Spinach Helps In Fight Against Prostate Cancer

Spinach Helps In Fight Against Prostate Cancer

TSUKUBA, JapanA carotenoidfound in spinach and other green leafy vegetables may help to fight againstprostate cancer, according to a study conducted by scientists from the NationalFood Research Institute in Japan. The study, published in the September issue ofthe Journal of Nutrition (134:2237-2243,2004)(www.nutrition.org), examined the effects of neoxanthin, a carotenoid in greenleafy vegetables that has been reported to exert potent antiproliferativeeffects via apoptosis induction on human prostate cancer cells.

Scientists investigated the gastrointestinal metabolism ofneoxanthin in mice and the in vitro digestion of spinach, and estimated theantiproliferative effect of neoxanthin metabolites on PC-3 human prostate cancercells. Two hours after the oral administration to mice of purified neoxanthin,unchanged neoxanthin and stereoisomers of neochrome were detected in the plasma,liver and small intestinal contents.

To estimate the effect of intragastric acidity on theconversion of dietary neoxanthin into neochrome (epoxide-furanoidrearrangement), spinach was digested in vitro by incubating it with a pepsin-HClsolution at pH 2.0 or 3.0 (gastric phase) followed by a pancreatin-bile saltsolution (intestinal phase). Spinach neoxanthin was largely converted intoneochrome during the digestion when the gastric phase was set at pH 2.0, whereasthe rearrangement was observed to a lesser extent at pH 3.0. neochromedose-dependently inhibited the proliferation of PC-3 cells as well as neoxanthinat concentrations 20 µmol/L.

Although neoxanthin induced evident apoptotic cell death,neochrome inhibited the cell proliferation without obvious apoptosis induction.The results indicate that dietary neoxanthin is partially converted intoneochrome by intragastric acidity before intestinal absorption and thatneochrome exhibits an antiproliferative effect on PC- 3 cells by the inductionof cytostasis, the scientists concluded.