Catalysis of the reaction: 3,4-dihydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione + O2 = 3-hydroxy-5,9,17-trioxo-4,5:9,10-disecoandrosta-1(10),2-dien-4-oate + H+.
3,4-dihydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione:oxygen 4,5-oxidoreductase (decyclizing)