Abstract
Purpose: :
Intraocular generation of reactive oxygen species (ROS) has been shown to induce cataracts in vitro as well as in vivo. The generation of these species is initiated by the reaction of redox active metals with oxygen. Studies are hence in progress to develop novel scavengers of ROS so generated, effective in preventing such damage to the lens and eventually prevent cataract formation. These studies have been done pertaining to the possible effectiveness of caffeine.
Methods: :
The protective effect of caffeine has been studied in mouse lens culture studies wherein the isolated lenses were incubated in medium 199 for 18 hrs at 37°C. The source of metal ion was a soluble form of iron (Fe8Br8) obtained from Dr. Naresh Dalal of Florida State Univ. Incubations were done in the absence and presence of caffeine. Tissue damage was assessed by measuring the active transport of 86Rb+. The contents of ATP and GSH were also determined. Simultaneous studies were done with Tempol.
Results: :
The Fe complex was found to be highly effective in inducing tissue damage. In the presence of 0.1mM complex, the 86Rb+ uptake was significantly reduced, to ~60% of the controls incubated without Fe. In addition, the levels of ATP and GSH were also decreased to 60% and 50% of the controls, respectively. Addition of caffeine to the medium was significantly protective, as reflected by its inhibitory effect on the deactivation of the pump as well as by the maintenance of the levels of ATP and GSH. That the protective effect is due to its oxyradical scavenging properties is evidenced by a similar protective effect of Tempol, a well-known scavenger of ROS. Since no H2O2 was detected in the medium, the damaging process is attributable to a direct OH. generation by the complex.
Keywords: oxidation/oxidative or free radical damage • antioxidants • metabolism