Antimycotic effects of the novel antitumor agents fostriecin (CI-920), PD 113,270 and PD 113,271

The novel fermentation products fostriecin and analogs PD 113,270 and PD 113,271 are structurally related polyene lactone phosphates that have antitumor activity in vitro and in vivo. They have no Antibacterial effects, but they were inhibitory to yeasts (agar diffusion method) with MICs of 3 approximately 300 micrograms/ml. Fostriecin or its analogs were active vs. 29 of 46 yeast species (11 genera). Ten of 12 cultures of Candida sp. were not sensitive to any of the analogs, while 11 of 14 cultures of Saccharomyces sp. were inhibited by one or more of the agents. Sensitivity patterns were of three types: Twelve cultures were sensitive only to PD 113,270; fostriecin and PD 113,271 (but not PD 113,270) were active vs. 7 cultures; and 9 cultures were sensitive to all three compounds. Dephosphorylation of the compounds resulted in the loss of antimycotic effects. Activity vs. the yeasts was related to studies of uptake and activity against Cancer cells.