The Structure of Garcinone E

As part of a survey of anti-tumorpromotive chemicals, garcinone E (1) and nine known xanthones, 8-deoxygartanin, gartanin, xanthone I, β-mangostin, garcinone B, 6-deoxy-γ-mangostin, 1, 5, 8-trihydroxy-3-methoxy-2-(3-methyl-2-butenyl)xanthone, γ-mangostin and α-mangostin, together with egonol, were isolated from the fruit hulls of Garcinia mangostana L. collected in Thailand. The structure of garcinone E was elucidated as 1, 3, 6, 7-tetrahydroxy-2, 5, 8-tri-(3-methyl-2-buteny)xanthone by spectroscopic methods, including the application of a number of two dimensional (2D)NMR techniques (1H-1H, 13C-1H correlation spectroscopy (COSY), nuclear Overhauser effect spectroscopy (NOESY) and correlation via long-range coupling (COLOC).