1H-purine-2,6,8(3H)-trione, 7,9-dihydro- 7,9-dihydro-1H-purine-2,6,8(3H)-trione InChI=1/C5H4N4O3/c10-3-1-2(7-4(11)6-1)8-5(12)9-3/h(H4,6,7,8,9,10,11,12