We have previously reported that substantial amounts of
tocotrienols were present in the skin of animals fed a diet containing a
tocopherols and
tocotrienols rich fraction (T-mix) extracted from
palm oil, and further, that sesame
lignans enhanced
tocotrienol levels in the skin. The present studies were undertaken to determine whether dietary
tocotrienols and those with
sesamin could protect the skin from damage induced by UVB irradiation in hairless mice fed four diets: a
vitamin E-free diet, a 50 mg/kg
alpha-tocopherol diet, a 229 mg/kg T-mix (with 50 mg
alpha-tocopherol) diet and a 229 mg/kg T-mix with 2 g/kg
sesamin diet. In Experiment 1, mice were fed the diets for 6 wk, and half of the mice were exposed to 180 mJ/cm(2 )of UVB light once daily for 7 d. After the intensity of
sunburn was scored,
vitamin E and
thiobarbituric acid reactive substances (
TBARS) concentrations in the skin and liver were determined. In Experiment 2, hairless mice were initiated with a single application of 7, 12-dimethylbenz[a]
anthracene (DMBA), then 1 wk later mice were fed the experimental diets and subjected to 180 mJ/cm(2) UVB irradiation twice weekly for 20 wk.
Tumor incidences were counted once a week.
Tocotrienols were detected in the skin of mice fed T-mix, but their concentrations were significantly lower than for
alpha-tocopherol.
Sesamin elevated
tocotrienol contents in the skin. In spite of the high
alpha-tocopherol contents, the effects of
alpha-tocopherol on
sunburn and incidence of
tumor were slight. T-mix fed groups reduced the extent of
sunburn and incidence of
tumor, and further reduction of
sunburn and incidence of
tumor were observed in the T-mix with
sesamin group. These results suggest that dietary
tocotrienols protect the skin more strongly than
alpha-tocopherol against damage induced by UVB and
sesamin enhances
tocotrienol effects.