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Showing papers on "Xanthone published in 1996"


Journal ArticleDOI
TL;DR: In this article, the effect of alcohol addition on the ground state complexation of xanthone with cyclodextrins and on the dissociation rate constants of triplet Xanthone from these complexes was studied by fluorescence and laser flash photolysis experiments.
Abstract: The effect of alcohol addition on the ground state complexation of xanthone with cyclodextrins (CDs) and on the dissociation rate constants of triplet xanthone from these complexes was studied by fluorescence and laser flash photolysis experiments. In the case of β- and Hp-β-CD, the addition of alcohol led to the formation of weaker ternary complexes when compared to the xanthone CD binary complexes. In contrast, for γ-CD a slight increase of the complexation strength was observed for the ternary complexes. Addition of alcohols decreased the dissociation rate constant of triplet xanthone from β- and γ-CD by at least a factor of 5. The fact that the dissociation processes was slowed down for both CDs suggests that the effect of ternary complexation agents on the dynamics of complexation was not related to the strength of the ternary complexes formed.

107 citations


Journal ArticleDOI
TL;DR: In this paper, a new polyoxygenated xanthone mangostanol was isolated from the fruit hull of Garcinia mangostana, along with known xanthones, α-mangostin, γ-mengostin and gartanin, 8-deoxygartnin, 5,9-dihydroxy-2,2-dimethyl-8-methoxy-7-(3-methylbut-2-enyl)-2 H,6 H -pyrano[3, 2-b ]xanthen

85 citations


Journal ArticleDOI
TL;DR: In this article, excited triplet naphthalene and xanthone were employed as probe molecules to study the dynamics of incorporation into sodium cholate, taurocholate, and deoxycholate aggregates.
Abstract: Excited triplet naphthalene and xanthone were employed as probe molecules to study the dynamics of incorporation into sodium cholate, taurocholate, and deoxycholate aggregates. The association and dissociation rate constants and the quenching rate constants for the incorporated probes were recovered from the dependence of the observed triplet decay rate constants on quencher concentrations (nitrite and cupric ions). Triplet naphthalene was incorporated into a site offering a high degree of protection from quenchers and from which dissociation was relatively slow. Triplet xanthone was incorporated into a less protected site from which dissociation was an order of magnitude faster than from the naphthalene site. We propose that naphthalene was incorporated into the hydrophobic site of primary aggregates, and xanthone was located in the region containing the hydroxyl groups in the secondary aggregates.

60 citations


Asai, Fujio, Tosa, Hideki, Tanaka, Toshiyuki, Iinuma, Munekazu 
30 Jun 1996

54 citations


Journal ArticleDOI
TL;DR: Garciaxanthone E is the second geranylated xanthone isolated from Garcinia species as mentioned in this paper, along with the previously known symphoxanthone and subelliptenone A from the wood of Garcinia sub-elliptica.

41 citations


Journal ArticleDOI
TL;DR: Structural elucidation indicated that xanthoquinodin B3 has the same heterodimer of xanthone- and anthraquinone-derived monomers as other xanthOquinodins, which was detected in the culture broth of Humicola sp.
Abstract: Xanthoquinodin B3, a new component of anticoccidial xanthoquinodins, which was detected in the culture broth of Humicola sp. FO-888, was isolated by heat treatment of the xanthoquinodins complex. Structural elucidation indicated that xanthoquinodin B3 has the same heterodimer of xanthone- and anthraquinone-derived monomers as other xanthoquinodins. Schizont formation of monensin-resistant Eimeria tenella in BHK-21 cells was inhibited by xanthoquinodin B3 at concentrations greater than 0.035 microM.

32 citations


Journal ArticleDOI
TL;DR: Secologanoside is reported here for the first time in Gentianaceae species; the antioxidant mangiferin was obtained as the major compound in good yield.
Abstract: From Gentianella nitida twelve known metabolites were isolated and identified by HPLC-UV and/or by spectroscopic methods as secologanoside, amaroswerin, amarogentin (secoiridoids), isoorientin (C-glucosylflavone), mangiferin, demethylbellidifolin 8-O-glucoside, norswertianine 1-O-glucoside, swertianine 1-O-primeveroside, swertianine 8-O-glucoside, norswertianine, demethylbellidifolin, and swertianine (xanthone glycosides and aglycones). Secologanoside is reported here for the first time in Gentianaceae species ; the antioxidant mangiferin was obtained as the major compound in good yield.

