Chicamycin A

Structures of chicamycins A and B have been determined from a series of chemical degradation studies coupled with spectroscopic analysis. Chicamycin A is 2(S),11(R), 11a (S)-1,2,3,10, 11, 11a -hexahydro-2,8-dihydroxy-7,11-dimethoxy-5H-pyrrolo-[2,1-c] [1,4]-benzodiazepin-5-one, and chicamycin B is 2(S), 11a (S)-1,2,3, 11a -tetrahydro-2,8-dihydroxy-7 -methoxy-5H-pyrrolo-[2,1-c][1,4]-benzodiazepin-5-one which is the demethanol form of chicamycin A. The structure of chicamycin B is closely related to that of neothramycin , differing only in the position of a hydroxyl substituent on the pyrrolidine ring.

Chicamycin is a new antitumor antibiotic produced by a strain of Streptomyces albus, No. J576 -99. The antibiotic is extractable into organic solvents from the fermentation broth and is obtained in two active forms, chicamycins A and B, depending upon the isolation procedure used. Chicamycin A is not a natural antibiotic but the methanol adduct of naturally produced chicamycin B. Both forms of the antibiotic have weak antibacterial activity against some Gram-positive and acid-fast bacteria. They inhibit the growth of experimental tumors such as P388 mouse leukemia.