PD 118,576: a new antitumor macrolide antibiotic.

The isolation and properties of PD 118,576, a new cytotoxic antibiotic obtained from the culture broth of a Streptomyces sp., are described. The structure of this compound was established by spectral analyses of the parent compound and its tri-O-acetyl derivative. PD 118,576 proved to be related to the bafilomycins and therefore is a new member of this recently discovered family of macrolide antibiotics.