the other peri-position relative to the
xanthone carbonyl group. The methoxy group resonating at d 3.86
was located at C-7 on the basis of the HMBC correlation of H3-11
with C-7. The remaining singlet aromatic proton at d 6.83 was then
assigned to H-5 according to its HMBC cross peaks with C-6 (d
155.7), C-8a, C-9 (d 181.6), and C-10a (d 157.9). The substituents
at C-3 and C-6 were identified as hydroxy groups according to
the chemical shifts of C-3 and C-6. Consequently, xanthochymone
A was identified as 1,3,6-trihydroxy-7-methoxy-8-(3-hydroxy-3-
methylbutyl)xanthone (1).