Quercetin actually has a rival for
most powerful flavonoid, and that is Curcumin, the active ingredient in Tumeric, which is a main ingredient in curry powder.
Studies in rabbits are somewhat limited (we tend to do
most of our scientific research on mice), but the
flavonoids found in orange peels may have
powerful protective effects — some studies suggest that
flavonoids can inhibit certain proteins that have been linked to obesity and cancer.