Phytochemical investigation of xanthones of Eustoma grandiflorum (Raf.) Shinners.

Six polyoxygenated xanthones were isolated from the roots of Eustoma grandiflorum (Raf.) Shinners collected in Texas. Structural elucidation of five of these xanthones (1-hydroxy-3,7-dimethoxyxanthone, 1-hydroxy-3,5-dimethoxyxanthone, 1-hydroxy-3,5,6,7-tetramethoxyxanthone, 1-hydroxy-3,5,6,7,8-pentamethoxyxanthone, and 1-hydroxy-3,7,8-trimethoxyxanthone) was accomplished via UV, IR, NMR, and mass spectrometry; traditional physical-chemical methods; or direct comparison with a prepared derivative. The sixth xanthone derivative was characterized incompletely. The pentamethoxyxanthone is a new compound and has been designated generically as eustomin. The probable occurrence of these six xanthone compounds in the plant as glycosides is reported.