(2E,4Z,8E)-(6S,7R,10S,11R,12S,14S,15R)-15-(2,5-Dimethoxy-3-nitro-phenyl)-11,12,15-trimethoxy-7-(4-methoxy-benzyloxy)-2,6,8,10,14-pentamethyl-pentadeca-2,4,8-trienoic acid ethyl ester