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

Abstract

Interaction of the complex [ReO((C 2H 5) 2NCH 2CH 2N(CH 2CH 2S) 2)(4-CH 3OC 6H 4S)] ( 1) with glutathione (GSH) in DMSO- d 6 led to isolation of the complex [ReO((C 2H 5) 2NCH 2CH 2N(CH 2CH 2S) 2)(GS)] ( 2) in which glutathione has replaced the coligand 4-methoxy-thiophenol. Identification of 2 was achieved by MS, NMR, UV-Vis, and IR spectroscopies. The interaction of glutathione with the complex [ 99mTcO((C 2H 5) 2NCH 2CH 2N(CH 2CH 2S) 2)(4-CH 2OC 6H 4S)] ( 3), which is analogous to 1, was also studied at tracer level by HPLC and it was demonstrated that the complex [ 99mTcO((C 2H 5) 2NCH 2CH 2N(CH 2CH 2S) 2)(GS)] is also formed. Complex 3 is a representative of the [ 99mTcO(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.