南极磷虾微生物中氟代天然产物的发现与活性研究

Natural products (NPs) are the inspiration or source of drug discovery. Fluorochemicals are the main form of drugs because of their strong efficacy, high metabolic stability and high bioavailability, which constitute 25% of the marketed drugs. Therefore, fluorinated natural products (FNPs) are of great reference value for the development of fluorine-containing drugs. However, due to the extremely low content of water-soluble fluorine that can be utilized in nature, and the difficulty to be oxidized by a halogenase to fluorine cations, FNPs are extremely rare and only nineteen FNPs were identified. We hypothesized that microorganisms living in high-fluorine habitats should be able to use fluorine to synthesize FNPs, and carried out related study. The previous study revealed that there were diverse symbiotic or epiphytic microorganisms in Euphausia superba with a high fluorine content. These microbes showed good tolerance to NaF and produce 19F NMR-positive NPs, which we called "FNPs-producing strains". Based on these findings, the diversity of microorganisms associated with E. superba and their chemo-ecological effects on the host will be further studied in this project. And the FNPs and other new bioactive NPs will be obtained by improvement of the ability of "FNPs-producing strains" to produce FNPs through host-induced and co-culture strategies. The results are expected to provide the lead structures for the discovery of fluorine-containing drugs, expand the new uses of E. superba, and provide a scientific basis for further study on the ecological function of microorganisms associated with Antarctic krill, E. superba.

天然产物是药物研究的启迪或泉源，氟代药物由于其药效强、代谢稳定性和生物利用度高而成为药物的主要形式,构成25%的上市药物，故氟代天然产物对氟代药物的研发具有重要参考价值。但由于自然界中可被利用的水溶性氟的含量极低、且不易被卤代酶氧化为氟正离子，氟代天然产物稀少，目前只有19个。申请者推测：生活在高氟环境中的微生物，能利用氟生产氟代天然产物（简称“产氟”）；并在前期研究中发现，氟含量极高的南极磷虾中存在丰富的共附生微生物，这些微生物表现出较好的NaF耐受性、产生19F NMR呈阳性的天然产物，即所谓“产氟菌株”。本项目拟在此基础上，进一步研究南极磷虾微生物的多样性及其对宿主的化学生态作用；通过宿主诱导、共培养等手段，提高南极磷虾微生物“产氟菌株”的“产氟”能力，获得氟代等新颖的活性天然产物。为氟代药物的研究提供先导结构，开拓南极磷虾新用途，亦为深入研究南极磷虾微生物的生态作用提供科学依据。

卤代特别是氟代化合物是创新药物的主要来源，但氟代天然产物很少。在该项基金(No. 41876172)的支持下，项目组研究人员经过4年的努力，通过南极磷虾中耐氟微生物的分离筛选、发酵优化和基因挖掘、耐氟机制及其代谢产物的分离鉴定，获得了46株真菌和34株细菌、142个化合物(包括56个新化合物、10个氟代产物、14个氯代产物和36个活性化合物)；活性化合物中16个具有肿瘤细胞毒活性、10个有抗菌活性、7个有抗H1N1甲型流感病毒活性、1个具有糖尿病相关的α-糖苷酶抑制活性、2个表现出阿尔兹海默病相关的Aβ蛋白抑制活性，为新药先导物的发现准备了化合物基础；初步阐明了南极磷虾真菌的耐氟机制是将细胞毒性的氟负离子代谢为低细胞毒性的四氟硼酸盐或细胞毒性更低的葡萄糖络合的二氟硼酸盐、并代谢产生具有协同耐氟作用的亚油酸等不饱和脂肪酸化合物，为深入探讨南极磷虾微生物在高氟环境中的生存提供了依据。上述研究成果目前已发表19篇SCI论文、获得了2件授权国家发明专利、毕业2名博士和4名硕士。