Prooxidant toxicity of polyphenolic antioxidants to HL‐60 cells: description of quantitative structure‐activity relationships

Polyphenolic antioxidants exhibited a dose‐dependent toxicity against human promyelocytic leukemia cells (HL‐60). Their action was accompanied by malondialdehyde formation, and was partly prevented by desferrioxamine and the antioxidant N,N′‐diphenyl‐p‐phenylene diamine. This points to a prooxidant character of their cytotoxicity. A quantitative structure‐activity relationship (QSAR) has been obtained to describe the cytotoxicity of 13 polyphenolic antioxidants belonging to three different groups (flavonoids, derivatives of gallic and caffeic acid): log cL₅₀ (μM)=(2.7829±0.2339)+(1.2734±0.4715) E _p/2 (V)−(0.3438±0.0582) log P (r ²=0.8129), where cL₅₀ represents the concentration for 50% cell survival, E _p/2 represents the voltammetric midpoint potential, and P represents the octanol/water partition coefficient. Analogous QSARs were obtained using enthalpies of single‐electron oxidation of these compounds, obtained by quantum‐mechanical calculations. These findings clearly point to two important characteristics determining polyphenol cytotoxicity, namely their ease of oxidation and their lipophilicity.