27 citations


Journal ArticleDOI
TL;DR: In this paper, the chemical constituents of the roots of Garcinia dulcis are investigated and three new benzophenone-xanthone dimers named garciduols A-C (1-3) are identified.
Abstract: Investigation of the chemical constituents of the roots of Garcinia dulcis resulted in the isolation of three new benzophenone-xanthone dimers named garciduols A-C (1-3) in addition to a new xanthone, 1,3,6-trihydroxy-7-methoxyxanthone (4). Five known xanthones [2,5-dihydroxy-1-methoxy- (5), 1,4,5-trihydroxy- (6), 1,3,5-trihydroxy-(7), 1,3,6-trihydroxy-5-methoxy- (8) and 1,3,6-trihydroxy-8-isoprenyl-7-methoxyxanthone (9)] were also isolated from the roots. Their structures were determined by spectroscopic analysis including two dimensional NMR. The behaviors of chemical shifts caused by acetylation and the position of the methoxyl group in the dimers characterized by model synthetic benzophenones are also discussed.

26 citations


Journal ArticleDOI
TL;DR: The structure of the new compound has been defined by means of FAB-mass spectrometry and a combination of homo- and hetero-nuclear one- and two-dimensional NMR techniques.

25 citations


Journal ArticleDOI
TL;DR: In this article, three new xanthones were isolated from the bark of Garcinia dioica (Guttiferae) in addition to a known xanthone, 1, 3, 6-trihydroxy-8-geranyl-7-methoxyxanthone (rubraxanthone).
Abstract: Three new xanthones were isolated from the bark of Garcinia dioica (Guttiferae) in addition to a known xanthone, 1, 3, 6-trihydroxy-8-geranyl-7-methoxyxanthone (rubraxanthone). The structures of the three xanthones were elucidated to be 1, 3, 6-trihydroxy-8-(7-hydroxy-3, 7-dimethyl-2, 5-octadieyl)-7-methoxyxanthone, 1, 3, 6-trihydroxy-8-(6, 7-epoxy-3, 7-dimethyl-2-octenyl)-7-methoxyxanthone and 1, 3, 7-trihydroxy-2, 4-diisoprenylxanthone by the aid of spectroscopic analysis including the two dimensional NMR technique. The occurrence of xanthone with such a C10 alkyl chain is rare in naturally occurring compounds.

20 citations


Journal ArticleDOI
TL;DR: In this paper, the incorporation of 18O-labeled molecular oxygen in the biosynthesis of aflatoxin B1 is reported and allows a minimal mechanism to be proposed where a monooxygenase activation of the xanthone is followed by a dioxygenase-mediated aryl cleavage to initiate the final rearrangement and decarboxylation to the mycotoxin.
Abstract: The final steps in the biosynthesis of the potent environmental carcinogen aflatoxin B1 (7) involve the oxidative cleavage of the xanthone O-methylsterigmatocystin (6, R = Me) and rearrangement to the substituted coumarin skeleton of the mycotoxin itself. This process has been determined to require loss of a xanthone nuclear carbon at the oxidation state of carbon dioxide and argues for the intervention of at least two oxidative reactions in this poorly understood transformation. The incorporation of 18O-labeled molecular oxygen in the biosynthesis of aflatoxin B1 is reported and allows a minimal mechanism to be proposed where a monooxygenase activation of the xanthone is followed by a dioxygenase-mediated aryl cleavage to initiate the final rearrangement and decarboxylation to aflatoxin B1. Similarly, two other sites of heavy oxygen incorporation are consistent with proposed Baeyer−Villiger-like reactions taking place earlier in the pathway.

Journal ArticleDOI
TL;DR: Hydperoxides in general quench type I-sensitized (benzophenone, xanthone) photo-oxidation of guanine, but not that of rose bengal, a predominant type II sensitizer.
Abstract: Xanthone-sensitized photo-oxidation of guanine in calf thymus DNA and in the nucleoside 2′-deoxyguanosine has been investigated in the presence of various additives, with major emphasis on hydroperoxides. The formation of the guanine oxidation products 7,8-dihydro-8-oxoguanine (8-oxoGua), which is a marker for oxidative DNA damage, and 2,2,- diamino -4-[(2- deoxy -β- d -erythro- pentoffuranosyl )amino]-5(2H)- oxazolone (oxalonone) was monitored quantitatively by high performance loquid chromatography electrochemical or fluorescence analysis. Irradiation (350 nm) of calf thymus DNA in the presence of xanthone as sensitizer afforded 8-oxoGua in 1.4% yield. The ethyl oleate hydroperoxide 1a and it alcohol 1b inibiit the formation of 8-oxoGua very efficiently (up to 85%). Even the structurally simple t-butyl hydroperoxide and the physiologically relevant hydrogen peroxide exhibit strong inhibition f photosensitized oxidation of guanine in DNA and in the nucleoside, while t-butanol and the allylic alcohols 3b and 4 do not. Hydroperoxids in general quench type I-sensitized (benzophenone, xanthone) photo-oxidation of guanine, but not that of rose bengal, a predominant type II sensitizer. The inhibiting effect is explained by H abstraction of the electronically excited carbonyl chromophore from the additive. The biological relevance of these findings should be seen in the potential protecting role of lipid hydroperoxides and their corresponding alcohols against oxidative stress.

