Investigations into the production and interconversion of phomoidrides A-D

structure: see text] Fermentation of ATCC 74256 led to the isolation and identification of C7 epimers of phomoidride A (CP-225,917) and phomoidride B (CP-263,114). We suggest the names phomoidrides C and D for these new fermentation products. Studies on the effect of pH on the distribution of phomoidrides A-D suggest phomoidride B (CP-263,114) is the first-formed secondary metabolite and the source of the remaining three phomoidrides.