Owing to their intricate molecular frameworks and copious chiral centers,the structural identification and configurational assignment of natural products are challenging tasks.Comprehensive spectral data analysis is c...Owing to their intricate molecular frameworks and copious chiral centers,the structural identification and configurational assignment of natural products are challenging tasks.Comprehensive spectral data analysis is crucial for the confirmation of absolute configurations.Ignoring critical parameters will lead to false structure,which may confuse the total synthesis and drug development.Herein,the configurations of seven heterogeneous Pallavicinia diterpenoids(PDs) isolated from Pallavicinia liverworts are revised using a combination of single-crystal X-ray diffraction and electronic circular dichroism(ECD) calculations.Meanwhile,identification of five unprecedented PD heterodimers PD-dimers A-E(18-22) along with eleven previously undescribed PDs(5-9,13-17,23) obtained by the reinvestigation of the Chinese liverwort Pallavicinia subciliata have resulted in corrections and support the revised conclusions.展开更多
Podophyllotoxone(1) was isolated from the roots of Dysosma versipellis. The structure was determined by spectroscopic analysis in combination with single-crystal X-ray analysis. The absolute configuration of compound ...Podophyllotoxone(1) was isolated from the roots of Dysosma versipellis. The structure was determined by spectroscopic analysis in combination with single-crystal X-ray analysis. The absolute configuration of compound 1 was assigned based on the Flack parameter. It showed significant inhibitory activities against human prostate cancer cells PC3 and DU145 with IC50 values being 14.7 and 20.6 μmol·L-1, respectively. It also arrested the cells at G2/M phase. Tubulin polymerization assay showed that it inhibited the tubulin polymerization in a dose-dependent manner, and molecular docking analysis revealed a different binding mode with tubulin as compared with those known tubulin inhibitors.展开更多
Correlation between the absolute configuration and the CD spectra of organic peroxides was studied by ab initio method with a mo- d el moleeule CH_3-O-O-CH_3.For P form when 0°≤θ(twist angle of C-O-O-C) <90&...Correlation between the absolute configuration and the CD spectra of organic peroxides was studied by ab initio method with a mo- d el moleeule CH_3-O-O-CH_3.For P form when 0°≤θ(twist angle of C-O-O-C) <90°, there is positive Cotton effect;when 90°<θ≤180°, there is nega- tive Cotton effect;the curve is bisignate at θ=90°.展开更多
Buagafuran is a novel drug candidate derived from natural product.Its absolute configuration has been confirmed by electronic circular dichroism combined with modern quantum-chemical calculation using time-dependent d...Buagafuran is a novel drug candidate derived from natural product.Its absolute configuration has been confirmed by electronic circular dichroism combined with modern quantum-chemical calculation using time-dependent density functional theory.The predicted UV absorbance peak is underestimated by several nanometers compared with the experimental data.The applicability of empirical rule for the C=C-C-O system in Buagafuran has also been discussed.Our results show that electronic circular dichroism could be a useful tool for the absolute configuration assignment of chiral drugs,especially for the oily or semisolid substances,whose crystal structures are impossible to obtain.展开更多
To investigate the anti-ulcer effect of bisabolangelone reduction derivatives, the sesquiterpene was further proceeded with dihydroxylation reaction. The structure of the target compound was characterized by IR, ESI-M...To investigate the anti-ulcer effect of bisabolangelone reduction derivatives, the sesquiterpene was further proceeded with dihydroxylation reaction. The structure of the target compound was characterized by IR, ESI-MS, 2D NMR and elemental analysis, and its absolute configuration was confirmed with a Flack parameter of 0.08（16） by X-ray crystallography using a Cu radiation source. Compound（3）, C（15）H（26）O5, crystal data： monoclinic system, space group P21, a = 11.467（2）, b = 6.0303（12）, c = 11.711（2） A, β = 99.70（3）°, V = 798.3（3） A3, Z = 2, F（000） = 312, Dc = 1.191 g/cm3, μ = 0.723 mm-1） R = 0.0303 and wR = 0.0797 for 2590 independent reflections（Rint = 0.0164） and 2563 observed ones（I 〉 2σ（I））.展开更多
