Three new polyketides isolated from the Karst cave-derived Streptomyces sp. FD-2-6

Three new polyketides, actinofuranones J (1) and K (2), nocapyrone S (3), with one known compound nocapyrone Q (4) were isolated from the culture broth of a Karst cave-derived Streptomyces sp. (FD-2-6). Their structures were elucidated by comprehensive analysis of NMR spectroscopic data, HR-MS and electronic circular dichroism (ECD) data. The antitumour and antibacterial activities of 1-4 were investigated by examining their IC₅₀ and MIC values in MCF-7 human breast cancer cells, human hepatocellular carcinoma HepG2 cells and human cervical cancer Hela cells, and Klebsiella pneumoniae sp, Pseudomonas aeruginosa sp, Mycolicibacterium smegmatis sp, Escherichia coli sp, Staphylococcus aureus sp. Compounds 1-4 showed weak inhibitory effect on antitumour activity on MCF-7 human breast cancer cells, and human cervical cancer Hela cells.