Inhibitory Effects of (2′R)‐2′,3′‐dihydro‐2′‐(1‐hydroxy‐1‐methylethyl)‐2,6′‐bibenzofuran‐6,4′‐diol on Mushroom Tyrosinase and Melanogenesis in B16‐F10 Melanoma Cells

(2′R)‐2′,3′‐Dihydro‐2′‐(1‐hydroxy‐1‐methylethyl)‐2,6′‐bibenzofuran‐6,4′‐diol (DHMB) is a natural compound extracted from Morus notabilis. It was found that DHMB acts as a competitive inhibitor against mushroom tyrosinase with a Ki value of 14.77 μM. Docking results further indicated that it could form strong interactions with one copper ion with a distance of 2.7 Å, suggesting the mechanism of inhibition might be due to chelating copper ions in the active site. Furthermore, melanin production in B16‐F10 murine melanoma cells was significantly inhibited by DHMB in a concentration‐dependent manner without cytotoxicity. The results of western blotting also showed that DHMB decreased 3‐isobuty‐1‐methxlzanthine‐induced mature tyrosinase expression. Taken together, these findings indicated that DHMB may be a new promising pigmentation‐altering agent for agriculture, cosmetic, and therapeutic applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Regulation of pigmentation by substrate elasticity in normal human melanocytes and melanotic MNT1 human melanoma cells

The elasticity of the cellular microenvironment is a key regulator of cellular physiology in many cell types. To investigate the effects of substrate stiffness on the pigmentation process, we cultured normal human melanocytes (NHM) and MNT1 melanoma cells on laminin‐coated polydimethylsiloxane (PDMS) substrates of different stiffness. The dendricity of NHM and MNT1 cells was reduced as the substrate stiffness decreased, and the degree of melanosome transfer from NHM or MNT1 cells to normal human keratinocytes was decreased on softer substrates with the reduced dendricity. Gene and protein expressions of MITF, tyrosinase, TRP2, and gp100/PMEL17 exhibited a consistent decreasing trend with the decreasing stiffness. Because the stiffness sensing is mediated by focal adhesion complex through integrin receptors, we checked laminin specific integrin alpha 6 and p‐FAK for MNT1 cells to observe that the substrate adhesion was weakened as the substrate stiffness decreased. Weaker adhesion on a softer substrate was accompanied by dynamic shape changes in MNT1 cells with higher speed and larger scattering. Dendritic MNT1 cells cultured on a stiffer substrate exhibited lower migration with smaller root mean squared displacement. These results demonstrate the possibility that skin pigmentation can be influenced by mechanical properties of the cellular microenvironment and can increase when the skin becomes stiff.     

驱白艾力勒思亚散乙醇提取物对小鼠B16黑素瘤细胞增殖及黑素生成的影响

目的研究维药复方驱白艾力勒思亚散(QBALLSYS)乙醇提取物对小鼠B16黑素瘤细胞增殖、黑素合成以及酪氨酸酶活性的影响。方法以MTT法测定培养的B16黑素瘤细胞的增殖活性;氢氧化钠法测定黑素生成量;体外氧化多巴反应方法测定酪氨酸酶活性。结果与空白对照组相比,驱白艾力勒思亚散乙醇提取物对B16黑素瘤细胞的增殖活性、黑素生成量、酪氨酸酶活性均有显著性作用(P<0.05或P<0.01)。驱白艾力勒思亚散乙醇提取物对小鼠B16黑素瘤细胞的增殖活性有上调作用,对细胞黑素生成以及酪氨酸酶的活性均有不同程度的促进作用。结论驱白艾力勒思亚散的乙醇提取物具有促进黑素细胞增殖和合成黑素的作用。     

三叶青提取物对A375细胞增殖、酪氨酸酶活性及黑色素合成的影响

目的探讨三叶青乙醇提取物对人恶性黑色素瘤A375细胞增殖、酪氨酸酶活性及黑色素合成的影响。方法 采用MTT比色法,测定不同浓度三叶青乙醇提取物对A375细胞体外抑制作用;比色法测定酪氨酸酶活性和黑色素含量。结果在质量浓度为1～625μg/ml范围内,随着三叶青乙醇提取物浓度增大可抑制A375细胞的增殖(P<0.01);三叶青乙醇提取物浓度在1～5μg/ml时,对酪氨酸酶活性和黑色素合成抑制有增加趋势;而在25～625μg/ml时,对A375细胞有一定毒性。结论三叶青乙醇提取物在一定浓度范围内(1～625μg/ml)能抑制A375细胞的增殖,且呈剂量依赖关系。     

多巴染色与光密度法在细胞水平评价原料美白功效的应用研究

目的：在细胞水平评价化妆品原料的美白功效。方法：体外培养小鼠黑素瘤细胞B16,通过多巴特异性染色,利用平均光密度法检测化妆品原料对细胞中黑素生成的抑制作用。结果：多巴对细胞内黑素具有特异性染色,浓度为25μg/ml的曲酸对黑素细胞内黑素生成的抑制率为（48.44±3.44）%,板内标准偏差值仅为7.09%,板间标准偏差值小于7.22%,曲酸、白藜芦醇和绿茶提取物均对细胞内黑素的生成具有较为明显的抑制作用,而桑白皮提取物对细胞内黑素生成几乎没有抑制作用。结论：采用多巴染色和平均光密度的方法检测黑素瘤细胞中黑素含量,精度较高、板间板内误差较小,能够成功用于化妆品原料美白功效的评测。