isolated nucleic acid molecules cloned from artemisia annua encode artemisinic aldehyde double bond reductase and artemisinic / dihydroartemisinic aldehyde dehydrogenase . artemisinic aldehyde double bond reductase enzymatically reduces artemisinic aldehyde to dihydroartemisinic aldehyde . artemisinic / dihydroartemisinic aldehyde dehydrogenase enzymatically oxidizes dihydroartemisinic aldehyde to dihydroartemisinic acid and artemisinic aldehyde to artemisinic acid . the nucleic acid molecules , and the enzymes encoded thereby , may be used in processes to produce dihydroartemsinic aldehyde , dihydroartemisinic acid or artemisinic acid in a host cell . dihydroartemisinic acid is a late precursor to the a antimalarial compound artemisinin .