Tocotrienols have been reported to have higher biological activities than tocopherols. We investigated the antitumor effect of tocotrienols both in vivo and in vitro. Oral administration of tocotrienols resulted in significant suppression of liver and lung carcinogenesis in mice. In human hepatocellular carcinoma HepG2 cells, delta-tocotrienol exerted more significant antiproliferative effect than alpha-, beta-, and gamma-tocotrienols. delta-Tocotrienol induced apoptosis, and also tended to induce S phase arrest. On the other hand, gene expression analysis showed that delta-tocotrienol increased CYP1A1 gene, a phase I enzyme. Although further study will be necessary to investigate possible adverse effect, the data obtained in present study suggest that tocotrienols could be promising agents for cancer prevention.
