Abstract
Purpose: :
Information on the significance of Tea/Coffee alkaloids on the physio-pathology of lens and cataract formation is presently unknown. Based on our present findings, we hypothesize that they exert an anti-cataractogenic effect. The purpose of these experiments was hence to verify this hypothesis using caffeine, the most prevalent ingredient of common beverages and energy drinks.
Methods: :
The above hypothesis has been evaluated by lens culture experiments where cataract development was induced by irradiation with UV-B (302nm). Freshly isolated mice (CD-1) lenses were incubated in Tyrode, either in dark or exposed to UV-B, in the absence or presence of caffeine (5mM) . The period of incubation was 5 hrs. The physiological status of the lenses was assessed by measuring active transport of rubidium ions (86Rb+), in terms of its distribution ratio attained between the medium of incubation and the lens water. This was additionally assessed in terms of the levels of ATP and GSH in the lenses.
Results: :
The exposure level of UV was adjusted (0.6mW/cm2) so as to decrease the rubidium transport activity to about 60% of the basal controls run in dark. This was accompanied with simultaneous decreases in the levels of GSH and ATP to 50% and 40% of the dark controls. These deteriorations were significantly preventable in the presence of caffeine. The loss of rubidium transport was nearly completely thwarted. Similar protective effects were shown in terms of the maintenance of GSH and ATP levels. Spectroscopic studies showed that caffeine has an absorption maxima at 270nm with shoulder up to 302nm, coincident with the emission maxima of the lamp used in these experiments.
Conclusions: :
While several compounds such as pyruvate and ascorbate have been previously shown to protect lens against damage caused by reactive oxygen species and UV-A irradiation , information on agents that might be effective against UV-B induced possible lens damage in vivo are highly limited, if any. The present results demonstrate that caffeine could be effective in this regard. The observed effects are attributable in part to caffeine's UV screening effect, acting in combination with its other properties such as via scavenging oxyradicals and maintaining cyclic AMP, the latter by inhibiting phosphodiesterase. Further mechanistic studies are hence in progress.
Keywords: oxidation/oxidative or free radical damage • cataract • radiation damage: light/UV