石香薷中化学成分的研究

从石香薷（Ｍｏｓｌａ ｃｈｉｎｅｎｓｉｓ Ｍａｘｉｍ ．）中分离到１０ 个化合物,经光谱分析、化学方法及与已知化合物对照,分别鉴定为：６－甲基三十三烷（１）、β－谷甾醇（２）、熊果酸（３）、５－羟基－６,７－二甲氧基黄酮（４）、５－羟基－６－甲基－７－Ｏ－β－Ｄ－吡喃木糖（３→１）－β－Ｄ－吡喃木糖双氢黄酮甙（５）、５,７－二羟基－４－甲氧基黄酮（６）、洋芹素（７）、山奈素－３－Ｏ－β－Ｄ－葡萄糖甙（８）、桑色素－７－Ｏ－β－Ｄ－葡萄糖甙（９）、鼠李柠檬素－３－Ｏ－β－Ｄ－芹糖（１→５）芹糖－４－Ｏ－β－Ｄ－葡萄糖甙（１０）。其中,化合物５和１０ 为新化合物     

黄射干的异黄酮类成分

从黄射干Ｉｒｉｓｔｅｃｔｏｒｕｍ的甲醇抽提物中分到５个异黄酮：鸢尾黄酮甲素（１）,鸢尾花素（２）,野鸢尾黄酮（３）,鸢尾黄酮（４）,鸢尾黄酮甙（５）。化合物（１）和（２）系首次从黄射干中分到。所有成分经详细光谱分析确定。     

栗柄金粉蕨的黄酮成分

从湖南省江华瑶族自治县产的栗柄金粉蕨（Ｏｎｙｃｈｉｕｍ ｌｕｃｉｄｕｍ）的地上部分分离得到４个黄酮化合物,经光谱鉴定为：木犀草素－７－葡粮甙（１）,３,７－二甲氧基槲皮黄素（２）,槲皮黄素－３－葡糖甙（３）和金粉蕨素（４）,均为首次从该植物中获得。     

藏药黑边假龙胆的化学研究

龙胆科植物黑边假龙胆（Ｇｅｎｔｉａｎｅｌｌａａｚｕｒｅａ（Ｂｕｎｇｅ）Ｈｏｌｕｂ）是治疗肝胆湿热的１种藏药,从西藏日喀则产的全草中分离得到９个化合物,其中１个Ｃ一甙黄酮,异荭草素（ｉｓｏｏｒｉｅｎｔｉｎ）;１个山酮甙,獐牙菜酚甙（ｓｗｅｒｔｉａｎｏｌｉｎ）;１个木质体甙,橄榄脂素４一Ｏ一β－Ｄ－葡萄糖甙（ｏｌｉｖｉｌ４一Ｏ一β一ｇｌｕｃｏｓｉｄｅ）;３个环烯醚萜甙,龙胆苦甙（ｇｅｎｔｉｏｐｉｃｒｏｓｉｄｅ）,獐牙菜甙（ｓｗｅｒｔｉａｍａｒｉｎ）和马钱子酸（ｌｏｇａｎｉｃａｃｉｄ）;１个三萜,齐敦果酸（ｌｏｅａｎｏｌｉｃａｃｉｄ）１个甾醇,β谷甾醇葡萄糖甙（ｄａｕｃｏｓｔｅｒｏｌ）以及１个长链脂肪醇,三十烷醇（ｎ一１一ｔｒｉａｃｏｎｔａｎｏｌ）。它们的结构通过光谱和化学的方法得到了鉴定。上述结果,从次生代谢产物的角度为假龙胆属在系统分类上与龙胆属和獐牙菜属有着密切的联系提供了旁证。     

德钦红景天的化学成分

从云南产德钦红景天Ｒｈｏｄｉｏｌａ ａｔｕｎｔｓｕｅｎｓｉｓ（Ｐｒａｅｇ．） Ｆｕ 的根及根茎中首次分离得到８ 个化合物。根据各项光谱数据及化学反应鉴定其中一个新黄酮甙的结构为３ , ５ , ７ , ８ － 四羟基－黄酮４′－ 氧－ α－ Ｌ－ 鼠李糖吡喃甙, 命名为德钦红景天甙（ｒｈｏｄｉｏｌａｔｕｎｔｏｓｉｄｅ, ２） , 另外７ 个已知化合物分别是草质素－ ８ － 甲醚（ｈｅｒｂａｃｅｔｉｎ － ８ － ｍｅｔｈｙｌｅｔｈｅｒ,１） , 槲皮素（ｑｕｅｒｃｅｔｉｎ ,３） , 芦丁（ｒｕｔｉｎ,４） , 酪醇（ｔｙｒｏｓｏｌ,５） , 红景天甙（ｓａｌｉｄｒｏｓｉｄｅ,６） , 没食子酸（ｇａｌｌｉｃ ａｃｉｄ,７） 和β－谷甾醇（ － ｓｉｔｏｓｔｅｒｏｌ,８） 。     

