectively, with phenol and resorcinol. All the xanthone polymer samples were characterized by elemental analysis, by IR spectral study, and by TGA. Xanthone polymers were also screened for their antifungal activity against a variety of fungi.
TL;DR: In this article, Wu et al. reported that xanthone glycoside, norswerianolin, posseses a depressant activity on the central nervous system.
Abstract: Bellidifolin (XI) was first isolated from the fresh whole plant of Swertia randaiensis Hayata (Gentianaceae). Further, oleanolic acid, a constituent of this plant, reported by Wu et al, wasreinvestigated by C NMR spectroscopy, being revised into ursolic acid. Pharmacological studies on the xanthone glycoside, norswerianolin, which was previously isolated from this plant, showed that it posseses a depressant activity on the central nervous system.
TL;DR: In this paper, the Perkin reaction of p-xylylene dichloride-salicylaldehyde polymer with acetic anhydride, phenyl acetic acid, and phenoxyacetic acid was used to synthesize coumarin, xanthone, and flavone polymers.
Abstract: Coumarin, 3-phenyl, and 3-phenoxy coumarin polymers were prepared by the Perkin reaction of p-xylylene dichloride-salicylaldehyde polymer with acetic anhydride, phenyl acetic acid, and phenoxyacetic acid, respectively. The xanthone polymers were prepared by the Kostanecki reaction on p-xylylene dibromide-salicylic acid polymer with phenol or resorcinol. The flavone polymer were synthesized via chalcone intermediate from p-xylylene dichloride-o-hydroxyacetophenone polymer and benzalde-hyde. All the coumarin, xanthone, and flavone polymer samples were characterized by elemental analyses, by IR spectral studies, by TGA, and by studying their antifungal activities.