Ophiorrhines F and G, Key Biogenetic Intermediates of Ophiorrhine Alkaloids from <i>Ophiorrhiza japonica</i> and Their Immunosuppressant Activities
Bao‐Bao Shi, Hong‐Lian Ai, Kai-Ting Duan, Tao Feng, Ji‐Kai Liu
Abstract
Continued interest in bioactive alkaloids led to the isolation of two undescribed alkaloids, ophiorrhines F (1) and G (2), from the aerial parts of Ophiorrhiza japonica. Their structures were elucidated based on spectroscopic methods, electronic circular dichroism, and calculated NMR with DP4+ analysis. These two alkaloids represent key biological genetic intermediates in the formation of ring C in the ophiorrhines. Compound 1 exhibited good inhibition on LPS-induced B cell proliferation with an IC50 value of 0.38 μM and showed significant selective inhibitory activity on a B cell proliferation response with a selective index of 548.42. A preliminary study indicated that 1 may have a new mechanism of immunosuppression.