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At least 73 records · Page 4Linked to original sources
PubMed2002

Synergistic catalysis of anthrone Diels-Alder reactions.

[reaction: see text] The combination of an amine base and Lewis acid (Li+) leads to synergistic catalysis of the Diels-Alder reaction of anthrone with methyl crotonate and some other less reactive dienophiles. These cycloadditions either do not occur with the individual catalysts used separately or they are greatly accelerated by the combined catalysts. DMSO solvent allows the use of LiCl as the Lewis acid source and can provide greater control of subsequent conversion to Michael adduct.

Journal Article↗
PubMed2002

1,5-dihydroxyanthraquinones and an anthrone from roots of Rumex crispus.

From the roots of Rumex crispus, two known anthraquinones and a new one together with a new anthrone were isolated and the structures of compounds 1-4 were elucidated by spectroscopic means. The singlet oxygen generation capacity was tested with 1,3-diphenylisobenzofuran (DPBF) for compounds 1-4.

Algorithms↗
PubMed1983

Tumor promoting activity of 1,8-dihydroxy-3-methyl-9-anthrone (chrysarobin) in female SENCAR mice.

Purified 1,8-dihydroxy-3-methyl-9-anthrone or chrysarobin was found to be an effective skin tumor-promoter in SENCAR mice, although, at the dose used, it was approximately 43-fold less active than 12-O-tetradecanoylphorbol-13-acetate (TPA). When non-promoting doses of chrysarobin were applied 30 min prior to each application of TPA, a marked potentiation in the promoting response to TPA was observed. Chrysarobin will provide a valuable tool for studying the mechanism of action of anthracene-derived mouse skin tumor promoters.

Animals↗
PubMed1993

Cleavages of the O- and C-glucosyl bonds of anthrone and 10,10'-bianthrone derivatives by human intestinal bacteria.

A strictly anaerobic bacterium, Bifidobacterium sp. SEN, capable of hydrolyzing the O-glucosyl of sennosides was isolated from human feces. The bacterium stepwisely hydrolyzed sennoside B to sennidin B through sennidin-8-monoglucoside in PYF medium but not in GAM broth. Addition of D-glucose to PYF medium resulted in loss of the hydrolyzing activity in culture but addition of D-fructose did not affect the activity. Coculture of this bacterium with Peptostreptococcus intermedius led to rapid accumulation of rhein anthrone in the medium. Similarly, a bacterium, Eubacterium sp. BAR, capable of cleaving the C-glucosyl of barbaloin was isolated from human feces. This bacterium grew in PYF medium containing barbaloin and produced enzyme(s) that cleave(s) the C-glucosyl. The induction of the enzymes was completely inhibited in the presence of D-glucose. Nojirimycin inhibited the enzyme activity induced by barbaloin but it did not inhibit the bacterial growth in the presence of D-glucose.

Aloe↗
PubMed2002

Permeation-enhancing effect of aloe-emodin anthrone on water-soluble and poorly permeable compounds in rat colonic mucosa.

The aims of this study were to examine the enhancing effects of aloe-emodin anthrone (AEA) on the colonic membrane permeability of water-soluble and poorly permeable compounds and to clarify the mechanism of the permeation-enhancing activity of AEA. The permeation-enhancing activity of AEA was estimated from changes in the permeability coefficient of 5(6)-carboxyfluorescein (CF) in rat colonic mucosa using a Ussing-type chamber. Various inhibitors were used to investigate the mechanism of action of AEA. The structural change in the membrane and the cytotoxicity of AEA in the intestinal mucosa were evaluated by measuring the electrical resistance of the membrane (R(m)) and lactate dehydrogenase (LDH) activity, respectively. AEA significantly increased the permeation of CF in a dose-dependent manner. The enhanced permeability was significantly suppressed by a histamine H(1) receptor antagonist, pyrilamine, and a mast cell stabilizer, ketotifen, but not by a histamine H(2) receptor antagonist, cimetidine. The enhancing effect was also inhibited by an inhibitor of protein kinase C (PKC). Potential difference and short-circuit current values decreased, while R(m) values remained constant throughout the experiment. The addition of AEA to the mucosal solution decreased R(m) to 30%, but then remained constant. LDH activity with AEA was not significantly different from that of the control. In conclusion, AEA is a candidate for effective absorption enhancers without damage of the membrane and cytotoxicity. We propose that AEA stimulates mast cells within the colonic mucosa to release histamine, which probably bind to the H(1) receptor. The intracellular PKC route activated by H(1) receptor activation enhances the permeability of water-soluble and poorly permeable drugs via opening of tight junctions in rat colonic membrane.

Animals↗
PubMedDate not supplied

Isolation of chrysophanic acid-9-anthrone, the major antifungal principle of Cassia tora.

An antifungal principle of defatted seed power of Cassia tora Linn. was isolated by extraction of an aqueous paste of the powder with benzene, followed by column chromatography over activated silica gel C using chloroform as the developing solvent. Besides chrysophanic acid and other hydroxyanthraquinone derivatives, the major antifungal compound was identified as chrysophanic acid-9-anthrone, the structure of which was assigned on the basis of its chemical properties and uv, ir, nmr and mass spectral analysis. The compound was active against Trichophyton rubrum, T. mentagrophytes, Microsporum canis, M. gypseum and Geotrichum candidum in broth in the presence of 100 mug/ml L-ascorbic acid as antioxidant.

Anthracenes↗