P15 Organic and inorganic hydrogen sulfide donors: Releasing properties and biological activities

The crucial role played by hydrogen sulfide in biology [1] has called for the development of new molecular tools to assist the biologists in their studies, like the numerous probes to detect hydrogen sulfide in cells synthesized in the last two years [2] During this time, hydrogen sulfide donors have emerged to replace the widely used salts NaHS or Na2S, which are instantaneous H2S donors, that consequently do not reproduce the steady biosynthesis [3] . Here, we will present our “chemist’s” approach towards such donors, with two strategies based either on inorganic or on organic molecules. The iron complex 2 from scheme A [4] , the first Fe (II)-SH complex in which the hydrogen (sulfido) ligand is stabilized by H-bond, slowly liberates H2S in organic solutions through an original equilibrium involving a protonation/deprotonation process on the ligand. On another hand, the organic donors from Scheme B [5] are activated by thiols and able to release H2S in simple buffer as well as in more complex systems like cells or tissues. In particular, the stability of the donor MeCOSSCOMe towards oxidation makes it a useful alternative to the use of sulfide salts in ex-vivo assays of the vascular function, with the lowest EC50 reported to date for the relaxation of pre-contracted rat aorta rings under the standard 95% O2/5% CO2 conditions.