Studies on the growth inhibiting and non-cytotoxic effects of tocotrienols on selected cancer cell lines.

Abstract

Tocotrienols found in certain plant oils, like palm, rice bran, grapeseed and annatto seeds, have been reported to possess beneficial properties for humans, including cancer prevention. Since studies on their beneficial effects on human breast cancer cells have been extensively reviewed, the current understanding of how tocotrienols affect other cancer cells deserves further research. Therefore, the aim of this study was to investigate the antiproliferative and non-cytotoxic effects of tocotrienols on human hepatoma HepG2 and colon colorectal Caco-2 cell cultures. The cells were exposed to alpha-, beta-, gamma- or delta-tocotrienols at various concentrations and the antiproliferative activities were measured using MTS-based CellTiter 96 followed by a methylene blue assay for counting cells to evaluate the potential toxicity. The research on HepG2 showed statistically similar cytotoxic effects for both beta- and delta-T3 with no effects for alpha- and gamma-T3. Promising results were found for alpha-, beta- and gamma-T3 against CaCo-2. The exact reasons for the sensitivity of liver cancer cells to tocotrienols are unknown. Inhibition is time and dose-dependent, therefore tocotrienols' homologs show very high toxic or no effects. Tocotrienols appeared to be effective against colon cancer cells. Still, future investigation is necessary to explain the different mechanism of actions to support the antiproliferative effects of these homologs against colon cancer cells.