中文摘要：

试验旨在研究新发现的两种牛蛙活性肽对人肺癌细胞NCFH446、人乳腺癌细胞MCF-7及小鼠白血病细胞K5623种肿瘤细胞体外增殖的影响，为新的多肽抗肿瘤药筛选提供依据。本试验利用圆二色谱（cD）法检测两种新牛蛙活性肽的二级结构，通过MTS细胞毒试验测定不同浓度的两种新牛蛙活性肽对人肺癌细胞NCI-H446、人乳腺癌细胞MCF-7及小鼠白血病细胞K5623种瘤细胞体外增殖的影响。圆二色谱法结果显示，Temporin-Lb的二级空间结构为聚脯氨酸Ⅱ型螺旋（PPⅡ）结构，Catesbeianin-1a的二级空间结构为无规则卷曲。MTS细胞毒试验结果显示，给予Catesbeianin-1a的3种瘤细胞培养24h后，瘤细胞形态无明显变化，正常增殖，而给予Tem—porin-Lb的3种瘤细胞培养24h后，瘤细胞发生皱缩、细胞变圆、脱落甚至死亡，增殖受到抑制，其中对Temporin-Lb在4-40μmol／L浓度范围内对小鼠白血病细胞K562的抑制效果最为明显。结果表明，新牛蛙活性肽Tempor—in-Lb具有一定的抑瘤作用，Catesbeianin-1a对瘤细胞的体外增殖没有明显影响。

英文摘要：

The study was aimed to research the growth inhibitory effects of two new bioactive pep- tides Temporin-Lb and Catesbeianin-la from Rana catesbeiana on human lung cancer NCI-H446 cells,breast cancer MCF-7 cells and mice leukemia K562 ceils,and provide the basis for selecting the new peptide antitumor drugs. The second structures of two bioactive peptides were tested by circular dichroism spectrum （CD）, and the effects of the two new bioactive peptides on human lung cancer NCI-H446 cells,breast cancer MCF-7 cells and mice leukemia K562 cells were exam- ined with MTS cytotoxicity assay. The circular dichroism spectrum results showed the secondary structure of Temporin-Lb was PP Ⅱ , and the secondary structure of Catesbeianin-1a was random coil. Using MTS cytotoxicity assay,it was found that given Catesbeianin-1a, the sharp of the three cancer ceils above had little changed after culturing for 24 h,and the three cancer ceils promoted normal. Given Temporin-Lb, the cell morphology of three cancer cells had changed after culturing for 24 h, the growth of the three cancer cells above had been inhibited, especially the bioactive peptide Temporin-Lb had a sharp antitumor effect to mice leukemia K562 cells between the coneentra-tion of 4 and 40μmol/L. Bioactive peptide Catesbeianin-la had no obvious effect on proliferation of the three cancer cells above. Bioactive peptide Temporin-Lb had a certain inhibitory effect to tumor cells.