【作者】 张国建；

【导师】 顾谦群；

【作者基本信息】 中国海洋大学 ， 药物化学， 2011， 博士

【摘要】 真菌生物体内存在着聚酮、聚异戊二烯、非核糖体多肽、莽草酸等多种生物合成途径。不同生物合成途径杂合偶联,再次重组,则形成杂合途径。由杂合途径产生的化合物称之为混合生源代谢产物,混合生源萜(混源萜)是其中的一类,其广泛存在于真菌、海洋无脊椎动物以及高等植物中,该类化合物是由异戊二烯途径与其它途径的偶联重组生成的。真菌来源的混源萜类化合物具有抗菌、免疫调节、植物毒素、真菌毒素、杀虫等多种生物活性,因此,对于该类化合物的研究倍受关注。本论文选定实验室菌株资源库中保藏的两株具有生产混源萜类化合物能力的海洋真菌菌株裸孢壳菌Emericella nidulans (HK-ZJ)和链格孢菌Alternaria sp. (JJY-32),对其进行次级代谢产物的研究。首先运用萃取,薄层色谱,正相、反相硅胶柱色谱,LH-20凝胶柱色谱,反相高压液相等化学分离纯化手段从E. nidulans (HK-ZJ)中共分离得到单体化合物20个(1-20),其中混源萜类化合物13个(4-16),包括6个新颖的异吲哚酮-法尼基类混源萜emeriphenolicins A-F (4-9)和7个austin类混源萜(10-16),与此同时我们还分离得到了3个新颖的异吲哚酮类化合物emerimidine A-C (1-3)。实验室在前期对菌株JJY-32次级代谢产物研究工作中获得9个结构新颖的混原萜类化合物(21-29),在本论文工作中我们引用OSMAC研究策略,对活性菌株JJY-32进行混源萜类次级代谢产物多样性开发。通过改变培养基条件,获得了14个alternarene混源萜类化合物,其中新化合物8个,分别为tricloalternarene A-G (30-36)和tricloalternarene H (38);通过酶抑制剂邻菲罗啉的添加扰动了alternarene的混合生物合成,再次获得了3个新颖的alternarene类混源萜monocloalternarene A-C (44-46)。采用二维NOESY、CD、构象分析以及化学衍生化等相结合的方法确定了骨架新颖的二环(21-24、26-27)、螺环(25)以及三环(30) alternarenes混源萜类化合物的绝对构型,并进一步推测了该系列混源萜类化合物(21-46)的生源关系以及骨架转化中可能存在的立体化学;采用添加酶抑制剂以及化学中间体的方法确定了JJY-32中alternarenes混源萜类化合物的生物合成起源于莽草酸途径和聚异戊二烯途径的混合途径。以H1N1病毒感染狗肾上皮细胞(MDCK)模型采用细胞病变抑制效应(CPE)分析方法评价了化合物1-9的抗病毒活性,发现异吲哚酮衍生物1-3具有中等强度的协助宿主细胞抵抗病毒侵染活性,IC50值分别为42.07、62.05和60.18μM;采用海虾致死模型评价austin类混源萜10-16的杀虫活性,发现化合物10、13-15对海虾(Artemia salina)表现出了不同程度的致死活性,特别是化合物14对海虾的半数致死浓度达到了7.2 ppm。利用LPS诱导RAW264.7细胞表达炎症因子模型,MALP-2诱导巨噬细胞和239T表达TLR受体模型等炎症模型,采用ELISA、RT-PCR、Western Blot、激光共聚焦显微镜等检测方法对alternarene混源萜类化合物37进行分子靶点水平的抗炎活性评价。发现其能阻断TLR/MyD88/NF-κB通路中P38和Akt蛋白的磷酸化激活,进而抑制通路中NO, IL-1β和IL-6等各种炎症因子的表达来发挥抗炎作用。利用NF-κB荧光素酶报告基因(NF-κB-luc)质粒转染肝癌细胞HT29模型以化合物37为参照,对比评价了其它alternarenes混源萜类化合物的抗炎活性。在相同的浓度条件下(100μmol/L),新化合物33和34均表现出了高于化合物37的活性,新化合物31-32以及已知化合物39、41-42表现出了与化合物37相当的抗炎活性。综上所述,本文对两株海洋来源的真菌次级代谢产物进行了系统的研究,得到emeriphenolicins类、austin类和alternarenes类共计30个混源萜化合物,其中新化合物17个,化合物45-46具有天然罕见的环己烯酮-法尼基骨架结构;并利用二维NOESY、CD、构象分析以及化学衍生化等相结合的方法确定了骨架新颖的多手性中心的二环及三环alternarenes类化合物的绝对构型;采用添加酶抑制的以及中间体互补的方法推测了alternarenes类混源萜的生物合成过程;发现了alternarenes类混源萜能够通过阻断TLR/MyD88/NF-κB通路而发挥抗炎作用,为新型抗炎药物的研究提供了部分科学依据。更多还原

