Flavonoids are a large class of plant secondary metabolites,
belonging to polyphenol family, which possess pharmacological and nutritional
properties. Their synthesis takes place only in plants, while mammals can
acquire them only with diet. It has been demonstrated that flavonoid uptake
occurs in rat also by the activity of bilitranslocase, a carrier that is involved
in anion transport in liver cell, vascular endothelium and gastric mucosa. A
sequence of bilitranslocase interacting with flavonoid moieties is already known
and characterized. Antibody raised against such protein epitope were shown
to exhibit cross-reactivity against plant membrane proteins in tissues involved
in flavonoid transport and accumulation, such as teguments of carnation
petals and skin of grape berries. Further immunolocalization studies allowed
to demonstrate the presence of cross-reacting protein not only at the level of
tegumental tissues, but also associated to sieve elements and seed teguments
in grape berries.
