Is polyamine biosynthesis a possible site of action of cinmethylin and artemisinin?

Abstract

The effects of artemisinin, a naturally occurring sesquiterpene lactone, and the structurally similar herbicide cinmethylin on polyamine production were examined in seedings of lettuce, corn, and pea. Although the antimalarial activity of artemisinin in animal cell cultures is associated with a dramatic reduction in the concentration of putrescine, results presented here indicate plants treated with growth-inhibiting concentrations of artemisinin or cinmethylin generally display only slightly reduced endogenous levels of putrescine and spermidine. In addition, simultaneous addition of 0.5 m M putrescine to artemisinin- or cinmethylin-treated excised corn and pea root cultures could not prevent a reduction in root growth. Similarly, the addition of putrescine to artemisinintreated lettuce seedlings did not protect against artemisinin-induced chromosome decondensation. These results suggest that the primary biochemical activity of cinmethylin and artemisinin, which leads to inhibition in root growth, does not involve a block in the polyamine biosynthetic pathway.