Cellular antioxidant activity of phenylaminoethyl selenides as monitored by chemiluminescence of peroxalate nanoparticles and by reduction of lipopolysaccharide-induced oxidative stress

•H2O2 plays an essential role in cellular processes but nevertheless can cause damage to cellular components.•We report chemiluminescent imaging of H2O2 consumption by phenylaminoethyl selenides, using peroxalate nanoparticles.•We show that phenylaminoethyl selenides decrease lipopolysaccharide-induced oxidative stress in human embryonic kidney cells.•Phenylaminoethyl selenide-loaded poly(lactide-co-glycolide) nanoparticles exhibit antioxidant activity in living cells.•Phenylaminoethyl selenides are thus attractive agents for supplementing cellular defenses against reactive oxygen species. Hydrogen peroxide (H2O2), produced in living cells by oxidases and by other biochemical reactions, plays an important role in cellular processes such as signaling and cell cycle progression. Nevertheless, H2O2 and other reactive oxygen species are capable of inducing damage to DNA and other cellular components, and oxidative stress caused by overproduction of cellular oxidants has been linked to pathologies such as inflammatory diseases and cancer. Therefore, new approaches for reducing the accumulation of cellular oxidants are of considerable interest from both a biotechnological and a therapeutic perspective. Recognizing that selenium is an essential component of the active sites of several antioxidant enzymes, we have developed a family of novel phenylaminoethyl selenide compounds that are readily taken up into cells and have low toxicity in vivo. We now report chemiluminescent imaging of hydrogen peroxide consumption by phenylaminoethyl selenides, via the use of peroxalate nanoparticle methodology. Further, we demonstrate the ability of phenylaminoethyl selenides to decrease lipopolysaccharide-induced oxidative stress in human embryonic kidney cells. We also report the successful encapsulation of a phenylaminoethyl selenide within poly(lactide-co-glycolide) nanoparticles, and we show that these selenide-loaded nanoparticles exhibit antioxidant activity in cells. Taken together, these results significantly enhance the attractiveness of phenylaminoethyl selenides as potential agents for supplementing cellular defenses against reactive oxygen species.