An approach for distinguishing two types of positional isomers of dimeric shikonin and its analogs was explored with ^(4)JC,H long-range correlation by prolonging the acquisition time at ^(2,3)JC,H values of 2.0 and 8...An approach for distinguishing two types of positional isomers of dimeric shikonin and its analogs was explored with ^(4)JC,H long-range correlation by prolonging the acquisition time at ^(2,3)JC,H values of 2.0 and 8.0Hz.Furthermore,the ^(1)H(proton)nuclear magnetic resonance(NMR)pattern of phenolic hydroxyl protons was developed as a“diagnosis signal”to ascertain the relative location of each side chain in DMSO-d_(6) at sample concentrations of 0.022-0.034 mol/L.The chemical shift differences of 0.6ppm between OH-5' and OH-1 and between OH-8'and OH-4 are assigned to Type A and Type B,respectively.All reported ambiguous structures were corrected by this pattern.Additionally,the steric structures of isolated compounds were elucidated by quantum chemical calculations of electronic circular dichroism(ECD)spectra.展开更多
Arnequinol A(1),featuring an unprecedented 6/6/3 tricyclic carbon skeleton fused with a heptatomic oxo-bridge,together with arnequinone A(2)bearing a highly conjugated methyl-shifting benzogeijerene skeleton,were isol...Arnequinol A(1),featuring an unprecedented 6/6/3 tricyclic carbon skeleton fused with a heptatomic oxo-bridge,together with arnequinone A(2)bearing a highly conjugated methyl-shifting benzogeijerene skeleton,were isolated from Arnebia euchroma.Their structures were elucidated by extensive spectro-scopic methods and quantum chemical calculations of the 13 C nuclear magnetic resonance(NMR)data and electronic circular dichroism(ECD)spectra.The plausible biosynthetic pathways for 1 and 2 were presented.In in vitro test,compound 2 showed potent neuroprotective activity against serum-deprivation induced PC12 cell damage at a concentration of 10μmol/L.展开更多
基金funded by the CAMS Innovation Fund for Medical Sciences(CIFMS,No.2021-I2M-1-028).
文摘An approach for distinguishing two types of positional isomers of dimeric shikonin and its analogs was explored with ^(4)JC,H long-range correlation by prolonging the acquisition time at ^(2,3)JC,H values of 2.0 and 8.0Hz.Furthermore,the ^(1)H(proton)nuclear magnetic resonance(NMR)pattern of phenolic hydroxyl protons was developed as a“diagnosis signal”to ascertain the relative location of each side chain in DMSO-d_(6) at sample concentrations of 0.022-0.034 mol/L.The chemical shift differences of 0.6ppm between OH-5' and OH-1 and between OH-8'and OH-4 are assigned to Type A and Type B,respectively.All reported ambiguous structures were corrected by this pattern.Additionally,the steric structures of isolated compounds were elucidated by quantum chemical calculations of electronic circular dichroism(ECD)spectra.
基金supported by the CAMS Innovation Fund for Medical Sciences(No.2016-I2M-1-010,China).
文摘Arnequinol A(1),featuring an unprecedented 6/6/3 tricyclic carbon skeleton fused with a heptatomic oxo-bridge,together with arnequinone A(2)bearing a highly conjugated methyl-shifting benzogeijerene skeleton,were isolated from Arnebia euchroma.Their structures were elucidated by extensive spectro-scopic methods and quantum chemical calculations of the 13 C nuclear magnetic resonance(NMR)data and electronic circular dichroism(ECD)spectra.The plausible biosynthetic pathways for 1 and 2 were presented.In in vitro test,compound 2 showed potent neuroprotective activity against serum-deprivation induced PC12 cell damage at a concentration of 10μmol/L.