【Abstract】 Analyses of the fungal model strain Aspergillus. nidulans genome revealed that fungi have many secondary metabolism pathways including polyketide biosythetic pathway (PKS), isoprene pathway, nonribosomal peptiede biosynthetic pathway (NRPS), shikimate pathway and other multiple biosynthetic pathways. Compounds that generated from mixed biosynthetic pathways were termed as hybrid origin products. Meroterpenoid is a class of natural products which are partially derived from isoprene pathway. Meroterpenoids produced by fungi showed a broad distribution of biological activities grouped into a variety of areas such as antimicrobial, antiviral, antitumoral, immunomodulatory, enzyme inhibitors and activators, phytotoxins, mycotoxins and antiinsect.The present work on the chemical investigation of two marine-derived bioactive fungal strains Emericella nidulans (HK-ZJ) and Alternaria sp.JJY-32 leads to 30 meroterpenoids, which can be sub-classified into three groups: isoindolone- farnesyls, austin-like meroterpenoids and alternarenes.A large scale fermentation of E. nidulans (HK-ZJ) was performed and the crude organic solvent extract was subjected to silica gel column, Sephadex LH20, PHPLC and etc to yield 20 compounds including six new isoindolone- farnesyls (4-9), seven astin-like meroterpenoids (10-16), three new isoindolones (1-3), two xanthones (17-18) and two dimethyldiphenyl ethers (19-20).Fermented under the origin culture condition, Alternaria sp.JJY-32 have been proved to produce 9 novel alternarenes and in the present work , by means of applying the OSMAC (One Strain Many Compounds) method, the meroterpenoid production capacity of Alternaria sp.JJY-32 was developed and potentialized. through manipulating culture medium components and addition of enzyme inhibitor, the secondary metabolites profile of Alternaria sp.JJY-32 was drastically shifted and resulted in another 11 new alternarenes (30-36, 38 and 44-46). Additionally, compounds 44 and 45 shared a natural rare skeleton of cyclohexenone ring beard with a triprenyl group.The stereochemistry of the monocyclo- alternarenes (45-56), bicyclo-alternarenes (21-24, 26-27), tricyclo- alternarenes (30-33) and sipro-tricyclo- alternarene (25) were investigated by means of 2-D NOESY experiment, CD method, conformational analysis as well as approach of chemical derivation. Further more, the biogenetic relationships and the stereochemistry of the skeleton transformation among the alternarenes were rationally proposed on the basis of their planar and stereochemical structure.Compounds 1-8 were tested for in vitro activity against H1N1 replication in MDCK cells. However, only compounds 1-3 showed moderate inhibitory effects with IC50 values of 42.07μg/mL and 62.05μg/mL (ribavirin as a positive control, IC50 24.60μg/mL). Compouns10-16 were experimentally confirmed to have obvious lethal toxicity to brine shrimp and especially for compound 14, the IC50 was 7.2 ppm.Using LPS-induced RAW264.7 cell activation and MALP-2 induced macrophages and 293T cells expressing TLR receptor as model systems, the molecular mechanism of anti-inflammatory activity exhibited by compound 37 has been demonstrated. The data indicate that anti-inflammatory properties of 37 resulted from the inhibition of proinflammatory cytokines and enzymes production via TLR2/MyD88/NF-κB signaling pathway.with compound 37 as a control, the anti-inflammatory activities of compounds 25, 28, 30-34, 38-39 and 41-42 were also evaluated by NF-κB-luciferase reporter gene transfect 293T cells model. Compounds 31-34, 39, and 41-42 exhibited the equal activities to compound 37 at the same concentration of 100μmol/L.In this study, 30 metroterpenods were isolated and identified from two marie-derived fungal strains E. nidulans (HK-ZJ) and Alternaria sp.JJY-32. Among them, 17 compounds were identified as new ones and the possible biogenetic pathways of the alternarenes (30-46) were given on the basis of their planar and stereochemical structure. Furthermore, a series of new compounds with anti-inflammatory activities were discovered, which to some extent enlighten the developing of new drug for curing diseases such as asthma, SLE and rheumatoid arthritis.更多还原