Submitted to: American Association of Cereal Chemists Meetings
Publication Type: Abstract only
Publication Acceptance Date: 6/23/2013
Publication Date: 10/2/2013
Citation: Chen, M., Choi, S.H., Kozukue, N., Kim, H., Friedman, M., Mcclung, A.M. 2013. Bioactive compounds in pigmented rice bran inhibit growth of human cancer cells. American Association of Cereal Chemists Meetings. Sept. 29- Oct. 2, 2013 Albuquerque, NM. http://www.aaccnet.org/meetings/Documents/2013Abstracts/2013Oab26.htm Interpretive Summary:
Technical Abstract: Rice bran contains both lipophilic and hydrophilic antioxidants. Our previous studies have shown that pigmented rice cultivars contained several-fold higher total phenolic concentrations and antioxidant capacities than non-pigmented cultivars. We investigated three rice brans (purple, red and light-brown) for their bioactivities in growth inhibition of human cancer cells using the microculture tetrazolium (MTT) assay. The compositions of phenolics in the three bran extracts were also determined by HPLC. Based on the calculated IC50 values (concentration of freeze-dried extract that inhibited 50% of the cancer cells under the test conditions), the light-brown bran had no effect on the cells, the purple bran exhibited a minor inhibitory effect on two cell lines, bone marrow erythroid leukemia (HEL) and cervix adenocarcinoma (HeLa), and the red bran exhibited stronger inhibitory effects on HeLa and stomach adenocarcinoma (AGS) cells. High concentrations of protocatechuic acid and anthocyanins in purple bran extract and proanthocyanidins in red bran extract were identified and may have contributed to the bioactivities against the cancer cells. The red-bran extract was further fractionated into three fractions sequentially on a Sephadex column. Fraction-2 and -3 had anticancer effects against AGS, HeLa and HepG2 cancer cells, whereas fraction-3, rich in oligomers and polymers of proanthocyanidins, had the strongest activity. As a follow-up study, we evaluated the concentrations of proanthocyanidin in red bran of a set of rice germplasm. Differences of greater than 4-fold in proanthocyanidin concentration were observed. This suggests that genetic resources exist that can be used to increase proanthocyanidin concentration using traditional breeding that will lead to new cultivars with enhanced health beneficial properties.