1 8TX 8-thioxo-3,7,8,9-tetrahydro-1h-purine-2,6-dione 1.000 2 XAN Xanthine 0.917 3 5JL 2,8-dithioxo-1,2,3,7,8,9-hexahydro-6h-purin-6-one 0.846 4 8HX 8-hydroxy-3,9-dihydro-1h-purine-2,6-dione 0.846 5 B55 2-amino-8-sulfanyl-1,9-dihydro-6h-purin-6-one 0.846 6 URC Uric acid 0.846 7 HPA Hypoxanthine 0.833 8 37T Theobromine 0.786 9 MUA 9-methyl uric acid 0.786 10 TEP Theophylline 0.786 11 290 6-methyl-3,9-dihydro-2h-purin-2-one 0.769 12 2ON 2-sulfanyl-1,9-dihydro-6h-purin-6-one 0.769 13 AZA 8-azaxanthine 0.769 14 BOA 2-bromo-6-hydroxy-purine 0.769 15 GUN Guanine 0.769 16 IGA 6-amino-3,7-dihydro-2h-purin-2-one 0.769 17 KB5 6-azanyl-9~{H}-purine-8-thiol 0.769 18 209 8-amino-1,3-dimethyl-3,7-dihydropurine-2,6-dione 0.733 19 8NX 8-nitro-3,7-dihydro-1h-purine-2,6-dione 0.733 20 CFF Caffeine 0.733 21 H33 8-chloro-1,3-dimethyl-3,7-dihydro-1h-purine-2,6-dione 0.733 22 IUP 5-(hydro)peroxoisourate 0.733 23 5JQ 2-thioxo-2,3,7,9-tetrahydro-1h-purine-6,8-dione 0.714 24 8IG 8-iodo-guanine 0.714 25 8WT 8-methylsulfanyl-7~{H}-purin-6-amine 0.714 26 9MG 9-methylguanine 0.714 27 ANG 8-aminoguanine 0.714 28 AZ8 Pyrimido[5,4-E][1,2,4]triazine-5,7(6h,8h)-dione 0.714 29 BRG 8-bromoguanine 0.714 30 LUZ Pteridine-2,4(1h,3h)-dione 0.714 31 MY6 2-amino-7-methyl-1,7-dihydro-6h-purin-6-one 0.714 32 OXG 8-oxoguanine 0.714