Ming Zhou,Xiaogang Peng,Jia Zhou,Ye Liu,Xianggao Meng,Hanli Ruan
Six undescribed triterpenoids , schincarins A‒F, categorized as the preschisanartane (schincarin A), 3,4-secocycloartane (schincarins B‒D), 3,4; 9,10-disecocycloartane (schincarin E), and 3,4-secolanostane (schincarin F) classes, along with twelve known analogues, were obtained from the stems and leaves of Schisandra incarnata Stapf. Their structures were elucidated on the basis of extensive spectroscopic analyses. The absolute configuration of schincarin A was corroborated by analysis of the experimental ECD spectrum, and single-crystal X-ray diffraction with Mo K α irradiation. Schincarin A represented the first example of preschisanartane-type triterpenoid with two oxa-bridged hemiketals . Among the selected compounds which were evaluated for immunosuppressive activities, schincarin C and kadsudilactone A showed potential inhibition against ConA-induced T-cell proliferation with IC 50 values of 5.83 and 6.32 μ M, and LPS-induced B cell proliferation with IC 50 values of 10.21 and 11.49 μ M, respectively.
In this study, incartrilactones A ( 1 ) and B ( 2 ), two previously undescribed schinortriterpenoids (SNTs) possessing an unprecedented 5/5/6/5/7/5-fused hexacyclic skeleton, together with one previously undescribed ( 3 ) and one known ( 4 ) analogues, were isolated from the stems of Schisandra incarnata Stapf. Their structures with absolute configurations were determined by comprehensive spectroscopic analysis, X-ray crystallography and electronic circular dichroism calculation. Compounds 1 and 2 represent the first class of 14,15-seco-15,17-cyclolancifoartane-type SNTs containing the unusual linkage of ‒C14‒C16‒C13‒C17‒C15. The hypothetical biogenetic pathway of compounds 1 and 2 was postulated. Compounds 1 and 2 exhibited potent α -glucosidase inhibitory activity with IC 50 values of 133.1 and 165.3 μM, representing that they were more active than the positive control, acarbose (IC 50 = 232.8 μM). Compound 4 showed moderate in vitro immunosuppressive effect against ConA-induced T cell and LPS-induced B cell proliferation, with IC 50 values of 35.3 ± 0.9 μM and 24.9 ± 0.6 μM, respectively. The cytotoxicity of compounds 1 − 4 against three human cancer cell lines was also tested, with no obvious cytotoxicity being observed.
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