Showing papers on "Xanthone published in 1984"
51 citations
TL;DR: In this paper, two new xanthones, 1,5-dihydroxy-6′,6′-dimethyl-2H-pyrano(2′,3′:3,2)-6″,6″-dimethylamine 2H pyranojacareubin (2″,3″:6,7)xanthone and 1.5,6-trihydroxy-1.5-methylprop-2-enyl (1.8-deoxygartanin), were isolated from the roots
40 citations
28 citations
TL;DR: Xanthine oxidase (XO) inhibitor was isolated from the aerial parts of Athylium mesosorum MAKINO (Aspidiaceae) and was identified as norathyriol (1, 3, 6, 7-tetrahydroxyxanthone) (1).
Abstract: Xanthine oxidase (XO) inhibitor was isolated from the aerial parts of Athylium mesosorum MAKINO (Aspidiaceae) and was identified as norathyriol (1, 3, 6, 7-tetrahydroxyxanthone) (1). The type of inhibition by 1 with respect to xanthine as a substrate was uncompetitive. The inhibitory activities of related xanthone derivatives towards XO were assayed.
27 citations
TL;DR: A new xanthone was isolated from the heartwood of Mesua ferrea and its structure determined by UV, IR, NMR and mass spectrometry as 1,3-dimethoxy-5,6-dihydroxyxanthone as mentioned in this paper.
24 citations
TL;DR: The oxa-di-π-methane rearrangement product 4,4,9,9-tetramethyltetracyclo [6.02,8]dodecane-7,12-dione (2) is formed selectively in a variety of solvents on either direct (λLD = 254, 300, 350 nm) or sensitized (xanthone, acetone, benzene) irradiation of the title compound 1.4.0.
Abstract: The oxa-di-π-methane rearrangement product 4,4,9,9-tetramethyltetracyclo [6.4.0.01,5.02,8]dodecane-7,12-dione (2) is formed selectively in a variety of solvents on either direct (λLD = 254, 300, 350 nm) or sensitized (xanthone, acetone, benzene) irradiation of the title compound 1. The efficiency for this rearrangement is higher on So–S1 excitation (Φ−1 = 0.67) than on either So–S2 or So–S3 excitation (Φ−1 = 0.58).
5 citations
TL;DR: In this article, the reaction of l,3-dihydroxy-6-methoxy- and 1,3,6-trihydroxy-xanthone with 1-bromo3-methylbut-2-ene in presence of methanolic sodium methoxide, to give corresponding 3-methyl but-2enylated xanthones, is described.
5 citations
TL;DR: In this paper, the yields of escaping ketyl radicals from the radical pairs formed through the reactions of triethylgermane with the triplet states of acetophenone and xanthone were found to be increased by a magnetic field.
Abstract: The yields of the escaping ketyl radicals from the radical pairs formed through the reactions of triethylgermane with the triplet states of acetophenone and xanthone were found to be increased by a magnetic field. The observed increases at 1 T were 3 and 27% for the ketyl radicals of acetophenone and xanthone, respectively.
4 citations
TL;DR: In this paper, the ozonation of xanthydrol was studied using an oxygen stream, which gave singlet oxygen, water and xanthone accompanied by autoxidation.
Abstract: The ozonation of xanthene was studied using an oxygen stream. Ozone attacks the methylene group of xanthene via a 1,3-dipolar insertion reaction to give the hydrotrioxide intermediate, followed by a loss of singlet oxygen to form xanthydrol. The ozonation of xanthydrol gave singlet oxygen, water and xanthone accompanied by autoxidation.
2 citations
TL;DR: In this paper, the authors discuss the effect of the altitude on the performance of SDS and propose a method to mitigate the impact of altitude on SDS in the following manner:
Abstract: ドデシル硫酸ナトリウム(SDS)ミセル溶液中のキサントンの水素引き抜き反応の外部磁場効果を定常光法(≦260mT),レーザーせん光法(≦80mT)により研究した。ミセル中のキサントンは光照射により徐々に界面活性剤から水素を引き抜く。この溶液にキサンテンを加えると,キサンテンからの水素引き抜き反応が効率よく起こる。キサントンの消失の相対量子収量,9-キサンテニルラジカル反応中間体の過渡吸収,生成物の収量に顕著な外部磁場効果が観測され,このことはCIDNPのラジカル対モデルにより説明された。