Background:

IC50: about 100 μM for binding of GST-BtkPH to PKC, about 30 μM for association of Btk with PKCbII, about 10 μM for JNK1 activity, and about 7 μM for TNF-a and about 3 μM for IL-2.

Terreic acid (TA), which was known as Aspergillus sp. No. Y-8980, was isolated from a soil sample abtained at Yoron Island of Kagoshima Prefecture.

Terreic acid is a quinone epoxide with antibiotic activity. At a mechanism view for its antibiotic action, it inhibits protein synthesis by blocking the formation of leucyl-tRNA in sensitive bacteria [1]. TA was also an inhibitor of Bruton’s tyrosine kinase (Btk) that blocks the PKC-Btk PH domain interaction. Btk plays core roles in mast cell activation and in B cell development [2].

In vitro: Terreic acid showed MIC (minimal inhibitory concentration) of 25 approximately 100 mcg/ml, 50 mcg/ml and 12.5 mcg/ml against Gram-positive and Gram-negative bacteria, Xanthomonas citri and Xanthomonas oryzae and, respectively. TA also showed anti-tumor effect in the concentrations of >6.25 mcg/ml on human carcinoma cells (HeLa cells) [1]. In lysates of HMC-1 human mast cells, TA can inhibit the binding of GST-BtkPH to PKC with an IC50 of