Ypsilandrosides C-G, five new spirostanol saponins from Ypsilandra thibetica

A further phytochemical investigation on the whole plants of Ypsilandra thibetica yielded one sapogenin and 12 spirostanol saponins. Five of these are new compounds, designated as ypsilandrosides C-G (2–6). Their structures were determined by detailed spectroscopic analysis, including extensive 1D and 2D NMR data, and by the result of a hydrolytic reaction. Compounds 2–5 were rare steroidal saponins that an apiofuranosyl unit was directly linked at C-3 of the aglycone. Selected spirostanol saponins (2–6, 9) were tested for their cytotoxic activities against K562, SPC-A-1, BGC-823, Eca-109, and AGS cell lines. Compounds 6 and 9 showed moderate inhibitory activity against all five cell lines. The antifungal properties of the new spirostanol saponins (2–6) against Candida albicans were also determined.     

Spirostanol tetraglycosides from Ypsilandra thibetica

Phytochemical reinvestigation on the whole plants of Ypsilandra thibetica obtained five new spirostane glycosides, ypsilandrosides H-L (1-5), and a known saponin polyphylloside III (6). Among them, 1 and 2 are the first spirostane glycosides which possess novel 5(6 → 7) abeo-steroidal aglycones. Compounds 3 and 4 are rare saponins whose aglycones contain a hydroxyl group at C-7. Their structures were elucidated on the basis of MS, 1D and 2D NMR spectroscopic analysis and chemical evidences. The isolated compounds were evaluated for their cytotoxic activity on five tumor cell lines.     

RNA沉默与植物病毒

植物中RNA沉默（RNAsilencing)亦称为转录后基因沉默（PTGS）或共抑制,是植物抵抗外来核酸（转座子、转基因或病毒）入侵,并保护自身基因组完整性的一种防御机制。RNA沉默是近十年来发现的植物界中普遍存在的现象,已成为植物分子生物学领域的一个新的研究方向。对RNA沉默特点和机制的研究表明,植物病毒与（转基因）植物内发生的RNA沉默有着密切的联系,作者从病毒对RNA沉默的诱导、抑制、防御等方面,简述了RNA沉默与病毒的关系。并对病毒载体所诱导的RNA沉默在植物发育和基因组功能分析等方面的应用价值进行了讨论。     

仙茅根茎中的配糖体

从仙茅（ Ｃｕｒｃｕｌｉｇｏ ｏｒｃｈｉｏｉｄｅｓＧａｅｒｔｎ） 根茎中分离到７ 个化合物, 经光谱分析推定其化学结构分别为： ２, ６ － 二甲氧基苯甲酸（Ａ） ; 苔黑酚葡萄糖甙（Ｂ） ; 仙茅素Ａ （Ｃ） ; 仙茅甙（Ｄ） ; ２４ｓ, ３β, １１α, １６β, ２４ － 四羟基环阿尔廷醇－ ３ － Ｏ－ α－ Ｌ－ 鼠李吡喃糖基（１ →２） － β－Ｄ－ 葡萄吡喃糖甙（Ｅ） ; ２４ｓ, ３β, １１α, １６β, ２４ － 四羟基环阿尔廷醇－ ３－ Ｏ－ β－ Ｄ－ 葡萄吡喃糖基（１ →２） － β－ Ｄ－ 葡萄吡喃糖甙（Ｆ） 和胡萝卜甙（Ｇ） 。Ｆ为一新甙。     

Steroidal saponins with antimicrobial activity from stems and leaves of Paris polyphylla var. yunnanensis

