Artemisinin and its derivatives are recommended by the World Health Organization as first line treatment for malaria. The drug is administered as a combination therapy with other longer acting antimalarials (ACTs) to minimize the risk of parasite resistance. Because artemisinin is extracted from the sweet wormwood plant where it occurs in relatively small amounts (0.01-1% of dry weight, depending on the climate, plant variety and soil composition), it and its derivatives are relatively expensive and not always available, causing a substantial bottleneck in meeting demand for the over 49 million courses (WHO 2008) of ACTs each year.