PHOTOREACTIVITY OF BIOLOGICALLY-ACTIVE COMPOUNDS .7. INTERACTION OF ANTIMALARIAL-DRUGS WITH MELANIN IN-VITRO AS PART OF PHOTOTOXICITY SCREENING

The drugs commonly used in the treatment of malaria are photochemicall y unstable. Several of these compounds accumulate in melanin-rich tiss ues and cause toxic reactions which may be light induced. As part of t he screening of the photochemical properties and phototoxic capabiliti es of antimalarials, the in vitro interaction of eight antimalarials w ith melanin was studied. The dissociation constant for the drug-melani n complex and the relative number of binding sites on melanin were est imated for six of the drugs using a curve-fitting program. The reactio n rate for the formation of the melanin-drug complex was determined, a nd the complexes were further characterized by zeta potential measurem ents.