Synthesis of the Precursor of Tetrasaccharide from Laminin

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A Novel Oligosaccharide from the Mucus of the Loach

A novel oligosaccharide was isolated and purified from the mucus of the loach, Misgurnus anguillicaudatus. Its was identified by several qualitative tests and characterized by elementary analysis,UV and IR spectrum. Its average molecular weight(Mw=1539.4) was determined by gel permeation chromatography. The major structural monomers of Misgurnus anguillicaudatus oligosaccharide were identified to be D-galactose and L-fucose by paper chromatography and gas chromatography.     

Polyoxypregnanes from the stems of Marsdenia tenacissima

From the stems ofMarsdenia tenacissima two new polyoxypregnanes were isolated, their structures were elucidated by 1D, 2D-NMR as 11α,12β-di-O-tigloyl-tenacigenin B （1） and tenacigenoside E （2）.     

Xanthones from the bark of Garcinia Xanthochymus

Two novel xanthones, 1,6-dihydroxy-4,5-dimethoxyxanthone (1) and 1,5,6-trihydroxy-7,8-di(3-methyl-2-butenyl)-60,60- dimethylpyrano(20,30:3,4)xanthone (2) were isolated from the bark of Garcinia xanthochymus by normal phase and reverse phase silica gel column chromatography. Their structures were elucidated by spectroscopic methods, especially 2D-NMR techniques.     

Alkaloids from the Roots of Saccopetalum prolificum

In recent years, an increased interest in the phytochemistry of the Annonaceae has beensparked by the isolation of the antileukemic Annonaceous acetogenin'. Saccopela/umprolificllm (Chun el How) Tsiang (Allnonaceae) is an evergreen tree distributed inHainan Province, P. R. China. The ethanolic extract of the plant exhibited cell growthinhibitory activity (20 ig/ml) against LIZ10 lymphocytic leukemia. A new alkaloid,prolifine (l), was isolated from the roots of S. proldicum, in addition t…     

Estimation of spinodals from the density profile of the vapor–liquid interface

An extension of a recently proposed method for the calculation of the spinodals in pure fluid systems from the interfacial properties is elaborated, which requires the density profile as only input. The foundation of this approach is the so-called Fuchs-transformation which gives an estimate for the tangential pressure profile from the density profile. Using molecular dynamics simulation data for argon and carbon dioxide as well as lattice Boltzmann simulation data for the argon-like Shan–Chen fluid, the accuracy of the approach is analyzed. The Fuchs-transformation is qualitative, however it is possible to estimate the temperature–density projection of the spinodal. Depending on the underlying correlation function for the interfacial density profile reasonable results are obtained for the liquid and the vapor spinodal. The advantage of this method is that equilibrium data can be used to estimate the spinodal which is experimentally impossible to access because it is a highly non-equilibrium property. In the final consequence of this approach only the coexistence vapor and liquid densities are required to estimate the temperature–density projection of the spinodals.     

New Alkaloids from the Rhizomes of Goniothalamus Griffithii

GoniothalamusgrghthiiHook.F.etThoms(Annonaceae)isatropicalplantdistributedinsouthChina,IndiaandThailand.InwiderangescreeningfOrantitumoragentsfromAnnonaceaeplants,thecthanolicextractofrhizomesofG.grghthiiwasfOundtohc-..activeagainstvarioushumancancercelllines.Furtherpuriflcationoftheextractyieldedthreenewalkaloids,griffithdionel,griffiazanoneA2andgriffiazanoneB3wh()scstructuresweree1ucidatedbyvariousNMRtechniques,includingHMBC,NOEexperiments.(R)-and(S)-MTPAderivativeswerepreparedtod…     

Diastereoisomeric saponins from the rhizomes of Tupistra chinensis

A pair of diastereoisomeric furostanol saponins was obtained from the n-butanol fraction of methanol extract from Tupistra chinensis rhizomes,a folk medicine of Shennongjia Forest District of Hubei Province.Their structures were determined,on the basis of chemical and spectroscopic evidences.     

Indole Alkaloids from the Roots of Ervatamia hainanensis

Evratamia hainanensis Tsiang, is distributed in the mountain and forest regions of 100-500 metres height in the southern part of China. Its root has been used for the treatment of stomachache, dysentery, rheumatic arthritis, hypertension and virus hepatit…     

Two new glycosides from the genus of Cassia

Two new glycosides were isolated and characterized by spectral analysis from the seeds of Cassia obtusifolia and the leaves of Cassia angustifolia.The structure was elucidated as 1-hydroxyl-2-acetyl-3,8-dimethoxynaphthalene-6-O-β-D-apiofuranosyl- (1→2)-β-D-glucopyranoside and 2-acetyl-3-methyl-8-methoxyl-1,4-naphthoquinone-6-O-β-D-glucopyranoside.     

