Biomedical Engineering Reference
In-Depth Information
To scavenge reactive oxygen
species, a well-known endogenous
antioxidant, glutathione (GSH), was examined.
The results of investigating GSH (dissolved in saline) as a potential
antioxidant against HA degradation are reported in
Figure 5.4
. It
can be seen that within the 5-h measurement, the application of
the GSH concentrations (50 and 100 mM) resulted in a remarkable
protection of the HA macromolecules against degradation, leading
to the complete inhibition of the solution viscosity decrease. The
higher the GSH concentration used, the longer the observed stationary
interval in the sample h values. However, at a concentration of 10
mM GSH did not completely inhibit HA degradation. At the lowest
concentration, i.e., 1 mM GSH, a pro-oxidative effect can be observed.
That may be ascribed to a formation of an intermediate [GSSG]
·
-
(glutathione disulfide anion radical) by reacting GS
·
(glutathiyl
radical) and GS
-
, which under aerobic conditions converts molecular
oxygen to hydrogen peroxide [29], as follows in
Equations 5.2
-
5.6
:
GSH + HO
·
→ GS
·
+ H
2
O
(5.2)
GSH → GS
-
+ H
+
(5.3)
GS
·
+ GS
-
→ [GSSG]
·
-
(5.4)
[GSSG]
·
-
+ O
2
→ GSSG + O
2
·
-
(5.5)
O
2
·
-
+ O
2
·
-
+ 2H
+
→ H
2
O
2
+ O
2
(5.6)
GSH added to the reaction mixture 1 h later, i.e. during the
degradation process, demonstrated similar efficacy as is illustrated
in
Figure 5.4
, panel B. At higher concentrations of GSH (50, 100
and 200 mM) a decrease of h was only slight, around 1 mPa.s.
GSH at a concentration of 10 mM showed a mild protection of HA
against degradation. However, GSH at a concentration of 1 mM was
ineffective and its corresponding curve 1 was identical to the reference
one (0) up to 240 min.
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