87913-35-7 Antibiotic Tan 528A Awamycin Protostreptovaricin I, 10,25-didemethyl-21-hydroxy-10-(methoxycarbonyl)-19-O-methyl-25-(methylthio)- Protostreptovaricin-31-oic acid, 25-demethyl-21-hydroxy-19-O-methyl-2S-(methylthio)-, methyl ester TAN 528A