Resveratrol Tetramers from the Roots of Ampelopsis sinica

Various biological activities of stilbenoids have been described, such as antifungal and antibacterial activities1, antihepatotoxic activity2-4, anti-HIV activity5. Stilbenoids mainly existed in Vitaceae, Diperocarpaceae, Gnetaceae, Cyperaceae, Leguminase1. Many oligostilbenes have been isolated from Vitaceaeous plants. But, there was no report on the stilbenoids in Ampelopsis sinica (Miq.) W. T. Wang which was traditionari- ly used to treat arthritis6. In our study on the constituen…     

Monoterpene Glycosides from the Roots of Paeonia lactiflora

The roots of Paeonia lactiflora Pall. is one of the most important traditional Chinese medicines, which has been used for the treatment of dizziness, spasm, menstrual disorder, spontaneous and night sweating, and as a general analgesic1. Chemical constitu…     

New ceramides from the flower of Albizia iulibrissin

A new ceramide and its glycoside were isolated from the flower of Albizia julibrissin. Their structures were established as (25,35,4R,8E)-2-[(2'R)-hydroxyhexadecanoylamino]-8-tetra-cosene-l,3,4-triol(I)and 1-O-β-D-glucopyranosy1-(2S,3S,4R,8E)-2-[(2'R)-hydroxy-hexade-canoylamino]-8-tetracosene-1,3,4-triol (II) on the basis of chemical and spectroscopic studies.     

Structural Features of Fructans from the Root of Cyathula officinalis Kuan

Three fructans (CoPS1, CoPS2 and CoPS3) were isolated from the root of Cyathula officinalis Kuan, a traditional Chinese medicine. The structures of the fructans were determined by methylation, reductive-deavage method combined with GC-MS analysis, and 13C NMR spectroscopy. These results show that the fructans (CoPS1, CoPS2 and CoPS3) are graminan type fructans, and comprised of (2→t)- and (2→6)-linked β-D-fructofuranosyl backbone residues containing high branches.     

Application of the taraxerane–oleanane rearrangement to the synthesis of seco-oleanane triterpenoids from taraxerone

Synthetic oleananes and seco-oleananes form a group of promising anti-inflammatory and cancer chemopreventive agents with an excellent safety profile. These compounds are usually prepared by semi-synthesis from natural oleanane triterpenoids. Since a taraxer-14-ene was reported to be rearranged into an olean-12-ene under mild reaction conditions, a rapid synthesis of seco-oleananes from taraxerone, which is a readily available starting material, was explored by us. Treatment of taraxerone with m-chloroperoxybenzoic acid gave 14,15-epoxy lactones, which underwent the taraxerane–oleanane rearrangement leading to new seco-oleanane triterpenoids.     

Unraveling the Mechanism of the IrIII-Catalyzed Regiospecific Synthesis of α-Chlorocarbonyl Compounds from Allylic Alcohols

We have used experimental studies and DFT calculations to investigate the Ir^III-catalyzed isomerization of allylic alcohols into carbonyl compounds, and the regiospecific isomerization–chlorination of allylic alcohols into α-chlorinated carbonyl compounds. The mechanism involves a hydride elimination followed by a migratory insertion step that may take place at Cβ but also at Cα with a small energy-barrier difference of 1.8 kcal mol⁻¹. After a protonation step, calculations show that the final tautomerization can take place both at the Ir center and outside the catalytic cycle. For the isomerization–chlorination reaction, calculations show that the chlorination step takes place outside the cycle with an energy barrier much lower than that for the tautomerization to yield the saturated ketone. All the energies in the proposed mechanism are plausible, and the cycle accounts for the experimental observations.     

A Styrylpyrone Dimer from the Bark of Goniothalamus leiocarpus

A dimer of styrylpyrone derivative, leiocarpin E(1), was isolated from the bark of Goniothalamus leiocarpus. Its structures was elucidated by means of spectral and chemical methods. The cytotoxicity of leiocarpin E against HL-60 cells was tested.     

A New Sesquiterpene from the Roots of Lindera strychnifolia

The root of Lindera strychnifolia is used as a palliative and an antispasmodic in traditional chinese medicine. In previous studies of chemical constituents from this plant, more than 20 sesquiterpene lactones have been isolated and their structures were established1-7. In order to compare the difference of chemical constituents extracted by Supercritical Fluid Extraction (SFE) method and by organic solvent, the SFE extract from Lindera strychnifolia was investigated. A novel sesquiterp…     

A New Limonoid from the seed of Aphanamixis polystachya

A new limonoid named rohituka-15 1,with a known limonoid dregeana-1 2, was isolated from the seed of Aphanamixis polystachya (Meliaceae). The ^13C NMR data assignment of dregeana-1 2 and the structural clucidation of the new compound 1 were based on spectral analysis including ^1H-^1 COSY,HMQC and HMBC experments.