PHOTOREACTIVITY OF BIOLOGICALLY-ACTIVE COMPOUNDS .8. PHOTOSENSITIZED POLYMERIZATION OF LENS PROTEINS BY ANTIMALARIAL-DRUGS IN-VITRO

The drugs commonly used in the treatment of malaria are photochemicall y unstable. Several of these compounds cause dermal and ocular toxic r eactions that may be light induced. The in vitro photopolymerization o f calf lens proteins in the presence of antimalarial drugs was studied as part of a screening of the photochemical properties and phototoxic capabilities of these compounds. The pseudo-first-order rate constant for the reaction was calculated, and related to the amount of light a bsorbed by the compounds in order to determine the relative photosensi tizing effect of each drug. The reaction mechanisms were evaluated by adding a variety of quenchers to the reaction medium during irradiatio n. Based on the results obtained in this study and previous knowledge about the pharmacokinetic behavior of these compounds, several of the drugs investigated have to be considered as potential photosensitizers in the human lens, the retina and the skin.