Isocryptotanshinone is a potent signal transducer and activator of transcription 3 (STAT3) and protein tyrosine phosphatase 1B PTP1B inhibitor, with an IC50 of 56.1 μM for PTP1B.
It is showed that tanshinones significantly inhibited A549 proliferation and Isocryptotanshinone (ICTS) exhibits the strongest activity. Isocryptotanshinone inhibits the constitutive STAT3 and p-STAT3 (Y705) expression in concentration and time-dependent manners. Isocryptotanshinone dramatically inhibits the IL-6-stimulated expression of p-STAT3 (Y705) in a time-dependent manner[1].
[1]. Guo S, et al. Isocryptotanshinone, a STAT3 inhibitor, induces apoptosis and pro-death autophagy in A549 lung cancer cells. J Drug Target. 2016 Dec;24(10):934-942. [2]. Han YM, et al. PTP1B inhibitory effect of abietane diterpenes isolated from Salvia miltiorrhiza. Biol Pharm Bull. 2005 Sep;28(9):1795-7.