Dietary flavonoids and other polyphenols show great potential
as cancer chemopreventive agents in cell culture studies.1,2
However, because of their low bioavailability as a result of
conjugative metabolism, this does not translate well into in vivo
activity.3 However, polymethoxylated flavonoids (PMFs), the
flavonoid subclass in which all or almost hydroxyls are capped
by methylation, have high oral bioavailability, displaying
antiallergic, antioxidant, antibacterial, antiproliferative, antiinflammatory,
and anticancer activities,4−10 which have aroused
the interest of the food, nutraceutical, and pharmaceutical
industries for the use of these compounds as specialty
ingredients. Meanwhile, hydroxylated polymethoxyflavonoids
(OH-PMFs), which are less abundant PMFs in comparison
with permethoxylated PMFs,11 have drawn more and more
attention recently, because accumulating evidence has
suggested that OH-PMFs have much stronger healthpromoting
biological activities compared with their permethoxylated
counterparts. For example, 5-hydroxy polymethoxyflavones
exhibited greater potencies in anticarcinogenic and
anti-inflammatory effects.12−14