【作者】 谢春锋；

【导师】 娄红祥；

【作者基本信息】 山东大学 ， 药物化学， 2009， 博士

【摘要】 苔藓植物包括藓纲（Musci）、苔纲（Hepaticae）和角苔纲（Anthocerota）三类植物,在系统发育学上位于藻类和蕨类植物之间。尽管在植物进化谱上处于较低的位置,近年来从苔藓植物中分离获得了大量结构新颖且活性显著的萜类化合物和芳香族化合物,其中许多可作为新药研究的良好先导化合物。对苔类植物活性成分的研究表明苔类植物是生物活性天然产物的重要来源。开环双联苄化合物是苔类植物中的典型成分,具有多种生物学活性,为解决其化学多样性低及天然获取量少等问题,有必要对其生物合成进行研究。另外大环双联苄化合物因为大环的高度扭曲,目前已经被视为光学活性奇特的分子,深入研究其立体化学特征,对理解这类天然产物的药理活性作用机制和生物合成均具有重要的意义。本文对毛地钱（Dumortiera hirsute）乙醚提取物进行系统的化学成分研究,共分离鉴定7个化合物,为该植物的化学分类和化学生态学研究提供了依据。其中dumhirone A（1）为一新颖的环己二烯酮衍生物,3,4-O异亚丙基莽草酸（2）为新天然产物。本文对无纹紫背苔（Plagiochiasma intermedium）乙醚提取物进行系统的化学成分研究,共分离鉴定10个化合物,包括7个大环双联苄化合物（8-14）和2个苯甲醛衍生物（15,16）。化合物riccardin C（13）对白色念珠菌的敏感株和耐药株具有相同的抗真菌作用,MIC值均为32μg/mL,同时具有较好的耐药逆转活性,对氟康唑的最大逆转倍数为256,亦发现化合物13（浓度为100μg/ml）对13株临床白色念珠菌菌株的成熟生物被膜具有较强的杀伤能力（杀伤率为95.09%-98.93%）。另外双联苄化合物8-13对人白血病细胞K562均表现出中等的生长抑制活性(IC₅₀为12.0至25.5μM)。最后发现无纹紫背苔中的挥发油具有抑制植物致病菌生长的能力,在1024μg/ml的浓度时几乎完全抑制了尖镰孢（Fusarium oxysporum f.sp.lycopersici）的菌丝生长,在一定程度上阐述了苔类植物挥发油的生态学意义。本文对多苞裂萼苔（Chiloscyphus polyanthus）的乙醇提取物进行了化学成分研究,共分离获得5个化合物,采用波谱法对其进行结构鉴定,包括2个对映-贝壳杉烷（ent-kaurane）二帖:对映-贝壳杉烷-7α,11β,14β-三醇-15-酮（17）和11α-羟基-对映-贝壳杉-16-烯-15-（18）,1个桉烷内酯:11（13）-二氢特勒内酯[11（13）-dihydrotelekin;5β-hydroxy-eudesman-4（15）-en-12,8β-olide]（19）,一个多元醇:甘露醇（mannitol）（20）。其中化合物17为新贝壳杉烷二帖,18-19为首次从该植物中分离得到。化合物19（浓度为100μg/ml）具有白色念珠菌菌丝生长抑制的活性,为一新型的菌丝延长特异抑制剂。本文以苦瓜粗酶为生物催化剂,将底物二氢白藜芦醇转化为6个以C-C、C-O-C和C-CH₂-C连接的新开环双联苄（21-26）。其中化合物23和25为新型开环双联苄,未从植物中分得该类型化合物。与底物相比,化合物22和26对人前列腺癌PC3细胞株显示较强的细胞毒活性,其IC₅₀值分别为14.2和16.6μM。本文最后利用HPLC-CD、VCD以及定量化学计算等方法,对以两个醚桥连接的双联苄marchantin E和以醚桥和C-C键连接的双联苄riccardin D立体化学进行了系统研究。从marchantin E中拆分得到两个立体异构体,通过对比实验CD谱和理论CD谱[ZINDO/S-CI和TDDFT（B3LYP/TZVP）水平],确定两个立体异构体的绝对构型为S-marchantin E和R-marchantin E;从riccardin D中拆分得到两个半稳定的阻转异构体,基于立体元素分析、构象分析和分子动力学模拟方法,确定riccardin D中的联苯轴C-C键为半稳定轴,能垒计算为114.97 kJ/mol,最后通过比较实验CD、VCD谱和理论CD、VCD谱,确定两个半稳定阻转异构体的绝对构型为M-riccardin D和P-riccardin D。更多还原

