Pomegranates have been shown to contain 124 different phytochemicals, and some of them act in concert to exert antioxidant and anti-inflammatory effects on cancer cells. Ellagitannins are bioactive polyphenols present in pomegranate. Pomegranate juice obtained by squeezing the whole fruit has the highest concentration of ellagitannins than any commonly consumed juice and contains the unique ellagitannin, punicalagin. Punicalagin is the known largest molecular weight polyphenol. Pomegranate ellagitannins are not absorbed intact into the blood stream but are hydrolyzed to ellagic acid over several hours in the intestine. Ellagitannins are also metabolized into urolithins by gut flora, which are conjugated in the liver and excreted in the urine. These urolithins are also bioactive and inhibit prostate cancer cell growth. Research on basic mechanisms of action in cell culture, animal model systems, and limited clinical research in prostate cancer patients has been carried out with pomegranate juice. This chapter discusses the evidence for the bioactivity of pomegranate ellagitannins, along with the progress in defining the pharmacokinetics and metabolism of ellagitannins in pomegranate juice in humans.
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