探討甲型硫辛酸對B16-F1黑色素瘤細胞中pheomelanin生合成之影響

黑色素以pheomelanin與eumelanin混合型式存於自然界中，其二者在細胞含量受麩胱甘肽調控，且pheomelanin對eumelanin的比例是評估皮膚癌重要因子。硫醇抗氧化劑甲型硫辛酸在過去已被證實，會增加細胞內麩胱甘肽含量，因此本實驗主要探討（1）不同濃度甲型硫辛酸在24、48、72小時三個時間點，對B16-F1黑色素瘤細胞生長情形及細胞內外黑色素含量之影響。（2）不同濃度甲型硫辛酸在72小時，對B16-F1黑色素瘤細胞內外pheomelanin、eumelanin含量及pheomelanin/eumelanin比例之影響。（3）另加入相等濃度非硫醇抗氧化劑維生素C磷酸鎂鹽、維生素E琥珀酸鹽，與硫醇抗氧化劑甲型硫辛酸做比對，觀察在72小時對B16-F1黑色素瘤細胞內外黑色素、pheomelanin、eumelanin含量及pheomelanin/ eumelanin比例之影響。結果顯示：（1）隨甲型硫辛酸濃度時間處理加長，增加B16-F1黑色素瘤細胞數，及降低細胞內外黑色素含量。（2）B16-F1黑色素瘤在甲型硫辛酸處理72小時，增加胞內pheomelanin含量，降低細胞外pheomelanin及細胞內外eumelanin含量，並增加細胞內外pheomelanin/eumelanin比例。（3）維生素C磷酸鎂鹽、維生素E琥珀酸鹽在72小時，增加細胞內黑色素、eumelanin含量，且維生素E琥珀酸鹽可提高細胞內pheomelanin含量，進一步檢測細胞內pheomelanin/eumelanin比例，在維生素E琥珀酸鹽作用下會增加2.9倍。由上述結果得知，維生素C磷酸鎂鹽與控制組在pheomelanin/eumelanin比例無顯著差異，但在甲型硫辛酸抑制細胞內外黑色素含量同時，也增加細胞內外pheomelanin/ eumelanin比例，此比例增加在維生素E琥珀酸鹽處理下也觀察到，對於使用甲型硫辛酸、維生素E琥珀酸鹽使用者而言，可能會增加罹患皮膚癌的危險性。

Melanin is a complex composed of pheomelanin and eumelanin in nature, and its ratio of content is mainly regulated by glutathione. Pheomelanin and eumelanin ratio is an important risk factor of skin cancer. It has been confirmed that thiol antioxidant such as a - lipoic acid could increase glutathione content in cells, and therefore our study was to evaluate [1] the growth and intra/extracellular total melanin content of B16-F1 melanoma cells when treated with different concentrations of a - lipoic acid at 24, 48, and 72 hours intervals, [2 ] the intra/extracellular pheomelanin, eumelanin level, and pheomelanin / eumelanin ratio of B16-F1 melanoma cells 72 hours after being treated with a - lipoic acid, and [3] the intra/extracellular total melanin, pheomelanin, eumelanin, and pheomelanin / eumelanin ratio of B16-F1 melanoma cells 72 hours following the treatment of same concentration of a - lipoic acid, vitamin C phosphate magnesium, and vitamin E succinate. Our results revealed that [1] a - lipoic acid increased the growth of B16-F1 melanoma cells, and decreased intra/extracellular total melanin content, [2] a - lipoic acid increased intracellular pheomelanin content, intra/extracellular pheomelanin/eumelanin ratio, and decreased intra/extracellular eumelanin, intracellular pheomelanin content, and [3] vitamin C phosphate magnesium or vitamin E succinate both increased intracellular total melanin and eumelanin content, and vitamin E succinate considerably increased pheomelanin / eumelanin ratio up to 2.9 fold. Based on these results, we suggest that while use a - lipoic acid and/or vitamin E succinate as inhibitor(s) of total melanin, attention should be simultaneously addressed on the increasing risk of skin cancer.