The 13C NMR spectrum (Table 1) showed 16 carbon signals,
obviously 13 of which were for the xanthone skeleton,
and also proved the presence of the methylenedioxy group at
δ 100.9 and two methoxyl groups at δ 60.5, 57.7. All protonated
carbons were assigned by analysis of the HSQC and
DEPT spectrum.