Two New Diphenylethylenes from Arundina graminifolia and Their Cytotoxicity

Two new diphenylethylenes, gramniphenols H and I (1 and 2), together with six known diphenylethylenes (3-8), were isolated from Arundina graminifolia. The structures of 1-8 were elucidated by spectroscopic methods including extensive 1D- and 2D-NMR techniques. Compounds 1 and 2 were evaluated for their cytotoxicity against five human tumor cell lines. Compound 1 showed cytotoxicity against PC3 cells with IC50 value of 3.5 μM. Compound 2 showed cytotoxicity against NB4 and PC3 cells with IC50 values of 3.6 and 3.8 μM, respectively