Bougainvinones A–H, Peltogynoids from the Stem Bark of Purple Bougainvillea spectabilis and Their Cytotoxic Activity

Eight new peltogynoids, named bougainvinones
A–H (1–8), were obtained from
the stem bark
of Bougainvillea spectabilis. Their
structures were elucidated by means of physical data (1D and 2D NMR,
HRESIMS) and single-crystal X-ray crystallographic analyses. The peltogynoids,
a rare type of modified flavonoids, are reported for the first time
from this species of the genus Bougainvillea. All
isolated compounds were evaluated for their cytotoxic effects against
five cancer cell lines including KB, Hela S-3, HT-29, MCF-7, and HepG2.
Among them, compound 7 showed cytotoxicity against five
cancer cell lines with IC50 values in the 7.4–9.7
μM range, and compounds 2 and 3 exhibited
cytotoxicity against the KB cell line with IC50 values
of 6.6 and 9.0 μM.