(2E,10E,12E,16Z,18E)-6-(Acetyloxy)-9-[(acetyloxy)methyl]-17-ethyl-3,5,7,11,15-pentamethyl-19-(3-methyl-6-oxo-3,6-dihydro-2H-pyran-2-yl)-8-oxononadeca-2,10,12,16,18-pentaenoic acid AIDS-072920 AIDS072920 Leptomycin derivative