The connectivity of δ 6.87 (H-10) to C-3 (δ 160.7) and δ 5.56 (H-11) to C-4 (δ 101.6) as observed
in the HMBC experiment led to the attachment of pyrano ring A to position C-3 and C-4 in the
xanthone skeleton. Similarly, the other prenylated pyrano ring (ring B) is attached to position C-6 and
C-7 following the observation of 3J and 2J long-range connectivity between H-15 (δ 6.46) and C-6 (δ
145.3), C-7 (δ 117.8) and C-8 (δ 113.7).