The absolute configuration of rohitukine, isolated from the stem-bark of Dysoxylum binectariferum, was determined to be 5,7-dihydroxy-2-methyl-8-[4-(3S, 4R-3-hydroxy-1-methyl) -piperidinyl]-4H-1-benzopyran-4-one by X-...The absolute configuration of rohitukine, isolated from the stem-bark of Dysoxylum binectariferum, was determined to be 5,7-dihydroxy-2-methyl-8-[4-(3S, 4R-3-hydroxy-1-methyl) -piperidinyl]-4H-1-benzopyran-4-one by X-ray crystallographic analysis on the crystal of 4-bromobenzoyl derivatives of rohitukine. At the same time, the modified Mosher method was proved to be unsuitable for determining the absolute configuration of C-3 position in rohitukine.展开更多
A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(...A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(residual dipolar coupling)-based NMR and DFT-supported chiroptical spectroscopy.It is worth to note that in this study without the aid of the RDC analysis,an unambiguous determination of configuration and conformation was not feasible due to the excessive conformational possibilities of this open-chain compound.展开更多
Racemic O-methyl O-pheayl thiophosphoric acid 1 has been successfully resolved through its quinine and brucine salts in methanol solution by fractional crystallization. The absolute configurations of the optically act...Racemic O-methyl O-pheayl thiophosphoric acid 1 has been successfully resolved through its quinine and brucine salts in methanol solution by fractional crystallization. The absolute configurations of the optically active 1 have been established as (+)-R-1 and (-)-S-1 by chemical correlation.展开更多
The title compound (+)-(a-hydroxybenzyl)phenylphosphinic acid (C13H13O3P, Mr = 248.20) has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 293(2) K indicates...The title compound (+)-(a-hydroxybenzyl)phenylphosphinic acid (C13H13O3P, Mr = 248.20) has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 293(2) K indicates that the compound belongs to monoclinic system, space group C2 with cell parameters: a = 23.560(8), b = 6.947(2), c = 7.854(3) ? b = 91.273(6)? V = 1285.2(7) 3, Z = 4, Dc = 1.283 g/cm3, F(000) = 520 and m(MoKa) = 0.207 mm-1. The number of independent reflections amounts to 1991, of which 1507 are observed reflections. The crystal structure has been determined by direct methods (SHELXL-97). The structure parameters are refined by full-matrix least-squares on F2 to R = 0.0437 and wR = 0.0893. The flack x parameter is 0.0001. The absolute configuration of the a-carbon in the title compound is S.展开更多
The title compound, (+)-O-phenyl cyclophosphorodiamidate (C28H33N2O2P, Mr = 460.53), has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 273(2) K indicates t...The title compound, (+)-O-phenyl cyclophosphorodiamidate (C28H33N2O2P, Mr = 460.53), has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 273(2) K indicates that it belongs to orthorhombic system, space group P212121 with a = 11.518(4), b = 13.449(4), c = 16.539(5) ? V = 2562(1) 3, Z = 4, Dc = 1.194 g/cm3, F(000) = 984 and m(MoKa) = 0.134 mm-1. The structure parameters were refined by full-matrix least-squares on F2 to R = 0.0459 and wR = 0.0640. The flack x parameter is 0.03(10), and the absolute configuration of the phosphorus atom in the title compound is S.展开更多
Crystal structure of the levocloperastine fendizoate （C80H76Cl2N2O10, C20H25ClNO＋· C20H13O4-） has been determined by single-crystal X-ray diffraction. The crystal is of triclinic system, space group P1 with a ...Crystal structure of the levocloperastine fendizoate （C80H76Cl2N2O10, C20H25ClNO＋· C20H13O4-） has been determined by single-crystal X-ray diffraction. The crystal is of triclinic system, space group P1 with a = 10.1059（18）, b = 11.957（2）, c = 15.383（3） , α = 104.666（2）, β = 90.9700（10）, γ = 110.744（2）°, Z = 1, V = 1670.0（5） 3, Dc = 1.289 g/cm3, F（000） = 684, μ（MoKα） = 0.161 mm-1, Mr = 1296.33, the final R = 0.0343 and wR = 0.0676. The cations and anions are linked by the COO…NH hydrogen bonds of 2.709（3） and 2.690（3） and COO…OH hydrogen bonds of 2.632（3） and 2.631（3） . The configuration of the only one chiral carbon atom in this compound is R（rectus）.展开更多
