Dihydroflavonols from Lannea coromandelica.
The dihydroflavonols, (2R,3S)-(+)-3',5-dihydroxy-4',7-dimethoxydihydroflavonol and (2R,3R)-(+)-4',5,7-trimethoxydihydroflavonol were isolated from the stem bark of Lannea coromandelica, along with the known (2R,3R)-(+)-4',7-di-O-methyldihydroquercetin, (2R,3R)-(+)-4',7-di-O-methyldihydrokaempferol and (2R,3R)-(+)-4'-O-methyldihydroquercetin. All five compounds were isolated for the first time from the genus Lannea; furthermore, (2R,3S)-(+)-3',5-dihydroxy-4',7-dimethoxydihydroflavonol, was a rare cis-type isomer. The structures of all compounds were elucidated by spectroscopic methods including 2D NMR and CD analysis.
Islam
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Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan.
Tahara
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D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification*; D015394:Molecular Structure; D019685:Rosales / Q000737:chemistry*; D013057:Spectrum Analysis
D005419:Flavonoids