Yeppoonic acids A - D: 1,2,4-trisubstituted arene carboxylic acid co-metabolites of conglobatin from an Australian Streptomyces sp.

Streptomyces sp. MST-91080 was isolated from a soil sample collected in Queensland, Australia. From this strain, yeppoonic acids A - D were purified and spectroscopically characterised. The yeppoonic acids are a family of diene enecarboxylic acids on a 1,2,4-trisubstituted benzene scaffold, structurally related to other Streptomyces secondary metabolites MF-EA-705α/β, NFAT-133 and the lorneic acids. Yeppoonic acids B and C show strong cytotoxicity against the NS-1 mouse myeloma cell line (IC 2.3 µg ml and 3.8 µg ml, respectively) and moderate activity against the DU 145 human prostate cancer cell line (IC 32.8 µg ml and 49.6 µg ml, respectively).