Psi-Screen, an In Vitro Toxicity Test System: Applications in the Bioassay of Perfumes and Fragrance Chemicals

David E. Griffiths

The effects of 65 perfume formulations (perfume oils, perfumes, eau de parfum, eau de toilette) on mitochondrial membrane potential (ΔΨm) and mitochondrial respiration have been investigated using a mitochondria-based assay for ΔΨm, termed Psi-Screen. All the perfume formulations tested are highly active in the Psi-Screen assay, and the major site of inhibition in all cases is NADH-ubiquinone reductase (Complex I). This is confirmed in studies on the inhibition of NADH oxidase and NADH-ubiquinone reductase. Some formulations also inhibit succinate oxidation at either Complex II or Complex III. Evidence for the inhibition of mitochondrial ATPase is presented, as well as for the induction of reactive oxygen species production by perfume inhibition of Complex I. Thus, perfume formulations are multiple inhibitor mixtures which inhibit multiple bioenergetic functions at high dilutions (103 to 7 × 104). The implications of these findings are discussed with respect to cell toxicity via necrosis and/or apoptosis. Twenty candidate fragrance chemicals were investigated and all inhibited Complex I (5 at < 35μM). Mass screening strategies and high-throughput screening assays are discussed.