Sugars as hydroxyl radical scavengers Proof-of-concept by studying the fate of sucralose in Arabidopsis
Matros, Andrea * Peshev, Darin * Peukert, Manuela Mock, Hans-Peter Van den Ende, Wim # ×
The Plant Journal vol:82 pages:822-839
Substantial reactive oxygen species (ROS) formation is inevitable in aerobic life forms. Due to their extremely high reactivity and short lifetime, hydroxyl radicals form a special case, because cells have not been able to develop enzymes to detoxify these most dangerous ROS. Thus, scavenging of hydroxyl radicals can only occur by an accumulation of higher levels of simple organic compounds. Previous works demonstrated that plant-derived sugars show hydroxyl radical scavenging capabilities during Fenton reactions with Fe2+ and hydrogen peroxide in vitro, leading to the formation of less detrimental sugar radicals that may be subject of regeneration to non-radical carbohydrates in vivo. Here, we provide further evidence for the occurrence of such radical reactions with sugars in planta, by following the fate of sucralose, an artificial analogue of sucrose, in Arabidopsis tissues. The expected sucralose recombination and degradation products were detected both in normal and stressed plant tissues. Oxidation products of endogenous sugars have also been determined in planta for Arabidopsis and barley, and were shown to increase in their abundance relative to the non-oxidized precursor during oxidative stress conditions. We concluded that such non-enzymatic reactions with hydroxyl radicals form an integral part of plant antioxidant mechanisms contributing to cellular ROS homeostasis and may be more important than generally assumed. This is discussed in relation to the recently proposed roles for Fe2+ and hydrogen peroxide in processes leading to the origin of metabolism and the origin of life.