The natural dithiolopyrrolone antibiotics. produced during fermentation by Saccharothrix algeriensis NRRL B-24137, are known for their potent antibacterial, antifungal, and anticancer activities. During dithiolopyrrolone biosynthesis, the activated organic acid (acyl-CoA) is incorporated into the pyrrothine nucleus. We investigated the use of precursor-directed biosynthesis (PDB) to create new dithiolopyrrolone analogs by substitution of several organic acids in place of the usual organic acid. No other study on dithiolopyrrolone production by precursor-directed biosynthesis has been reported. The production of four novel dithiolopyrrolones in the presence of benzoic, valeric and cinnamic acids by S. algeriensis was obtained in this study. The mass spectrometry data showed a direct incorporation of added valeric and benzoic acids to form several dithiolopyrrolone analogs. However, addition of all other organic acids did not lead to the production of the corresponding dithiolopyrrolone analogs. We describe here the use of the PDB process for production of four new dithiolopyrrolone analogs, valeryl-pyrrothine, benzoyl-pyrrothine, demethyl-benzoyl-pyrrothine and formoyl-pyrrothine. (C) 2008 Elsevier Ltd. All rights reserved.