Interaction of [ReO(SNS)(S)] and [99mTcO(SNS)(S)] mixed ligand complexes with glutathione:: isolation and characterization of the product

Interaction of the complex [ReO((C2H5)(2)NCH2CH2N(CH2CH2S)(2)) (4-CH3O-C6H4S)] (1) with glutathione (GSH) in DMSO-d(6) led to isolation of the complex [ReO((C2H5)(2)NCH2CH2N(CH2CH2S)(2))(GS)] (2) in which glutathione has replaced the coligand 4-methoxythiophenol. Identification of 2 was achieved by MS, NMR, UV-Vis, and IR spectroscopies. The interaction of glutathione with the complex [(TcO)-Tc-99m((C2H5)(2)NCH2CH2N(CH2CH2S)(2))(4-CH3O-C6N4S)] (3), which is analogous to 1, was also studied at tracer level by HPLC and it was demonstrated that the complex [(TcO)-Tc-99m((C2N5)(2)NCH2CH2N(CH2CH2S)(2))(GS)] is also formed. Complex 3 is a representive of the [(TcO)-Tc-99m(SNS)(S)] class of potential brain imaging agents that show high brain uptake and retention in animals tested. The replacement of the coligand 4-methoxythiophenol by glutathione transforms the originally Lipophilic complex to hydrophilic; this is being investigated further as one of the possible pathways in the retention mechanism of this type of complex. (C) 1998 Elsevier Science S.A. All rights reserved.