| abstract |
Compounds of formula (I), wherein R1 and R2 are independently hydrogen, unsubstituted lower alkyl or lower alkyl substituted by lower alkoxy or lower alkyl thio, or acyl which is unsubstituted or substituted by one or more of lower alkyl, lower alkyl substituted by halogen, and lower alkoxy; X is CO or CHOH; Y is CO or CH2; and Z is O or NH, and epimers and enantiomers thereof, or the physiologically usable salts thereof are useful as anti-tumor agents. They can be prepared by fermentation of Aspergillus sp. and, optionally, subsequent modification of functional groups. |