Three pairs of glycosidic 8,4′-oxyneolignane diastereoisomers, named isatioxyneolignosides A-F(1–6), were isolated from an aqueous extract of Isatis indigotica roots. Their structures and absolute configurations wer...Three pairs of glycosidic 8,4′-oxyneolignane diastereoisomers, named isatioxyneolignosides A-F(1–6), were isolated from an aqueous extract of Isatis indigotica roots. Their structures and absolute configurations were elucidated by comprehensive spectroscopic data analysis and enzyme hydrolysis. The validity of Δδ_(C8-C7) values to distinguish threo and erythro aryl glycerol units and Cotton effects at 235±5 nm to determine absolute configurations at C-8 in 1–6 and their aglycones(1a–6a) are discussed.展开更多
A stereo-selective palladium-catalyzed one-pot Tsuji-Trost reaction was used to prepare fourβ-thiogalactosides from unsaturated D-galactal and thiol.Their structures were characterized by nuclear magnetic resonance s...A stereo-selective palladium-catalyzed one-pot Tsuji-Trost reaction was used to prepare fourβ-thiogalactosides from unsaturated D-galactal and thiol.Their structures were characterized by nuclear magnetic resonance spectra and high-resolution electrospray ionization mass spectra.The absolute configuration was confirmed with a Flack parameter of 0.019(15)by X-ray crystallography using a Cu radiation source.Compound 6 a(C_(21)H_(24)O_(4)S):orthorhombic system,space group P2_(1)2_(1)2_(1),a=9.0919(4),b=9.6313(4),c=22.5936(11)A,V=1978.45(15)A^(3),Z=4,F(000)=792,D_(c)=1.250 g/cm^(3),μ=1.636 mm^(-1),R=0.0478 and wR=0.1384 for 3621 independent reflections(Rint=0.0390)and 3326 observed ones(I>2σ(I)).3-(4,5)-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide(MTT)cell viability assays indicated that these thiogalactosides showed anti-proliferative activities against human gastric cancer HGC-27 cells with IC_(50)values of 69~88μM.展开更多
Lewis acid-catalyzed[1,3]-sigmatropic O→C rearrangement was used to synthesize C-glycosides derivatives.The structure of the target compound was characterized by NMR and HR-ESI-MS,and its absolute configuration was c...Lewis acid-catalyzed[1,3]-sigmatropic O→C rearrangement was used to synthesize C-glycosides derivatives.The structure of the target compound was characterized by NMR and HR-ESI-MS,and its absolute configuration was confirmed.Compound 8(C(29)H(29)ClN4O7):monoclinic system,space group P212121,a=6.1484(2),b=12.3625(3),c=37.0127(8)A,V=2813.32(13)A3,Z=4,F(000)=1216.0,Dc=1.372 g/cm^3,μ=1.662 mm^1,R=0.0522 and wR=0.1358 for 5611 independent reflections(R(int)=0.0778)and 5169 observed ones(I>2σ(I)).展开更多
Monosaccharides are one of the most important structural components of biomolecules, such as polysac- charides, nucleic acids, glycolipids and glycoproteins. In structural analysis of polysaccharides and gly- coconjug...Monosaccharides are one of the most important structural components of biomolecules, such as polysac- charides, nucleic acids, glycolipids and glycoproteins. In structural analysis of polysaccharides and gly- coconjugates, the absolute configurations （D or L） of the constituent monosaccharides are usually deter- mined by measurement of the optical rotation, CD spectra or characteristic chromatographic retention behavior. However, each method has its unique advantages and limitations which should be considered while using them. In this review, an overview of the different methods for the determination of absolute configuration of monosaccharides and their underlying principles are summarized to serve as a reference for researchers.展开更多
Since two asymmetric centres are usually present in the bisbenzylisoquinolines,the circular dichroism is known to be an important method to elucidate their stereochemistry.We studied the relationships of the CD spectr...Since two asymmetric centres are usually present in the bisbenzylisoquinolines,the circular dichroism is known to be an important method to elucidate their stereochemistry.We studied the relationships of the CD spectra with the stereochemistry of synthetic RR-(1),SS-(2),RS-daurisoline(3) and SR-daurisoline(4).By comparision of the CD spectrum of natural daurisoline(1)from Menis- permum dauricum(Menispermaceae)with those of synthetic enantiomers,the absolute configuration was established as RR-daurisoline(1).展开更多