Journal ArticleDOI
TL;DR: The He I photoelectron spectra of xanthone, thioxanthone and acridone have been measured and comparatively discussed on the basis of the HMO, MINDO/3, MNDO, and PM3 methods as discussed by the authors.

Journal Article
TL;DR: A series of xanthone-1,4-dihydrophyridine derivatives bearing a chlorine atom in the Xanthone nucleus were developed in this article for inotropic, chronotropic and calcium antagonist properties.
Abstract: A series of xanthone-1,4-dihydrophyridine derivatives bearing a chlorine atom in the xanthone nucleus was prepared. The compounds were evaluated for inotropic, chronotropic and calcium antagonist properties. The chlorine introduction in the xanthone moiety slightly affected affinity for cardiac vs. vascular tissues improving to some extent selectivity.

Journal ArticleDOI
TL;DR: In this article, the photochemistry of methyl 2-phenoxybenzohydroxamate was studied and it was found that the relative amounts of the type II product and the phenyl migration product were solvent dependent.
Abstract: The photochemistry of methyl-2-phenoxybenzohydroxamate was studied. This compound was found to undergo the type I reaction followed by intramolecular cyclization to generate xanthone, the type II reaction to generate 2-phenoxybenzamide, and a formal 1,5 shift of the phenyl group from the benzohydroxamate ring to the nitrogen. It was also found that the relative amounts of the type II product and the phenyl migration product were solvent dependent. Photolysis in methanol favored the phenyl migration process whereas photolysis in cyclohexane favored the type II process. These results are attributed to an increased amount of single electron transfer from the phenoxy group to the carbonyl group relative to the type II process in methanol. The photolysis of N,N-dimethyl-2-phenoxybenzamide, which cannot undergo phenyl migration, gives xanthone as the only product.

Journal ArticleDOI
TL;DR: The study of isolated sarcoplasmic reticulum vesicles from rabbit skeletal muscle suggests that xanthone and norathyriol can induce Ca2+ release from the SR of skeletal muscle through a direct interaction with the Ca2- release channel, also known as the ryanodine receptor.
Abstract: 1. Effects of xanthone and its derivative, 1,3,6,7-tetrahydroxyxanthone (norathyriol), on Ca2+ release and ryanodine binding were studied in isolated sarcoplasmic reticulum (SR) vesicles from rabbit skeletal muscle. 2. Both xanthone and norathyriol dose-dependently induced Ca2+ release from the actively loaded SR vesicles which was blocked by ruthenium red, a specific Ca2+ release inhibitor, and Mg2+. 3. Xanthone and norathyriol also dose-dependently increased apparent [3H]-ryanodine binding. Norathyriol, but not xanthone, produced a synergistic effect on binding activation when added concurrently with caffeine. 4. In the presence of Mg2+, which inhibits ryanodine binding, both caffeine and norathyriol, but not xanthone, could restore the binding to the level observed in the absence of Mg2+. 5. Xanthone activated the Ca(2+)-ATPase activity of isolated SR vesicles dose-dependently reaching 70% activation at 300 microM. 6. When tested in mouse diaphragm, norathyriol potentiated the muscle contraction followed by twitch depression and contracture in either a Ca(2+) -free bathing solution or one containing 2.5 mM Ca2+. These norathyriol-induced effects on muscle were inhibited by pretreatment with ruthenium red or ryanodine. 7. These data suggest that xanthone and norathyriol can induce Ca2+ release from the SR of skeletal muscle through a direct interaction with the Ca2+ release channel, also known as the ryanodine receptor.



Journal ArticleDOI
Abstract: The X-ray crystal structures of three crown ethers containing the 1,8-dioxyxanthone residue are reported. 1,8-[(3,6,9-Trioxaundecane-1,11-diyl)dioxy]xanthone, 1(n= 3), and 1,8-[(3,6,9,12,15-pentaoxaheptadecane-1,17-diyl)dioxy]xanthone, 1 (n= 5), have been crystallized from acetonitrile and their crystals shown to incorporate acetonitrile. Crystals of the former also contain water which forms a tight hydrogen-bonded bridge between the xanthone carbonyl oxygen and the most remote oxygen of the 18-membered macrocycles. Crystals of 1,8-[(3,6,9,12-tetraoxatetradecane-1,14-diyl)dioxy]xanthone, 1 (n= 4), from toluene do not incorporate solvent molecules.Earlier UV measurements for the basicity of the carbonyl oxygen for these crowns and for 1,8-diethoxyxanthone have been re-examined using the excess acidity method and revised values of pKa and m* are reported. The UV spectra of methanolic solutions of the ketones show shifts with added strontium or barium salts and these are associated with complex formation which places the metal ion in close proximity to the carbonyl oxygen. Binding constants for formation of complexes are reported.