圆穗蓼中的新黄酮甙成分

从圆穗蓼（Ｐｏｌｙｇｏｎｕｍ ｓｐｈａｅｒｏｓｔａｃｈｙｕｍ Ｍｅｉｓｎ．）中分离得到２个新黄酮甙,经光谱分析和化学方法鉴定为：３＇－羟基－５,４＇－二甲氧基－６,７－二氧亚甲基黄酮－３－Ｏ－「β－Ｄ－吡喃木糖基（１→６）」－β－Ｄ－吡喃葡萄糖甙⑴和５,４＇－二甲氧基－３＇－异丙烯基乙酰基－６,７－二氧亚甲基黄酮－３－Ｏ－「β－Ｄ－吡喃木糖基（１→６）－β－Ｄ－吡喃葡萄糖甙⑵,分别命名为圆穗蓼素Ａ     

山海螺的化学成分研究

从药用植物册海螺（Ｃｏｄｏｎｏｐｓｉｓ Ｉａｎｃｅｏｌａｔａ）中分离得到４个化合物,分别鉴定为：莽草酸（ｓｈｉｋｉｍｉｃ ａｃｉｄ）⑴、顺丁烯二酸（ｓｕｃｃｉｎｉｃ ａｃｉｄ）⑵、丁香脂素（ｓｙｒｉｎｇａｒｓ８ｉｎｏｌ）⑶、鸢尾甙（ｔｅｃｔｏｒｉｄｉｎ）⑷、化合物１－４均为首次从该植物分得。     

神农香菊花的化学成分研究(Ⅱ)

对采自湖北神农架的神农香菊（Dendranthema indicum（L）Des Monl．vaY．aromaticum Q．H．LiuetS．F．Zhang var．nov．）的化学成分进行研究,从中分离到5个化合物,利用波谱分析技术和文献对照确定了其结构,分别鉴定为木犀草素（luteolin）,木犀黄酮甙（luteolin-7-O-β-glucopyranoside）,刺槐素甙（acacetin-7-rhamnosidgluoside）,1-单山萮酸甘油酯（glyceryl-1-monobehenate）,山萮酸（behenic acid）。     

喙果绞股蓝黄酮类化合物的分离及结构测定

从喙果绞股蓝（Ｇｙｎｏｓｔｅｍｍａ　ｙｉｘｉｎｇｅｎｓｅＣ．Ｙ．ＷｕｅｔＳ．Ｋ．Ｃｈｅｎ．）的茎叶分离到７种化合物：喙果黄素（ｙｉｘｉｎｇｅｎｓｉｎ）（Ｉ）、山奈酚（ｋａｅｍｐｆｅｒｏｌ）（Ｉ）、商陆素（ｏｍｂｕｉｎ）（Ⅲ）、商甙（ｏｍ－ｂｕｏｓｉｄｅ）（Ⅳ）、槲皮素（ｑｕｅｒｃｅｔｉｎ）（Ｖ）、异鼠李素（ｉｓｏｒｈａｍｎｅｔｉｎ）（Ⅵ）和硬脂酸（Ⅶ）。其中,喙果黄素为新的黄酮甙,通过光谱分析及化学反应鉴定为商陆素一３－Ｏ－β一Ｄ一葡萄糖成。     

水青树和昆栏树茎皮的化学成分

用化学和波谱分析方法从水青树（Ｔｅｔｒａｃｅｎｔｒｏｎ ｓｉｎｅｎｓｅ Ｏｌｉｖ．）茎皮中分离鉴定了５个化合物,分别为丁香甙（ｓｙｒｉｎｇａｎｉｄｅ）、儿茶素（ｃａｔｅｃｈｉｎ）、β－谷甾醇（β－ｓｉｔｏｓｔｅｒｏｌ）、胡萝卜甙（ｄａｕｃｏｓｔｅｒｏｌ）和白桦脂醇（ｂｅｔｕｌｉｎ）,均为从该种植物中首次分得。从昆栏树（Ｔｒｏｃｈｏｄｅｎｄｒｏｎ ａｒａｌｉｏｉｄｅ Ｓｉｅｂ．ｅｔＺｕｃｃ．）茎皮中     

Liquid chromatography-mass spectrometry method for the analysis of the anti-cancer agent capecitabine and its nucleoside metabolites in human plasma

A reversed-phase high-performance liquid chromatography method with electrospray ionization and mass spectral detection is described for the determination of capecitabine, 5'-deoxy-5-fluorocytidine and 5'-deoxy-5-fluorouridine in human plasma with 5-chloro-2'-deoxyuridine as the internal standard. An on-line sample clean-up procedure allows dilution of the plasma sample with the initial mobile phase. The linear dynamic range is 0.0500-10.0 microgram/ml for capecitabine, and 0.0500-25.0 microgram/ml for the metabolites, 5'-deoxy-5-fluorocytidine and 5'-deoxy-5-fluorouridine, respectively. This method has been used to analyze plasma samples from patients receiving capecitabine in combination with oxaliplatin.     

