长波紫外线照射对小鼠黑素瘤细胞的影响

[目的]研究不同剂量UVA照射对体外培养B_16小鼠黑素瘤细胞的形态、增殖率、黑素含量和酪氨酸酶活性的影响。[方法]选用B_16小鼠黑素瘤细胞 ,经不同剂量的UVA照射后 ,采用MTT法测定细胞的增殖 ,参照HideyaAndo等的方法测定酪氨酸酶活性和黑素含量。[结果]UVA照射后 ,黑素含量增加 (P<0.01) ,酪氨酸酶活性提高 (P<0.05) ,细胞增殖率上升 ,照射剂量在0.6、1.2、1.8J/cm2时 ,细胞增殖率的变化有显著性 (t=2.495、2.645、3.081,均为P<0.05)。[结论]随着照射剂量的增加 ,黑素含量增加 ,酪氨酸酶活性提高 ,细胞的增殖率增加 ,但UVA的促黑素瘤细胞增殖作用是有限的     

The superoxide anion may mediate short- but not long-term effects of ultraviolet radiation on melanogenesis

Abstract The present study was carried out to examine the role of reactive oxygen species in mediating the melanogenic effects of UVR. B16 mouse melanoma cells responded to a single dose of UVR by showing increases in their melanin content. Although there was a small increase in melanin at 48-72 hours, which was associated with a rise in tyrosinase activity at 48 h, the greatest change occurred at 3 h and this was not associated with an increase in tyrosinase activity. This short-term response, unlike the more delayed melanogenic response, was reduced by superoxide dismut-ase (SOD). Xanthine oxidase (XO), which generates the superoxide anion (O₂). also increased the melanin content of B16 melanoma cells with effects at 3 h and 48 h. As with UVR, the delayed response was accompanied by an increase in tyrosinase activity but no such association was evident at 3 h. In addition, the short-term effect, like that seen with UVR, was reduced with SOD and to a lesser extent with catalase. In contrast to the effects found with XO, glucose oxidase, which generates hydrogen peroxide, had no effect on the melanin content or tyrosinase activity of the B16 cells. These results confirm previous observations that UVR is able to act directly on cells to bring about delayed increases in melanogenesis. They further demonstrate that UVR also stimulates melanogenesis through a more rapid action that is not associated with an activation of tyrosinase. This effect could be mediated by the O₂ which, rather than activating tyrosinase, could act by serving as a substrate for the enzyme.     

抑制剂对酪氨酸酶影响的初步研究

采用酶动力学及聚丙烯酰胺凝胶电泳方法研究了ＮａＨＳＯ３、ＮａＮ３、ＫＳＣＮ、ＤＤＣ对酪氨酸酶的抑制作用。ＮａＨＳＯ３、ＮａＮ３、ＫＳＣＮ为非竞争性抑制作用，随着抑制剂浓度增加，酶活性逐渐减弱。当ＮａＨＳＯ３、ＮａＮ３、ＫＳＣＮ的浓度分别达到１．２ｍｍｏｌ／Ｌ１２。５ｍｍｏｌ／Ｌ１２．５ｍｍｏｌ／Ｌ时，酶活性的抑制率为１００％、５０％、２４％。ＤＤＣ对酪氨酸酶的抑制作用为竞争性抑制作用，其浓度达４ｍｍｏｌ／Ｌ时，酶活性１００％受到抑制。     

太子参化学成分、药理作用和应用的研究进展

太子参Pseudostellariae Radix是中国传统补益中药材之一,兼具药用和食疗功效,主要含有挥发油、多糖、环肽、生物碱、皂苷、酚类等成分,具有降血糖、抗炎、抗癌、保护细胞、抑制酪氨酸酶、免疫调节等药理作用。对太子参的化学成分及其药理作用,以及太子参在临床、食疗、保健食品、化妆品、兽药制剂和功能性饲料添加剂等方面应用进行总结,为太子参进一步开发利用提供依据。     

Molecular approach to the nucleo-melanosomal interaction in human melanoma cells

This paper presents evidence that L-tyrosine oxidation products and 5,6-dihydroxyindole, an intermediate of melanin synthesis bind to and modify DNA structure, as tested by extracting cell DNA, using topoisomerase I and denaturation assays. When supercoiled plasmid pCU18 or pBR322 DNAs are treated with 5,6-dihydroxyindole the supercoiled species disappear and are converted to species less mobile in a gel retardation test with respect to relaxed DNA. 5,6-Dihydroxyindole causes an easier acid denaturation of the double helix. The results, that are dose dependent,would point to both intercalation and cross-linking of DNA by 5,6-dihydroxyindole and its oxidation product(s). ³H-L-tyrosine deriving radioactivity, bound to nuclear DNA, is higher at low pH, (5.6) if compared to pH 6.8. The highest radioactivity bound to cell DNA is found during the transition from the amelanotic to the melanotic phenotype in human melanoma cell lines. As a control, the binding of ³H-L-tyrosine radioactivity to human prostate fibroblast DNA was investigated.     

恶性黑素瘤患者外周血酪氨酸酶与临床分期的相关性研究

使用逆转录聚合酶链反应（ＲＴ－ＰＣＲ）检测恶性黑素瘤患者外周血中酪氨酸酶ｍＲＮＡ,并与健康供血者和其它皮肤恶性肿瘤患者对照。结果：６８例恶性黑素瘤患者,临床Ⅰ期和Ⅱ期酪氨酸酶ｍＲＮＡ的ＲＴ－ＰＣＲ阳性率分别为６．５％和１３．３％,Ⅲ期为４２．９％,Ⅳ期（即有远距离转移者）为８７．５％（Ｐ＜０．００１）。说明外周血中酪氨酸酶ｍＲＮＡ阳性率与临床分期有明显的关系,而与性别、肿瘤发病部位和病理学分类无关（Ｐ＞０．０５）。在健康供血者和其他皮肤恶性肿瘤患者血液中酪氨酸酶ｍＲＮＡ的ＲＴ－ＰＣＲ均为阴性。提示酪氨酸酶ｍＲＮＡ具有特异性。     

复方中药含药血清对人A375黑素瘤细胞酪氨酸酶活性的影响

目的探讨复方中药含药血清对人A375黑素瘤细胞酪氨酸酶（TYR）活性的影响。方法体外培养人A375黑素瘤细胞,采用多巴速率氧化法研究复方中药含药血清对TYR活性的影响。结果低浓度（5%～10%）的Ⅰ方、Ⅱ方、Ⅲ方对酪氨酸酶活性无明显激活作用（P〉0.05）;高浓度（20%～30%）的Ⅰ方、Ⅲ方、Ⅵ方对TYR活性均有明显激活作用（P〈0.05）,以Ⅵ方作用最显著,且与其它各组相比,差异均有统计学意义（P〈0.01）。结论对TYR具有激活作用的中药组成复方并不一定对TYR有激活作用,具有祛风活血和补肾三重作用的Ⅵ方在促进TYR活性上优于祛风除湿Ⅰ方、养血活血Ⅱ方和滋补肝肾Ⅲ方。     

Isoprenylated phenolic compounds with tyrosinase inhibition from Morus nigra

A new isoprenylated sanggenon-type flavanone, nigrasin K (1), together with three known analogs (2–4) and five known Diels–Alder adducts (5–9), were isolated from the twigs of Morus nigra. Their structures were elucidated by spectroscopic methods. Sanggenon M (2), chalcomoracin (5), sorocein H (6), kuwanon J (7), sanggenon C (8), and sanggenon O (9) showed significant inhibitory effects on mushroom tyrosinase.