(1E,2Z)-3-hydroxy-5,9,17-trioxo-4,5:9,10-disecoandrosta-1(10),2-dien-4-oate + H2O = 3-[(3aS,4S,7aS)-7a-methyl-1,5-dioxo-octahydro-1H-inden-4-yl]propanoate + (2Z,4Z)-2-hydroxyhexa-2,4-dienoate + H(+) — reaction