1,4,5-Trihydroxy-7-methoxy-9H-fluoren-9-one, a new cytotoxic compound from Dendrobium chrysotoxum.

A new compound, 1,4,5-trihydroxy-7-methoxy-9H-fluoren-9-one, has been isolated together with two known fluorenones, dendroflorin and denchrysan A, from the whole plant of Dendrobium chrysotoxum, a plant of Dendrobium genus, used as a health-food. The structure of the fluorenones has been determined on the basis of spectroscopic studies. The isolated compounds were evaluated in vitro for their inhibitory ability against the growth of human leukaemia cell lines K562 and HL-60, human lung adenocarcinoma A549, human hepatoma BEL-7402 and human stomach cancer SGC-7901. All three fluorenones displayed selective cytotoxicity against BEL-7402 with IC50 values of 1.49, 0.97 and 1.38μg/ml, respectively.