* To whom correspondence should be addressed.
Received November 22, 2011; Revision received December 22, 2011
Tetraphenylphosphonium (TPP+) and tetramethylrhodamine ethyl ester (TMRE+) cations used as transmembrane carriers of ubiquinone (MitoQ) and plastoquinone (SkQ, SkQR) in mitochondria prevented at nanomolar concentrations the chitosan- or H2O2-induced destruction of the nucleus in epidermal cells of epidermis isolated from pea leaves. The protective effect of the cations was potentiated by palmitate. Penetrating anions of tetraphenylboron (TB–) and phenyl dicarbaundecaborane also displayed protective effects at micromolar concentrations; the effect of TB– was potentiated by NH4Cl. It is proposed that the protective effect of the penetrating cations and anions against chitosan is due to suppression of the generation of reactive oxygen species in mitochondria as a result of the protonophoric effect of the cations plus fatty acids and the anions plus NH4+. Phenol was suitable as the electron donor for H2O2 reduction catalyzed by horseradish peroxidase, preventing the destruction of cell nuclei. The penetrating cations and anions, SkQ1, and SkQR1 did not maintain the peroxidase or peroxidase/oxidase reactions measured by their suitability as electron donors for H2O2 reduction or by the oxidation of exogenous NADH.
KEY WORDS: penetrating ions, tetraphenylphosphonium, tetramethylrhodamine ethyl ester, tetraphenylboron anion, phenyl dicarbaundecaborane anion, cell nucleus destruction, protective effect, plant epidermal cells, chitosan, CN–