Showing papers on "Xanthone published in 1983"
TL;DR: In this paper, the aplicability of the Fo¯rster cycle to xanthone is discussed and a quenching technique may be used to differentiate below two normally indistinguishable sets of kinetic circumstances: when dissociation of the conjugate acid is observable and when it is not.
16 citations
TL;DR: In this article, the magnetic field effect on the hydrogen abstraction of xanthone from xanthene in SDS aqueous micellar solutions was studied using laser flash photolysis.
15 citations
Patent•
16 May 1983
TL;DR: In this article, a process for extracting xanthone glycosides from the aerial portion of the plants by means of a mixture acetone-water at a volume ratio of the mixture components of 1:0.5-2 respectively is described.
Abstract: A process for preparing mangiferin from plants of the genus of Hedysarum (Hedysarum alpinum L., Hedysarum flavescens Rgl. et Schmalh) comprising extraction of xanthone glycosides from the aerial portion of the plants by means of a mixture acetone-water at a volume ratio of the mixture components of 1:0.5-2 respectively; the resulting extract is evaporated, the evaporated extract is filtered. To the filtered evaporated extract sulphuric acid is added to a pH of from 2 to 4, heated at reflux and filtered. The thus-prepared extract is treated with a non-polar organic solvent with the formation of two layers, wherefrom the upper aqueous layer contains xanthone glycosides. This upper layer is treated with butanol with the formation of two layers, wherefrom the upper layer comprises a solution of xanthone glycosides in butanol. This upper butanolic layer is evaporated. The precipitated mangiferin is separated and recrystallized.
8 citations
TL;DR: In this paper, the petrol and methanol extracts of the bark and timber of Garcinia thwaitesii have been investigated and β-amyrin and tirucallol, four biflavonoids and a new xanthone, 2,5-dihydroxy-1,6-dimethoxyxanthone have been isolated and characterized.
7 citations
Journal Article•
TL;DR: Xanthone-2-carboxylic acids 4a-4k were synthesized as potential antiphlogistic compounds, and compounds 4a -4c and 4f-4i were tested for anti-inflammatory and analgesic properties.
Abstract: Xanthone-2-carboxylic acids 4a-4k were synthesized as potential antiphlogistic compounds, and compounds 4a-4c and 4f-4i were tested for anti-inflammatory and analgesic properties. In the carrageenin paw edema the most potent of the series acid 4b displayed the activity which was approx one third of that of ketoprofen.
4 citations
TL;DR: In a study of the fruit of AngeZoa komayou collected in the valley of the R. Oital close to the village of Aktob (0shsk province, KirgSSR), this article found a considerable amount of coumarins in it.
Abstract: In a study of the fruit of AngeZ~oa komayou~ collected in the valley of the R. Oital close to the village of Aktob (0shsk province, KirgSSR), we found a considerable amount of coumarins in it. By extraction with ethanol and absorption chromatography on silica gel with elutlon by benzene and mixtures of benzene and ethyl acetate with gradually increasing proportions of the latter, we isolated three crystalline compounds possessing the properties of coumarins: (I) C=~HsoOs, mp 61-63°C; (II) C~TH~,O~, mp I0i-102°C~ (III)CI,H,a07, mp i17-i18°C. On the basis of their physicochemical constants and their UV, IR, and PMR spectra, substances (1)-(Ill) have been identified as, respectively, umbelliprenin, phellopterin, and biacangelicin.
3 citations