Saccharosporones A, B and C, cytotoxic antimalarial angucyclinones from Saccharopolyspora sp. BCC 21906.

Three new angucyclinones, saccharosporones A, B and C, together with (+)-ochromycinone, (+)-rubiginone B2, tetrangulol methyl ether and fujianmycin A, were obtained from fermentation of the terrestrial actinomycete of the genus Saccharopolyspora BCC 21906 isolated from a soil collected in Chanthaburi Province, Thailand. Structures of the new compounds and their relative configurations were assigned by NMR spectral data interpretation. Saccharosporones A and B exhibited antimalarial activity against Plasmodium falciparum K1 with IC50 values of 4.1 and 3.9 μM. Both metabolites also possessed cytotoxic activities against cancer cell lines (KB, MCF-7 and NCI-H187) and nonmalignant Vero cell, while saccharosporone C only showed cytotoxic activity against NCI-H187.