Ten previously undescribed rearranged 4,9-friedodrimane merosesquiterpenoids,designated ircinrimanes A-J(1-10),were isolated from the marine sponge Ircinia sp.,collected from the South China Sea.Their structures and a...Ten previously undescribed rearranged 4,9-friedodrimane merosesquiterpenoids,designated ircinrimanes A-J(1-10),were isolated from the marine sponge Ircinia sp.,collected from the South China Sea.Their structures and absolute configurations were definitively elucidated through a combination of spectroscopic data analysis,DP4+probability assessments,electronic circular dichroism(ECD)calculations,and Mo2(OAc)4 experiment.Compounds 1-4contained benzene rings,with compound 1 featuring an unusual 2-carbonyl morpholin ring,while compound 2 possessed a benzoxazole ring.Compounds 5-9 comprised sesquiterpenoid quinones with distinct amino side chains at C-20,and compound 10 incorporated an ethoxy side chain.Notably,compounds 1-10 demonstrated an unusual rearrangement of 4,9-friedodrimane sesquiterpenes.Compounds 2,5-8 and 10 demonstrated cytotoxic activity,while compound 2 exhibited anti-inflammatory activity in zebrafish.展开更多
Two new ent-rosane type diterpenoids, anomalusins A （1） and B （2）, together with ten known compounds were isolated from the plants of Mallotus anomalus Meer et Chun. The structures of compounds 1 and 2 were fully ...Two new ent-rosane type diterpenoids, anomalusins A （1） and B （2）, together with ten known compounds were isolated from the plants of Mallotus anomalus Meer et Chun. The structures of compounds 1 and 2 were fully elucidated on the basis of spectroscopic evidence, and CD analysis.展开更多
Two cyclopeptides, celogentin L(1) and its epimer lyciumin A(2) were firstly isolated from Celosia argentea L.. The planar structures of the two compounds were fully determined by spectroscopic data, including 1 D-, 2...Two cyclopeptides, celogentin L(1) and its epimer lyciumin A(2) were firstly isolated from Celosia argentea L.. The planar structures of the two compounds were fully determined by spectroscopic data, including 1 D-, 2 D-NMR, and HR-ESI/MS. The absolute configurations of amino acid components were assigned via chiral-phase HPLC analyses after acid hydrolysis. Furthermore, the configuration of C-N linkage at the glycine Cα was elucidated by extensive analyses of 2 D-NMR and comparison of the experimental and calculated electronic circular dichroism(ECD) spectra. Cytotoxicity of the two compounds against human alveolar epithelial A549, hepatocellular carcinoma Hep G2, and cervical cancer Hela cell lines was assayed. Although both of them were inactive in these cells, the present findings add new facets for the chemistry of Celosia argentea.展开更多
基金supported by the National Natural Science Foundation of China (Nos.82293682,82293684,and 82173703)。
文摘Owing to their intricate molecular frameworks and copious chiral centers,the structural identification and configurational assignment of natural products are challenging tasks.Comprehensive spectral data analysis is crucial for the confirmation of absolute configurations.Ignoring critical parameters will lead to false structure,which may confuse the total synthesis and drug development.Herein,the configurations of seven heterogeneous Pallavicinia diterpenoids(PDs) isolated from Pallavicinia liverworts are revised using a combination of single-crystal X-ray diffraction and electronic circular dichroism(ECD) calculations.Meanwhile,identification of five unprecedented PD heterodimers PD-dimers A-E(18-22) along with eleven previously undescribed PDs(5-9,13-17,23) obtained by the reinvestigation of the Chinese liverwort Pallavicinia subciliata have resulted in corrections and support the revised conclusions.
基金supported by the Fund of Guangxi Key Laboratory of Functional Phytochemicals Research and Utilization(Nos.FPRU2013-4,and ZRJJ2013-4)the National Natural Science Foundation of China(No.21072078)+1 种基金the Fundamental Research Funds for the Central Universities(No.11609202)the Guangdong High Level Talent Scheme to R.W.J
文摘Podophyllotoxone(1) was isolated from the roots of Dysosma versipellis. The structure was determined by spectroscopic analysis in combination with single-crystal X-ray analysis. The absolute configuration of compound 1 was assigned based on the Flack parameter. It showed significant inhibitory activities against human prostate cancer cells PC3 and DU145 with IC50 values being 14.7 and 20.6 μmol·L-1, respectively. It also arrested the cells at G2/M phase. Tubulin polymerization assay showed that it inhibited the tubulin polymerization in a dose-dependent manner, and molecular docking analysis revealed a different binding mode with tubulin as compared with those known tubulin inhibitors.
