(1′R,2S,3′R,8′R,12′Z,18′Z,20′Z,24′S,25′S,27′R)-27′-Hydroxy-5′,13′,25′-trimethyl-11′H,17′H,22′H-spiro[oxirane-2,26′-[2,10,16,23]tetraoxatetracyclo[22.2.1.0~3,8~.0~8,25~]heptacosa[4,12,18,20]tetraene]-1 1′,17′,22′-trione