Wm. Kazmierski et al., IRON CHELATES BIND NITRIC-OXIDE AND DECREASE MORTALITY IN AN EXPERIMENTAL-MODEL OF SEPTIC SHOCK, Proceedings of the National Academy of Sciences of the United Statesof America, 93(17), 1996, pp. 9138-9141
The hydroxamic acid siderophore ferrioxamine B [Fe-III(HDFB)(+)] and t
he iron complex of diethylenetriaminepentaacetic acid [Fe-III(DTPA)(2-
)] protected mice against death by septic shock induced by Corynebacte
rium parvum + lipopolysaccharide. Although Fe-III(DTPA)(2-) aas somewh
at more effective than Fe-III(HDFB)(+), the iron-free ligand H4DFB+ wa
s significantly more effective than DTPA. The hydroxamic acid chelator
has a much higher iron affinity than the amine carboxylate, allowing
for more efficient formation of the Fe-III(HDFB)(+) complex upon admin
istration of the iron-free ligand. Electrochemical studies show that F
e-III-(DTPA)(2-) binds NO stoichiometrically upon reduction to iron(II
) at biologically relevant potentials to form a stable NO adduct, In c
ontrast, Fe-III(HDFB)(+) is a stable and efficient electrocatalyst for
the reduction of NO to N2O at biologically relevant potentials, These
results suggest that the mechanism of protection against death by sep
tic shock involves NO scavenging and that particularly effective drugs
that operate a low dosages may be designed based on the principle of
redox: catalysis. These complexes constitute a new family of drugs tha
t rely on the special ability of transition metals to activate small m
olecules, In addition, the wealth of information available on sideroph
ore chemistry and biology pro,ides an intellectual platform for furthe
r development.