The Use of Artemisinin Compounds as Angiogenesis Inhibitors to Treat Cancer
By Qigui Li, Peter Weina and Mark Hickman
Artemisinin (ART) is a natural product of the plant Artemisia annua L. Reduction of ART yields the more active dihydroartemisinin (DHA), a compound which can be further converted to different derivatives, including, artesunate (AS) and artemether (AM), which are generally referred to as artemisinins (ARTs). ARTs are widely known for their potent antimalarial activity, but also been potential anti-cancer activity both in vitro and in vivo over the past few years. ARTs have inhibitory effects on cancer cell growth and also inhibit angiogenesis. Several studies have revealed that ART inhibits the growth of many transformed cell lines and has a selective cytotoxic effect. In one study, ART was shown to be more toxic to cancer than normal cells. In most of the systems, preloading of cancer cells with iron or iron-saturated holotransferrin triggers ART cytotoxicity with an increase in the activity of ARTs by 100-fold in some cell lines. It has been hypothesized that iron-activated ARTs induce damage by release of highly alkylating carbon-centered radicals and radical oxygen species (ROS). Radicals may play a role in the cell alterations reported in ARTs-treated cancer cells such as enhanced apoptosis, arrest of growth, inhibition of angiogenesis, and DNA damage. More studies have demonstrated that ART and its derivatives possess an anti-angiogenic activity (Li and Hickman, 2011).