Biologically active metabolites from Xenorhabdus spp., Part 2. Benzopyran-1-one derivatives with gastroprotective activity.

Two novel antibiotic compounds, named xenocoumacins 1 [2] and 2 [3], with potent antiulcer activity were isolated from cultures of Xenorhabdus spp. Both compounds exhibit antibacterial activity and potent antiulcer activity against stress-induced ulcers when dosed orally. In addition, 2 has antifungal activity. Their chemical structures were determined by extensive 1H-nmr, 13C-nmr, and mass spectral studies to be 3,4-dihydro-8-hydroxy-1H-2-benzopyran-1-one derivatives.