Propanoic acid, 2,2-dimethyl-, (1S,3S,5Z,7R,8E,11S,12S,13E,15S,17R,21R,23R,25S)-1,11,12,21-tetrahydroxy-17-(1R)-1-hydroxyethyl-5,13-bis(2-methoxy-2-oxoethylidene)-10,10,26,26-tetramethyl-19-oxo-18,27,28,29-tetraoxatetracyclo21.3.1.13,7.111,15nonacos-8-en-