Results 231 to 240 of about 52,286 (257)
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Xanthones fromChironia krebsii
Phytochemistry, 1991Abstract From a dichloromethane extract of the aerial parts and from a methanolic root extract of Chironia krebsii , 11 1-hydroxyxanthones and six xanthone glycosides have been isolated. The glycosides 5-hydroxy-3-methoxy-1- O -primeverosylxanthone, 1-hydroxy-3-methoxy-5- O -primeverosylxanthone, 5-hydroxy-3-methoxy-1- O -β- d -glucosyl-xanthone, 3,5,
J.-L. Wolfender +3 more
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Acta Crystallographica Section C Crystal Structure Communications, 1990
C 13 H 8 O 2 cristallise dans P2 1 2 1 2 1 avec a=14,072, b=13,627, c=4,878A, Z=4 ; affinement jusqu'a R=0,077. La molecule est plane sauf pour l'atome O du carbonyl (0,13A hors du plan). Les cycles benzene ne sont pas des hexagones reguliers mais la distorsion est symetrique et la molecule a la symetrie C 2v approximative. Il n'y a pas de distances
S. Onuma, K. Iijima, I. Oonishi
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C 13 H 8 O 2 cristallise dans P2 1 2 1 2 1 avec a=14,072, b=13,627, c=4,878A, Z=4 ; affinement jusqu'a R=0,077. La molecule est plane sauf pour l'atome O du carbonyl (0,13A hors du plan). Les cycles benzene ne sont pas des hexagones reguliers mais la distorsion est symetrique et la molecule a la symetrie C 2v approximative. Il n'y a pas de distances
S. Onuma, K. Iijima, I. Oonishi
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Phytochemistry, 1989
Abstract Since the last review in 1980, over eighty new xanthones have been isolated from the Guttiferae. These are listed with reference to structure elucidation and synthesis. The distribution of xanthones is examined in relation to the taxonomic divisions of the Guttiferae.
Graham J. Bennett, Hiok-Huang Lee
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Abstract Since the last review in 1980, over eighty new xanthones have been isolated from the Guttiferae. These are listed with reference to structure elucidation and synthesis. The distribution of xanthones is examined in relation to the taxonomic divisions of the Guttiferae.
Graham J. Bennett, Hiok-Huang Lee
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A xanthone from Shultesia guianensis
Fitoterapia, 2001The isolation of 1-hydroxy-3,7-dimethoxyxanthone (1) from Shultesia guianensis is reported along with relevant NMR spectra, including new data by two-dimensional NMR experiments (HMQC and HMBC).
F J, Monte, F P, Soares, R, Braz-Filho
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Naturally-Occurring Xanthones: Recent Developments
Current Medicinal Chemistry, 2005A literature survey covering the report of naturally occurring xanthones from January 2000 to December 2004, with 219 references, is presented in this review. Among 515 xanthones reported in this period, 278 were new natural xanthones. These xanthones have been identified from 20 families of higher plants (122 species in 44 genera), fungi (19 ...
L M M, Vieira, A, Kijjoa
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New Xanthones from Psorospermum febrifugum
Journal of Natural Products, 1987The isolation and structural determination of two new xanthone derivatives, 1,2,4-trimethoxy-3,8-dihydroxyxanthone, 1,2,4-trimethoxy-3-hydroxyxanthone and a known 2-methoxy-3-hydroxyxanthone from Psorospermum febrifugum var. ferrugineum are reported. The structures were elucidated by extensive analysis of 1H and 13C nmr, ms, and chemical correlations.
A M, Habib +4 more
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Synthesis of Xanthones: An Overview
Current Medicinal Chemistry, 2005Among the known synthetic routes to obtain xanthones, the Grover, Shah, and Shah reaction, the cyclodehydration of 2, 2-dihydroxybenzophenones and electrophilic cycloacylation of 2-aryloxybenzoic acids are the most popular methods. Due to important biological applications of xanthones, some synthetic strategies leading to more complex derivatives ...
M E, Sousa, M M M, Pinto
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Tetraoxygenated Xanthones from Centaurium erythraea
Natural Product Letters, 2000Abstract Three tetraoxygenated xanthones, 1,6-dihydroxy-3,5-dimethoxyxanthone, 3-hydroxy-1,5,6-trimethoxyxanthone and 1,3,5-trihydroxy-2-methoxyxanthone, were isolated for the first time from the aerial parts of C. erythraea. Their structures were established by spectroscopic means and by comparison with literature references.
Valentão, Patrícia +4 more
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Planta Medica, 1994
Five xanthones have been isolated from Garcinia cowa Roxb. (Guttiferae): cowanin (1), cowanol (2), cowaxanthone (3), 1,3,6-trihydroxy-7-methoxy- 2-5-bis(3-methyl-2-butenyl)xanthone (4), and norcowanin (5). The structures were assigned by spectroscopic studies. Xanthones 2 and 3 showed moderate antimicrobial activity against Staphylococcus aureus.
P, na Pattalung +3 more
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Five xanthones have been isolated from Garcinia cowa Roxb. (Guttiferae): cowanin (1), cowanol (2), cowaxanthone (3), 1,3,6-trihydroxy-7-methoxy- 2-5-bis(3-methyl-2-butenyl)xanthone (4), and norcowanin (5). The structures were assigned by spectroscopic studies. Xanthones 2 and 3 showed moderate antimicrobial activity against Staphylococcus aureus.
P, na Pattalung +3 more
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Antioxidant Xanthones from Garcinia vieillardii
Journal of Natural Products, 2004Two new xanthones, 6-O-methyl-2-deprenylrheediaxanthone B (1) and vieillardixanthone (2), were isolated from the stem bark of Garcinia vieillardii, as were four known compounds (4-7). The structures of 1 and 2 were determined by means of spectroscopic analysis and chemical derivatization.
Hay, Anne-Emmanuelle +7 more
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