枇杷叶的化学成分

枇杷叶系蔷薇科（Rosaceae）枇杷属植物枇杷[Eriobotrya japonica（Thunb．）Lindl．]的干燥叶,为常用中药,收载于历版《中华人民共和国药典》中。枇杷叶归肺、胃经,具清肺止咳、降逆止呕的作用,用于治疗肺热咳嗽、气逆喘气、胃热呕逆及烦热口渴之症状。目前,已经从枇杷叶中分离出三萜酸、黄酮类、多酚、倍半萜及其苷类等成分,对其药效的研究主要集中在三萜酸的抗炎心、降血糖和抗病毒活性等方面。     

Two lignan dimers from bamboo stems (Phyllostachys edulis)

Phyllostadimers A and B, two bis-lignans in which the two lignan units are directly connected by a C-C bond, were isolated from stems of bamboo, Phyllostachys edulis. Their structures were determined on the basis of spectral evidence. In addition, 14 known compounds were also obtained throughout the investigation. Phyllostadimer A significantly inhibited liposomal lipid peroxidation.     

二苯乙烯苷通过抑制NF-κB的激活减轻MPP＋诱导的PC12细胞凋亡

目的：探讨2,3,5,4＇-四羟基二苯乙烯-2-o-β-D-葡萄糖苷（2,3,5,4＇-tetrahydroxystibene-2-o-β-D-glucoside,TSG）对1-甲基-4-苯基吡啶离子（1-methy-4-phenylpyridinium,MPP＋）诱导PC12细胞凋亡的影响及其可能机制。方法：四甲基偶氮唑蓝（MTT）比色试验检测PC12细胞活性;Hoechst33258染色法测定细胞凋亡;Westernblotting检测NF-κB（P65）和IκBα蛋白的表达。结果：MPP＋（300μmol/L）作用于PC12细胞24h后,与正常对照组比较,细胞存活率降低（53.3±3.4%）（P〈0.01）;细胞染色质固缩,细胞核呈致密浓染。TSG（1,5,10μmol/L）预处理24h后,细胞存活率增加（60.8±1.9%）,（70.1±1.8%）（P〈0.01）,（81.2±1.9%）（P〈0.01）;细胞核凝聚明显减少,且具有量一效关系。另外,MPP＋可使PC12细胞核中NF-κB（P65）蛋白表达升高,细胞浆中IκBα蛋白表达降低;与MPP＋处理组细胞相比,TSG预处理后,PC12细胞核中高表达的NF-κB（P65）蛋白水平明显降低,细胞浆中低表达的IκBα蛋白水平升高。结论：TSG对MPP＋诱导的PC12细胞凋亡具有浓度依赖性的抑制作用,其作用机制可能与抑制NF-κB的激活有关。     

Probing the structure of the Ff bacteriophage major coat protein transmembrane helix dimer by solution NMR

The transmembrane (TM) segment of the major coat protein from Ff bacteriophage has been extensively studied as an example of dimerization in detergent and lipid bilayer systems. However, almost all the information regarding this interaction has been gained through mutagenesis studies, with little direct structural information being available. To this end solution NMR has the potential to provide new insights into structure of the dimer. In order to evaluate the utility of this approach we have studied a selectively ¹⁵N-labeled peptide containing the TM segment of MCP (MCP_TM) by solution NMR. This peptide was found to give rise to detergent concentration-dependent spectra that were assigned to monomeric and dimeric forms. The standard free energy of this interaction in SDS was estimated from these spectra and found to be consistent with weak but specific dimerization. In addition, similar spectra could be obtained in β-octyl glucoside with intermolecular paramagnetic relaxation experiments demonstrating a parallel arrangement of TM helices in the dimer. In both detergents backbone chemical shift differences between monomeric and dimeric forms of MCP_TM showed that the largest changes occur around its GXXXG motif. The resulting structural model is consistent with observations made for MCP mutants previously characterized in biological membranes, opening the door to detailed structural characterization of this form of MCP. These results also have general implications for the study of weakly interacting TM segments by solution NMR since the use of similar sample conditions should allow structural data to be accessed for oligomeric states from a wide range systems that undergo biologically relevant but weak associations in the membrane.     

Two New Sesquiterpenoid Glucosides from the Aerial Parts of Saussurea involucrate

Two new sesqulterpenoid glucosides, namely α-hydroxycostic acid 6-β-D-glucopyranoside （compound 1） and 11 βH-11,13-dlhydrodehydrocostuslactone 8α-O-（6＇-acetyl）-β-D-glucopyranoside （compound 2）, along with 11 known sesqulterpenoids （compounds 3-13） were isolated from the aerial parts of Saussurea involucrate （Kar. et Kir.） Sch.- BIp. The structures of the new sesquiterpenoid glucosides were established by one- and two-dimensional nuclear magnetic resonance and mass spectrometry analysis.     

A glycosidic germacradienolide from Eupatorium altissimum

The isolation and structure determination of a glycosidic germacradienolide from Eupatorium altissimum are reported. Eupatorin and 5-hydroxy-3′,4′,6,7-tetramethoxyflavone were also found.     

Grayanoside C,a new diterpene glucoside from Leucothoe grayana

A new diterpene glucoside has been isolated from Leucothoe grayana. Its structure was elucidated by X-ray diffraction analysis of a dehydrated product of the aglycone and conversion of the same to leucothol A.     

New ellagitannin and galloyl esters of phenolic glycosides from sapwood of Quercus mongolica var. crispula (Japanese oak)

Two novel glycosides, 4,5-dimethoxy-3-hydroxyphenol 1-O-β-(6′-O-galloyl)-glucopyranoside (1) and (+)-2α-O-galloyl lyoniresinol 3α-O-β-d-xylopyranoside (2), as well as a novel ellagitannin named epiquisqualin B (3), were isolated from sapwood of Quercus mongolica var. crispula along with 19 known phenolic compounds. The structures of the novel compounds were elucidated on the basis of chemical and spectroscopic investigation. Compound 2 is the first example of a lignan galloyl ester, and 3 is the oxidation product of vescalagin, which is the major ellagitannin of this plant.     

Constituents of Chrysothamnus viscidiflorus

A phytochemical investigation of the aerial parts of Chrysothamnus viscidiflorus var. viscidiflorus afforded three new [chrysothol (1), 2 and 4] and seven known compounds, including five sesquiterpenes, two cinnamic acid derivatives, two ketoalcohol derivatives and one coumarin glucoside. The structures of two previously reported compounds, 1b and 1c, were revised on the basis of chemical reaction. Structures of the compounds were determined by extensive NMR studies, including DEPT, COSY, NOE, HMQC, HMBC and X-ray analysis. The unpublished X-ray data of the known compounds 6 and 7 are reported. Compounds chrysothol (1), and 8-10 showed anti-cancer activity against human breast cancer cells.     

Grevillosides A-F: glucosides of 5-alkylresorcinol derivatives from leaves of Grevillea robusta

From a MeOH extract of leaves of Grevillea robusta, seven compounds (1-7) were isolated. One known compound (7) was identified with a benzyl glucoside, icariside F₂. The structures of the six of these, named grevillosides A-F (1-6), were elucidated on detailed inspection of one- and two-dimensional NMR spectroscopic data as glucosides of 5-alkylresorcinols.