Cephalotaxine-type alkaloids with antiproliferation effects from the branches and leaves of Cephalotaxus fortunei var. alpina

Eight cephalotaxine-type alkaloids (1–8), including two new compounds cephafortunines A and B (1–2), were isolated from the branches and leaves of Cephalotaxus fortunei var. alpina. Their structures were identified by a series of spectroscopic methods (MS, UV, IR, 1D, and 2D NMR) and comparison with the reported data of known analogs. The absolute configurations of 1 and 2 were determined by electronic circular dichroism (ECD) calculations. 1–8 were evaluated for their in vitro antiproliferation effects against two human leukemia cell lines (U937 and HL-60). All compounds showed different levels of antiproliferation effects against U937 cells with GI50 values of 4.21–23.70 μM. 4 and 5 were the most active against U937 cells with GI50 values of 4.21 and 6.58 μM and against HL-60 cells with GI50 values of 6.66 and 6.70 μM, respectively. 4 and 5 arrested HL-60 cell cycle in G0/G1 phase.