A concise appraisal of lipid oxidation and lipoxidation in higher plants

Abstract

Polyunsaturated fatty acids present in plant membranes react with reactive oxygen species through so-called lipid oxidation events. They generate great diversity of highly-reactive lipid-derived chemical species, which may be further degraded enzymatically or non-enzymatically originating new components like Reactive Carbonyl Species (RCS). Such RCS are able to selectively react with proteins frequently producing loss of function through lipoxidation reactions. Although a basal concentration of lipoxidation products exists in plants (likely involved in signaling), their concentration and variability growth exponentially when plants are subjected to biotic/abiotic stresses. Such conditions typically increase the presence of ROS and the expression of antioxidant enzymes, together with RCS and also metabolites resulting from their reaction with proteins (advanced lipoxidation endproducts, ALE), in those plants susceptible to stress. On the contrary, plants designed as resistant may or may not display enhanced levels of ROS and antioxidant enzymes, whereas levels of lipid oxidation markers as malondialdehyde (MDA) are typically reduced. Great efforts have been made in order to develop methods to identify and quantify RCS, ALE, and other adducts with high sensitivity. Many of these methods are applied to the analysis of plant physiology and stress resistance, although their use has been extended to the control of the processing and conservation parameters of foodstuffs derived from plants. These foods may accumulate either lipid oxidation/lipoxidation products, or antioxidants like polyphenols, which are sometimes critical for their organoleptic properties, nutritional value, and health-promoting or detrimental characteristics. Future directions of research on different topics involving these chemical changes are also discussed.

Keywords: Advanced lipoxidation endproducts; Food; Lipid peroxides; Reactive carbonyl species; Reactive oxygen species; Stress.

Graphical abstract

Fig. 1

An overview of RCS generation, lipid oxidation and lipoxidation in Higher Plants and foodstuffs. Oxidative processes occur in plants and are enhanced by stress situations. Oxidation in plant lipid molecules (lipid oxidation) by ROS is frequently followed by modifications in proteins (protein lipoxidation), caused by the highly-reactive derived carbonyl-containing fragments of fatty acids and other lipid components. RCS may also play important roles in signaling, gene regulation, generation of stress resistance, etc. Lipid oxidation and protein lipoxidation are enhanced with biotic and abiotic stresses. Plants are primarily used as raw material by food industry, and foodstuffs may contain RCS and ROS, with levels sometimes enhanced by food processing procedures, greatly affecting food quality. Health benefits and drawbacks can be attributed to these components.