Antimicrobial metabolites from a bacterial symbiont.

Two types of antibiotics, namely, indoles and dithiolopyrrolones, have been isolated and identified from Xenorhabdus bovienii A2. Compounds 1 and 2 showed strong activity against Cryptococcus neoformans, compounds 3 and 4 showed strong activity against Botrytis cinerea, and compounds 1, 3, and 4 showed significant activity against Phytophthora infestants (2 was not tested). In addition, two lower homologues of xenorhabdins 5 and 6, namely, 6-(N-3'-methylbutanamido)-4,5-dihydro-1,2-dithiolo[4,3-b]pyr rol-5- one [7] and 6-(N-butanamido)[4,5-dihydro-1,2-dithiolo[4,3-b]pyrrol-5-one [8], have been isolated and characterized for the first time.