Sites of Photodamage by the Iminium Salt of a Copper Octaethylbenzochlorin

Because the benzochlorin derivative copper (II) alpha-meso-N,N'-dimethyloctaethylbenzochlorin iminium chloride (CDS1) is not fluorescent, sites of drug localization in L1210 cells were detected by indirect methods involving using a series of fluorescent probes. The CDS1-mediated cytotoxicity was associated with mitochondrial damage, a decreased membrane potential and an increase in the heterogeneity of membrane sites of binding of a polar analog of diphenylhexatriene. Although CDS1 is a cationic compound, its accumulation was not impaired in a cell line exhibiting the multidrug resistance phenotype.