Antioxidants are considered to have important roles in protecting the
eye against radiation, oxygen toxicity and other threats. Several wate
r-soluble electrochemically-active compounds that might function as an
tioxidants in vitreous humor of rabbit, rat and bovine eyes were ident
ified and quantitated. In that the rat is a nocturnal animal species a
nd the other two are diurnal, the results allow a tentative evaluation
on the comparative physiology of light-dark behavior patterns that in
fluence this ocular fluid. All analyses were performed by HPLC with el
ectrochemical detection. The utility of this approach is that componen
ts of vitreous humor can be identified by their retention time and by
their characteristic response when the voltages of the two sensing ele
ctrodes are progressively brought together. Four compounds regarded as
functional antioxidants in the animal kingdom were identified and qua
ntitated. Other antioxidants known to be present in several biological
fluids are not present at detectable or significant levels in vitreou
s humor; metabolites or precursors of these might be present in trace
quantities. (C) 1997 Academic Press Limited.