Synthesis of derivatives of phosphonic glutathione analogs

Design and synthesis of glutathione analogues

This review reports recent structural modifications (since 1989) performed on the glutathione molecular both in the oxidized and reduced form. Relevant chemical aspects, biochemical consequences and therapeutical implications are illustrated. Natural thiols related to glutathione are also considered.

Synthesis and activity of the glutathione analogue gamma-(L-gamma-oxaglutamyl)-L-cysteinyl-glycine

An efficient synthesis of the backbone modified glutathione analogue gamma-(L-gamma-oxaglutamyl)-L-cysteinyl-glycine (7), characterized by the presence of an urethane O-CO-NH linkage replacing the gamma-glutamylic CH2CO-NH fragment is described. The new analogue has been fully characterized by 1H- and 13C-NMR, and FAB-MS. Compound 7 was tested for inhibition of gamma-glutamyl-transferase activity and was found to be a non-competitive inhibitor of hog kidney gamma-glutamyltransferase (EC 2.3.2.2).

Synthesis and activity of the glutathione analogue gamma-(L-gamma-azaglutamyl)-L-cysteinyl-glycine

The backbone-modified glutathione analogue gamma-(L-gamma-azaglutamyl)-L-cysteinyl-glycine 7, characterized by the presence of a NHCONH urea linkage deriving from the replacement of the native Glu gamma-CH2 with the aza (NH) group, was synthesized and fully characterized by FAB-MS, 1H- and 13C-NMR. Potential of 7 and its oxidized form 6 as gamma-glutamyltransferase inhibitors was investigated. Both compounds 7 and 6 were found to be competitive inhibitors of hog kidney gamma-glutamyltransferase (EC 2.3.2.2.) by binding at the donor site: the reduced analogue is a more efficient inhibitor than glutathione of the gamma-glutamyl transfer reaction. Inhibition at the acceptor site, which is also present, appears to be more complex. In particular, un-competitive inhibition is observed for compound 7. The results indicate that gamma-azapeptides of type 7 may represent interesting targets in the search for stable inhibitors of gamma-glutamyltransferases.