文摘Correlation between the absolute configuration and the CD spectra of organic peroxides was studied by ab initio method with a mo- d el moleeule CH_3-O-O-CH_3.For P form when 0°≤θ(twist angle of C-O-O-C) <90°, there is positive Cotton effect;when 90°<θ≤180°, there is nega- tive Cotton effect;the curve is bisignate at θ=90°.
基金supported by the Fundamental Research Funds for the Central Institutes(No.2012ZD03)
文摘Buagafuran is a novel drug candidate derived from natural product.Its absolute configuration has been confirmed by electronic circular dichroism combined with modern quantum-chemical calculation using time-dependent density functional theory.The predicted UV absorbance peak is underestimated by several nanometers compared with the experimental data.The applicability of empirical rule for the C=C-C-O system in Buagafuran has also been discussed.Our results show that electronic circular dichroism could be a useful tool for the absolute configuration assignment of chiral drugs,especially for the oily or semisolid substances,whose crystal structures are impossible to obtain.
基金supported by the National Natural Science Foundation of China(No.21602123)China Scholarship Council(No.201508420062)Youth Talent Development Foundation of China Three Gorges University
文摘To investigate the anti-ulcer effect of bisabolangelone reduction derivatives, the sesquiterpene was further proceeded with dihydroxylation reaction. The structure of the target compound was characterized by IR, ESI-MS, 2D NMR and elemental analysis, and its absolute configuration was confirmed with a Flack parameter of 0.08（16） by X-ray crystallography using a Cu radiation source. Compound（3）, C（15）H（26）O5, crystal data： monoclinic system, space group P21, a = 11.467（2）, b = 6.0303（12）, c = 11.711（2） A, β = 99.70（3）°, V = 798.3（3） A3, Z = 2, F（000） = 312, Dc = 1.191 g/cm3, μ = 0.723 mm-1） R = 0.0303 and wR = 0.0797 for 2590 independent reflections（Rint = 0.0164） and 2563 observed ones（I 〉 2σ（I））.
文摘The absolute configuration of rohitukine, isolated from the stem-bark of Dysoxylum binectariferum, was determined to be 5,7-dihydroxy-2-methyl-8-[4-(3S, 4R-3-hydroxy-1-methyl) -piperidinyl]-4H-1-benzopyran-4-one by X-ray crystallographic analysis on the crystal of 4-bromobenzoyl derivatives of rohitukine. At the same time, the modified Mosher method was proved to be unsuitable for determining the absolute configuration of C-3 position in rohitukine.
基金Support by the National Natural Science Foundation of China(U1132607)to J.K.L.the DFG(Forschergruppe FOR 934)to C.Gas well as the Chinese/German foundation(GZ1104)to H.S.and C.G.is acknowledged.
文摘A new alkylpyrrole derivative,fusariumin A(1),was isolated from the culture broth of the fungus Fusarium sp.The absolute configuration of fuasiumin A has been established as(2'R,3'R)using a combination of RDC(residual dipolar coupling)-based NMR and DFT-supported chiroptical spectroscopy.It is worth to note that in this study without the aid of the RDC analysis,an unambiguous determination of configuration and conformation was not feasible due to the excessive conformational possibilities of this open-chain compound.
基金This project was supported by National Natural Science Foundation of China
文摘Racemic O-methyl O-pheayl thiophosphoric acid 1 has been successfully resolved through its quinine and brucine salts in methanol solution by fractional crystallization. The absolute configurations of the optically active 1 have been established as (+)-R-1 and (-)-S-1 by chemical correlation.
基金Financial support by the National Natural Science Foundation of China (No.29872016)
文摘The title compound (+)-(a-hydroxybenzyl)phenylphosphinic acid (C13H13O3P, Mr = 248.20) has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 293(2) K indicates that the compound belongs to monoclinic system, space group C2 with cell parameters: a = 23.560(8), b = 6.947(2), c = 7.854(3) ? b = 91.273(6)? V = 1285.2(7) 3, Z = 4, Dc = 1.283 g/cm3, F(000) = 520 and m(MoKa) = 0.207 mm-1. The number of independent reflections amounts to 1991, of which 1507 are observed reflections. The crystal structure has been determined by direct methods (SHELXL-97). The structure parameters are refined by full-matrix least-squares on F2 to R = 0.0437 and wR = 0.0893. The flack x parameter is 0.0001. The absolute configuration of the a-carbon in the title compound is S.