Rapid and sensitive high-performance liquid chromatographic analysis of halogenopyrimidines in plasma

Recent studies have stressed the need for individual adjustment of 5-fluorouracil (5-FU) dosage. Most of the techniques previously reported are not well adapted to routine application. We describe a sensitive, selective and simple HPLC technique under isocratic conditions for the quantitation of 5-FU and other halogenopyrimidines. The proportion of reagents and internal standard were optimised to allow the use of minitubes, particularly adapted to large series of plasma assays. High extraction yield, 75% for 5-FU and 90% for 5-bromouracil and 5-chlorouracil, was obtained using 1.2 ml isopropanol–ethyl acetate (15:85, v/v) following precipitation of plasma proteins with 300 mg ammonium sulfate. The mobile phase was 0.01 M phosphate buffer (pH 3.0). Uracil and 5-fluorouracil were fully resolved with Spherisorb ODS2 column. The limits of quantitation and detection in human plasma were 6 ng ml⁻¹ and 3 ng ml⁻¹, respectively, for all compounds studied. The total analysis time required for each run was 25 min. Final results could be given within 90 min of blood sampling. At least 50 plasma samples could be analysed per day. This method has been successfully used for monitoring 5-FU-based treatments.     

The reversion of trp frameshift mutations in mut,polA, lig and dnaE mutant strains of Escherichia coli

Mutator mutations mutL25, mutR34, and mutU4 had similar effects on the reversion of 4 trp frameshift mutations of known sequence. The mutation trpE9777, which resulted from the addition of an A–T base-pair to a run of 5 A–T base-pairs, was most strongly reverted by the 4 mutators. Reversion of trpE9777 was also increased by mutation polA1 (DNA polymerase I) and dnaE486 and dnaE511 (DNA polymerase III). No effect was found with the ligase mutations, lig-4 or lig-ts7. Mutations polAex1 and polA107, both deficient in the 5′ → 3′ exonuclease activity of DNA polymerase I, had different mutator effects; the factor increase in reversion of trpE9777 was 28-fold for polAex1, 6-fold for polA107, and 21-fold for polA1. The trpE9777 mutation is a useful indicator of frameshift mutator activity.     

Automated determination of 5-fluorouracil and its metabolite in urine by high-performance liquid chromatography with column switching

We report a quantitative assay of 5-fluorouracil (FU) and its metabolite, 5-fluorodihydrouracil (FDHU) in human urine by used a column-switching high-performance liquid chromatographic method. The analyses were carried out using a molecular exclusion column for sample purification, and a cation-exchange column for separation. Each sample required only 40 min to analyze, and required no preparation other than filtration. Linearity was verified up to 1000 nmol/ml (r>0.993). The recovery of FU was 96–101%; recovery of FDHU was 96–105%. The imprecision (RSD) for FU (10–100 nmol/ml) was <1.5%, same-day (n=5), and <1.8%, day-to-day (n=5). The imprecision (RSD) for FDHU (10–100 nmol/ml) was <3.2%, same-day (n=5), and <4.0%, day-to-day (n=5). The detection limits were, respectively, 0.1 nmol/ml. We measured FU and FDHU in urine of seven cancer patients after oral administration of FU. The cumulative quantity ratio of the FDHU and FU (FDHU/FU) excreted in their urine within 120 min after FU administration was a constant value in all seven patients. Based on these results, we believe that our method provides a useful tool for evaluating FU metabolism.     

