Author(s): Ichihashi M, Funasaka Y, Ohashi A, Chacraborty A, Ahmed NU, , Ichihashi M, Funasaka Y, Ohashi A, Chacraborty A, Ahmed NU,
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Abstract Oral vitamin E (alpha-tocopherol) supplementation has been reported to improve facial hyperpigmentation. The compound of alpha-tocopherol and ferulic acid, also an antioxidant connected with an ester bond, alpha-tocopheryl ferulate (alpha-TF) can absorb ultraviolet (UV) radiation and thus maintain tocopherol in a stable state. Our aim was to determine whether alpha-TF can be applied to improve and prevent facial hyperpigmentation induced by UV as a whitening agent as well as an antioxidant. In this study, the effects of alpha-TF on melanogenesis were examined using cultured human melanoma cells and normal human melanocytes in vitro. alpha-TF solubilized in 0.5\% lecithin inhibited melanization significantly at the concentration of 30 micrograms/ml compared with arbutin (100 micrograms/ml), kojic acid (100 micrograms/ml), ascorbic acid (600 micrograms/ml), and tranexamic acid (600 micrograms/ml). alpha-TF had no effect on the protein amounts of tyrosinase, TRP (tyrosinase related protein)-1, and TRP-2 of human melanoma cells exposed to UV radiation, but inhibited tyrosine hydroxylase activity. alpha-TF neither directly inhibited tyrosinase activity of the large granule fraction extracted from melanoma cells, nor modulated glycosylation of tyrosinase. These results suggest that alpha-TF may be a candidate for whitening agent which suppresses melanogenesis, possibly by inhibiting tyrosine hydroxylase activity in an indirect manner. Further, alpha-TF decreased the amount of 8-hydroxydeoxyguanosine produced indirectly through active oxygen species (AOS) in guinea pig skin exposed to 2 times the minimal erythema dose of UVB radiation, but did not suppress the direct formation of cyclobutane pyrimidine dimers and (6-4) photoproducts. Thus alpha-TF may reduce AOS-induced DNA damage and thereby contribute at least in part to suppressing or retarding skin cancer development.
This article was published in Anticancer Res
and referenced in Dermatology and Dermatologic Diseases