The biflavones 7,7"-dimethyllanaraflavone (1), agathisflavone (2), and 7"-methylagathisflavone (3) isolated from the stems of Lonicera japonica and flavonoids (4) isolated from the stems and branches of Benincasa hispida, 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 1.77 ± 0.08, 3.42 ± 0.22, and 3.59 ± 0.32 mg/ml for NCl-H460, MCF-7, and OVCAR-3, respectively), and for 7"-methylagathisflavone (IC50 values of 4 mg/ml). Flavonoids revealed significant cytotoxicity on the five cell lines tested.