Whole Wheat Phytochemicals And Potential Health Benefit
A whole grain consists of the intact, ground, cracked or flaked caryopsis, whose principal anatomical components - the starchy endosperm, germ and bran - are present in the same relative proportions as they exist in the intact caryopsis. Increased consumption of whole grains has been associated with reduced risk of major chronic diseases. Phytochemicals are bioactive non-nutrient plant compounds in fruits, vegetables, whole grains, and other plant foods. Whole grain foods offer a wide range of phytochemicals that are proposed to be responsible for the health benefits of whole grain consumption. The objective of this dissertation was to determine the phytochemical content, antioxidant activity, and antiproliferative activity of whole wheat and its milled fractions, the bran/shorts, germ, and endosperm. The most studied whole grain phytochemicals are phenolics, compounds with one or more aromatic rings and one or more hydroxyl groups. Phenolics are generally found bound to cell wall polymers and are therefore insoluble upon extraction. The bound fraction contributed 53.8 to 69.7% of the total phenolic content of the six diverse wheat varieties analyzed. The insoluble-bound fraction of the bran/shorts had the highest phenolic content followed by the whole seed, germ, and endosperm. Lutein was the predominant carotenoid found in whole wheat and its milled fractions. Zeaxanthin, Beta-carotene, and Beta-cryptoxanthin were also detected. Mainly Alpha- and Beta-tocopherols and tocotrienols were found in all varieties of whole wheat. The bran/shorts fraction consisted mainly of tocotrienols, though the germ fraction consisted mainly of tocopherols. The bran/shorts had the highest insoluble-bound ORAC followed by the whole seed, germ, and endosperm. Free phenolics extracts from the germ and insoluble-bound phenolics extracts from whole wheat and its milled fractions significantly inhibited the proliferation of HepG2 cells after 96 hours at 10 mg/mL. The data provided in this dissertation, supports the idea that the potential health benefit in the lower gastrointestinal tract from whole wheat consumption is due to the antioxidant activity of phenolics compounds from the insoluble-bound fraction of whole wheat. This dissertation also lays the foundation for future research regarding the potential health benefit of whole wheat phytochemicals.
dissertation or thesis