A method for treatment of hyperproliferative tissue which by exposing the hyperproliferative tissue to a sufficient quantity of a purified iridoid compound to inhibit its growth, where the iridoid compound includes a polysubstituted cyclopenta(c)dihydropyran where the cyclopenta ring is substituted at its 2′ position with a ketofuryl group, where the numbering of the fused cyclopenta(c)dihydropyran ring structure includes heterocyclic oxygen, is counterclockwise and begins at the first carbon atom counterclockwise from the cyclopenta ring so that oxygen is in the 2 position in the pyran ring. The invention also includes the mouse iridoid compounds.