Hapalindole-related alkaloids from the cultured cyanobacterium Fischerella ambigua

Four indole alkaloids were identified from the cultured cyanobacterium Fischerella ambigua (UTEX 1903). Fischambiguine B (2) displayed a strong inhibitory activity against Mycobacterium tuberculosis with an MIC value of 2 μM, with no detectable cytotoxicity in a Vero cell line.