Structure and biosynthesis of FD-594; a new antitumor antibiotic

The structure of a novel antitumor antibiotics FD-594 (1), produced by Streptomyces sp. TA-0256, was determined to have a glycosylated pyrano[4',3':6,7]naphtho[1,2-b]-xanthene skeleton by means of spectral data. The biosynthetic studies of the chromophore of 1 was also carried out by feeding experiments with [1-13C]-, [2-13C]-, and [1,2-13C2]sodium acetate. The labeling pattern was determined by 13C NMR including 2D INADEQUATE experiments, which allowed us to elucidate that the chromophore of 1 is derived from 14 acetate, followed by the loss of one carbon atom.