Non-enzymatic antioxidant defense system in plants

Abstract

The defense system in plants have efficient complex enzymatic and non-enzymatic antioxidant defense systems to avoid the toxic effects of free radicals. Chloroplasts and mitochondria are the two main powerhouses and sites of reactive oxygen species (ROS) generation within plant cells AA is the most abundant and the most extensively studied antioxidant compound. It is can donate electrons to a wide range of enzymatic and non-enzymatic reactions. Majority of AA in plant cells is the result of Smirnoff-Wheeler pathway, catalyzed by L-galactano-γ-lactone dehydrogenase in the plant mitochondria, with the remaining being generated from D-galacturonic acid. Vitamin E (α-tocopherol), is an efficient lipid soluble antioxidant that functions as a ‘chain breaker’ during lipid peroxidation in cell membranes and various lipid particles including low-density lipoprotein (LDL). It functions to intercept lipid peroxyl radicals (LOO) and to terminate the lipid peroxidation chain.