基金Financially supported by the National Natural Science Foundation of China (No.20272025) and Ph.D. Programs Foundation of Ministry of Education of China
文摘The title compound, (+)-O-phenyl cyclophosphorodiamidate (C28H33N2O2P, Mr = 460.53), has been synthesized and characterized by 31P NMR, 1H NMR and elemental analysis. X-ray diffraction analysis at 273(2) K indicates that it belongs to orthorhombic system, space group P212121 with a = 11.518(4), b = 13.449(4), c = 16.539(5) ? V = 2562(1) 3, Z = 4, Dc = 1.194 g/cm3, F(000) = 984 and m(MoKa) = 0.134 mm-1. The structure parameters were refined by full-matrix least-squares on F2 to R = 0.0459 and wR = 0.0640. The flack x parameter is 0.03(10), and the absolute configuration of the phosphorus atom in the title compound is S.
文摘Crystal structure of the levocloperastine fendizoate （C80H76Cl2N2O10, C20H25ClNO＋· C20H13O4-） has been determined by single-crystal X-ray diffraction. The crystal is of triclinic system, space group P1 with a = 10.1059（18）, b = 11.957（2）, c = 15.383（3） , α = 104.666（2）, β = 90.9700（10）, γ = 110.744（2）°, Z = 1, V = 1670.0（5） 3, Dc = 1.289 g/cm3, F（000） = 684, μ（MoKα） = 0.161 mm-1, Mr = 1296.33, the final R = 0.0343 and wR = 0.0676. The cations and anions are linked by the COO…NH hydrogen bonds of 2.709（3） and 2.690（3） and COO…OH hydrogen bonds of 2.632（3） and 2.631（3） . The configuration of the only one chiral carbon atom in this compound is R（rectus）.
基金Financial support from the National Natural Sciences Foundation of China(NNSFCGrant Nos.81373287,81630094,and 30825044)
文摘Three pairs of glycosidic 8,4′-oxyneolignane diastereoisomers, named isatioxyneolignosides A-F(1–6), were isolated from an aqueous extract of Isatis indigotica roots. Their structures and absolute configurations were elucidated by comprehensive spectroscopic data analysis and enzyme hydrolysis. The validity of Δδ_(C8-C7) values to distinguish threo and erythro aryl glycerol units and Cotton effects at 235±5 nm to determine absolute configurations at C-8 in 1–6 and their aglycones(1a–6a) are discussed.
基金the National Natural Science Foundation of China(No.82003621)Natural Science Foundation of Hubei Province(2020CFB205)Educational Commission of Hubei Province(Q20201204)。
文摘A stereo-selective palladium-catalyzed one-pot Tsuji-Trost reaction was used to prepare fourβ-thiogalactosides from unsaturated D-galactal and thiol.Their structures were characterized by nuclear magnetic resonance spectra and high-resolution electrospray ionization mass spectra.The absolute configuration was confirmed with a Flack parameter of 0.019(15)by X-ray crystallography using a Cu radiation source.Compound 6 a(C_(21)H_(24)O_(4)S):orthorhombic system,space group P2_(1)2_(1)2_(1),a=9.0919(4),b=9.6313(4),c=22.5936(11)A,V=1978.45(15)A^(3),Z=4,F(000)=792,D_(c)=1.250 g/cm^(3),μ=1.636 mm^(-1),R=0.0478 and wR=0.1384 for 3621 independent reflections(Rint=0.0390)and 3326 observed ones(I>2σ(I)).3-(4,5)-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide(MTT)cell viability assays indicated that these thiogalactosides showed anti-proliferative activities against human gastric cancer HGC-27 cells with IC_(50)values of 69~88μM.
