ARS | Publication request: Growth-inhibitory effects of pigmented rice bran extracts and three red bran fractions against human cancer cells: Relationships to composition and antioxidative activities

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 17, 2012
Publication Date: August 17, 2012
Citation: Chen, M., Choi, S., Kozukue, N., Kim, H., Friedman, M. 2012. Growth-inhibitory effects of pigmented rice bran extracts and three red bran fractions against human cancer cells: Relationships to composition and antioxidative activities. Journal of Agricultural and Food Chemistry. DOI:10.1021/jf3025453.

Interpretive Summary: About 600 million tons of rice grains are harvested worldwide annually. Rice bran, a by-product of the rice milling industry, contributes about 10 percent to the weight of the grain. Brans from pigmented rice varieties contain high amounts of structurally different bioactive compounds and have the potential to serve as so-called functional foods that can promote human health. Rice bran rich in phytonutrients has the potential to help control blood sugar levels, cholesterol metabolism, prostate health, and prevent the growth of cancer cells. The objective of this study was to compare the cancer cell-inhibiting effects of water-soluble bran extracts from light-brown, purple, and red rice varieties against human cancer and normal cell lines in relation to the concentration of phenolic compounds and antioxidative effects. The results show that light-brown bran had no effect on all the cancer cell lines, purple bran exhibited a minor effect on leukemia and cervical cancer cells, and red bran exhibited strong inhibitory effects on cervical and stomach cancer cells. Chemical analyses suggested that proanthocyanidins might be the major compounds in red bran extract attributed to the anti-cancer bioactivity. Red bran has the potential to serve as a functional food supplement for human consumption.

Technical Abstract: We determined the phenolic, anthocyanin, and proanthocyanidin content of three brown, purple, and red rice brans isolated from different rice varieties using HPLC-PDA with the aid of 27 standards of known structure and by matching unknown peaks to a spectral library of known compounds. DPPH and ORAC; and cell-inhibiting effects determined antioxidative capacities by the MTT assays. Based on the calculated IC50 values, light-brown bran had no effect, purple bran exhibited a minor effect on leukemia (HEL) and cervix (HeLa) cells, and red bran exhibited strong inhibitory effects on HeLa and stomach cancer (AGS) cells. High concentrations of protocatechuic acid and anthocyanins in purple bran and proanthocyanidins in red bran were identified. The red-bran was further fractionated on a Sephadex column. Fraction-3 rich in oligomers and proanthocyanidin polymers had the greatest activity. Red bran has the potential to serve as a functional food supplement for human consumption.