4-Oxo-4-{[(1R,4S,5R,8S,9R,10R,12R,13R)-1,5,9-trimethyl-11,14,15,16-tetraoxatetracyclo[10.3.1.0~4,13~.0~8,13~]hexadec-10-yl]oxy}butanoic acid [ 182824-33-5 ]