Antimalarial and antituberculosis substances from Streptomyces sp. BCC26924

Two new carbazomycin dimers (6 and 7) and 3-hydroxy-1,2-dimethyl-2,3-dihydro-1H-carbazol-4-one (9) together with six known compounds, carbazomycins A-D, cyclomarin C, and pimprinine have been isolated from Streptomyces sp. BCC26924. Carbazomycins B, C, and cyclomarin C exhibited antimalarial activity (against Plasmodium falciparum, K1 multi-drug resistant strain) with IC50 in a range of 0.24-2.37 μg/mL. Cyclomarin C exhibited anti-TB activity with a minimum inhibitory concentration value of 0.10 μg/mL, while carbazomycin D, compound 7, and pimprinine displayed MIC values in a range of 12.5-25.0 μg/mL. In addition, compounds 2, 5, 6, and 7 showed weak cytotoxicity against cancerous (MCF-7, KB, NCI-H187) and non-cancerous (Vero) cells.