Biogenetic Synthesis of Qinghaosu

Based on the consideration that there are some plausible biogenetic relationships among three major compositions 1, 20, and 10 in qinghao, Huang et al. and Wang et al. succeeded in the incorporation of MVA into 20 in qinghao and then realized the biotransformation of 20 into 1 and 10 in the homogenate. 

Since then, several laboratories also report in their research that artemisinic acid (20) is confirmed to be the biogenetic intermediate of qinghaosu, and dihydro-artemisinic acid (23) can also be biotransferred to qinghaosu. Furthermore, on incubation with the cell-free extracts of qinghao leaves, 20 can also be transferred into 10 and in turn 10 as well as dihydro-10 can be transferred to qinghaosu. 

Therefore, they conclude that 10 is the biosynthesis precursor of qinghaosu, but it has not been mentioned whether 10 is the necessary intermediate for the biosynthesis 

It is unclear whether the different conclusions about the role played by 

10 come from the different experimental conditions, the isotopic-labeled precursor 

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