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. Author manuscript; available in PMC: 2023 Apr 1.
Published in final edited form as: Curr Opin Plant Biol. 2022 Feb 20;66:102189. doi: 10.1016/j.pbi.2022.102189

Figure 4. Proposed tanshinone biosynthesis.

Figure 4.

Miltiradiene is produced from the general diterpenoid precursor GGPP by the successive action of SmCPS1 and SmKSL1, and undergoes presumably spontaneous oxidation to abietatriene. The ferruginol synthase (CYP76AH1, green), 11-hydroxyferruginol synthase (CYP76AH3, red), and 20-hydroxylase (CYP76AK1, blue) then catalyze successive hydroxylation reactions at C12, C11, C7, and C20, respectively. CYP71D375 (orange) is known to generate the 14,16-epoxy D-ring, which is then further oxidized to a furan ring by Sm2ODD14 (yellow). Compounds numbered as described in the text, while the shaded area indicates the linear pathway that seems to predominate in planta biosynthesis