PHOTOREACTIVITY OF BIOLOGICALLY-ACTIVE COMPOUNDS .11. PRIMAQUINE AND METABOLITES AS RADICAL INDUCERS

Reduction of ferricytochrome C and oxidation of haemoglobin was used t o examine Iedox properties of primaquine, metabolites and photodegrada tion products of the drug. The influence of oxygen radicals (O-2 radic al anion and OH .) were studied by the addition of oxygen radical scav engers. Photodecomposition of primaquine (80 mW/cm(2), xenon lamp, 290 -800 nm) prior to dark-incubation resulted in a substantial accelerate d drug-induced O-2 radical anion formation and haemoglobin oxidation. Formation of OH . (dark reaction) could be detected after photochemica l degradation of primaquine. In the presence of erythrocytes the forma tion of oxygen radicals induced by the photodecomposition products was even more pronounced. A high oxygen content in the medium during irra diation accelerated the photodecomposition-rate of primaquine. The met abolite 6-desmethyl primaquine was a more potent O-2 radical anion pro ducer and haemoglobin oxidizer than primaquine (dark reactions). Durin g irradiation (80 mW/cm(2): 290-800 nm) primaquine formed more O-2 rad ical anion and produced a detectable level of OH . compared to the dar k reactions.