(2R)-2-[(2R,5S,6R)-6-((1S,2S,3S,5R)-5-{(2S,9S,10S,12R,15R)-2-[(2R,5R,6S)-5-ethyl-5-hydroxy-6-methyltetrahydro-2H-pyran-2-yl]-15-hydroxy-2,10,12-trimethyl-1,6,8-trioxadispiro[4.1.5.3]pentadec-9-yl}-2-hydroxy-1,3-dimethyl-4-oxoheptyl)-5-methyltetrahydro-2H-pyran-2-yl]butanoic acid