Fig. 1: Tanshinones and partial biosynthetic pathway in Danshen.

a Structures of the major tanshinone constituents of Danshen: tanshinone IIA, tanshinone I, cryptotanshinone (1) and 15,16-dihydrotanshinone I (2). b Elucidated steps for tanshinone biosynthesis in Danshen.