Phytotoxins Produced by the Plant Pathogenic Fungus Bipolaris bicolor El-1.

Four phytotoxic compounds (1-4) were obtained from a culture of Bipolar is bicolor E1-1, a fungal pathogen of gramineous plants. Compounds 1-3 were respectively identified as cochlioquinone A, cochlioquinone B, and stemphone by spectrometric analyses. Compound 4, named isocochlioquinone A, was found to have an identical molecular formula to that of 1 and was determined to be an intramolecular redox isomer of 1. Compounds 1-4 inhibited the root growth of such plant seedlings as finger millet and rice.