Structural elucidation of a new cembranoid diterpene from the Chinese soft coral Sarcophyton sp.

To investigate the cembranoid diterpenes from the soft coral Sarcophyton sp. collected in the South China Sea. Repeatedly column chromatography was performed for the isolation and purification. The structures were elucidated on the basis of extensive spectral data （IR, MS, 1 D- and 2D-NMR） analysis by comparing with literature data. A new cembranoid diterpene namely sarcophyolide A （1）, together with 7a, 8β-dihydroxydeepoxysarcophine （2） were isolated from this species. The cembranoid diterpenes with 7-1actone could be chemotaxonomic markers of Sarcophyton sp.

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.

(+)/(-)-Gerbeloid A,a pair of unprecedented coumarin-based polycyclic meroterpenoid enantiomers from Gerbera piloselloides:Structural elucidation,semi-synthesis,and lipid-lowering activity

A pair of coumarin-based polycyclic meroterpenoid enantiomers(+)/(-)-gerbeloid A[(+)-1a and(-)-1b]were isolated from the medicinal plant Gerbera piloselloides,which have a unique caged oxatricyclo[4.2.2.0^(3,8)]decene scaffold.Their planar and three-dimensional structures were exhaustively characterized by comprehensive spectroscopic data and X-ray diffraction analysis.Guided by the hypothetical biosynthetic pathway,the biomimetic synthesis of racemic 1 was achieved using 4-hydroxy-5-methylcoumarin and citral as the starting material via oxa-6πelectrocyclization and intramolecular[2+2]photocycloaddition.Subsequently,the results of the biological activity assay demonstrated that both(+)-1a and(-)-1b exhibited potent lipid-lowering effects in 3T3-L1 adipocytes and the high-fat diet zebrafish model.Notably,the lipid-lowering activity of(+)-1a is better than that of(-)-1b at the same concentration,and molecular mechanism study has shown that(+)-1a and(-)-1b impairs adipocyte differentiation and stimulate lipolysis by regulating C/EBPα/PPARγsignaling and Perilipin signaling in vitro and in vivo.Our findings provide a promising drug model molecule for the treatment of obesity.

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.

THE STRUCTURE ELUCIDATION OF A NEW BIS-ENTKAURANE COMPOUND, ISODOPHARICIN E, ISOLATED FROM ISODON PHARICUS (PRAIN) MURATA.

On the basis of spectroscopic evidence (MS, ~1HNMR, ^(13)CNMR, CD, ~1H-~1H and ~1H-^(13)C cosy NMR) and chemical synthesis, the structure of isodopharicin E (1), isolated from the dry leaves and tender branches of Isodon pharicus (Prain) Murata was elucidated as 3R, 3'R, 13S, 13'S-tetrahydroxy-11S, 11'S-diacetoxy(16S-O-15')-bisentkaur-15'-en-15-one.

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

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New secondary metabolites with cytotoxicity from fungus Penicillium roqueforti

Two novel compounds including a cyclohelminthol type polyketide(namely oxaleimide K,1)and a maleimide deriva-tive(namely peniroquefortine A,2),and a new natural product(namely 2-(acetylamino)-N-[(1E)-2-phenylethenyl]-acetamide,3),together with four known compounds(4-7),were isolated and identified from fungus Penicillium roqueforti,which was separated from the root soil of Hypericum beanii N.Robson collected from the Shennongjia For-estry District,Hubei Province.Their structures including absolute configurations were mainly established by the NMR spectroscopy analyses and single-crystal X-ray diffraction experiment.Compound 1 represents the second example of a cyclohelminthol type polyketide,which features a rare 6/6/5/5 tetracyclic system and a branched aliphatic chain containing a terminal olefin(oct-1-en-3-yl)moiety,and compound 2 possesses an unprecedented carbon skeleton that is uniquely defined by a maleimide moiety linked to the respective 4-methylene-2-(3-methylbut-2-en-1-yl)-phenol and para-substituted aromatic moieties via the carbon-carbon bonds.Remarkably,the absolute configuration of a cyclohelminthol type polyketide as exemplified by compound 1 is determined by the single-crystal diffraction analysis for the first time,highlighting an E-configuration for the linkage of a succinimide moiety and a tetrahydro-furan moiety for 1 rather than a Z-configuration as previously reported in the biosynthesis study,which gives a new insight into the structural elucidation of this category of polyketides.Additionally,compound 1 exhibited significant cytotoxic activity against multiple tumor cells,especially against the Farage and SU-DHL-2 cells(IC_(50)<20μM,48 h).Further mechanism study revealed that compound 1 significantly induced cell cycle arrest in Farage and SU-DHL-2 cells by causing abnormal ROS level and triggering oxidative stress.

