Isolation and bioactivity of new tanshinones

Two new diterpenoids, designated neocryptotanshinone and isotanshinone IIB, have been isolated from "Tan-Shen," the root of Salvia miltiorrhiza, together with a known compound, danshexinkun A. Their structures are established by spectral and physical data. Isotanshinone IIB exhibits significant inhibitory activity in vitro on ADP- and collagen-induced aggregation.