Two new saponins from the aerial part of Astragalus membranaceus var. mongholicus

Two new saponins named mongholicoside A (1) and mongholicoside B (2) were isolated from the aerial part of Astragalus membranaceus var. mongholicus. Their structures were determined by 1D and 2D NMR, ESI-MS techniques and chemical methods.     

Two novel tricyclic diterpenoids from Isodon rubescens var. taihangensis

Two novel tricyclic diterpenoids rubescensins U (1) and V (2) were isolated from the leaves of Isodon rubescens var. taihangensis. They were elucidated as a 8,15-seco-ent-kauranoid and an ent-abietanoid, respectively, by 1D and 2D NMR spectra, and single crystal X-ray analysis. Compound 1 is the first example of an 8,15-seco-ent-kaurane from the plants genus Isodon. A discussion of their biogenesis is described.     

Three new C_(19)-diterpenoid alkaloids from Delphinium laxicymosum var. pilostachyum

Three new lycoctonine-type C19-diterpenoid alkaloids, laxicymine 1, laxicymisine 2, and laxicyminine 3 have been isolated from the whole herb of Delphinium laxicymosum var. pilostachyum W.T. Wang. Their structures were established by spectra data.     

气相-质谱分析北细辛根和根茎中的挥发性成分

 采用 质谱联用技术对北细辛根和根茎的挥发性成分进行分离分析 ,鉴定出了 36种化学成分 ,主要成分为十五烷、甲基丁香酚、黄樟醚、3 ,5 二甲氧基甲苯等。对照北细辛根和根茎的分析结果可以发现 ,两者的挥发性成分基本相同 ,但含量有较大差异 ,这为北细辛的临床合理用药及质量控制标准的确定提供了实验依据。     

Three Novel Terpenoids from Schisandra pubescens var. pubinervis

Three new terpenoids, pubinernoids A–C ( 1 – 3 ), together with six known sesquiterpenoids, were isolated from the leaves and stems of Schisandra pubescens var. pubinervis. The structures of the new compounds were established on the basis of extensive spectroscopic analyses, including application of 2D‐NMR spectroscopic techniques. A plausible formation of the sesquiterpenoid 2 is proposed (Scheme 2), starting from guaianediol ( 4 ) as the biogenetic precursor, which was also present in the extract.     

Three Novel Bicyclic Taxoids from the Needles of the Chinensis yew, Taxus chinensis var mairei

PhytochemicalinvestigationontheneedlesofTaxuschinensisvar.mairei.resultedintheisolati=?nofthreenewbicyclictaxoids1--3alongwithtaxachitrieneA4'.Compoundl,lal, 14.5(c0.001,CHCI,),wasisolatedasacolorlessgummysubstance.TheiRspectrumshowedtheacetoxyanda,0-unsaturatedcarbonylsystembandsat1730and1650cm-l.HR-FAB-MSanalysisatm/z847.3152establishedthequasi-molecularforn'ulaasC.,H,=O.,Na([M Na] ,A(B-0.1mmu).ItsIH-NMRspectrum(Tablel)showedthecharacteristicsignalsoffourtertiarymethylgroupsoftaxo…     

A Unique Indolo‐[1,7]naphthyridine Alkaloid from Incarvillea mairei var. grandiflora (Wehrh.) Grierson

A novel alkaloid with a unique indolo‐[1,7]naphthyridine nucleus, incargranine B, was isolated from the whole plant of Incarvillea mairei var. grandiflora (Wehrh.) Grierson . Its structure was determined by means of spectroscopic methods.     

Analysis of self‐repair mechanisms of Phaseolus vulgaris var. saxa using near‐infrared surface‐enhanced Raman spectroscopy

We used surface‐enhanced Raman spectroscopy (SERS) to investigate ultrastructural changes in cell‐wall composition during the self‐repair of lacerated hypocotyls of Phaseolus vulgaris var. saxa. A detailed study of self‐repair mechanisms requires localized information about cell‐wall structure and morphology in addition to the chemical cell‐wall composition. Characteristic Raman and SER spectra yielded two‐dimensional maps of cross sections of P. vulgaris var. saxa visualizing chemical compositions in the walls of different cell types and during various repair phases. SERS substrate particles were produced by the reduction of gold chloride on the plant tissue surface and characterized with absorption spectroscopy, scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. The SERS results were compared with stained cross sections of the same plant using dark‐field microscopy with focus on lignin and suberin contents in repairing cells. In addition, SERS measurements revealed Au cyanide compounds on the cell surface, indicating the formation of hydrogen cyanide during the self‐repair phase. Copyright © 2009 John Wiley & Sons, Ltd.     

Monomer insertion mechanism of ring-opening polymerization of -caprolactone with yttrium alkoxide intermediate: A DFT study

The mechanism of -caprolactone (CL) insertion into a Y–OCH₃ bond was investigated using density functional theory (DFT) calculations. The optimized geometries and corresponding Gibbs-free energies of the intermediates were obtained, which confirmed a four-step coordination-insertion mechanism. The coordination of CL onto yttrium center led to a nucleophilic addition of the carbonyl group of CL, followed by an intramolecular alkoxide ligand exchange. A monomer insertion was completed by the CL ring opening via acyl–oxygen bond cleavage. The formation of the five-coordinated yttrium intermediate, 3, was found to be the rate-determining step. This study could be applicable to ring-opening polymerisation (ROP) of CL initiated by lanthanide metal complexes.     

Trichiol and 3-epitrichiol acetate, novel cytotoxic sterols with an unprecedented 2,6-dioxabicyclo[2.2.2]octan-3-one ring system from the myxomycete Trichia favoginea var. persimilis

Trichiol (1) and 3-epitrichiol acetate (2), two new sterols, have been isolated from field-collected fruit bodies of the myxomycete, Trichia favoginea var. persimilis, and their structures elucidated by spectral data. Trichiol (1) and 3-epitrichiol acetate (2) possess an unprecedented 2,6-dioxabicyclo[2.2.2]octan-3-one ring system. Trichiol (1) was cytotoxic against HeLa cells, while compound 2 proved to exhibit reversal effect against TNF-related apoptosis inducing ligand (TRAIL)-resistant Jurkat cell lines.