Protective effect of food omponent against oxidative stress induced by UV irradiation

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 16500505
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Eating habits, studies on eating habits
• Research Institution: Ochanomizu University
• Principal Investigator: FUJIWARA Yoko Ochanomizu University, Department of Nutrition and Food Science, Associate Professor, 生活科学部, 助教授 (50293105)
• Co-Investigator(Kenkyū-buntansha): SEYAMA Yousuke Ochanomizu University, Department of Nutrition and Food Science, Professor, 生活科学部, 教授 (90010082)
• Project Period (FY): 2004 – 2005
• Keywords: melanogenesis / food component / UV irradaition / oxidative stress / protective effect

Research Abstract

Melanogenesis is the protective reaction of skin to prevent the cellular DNA damage induced by UV irradiation. As excessive accumulation of melanin is undesirable, however, many studies to inhibit melanogenesis were reported in cosmetic research area. We tied to find out the factors in food to inhibit melanogenesis by oral supplementation.
At first, we tried seven kinds of tea extracts from Okinawa to examine the effect of melanin contents in B16 melanoma cells. Most of the tea extracts had no effect except Gettou (Alminia specicosa K.Schum.). The effect of Gettou extract on the activity tyrosinase, a limiting enzyme of melanin synthesis, was investigated. When we tried Gettou in cell-free system using mushroom tyrosinase, Gettou did not inhibit the activity. However, the activity of tyrosinase from B16 melanoma cells incubated with Gettou was lower than cells treated with ascorbic acid. Gettou treatment decreased both mRNA levels and protein levels of tyrosinase in B16 melanoma cells. Gettou had no effect on protein degradation. These results suggested that Gettou treatment decreased the tyrosinase in B16 melanoma cells in transcriptional level.
We tried to examine the effect of Gettou by oral supplementation in vivo. Wister-Maples guinea pigs were given water or Gettou tea for five weeks. Their back hair was removed and treated with UV. Although the L^* values of back skin and DOPA positive melanocytes were examined, oral supplementation of Gettou did not show the significant inhibitory effect.