Cancer-preventive activities of tocopherols and tocotrienols.
The cancer-preventive activity of vitamin E has been studied. Whereas some epidemiological studies have suggested a protective effect of vitamin E against cancer formation, many large-scale intervention studies with alpha-tocopherol (usually large doses) have not demonstrated a cancer-preventive effect. Studies on alpha-tocopherol in animal models also have not demonstrated robust cancer prevention effects. One possible explanation for the lack of demonstrable cancer-preventive effects is that high doses of alpha-tocopherol decrease the blood and tissue levels of delta-tocopherols. It has been suggested that gamma-tocopherol, due to its strong anti-inflammatory and other activities, may be the more effective form of vitamin E in cancer prevention. Our recent results have demonstrated that a gamma-tocopherol-rich mixture of tocopherols inhibits colon, prostate, mammary and lung tumorigenesis in animal models, suggesting that this mixture may have a high potential for applications in the prevention of human cancer. In this review, we discuss biochemical properties of tocopherols, results of possible cancer-preventive effects in humans and animal models and possible mechanisms involved in the inhibition of carcinogenesis. Based on this information, we propose that a gamma-tocopherol-rich mixture of tocopherols is a very promising cancer-preventive agent and warrants extensive future research.
Ju
Jihyeung
J
Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
Picinich
Sonia C
SC
Yang
Zhihong
Z
Zhao
Yang
Y
Suh
Nanjoo
N
Kong
Ah-Ng
AN
Yang
Chung S
CS
D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D016022:Case-Control Studies; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000517:prevention & control; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects; D024505:Tocopherols / Q000378:metabolism / Q000494:pharmacology*; D024508:Tocotrienols / Q000494:pharmacology*
D016588:Anticarcinogenic Agents; D000975:Antioxidants; D052246:Cyclooxygenase 2 Inhibitors; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D018160:Receptors, Cytoplasmic and Nuclear; D024508:Tocotrienols; D024505:Tocopherols