High Peroxidase Activity In Cell Cultures ofArtemisia AnnuaWith Minute Artemisinin Contents

Abstract
In callus and cell suspension cultures of Artemisia annua minute amounts of artemisinin were found. In these cultures, a high peroxidase activity was measured, intracellularly and, especially, in the medium. In vitro, artemisinin rapidly decomposed when incubated with a cell homogenate of A. annua or with spent culture medium, as well as in a solution of commercially obtained horseradish peroxidase (EC 1.11.1.7). In contrast, the peroxidase activity in the intact plant, containing considerable amounts of artemisinin, was low. We suggest that the high peroxidase activity in A. annua cell cultures contributes to their very low artemisinin contents.