Rhizoma Paridis, the root of Paris polyphylla var. yunnanensis (Trilliaceae), is a Chinese traditional medicine, which resources become less and less. However, the aerial parts of this herb, which can regenerate every year, were discarded. In order to expand the resources, detailed chemical investigation on the stems and leaves of Paris polyphylla var. yunnanensis led to isolation of one sapogenin and 24 steroidal saponins (1-25), including 6 new glycosides, named chonglouosides SL-1-SL-6 (1-6). Their structures were elucidated on the basis of detailed analyses of their 1D and 2D NMR spectra and acid hydrolysis. Among them, compounds 3 and 4 are the first 23,27-dihydroxydiosgenin saponin having a sugar chain attached to C-23 or C-27, while compound 6 is the first 27-hydroxyruscogenin glycoside bearing 1, 27-di-O-sugar chains. The known compounds 10, 12, 14, 19, 20, 22, and 25 were isolated from the genus Paris for the first time. Antimicrobial testing activities of the selected compounds showed that compound 2, 3, 6, 8, 9, 11, 13, 17, 18, 21, and 24 were active against Propionibacterium acnes with MIC values of 62.5, 62.5, 3.9, 16.5, 17.2, 7.8, 39.0, 17.2, 31.3, 62.5, and 31.3μg/ml, respectively.     

Cytotoxicity of cardenolides and cardenolide glycosides from Asclepias curassavica

A new cardenolide, 12β,14β-dihydroxy-3β,19-epoxy-3α-methoxy-5α-card-20(22)-enolide (6), and a new doubly linked cardenolide glycoside, 12β-hydroxycalotropin (13), together with eleven known compounds, coroglaucigenin (1), 12β-hydroxycoroglaucigenin (2), calotropagenin (3), desglucouzarin (4), 6′-O-feruloyl-desglucouzarin (5), calotropin (7), uscharidin (8), asclepin (9), 16α-hydroxyasclepin (10), 16α-acetoxycalotropin (11), and 16α-acetoxyasclepin (12), were isolated from the aerial part of ornamental milkweed, Asclepias curassavica and chemically elucidated through spectral analyses. All the isolates were evaluated for their cytotoxic activity against HepG2 and Raji cell lines. The results showed that asclepin (9) had the strongest cytotoxic activity with an IC₅₀ value of 0.02 μM against the two cancer cell lines and the new compound 13 had significant cytotoxic activity with IC₅₀ values of 0.69 and 1.46 μM, respectively.     

烟草环斑病毒外壳蛋白基因的原核表达及抗血清的制备

烟草环斑病毒(Tobacco ringspot virus,TRSV)是我国二类进境检疫危险性有害生物,对农业生产危害较大.本研究依据TRSV外壳蛋白基因cp序列设计合成了2条引物,通过RT PCR扩增得到长约1500bp的目的片段.将目的片段与质粒pET-22b(+)连接,构建了含TRSV cp基因的融合蛋白原核表达载体pETRSV-CP.序列分析表明,TRSV-SD1的cp基因全长1548bp,编码515个氨基酸与GenBank中其它TRSV分离物cp基因相比,核苷酸及推导的氨基酸序列同源性为90.7%～94.6%.将pETRSV-CP转入大肠杆菌,诱导表达.SDS-PAGE结果显示,表达的TRSV CP融合蛋白的相对分子质量约为58kDa.以此融合蛋白制备的抗血清的效价为1/1024,抗血清与TRSV具有良好的特异性反应.     

小叶红光树中的黄酮类化合物

小叶红光树 (Ｋｎｅｍａｇｌｏｂｕｌａｒｉａ (Ｌａｍｋ .)Ｗａｒｂ .)为肉豆蔻科红光树属植物 ,产云南省西双版纳、屏边、河口、盈江、沧源等地。对采自云南省西双版纳的小叶红光树的乙醇粗提物进行了活性筛选 ,结果表明具有抗ＰＡＦ活性 ,并具有对抗花生四烯酸和ＡＤＰ诱导能力。该植物的化学成分尚未见报道 ,为寻找其中的活性成分 ,对该植物进行了化学研究。现报道从小叶红光树地上部分分离获得的 5个黄酮类化合物 ,经1ＨＮＭＲ ,13 ＣＮＭＲ ,ＭＳ等波谱测定 ,确定了它们的结构 ,分别为 :山奈酚 (Ｋａｅｍｐｆｅｒｏｌ 1 ) ,山奈酚 - 3…