- PET imaging of nobiletin based on a practical total synthesis
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A practical synthesis of nobiletin, a polymethoxylated citrus flavone, was accomplished by utilizing our novel flavone synthesis. Synthetic nobiletin was labelled by selective demethylation and rapid incorporation of 11C atom. Positron emission tomography images successfully visualized the brain distribution, which may provide therapeutic benefits in the treatment of Alzheimer's disease. The Royal Society of Chemistry.
- Asakawa, Tomohiro,Hiza, Aiki,Nakayama, Miho,Inai, Makoto,Oyama, Dai,Koide, Hiroyuki,Shimizu, Kosuke,Wakimoto, Toshiyuki,Harada, Norihiro,Tsukada, Hideo,Oku, Naoto,Kan, Toshiyuki
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p. 2868 - 2870
(2011/04/22)
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- Miscrowave-assisted efficient synthesis of polymethoxyacetophenones and natural polymethoxyflavones, and thier inhibitory effects on melanogenesis
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Microwave, assisted Friedel-Crafts acetylation of polymethoxybenzenes with acetic anhydride in the presence of In(CF3SO3)3 under solvent-free conditions was achieved rapidly to give polymethoxyacetophenones in high yields. Microwave-assisted benzoylation of 2'-hydroxypolymethoxyacetophenones with polymethoxybenzoyl chlorides, followed by the rearrangement of the resulting benzoates and the final formation of natural polymethoxyflavones was achieved rapidly and efficiently. The polymethoxyflavones showed inhibitory effects on melanogenesis in human melanoma cells.
- Tsukayama, Masao,Kusunoki, Eiji,Hossain, Mohammad M.,Kawamura, Yasuhiko,Hayashi, Shinji
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p. 1589 - 1600
(2008/09/17)
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- Improved, rapid and efficient synthesis of polymethoxyflavones under microwave irradiation and their inhibitory effects on melanogenesis
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The microwave-assisted methylation of 2,5-dihydroxy-1,3-dimethoxybenzene with (CH3O)2SO2 for 5 min gave easily 1,2,3,5-tetramethoxybenzene, which was converted into pentamethoxybenzene. The microwave-assisted Friedel-Crafts acylation of pentamethoxybenzene in the presence of In(CF3SO3)3 gave pentamethoxyacetophenone for 15 min under solvent-free conditions in high yield. The microwave-assisted cyclization reaction of the diketones, which were synthesized from the acetophenone via three steps under microwave irradiation, gave the desired polymethoxyflavones for 1.5-3 min in high yields. The polymethoxyflavones showed inhibitory effects on melanogenesis in a human melanoma.
- Tsukayama, Masao,Kawamura, Yasuhiko,Ishizuka, Takaaki,Hayashi, Shinji,Torii, Fumihito
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p. 2775 - 2784
(2007/10/03)
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- STUDIES OF THE SELECTIVE O-ALKYLATION AND DEALKYLATION OF FLAVONOIDS. IX. A NEW METHOD FOR SYNTHESIZING 3,5-DIHYDROXY-7,8-DIMETHOXYFLAVONES FROM 3-HYDROXY-5,7,8-TRIMETHOXYFLAVONES
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2-Hydroxy-3,4,6-trimethoxy-ο-(p-methoxybenzoyloxy)acetophenone was prepared fom 2,3,4,6-tetramethoxyacetophenone via the corresponding ο-bromoacetophenone.Cyclization of the acetophenone with p-methoxybenzoic anhydride by application of the Allan-Robinson
- Horie, Tokunaru,Tsukayama, Masao,Kawamura, Yasuhiko,Yamamoto, Shigeo
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p. 4465 - 4472
(2007/10/02)
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- Chemical and Chemotaxonomical Studies of Filices. XLVII. Chemical Studies on the Constituents of Arachniodes nigrospinosa (CHING) CHING, A. festina (HANCE) CHING and A. mutica OHWI
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Two new compounds, II and III, were isolated, together with 4-hydroxynicotinamide, from the fronds of both Arachniodes nigrospinosa and A. festina.The structures of II and III were elucidated as (E)-1-(2,3,4,6-tetramethoxyphenyl)but-2-en-1-one (E)-1-(2,3,4,6-tetramethoxyphenyl)pent-2-en-1-one, respectively.Ryomenin (I) was isolated from the fronds of A. mutica.Keywords - Arachniodes nigrospinosa; Arachniodes festina; Arachniodes mutica; Aspidiaceae; (E)-1-(2,3,4,6-tetramethoxyphenyl)but-2-en-1-one; (E)-1-(2,3,4,6-tetramethoxyphenyl)pent-2-en-1-one; ryomenin; 4-hydroxynicotinamide; phloroglucinol; chemotaxonomy.
- Tanaka, Nobutoshi,Yamazaki, Naomi,Hori, Kazuyuki,Murakami, Takao,Saiki, Yasuhisa,Chen, Chiu-Ming
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p. 1355 - 1358
(2007/10/02)
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