21411-53-0 8,9,14,15,24,25-Hexahydro-14-hydroxy-4,12-dimethyl-3-(1-methylethyl)-3H-21,18-nitrilo-1H,22H-pyrrolo[2,1-c][1,8,4,19]dioxadiazacyclotetracosine-1,7,16,22(4H,17H)-tetrone NSC244426 OSTREOGRYCIN A Vernamycin A Virginiamycin Factor M1 Virginiamycin M1