Photosensitized generation of singlet molecular oxygen by endogenous substances of the eye lens

It is shown that kinurenine derivatives, harmane (beta-carboline) and tetracycline hydrochloride known as photosensitizers of cataractogenesis in lens produce luminescence of singlet molecular oxygen (1O2) under photoexcitation in air saturated aqueous (D2O) solution. The quantum yields of the 1O2 generation by these substances are determined. The data obtained by this direct 1O2 determination technique suggest that 1O2 might take part in cataractogenesis.