基金the National Natural Science Foundation of China(No.21602123)Youth Talent Development Foundation of China Three Gorges University。
文摘Lewis acid-catalyzed[1,3]-sigmatropic O→C rearrangement was used to synthesize C-glycosides derivatives.The structure of the target compound was characterized by NMR and HR-ESI-MS,and its absolute configuration was confirmed.Compound 8(C(29)H(29)ClN4O7):monoclinic system,space group P212121,a=6.1484(2),b=12.3625(3),c=37.0127(8)A,V=2813.32(13)A3,Z=4,F(000)=1216.0,Dc=1.372 g/cm^3,μ=1.662 mm^1,R=0.0522 and wR=0.1358 for 5611 independent reflections(R(int)=0.0778)and 5169 observed ones(I>2σ(I)).
基金supported by State Key Program of National Natural Science Foundation of China (grant number 81430095)
文摘Monosaccharides are one of the most important structural components of biomolecules, such as polysac- charides, nucleic acids, glycolipids and glycoproteins. In structural analysis of polysaccharides and gly- coconjugates, the absolute configurations （D or L） of the constituent monosaccharides are usually deter- mined by measurement of the optical rotation, CD spectra or characteristic chromatographic retention behavior. However, each method has its unique advantages and limitations which should be considered while using them. In this review, an overview of the different methods for the determination of absolute configuration of monosaccharides and their underlying principles are summarized to serve as a reference for researchers.
基金This work was supported by the National Natural Science Foundation of China.
文摘Since two asymmetric centres are usually present in the bisbenzylisoquinolines,the circular dichroism is known to be an important method to elucidate their stereochemistry.We studied the relationships of the CD spectra with the stereochemistry of synthetic RR-(1),SS-(2),RS-daurisoline(3) and SR-daurisoline(4).By comparision of the CD spectrum of natural daurisoline(1)from Menis- permum dauricum(Menispermaceae)with those of synthetic enantiomers,the absolute configuration was established as RR-daurisoline(1).
基金supported by National Key R&D Program of China(No.2022YFC2804100)Qingdao Marine Science and Technology Center(No.2022QNLM030003-1)+2 种基金Qingdao postdoctoral project(No.QDBSH20240102034)Shandong Postdoctoral Science Foundation(No.SDCX-ZG-202400077)National Natural Science Foundation of China(No.U2006204)。
文摘Ten previously undescribed rearranged 4,9-friedodrimane merosesquiterpenoids,designated ircinrimanes A-J(1-10),were isolated from the marine sponge Ircinia sp.,collected from the South China Sea.Their structures and absolute configurations were definitively elucidated through a combination of spectroscopic data analysis,DP4+probability assessments,electronic circular dichroism(ECD)calculations,and Mo2(OAc)4 experiment.Compounds 1-4contained benzene rings,with compound 1 featuring an unusual 2-carbonyl morpholin ring,while compound 2 possessed a benzoxazole ring.Compounds 5-9 comprised sesquiterpenoid quinones with distinct amino side chains at C-20,and compound 10 incorporated an ethoxy side chain.Notably,compounds 1-10 demonstrated an unusual rearrangement of 4,9-friedodrimane sesquiterpenes.Compounds 2,5-8 and 10 demonstrated cytotoxic activity,while compound 2 exhibited anti-inflammatory activity in zebrafish.
文摘Two new ent-rosane type diterpenoids, anomalusins A （1） and B （2）, together with ten known compounds were isolated from the plants of Mallotus anomalus Meer et Chun. The structures of compounds 1 and 2 were fully elucidated on the basis of spectroscopic evidence, and CD analysis.
基金financially supported by the National Natural Science Foundation of China(Nos.81322051 and 31400300)the Natural Science Foundation of Jiangsu Province(No.BK20151442)the Project Funded by the Priority Academic Program Development(PAPD) of Jiangsu Higher Education Institutions
文摘Two cyclopeptides, celogentin L(1) and its epimer lyciumin A(2) were firstly isolated from Celosia argentea L.. The planar structures of the two compounds were fully determined by spectroscopic data, including 1 D-, 2 D-NMR, and HR-ESI/MS. The absolute configurations of amino acid components were assigned via chiral-phase HPLC analyses after acid hydrolysis. Furthermore, the configuration of C-N linkage at the glycine Cα was elucidated by extensive analyses of 2 D-NMR and comparison of the experimental and calculated electronic circular dichroism(ECD) spectra. Cytotoxicity of the two compounds against human alveolar epithelial A549, hepatocellular carcinoma Hep G2, and cervical cancer Hela cell lines was assayed. Although both of them were inactive in these cells, the present findings add new facets for the chemistry of Celosia argentea.
