Hapalindole-related alkaloids from the cultured cyanobacterium Fischerella ambigua

Four hapalindole-related alkaloids namely fischambiguines A and B ambiguine P ambiguine Q nitrile as well as ambiguine G nitrile were identified from the cultured cyanobacterium Fischerella ambigua (UTEX 1903) The structures were determined by spectroscopic analysis including MS 1D and 2D NMR and Xray crystallography The alkaloids possessed fused pentacyclic and hexacyclic carbon skeletons Fischambiguine B displayed a strong inhibitory activity against Mycobacterium tuberculosis with an MIC value of 2 mu M with no detectable cytotoxicity in a Vero cell line (C) 2010 Elsevier Ltd All rights reserved