Design and development of nanovehicle-based delivery systems for preventive or therapeutic supplementation with flavonoids.

To date more than 4000 compounds are recognized to belong to the class of flavonoids. These natural phenolic drugs are poorly soluble in water and are rapidly degraded and metabolized in the human body, but nevertheless are very promising for their potential contribution to the prevention and therapy of major chronic diseases, including cardiovascular and neurodegenerative diseases and cancer. In recent years a number of flavanols (e.g. catechins), flavonols (e.g. quercetin, myricetin) and isoflavones (e.g. genistein, daidzein) have been confirmed to possess strong antioxidant, anti-inflammatory, anti-proliferative and anti-aging activities. Incorporation into lipidic or polymer-based nanoparticles appears to markedly help the oral delivery of flavonoids, as these particles can protect the drug from degradation in the gastrointestinal tract and, by virtue of their unique absorption mechanism through the lymphatic system, also from first-pass metabolism in the liver. In addition, both oral and parenteral administration of flavonoids exploits a pharmacologic delivery route that guarantees sustained release of the active principle at the desired site of action. A comprehensive review of studies currently available on the in vitro and in vivo experimental administration of flavonoids by means of nanovectors may be of use as a foundation for the development of advanced delivery systems for these powerful compounds, in view of their adoption in primary and secondary disease prevention.