2,4,6,8,10,12,14,16-Heptadecaoctaenoic acid,2,6,11,15-tetramethyl-17-(2,6,6-trimethyl-1-cyclohexen-1-yl)-,3-hydroxy-2-[[6-(methylseleno)-1-oxohexyl]oxy]propyl ester,(2E,4E,6E,8E,10E,12E,14E,16E)-