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 lac...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.展开更多
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 ...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.展开更多
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)...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.展开更多
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...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.展开更多
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 fr...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.展开更多
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...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.展开更多
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 m...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.展开更多
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...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.展开更多
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 ...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.展开更多
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 ...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.展开更多
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, I...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.展开更多
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,2...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.展开更多
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-rhamnopyra...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.展开更多
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 Ara...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.展开更多
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 mole...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.展开更多
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 spec...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.展开更多
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 or...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.展开更多
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 wh...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.展开更多
文摘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.
文摘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.
文摘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.
基金support from the Natural Sciences Foundation of China(82374035)the CAMS Innovation Fund for Medical Sciences(CIFMS,2022-I2M-1-017,China).
文摘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.
基金Financial support from the National Natural Science Foundations of China(No.22237007,22177121 and 92057116)supported by the grants from Science and Technology Commission of Shanghai Municipality(No.20ZR1467800 and 19431908100,China)。
文摘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.
文摘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.
文摘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.
文摘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.
基金Project supported by the State Science and Technology Commission of China.
文摘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.
文摘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.
文摘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.
基金This study was supported financially by the National Natural Science Foundation of China,China(No.31670364)Project of Key New Productions of Yunnan Province,China(No.2015BB002)+2 种基金the STS Programme of Chinese Academy of Sciences,China(KFJ-SW-STS-143-8)Special Fund Project of Pu’er municipal government,China(2017)Foundation of State Key Laboratory of Phytochemistry and Plant Resources in West China,China(P2015-ZZ09).
文摘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.
基金the National Natural Science Foundation of China(Grant Nos.31770388 and U1802281)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0502).
文摘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.
基金This work was supported financially by Programme of Key New Productions of Yunnan Province,Centre of CHINA(No.2015BB002)The STS Programme of Chinese Academy of Sciences(KFJ-SW-STS-143-8)as well as Foundation of State Key Laboratory of Phytochemistry and Plant Resources in West China(P2015-ZZ09).
文摘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.
基金The work was supported by grants from National High Technology Development Project(863 project)(No.2001AA620403 and 2002AA217081)NNSFC(30171106,40176038)
基金co-supported by National Natural Science Foundation of China(21572164,U1504207)the Sino-German Center for Research Promotion(GZ1289).
文摘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.
基金supported by the National Natural Science Foundation of China(No.29732040)
文摘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.
基金Supported by the National Nature Science Foundation of China(No.20202009).
文摘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.
文摘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.