(1′S,2S,3′R,6S,7′R,8′Z,15′S,16′R,17′R,18′R,19′S,20′S,21′R,22′Z,26′S,30′S)-3′,15′,16′,17′,18′,20′,21′-Heptahydroxy-6-[(2S)-2-hydroxybutyl]-5′,5′,15′,19′,21′,30′-hexamethyl-3,4,5,6-tetrahydro-24′H-spiro [pyran-2,28′-[4,25,29]trioxatricyclo[24.3.1.0~3,7~]triaconta[8,22]dien]-24′-one