Patent ID: 8778309

Claim:
A method of assessing renal function, the method comprising: administering into a body of a patient an effective amount of a pyrazine derivative that is capable of being renally cleared from the body, wherein the pyrazine derivative is hydrophilic and capable of at least one absorbing and emanating spectral energy of at least about 400 nm; exposing the pyrazine derivative that is in the body to spectral energy of at least about 400 nm, wherein the exposing causes spectral energy to emanate from the pyrazine derivative; detecting the spectral energy emanated from the pyrazine derivative in the body; and assessing renal function of the patient based on the detected spectral energy; wherein the pyrazine derivative is represented by Formula I, wherein: X 1 and X 2 are electron withdrawing substituents, each of which is independently selected from the group consisting of —CN, —CO 2 R 1 , —CONR 2 R 3 , —COR 4 , —NO 2 , —SOR 5 , —SO 2 R 6 , —SO 2 OR 7 and —PO 3 R 8 R 9 ; Y 1 and Y 2 are electron donating substituents, each of which is independently selected from the group consisting of —OR 10 , —SR 11 , —NR 12 R 13 , —N(R 14 )COR 15 and Z 1 is selected from the group consisting of a direct bond, —CR 16 R 17 —, —O—, —NR 18 —, —NCOR 19 —, —S—, —SO— and —SO 2 —; each of R 1 to R 19 is independently selected from the group consisting of hydrogen, C3-C6 polyhydroxylated alkyl, ((CH 2 ) 2 —O—(CH 2 ) 2 —O) a —R 40 , C1-C10 alkyl, C5-C10 aryl, C5-C10 heteroaryl, (CH 2 ) a OH, (CH 2 ) a CO 2 H, (CH 2 ) a SO 3 H, (CH 2 ) a SO 3 − —, (CH 2 ) a OSO 3 H, (CH 2 ) a OSO 3 − —, (CH 2 ) a NHSO 3 H, (CH 2 ) a NHSO 3 − , (CH 2 ) a PO 3 H 2 , (CH 2 ) a PO 3 H, (CH 2 ) a PO 3 = —, (CH 2 ) a OPO 3 H 2 , (CH 2 ) a OPO 3 H − and (CH 2 ) a OPO 3 − ; R 40 is selected from the group consisting of hydrogen, C1-C10 alkyl, C5-C10 aryl, C5-C10 heteroaryl, (CH 2 ) a OH, (CH 2 ) a CO 2 H, (CH 2 ) a SO 3 H, (CH 2 ) a SO 3 − —, (CH 2 ) a OSO 3 H, (CH 2 ) a OSO 3 − , (CH 2 ) a NHSO 3 H, (CH 2 ) a NHSO 3 − , (CH 2 ) a PO 3 H 2 , (CH 2 ) a PO 3 H − , (CH 2 ) a PO 3 = —, (CH 2 ) a OPO 3 H 2 , (CH 2 ) a OPO 3 H − and (CH 2 ) a OPO 3 ; and each of a, m and n range from 1 to 6.