Plant anticancer agents. IX. Constituents of Hyptis tomentosa.

The twigs, leaves, and flowers of Hyptis tomentosa were found to owe their major cytotoxic activity to the presence of desoxypodophyllotoxin (4), but the two weakly cytotoxic flavones 5-hydroxy-4',6,7,8-tetramethoxy flavone (3) and 5-hydroxy-4',3,6,7,8-pentamethoxy flavone (2) also contributed to the total cytotoxicity of the crude extracts. The flavones eupatorin (6) and 5-hydroxy-3',4',6,7-tetramethoxy flavone (5) were isolated as inactive constituents, together with the lignan sesamin (1).