Colon cancer releases alpha-tocopherol from its O-glycosides better than normal colon tissue.

ABSTRACT

BACKGROUND/AIMS: Free radicals, in a colon, may damage DNA, make difficult DNA repair and change course of post-translational modifications of regulatory proteins, which promote tumor initiation and progression. Therefore risk of colon cancer is closely related to diet and other lifestyle factors. Dietary antioxidants, such as vitamin E, should reduce the levels of harmful oxidation products. However vitamin E is not soluble in water, which decreases its bioavailability. As O-glycosides of alpha-tocopherol are better soluble in water and penetrate to tissues easier than free alpha-tocopherol, the aim of our work was to investigate the rate of release the free tocopherol from its O-glycosides in colon cancer, in comparison to human healthy colon tissue. METHODOLOGY: The activities of enzymes catalysing hydrolysis of alpha-tocopheryl glucoside (1a) and mannoside (1b) as well as p-nitrophenyl beta-glucoside (2a) and mannoside (2b) in cancer and healthy human colon tissues, were determined according to the modified method described by Zwierz et al. RESULTS: The alpha-tocopherol and p-nitrophenol were significantly better released from the respective glucosides and mannosides in cancer tissue than in "healthy" human colon tissues, with p = 0.000947 for la, p = 0.033024 for 1b; p = 0.0028 for 2a, and p = 0.0033 for 2b, respectively. CONCLUSION: Alpha-tocopherol and p-nitrophenol are released from the O-glycosides of glucose and mannose in significantly higher amount in colon cancer than in healthy tissues. The alpha-tocopherol O-glycosides can be considered as prodrugs in prevention and treatment of the colon cancer.