Shikonin是紫草的主要成分之一，紫草在傳統中醫上常用於治療皮膚發炎及過敏。本研究的目的在探討shikonin如何影響人類黑色素細胞癌細胞株(A375.S2)。 本研究利用高效液相層析儀(HPLC) 分析人類皮膚癌細胞株(A375.S2) N基乙醯化2- aminofluorene 的量，結果顯示shikonin可以減少N基乙醯化的代謝產物(2-AAF) 的產生，而此影響有計量依成性和培養時間依成性。並發現shikonin可降低人類黑色素細胞癌細胞株(A375.S2) 細胞中NAT的活性， 以及抑制NATl基因(NAT mRNA)。 利用流式細胞計數方法和DNA電泳法，觀察細胞生長、細胞形態、細胞週期以及DNA斷裂的影響。Shikonin可造成人類黑色素細胞癌細胞株(A375.S2) 之細胞週期中止，並引起細胞凋亡，此影響有計量依成性。暴露在shikonin之A375.S2細胞株加強了cyclins與cyclin-dependent kinases活性的表現，並在細胞凋亡及中止細胞週期上扮演重要角色。 本實驗為shikonin對人類黑色素細胞癌細胞株(A375.S2) 之首例研究。; Shikonin is one of the components of Lithospermum erythrorhizon (Chinese herb medicine) used for skin infection and allergy for many generations in the Chinese population. In this study, shikonin was used to determine the inhibition of N-acetylation of 2-aminofluorence (2-AF) in human malignant melanoma cell line (A357.S2). The amounts of N-acetylation and non-N-acetylation of 2-AF were measured by high performance liquid chromatography. The results demonstrated that N-acetylation of AF from examined systems were decreased by shikonin in a dose-dependent manner. We also found out that this effect of shikonin on N-aectylation of AF also was time-course dependent. Apparently shikonin affect N-acetylation of AF in human malignant melanoma cell line (A357.S2). We investigated how shikonin affects human malignant melanoma cells (A375.S2) for determining the inhibition of cell growth, morphological changes, DNA fragmentation, and cell cycle by using flow cytometric assay and DNA gel electrophoresis. After exposure of the cells to shikonin which resulted in cell cycle arrest and cell death through apoptosis. This effect is also dose-dependent manner. Exposure of A375.S2 cells to shikonin induced expression of the cyclins and cyclin-dependent kinases (CDK) activity. These studies demonstrated that cyclins and CDKs play a key role in the inhibition of shikonin-induced apoptosis and cell cycle arrest in A375.S2 cells. This is the first findings to show shikonin affect human malignant melanoma cell lines (A375.S2).
