ABSTRACT
Seven new triterpenoid saponins, including five ursane-type saponins, ilexchinenosides R-V (1-5), and two oleanane-type saponins, ilexchinenosides W-X (6-7), with four known triterpenoid saponins (8-11) were isolated from the leaves of Ilex chinensis. Their structures were elucidated by comprehensive spectroscopic 1D and 2D NMR and HR-ESI-MS data. Their sugar moieties were determined by HPLC analysis compared with standards after hydrolysis and derivatization. Compounds 1, 2, 4, 9 and 10 exhibited potential hepatoprotective activity against N-acetyl-p-aminophenol (APAP)-induced HepG2 cell injury in vitro.
ABSTRACT
Nowadays, the NMR technique is widely used to determine the structures of chiral compounds. This paper summarizes some new methods which have been applied to determine the relative configurations of compounds with chain structure. The NMR spectra can provide coupling constants, chemical shifts of1H and13C which are favorable for assigning relative configurations of complicated compounds. Specifically, systematical coupling constants can determine the relative configurations of structures that contain 1, 2-dimethines, 1, 3-dimethines and γ-amino-β-hydroxyl-α-methylene carboxylate moiety. Chemical shifts of proton signal can assign the relative configurations of compounds which possess 1, 3-diols, α-alkyl-β-hydroxyl alkone and 1, 3, n- methyl-branched carbon. Chemical shifts of carbon signal can ascertain 1, 3-diols’ relative configurations.