Inhibitory effect of sodium 5,6-benzylidene ascorbate (SBA) on the elevation of melanin biosynthesis induced by ultraviolet-A (UV-A) light in cultured B-16 melanoma cells.
Sodium 5,6-benzylidene ascorbate (SBA) is a conjugate of ascorbic acid (Asc) with benzyaldehyde. It has been found that the antioxidant activity of SBA is more stable and has a longer lifetime in living cells and organs than Asc. In this study, we investigated the effect of SBA on the induction of melanin in cultured melanoma (B-16) cells irradiated by UV-A. Melanin content of B-16 cells was significantly increased by UV-A irradiation. The induction was abolished by mannitol and particularly by superoxide dismutase, suggesting the involvement of O2- in the biosynthesis of melanin in cultured melanoma cells. This was theorized by the fact that the induction was also observed in B-16 cells treated with superoxide anion radicals chemically generated in the hypoxanthine/xanthine oxidase-reaction system, instead of UV-A irradiation. The induction of melanin caused by UV-A irradiation was suppressed by SBA in a dose-dependent manner. To elucidate the mechanism of this suppressive effect, the scavenging activity against O2-, and the inhibitory effect of SBA on tyrosinase activity were examined. ESR spectrometric analysis showed that SBA strongly scavenged O2-, and the presence of SBA in the medium remarkably inhibited the tyrosinase activity in cultured B-16 melanoma cells. It can be concluded that SBA effectively inhibits the melanin biosynthesis in B-16 melanoma cells induced by reactive oxygen species (ROS) generated by UV-A irradiation via tyrosinase.
Kojima
S
S
Research Institute for Biosciences, Science University of Tokyo, Chiba, Japan.
Yamaguchi
H
H
Morita
K
K
Ueno
Y
Y
D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D001597:Benzylidene Compounds / Q000494:pharmacology*; D016166:Free Radical Scavengers; D008543:Melanins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D008546:Melanoma, Experimental / Q000378:metabolism* / Q000473:pathology; D017382:Reactive Oxygen Species; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays
D000975:Antioxidants; D001597:Benzylidene Compounds; D016166:Free Radical Scavengers; D008543:Melanins; D017382:Reactive Oxygen Species; D001205:Ascorbic Acid; C070680:zilascorb