第58届Intel ISEF中国参赛项目：我国东海微生物来源新型环二肽的分离鉴定、活性和作用机理的研
上海市延安中学 高二 焦姮
学科：生物化学
本研究的目的是从海洋微生物中筛选药用活性物质，并对其活性和作用机理进行研究，为开发海洋新药提供基础。通过对从我国东海筛选获得的一株活性芽孢杆菌进行发酵，活性化合物的分离、鉴定和体内外生物学活性分析，并开展了部分作用机理研究。实验从该微生物的发酵液中分离获得一个新型环二肽，其结构为3-甲基-6-（2-甲基丁基）哌嗪-2,5-二酮（中国发明专利申请号：200610029064.X）。该化合物具有显著的体外癌细胞杀伤活性和抗真菌活性以及体内抑瘤效应；新环二肽通过诱导癌细胞凋亡从而发挥抗肿瘤作用。通过本课题的研究，从海洋微生物中获得一个新型环二肽，有可能作为先导化合物开发成抗癌和抗真菌新药。
A Novel Cyclodipeptide with a Significant Anti-tumor Activity from a Marine Bacillus
Biochemistry
Jiao Heng 17, Shanghai Yan’an High School
A novel cyclodipeptide [3-methyl-6-(2-methylbutyl)-piperazine-2, 5-dione] was isolated from a marine bacillus in my previous works, and it showed a potent anti-fungal activity in vitro. The purpose of the present study is to identify its anti-tumor activity as well as the possible mechanisms involved in. Cytotoxicity was tested against tumor cell lines in vitro, tumor growth inhibition was observed on tumor-bearing mice model transplanted with S180 cells subcutaneously. The mechanisms on cellular apoptosis contributing to its anti-tumor activity were revealed by electronic microscopy, flow cytometry, DNA fragmentation, and caspases activation. The results showed the compound exhibited a significant cytotoxicity against tumor cells including P338, S180 and A1990 with the IC50 of 0.10, 0.98 and 5.20 microgram/ml respectively. It elicited also a strong anti-tumor activity in S180-bearing mice model in an ED50 of 49.14 microgram/kg. The anti-tumor effect of the compound was identified through the induction of the apoptosis in tumor cells. The typical appearances including chromatin condensation, mitochondrial swelling, and intracellular bulb formation were seen under the electronic microscopy. An apoptotic rate of 53.04% was achieved at the concentration of 2.0 microgram/l by flow cytometry with annexin V/PI double staining. NA fragmentation was detected obviously on DNA electrophoresis, and it was demonstrated that it was a potent activator for caspase 3, 7 and 8. Furthermore, the compound did not affect the behaviors and activities of our mice in the experiments at the dosage of 2000 microgram/kg (40-fold ED50). The novel cyclodipeptide may serve as a lead compound for further development of the novel anti-tumor agent.
