STUDIES ON THE CHEMICAL CONSTITUENTS OF CLAUSENA LANSIUM(LOUR.)SKEELS Ⅲ.The structural elucidation of homo-and zeta-clausenamide(1)

The structures of two novel lactams isolated from Clausena lansium were elucidated mainly on the bases of their spectral data. They are homoclausenamide(1),a -lactam,and zetaclausenamide(4), an eight-membered ring lactam.

STUDIES ON THE CHEMICAL CONSTITUENTS OF CLAUSENA LANSIUM (LOUR.) SKEELS Ⅳ THE STRUCTURAL ELUCIDATION OF SECO-AND SECODEMETHYL-CLAUSENAMIDE

The spectral data and chemical properties of two new amides isolated from Clausena lansium led to the assignment of acyclic structures of C-6 and C-7. The absolute configurations of the two chiral carbons in C-6 were determined by degradation to be 3S4R.

Isolation and structural elucidation of the compounds from the fruits of Camptotheca acuminate

The fruit of Camptotheca acuminate is used as a traditional Chinese medicine.Eight compounds were isolated from the fruit of Camptotheca acuminate for the first time,including(+)-(S)-abscisic acid(1),blumenol A(2),(E)-3-hydroxymegastigm-7-en-9-one(3),(-)-(3R)-3,5-dimethyl-8-methoxy-3,4-dihydroisocoumarin(4),(-)-(3R)-8-methoxy-3-methyl-3,4-dihydro-1H-isochromen-1-one(5),neocnidilide(6),(3S)-butylphthalide(7)and senkyunolide I(8).Their structures were determined by comprehensive spectroscopic methods,including HRESIMS and 1D NMR.

A new class of potent liver injury protective compounds: Structural elucidation, total synthesis and bioactivity study

A new class of potent liver injury protective compounds,phychetins A-D(1-4)featuring an unique 6/6/5/6/5 pentacyclic framework,were isolated and structurally characterized from a Chinese medicinal plant Phyllanthus franchetianus.Compounds 2-4 are three pairs of enantiomers that were initially obtained in a racemic manner,and were further separated by chiral HPLC preparation.Compounds 1-4 were proposed to be originated biosynthetically from a coexisting lignan via an intramolecular Friedel-Crafts reaction as the key step.A bioinspired total synthesis strategy was thus designated,and allowed the effective syntheses of compounds 2-4 in high yields.Some of compounds exhibited significant anti-inflammatory activities in vitro via suppressing the production of pro-inflammatory cytokine IL-1β.Notably,compound 4,the most active enantiomeric pair in vitro,displayed prominent potent protecting activity against liver injury at a low dose of 3 mg/kg in mice,which could serve as a promising lead for the development of acute liver injury therapeutic agent.

Structural Elucidation and HPLC Analysis of Six Flavone Glycosides from Artemisiafrigida Willd.

An investigation of the EtOAc-soluble fraction from the aerial parts ofArtemisiafrigida Willd.（A. frigida） led to the isolation of three new flavonoid glycosides together with three known compounds. Their structures were elucidated by spectral experiments. At the same time, high-performance liquid chromatographic（HPLC） method was used for the simultaneous determination of the six flavonoid glycosides from the aerial parts ofA. frigida. The separation by gradient elution was performed on a Hypersil ODS-2 column（250 mm×4.6 mm, 5 μm） at 30℃ with acetonitrile and water as the mobile phase, and monitored by absorbance at 276 nm. The parameters of linearity, precision, accuracy and specificity of the method were evaluated. The recovery of the method is 96.50%--98.01%, and linearity（r〉0.9992） was obtained for all the flavonoid glycosides. A high degree of specificity as well as repeatability and reproducibility（relative standard deviation values less than 2.0%） were also achieved. This assay was applied to the determination of six flavonoid glycosides in ten samples. The results indicate that the developed assay method was rapid, accurate, reliable and could be readily utilized as a quantitative analysis method for A. frigida.

