Delivery and application of dietary polyphenols to target organs, tissues and intracellular organelles.

At present, dietary polyphenols are popular with consumers because regular consumption of polyphenol-rich foods is likely to be beneficial for human health. However, administrated polyphenols are extensively metabolized in the digestive tract or some other parts before reaching the target organs. Additionally, some of the polyphenols are photosensitive, easily oxidized and are in unfavorable forms. Therefore, a lot of work has been performed to ensure delivery of intact polyphenols to the target organs. We here summarize recent progress in polyphenol-delivery to individual organs, tissues, and cells, in regard to relatively new delivery systems. Polyphenol-delivery systems can be divided into three categories: (i) before delivery into the blood stream (skin, mouth, gastrointestine), (ii) in the blood stream (plasma), and (iii) after the blood stream (brain, spleen, bone marrow, kidney). Polyphenols before the delivery into blood stream must overcome several obstacles to avoid converting into inactive forms by commensal microorganisms, environmental pH, and some others. In the blood, plasma-polyphenol interactions and modifications are very effective for the bioavailability of polyphenols with numerous enzymes. Native forms of polyphenols, successfully out of the blood stream, further go through obstacles such as the blood brain barrier to reach target organs. Recent progress in delivering polyphenols is here discussed on 3 main delivery systems, nanoparticle, liposome, and microemulsion. Moreover, we also focused on delivery systems to intracellular organelles (cell surface, lysosome, mitochondria, nucleus), which are the final targets of polyphenols to perform their beneficial reactions.