Synonyms: MilbemycinB, 28-deoxy-6,28-epoxy-22-hydroxy-26-[(2-methyl-1-oxo-2-butenyl)oxy]-25-(1-methyl-1-propenyl)-,[6R,22R,25S(E)]-;Spiro[11,15-methano-2H,13H,17H-furo[4,3,2-pq][2,6]benzodioxacyclooctadecin-13,2'-[2H]pyran],milbemycin B deriv.; Antibiotic VM 44865; VM 44865