(9alpha,10beta,12alpha)-5,16-Bis(isopropylsulfanylmethyl)-9,12-epoxy-10-hydroxy-9-methyl-1-oxo-2,3,9,10,11,12-hexahydro-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]benzodiazocine-10-carboxylic acid methyl ester