Showing papers on "Xanthone published in 1980"
309 citations
TL;DR: Psorospermin 1 was demonstrated to have significant antitumor activity in the P388 in vivo system as well as cytotoxicity against the KB in vitro system.
Abstract: An ethanolic extract of Psorospermum febrifugum was fractionated with antileukemic activity in vivo in the P388 lymphocytic leukemia in mice and in vitro in the KB cell culture system used as a guide. The new antileukemic xanthone psorospermin 1 was isolated, and its structure was elucidated. The chlorohydrin of O-methylpsorospermin 2 was also isolated after treatment of the fraction containing psorospermin chlorohydrin 6 with diazomethane. Psorospermin 1 was demonstrated to have significant antitumor activity in the P388 in vivo system as well as cytotoxicity against the KB in vitro system.
101 citations
Journal Article•
55 citations
51 citations
TL;DR: The stem bark of a species of Garcinia (Guttiferae), provisionally identified as G. densivenia, has yielded a xanthone and two biflavonoids as discussed by the authors.
39 citations
TL;DR: Three new oxaphenalenone dimers, bacillosporins A-C, and one known xanthone carboxylic acid, pinselin, were isolated from a fungus, Talaromyces bacilloides as mentioned in this paper.
Abstract: Three new oxaphenalenone dimers, bacillosporins A-C, and one known xanthone carboxylic acid, pinselin, were isolated from a fungus, Talaromyces bacillosporus. Bacillosporin A (1) is an acetyl derivative of B (2). Bacillosporin A was transformed to xenoclauxin (5), a known oxaphenalenone dimer, by 2, 3-dichloro-5, 6-dicyanobenzoquinone (DDQ) oxidation. The hemiketal structure of bacillosporin C (7) was proposed on the basis of the spectral data for the compound itself and the hydrogenolysis product (9).
37 citations
TL;DR: An investigation of the stem bark of Garcinia ovalifolia oliv. (Guttiferae) has revealed the presence of large quantities of the polyisoprenyl benzophenone xanthochymol as mentioned in this paper.
Abstract: An investigation of the stem bark of Garcinia ovalifolia oliv. (Guttiferae) has revealed the presence of large quantities of the polyisoprenyl benzophenone xanthochymol. Isoxanthochymol was identified as a minor component. In addition the bark yielded small amounts of a tetraoxygenated xanthone which was shown to be identical with the known compound macluraxanthone, otherwise found only in the Moraceae. The common triterpenes friedelin and sitosterol were also present. The biological significance of these findings is briefly discussed.
22 citations
TL;DR: Results show that the aglycone of 1 and 2 was biosynthesized from p-coumarate (C6-C3) and two malonates (C4), and doubly labelled p- coumaric acid was incorporated into 1 without change of the T/14C ratio.
Abstract: Phenylalanine-1-14C, -2-14C and -3-14C, and malonic acid-2-14C were efficiently incorporated into mangiferin (1) in Anemarrhena asphodeloides. In the case of feeding with phenylalanine-1-14C, -2-14C and malonic acid-2-14C, the radioactivity of 1 was localized in the phloroglucinol ring. Furthermore, cinnamic acid-3-14C and p-coumaric acid-2-14C were also incorporated into 1 and isomangiferin (2), but benzoic acid-, p-hydroxybenzoic acid-and protocatechuic acid-(carboxyl-14C) were essentially not incorporated into 1 or 2. In addition to the above data, doubly labelled p-coumaric acid was incorporated into 1 without change of the T/14C ratio. These results show that the aglycone of 1 and 2 was biosynthesized from p-coumarate (C6-C3) and two malonates (C4).
22 citations
TL;DR: The whole plant of Swertia hookeri has been shown to contain two tri- and nine tetraoxygenated free, glucosyloxy, and stearyl ester xanthones and one flavonol stearylene ester, among which three were previously unreported in nature and one was known previously only as a synthetic compound.
21 citations
TL;DR: A new xanthone-O -glycoside isolated from the fern Asplenuim adiantum-nigrum has been identified as 3,7,8- trihydroxyxanthone -1- O -β-laminaribioside by chemical and spectroscopic methods as discussed by the authors.
12 citations
TL;DR: Results indicate that C-glucosylation of 1 and 2 occurs at the stage of maclurin (3), prior to the formation of the xanthone nucleus, and that 1 and 1 may be biosynthesized via 3-C-glUCosylmaclur in (6).
Abstract: A benzophenone, maclurin-1, 3, 5-14C3 (3), was efficiently incorporated into C-glucosylxanthones [mangiferin (1) and isomangiferin (2)] of Anemarrhena asphodeloides without randomization, but the labelled aglycone of 1 and 2 (1, 3, 6, 7-tetrahydroxyxanthone-2, 4, 9a-14C3) (4) was essentially not incorporated. Furthermore, the incorporation of phenylalanine-3-14C into 1 and 2 was clearly suppressed by the addition of non-labelled maclurin (3) to the precursor solution. These results indicate that C-glucosylation of 1 and 2 occurs at the stage of maclurin (3), prior to the formation of the xanthone nucleus, and that 1 and 2 may be biosynthesized via 3-C-glucosylmaclurin (6). A biosynthetic route is proposed for mangiferin (1) and related C-glucosylxanthones.
TL;DR: A re-consideration of the 1H n.m.r. data for toxyloxanthone B trimethyl ether and an unambiguous total synthesis both show that the 1,1-dimethylpyrano[3,2-a]xanthone structure has the same structure as mentioned in this paper.
Abstract: A re-consideration of the 1H n.m.r. data for toxyloxanthone B trimethyl ether and an unambiguous total synthesis both show that toxyloxanthone B has the 1,1-dimethylpyrano[3,2-a]xanthone structure (1a) and not the 3,3dimethylpyrano[3,2-a]xanthone system (2) previously assigned. The synthesis is based on the preparation of 1,7-dihydroxy-3,5-dimethoxyxanthone (5) from cyclisation of a benzophenone precursor (3a) or (3b) and selective demethylations. A Claisen rearrangement of the 7-prop-2-ynyloxyxanthone (6) followed by cyclisation and methylation gives toxyloxanthone B trimethyl ether.
TL;DR: In this paper, a heat-pulse modulation technique has been applied to the phosphorescence study of xanthone in n -pentane at 1.5 and 4.2 K.
01 Jan 1980