【Abstract】 The bryophytes[Musci（mosses）,Marchantiophyta（liverworts） and Anthocerotae （hornworts）],are morphologically placed between the algae and the pteridophytes（fern）. Although they are located at the low position on evolutionary scale,various types of lipophilic terpenoids and aromatic compounds,which show significant biological activities,are isolated from the bryophytes in the past decades.Now the bryophytes have been well know as a source of biologically active,naturally occurring compounds. Bisbibenzyls,a class of characteristic components derived from liverworts,are attracting more and more attention because of their wide range of biological significance.Due to limited availability and poor structural diversity among natural acyclic bisbibenzyls,it is necessary to biosynthesize them for detailed pharmacological studies.In addition,macrocyclic bisbibenzyls have been recognized as a novel class of stereochemically intriguing molecules due to the highly strained cyclic structures.It is important to perform detailed studies on the bisbibenzyl stereochemistry for understanding their biosynthesis and mechanism of pharmacological action.Seven compounds were isolated from the ethyl ether extract of Dumortiera hirsute, which shed lights on chemotaxonomy and chemical ecology of this liverwort species. Among the compounds,dumhirone A（1） was a new phenylethyl cyclohexadienone derivative and 3,4 -O-isopropylideneshikimic acid（2） was a new natural product.Ten compounds were obtained from the ethyl ether extract of Plagiochiasma intermedium,including seven bisbibenzyls（8-14） and two benzaldehyde derivatives（15, 16）.Compound riccardin C（13） possessed the in vitro antifungal property against the fluconazole-sensitive and resistant strains of Candida albicans,with the same MIC of 32μg/mL.Furthermore,13 was demonstrated to act as a fungal resistance modifying agent when combined with fluconazole on three resistant strains of C.albicans.The MICs of fluconazole was dramatically reduced by at most 256-fold.Compound 13 was also toxic to mature biofilms of 13 clinical C.albicans strains（killing rate 95.09%-98.93%）.Finally,the P.intermedium essential oil showed inhibitory effects in vitro against the plant pathogenic fungus Fusarium oxysporum f.sp.lycopersici.Almost complete inhibition of mycelial growth was observed at 1024μg/ml concentration as compared to the control（full growth）.This may reveal the ecological role of the liverwort essential oil.Five compounds,including two ent-kaurane dipenoids ent-kauran-7α,11β, 14β-triol-15-one)（17） and 11α-hydroxy-ent-kaur-16-en-15-one（18）,and one eudesmanolide 11（13）-dihydrotelekin（19）,were isolated from the ethanol extract of Chiloscyphus polyanthus.Among them,compound 17 was a new ent-kaurane dipenoid. Compound 19（100μg/ml） was a specific inhibitor on hyphal elongation of C.albicans.Biotransformation of dihydroresveratrol by crude Momordica charantia peroxidase produced six new acyclic bisbibenzyls（21-26）.Their structures were established on the basis of NMR and MS analyses,which were C-C,C-O-C,and C-CH₂-C dimers of dihydroresveratrol.Compounds 23 and 25 are acyelic bisbibenzyls of new types not isolated from the plant kingdom previously.Compounds 21-26 were tested for antiproliferative activity against human prostate cancer PC3 cell line in vitro and compounds 22 and 26 were found to be more potent than the parent compound with IC₅₀ values of 14.2 and 16.6μM.The absolute stereochemistry of macrocyclic bisbibenzyls marchantin E and riccardin D were investigated in detail through HPLC-CD,VCD and computational methods.Two stereoisomers were resolved from marchantin E and their absolute configurations were determined by comparison of their experimental CD spectrum with those calculated for S-marchantin E and R-marchantin E.Two configurationally semistable atropisomers were resolved from riccardin D.the biaryl axis is semistable chiral element based on analysis of stereogenic elements,conformational analysis and molecular dynamics simulations.The rotational barriers were determined as 114.97 kJ/mol by computational method.The absolute configurations of these semistable atropisomers were assigned as M-riccardin D and P-riccardin D using a combination of electronic circular dichroism（ECD） and vibrational circular dichroism（VCD）.更多还原