1	AZ9	6-methylpyrimido[5,4-E][1,2,4]triazine-5,7(6h,8h)-dione	1.000
2	TOF	1,6-dimethylpyrimido[5,4-E][1,2,4]triazine-5,7(1h,6h)-dione	0.929
3	AZ8	Pyrimido[5,4-E][1,2,4]triazine-5,7(6h,8h)-dione	0.923
4	LUZ	Pteridine-2,4(1h,3h)-dione	0.786
5	TEP	Theophylline	0.733
6	141	Oxypurinol	0.714
7	AZA	8-azaxanthine	0.714
8	XAN	Xanthine	0.714