57515-50-1 67-121 C Antibiotic 67-121 C Perimycin A, 21-O-(3-amino-3,6-dideoxy-4-O-beta-D-mannopyranosyl-beta-D-mannopyranosyl)-18-carboxy-21-O-de(4-amino-4,6-dideoxy-D-mannopyranosyl)-18-demethyl-13-deoxo-13-hydroxy-, cyclic 15,19-hemiacetal