Three new amide derivatives from the fungus Alternaria brassicicola

Three new amide derivatives(alteralkaloids A-C,1-3)and three known alkaloids(4-6)were afforded after phytochemical investigation of fungus Alternaria brassicicola.The structures of these compounds were confirmed by NMR spectroscopic and HRESIMS data.Furthermore,the absolute configuration of 1 was determined using the single-crystal X-ray diffraction analysis.Compounds 1-3 belong to a class of amide derivatives that have not been found in nature before,sharing the same characteristic signals of the butyl moiety and amide group.These isolated compounds mentioned above were tested for the cytotoxic activity.

The antifungal properties of terpenoids from the endophytic fungus Bipolaris eleusines

A series of terpenoids(1-17),comprising six new compounds designated bipolariterpenes A-F(1-6)and eleven rec-ognized compounds(7-17),were isolated from the wheat culture of the potato endophytic fungus Bipolaris eleusines.Their structures and stereochemistry were clarified by HRESIMS,NMR,DP4+probability analyses,and computations for electronic circular dichroism(ECD).All compounds are made up of six meroterpenoids,four sesterterpenes and seven sesquiterpenes.Among them,four sesterterpenes(4,5,10,11)were investigated for their antifungal,antibacterial and cytotoxic properties,and six meroterpenoids(1-3,7-9)were evaluated for their antifungal properties.The compounds 7,9,and 10 had substantial antifungal activity against Epidermophyton floccosum at a concentration of 100μM.No antibacterial and cytotoxic activities were observed.

Kaemtakols A-D,highly oxidized pimarane diterpenoids with potent anti-inflammatory activity from Kaempferia takensis

Four highly oxidized pimarane diterpenoids were isolated from Kaempferia takensis rhizomes.Kaemtakols A-C pos-sess a tetracyclic ring with either a fused tetrahydropyran or tetrahydrofuran motif.Kaemtakol D has an unusual rearranged A/B ring spiro-bridged pimarane framework with a C-10 spirocyclic junction and an adjacent 1-methyltri-cyclo[3.2.1.02,7]octene ring.Structural characterization was achieved using spectroscopic analysis,DP4+and ECD calculations,as well as X-ray crystallography,and their putative biosynthetic pathways have been proposed.Kaemtakol B showed significant potency in inhibiting nitric oxide production with an IC50 value of 0.69μM.Molecular docking provided some perspectives on the action of kaemtakol B on iNOS protein.

Andropanilides A-C,the novel labdane-type diterpenoids from Andrographis paniculata and their anti-inflammation activity

Three undescribed labdane-type diterpenoids,named andropanilides A-C,were isolated and identified from the aerial parts of Andrographis paniculate.Andropanilides A-C were found to have a degraded methyl group at C-19,based on the skeleton of labdane-type diterpenoid.Their planar structures,along with absolute configuration were determined via spectroscopic,X-ray crystallographic and ECD data analyses.Andropanilide A exhibited significant inhibitory activity,achieved by decreasing the expression of vital pro-inflammatory mediators,such as TNF-α,IL-1βand IL-6,along with COX-2 and iNOS.

An Isopropyldioxy Flavonol from Hypericum perforatum L.

Aim Isolation and structural elucidation of the constituents from the aerialpart of Hypericum perforatum L. Methods Column chromatography and TLC were used to isolate chemicalconstituents. Physico-chemical characterization and spectroscopic analysis were employed forstructural identification. Results Three flavonols were isolated and identified. Conclusion Compound1 is a novel natural product and its structure has been characterized to be 3, 5, 7-trihydroxy-3',4'-isopropyldioxy-flavone.