Inhibitory Effects Of Caffeic Acid Phenethyl Ester On Oxidative Damage To Lipid And Human Red Blood Cells

Oxidative stress refers to excess production of ROS due to the imbalance between cellular production of ROS and the ability of cells to defend themselves against them. Oxidative stress has been considered to be a major cause of cellular injuries in a variety of chronic health problems, such as carcinogenesis and neurodegenerative disorders. Caffeic acid phenethyl ester (CAPE), caffeic acid, ferulic acid, and ethyl ferulate are constituents of propolis and structurally related, which allowed us to gather important information regarding the structure-activity relationships underlying the biological activity of such compounds. In this work, we have investigated the direct scavenging effects of the antioxidants on 1,1-diphenyl-2picrylhydrazyl (DPPH) radicals, galvinoxyl radicals , as well as the anti-lipoperoxidative capacity on human erythrocytes hemolysis and rat liver microsomal membranes peroxidation induced in vitro by two different sources of free radicals: 2,2'-azobis (2-amidinopropane) (AAPH) and Fe2+/ascorbate (OH·).And the LDL peroxidation was initiated either by copper ions or by AAPH. The results established that the radical scavenging activity of the compounds increased with increasing numbers of hydroxyl groups or catechol moieties in the molecule, while in the biomembrane systems, the antioxidative activity of the test compounds depends not only on the hydroxyl groups or catechol rings but also on the polarity and hydrophobicity of the antioxidants. In addition, CAPE is the most effective antioxidant of the compounds we tested in our in vitro systems.The compounds,such as CAPE,caffeic acid, ferulic acid and ethyl ferulate, have different scavenging effects on DPPH and galvinoxyl radicals.Their scavenging activity of both radicals decreased in the following order: CAPE > caffeic acid > ferulic acid > ethyl ferulate . All the compounds show protecting effects on AAPH-induced hemolysis of human RBC.On basis of the inhibition period, the inhibitory activity against AAPH-induced erythrocyte hemolysis follows the sequence of CAPE > ethyl ferulate > caffeic acid > ferulic acid. The inhibition of hydroxyl radical induced peroxidation of rat liver microsomes by the antioxidants follows the sequence of CAPE > ethyl ferulate > caffeic acid > ferulic acid. Human LDL peroxidation, induced by AAPH or Cu2+, can be inhibited by CAPE,and two important compounds of the flavones contents in propolis, quercetin and rutin .