Novel oxidized derivatives of antifungal pyrrolnitrin from the bacterium Burkholderia cepacia K87

The screening of antifungal active compounds from the fermentation extracts of soil-borne bacterium Burkholderia cepacia K87 afforded pyrrolnitrin (1) and two new pyrrolnitrin analogs, 3-chloro-4-(3-chloro-2-nitrophenyl)-5-methoxy-3-pyrrolin-2-one (2) and 4-chloro3-(3-chloro-2-nitrophenyl)-5-methoxy-3-pyrrolin-2-one (3). Pyrrolnitrin showed strong antifungal activity against Rhizoetonia solani but the analogs (2 and 3) were found to be marginally active. The isolates, 2 and 3, are believed to be biodegraded derivatives of pyrrolnitrin.