The biflavones 7,7"-dimethyllanaraflavone (1), agathisflavone (2), and 7"-methylagathisflavone (3) isolated from the leaves of
Ouratea
and luxenchalcone (4) isolated from the leaves and branches of
Luxemburgia
, as well as a mixture of 7,7"-dimethyllanaraflavone and 7"-methylagathisflavone, were assayed against HT-29 colon adenocarcinoma, NCl-H460 non-small cell lung carcinoma, MCF-7 breast cancer cell, OVCAR-3 ovarian adenocarcinoma cells, and RXF-393 renal cell carcinoma. The results show significant activities, particularly for 7,7"-dimethyllanaraflavone (IC
50 0.77 ± 0.08, 2.42 ± 0.22, and 2.59 ± 0.32 mg/ml for NCl-H460, MCF-7, and OVCAR-3, respectively), and for 7"-methylagathisflavone (IC
50 values of 4 mg/ml). Luxenchalcone revealed significant cytotoxicity on the five cell lines tested.