Immunosuppressive alkaloids from Narcissus tazetta subsp. Chinensis and the mechanism of (+)-narciclasine in vitro and in vivo.

Three previously undescribed and sixteen known alkaloids were bioguidedly isolated from the bulbs of Narcissus tazetta subsp. chinensis (M.Roem.) Masamura & Yanagih. The structures were elucidated by spectroscopic data, including HRESIMS, NMR, and ECD. Eleven of the isolated alkaloids exhibited immunosuppressive activity on the proliferation of human T cells. (+)-Narciclasine (18) showed the most significantly suppressive activity with an IC 50 value of 14 ± 5 nM. In vitro , (+)-narciclasine (18) blocked NF-κB signal transduction, but did not affect PI3K/AKT signal transduction. What was more, (+)-narciclasine significantly reduced ALT and AST levels and alleviated liver damage induced by ConA in AIH mouse model. Study on immunosuppressive alkaloids from the bulbs of Narcissus tazetta subsp. chinensis. [Display omitted] • Three undescribed alkaloids with immunosuppressive activity on T cells were found. • The structures were elucidated by extensive spectroscopic analysis. • (+)-Narciclasine exhibited remarkable inhibition activity in vitro and in vivo. • Narcissus tazetta L. var. chinensis is a valuable immunosuppressant source. [ABSTRACT FROM AUTHOR]