Differential cytoprotective effect of copper- and iron-containing chlorophyllins against oxidative stress-mediated cell death

Chlorophyllin (CHL), a copper-containing chlorophyll derivative, was previously reported to possess reactive oxygen species (ROS) scavenging activity. However, the antioxidant property of iron-containing chlorophyllin, iron chlorin e6 (FeCe6), has not been explored in detail. This study systematically investigated the antioxidant capacity of two chlorophyllins, CHL and FeCe6, and their cytoprotective effects against ROS toxicity in human Jurkat T-cells. Both CHL and FeCe6 exhibited a wide range of antioxidant activities to ABTS radical, singlet oxygen, peroxynitrite, and peroxyl radical. Notably, FeCe6 exerted a significant suppressive effect on hydrogen peroxide-dependent cytotoxicity and apoptosis in Jurkat T-cells, while negligible or much weaker inhibition was observed by CHL. This differential cytoprotective effect is likely due to the different hydrogen peroxide scavenging capacity of two chlorophyllins. Moreover, FeCe6 attenuated menadione-induced cell death and tumour necrosis factor (TNF)-alpha-induced I kappa B phosphorylation via scavenging of intracellular ROS. Taken together, the results suggest that FeCe6 is a promising cytoprotective antioxidant against oxidative stress-mediated cellular toxicity.