Skip to main content
. 2013 Nov 19;8(11):e80464. doi: 10.1371/journal.pone.0080464

Figure 1. Biosynthetic pathway of tanshinone compounds.

Figure 1

The solid arrows denote known steps and the dashed arrows denote hypothetical steps. Modified from Ma et al. and Gao et al. [7,13]. Enzymes of 2-C-methyl-D-erythritol 4- phosphate (MEP) pathway are follows: 1-deoxy-D-xylulose-5-phosphate synthase (DXS), 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase (MCT), 4-diphosphocytidyl-2-Cmethyl-D-erythritol kinase (CMK), 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase (MDS), 4-hydroxy-3-methylbut-2-enyl diphosphate synthase (HDS), 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (HDR); and enzymes of mevalonate (MVA) pathway are acetyl-CoA acetyltransferase (AACT), 3-hydroxy-3-methylglutaryl-CoA synthase (HMGS), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), mevalonate kinase (MVK), 5-phosphomevalonate kinase (PMK) and 5-diphosphomevalonate decarboxylase (PMD). Isopentenyl diphosphate isomerase (IPPI) catalyzes the isomerisation of dimethylallyl dihosphate (DMAPP) to isopentenyl diphosphate (IPP) whereas conversion of IPP to geranylgeranyl diphosphate (GGPP) is catalysed by geranylgeranyl diphosphate synthase (GGPPS). Hypothetical tanshinones biosynthetic pathway was deduced by the consideration of identified diterpenoid natural products from S. miltiorrhiza [56,57]. These steps involve series hydroxylation, dehydrogenation and reduction reactions catalysed by cytochrome P450s, dehydrogenases and reductases.