Biomedical Engineering Reference
In-Depth Information
(A)
(B)
(C)
FIGURE 10.4
Selected ligands from Table 10.4. Structures of BAL (A); d-PEN (B); DFO (C); carbon atoms
are black, oxygen red, nitrogen blue, and sulfur green. Hydrogen atoms (light gray) are only shown in the two
former structures.
concentration of calcium ions will be lowered, often with severe muscle spasms as a result.
Instead, the CaH
2
EDTA salt is recommended, and in general the diet should be supplemented
with essential metal ions during EDTA treatment.
10.5.1.4 Desferrioxamine
The siderophores are naturally occurring small molecule chelates secreted by many microorganisms.
One important example of a siderophore is desferrioxamine (DFO, desferral) (Figure 10.4C).
A large amount of (hard) oxygen donor atoms in an octahedral geometry render it highly specii c
toward iron(III), with a stability constant of not less than 10
31
M
−1
. The chelate is used in the treatment
of acute iron poisoning and in certain cases of anemia where iron is accumulated in liver and heart.
Binding constants for the corresponding Fe(II) complexes are much smaller due to larger ionic
radius and smaller charge, and release of iron can be induced simply by reduction of Fe(III). Since
the coordination chemistry of Al
3+
is similar to that of Fe
3+
, DFO can also be used in cases of aluminum
poisoning. Incidentally, chelate formation also lies behind the body's strategy of producing fever in
cases of infections. The higher temperature reduces the bacteria's ability to synthesize particular
iron-chelating ligands.
10.6 INORGANIC CHEMISTRY AND PHARMACEUTICALS
So far, the pharmaceutical industry has mainly developed drugs based upon organic chemistry and
on natural products. However, the remaining part of the periodic table offers an ever-increasing
number of diagnostics and genuine pharmaceuticals. In the following text we shall give a brief
review of some pertinent examples that illustrate the aforementioned principles.
