第58屆Intel ISEF中國參賽項目：我國東海微生物來源新型環(huán)二肽的分離鑒定、活性和作用機理的研
上海市延安中學 高二 焦姮
學科：生物化學
本研究的目的是從海洋微生物中篩選藥用活性物質(zhì)，并對其活性和作用機理進行研究，為開發(fā)海洋新藥提供基礎。通過對從我國東海篩選獲得的一株活性芽孢桿菌進行發(fā)酵，活性化合物的分離、鑒定和體內(nèi)外生物學活性分析，并開展了部分作用機理研究。實驗從該微生物的發(fā)酵液中分離獲得一個新型環(huán)二肽，其結構為3-甲基-6-（2-甲基丁基）哌嗪-2,5-二酮（中國發(fā)明專利申請?zhí)枺?00610029064.X）。該化合物具有顯著的體外癌細胞殺傷活性和抗真菌活性以及體內(nèi)抑瘤效應；新環(huán)二肽通過誘導癌細胞凋亡從而發(fā)揮抗腫瘤作用。通過本課題的研究，從海洋微生物中獲得一個新型環(huán)二肽，有可能作為先導化合物開發(fā)成抗癌和抗真菌新藥。
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.
