4'-(4''-Isovaleroylmycarosyl)mycaminosyltylonolide 74290-44-1 Antibiotic N 1 BRN 4641946 Tylosin, 23-di-O-de(6-deoxy-2,3-di-O-methyl-beta-D-allopyranosyl)-, 3-acetate-4B-(3-methylbutanoate)-