Contribution to Structural Elucidation: Behaviours of Substructures Partially Defined from 2D NMR

Structural elucidation (automatic determination of the structure of amolecule from its spectra) is frequently hampered by combinatorial explosion when trying to assemblethe identified substructures. We devised a new method which can avoid this pitfall by a systematicexamination of allowed ^(13)C chemical shifts ranges for all substructures chemically possible andcombined with a progressive pruning thanks to neighbouring relationships appearing from 2D NMR. Thismethod is explained by a detailed example.

Structural elucidation of sex pheromone components of the Geometridae Semiothisa cinerearia(Bremer et Grey)in China

An extract from the female sex gland of Semiothisa cinerearia attracted conspecific males in field tests.A major active component was isolated from the extract and identified by GC-MS,GC-IR and microchemical reactions as cis-3,4-cpoxy-(Z,Z)-6,9-heptadecadiene,which showed strong EAG response.Another minor yet important component was identified as (Z,Z,Z)-3,6,9-heptadecatriene.

Isolation and structural elucidation of a polysaccharide with radiation-protective activity from Spirulina platensis

The structure of a radiation-protective sulfated polysaccharide, SP-APS, isolated from Spirulina platensis, was investigated by methylation analysis, partial acetolysis and H-1-NMR spectroscopy. The repeating-unit of SP-APS as branched structures was elucidated.

ISOLATION AND STRUCTURE ELUCIDATION OF A NOVEL STEROL FROM THE SOUTH CHINA SEA SPONGE DYSIDEA SP.

A novel and unusual sterol with unsaturation in the△^(5(14)) position,5α-cholesta-8(14),24(25)-diene-3β,6α-diol 1,was isolated from the South China Ses sponge Dysidea sp.The structure and relative stereochemistry of 1 was established by spectral analysis and comparison to the spectral data of known sterols.

ISOLATION, STRUCTURE ELUCIDATION AND SYNTHESIS OF A NEW PRENYLATED FLAVONOL, MAACKIAFLAVONOL, FROM MAACKIA TENUIFOLIA

A new prenylated flavonol, maackiaflavonol, was isolated from the ethanol extract of the roots of Maackia tenuifolia. Its structure was elucidated as 7-hydrox-8-prenylflavonol by means of spectroscopic analysis (UV, IR, MS, NMR and 1H-1H COSY) and confirmed by total synthesis.

Isolation and Structure Elucidation of an Antifungal Antibiotics A73 Produced by a Soil Fungus Strain No.131

ＩｎｔｒｏｄｕｃｔｉｏｎＭｏｒｐｈｏｌｏｇｉｃａｌｄｅｆｏｒｍａｔｉｏｎｏｆｍｙｃｅｌｉａｏｒｃｏｎｉｄｉａｏｆｍｉｃｒｏｏｒｇａｎｉｓｍｓ，ｓｕｃｈａｓｃｕｒｌｉｎｇ，ｓｗｅｌｉｎｇ，ｈｙｐｅｒ－ｄｉｖｅｒｇｅｎｃｙ，ｂｅａｄｆｏｒｍａｔｉｏｎ，ａ...

Furostanol Saponins from Asparagus cochinchinensis and Their Cytotoxicity

Phytochemical investigation on the roots of Asparagus cochinchinensis led to the isolation of one new furostanol saponin,named 26-O-β-d-glucopyranosyl-22α-hydroxyl-(25R)-Δ5(6)-furost-3β,26-diol-3-O-α-l-rhamnopyranosyl-(1→2)-[β-d-glucopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→4)]-β-d-glucopyranoside(1),along with three known congeners(2‒4).The structure of new saponin was elucidated via comprehensive inspection of its HRMS and NMR spectral data as well as chemical technology,whereas those of known ones were identified by comparison of their NMR and MS spectral data with those reported in literatures.All isolated saponins were evaluated for their cytotoxic effects on two human liver(MHCC97H)and lung adenocarcinoma(H1299)cancer cells in vitro.Among them,both 1 and 2 showed significant cytotoxicity against above mentioned cell lines.Further studies revealed that these two saponins could significantly inhibit their proliferation of MHCC97H and H1299 cells.

