Luteolin is a
flavone which occurs in medicinal plants as well as in some vegetables and spices. It is a natural
anti-oxidant with less
pro-oxidant potential than the
flavonol quercetin, the best studied
flavonoid, but apparently with a better safety profile. It displays excellent radical scavenging and cytoprotective properties, especially when tested in complex
biological systems where it can interact with other
anti-oxidants like
vitamins.
Luteolin displays specific anti-inflammatory effects at micromolar concentrations which are only partly explained by its
anti-oxidant capacities. The anti-inflammatory activity includes activation of anti-oxidative
enzymes, suppression of the NFkappaB pathway and inhibition of pro-inflammatory substances. In vivo,
luteolin reduced increased vascular permeability and was effective in animal models of
inflammation after parenteral and oral application. Although
luteolin is only a minor component in our nutrition (less than 1 mg/day) epidemiological studies indicate that it has the potential to protect from diseases associated with inflammatory processes such as
cardiovascular disease.
Luteolin often occurs in the form of
glycosides in plants, but these are cleaved and the aglycones are conjugated and metabolized after nutritional uptake which has to be considered when evaluating in vitro studies. Some data for oral and topical bioavailability exist, but more quantitative research in this field is needed to evaluate the physiological and therapeutical potential of
luteolin.