Toonanoronoids A-E, five new limonoids from Toona ciliate var. yunnanensis.

Five new B-seco-limonoids, namely toonanoronoids A-E (1-5), in conjunction with three previously reported compounds, were isolated from the EtOAc extract of the twigs and leaves of Toona ciliata var. yunnanensis. Their structures were elucidated through comprehensive spectroscopic and X-ray crystallographic analysis. The cytotoxic activities of new compounds against five human tumor cell lines (HL-60, SMMC-7721, A549, MCF-7, and SW480) were screened, Compounds 4 and 5 exerted inhibition toward two tumor cell lines (HL-60, SW-480) with IC50 values between 1.7 and 5.9 μM.