Loss of reiterated DNA sequences during serial passage of human diploid fibroblasts

A specific family of tandemly repeated DNA sequences was found to diminish in the human genome after serial passage of three strains of diploid fibroblasts. Eco RI restriction fragments of 340 and 680 bp were significantly reduced in quantity at late passage as determined by autoradiography of 14C-DNA and also by ethidium bromide fluorescence. The reduction in these closely related DNA sequences was confirmed by saturation hybridization to excess 14H-RNA transcribed from a homogeneous restriction fragment recleaved from the 340 bp DNA. The maximal fraction of DNA hybridizing to the 3H-RNA probe declined by 33-50% over 21-41 population doublings. Divergence and/or methylation of such sequences could not account for these results since the thermal stability of cRNA:DNA duplexes actually increased by 0.3 degrees C at late passage. Total highly repetitive sequences assayed by reassociation kinetics were also substantially reduced at late passage, implying that depletion may be common to many repeat families in DNA. The denaturation temperature for such rapidly reassociated duplexes again increased slightly at late passage, possibly reflecting the minor decreases in DNA methylation which were detected in two of the cell strains. Karyotype analyses demonstrated that over 95% euploidy was maintained, with no specific chromosome loss and no visible deletions at late passage. The depletion of reiterated sequences during repeated cell division is thus attributed to numerous small DNA deletions, which may arise from unequal recombination coupled with selection or from a nonreciprocal mechanism such as excision.     

Adenovirus DNA replication in vitro: Origin and direction of daughter strand synthesis

We have characterized a soluble enzyme system from adenovirus-infected cells that is capable of replicating exogenously added adenovirus DNA in vitro. Maximal DNA synthesis is observed when DNA-protein complex, isolated from purified adenovirus virions, is added as template. Under these conditions DNA replication starts at or near either end of the template. Daughter strand synthesis then proceeds in the 5′ to 3′ direction displacing the parental strand of the same polarity. Thus, the r daughter strand is synthesized from right to left on the conventional map of the adenovirus genome, and the l daughter strand is synthesized from left to right. This course of events is the same as that which occurs during adenovirus DNA replication in vivo. In contrast, when deproteinized adenovirus DNA is added to the in vitro system, the limited DNA synthesis that is observed appears to be due to a repair-like reaction. In particular, synthesis can begin at many sites within the template, and the synthetic product consists largely of short DNA chains that are covalently linked to template DNA strands.     

Functionally important residues in the peptidyl-prolyl isomerase Pin1 revealed by unigenic evolution

Pin1 is a phosphorylation-dependent member of the parvulin family of peptidyl-prolyl isomerases exhibiting functional conservation between yeast and man. To perform an unbiased analysis of the regions of Pin1 essential for its functions, we generated libraries of randomly mutated forms of the human Pin1 cDNA and identified functional Pin1 alleles by their ability to complement the Pin1 homolog Ess1 in Saccharomyces cerevisiae. We isolated an extensive collection of functional mutant Pin1 clones harboring a total of 356 amino acid substitutions. Surprisingly, many residues previously thought to be critical in Pin1 were found to be altered in this collection of functional mutants. In fact, only 17 residues were completely conserved in these mutants and in Pin1 sequences from other eukaryotic organisms, with only two of these conserved residues located within the WW domain of Pin1. Examination of invariant residues provided new insights regarding a phosphate-binding loop that distinguishes a phosphorylation-dependent peptidyl-prolyl isomerase such as Pin1 from other parvulins. In addition, these studies led to an investigation of residues involved in catalysis including C113 that was previously implicated as the catalytic nucleophile. We demonstrate that substitution of C113 with D does not compromise Pin1 function in vivo nor does this substitution abolish catalytic activity in purified recombinant Pin1. These findings are consistent with the prospect that the function of residue 113 may not be that of a nucleophile, thus raising questions about the model of nucleophilic catalysis. Accordingly, an alternative catalytic mechanism for Pin1 is postulated.     

Metabolism to methionine and growth stimulation by 5'-methylthioadenosine and 5'-methylthioinosine in mammalian cells

Viable human and murine lymphoblasts, and normal human tissue extracts, converted the thioether nucleosides 5'-methylthioadenosine (MeSAdo) and 5'-methylthioinosine (MeSIno) to methionine. Both MeSAdo and MeSIno, but not homocysteine, supported the short-term growth of human or murine lymphoblasts in methionine deficient medium. However, MeSAdo at concentrations greater than 25 microM inhibited cell growth. MeSIno was non-toxic at concentrations up to 200 microM, and supported the long-term growth of lymphoblasts in methionine-free medium.     

Implantable encapsulated cytosine deaminase having 5-fluorocytosine-deaminating activity

A cell extract of Escherichia coli was found to contain a cytosine deaminase that can stoichiometrically deaminate 5-fluorocytosine to 5-fluorouracil. It was partially purified and aseptically encapsulated in semipermeable cellulose tubes. These capsules, each containing 0.20 U, were implanted under the skin of rats. After a month the capsules were taken out, and found to contain 0.025 ± 0.011 U per capsule (half-life of 10 ± 2 days) (mean ± S.D., n = 6).This fact provided us with an idea for a new approach to the chemotherapy of cancer with the combined use of 5-fluorocytosine administered orally and cytosine deaminase capsule implanted locally.