(2E,10E,12E,16Z,18E)-6-(Acetyloxy)-17-ethyl-3,5,7,9,11,15-hexamethyl-19-(3-methyl-6-oxo-3,6-dihydro-2H-pyran-2-yl)-8-oxononadeca-2,10,12,16,18-pentaenoic acid AIDS-072917 AIDS072917 Leptomycin derivative