Residual Dipolar Couplings in Structure Determination of Natural Products

The determination of natural products stereochemistry remains a formidable task.Residual dipolar couplings(RDCs)induced by anisotropic media are a powerful tool for determination of the stereochemistry of organic molecule in solution.This review will provide a short introduction on RDCs-based methodology for the structural elucidation of natural products.Special attention is given to the current availability of alignment media in organic solvents.The applications of RDCs for structural analysis of some examples of natural products were discussed and summarized.Graphical Abstract This review provides a short introduction on RDCs-based methodology for the structural elucidation of natural products.Special attention is given to the current availability of alignment media in organic solvents.The applications of RDCs for structural analysis of some examples of natural products were discussed and summarized.

Characterization of New Ent-kaurane Diterpenoids of Yunnan Arabica Coffee Beans

Five new ent-kaurane diterpenoids,named mascaroside Ⅲ–Ⅴ(1–3),and 20-nor-cofaryloside Ⅰ–Ⅱ(4–5),together with seven known diterpenoids,were isolated from methanol extracts of the green coffee beans of Yunnan Arabica Coffee.Their chemical structures were elucidated by extensive spectroscopic analyses.Meanwhile,cytotoxicity assay against HL-60,A-549,SMMC-7721,MCF-7 and SW480 cell lines showed that they have not evident inhibition of cytotoxicity.

New Dammarane Triterpenoids,Caffruones A–D,from the Cherries of Coffea arabica

In present study,four new dammarane-type triterpenoids,namely caffruones A–D(1–4),were isolated from the cherries of Coffea arabica.Their structures were elucidated by extensive spectroscopic analysis including 1D,2D NMR(HSQC,HMBC,^(1)H–^(1)H COSY,and ROESY),HRMS and IR spectra.This is the first time that tetracyclic triterpenes have been reported in genus Coffea.

A New Pseudo Sesquiterpenoid from the Seeds of Koelreuteria paniculata

From the seeds of medicinal plant Koelreuteria paniculata, a new pseudo sesquiter- penoid with novel skeleton namely paniculoid 1 was isolated. The structure of 1 was established on the basis of extensive 2D NMR spectroscopy in conjugation with MS and IR spectral analysis.

Synthesis and Characterization of a Novel Podophyllotoxin Derivative Containing a Cyclohexadienone Group

4β-Azido-4-demethyl-4＇-O-demethyl-epipedophyllotoxin reacted with phenyliodonium diacetate in MeOH at room temperature to synthesize a novel pedophyllotoxin derivative containing a cyclohexadienone group with the original configurations of C2 and C4, which are required for the antitumor activities. The component and structure of the pro-duct were confirmed using elemental analysis, high-resolution mass spectrum, ^1H and ^13C NMR spectra, and infrared spectrum. Furthermore, the fragmentation routes of the product were fully assigned with electron-impaet time-of-flight mass spectrometry（ EI-TOF MS）, which can also be used for the structural elucidation based on the molecular ion at m/z 455（16% ） and three novel characteristic fragment ions at m/z 183（37% ）, 425（7% ）, and 199（5% ）. The cyclohexadienone product is sensitive to acidic media. When it is treated with a trace of acid, another novel derivative containing an orthoquinone moiety is formed, which links with the metabolism of the cancer inhihitors.

Isolation and identification of chemical constituents from Elephantopus scaber Linn.

Elephantopus scaber L.,as a popular Chinese medicinal herb of the Compositae family,is widely distributed in America,Africa and Asia.In the present study,five compounds were isolated from the 70%EtOH extract of the whole herb from Elephantopus scaber L.,including two lignans and three flavones.Their chemical structures were identified based on NMR spectroscopic analysis and comparison with the data reported in literature.It is noteworthy that compounds 1-5 were isolated from Elephantopus scaber L.for the first time and their chemotaxonomic significance was discussed.

A new dimeric furanocoumarin from Notopterygium incisum

A new dimeric psoralen-type furanocoumarin, notopterol-（18-O-20＇）-notopol （1）, was isolated from Notopterygium incisum for the first time and its structure was elucidated by spectroscopic methods.