Digestion, absorption, and cancer preventative activity of dietary chlorophyll derivatives

The growing body of epidemiological and experimental evidence associating diets rich in fruits and vegetables with prevention of chronic diseases such as cancer has stimulated interest in plant food phytochemicals as physiologically active dietary components. Chlorophyll and its various derivatives are believed to be among the family of phytochemical compounds that are potentially responsible for such associations. Dietary chlorophyll is predominantly composed of lipophilic derivatives including chlorophyll a and b (fresh fruits and vegetables), metal-free pheophytins and pyropheophytins (thermally processed fruits and vegetables), as well as Zn-pheophytins and Zn-pyropheophytins (thermally processed green vegetables). Water-soluble derivatives including chlorophyllides, pheophorbides, as well as a commercial-grade derivative known as sodium copper chlorophyllin (SCC) also contribute to the diversity of dietary chlorophyll derivatives. Although the use of chlorophyll derivatives, especially SCC, in traditional medical applications is well documented, it is perhaps the potential of chlorophyll as a cancer preventative agent that has drawn significant attention recently. Biological activities attributed to chlorophyll derivatives consistent with cancer prevention include antioxidant and antimutagenic activity, mutagen trapping, modulation of xenobiotic metabolism, and induction of apoptosis. Although most research has focused on commercial-grade SCC, the extent to which natural chlorophyll derivatives modulate biomarkers of cancer risk is also being explored. Recent research efforts have also included investigation of the impact of digestive factors on chlorophyll structure and bioaccessibility as a means to better understand the extent to which these pigments may be bioavailable in humans and therefore have more systemic impact in the prevention of cancer. (c) 2007 Elsevier Inc. All rights reserved.