Journal Article
TL;DR: A series of xanthone and fluorenone-1,4-dihydropyridine derivatives bearing a 5-phosphonate group were prepared and evaluated for inotropic, chronotropic and calcium antagonistic properties as mentioned in this paper.
Abstract: A series of xanthone and fluorenone-1,4-dihydropyridine derivatives bearing a 5-phosphonate group were prepared. The compounds were evaluated for inotropic, chronotropic and calcium antagonistic properties. The insertion of a phosphonate group is detrimental for inotropic and calcium antagonistic activity but improves the potency and selectivity for chronotropism.

Journal ArticleDOI
TL;DR: In this article, a new p-hydroxybenzoylated xanthone, [ 2-(2′-O-p- hydroxy benzoyl) -C-β-d -glucopyranosyl-1,3,6,7-tetrahydroxyxanthone ], muraxanthone and four known xanthones have been isolated from the leaves of Senecio mikanioides.
Abstract: A new p-hydroxybenzoylated xanthone, [ 2-(2′-O-p- hydroxybenzoyl) -C-β- d -glucopyranosyl-1,3,6,7-tetrahydroxyxanthone ], muraxanthone, and four known xanthones have been isolated from the leaves of Senecio mikanioides. The structure of the new compound has been defined by means of FAB-mass spectrometry and a combination of homo- and hetero-nuclear one- and two-dimensional NMR techniques.

Journal ArticleDOI
TL;DR: The introduction of a 2,3-lactone ring improved the negative inotropic activity and selectivity of xanthone 1,4-dihydropyridine derivatives.
Abstract: A series of xanthone 1,4-dihydropyridine derivatives bearing a 2,3-lactone ring and a 2-acetoxymethyl group were prepared. The compounds were evaluated for inotropic, chronotropic and calcium antagonist properties. The introduction of a 2,3-lactone ring improved the negative inotropic activity and selectivity.

Journal ArticleDOI
TL;DR: Xanthoquinodin B3, a new component of anticoccidial xantho-quinodins, which was detected in the culture broth of Humicola sp. FO-888, was isolated by heat treatment of the xanthone-and anthraquinone-derived monomers as mentioned in this paper.
Abstract: Xanthoquinodin B3, a new component of anticoccidial xanthoquinodins, which was detected in the culture broth of Humicola sp. FO-888, was isolated by heat treatment of the xanthoquinodins complex. Structural elucidation indicated that xanthoquinodin B3 has the same heterodimer of xanthone- and anthraquinone-derived monomers as other xanthoquinodins. Schizont formation of monensin-resistant Eimeria tenella in BHK-21 cells was inhibited by xanthoquinodin B3 at concentrations greater than 0.035 microM.

Patent
30 Jul 1996
TL;DR: In this paper, an active oxygen eliminating agent containing 1, as active ingredient, a new exanthone compound extracted from Garcinia-subelliptica, excellent in lipoperoxide-inhibitory action, free radical-eliminating action and superoxide elimination.
Abstract: PURPOSE: To obtain an active oxygen eliminating agent containing, as active ingredient, a new exanthone compound extracted from Garcinia-subelliptica, excellent in lipoperoxide-inhibitory action, free radical-eliminating action and superoxide-eliminating action, thus useful for preventing/treating various diseases due to an excess of active oxygen CONSTITUTION: This active oxygen-eliminating agent contains, as active ingredient, 1,4,5-trihydroxyxanthone of formula I, or a xanthone compound of formula II, III or IV The above xanthone compound is obtained by grinding a dried material of Garcinia-subelliptica belonging to Hypericum plant and subjecting the resultant dry powder to extraction with an organic solvent such as methanol or ethanol followed by isolation by column chromatography using a carrier such as silica gel

Journal ArticleDOI
TL;DR: The insertion of a phosphonate group is detrimental for inotropic and calcium antagonistic activity but improves the potency and selectivity for chronotropism.
Abstract: A series of xanthone and fluorenone-1,4-dihydropyridine derivatives bearing a 5-phosphonate group were prepared. The compounds were evaluated for inotropic, chronotropic and calcium antagonistic properties. The insertion of a phosphonate group is detrimental for inotropic and calcium antagonistic activity but improves the potency and selectivity for chronotropism.